Materials- nanoelectronics and nanophotonics

Resume : Pesticide and herbicide residues in foods and water bodies are a growing concern to human health, and effective detection of such residues plays a significant role in the reduction of such emerging threats. In recent years advanced carbon-based materials such as graphene and functionalized diamond have been used for the quantification of these pesticides in different media including water and plants. In this work, flexible laser-induced graphene (LIG) and highly electrically conductive boron-doped hybrid carbon nanowalls (HCNWs) were produced for effective detection of Paraquat (PQ) in real water. PQ was detected with dilution in phosphate buffer solution (PBS) with optimized pH along with optimized parameters of the square wave voltammetry (SWV) method. LIG is a 3D porous material fabricated by patterning with the help of CO2 laser irradiation on polyimide (PI) films and has unique properties such as high conductivity, biocompatibility, and high porosity. On the other hand, in HCNWs sp2-bonded graphene has been integrated over a three-dimensional curved wall-like network of sp3-bonded diamond. We discuss various techniques, such as SEM, TEM, Raman spectroscopy, XPS and XRD to characterize the microstructures of these two materials. Both samples show a higher liner range, excellent current response, and lower limit of detection (LoD) and a very good average recovery rate of paraquat when spiked in real water samples. Finally, we highlight some fundamental issues pertaining to the above application.

Resume : Atomically regulated (1D) nanowires can be as small as a single atom in width and are the smallest ordered periodic materials. We can template such structures within in the narrowest of single walled carbon nanotubes (SWCNTs), allowing the study of the fundamental properties of matter, such as nanoscale phase transformations, the energetics of confined crystal structure formation and the spectroscopic evolution of both the included crystals and the host nanotubes. These materials test the state of the art in electron microscopy and associated spectroscopies but their extremely small size also lends them to ab initio theoretical investigations whereby their stability, electronic properties can be studied. Our latest work shows how incorporation of cesium iodide in SWCNTs 0.8-1.1 nm in diameter causes the formation of linear -I-Cs-I-Cs-I- chains in the narrowest tubules and helical 2×1 CsI crystals in slightly wider tubules. In the former, this causes redshifts in the measured photoluminescence (PL) of the encapsulating nanotubes whereas the 2×1 CsI crystals cause an oval distortion in the tubules resulting this time in a blue shift. We have also just reported the application of even more sensitive transient absorption spectroscopy (TAS) to resolve how incorporation of ‘zig-zag’ chains of HgTe modify the electron-phonon interaction in this ultranarrow SWCNTs. Somewhat wider diameter (1.2-1.6 nm) SWCNTs are equally interesting. We can now report reversible phase change behaviour in nanotubes formed on this scale when filled with Sb2Te3. Additionally, we are also able to create the smallest scale perovskite-like phases ever observed when templated in this diameter range.

Resume : The aerosol (floating catalyst) chemical vapor deposition is one of the most promising approaches for the production of single-walled carbon nanotubes (SWCNTs) because of its excellent scalability, superior material quality, and robust nanotube collection technique (1). In particular, it enables direct fabrication of highly conductive SWCNT films showing a comparable performance with indium-tin-oxide – commonly-used transparent electrode material (2). Previously, numerous works in the field were focused on the boosting of SWCNT film transparent conductive performance. The improvement in film conductivity is usually associated with a dramatic decline in the synthesis yield since an extremely diluted catalyst is used to prevent aerosol bundling (3). The trade-off between material performance and productivity of the synthesis process challenges cost-effective production of SWCNT films and as follows, hampers ITO replacement. For this reason, simultaneous enhancement of material performance and synthesis productivity is one of the main steps toward widespread SWCNT implementation in transparent electronics. We believe the advancement in the field lies in delicate control over the reaction and obtaining high-growth-rate synthesis of non-defective SWCNTs. Here, we investigate the aerosol synthesis of SWCNTs implementing dual hydrocarbon feedstocks (ethylene and toluene) in pursuit of achieving advanced control over nanotube growth and overcoming performance-productivity trade-off. We evaluate the effects of particular growth parameters on nanotube structural characteristics, discussing the routes for synthesis condition optimization and providing a critical assessment of the used method. As a result, we demonstrate the synthesis of highly conductive SWCNT films (sheet resistance of 57 Ω/◻ at 90% transmittance after gold-chloride doping) at elevated yield, significantly reducing the performance-productivity trade-off (4). The multiparametric nature of the experimental data is also used in the comparative analysis of machine-learning algorithms and their capability to predict characteristics of produced SWCNTs from synthesis conditions. An artificial neural network-based approach is demonstrated to provide the most efficient data fitting, especially for highly nonlinear parameters such as film conductivity. We believe our work to guide the path for the advanced performance of nanotube-based transparent conductive films and facilitate the targeted production of SWCNTs. References 1. A. Kaskela et al., Nano Lett. 10, 4349–4355 (2010). 2. D. Mitin et al., ACS Appl. Mater. Interfaces. 12, 55141–55147 (2020). 3. K. Mustonen et al., Appl. Phys. Lett. 107, 1–6 (2015). 4. E. M. Khabushev et al., Carbon N. Y. 189, 474–483 (2022).

Resume : Nanostructuring of carbon nanomaterials by energetic ion beam is very promising topic of research. When energetic ions pass through localized region, it deposited energy in its passage which locally modify the materials properties. In the present experiment, we irradiate Bilayer graphene and graphene oxide samples with ion beams of different energy and fluences. Raman measurement is done before and after ion irradiation on graphene sample and intensity ratio of D and G Raman peak is plotted with fluence. Raman defect analysis on irradiated graphene samples suggested a threshold fluence for amorphization. The contribution from electronic and nuclear stopping in damage production is discussed. In case of graphene oxide reduction is reported with increasing fluence which is further correlated with electronic and nuclear stopping power.

Resume : The dielectric/electric properties of composites with various magnetic nanoparticles like Ni@C (carbon-coated Ni)/epoxy composites and Ni@C/MWCNTs (multi-walled carbon nanotubes)/epoxy composites loaded with fixed MWCNTs amount just below percolation threshold (0.09 vol.%) and Ni@C at different concentrations up to 1 vol.% were investigated in broad frequency (20 Hz–40 GHz) and temperature (30 K–500 K) regions. In composites with the only Ni@C nanoparticles the electrical percolation threshold was determined between 10 and 15 vol.%. Above the percolation threshold the dielectric permittivity (ε') and the electrical conductivity (σ) of the composites loaded with Ni@C only are high enough, i.e. ε'=105 and σ=0.6 S/m at 100 Hz for composites with 30 vol.% Ni@C, to be used for electromagnetic shielding applications. The annealing to 500 K was proved to be an effective and simple tool to decrease the percolation threshold in epoxy/Ni@C composites. For hybrid composites series an optimal concentration of Ni@C (0.2 vol.%) was determined, leading to the conductivity absolute values several orders of magnitude higher than that of a composite filled with MWCNTs only. The synergy effect of using both fillers have been discussed. Below the room temperature the electrical transport is mainly governed by epoxy resin compression in all composites, while the electron tunneling was observed only in hybrid composites below 200 K. At higher temperatures (above 400 K), in addition to the nanoparticles redistribution effects, the electrical conductivity of epoxy resin makes a significant contribution to the total composite conductivity. The dielectric relaxation spectroscopy allows estimating the nanoparticle distribution level in polymer matrix and could be used as non-destructive and fast alternate to microscopy techniques for general polymer composite fabrication control.

Resume : Laser processing of nanocarbon films emerges as the preferred technique to prepare carbon-based electrodes. A great effort focuses on exploiting this fast, sustainable, and cost-effective method on a broader range of nanomaterials. This study describes the laser-induced production of reduced graphene oxide with carbon nanotube (rGO/CNT) composites and their application as flexible electrodes. Conductive carbonized films were imprinted on a flexible substrate by CO2 laser (10.6 μm). The composites formation is supported by a detailed microstructural and chemical analysis, which confirms the structural integration of rGO with CNTs. Electrodes containing CNTs exhibit 7.5-fold increase in conductivity compared to only rGO electrodes. Importantly, when the electrodes are bent, the conductivity retention of the composite is significantly superior compared to the only rGO electrodes. Upon bending, the change in conductivity is lowered from 0.62 to 0.19. Furthermore, when used as electrodes in flexible supercapacitor devices, the composites with CNTs show 98.45 % retention in specific capacitance while maintaining structural integrity. In contrast, rGO electrodes without CNT addition deform upon bending and retain only 63.88 % of the relaxed specific capacitance.

Resume : The technique for layer-resolved Raman mapping is an extension of the previously introduced method of determining the number of graphene layers [1]. It’s based on the substrate’s Raman-active modes intensity attenuation, caused by graphene absorption. Combining this method with the standard Raman analysis [1,2] allows the standardization of the material regardless of the number of graphene layers. This method is presented in the example of transferred graphene, decomposed into the areas of single and multiple graphene layers and characterized separately by standard Raman analysis. The research leading to these results has received funding from the National Science Centre, Poland under Grant Agreement No. OPUS 2019/33/B/ST3/02677 for project ‘‘Influence of the silicon carbide and the dielectric passivation defect structure on high-temperature electrical properties of epitaxial graphene’’ and the National Centre for Research and Development, Poland under Grant Agreement No. LIDER 0168/L-8/2016 for the project ‘‘Graphene on silicon carbide devices for magnetic field detection in extreme temperature conditions’’. [1] A. Dobrowolski, J. Jagiello, D. Czolak, T. Ciuk, Physica E: Low-dimensional Systems and Nanostructures, 134, 114853 (2021) [2] K. Pietak, J, Jagiello, A. Dobrowolski, R. Budzich, A. Wysmołek, T. Ciuk, Applied Physics Letters, 120, 063105 (2022)

Resume : Two-dimensional (2D) layered transition metal dichalcogenides (TMDCs), particularly molybdenum disulfide (MoS2), with exceptional optical and electrical characteristics and a tunable bandgap, open up new opportunities for next-generation electronic devices. The direct growth of MoS2 onto the dielectric substrates by chemical vapor deposition (CVD) is a convenient way for photodetector fabrication. However, the electrical performance of the photodetector is limited by residual tensile strain resulting from the high?temperature growth of MoS2 film and contamination at the MoS2/growth substrate interface caused by the growth process. Here, we present a quasi-dry layer transfer technique for transferring MoS2 to a fresh, identical substrate that overcomes these limitations. Using the same fabrication process, we fabricate two photodetector devices, one on CVD-grown trilayer (3L) MoS2 and the other on transferred 3L MoS2. We observed that the current in the transferred MoS2 photodetector is substantially larger (100 times) than in the CVD-grown photodetector. Also, after the transfer, the photo-to-dark current (PDCR), responsivity, and detectivity were all enhanced by 12, 100, and 10 times, respectively. The device shows maximum responsivity of 0.072 A/W. The significant enhancement in the photoresponse of the device showed the improved electrical properties of the transferred film. Furthermore, the superiority of the quasi-dry transfer process over conventional wet transfer methods has also been confirmed by optical and electrical characterizations. The photodetectors based on the proposed transfer process offer ultralow cost, rapid fabrication, and large-scale manufacturing capacity without detrimental effects on humans or the environment. In addition, the quasi-dry transfer process can be used to fabricate 2D/2D or 2D/3D heterostructures and flexible electronic devices. This method may also be used to transfer other 2D materials such as graphene, WS2, MoSe2, etc.

Resume : Lasers are used in many fields such as healthcare, industry, laboratory research, military, and communications. However, intense laser light exposure can cause injuries to the human eye and can damage sensitive detectors. Novel technologies against laser risks are the ground for researching a new class of materials to implement switching devices and self-activating optical limiters able to guarantee fast response and reset times. The design of such devices requires the combination of thin-film multilayers made up of a metallic film and a phase-change material (PCMs), namely Vanadium Dioxide (VO2). The interest in VO2 depends on its properties. In particular, it shows a first-order reversible insulator to metal phase transition (IMT) at about 67°C accompanied by a structural phase transition inducing remarkable changes in electrical and optical properties. Despite the wide range of techniques used to grow VO2, it is challenging to achieve a pure phase, especially in thin films. Magnetron sputtering is the most used method thanks to its advantages of controllable film thickness, low temperature, and great industrial potential. Our research –carried out in the framework of the OPTIMIST project, funded by NATO through the Science for Peace and Security (SPS) Programme –aims to design a multilayer device of Ag and VO2 films on sapphire by magnetron sputtering and to obtain the optimal working configuration by numerical simulations. The growth process is adapted to obtain a pure VO2 phase by a room temperature deposition followed by annealing treatment at 550°C in a vacuum. The Raman characterization reveals the presence of the VO2 film and the hysteresis cycle, obtained with temperature-dependent resistance measurements, revealed the IMT transition. Once the optimal growth parameters of VO2 are obtained, a layer of silver is deposited between the VO2 and the sapphire substrate to control the threshold power at which the transition occurs. Finite element method (FEM) simulations are used to study the device dynamics to corroborate the experimental results and to find multilayer configurations with optimal performance in terms of speed and modulation depth.

Resume : Nowadays novel two-dimensional (2D) structures attract scientific interest due to their high surface area, unique chemical and optical properties, and high range of the material combination. Our focus of interest falls on the noble metal nanoparticles array demonstrating surface lattice resonance (SLR) seen as peaks in the optical absorbance spectra [1]. Its plasmonic properties highly depend on the periodicity of the array and the size of the noble metal structures [2]. The tunability of the 2D nanostructures’ optical properties opens new prospects for the substrates application for SERS. The capillary assisted particle assembly (CAPA) technique is used for the heterogeneous integration of micro-and nanoscale objects on a variety of surfaces [3]. We have previously shown the efficient use of CAPA for the fabrication of 2D structures characterized by the SLR effect by deposition of noble metal nanoparticles on trapped PDMS substrate [4]. Such a technique can be applied for the fabrication of SERS substrates with tunable optical properties adjusted to the excitation laser wavelength. In the present work, the chemically synthesized silver nanoparticles with mean diameter from ~40 nm to ~80 nm were deposited on the 330 nm periodicity trapped PDMS template by CAPA. The influence of the nanoparticle size variation on the SLR peak position was shown and adjusted to a higher percentage of overlapping with the 532 nm excitation laser wavelength to get the maximum sensitivity of SERS substrates. SERS measurements were done using 2-naphthalenethiol target molecule and the detection limit was determined for 10-8M concentration whereas the calculated enhancement factor (EF) reached 2.8·109. The effect of the number of nanoparticles per trap on the EF was studied as well. The combination of the template periodicity, particle size and particle number per trap allows us to tune the optical response of the 2D nanostructured substrate for specific laser excitation wavelengths. References: [1] Kravets, Vasyl G., Andrei V. Kabashin, William L. Barnes, and Alexander N. Grigorenko. "Plasmonic surface lattice resonances: a review of properties and applications." Chemical reviews 118, no. 12 (2018): 5912-5951. [2] Du, Yuchan, Lina Shi, Meihua Hong, Hailiang Li, Dongmei Li, and Ming Liu. "A surface plasmon resonance biosensor based on gold nanoparticle array." Optics Communications 298 (2013): 232-236. [3] Ni, Songbo, Lucio Isa, and Heiko Wolf. "Capillary assembly as a tool for the heterogeneous integration of micro-and nanoscale objects." Soft Matter 14, no. 16 (2018): 2978-2995. [4] Juodėnas, Mindaugas, Domantas Peckus, Tomas Tamulevičius, Yusuke Yamauchi, Sigitas Tamulevičius, and Joel Henzie. "Effect of Ag nanocube optomechanical modes on plasmonic surface lattice resonances." ACS photonics 7, no. 11 (2020): 3130-3140.

Resume : Van der Waals materials have gained increasing interest in recent years, with a huge number of proof-of-concept devices shown for electronics and optoelectronics [1]–[3]. These are generally manufactured from mechanically exfoliated flakes, which suffer from stochastic positioning and micrometric sizes. The re-shaping of 2D materials opens interesting possibilities for tailoring electronic and optoelectronic properties, as well as it enables the fabrication of devices with optimized geometries. State of the art nanopatterning of exfoliated flakes is generally obtained by localized chemical etching [4] which, although effective for creating single demonstrative configurations, are not suitable for fabricating scalable devices for real-life applications. Starting from these premises, we developed a novel approach for creating molybdenum disulfide (MoS₂) nano-circuits through an additive approach based on MoS₂ deposition via ion beam sputtering coupled to thermal Scanning Probe Lithography (t-SPL) [5]. Accurate manipulation of a hot silicon nanoprobe (radius ∼10nm) allows to write a mask onto a sacrificial polymer layer: the sharp tip, transiently heated by Joule effect, efficiently removes the polymer film in selected nanometer scale areas. We deposit a few-nm thick MoS₂ precursor film on the nanopatterned substrates via a custom-made deposition system based on ion beam sputtering. After lift-off, we obtain the confinement of well-defined MoS₂ nano-paths, which subsequently can be recrystallized by high temperature annealing in presence of a sulfur atmosphere, to avoid stoichiometric changes. The resulting 2D nanopatterns are resolved at the nanometer level and show clear spectroscopic features (excitonic and vibrational) characteristic of 2H-MoS₂ semiconducting phase. We finally exploit the direct overlay approach of the t-SPL Nanofrazor technology to write Au/Ti metal electrodes directly above our MoS₂ nano-circuits. This configuration allows us to investigate the electronic properties of the MoS₂ nanopatterns via Kelvin Probe Force Microscopy (KPFM) and conductive–AFM. These latter measurements are sensitive to electronic work function and to electrical transport on a nanometer scale, showing that the MoS₂ nanocircuits are a suitable platform for semiconducting interconnections in 2D-TMD integrated electronic and optoelectronic devices. In conclusion, we demonstrate a novel route for the arbitrary growth and patterning of TMDs at the nanoscale, which represents an enabling technology for the future fabrication of in-series devices based on 2D semiconducting Van der Waals materials. [1] Wang, Q. et al., Nature Nanotech. 7, (2012). [2] C. Martella et al., Adv. Mater., 2018, 30. [3] M. Bhatnagar et al., Nanoscale, 2020, 12. [4] Stanford, M.G., et al., npj 2D Mater. Appl. 2, 20 (2018). [5] M.C. Giordano et al, « Thermal Sculpting of 2D TMD semiconducting nanocircuits at wafer scale», under submission, Department of Physics, University of Genova, 2022.

Resume : The formation of multiple morphologies and patterns in a controlled fashion is crucial for advancing various technologies such as sensing and photonic applications. Yet, the conventional approach for the fabrication of multiple nanoscale morphologies relies heavily on the development of complex, multi-step lithography processes, which are both expensive and time consuming. We have previously demonstrated a simple approach for obtaining dual patterns in block copolymer films using topographically defined substrates featuring arbitrary shapes [1]. Different surface patterns develop on the plateaus and in the trenches owing to slight differences in the local film thicknesses, to which the morphology in ultrathin films is highly sensitive. In this work we expand the investigation of the influence of the substrate topography on the morphologies and discuss the role of the film profile at the edge of the plateau on nucleating microphase separated domains near the plateau edges, where their existence or absence further dictates the morphology on the plateau regions [2]. Analysis of local morphologies and height contrasts developed on numerous substrates featuring different plateau and trench widths and trench depths enabled the construction of a phase diagram for each region, which relate the local patterns to the height contrast and the fraction of film that resides in the trenches. We have identified linear relationships that enable one to determine the height contrast and fraction of the film in the trench directly from the dimensions of the topographic features of a given substrate. Using the phase diagrams, one can thus predict the local patterns that would develop on the plateaus and in the trenches directly from the substrate parameters. These insights were applied to a different type of block copolymer, attesting to the generality of the assembly principles identified. This block copolymer allowed the formation of gold nanoparticle superstructures with 4 types of dual patterns [3]. Preliminary results show the potential of such structures to serve as ultrathin polarizers. References [1] E. Michman, M. Langenberg, R. Stenger, M. Oded, M. Schvartzman, M. Müller, R. Shenhar ACS Appl. Mater. & Interf. 2019, 11, 35247-35254. [2] E. Michman, M. Oded, R. Shenhar Polymers 2022, in press. [3] N. Eren, O. Burg, E. Michman, I. Popov, R. Shenhar Polymer 2022, 245, 124727.

Resume : Two-dimensional layered semiconductors are promising candidates for applications in electronics and optoelectronics. For an effective exploitation of their functional properties, it is also important to understand their thermal behaviour. An important issue is how to measure their heat diffusion properties, especially when they are in contact with different materials, such as insulators or metal interconnects. In this work we use Raman spectroscopy to investigate how the laser-induced heat affects the phonon modes at the interface by comparing the experimental data with a finite element simulation of a localized heat diffusion, trying to tackle also the measurement of the interface thermal resistance at the nanoscale. The case studies presented are the heat dissipation on Au-supported black phosphorus nanosheets and Ag-supported silicene and silicene/stanene stacks. [E. Bonera and A. Molle, Nanomaterials 2022, 12(9), 1410] [E. Bonaventura et al., submitted]

Resume : Mixed-dimensional heterostructures are emerging to be very promising for the future electronic and optoelectronic applications. Here, we report on the fabrication and characterization of a 2D/3D vertical van der Waals p-n heterojunction based on p-type gallium selenide (GaSe) and n-type gallium oxide (Ga_2 O_3). Kelvin Probe Force Microscopic (KPFM) measurements have been conducted to estimate the difference in the surface potential values between GaSe and Ga_2 O_3, which is further used to find out the conduction band offset value at the GaSe/Ga_2 O_3 hetero-interface to design the band diagrams. The current-voltage measurements on the device display a diode-like behavior which is attributed to the type-II band alignment, present at the p-n junction interface as per the electron affinities and bandgap values of GaSe and Ga_2 O_3. The device exhibits a high current rectification ratio of ~2500 extracted at ± 5 V. The photoresponse properties of the heterostructure are also studied and the figure of merit parameters of the photodetector such as photoresponsivity and specific detectivity have been evaluated for the fabricated device. Since the GaSe/Ga_2 O_3 heterojunction holds a great potential in the field of efficient optoelectronic devices, we believe our study could pave the way to designing innovative optoelectronic devices by integrating low-dimensional materials with conventional 3D semiconducting materials.

Resume : Aqueous suspensions of inorganic/mineral nanosheets displaying liquid crystalline properties have recently received much interest for applications in naoelectronics and nanophotonics. Beyond graphene and other van der Waals materials, larger surface density 2D materials are also investigated such as H3Sb3P2O14, which is easily exfoliated into individual nanosheets that can self-assemble to form the first known lamellar phase based on covalent nanosheets [1, 2, 3]. Remarquably, this mesophase presents an hyperswelling behaviour in water, with observed lamellar distances above 200 nm, hence enabling light diffraction that can be tuned by various mechanism [4] and that has been used for the making of chemical sensors [5]. We will report on our unpublished study of the nanosheets restaking, which enables the making on the influence of the counter ion in the phase H3(1-x)M3xSb3P2O14 (M = Li, Na, K, Rb, Cs), and on the highly ordered crystalline materials that can be obtained following the restacking induced such cation exchanges. Keywords: Photonic Crystals, 2D nanosheets, restacking, highly ordered materials [1] Davidson, P.; Penisson, C.; Constantin, D.; Gabriel, J.-C. P. Isotropic, Nematic, and Lamellar Phases in Colloidal Suspensions of Nanosheets. Proc. Natl. Acad. Sci. U. S. A. 2018, 115 (26), 6662–6667. [2] Gabriel, J. C. P.; Camerel, F.; Lemaire, B. J.; Desvaux, H.; Davidson, P.; Batail, P. Swollen Liquid-Crystalline Lamellar Phase Based on Extended Solid-like Sheets. Nature 2001, 413 (6855), 504–508. [3] Davidson, P., and Gabriel, J.C.P. Mineral liquid crystals. Current opinion in colloid & interface science 2005, 9 (6), pp.377-383. [4] El Rifaii, K., Wensink, Goldmann, C., Michot, L., Gabriel, J.C. P., Davidson, P. Fine Tuning of the Structural Colors of Photonic Nanosheet Suspensions by Polymer Doping. Soft Matter 2021, 17 (41) 9280-9292. [5] Szendrei, K., Ganter, P., Lotsch, B.V. Selectivity, cycling stability and temperature dependence of touchless finger motion tracking devices based on 1D photonic crystals. Photonic Crystal Materials and Devices XII 2016, 98850Z.

Resume : Several two-dimensional (2D) van der Waals (vdW) magnetic materials have been recently developed and extensively investigated along the route for robust commercial nanoelectronic devices. Among them, iron germanium tellurides FexGeTe2 (FxGT) with x = 3 – 5 have been considered as promising candidates. F3GT is a very well studied metallic ferromagnet, in which a long-range ferromagnetic (FM) order has been confirmed experimentally and it hosts topologically protected spin textures known as skyrmions [2]. The less studied F5GT is considered as an itinerant long range ferromagnet (FM) [3] and it has Tc at room temperature [4], [5]. In the present work, epitaxial Fe5-xGeTe2 (FGT) FM /Bi2Te3 topological insulator (TI) heterostructures were grown by Molecular Beam Epitaxy (MBE) on insulating substrates and with the long term goal to investigate the charge to spin conversion due to Rashba-Edelstein effect originating from the TI surface states. FGT/Pt (or Al) heterostructures were also prepared for comparison. Two different series of FGT film thickness were grown in order to investigate the effect of thickness. The structural properties of films were characterized by X-ray diffraction (XRD) and in situ by reflection high energy electron diffraction (RHEED). The magnetic properties were investigated using Magneto-optical Kerr (MOKE) microscopy/magnetometry and SQUID magnetometry. According to RHHED patterns and XRD, it is confirmed the high quality of epitaxial films and their expected crystal structure and composition. Magnetometry results reveal that the growth of Bi2Te3 TI on FGT films significantly enhances the Tc well above room temperature, which correlates with the interfacial exchange interactions. In comparison with the almost negligible magnetization for the FGT/Pt (or Al) heterostructures above room temperature, FGT/Bi2Te3 heterostructures present a stabilized in plane magnetization. The investigation of magnetic domain structure indicates a robust stripe like pattern even at room temperature. These outcomes suggest that FGT/Bi2Te3 TI heterostructures are suitable for spintronics applications. References [1] H.-J. Deiseroth et al., Eur. J. Inorg. Chem. 2006 (8), 1561−1567 (2006). [2] B. Ding et al., Nano Lett. 20, 868−873 (2020). [3] H. Zhang et al., Phys. Rev. B: Condens. Matter Mater. Phys. 2020, 102, 064417. [4] M. Ribeiro et al., npj 2D Mater Appl 6, 10 (2022). [5] L. Alahmed et al, 2D Mater. 8 2021, 045030.

Resume : The development of non-volatile memory, which can store a large amount of data long even after it was turned off, has become a hot topic in the era of big data. The ferroelectric tunnel junction (FTJ), a promising candidate for non-volatile memory, has a thin ferroelectric layer that allows for non-destructive readout and the ability to store data using ferroelectric polarization as in conventional ferroelectric random-access memory (FeRAM). Traditionally, FTJs have been studied based on perovskite oxides such as Pb(Zr,Ti)O3 and BaTiO3. However, these materials have incompatibility with the complementary metal-oxide-semiconductors (CMOS) process. Compared to conventional perovskite oxides, Hf0.5Zr0.5O2 (HZO) has many advantages. It is compatible with metals such as TiN and W, which is often used in CMOS processes. Also, it can even grow directly on silicon. For use in practice, FTJs require a sizable current scale which can be obtained from a thin thickness of less than 5 nm. However, HZO in ultrathin thickness shows a small remnant polarization value due to the weakening of the ferroelectric property. A low remnant polarization value causes the HZO-based FTJ to have a low tunneling electroresistance (TER) value. In this study, FTJ based on HZO was manufactured using PLD. It grew directly on high-temperature silicon without the additional annealing process required by the ALD process. In addition, a very thin SrTiO3 (STO) dielectric layer is deposited between HZO and silicon to relieve leakage current in the HZO, showing the sizable current scale and TER values.

Resume : Lepidopteran scales exhibit exquisite architectures that produce complex optical performance, such as structural colors for multiple survival strategies. However, how do these optical properties evolve to achieve such an excellent performance remains enigmatic because of the rarity of fossils and complexity of the gene regulatory network. Here, inspired by the primitive lepidopteran fossils, we deduce that the morphology of these multilayered scales can be expressed by the basic trigonometric function sin(x)=t. We developed a unified evolving model (UEM) to reconstruct the evolutionary process from original multilayers to the current lepidopteran scale microstructures. The simulated optical response results show that factors such as the light absorption, warning coloration, and visual range intensity were optimized for survival by these insect individuals. Our UEM provides a route to rationalizing other natural periodic microstructures. Furthermore, microstructure parameterization can facilitate the design of the nano-optical materials. Corresponding results can help develop specific applications such as photothermal conversion, radiative cooling, and camouflaging.

Resume : Metallic micro-and nanostructures have received exceptional attention during the last decades, due to their unique structural, electronic, and catalytic properties. Especially, the incorporation of these micro-and nanostructures with wide-bandgap metal oxide semiconductors such as titanium oxide (TiO2) and zinc oxide (ZnO) has been shown many times for various applications such as photocatalysis [1,2], water splitting, self-cleaning [3], sensing applications (surface-enhanced Raman spectroscopy (SERS)) [4]. In general, SERS is a well-known analytical technique for the detection of biocides and biomolecules, monitoring environmental pollution and toxicity, and identification of narcotics and explosives. Here, the substrate plays the most critical role in the performance. Therefore, the shape and orientation of metallic (usually plasmonic) nanostructures on the SERS substrate greatly affect the signal intensity and sensitivity since all these play a role in the interaction of light with the surface. Here, we propose a 4N-in-1 hybrid substrate concept (nanocolumnar structures, nanocrack network, nanoscale mixed oxide phases, and nanometallic structures) for ultra-sensitive and reliable photo-induced-enhanced Raman spectroscopy (PIERS). The use of the 4N-in-1 hybrid substrate leads to around 50-fold enhancement over the normal SERS, which is recorded as the highest PIERS enhancement up to date.

Resume : During the last three years, the coronavirus and its mutations caused a global upsurge in number of people being infected with COVID-19. Interestingly, a greater number of patients affected with mutated variations of COVID-19 are reported to be asymptomatic that increases the risk of infecting other people. In the wake of this situation, there is a need for prompt, large-scale, accurate and cost-effective screening detection of COVID-19 carriers of any genetic trait, to effectively trace symptomatic along with asymptomatic patients and isolate them, to stop the virulent spreading of the coronavirus and to gradually end the pandemic. Current biological based methods such as PCR tests require nearly 4 hours to obtain the result. Therefore, in this work, we propose a prompt, non-biological and effective testing solution, which can screen coronavirus infected patients within one minute, and segregate them from the healthy individuals, to be used at entry points. Our proposed method is based on the detection of shift in resonance frequency of a nano-gap LC-resonant metamaterial chip, caused by viruses and mainly related exhaled particles, when performing a terahertz (THz) spectroscopy. The chip consists of thousands of micro-antennas arranged in an array, and enclosed in a plastic breathalyzer-like disposable capsule kit. After reaching appreciable agreement between numerical simulations and experimental results using our metamaterial design, low scale clinical trials were conducted with asymptomatic, symptomatic coronavirus patients and healthy individuals. In our proposed coronavirus screening test with we detect a combination of viruses and related biological particles exhaled by an infected person, (e.g. virus debris, cytokines, cell debris and related proteins and fat molecules) which produces an effective change in dielectric constant of the resonant metamaterial at the capacitive gap regions. This phenomenon red shifts the resonance frequency (ΔF), which becomes the deterministic factor to effectively screen the infected patients from the healthy individual. We achieve a definite band of ΔF=1.5 GHz to 9 GHz for infected individuals, with a linear relationship of increasing ΔF with increasing viral load. In order to effectively differentiate between ‘healthy’ and ‘SARS-CoV-2 infected’ patients in terms of ΔF, we included only ‘completely healthy’ and ‘sick of SARS-CoV-2’ individual, in order to design a screening test only and not a diagnostic test. The simplicity of this cost-effective breathalyzer-based testing kit lies in its ease of handling, which does not require a complex setup procedure. The entire testing and analysis are performed within 50 to 55 seconds, with 86.84% agreement with the RT-qPCR analysis (with both PPV and NPV values of 88.88%), based on the law scale verification clinical trials conducted at Soroka medical centre, Israel. Reference: 'Terahertz Impedance Spectroscopy of Biological Nanoparticles by a Resonant Metamaterial Chip for Breathalyzer-Based COVID-19 Prompt Tests', Rudrarup Sengupta, Heena Khand, and Gabby Sarusi, ACS Applied Nano Materials 2022 5 (4), 5803-5812, DOI: 10.1021/acsanm.2c00954.

Resume : Here, we report detection of hemozoin, a metabolic byproduct of malaria parasite exhibiting paramagnetic properties using magnetic surface enhanced Raman spectroscopy (M-SERS). The SERS active silver nanorods were deposited over neodymium magnetic substrates (0.3 T) kept at 120K temperature using glancing angle deposition technique. Magnetic field augmented SERS measurements were performed for hemozoin on these M-SERS substrates and AgNRs deposited over glass (conventional SERS) substrates in presence of an external magnetic field (0.3 T). The SERS signal intensity was found to be enhanced by ten-fold compared to the measurements performed on the conventional SERS substrates in the absence of any magnetic field. The presence of high spin trivalent iron in hemozoin structure led the magnetic field induced agglomeration of these molecules in vicinity of the electromagnetic ‘hotspots’ available on the SERS substrates which was confirmed by running Rigorous coupled wave analysis (RCWA) based simulations. These interactions lead to higher enhancement of vibrational modes of the porphine group directly linked to iron. The limit of detection of hemozoin for M-SERS was obtained as low as 10-11 M (< 10 parasites/µl) which can be employed for early stage malaria detection

Resume : The development of point-of-care (POC) testing platforms has increased during the COVID-19 pandemic due to their multiple benefits including low cost, rapid turnaround time, on-site testing, and minimal sample preparation [1-2]. Although POC tests are a good alternative to the gold standard technique (reverse-transcriptase-polymerase chain reaction, RT-PCR) for SARS-CoV-2 detection, there are challenges regarding their sensitivity and specificity that need to be addressed [3-4]. One strategy to improve the performance of POC is the integration of nanostructures as sensing elements [5]. In this work, we used interdigitated gold nanowires (Au NWs) in combination with electrical impedance spectroscopy (EIS) for the detection of the receptor-binding domain of the S1 protein of the SARS-CoV-2 virus and the respective antibodies that appear during and after infection. Our sensor system was composed of six sensing devices, each of these sensors containing six pairs of interdigitated gold nanowires of 120 nm in width. The surface of the Au NWs was functionalized with antigens or antibodies of SARS-CoV-2 so that the molecules of interest present in the sample can bind to them. The adhesion of molecules to the surface of the Au NWs modulates the physicochemical properties of the surface [6]. As a result, it was possible to correlate the changes in electrical impedance with the binding of specific analytes to the surface of the Au NWs using EIS. The developed sensing platform is an attractive system for screening during pandemics and can be adapted for the detection of relevant target-analyte pairs in different diseases. References [1] E. Valera et al., “COVID-19 Point-of-Care Diagnostics: Present and Future,” ACS Nano, vol. 15, no. 5, pp. 7899–7906, 2021, doi: 10.1021/acsnano.1c02981. [2] E. Morales-Narváez and C. Dincer, “The impact of biosensing in a pandemic outbreak: COVID-19,” Biosens. Bioelectron., vol. 163, p. 112274, 2020, doi: https://doi.org/10.1016/j.bios.2020.112274. [3] W. Leber, O. Lammel, A. Siebenhofer, M. Redlberger-Fritz, J. Panovska-Griffiths, and T. Czypionka, “Comparing the diagnostic accuracy of point-of-care lateral flow antigen testing for SARS-CoV-2 with RT-PCR in primary care (REAP-2),” EClinicalMedicine, vol. 38, p. 101011, 2021, doi: 10.1016/j.eclinm.2021.101011. [4] I. Wagenhäuser et al., “Clinical performance evaluation of SARS-CoV-2 rapid antigen testing in point of care usage in comparison to RT-qPCR,” EBioMedicine, vol. 69, pp. 1–7, 2021, doi: 10.1016/j.ebiom.2021.103455. [5] N. Wongkaew, M. Simsek, C. Griesche, and A. J. Baeumner, “Functional Nanomaterials and Nanostructures Enhancing Electrochemical Biosensors and Lab-on-a-Chip Performances: Recent Progress, Applications, and Future Perspective,” Chem. Rev., vol. 119, no. 1, pp. 120–194, 2019, doi: 10.1021/acs.chemrev.8b00172. [6] J. L. Hammond, N. Formisano, P. Estrela, S. Carrara, and J. Tkac, “Electrochemical biosensors and nanobiosensors,” Essays Biochem., vol. 60, no. 1, pp. 69–80, 2016, doi: 10.1042/EBC20150008.

Resume : Bacteriophages (phages for short) are viruses whose host organisms are bacteria. Different bacteriophage types are abundant with many shapes and properties. One of the essential advantages of phages is their high specificity. A specific type of bacteriophage can attack single specie or even a strain of bacteria. Thus, choosing a bacteriophage that selectively targets given bacteria is always possible. Additionally, there are robust phages that retain their activity even after exposure to high temperatures and organic solvents. Unlike antibodies, phages can be easily and cheaply produced in large quantities. By simply infecting a bacteria solution, one can obtain a large number of progeny phages. Among phages, there are ones that are regarded as a great model for studies on human, often pathogenic, viruses Viruses are both our enemies and, surprisingly, allies, depending on the point of view and specific situation. We need to fight against virions (virion – single viral particle; the body of virus) when they are causing diseases or sabotaging biotechnological based industry processes. However, viruses are our allies as the main component of vaccines, therapies against “superbugs” or novel agents for biosensors. Here, we show examples of both approaches realized in the framework of materials science, nanotechnology, and physical chemistry. The research was performed within Sonata Bis grant 2017/26/E/ST4/00041.

Resume : Nanomaterials sciences show an increasing interest in bottom-up synthesis of functional structures based on plant virus as 3D nanoscale templates, to biomimetically synthetize complex functional nanostructures with remarkable physicochemical properties and a wide variety of applications: catalysis, energy conversion, and especially nanomedecine and biology because of their lack of pathogenicity in humans and animals [1]. Because of their well-defined and highly organized symmetric structures, high robustness over wide ranges of temperature, pH, buffer, and in the presence of organic solvents, viral capsid proteins then provide a 3D scaffold for the precise placement of plasmon materials yielding hierarchical hybrid materials [2]. Two ways are possible to obtain plasmonic nanostructure onto capsid: grafting pre-formed nanoparticles or biomineralization. In this work, we decorated the capsid of tobacco mosaic virus (TMV) and potato virus X (PVX) with gold nanoparticles by biomineralisation, in order to construct plasmonic material assemblies in vitro and under mild conditions. TMV is one of the most exploited plant viruses in nano-bio-technology and its use for biomineralisation of nanoparticles is widely documented, [2] however questions about the mechanisms remain. We propose to answer these questions using liquid cell transmission electron microscopy (LCTEM), which allows an in situ study of dynamic processes in solution. The ex situ biomineralisation protocol is reproduced identically in the liquid cell. A systematic comparison of the results obtained between the beaker and the cell is made to ensure the robustness of the results. [1] (a) Capek, I. Adv Colloid Interface Sci. (2015), 222, 119-134. (b) Culver, J.N.et al. Virology (2015), 479-480, 200-212. (c) Li, F.& Wang, Q. Small (2014), 10, 230-245. (d) Liu, Z.et al. Chem Soc Rev 2012, 41, 6178-6194. [2] Lee, K. Z, Pussepitiyalage, V. B. Lee, Y.-H. Loesch-Fries, S. Harris, M. T. Hemmati, S. Solomon K. V. Biotechnol. J. (2021), 16, 2000311

Resume : Surface-enhanced Raman spectroscopy (SERS) has tremendously improved the detection and diagnostic tools for analysing of chemicals and biomolecules at trace levels. Any spectroscopic technique like IR, fluorescence, and Raman spectroscopy is effective in extracting molecular electronic, vibrational, and rotational energy levels. Raman spectroscopy is gaining popularity as it offers a real-time and non-destructive method of detection with no sample preparation requirement. The inherent weak Raman signal can be enhanced using the SERS technique, discovered by Fleishman et al. in 1977. In SERS, silver (Ag) or gold (Au) nanostructures can trap the incident electric field, exhibiting localised surface plasmon resonance. The resonance condition is achieved if the frequency of coherent oscillations of metallic nanoparticles (plasmons) matches the incident laser frequency. An enhanced incident electric field (~108-1012) will be locked in a minimum volume on the nanostructure surface, called hotspots. The shape anisotropy, spatial regularity, and sharp edges contribute to a more significant electric field localisation for the hotspot formation. Several nanofabrication tools have been developed to produce anisotropic, ordered nanostructures to get a sensitive and reproducible SERS substrate. Lithographic methods such as electron beam lithography (EBL), nanoimprint lithography, etc., produce regular nanostructures with controlled spacing. However, lithography is time-consuming, and it requires expensive equipment. Hence, the traditional lithography techniques are not suitable for the generation of structured nano-surfaces at a low cost on commercial scale. Thus, scientists have fabricated stable and ordered nanostructures using other alternatives like the glancing angle deposition (GLAD) method, self-assembly method, template-assisted deposition method, etc. However, these alternative techniques require a high vacuum chamber or complex fabrication steps. Instead, the texturing of Si wafer using wet chemical etching technique offers a large-area, three-dimensional micro and nano fabrication of various shapes that includes wire, pyramid, inverted pyramid, etc. In particular, the fabrication of Silicon nanowire has been exclusively popular in different optoelectronic applications for its enhanced electrical and optical properties. A lot of previous work in this field has reported the fabrication of Si nanowire using metal-mediated vapour-liquid-solid (VLS), physical vapour deposition (PVD), metal-assisted chemical etching (MACE), chemical vapour deposition (CVD), etc. The MACE process is especially popular because it allows large-area Si nanowire manufacturing without expensive vacuum chambers and instruments. MACE offers a facile, controllable, large-area fabrication method at a low cost. MACE also generates a high-crystalline, homogeneously produced Si NW structure with a large aspect ratio. This paper briefly demonstrates a lithography-free, facile two-step MACE fabrication method to produce Ag decorated Si nanowire. The fabrication of Ag decorated SiNWs were performed for different etching times. The fabricated substrate was optimised for maximum SERS performance considering 1 micromolar (10-6 M) concentration of R6G molecule. The MACE method has three essential requirements: 1. HF as a complexing agent; 2. Ag nanoparticles for catalysis; and 3. an oxidant (H2O2) with a higher reduction potential than silicon. The decoration of Ag on Si NW is required for exploring the plasmonic property of Ag nanostructure in SERS applications. The preparation of two-step MACE includes the following steps. A P-type Si wafer, having a < 100> crystal orientation was cleaned ultrasonically using acetone, isopropanol, and deionised (DI) water and was placed in a buffer HF solution to remove the native oxide (SiO2) layer. The two-step fabrication process of Ag deposited Si NW was done as follows. The wafers were dipped in a mixture of hydrofluoric acid (HF) and silver nitrate (AgNO3) solution of inside a Teflon beaker. The wafers are immediately washed in DI water to remove extra Ag ions and placed in an etchant solution of HF, H2O2 and DI water for 60 mins, 75 mins, and 90 mins, respectively. The Ag coated etched Si wafers were treated using a 50% nitric acid (HNO3) solution. The wafers were placed in buffer HF for oxide layer removal. Finally, the wafers were thoroughly washed with DI water and dried in N2 gas. Thus, Si nanowires are formed homogeneously with a high aspect ratio. To further decorate the formed Si NW with Ag, the Si wafers were dipped in another fresh solution of HF and AgNO3. The fabrication technique results in Si NW of a high aspect ratio for different etching times. As the etching time is increased, the length of a nanowire is increased. In conclusion, a facile fabrication of Ag decorated Si NW by MACE technique is achieved. The fabrication method allows scalable, lithography free, regular Si nanowire templates offering site-specific decoration of Ag nanoparticles. The optimised Ag nanostructure produces hotspots for the maximum enhancement of the Raman signal. The optimised SERS substrate can detect up to 10-12 M concentrations using a portable Raman spectrometer. Thus, the optimised SERS substrate offers a cost effective solution for real time, onsite detection of hazardous and toxic chemicals.

Resume : Organic solar cell based on Bulk Heterojunction (BHJ) have received great attention owing to its ease of processing and high-power conversion efficiency. However, controlling the morphology of Donor/Acceptor blend to enhance the device performance is challenging in case of one-step BHJ film formation. The process of charge separation and collection is complex for BHJ films and depends on the condition of film preparation and annealing. On the other hand, the sequential deposition of Donor and Acceptor phase enables better control over morphology and charge transfer. However, the conventional deposition methods like spin coating poses the threat of washing-off the underneath layer and hence require usage of orthogonal solvents or solvent mixture. The challenge in sequential deposition can be overcome by ultrasonic spray deposition process as it enables Layer-to-Layer (L2L) deposition of films. Here, Donor (P3HT) and Acceptor (PC71BM) materials, dissolved in Chlorobenzene, have been deposited sequentially via ultrasonic spray deposition for Active layer preparation. This results in quasi-planar heterojunction due to simultaneous wetting of first layer (Donor material) surface by spray deposited second layer (Acceptor material), leading to partial mixing of donor acceptor materials. This quasi-bi layer structure facilitates the exciton dissociation and charge transfer. The spray deposited quasi-planar heterojunction process provides an effective way of harnessing the advantages of both BHJ and planar heterojunction at the same time, along with being adequate for upscaling OSC devices for large-area application.

Resume : Graphitic carbon nitride (g-C3N4), an emerging 2-dimensional material analogous to graphene possesses a layered structure composed of tri-s-triazine motifs. It is bonded via weak Vander Waal forces and has tunable optoelectronic properties and excellent thermo-chemical stability. Owing to weak Vander Waal forces it can be synthesized into various nanostructures like nanosheets (NS), nanorods, quantum dots (QDs). These nanostructures render unique optoelectronic properties compared to their bulk counterpart making them suitable for optoelectronic devices either as interface layers or as an additive for active/ interface layer. In this work, we have incorporated the NS as a secondary dopant for the conventional PEDOT:PSS hole transport layer (HTL) and studied its effect on polymer solar cell performances. The addition of g-C3N4 NS found to modify the electronic properties of PEDOT:PSS via weakening of columbic interaction between PEDOT and PSS chains forming the expanded coil-like conformational structure. The optimized concentration of NS was 50 Vol%, enhancing the device efficiency by 40% compared to the undoped devices. This significant improvement in device performance can be attributed to higher Jsc and FF and reduced series resistance after doping. The formation of an expanded coil conformational structure after doping enhances the conductivity of the HTL. As a result of which it leads to better charge extraction and reduced recombination at the interface. This study demonstrates a novel strategy for improving polymer solar cell performances by modifying the HTL interface.

Resume : Chemodynamic therapy (CDT), which makes use of Fenton-type catalytic reactions to generate highly toxic hydroxyl radicals at tumor sites to trigger the apoptosis of the tumor cells, has emerged as a promising therapeutic strategy to treat cancers. The key requirement for its clinical translation is to achieve high Fenton catalytic efficiency at small doses. However, it is worth noting that simple general promotion of the Fenton reaction increases the risk of damaging normal cells besides the cancer cells. Therefore, a novel strategy to selectively enhance the Fenton reactivity in tumors by taking advantage of the characteristics of tumor microenvironment (TME) is highly demanded. A heterogeneous catalytic system based on Cu and Fe are capable of forming a highly efficient catalytic loop to meet all these criteria. We developed Cu-Fe peroxide nanoparticles (CFp NPs) that synergistically catalyzes the Fenton reaction in a TME-responsive way for selective and enhanced tumor therapy. The CFp NPs are targeted to tumor cells by the enhanced permeability and retention effect and decompose under the mildly acidic condition of TME to release free metal ions and H2O2. The released Cu and Fe ions, with larger portions of lower oxidation states, cooperatively boost the Fenton reaction and increase the levels of toxic hydroxyl radicals in tumors. Our results reveal that combing two different kinds of metal ions at an appropriate proportion can bring a significant improvement in the catalytic performance compared with the single-type metal ions. This is distinct from previous heterogeneous CDT systems in that the synergism is closely coupled with the Cu+-assisted conversion of Fe3+ to Fe2+ rather than their independent actions. This synergism occurs only in the mildly acidic condition of TME, thus an enhanced tumor-specific treatment is attainable with minimal deleterious impact on normal tissues. As a result, almost complete ablation of tumors at low doses is demonstrated without the aid of any other therapeutic modality. Furthermore, CFp NPs relieve hypoxia by producing O2 during the catalysis and exhibit a TME-responsive T1 magnetic resonance imaging contrast enhancement, both of which manifest the great potential of CFp NPs as a multifunctional theranostic agent for cancer treatment.

Resume : This paper describes how to detect damage caused by delamination of the constituent thin films of flexible organic light emitting diodes (OLEDs) used in medical device displays. Research and development of flexible devices using organic semiconductors that are attached to the human body to measure heart rate, EEG, and blood pressure are being conducted. The authors' group investigated the critical crack strain of OLED components and then proposed ways to improve the critical crack strain of layered OLED devices. However, flexible OLEDs not only crack due to tensile strain outside the curvature during bending, but also buckle peeling due to compressive strain inside the curvature. Therefore, in this study, we conducted a basic study for detecting the occurrence of buckling separation from the change in capacitance, targeting the metal electrode where buckling separation occurs. Specifically, a metal-coated polymer film is attached to a metal electrode using an ultrathin double-sided tape to form a capacitor, and the degree of peeling and the change in electric capacity are quantified by comparing calculated and measured values. As a result, it has been suggested that the delamination occurring in about 1% of the area of the size of 2 mm x 2 mm of the actual test piece can be detected. Furthermore, it was shown that the occurrence and progress of peeling can be quantitatively measured by measuring the capacitance of an organic semiconductor test piece simulating a flexible OLED during the repeated bending test.

Resume : Nanoparticle (NP) arrays of noble metals strongly absorb light in the visible to infrared wavelengths through resonant interactions between the incident electromagnetic field and the metal’s free electron plasma. Such plasmonic interfaces enhance light absorption and photocurrent in solar cells. We report here broadband plasmonic interfaces consisting of silver nanoparticles (NPs) formed by depositing by e-beam evaporation a thin film of Ag followed by dewetting process under thermal annealing. The NP interface yields a clear photocurrent enhancement (PE) in thin film silicon devices. For coatings produced from Ag NPs, an optimal value of 15% surface coverage (SC) was observed. Scanning electron microscopy of interface morphologies revealed that low SC is resulting in broadband PE; while at higher coverage, strings and clusters are formed and caused red shifting of the PE peak and a narrower spectral response. The multi-physics impacts of size and radius distribution of plasmonic-NPs (including Ag and Au) were also studied. For optimal PV performance, a parametric analysis was performed for system sizes of (3×3, 5×5, 7×7), and radii varying from 10 to 150 nm. Total spectral heat absorbed was also investigated by integrating total spectral heating from 300 nm to 1200 nm. The optimum performance for a Schottky-like device were obtained for a 70 nm radius and a surface coverage of 22.72 NP/µm2 , revealing a maximum short circuit current gain of about 47 % when compared to bare silicon solar cell.

Resume : Modeling of plasmonic solar cells (PSC) is critical for assessing the geometrical and operating conditions for optimized optical-electrical-thermal performance. For this purpose, a novel multi-physics model for plasmonic Schottky solar cell (PSSC), decorated with gold nanoparticles (Au-NPs) onto a thin silicon absorber, is developed. Notably, the modeling framework presented here is crucial for the solar cell field as currently no multi-scale multi-physics model is available for coupling optical, electrical, and thermal response of PSSC, simultaneously. The multi-physics influence of variable distribution of Au-NPs defined by size and radius is studied. For optimal electrical performance, parametric analysis is conducted for variable system sizes, namely (3×3, 5×5, 7×7), and radii of NP varying from 10 to 150 nm. Total spectral heat absorbed is obtained by integrating total spectral heating from 300 nm to 1200 nm. The optimum performance for a device, with 70 nm radius and 5x5 NPs array, revealed a maximum short circuit current gain of about 47 % when compared to bare silicon solar cell. However, this electrical boost is opposed by significant thermal gains in NPs, up to 182.5 %. Generally, a higher fraction of NP array and NP radius were found to increase the total spectral heating content. The developed framework may be universal as it is not only limited to monofacial configuration and Schottky solar cells, but could be extended and adapted to any other solid-state devices).

Resume : TiW alloy film is chemically stable and widely used inside semiconductor devices, mainly as buffer layers. We have suggested a feasibility of Zero-TCR (Zero - Temperature Coefficient of Resistivity) resistor on TiW alloy films formed by using sputtering in our previous papers [1]- [3]. We had been investigated ρ and TCR in TiW broadly binary alloy contents range and found the zero-cross point on TCR in Ti-rich alloy content side. On our previous research, the Zero-TCR TiW alloy was discovered by a low vacuum DC sputtering system equipped with an oil diffusion pump, however, the Zero-TCR had not been reproduced by a high vacuum RF sputtering system equipped with a turbo molecular pump. This time, we have discovered Zero-TCR point on Ti-rich TiW binary alloy by using the high vacuum sputtering system (reactive sputtering) introduced as appropriate with oxygen gas to Ar gas as a partial pressure. Oxygen-doped sputtering was focused on the Ti-rich side, where Zero-TCR is likely to appear. A base material for the reactive sputtering has been used with a pure Ti Target and W-wires put on the target. The most near zero TCR specimen has been obtained by 50% oxygen partial pressure on 95at% Ti content films by using this technique. [1] Y. Sakurai and T. Takeda, Abstract of E-MRS 2005 Fall Meeting. [2] Y. Sakurai, R. Nakajima, and H. Nakamura, Solid State Phenomena 154,175(2009) [3] Y. Sakurai, Y. Takeda, S. Ikeda, and Y. Sakamoto, physica status solidi (c), 11, 9-10, 1423(2014)

Resume : In recent years, oxide materials doped with rare-earth (REs) have attracted significant attention because they can be excited with infrared and ultraviolet light to produce red, green, and blue emissions [1–3]. Luminescent oxides are phosphors that possess higher physical and chemical stability than traditional luminescent materials based on sulfur and phosphorus. They are also interesting because they can be synthesized with low-cost methods, and most of them are not toxic [4]. The present work focuses on the synthesis and spectroscopic characterization of Eu-doped SrTiO3 ceramics, obtained by the sol-gel method, from stoichiometric quantities of high purity alkoxides. As a result of the thermal treatment, solid ceramic samples were obtained. To establish the phase composition, the crystallinity of the precursors, and purity of the final powders and related ceramics, X-ray diffraction (XRD) measurements were performed. A HITACHI S2600N scanning electron microscope (SEM) coupled with energy-dispersive X-ray spectroscopy (EDX) analyzed the ceramic samples microstructure and chemical composition. The grain size of the ceramics was determined as the mean intercept length by taking into account measurements on ∼60 grains and was 80nm. The luminescence properties of the perovskites are improved by increasing the europium concentration. The narrow bands in the luminescent spectrum of Eu3+ are sensitive to the crystallographic site symmetry occupied by Eu3+ ions. The electric dipole transition, 5D0→7F2, is allowed when Eu3+ is located at a noncentrosymmetric crystallographic site, while the 5D0→7F1 magnetic dipole transition comes from Eu ions in sites with inversion symmetry. Usually, the luminescence intensity ratio of 5D0→7F2 to 5D0→7F1, also called the asymmetry ratio, is considered a probe to detect the inversion symmetry around Eu3+ ions in the host [5]. This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS – UEFISCDI, project number PN-III-P1-1.1-TE-2021-1624 within PNCDI III and project 16N/08.02.2019 Program NUCLEU-LAPLAS VI. References: [1] Q. Liu et al., Spectrochimica Acta A: Molecular and Biomolecular Spectroscopy, vol. 87, 190–193, 2012. [2] Z. Xia et al., Journal of Materials Chemistry C, vol. 1, 37, 5917–5924, 2013. [3] X. Zhao et al., Optics Express, vol. 21, 25, 31660–31667, 2013. [4] V. Sivakumar et.al., Journal of the Electrochemical Society, vol. 152, 10, H168–H171, 2005 [5] F. Gu et al., Journal of Crystal Growth, vol. 289, 1, 400–404, 2006.

Resume : Perovskites-containing Eu3+ ions are promising for optoelectronic devices, LEDs, and lasers due to their excellent photoluminescence properties. The human eye sees optical radiation in the europium emission as red light, making these materials particularly important. Properties of SrTiO3 depend not only on the chemical composition but also on the structure and morphology. A decrease in the grain size of SrTiO3 at the nanoscale leads to distinctive properties compared to the bulk material. Different formulae describe europium-doped strontium titanate nanopowders: (i) Sr1-3x/2EuxTiO3 and (ii) Sr1-xEuxTi1-x/4O3, where 0  x  0.07, were prepared by the alkoxide variant of the sol-gel method. After annealing at 1000oC for 3 hours, the non-stoichiometric powders with built-in Ti vacancies (Sr1-xEuxTi1-x/4O3) show single-phase compositions for all the samples stoichiometric powders described by the formula Sr1-3x/2EuxTiO3 show small amounts of secondary phases (TiO2 and Sr3Ti2O7). A slight decrease in the average particle size and a higher aggregation tendency were observed with the increase of the dopant concentration. SEM investigations of the ceramics sintered at 1400oC for 4 hours indicate significant changes in the microstructural features due to dopant content and stoichiometry. A noticeable decrease in the average grain size was observed as the Eu3+ content increased, irrespective of the presence or absence of Ti vacancies in the nominal formula. On the other hand, more homogeneous and denser microstructures were observed for the ceramics with built-in titanium vacancies than in the case of the ceramics with strontium compensating defects, no matter the Eu3+ concentration. The luminescence properties of the perovskites are improved by increasing the europium concentration. This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS – UEFISCDI, project number PN-III-P1-1.1-TE-2021-1624 within PNCDI III and project 16N/08.02.2019 Program NUCLEU-LAPLAS VI.

Resume : The fabrication of nanomaterial semiconductors using metal oxide crystals is being widely pursued. In recent research, high-power solar cells based on laminated structures of Cu2O and ZnO crystals have been widely investigated. These metal oxides are crystallized using a hydrothermal reaction or a high-frequency plasma method. The sol-gel method is widely applied to form metal oxide ceramics. Studies have also explored the sintering of a fine powder of metal oxides. The amorphous metal oxide formed by sintering can be applied to gas sensors and as adsorbents. This research proposes a method for forming sintered Cu2O structures. In our previous work, we successfully formed high-purity Cu dendrite crystals and pulverized these crystals into fine powders. This method of forming sintered Cu2O structures differs from conventional methods in terms of the starting point, which uses a fine powder of Cu dendrite crystals. Cu dendrite crystals were pulverized into high-purity Cu nanoparticles using microbubbles produced by an ultrasonic homogenizer. Thus, a powder was prepared by mixing the formed nanoparticles with microsized Cu dendrite crystals. This powder was sintered in an oxidizing furnace (oxygen atmosphere: 20 vol.%). at a furnace temperature of 500 ℃, and a sintered Cu2O structure was successfully formed. This structure was amorphous and had no crystalline structure. A porous structure with numerous microsized voids derived from the Cu dendrite structure was formed. It was found that sintering with Cu nanoparticles between the Cu dendrite structures contributed to the shape stabilization of the sintered Cu2O structure as an adhesive. The thus-formed porous Cu2O structure could change the oxidation rate by subsequent reduction treatment. In addition, it had a high adsorption capacity owing to its porous structure. Moreover, its high adsorption affinity toward Cl was experimentally confirmed, rendering it promising for use as a Cl gas adsorbent.

Resume : Carbon nanowalls (CNWs) have outstanding strength, can be highly electrically conducting or semiconducting, have a large specific surface area per unit mass. The electrical characteristic of CNWs is changed by parameter such as surface number density, height and thickness of it. Those have great effect on CNWs and can be adjusted as growth interlayer. In this study, The CNWs were grown on molybdenum disulfide (MoS2) interlayer analyze the structural characteristics. The MoS2 interlayer were synthesized on Si substrate using a RF-magnetron sputtering. And CNWs were grown on interlayer using a microwave plasma enhanced chemical vapor deposition (MPECVD) system with a mixture of methane (CH4) and hydrogen (H2) gases. The CNWs grown on MoS2 layers were characterized by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). Structural defect analysis of CNWs was performed using Raman spectroscopy. The unique growth properties of CNWs have open the doors to performance enhancement in a wide range of electrodes and devices. Acknowledgement: This work was supported by the Korea Institute of Energy Technology Evaluation and Planning(KETEP) and the Ministry of Trade, Industry & Energy(MOTIE) of the Republic of Korea (No. 20204030200080). and This work was supported by the National Research Foundation of Korea(NRF) grant funded by the Korea government. (MSIT) (2022R1A2C1009709)

Resume : Optical sensors based on refractive index change due to changes in surrounding medium are an active research area, because they can be useful in many fields, including biomedicine. Metal nanoparticles exhibit a phenomenon called localised surface plasmon resonance (LSPR), manifested by peaks in optical spectra. One of the possible configurations for such sensor is porous anodized aluminium oxide (PAAO) covered with gold nanoparticles (Au NPs). In this work, we systematically investigated various aspects of this hybrid material using finite-difference time-domain (FDTD) modelling. For modelling, we used Ansys-Lumerical software (version 2021 R2.3). The model consisted of 3 layers: 1) aluminium (Palik) substrate, 2) varying thickness aluminium oxide (Palik) layer with cylindrical pores of 35 nm diameter and 100 nm distance between the pore centres, and 3) 60 nm diameter Au (Johnson and Christy) NPs directly above each pore. The simulation region started 300 nm below the substrate/PAAO interface and ended 1300 nm above the PAAO surface, while the x- and y-spans were equal to one period of the structure. The mesh override region was from 50 nm below the PAAO to 50 nm above the nanoparticles with a step size in each direction of 2 nm. The broadband fixed angle source technique (BFAST) plane wave light source was placed 500 nm above PAAO at an angle with a wavelength range of 300 nm – 1000 nm. The frequency domain field and power monitor was placed 1000 nm above PAAO to register scattered light. Both s- and p-polarized light was modelled. At 260 nm PAAO thickness, a peak emerged at 600 nm, which can be attributed to Au NPs LSPR, which red-shifted with increased PAAO thickness. The simulations show that for 290 nm PAAO thickness LSPR peaks are best observable at 45 deg. – 65 deg. angle of incidence. This peak also red-shifts with an increase in the refractive index of the surrounding medium. The sensitivity was calculated to be 235 nm/RIU. While designing a refractive index sensor, the thickness of the PAAO, the incidence angle of the light as well as geometrical parameters must be considered. This research is supported by the European Regional Development Fund postdoctoral project "Patterned hybrid multilayer films for optical sensors", No. 1.1.1.2/VIAA/4/20/615. Results data sets are available on Zenodo Community dedicated to the postdoctoral project: https://zenodo.org/communities/postdoc-latvia-615.

Resume : The syntheses of modern nanostructured materials for electronic and photonic devices and sensors often require plasma treatment of interfaces to modify or enhance their properties. Radio-frequency (RF) plasmas, that are widely used for film synthesis or treatment, can be used as a versatile source of ions with energies that can be tuned exactly to reach the activation energy of desired processes (e.g. doping or creating active sites on the surface) and keep the material otherwise unharmed. We use the combination of a capacitively coupled RF plasma with an inductively coupled plasma to tune the energy of nitrogen ions in the range of units to tens of electronvolts to modify the hydrothermaly grown films with NiCo2O4 nanowires used as electrodes for Zn-air batteries. Nitrogen doping is being considered to improve the electric conductivity of metal oxide nanostructures which leads to better electrocatalytic activity. Unlike the wet chemical treatment with nitrogen-containing precursors, the plasma treatment does not require high temperature annealing and avoids chemical contamination. We study the effect of nitrogen plasma treatment on the cycling performance of a Zn-air battery with a NiCo2O4 electrode using cyclic voltammetry, oxygen evolution reaction (OER) and oxygen reduction reaction (ORR). The electrodes after nitrogen plasma treatment show higher OER and ORR performance, faster reaction rate constant and higher double-layer capacitance indicating the increase of the active surface area.

Resume : With the advent of new technological advances in materials science and engineering, much current attention has been focused on the development of electronic equipment employing the use of electromagnetic interference (EMI) shielding materials. In this study, we present an innovative approach for the fabricating efficient electromagnetic shielding material by tuning the microstructure of the filler in a flexible PDMS polymer matrix. Hollow prussian blue anchored reduced graphene oxide (HPBR) plays an active role as a filler in which the magnetic property of Prussian blue has been changed from solid to hollow. As PDMS-based composite with solid or hollow Prussian blue showed lower EMI SET values of ∼6.31 and ∼7.51 dB respectively at 14.5 GHz, which was further improved after addition of rGO. However, the dielectric and magnetic properties can be altered by changing the mass ratio of the precursors, K3Fe(CN)6 and GO with a 1:1 mass ratio (HPBR1-1), the polymer composite containing filler HPBR1-1 exhibited EMI SET value of ∼32.01 along with the highest absorption property EMI SEA value of ∼27.07 dB (SEA% ∼84.56) in comparison to other composites with a thickness of ∼2.4 mm. Such excellent EM attenuation properties can be attributed to the synergistic effect between magnetic and dielectric loss, polarization relaxation, conductive network, magnetic property, and multiple reflections, which claim an innovative design for advanced and effective EM wave absorbers having strong absorption capacity.

Resume : In the last decade perovskites became one of the most investigated compounds. Their high photoluminescence and quantum yield, large optical gain and narrow emission line make them promising candidates not only for the solar cells, but also for light emitting diodes, photodetectors and lasers. The solution-processed perovskites in the form of the thin films are easily obtainable, scalable and can be successfully employed in the all abovementioned applications. All-inorganic perovskites, e.g. CsPbBr3, are possessing increased stability and outstanding electronic properties, comparing to the organic-inorganic hybrid perovskites; however, both the morphological and structural properties of the films, as well as resulting optical and electrical performance still can be improved. Nowadays the B-site doping is a promising choice for tuning the photoluminescence signal (e.g. changing of an emission peak) from perovskites, as well as for an increment of their chemical stability. Here we report results on properties of the Ce-doped CsPbBr3 thin films, obtained by a conventional 1-step spin-coating process. The doped films show a strong increase in the photoluminescent intensity, which correlates with a concentration of the dopant. The films were characterized by means of steady-state photoluminescent and Raman-scattering spectroscopy, as well as by X-ray diffraction analysis and scanning electron microscopy. We found that Ce doping practically does not impact on photoluminescence and absorption peak positions, but increases photoluminescence intensity. This can open new possibilities for optoelectronic applications of perovskites, as well as to shed the light on the interaction of the host perovskite material with the impurities ions.

Resume : Nanoscale materials represent a cutting-edge technology used in current scientific research and industrial development. Overall, the glamor of nanostructured materials is a significant alteration of their properties, due to the confinement of their dimensions and influence of surface effects. Therefore, several materials, like silicon in form of nanocrystals (SiNCs) (representing an environmental and health-friendly material), can report a relatively high light emission efficiency with good spectral tunability in visible and near-infrared spectral regions. However, a broader application of the SiNCs is limited by complex surface modification processes and poor solubility in liquids (e.g., water). In our work, we have recently shown, that the non-thermal plasma (NTP) can be used for effective surface modification of SiNCs in liquid media, by discharge generation of plasma-activated liquids (PAL). The technique is based on gentle treatment of the liquid by the plasma discharge, where reactive species could be formed and provide the surface chemical reactions of dispersed SiNCs. The plasma-activated water (PAW) was effectively used for surface passivation on electrochemically prepared SiNCs. However, the challenging factor of the PAL based surface modification is tuning of the PAL chemical composition. For example, in case of PAW, significant amount of reactive oxygen species (e.g., hydrogen peroxide) can lead to damage of the SiNCs, blocking further surface reactions and vanquishing the SiNCs property such as photoluminescence (PL). Recently, we have proven that using specific discharge and surrounding conditions a unique PAW composition is achieved without hydrogen peroxide and with a very high concentration of nitrogen species (HiN:PAW). The treatment of SiNCs with HiN:PAW leads to nitrogen-based surface modification, demonstrated by the distinctive increase in quantum yield (more than 10 times). Additionally, the modification is stable for more than a month and provides better water solubility, which makes the treated SiNCs more interesting in further application in technologies using water as a solvent (e.g., preparation of electrodes for lithium-based batteries). Moreover, we have showed that the NTP technique can be successfully used for the activation of organic solvents (e.g. acetic acid). The resulting carbon-based termination of SiNCs in such PAL led to better dispersibility, accompanied by enhancement of the intensity of PL and its overall tunability. In combination of variety of the organic liquids, the PAL treatment is suitable for broad range of applications. However, for efficient modification the discharge condition needed to be properly changed, mainly using a closed chamber reactor space filled with inert gas (e.g., Argon) to suppress the flammability of the organic liquid. Moreover, the re-design of the electrodes needed to be done for less conductive liquids, where instead of transient spark, the gentler jet plasma is utilized.

Resume : Introduction Smart implants provide therapeutic, monitoring, and diagnostic capabilities; and they have been reported to be used for knee arthroplasty treatments [1]. To date, smart implants have been able to measure physical parameters from inside the body [2]. However, there are still technical challenges to integrating smart implants into daily healthcare practice [3], such as suboptimal implant mechanical performance, biocompatibility of sensor material and circuitry having to be protected from bodily fluids. Therefore, next-generation smart implants need to be small, robust, inexpensive and necessitate little variation in existing implant design. Methods A series of strain gauges were designed to be embedded within an orthopaedic implant. Three sets of serpentine structured strain gauges were analysed: a conventional foil strain gauge with a polyimide backing, a high-resolution silver nanoparticle ink direct-write printed strain gauge with polyimide backing and a tripropylene glycol diacrylate backing. Strain gauge printing parameters were optimised to obtain desired resolution and repeatability of print quality. The mechanical properties of the strain gauges were tested with a three-point flexural test which simulated dynamic offloading mechanism of a knee joint. Results and Discussion Optimal values were obtained for the power, heat, time, delay, and velocity parameters in high resolution ( ≤10 µm) printing. Repeatability was achieved for sensor manufacturing utilising the optimal parameters. Biocompatibility analysis showed that conventional polyimide and tripropylene glycol diacrylate backing were both biocompatible and had the potential to be used as a dielectric sensor layer. Furthermore, stress-strain characteristic curves were obtained and analysed for the different gauges using an Arduino microcontroller. Results showed that tripropylene glycol diacrylate backing that was deposited on implant structure without bonding adhesive performed similarly to a conventional foil gauge for forces up to 1.5 KN. Conclusion In summary, this research provides a potential solution for strain detection for prosthesis implants to detect offloading and implant failure using a novel hybrid multilayer manufacturing technique. Exploring different dielectric layers and bonding techniques for strain gauges allows the sensors to be embedded directly within the implant structure. Acknowledgements We acknowledge financial support from EPSRC MAPP Future Manufacturing Hub (EP/P006566/1, www.mapp.ac.uk) and The Royal Academy of Engineering (CiET1819/10). We acknowledge The Oxford Polymer Group and the Nanoengineered Systems Laboratory. Also, thanks to all PhD students & PDRAs the Materials, Structures and Manufacturing Group members. References [1] Riddle DL, Jiranek WA, and Hayes CW, Arthritis Rheumatol., 2014,8: 2134–2143. [2] O’Connor C and Kiourti A, J. Bio- Tribo-Corrosion,2017, 2:20. [3] Ledet EH et al., Innov. Entrep. Heal,2018.,5:41–5

Resume : The rapid growth of portable, flexible and wearable small devices and integrated electronics has increased the need for on-chip and small-scale energy storage devices such as micro-supercapacitors. While small batteries still face numerous limitations due to low power transmission, short lifespan, low charge-discharge rate, and complex architecture, the aforementioned challenges put micro-supercapacitors to the fore. In that manner, developing new strategies for the large-scale fabrication of supercapacitor devices is a must to meet the demands of the industry. Micro-supercapacitors can be integrated into series or parallel with miniature electronic devices and provide long life and fast charge/discharge rate. Micro-supercapacitors can provide higher power density in a small volume. This allows them to be suitable for flexible integrated systems that require high power density. Moreover, by using the interconnected coplanar electrode architecture, rate capacity and power density can be further increased as the structure provides a high active surface area. Molybdenum disulfide (MoS2) attracted lots of interest with successful demonstrations in applications such as electrocatalysts, transistors, and especially energy storage devices. 1T- MoS2 is metallic and has favorable electrochemical properties owing to the layers' ability to expand and intercalate ions with high electrical conductivity. In this work, the ultrasonic spray coating method is used for the deposition of 1T- MoS2 thin films on desired substrates. Firstly, a result of 264 F/g specific capacitance was obtained through cyclic voltammetry with a 5 mV/s scan rate in a three-electrode setup with a KOH electrolyte. Then, a simple laser ablation method is utilized to fabricate interdigitated finger electrodes to obtain 1T-MoS2 micro-supercapacitors. The capacitive behavior of 1T- MoS2 was investigated through cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy. Detailed analysis of the capacitive behavior will be presented with the comparison of patterning and amount/thickness of the active material. With the integration of micro-supercapacitors, many forward-looking flexible, wearable and portable devices in various applications can be developed. This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No:220M003.

Resume : One of the most common elements on our planet is silicon (Si). This versatile semiconductor founds, due to its properties, wide range of applications from ceramics to IT technologies. However, even further utilization of this element is limited by complicated modification of its properties, such as low light emission efficiency etc. One of the possible ways how to overcome this disadvantage is usage of Si's nanostructure forms (SiNFs). Thanks to a quantum effects (quantum confinement effect etc.) and an influence of high surface to volume ratio. In contrast to the bulk Si its nanoforms show a lot of interesting properties like an efficient light emission, high surface reactivity and mechanical resistance. The challenging factor of SiNFs application is its difficult synthetize. To prepare high quality of SiNFs with high material yield is almost impossible. One of the current most perspective ways of their synthesis is using non-thermal plasma, which are based on dissociation and subsequent crystallization of Si nanoparticles (SiNPs) from precursor gas such as silane (SiH4) using non-thermal plasma. These SiNPs show very good crystallinity and surface properties, which can be easily modified by changes of synthesis conditions such as plasma power, composition of used gases etc. In contrast to other synthesis methods, SiNPs created using non-thermal plasma system at specific conditions, can carry high amount of hydrogen. Such nanocrystals can be easily ignited, with great energy release. For this reason, SiNPs can possibly become a perspective medium in the explosives or because of high hydrogen capacity can be applied in current energetics. In this work we present our results based on synthesis optimization of SiNPs with high hydrogen concentration and characterization of its flammability using high temperature and also laser beam. Our measurements showed that the silicon flammability is directly related to their crystallinity and size. Smaller and amorphous nanocrystals where the most sensitive to ignition (higher effective surface). In some cases, they even show self-igniting when they get into contact with air. Fourier-transform infrared (FTIR) spectroscopy measurements showed that the more sensitive nanocrystals possess higher concentration of Si-H bonds in contrast to the other Si-Hx bonds ones. Our preliminary measurements of released energy from SiNPs showed that the released energy of these nanocrystals can reach value almost 7000 calories per gram.

Resume : The importance of ensuring device continuity and safety has grown as the number of electronic devices in daily life has increased dramatically. The key aspects in the production of the described conditions are the heat released by the devices and the management of this heat. This issue has highlighted the significance and demand for items that can be manufactured in three-dimensional complex structures using thermally conductive and electrically insulating materials. Additive manufacturing is a fast and cost-effective approach for the prototype production. Complex shapes can be produced and the product can be optimized for maximum efficiency using different print settings. Polylactic acid (PLA) is the most widely used polymer for additive manufacturing because of its easily formable and recyclable structure. In the scope of this study, our aim is to prepare a 3D printable filament that shows thermally conductive and electrically insulative features by the addition of h-BN to the PLA matrix. For this purpose, a filament winder is designed in order to produce a filament with a diameter of 1.75 mm. Simultaneously, h-BN additives are exfoliated with the shear exfoliation method. The recycling process increased the fabrication yield, where mono or few-layer h-BN is obtained as revealed by further characterizations. Exfoliated h-BN shows a better thermal diffusion rate in the composite structure compared to the pristine powder. This is because phonon scattering is prevented by decreasing the number of layers. Detailed characterizations and 3D-printed electronic devices that demonstrate the thermal effect of h-BN will be provided.

Resume : The complementary resistive switching of Ag5Te3 nanoparticle-based resistive random access memory (RRAM) is reported for the first time in this study. The Ag/ Ag5Te3/Au structure on the glass substrate was used to fabricate solution-processed RRAM devices. The colloidal method was used to create Ag5Te3 nanoparticles. To form a thin film, the purified Ag5Te3 nanoparticles were spin-coated with an aqueous solution. The spin-coated Ag5Te3 thin films were annealed at different temperatures, and changes in the physical and chemical properties and RRAM properties of the thin films were observed. Although the high-resistance state (HRS) / low-resistance state (LRS) ratio was approximately 10, the fabricated device demonstrated complementary resistive switching characteristics regardless of temperature. Furthermore, we observed a temperature-related change in set/reset voltage.

Resume : To improve bias stability, we investigated the effect of an ultra-thin particulate aluminum layer deposited on sol-gel processed SnO₂ thin-film transistors (TFTs). Metal Oxide TFTs are widely used due to their high electron mobility, ease of fabrication, and transparency. Metal Oxide TFTs, on the other hand, are electrically unstable due to oxygen vacancies and defects. To solve this problem, we formed an ultra-thin particulate aluminum layer on SnO₂ TFT. In this experiment, after preparing SnO₂ TFT by sol-gel process, Al was deposited on the SnO₂ layer by thermal evaporation. In addition, an annealing process at 300°C for 20 minutes was followed. Under the negative bias stability test, SnO₂ TFT indicates a mobility decrease from 2.19cm²/Vs to 1.27cm²/Vs and a -5.21V threshold voltage shift. The device with an Al layer, on the other hand, has a mobility change from 1.09cm²/Vs to 1.26cm²/Vs and a -2.22V threshold voltage shift. These results show that the Al layer successfully improved the negative bias stability. We believe that sol-gel processed SnO₂ TFTs with ultra-thin particulate aluminum layers are a promising candidate for high stability applications in transparent electronics.

Resume : We investigated the passivation effect of Au in an Ag/Y2O3/ITO RRAM device in this work. Ag is commonly used as the top electrode in RRAM devices, as an active material. However, it can be oxidized easily. To address this issue, we deposited Au as a passivation layer on an Ag-top electrode and monitored the change in memory characteristics over time. In this experiment, 100 nm of Au was deposited on 20 nm of Ag-top electrode using a thermal evaporator. A device with an Au layer had consistent HRS and LRS resistance up to 30 days after deposition, whereas a device without an Au layer had high LRS resistance on the 30th day, which was similar to the HRS resistance. On the 30th day, the device without the Au layer had poorer endurance characteristics than the device with the Au layer, and the tendency in retention time characteristics was the same. These findings confirm that the deposited Au layer successfully prevented the Ag layer from oxidizing. We anticipate that RRAM with active material as the top electrode will continue to function reliably as a memory device over time with additional deposition of the Au passivation layer.

Resume : Cathodic electrodeposition of zinc oxide (ZnO) thin films employing oxygen reduction reaction (ORR) has been widely studied. The process directly yields highly crystallized thin films at low temperatures. We have also achieved hybrid thin films with organic dye molecules that act as structure directing agents (SDAs) to strongly modify the crystal growth [2]. Highly porous sponge-like crystals were obtained in the presence of eosinY (EY), which exhibited a high performance as a photoelectrode for dye-sensitized solar cells (DSSCs). The added EY was found to catalyze ORR to promote formation of ZnO, rather than hindering it.　Furthermore, the redox state of eosin Y changed the ORR catalytic mechanism and significantly affected the deposited film morphology. It is important to give a full understanding how the ORR is influenced in the presence of Zinc ion and also by the presence of catalytic molecules such as EY. We have carried out hydrodynamic electroanalysis employing rotating ring-disk electrode (RRDE) that allows monitoring of formation of hydrogen peroxide. On the gold disk electrode surface, a diffusion-limited current for the four-electron reduction of oxygen was observed. The addition of zinc chloride resulted in the electrodeposition of ZnO on the electrode surface and a decrease in the current value indicating a decrease in the ORR kinetics. Even though the disk current decreased, the ring current increased, indicating that two-electron reduction accompanied by the formation of hydrogen peroxide occurs on the ZnO surface. When EY was added to the zinc oxide deposition bath, the disk current increased due to its catalytic activity. On the other hand, the catalytic mechanism changed depending on the reduction of EY by the applied potential. At the EY non-reducing condition, the hydrogen peroxide formation increased as the ORR kinetics increased. Therefore, the deposited EY acted as a catalyst to promote two-electron reduction. Conversely, at the EY reducing potential condition, hydrogen peroxide formation decreased despite an increase in oxygen reduction current. The results suggest redox mediation from reduced EY to hydrogen peroxide, which was converted to a four-electron reduction of oxygen. Based on the EY catalytic mechanism at each potential condition, rate factors will be determined, and the inorganic-organic hybrid film deposition mechanism will be discussed.

Resume : Cathodic electrodeposition of ZnO has been studied because it is possible to obtain highly crystalline ZnO thin films in a solution process and to apply them to sensors, catalysts, and solar cells. It is important to control the morphology of ZnO thin films because the morphology of ZnO thin films affects the performance of those devices. We have studied that the oxygen reduction activity of F-doped SnO2 (FTO) substrates changes the morphology of ZnO thin films. This suggests that the substrate may control the morphology of the ZnO thin film. Factors related to the substrate include oxygen reduction activity, roughness, and crystal growth method. We investigated the effects of these factors with ZnO thin films using substrates of FTO, Indium Tin Oxide (ITO), Al-doped ZnO (AZO), and Glassy carbon (GC). ZnO was carried out by potentiostatic electrolysis at an FTO, ITO, AZO, GC rotating disk electrode (RDE, ω = 500 rpm) at -1.0 V (vs. Ag/AgCl) in an O2-saturated aqueous electrolyte (70ºC) containing 5 mM ZnCl2 for 10 min. The ZnO films on FTO and ITO had X-ray diffraction peaks of 100, 002, and 101, while the ZnO thin films on AZO and GC had only the 002 peak. This is also reflected in the surface morphology in SEM: FTO and ITO were randomly arranged, confirming multiple planes of zinc oxide hexagonal columns. On the other hand, GC and AZO were finely and orderly aligned, confirming the hexagonal faces of the c-axis. The crystal size increased in the order of AZO, GC, FTO, ITO. This change depends on the behavior during nucleation because the behavior of the chronoamperogram in the early stage of electrodeposition is different. The variation of thin film morphology with electrodeposition time revealed the following: 1) AZO was highly oriented along the c-axis, reflecting the 002 plane orientation of the substrate due to epitaxial growth; 2) FTO and ITO nucleated and grew horizontally until the crystals contact each other, resulting in a random arrangement; 3) the nucleation of GC was not very dense, but the flat substrate probably promoted vertical growth. FTO, AZO, and GC had similar oxygen reduction activities(×10 -6 – 10-7 cm s-1). Whereas, ITO had lower oxygen reduction activities(×10 -10 cm s-1). The higher the oxygen reduction activity, the smaller the particles and the denser the nucleation tends to occur. In addition, the roughness of the substrate is larger for AZO, GC, ITO, and FTO, and the order of roughness of the thin films is different. This is because it is affected more by oxygen reduction activity than roughness.

Resume : With the development of miniaturized electronics, there is a need to develop small energy storage devices to meet the energy needs of these devices. Supercapacitors can meet this need with their fast charge-discharge cycles and long lifetimes. While material research for supercapacitors are important to meet the energy requirements, development of device fabrication route is also a must to allow mass production of such devices. In this regard, it is essential to produce flexible supercapacitors that can be mass-produced, especially in wearable technologies and small-sized electronic devices. Microsupercapacitor production with the direct ink writing (DIW) holds great potential in that respect, as the prepared ink-type electrode materials can be applied to the desired substrates, allow the production of electrodes in the desired shape and size. In the proposed project, our aim is to prepare DIW inks with silver nanowires (Ag NWs) and 1T phase molybdenum disulfide (1T-MoS2) nanosheets. Microsupercapacitors are then printed onto flexible substrates by DIW method. A commercial 3D printer is modified and turned into a DIW system for this purpose. The Ag NW / 1T-MoS2 materials produced were combined and turned into a dense ink with the additive of a cellulose-based condenser. A specific capacitance of 0.86 mF.cm-1 was obtained. Detailed fabrication parameters and electrochemical characterization will be provided. This work was supported by The Scientific and Technological Research Council of Turkey (TUBITAK) under Grant No: 120M374. *Mete Batuhan Durukan and Mustafa Caner Gorur have contributed this work equally.

Resume : Interest in real-time healthcare monitoring, tactile systems and electronic sensing for robotics is increased in recent years, which brought forth the development of state-of-art miniaturized systems for wearable electronics. Resistive, piezoelectric and capacitive type of such sensors are developed in this manner to fill the need for wearable sensing systems. Among them, capacitive sensors offer advantages such as simple device structure, temperature independency, low pressure detection and fast dynamic response. Research on electrode materials to modulate the sensitivity of capacitive sensors still remains inconclusive. Most research on capacitive sensors involves the fabrication of newly developed polymer-based dielectrics or modification of the dielectric layers by adding microstructured surfaces. Herein, we propose the use ultrasonic spray deposited nickel oxide (NiO) structures on fluorine doped tin oxide (FTO) substrates to control the sensitivity of the capacitive sensors. By controlling the amplitude of AC signal, faradaic reactions on NiO surfaces can be triggered, resulting in an increase in the capacitance of the system especially under pressure. When used with appropriate solid-state electrolyte as the dielectric layer, NiO structures offered higher capacitance and higher sensitivity than bare FTO surfaces. Thorough analysis including electrochemical characterization, impedance spectroscopy and sensitivity measurements with an LCR meter will be presented in conjunction with different device structures. *Mete Batuhan Durukan and Melih Ogeday Cicek have contributed this work equally.

Resume : Terahertz (THz) spectroscopy is a state-of-the-art implementation for analysing various biological materials, as well as nanoparticles. Using metamaterials in conjugation with THz spectroscopy is an important technique towards bridging the THz-gap by providing a large response to THz radiation of the inspected material and nano-particles that are in a low concentration, where most natural materials exhibit only weak responses to its electric and magnetic fields. With recent advances in THz spectroscopy, engineered metamaterial nanostructures are used to detect and determine dielectric properties of viruses, bacteria, and fungi, using the concept of inductor-capacitor (LC) resonance-based particle detection. The nanostructure is designed as an LC element, with fundamental resonant frequency, F0=1⁄(2π√LC). Here the factor L is decided by the geometric parameters of the fabricated nanostructure, and C is highly dependent on the capacitive gap (W) and effective dielectric constant (εeff) of the LC resonant nanostructure. A change in F0 of can be brought by any foreign substance deposited in the capacitive gap; changing the εeff and the capacitance, resulting in redshift of F0 (ΔF) with respect to the pristine LC circuit in the array. For the detection of nanoparticles/biomolecules using metamaterial-based structures, we physically redesign the LC resonant geometry with the intention of maximizing the cap-gap-area. The cap-gap width is reduced in order to obtain the plasmonic enhancement that is associated with the nanometric scale of such a capacitor gap. Placing the capacitor gaps at both geometric diagonals of a square inductor enables the exhaled viruses and particles to be detected in both S and P polarization states (when using a single polarization spectrometer) with a rectangular all-around singular inductor structure, for its resonance detection. This improvement enables low concentration particle detection by increasing the capacitive gap lengths compared to a basic split ring resonator. This effectively increases the sensitivity by 5-folds, by increasing the probability of biomolecules/particles falling inside the capacitive gap and yet maintaining a sub-micron capacitor gap, thereby enabling more pronounced resonance frequency shifts for breath samples even with a lower virus load. Our results are supported with system-level CST simulations and THz impedance spectroscopy with nanoparticles, Bovine Serum Albumin (BSA) solutions, and viruses. To realize a kit for biosensing, we have also designed a plastic enclosure (radome) for the metamaterial chip, which serves as a protective enclosure and an anti-reflective coating for the chip, thereby improving the THz transmission, by impedance matching techniques. Since our initial results have shown nearly 90% accuracy to detect coronaviruses in breath-test, we further aim to detect various viruses/bacteria from breath/swab of individuals with higher accuracy, with our designed kit.

Resume : The metallic nanoparticles are of great interest in different fields due to their unique properties, finding applications in chemical imaging, solar cells, biomaterials, adsorption of organic molecules, surface-enhanced Raman scattering, sensors, and biosensors. The research performed in this work is related to comparing the plasmonic properties of Au nanoparticles deposited on different substrates. Firstly, the nanoparticles are deposited on pristine crystal (001) SiO2 and glass substrates. Secondly, the nanoparticles are grown on thin films of semiconductors oxides (WO3, TiO2, and ITO) with different crystal phases and roughness. A pulsed laser deposition technique is applied using a nanosecond laser system. The size, shapes, and distribution of Au nanoparticles in dependence on the substrates surface structure, temperature, crystallinity, and a number of laser pulses are investigated. The energy dispersive X-ray analyses and elemental maps confirmed the presence of Au-NPs and the atomic nature and compositions of the thin films. The particle sizes are determined to be in tens (21- 43) of manometers range. The morphology is determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The influence of the AU nanoparticle's morphology on their optical properties is investigated by UV-VIS spectroscopy. The surface plasmon resonance of the Au nanoparticles deposited on the thin films - polycrystalline (ITO, TiO2, and WO3) and amorphous TiO2 - is red-shifted over 700 nm. Thus, being larger than Au-NPs deposited on the pristine substrates as glass (Si and SiO2). Increasing the substrate temperature, the surface plasmon resonance picks of Au-nanoparticles are blue-shifted due to the density improvement and size reduction as confirmed by SEM and AFM. The AFM complementary investigations support the SEM and UV-VIS-NIR results and surface plasmon resonance effect behavior, morphology, and size range of the Au nanoparticles.

Resume : Black titania nanomaterials are of great scientific interest due to their excellent photocatalytic properties compared with conventional white titania. Colored samples are superior to white titania in photocatalytic and optical adsorption properties. In addition to improved photocatalysis and light absorption performance, black titania nanomaterials have proven promising in other environmental applications. Most studies of black titania are devoted to the polycrystalline nanomaterials, and only a few consider black titania nanotubes. C-doping can change the structure and photocatalytic activity of titania. In addition to carbon, other electrolyte components, such as F, N, P, and S, can also affect the morphology and composition of titania nanotubes. Our work studies the structural peculiarities of titania nanotubes obtained by two-step anodizing in an ethylene glycol electrolyte containing NH4F and H2O. The anodizing procedure consisted of a potential ramp from 0 to 40 V followed by double-sided constant voltage anodizing for 1 h. Crystalline titania nanotubes were obtained by annealing at 450 °C in the air or 500 °С in Н2. According to SEM, TiO2 nanotubes possess a highly-ordered nanotubed structure with a pore diameter of 60 nm, a wall thickness of 12 nm, and a length of 13 μm. The intense black color of TiO2 nanotubes was obtained after heating in hydrogen at 500 °C. XPS studies showed that the carbon content on the surface of the black TiO2 nanotubes is 21.5±1 at.%, of which 15 at.% is graphite carbon. It has been concluded that carbon contributes to the black color of titania nanotubes. Raman, IR, and XPS data show that the black color is caused by the presence of amorphous graphite-like carbon (graphitized carbon). The sp2-C content significantly exceeds the content of Ti3+ ions. EPR studies also showed that the observed signal with ∆В = 0.4–1.1 mТ, and g = 2.0018±0.0002 can be attributed to aryl-type radicals, i.e., polycondensed graphite-like molecules. There is an oriented arrangement of carbon rings along the walls of the black titania nanotubes, which is similar to the formation of carbon nanotubes inside the pores. The formation of graphitized carbon in a regular TiO2 nanoporous structure promotes the formation of intensely colored films. The presence of carbon and the lack of oxygen are necessary conditions for the growth of oxide crystals oriented along a given direction (in the form of whiskers) during metal oxidation. The modification of metal oxide films by products of the electrochemical transformation of electrolyte components provides new opportunities for changing the properties of materials. The carbon inclusions in the nanostructured porous structure of titania nanotubes give a rich black color, essential for obtaining light-absorbing coatings with a minimal reflection effect. Controlling the carbon formation processes can make it possible to adjust the optical and other properties of titania nanotubes films.

Resume : Recently, ZnO material has been widely used in optoelectronics and thin-film solar cell devices. This is mainly due to its advantages of non-toxicity, low cost and relatively higher conductivity properties compared to other metal oxide materials such as SnO2. However, ZnO typically exhibits low conductivity compared to In2O3 and ITO-based thin films. Therefore, the main objective of this study is to experimentally investigate the impact of the RF sputtering power on the Al-doped ZnO thin films electrical properties. Al-doped ZnO layers were deposited on glass substrate using RF magnetron sputtering technique at different sputter power values ranging from 60 W to 140 W. It was revealed that the sputtering power could modulate the electrical characteristics of Al-ZnO material, tuning favorable conductivity and electron mobility at an appropriate sputter power. Therefore, the present study can open a new pathway for the design and fabrication of optoelectronic and photovoltaic devices.

Resume : For a long time, various kinds of inorganic nanoparticles, including carbon nanostructures, were considered as possible carriers for the creation of drug delivery systems. Many years of experience with such nanoparticles showed positive results. Several mechanisms have been proposed for the stimulated release of drugs from complexes. Usually, inorganic nanoparticles were used as a nucleus, which was then coated with polymers and functionalized to prevent direct interaction with the cell due to the toxicity of foresaid structures. But even if some of these complexes was working at the level of cell cultures, when moved to the organism most of them lost their efficiency. The boron nitride (BN) nanoflakes application for biological purpose, namely for fluorescence, Raman spectroscopy and coherent-anti Stocks Raman mapping of BN and doxorubicin (DOX), are reported. We found that the absorption spectra of DOX composites with various concentrations of BN nanoflakes solutions in water is sum of pure DOX and scattered like BN nanoflakes dispersion spectra. It should also be mentioned that the aqueous dispersion of BN nanoflakes (0.2 mg/ml) with milky color is stable for more than 24 months. DOX molecules perfectly adsorbed on BN manoflakes. The adsorption capacity of BN nanoflakes after 2h after solution preparation was 75 mg/g. After 24h it’s increases to 110 mg/ml.

Resume : Charge-transfer (CT) complexes exhibit optical properties that cannot be achieved with a single molecule due to the new electronic state between two molecules and are expected to be used as luminescent and photovoltaic materials. In our previous study, combination of Methylene blue (MB) and Eosin Y (EY) has observed as a charge-transfer (CT) complex pair. However, to apply those CT complexes as optical devices, a combination of carrier transport layers was necessary. On the other hand, We have achieved organic dye/CuSCN or ZnO hybrid thin films by addition of organic dyes into the electrolytic bath for cathodic electrodeposition [1,2]. In this study, electrodeposition of inorganic semiconductor/MB-EY hybrid thin films was performed using a group of dyes that selectively selective hybridizing with n-ZnO and p-CuSCN, which are responsible for electron and hole transport, and the chemical interactions between these dye molecules and the deposition mechanism were investigated. MB can be hybridized with CuSCN by adding into electrolytic bath while EY cannot be independently. However, as presence of MB, EY is also loaded into the film due to make a complex with MB. In fact, adding MB and EY at 20 μM respectively, absorption peak was observed around 520 nm originated from EY. On the other hand, MB don’t hybridize with ZnO, but it can hybridize when presence of EY in the bath. The strong selection rule for hybridization was indicated. This suggests that interaction of MB and EY dyes pairs in solution leads to the formation of EY-MB pair/CuSCN or ZnO hybrid thin films. In the mixed solution, MB and EY formed dye pairs in the ratio of 2:1, and the maximum dye loading ratio in the electrodeposited hybrid film was also MB:EY = 2:1. These results indicate that MB-EY pairs hybridized with CuCSN and ZnO by electrodeposition. The optical properties of the MB-EY pairs are discussed using the obtained MB-EY/inorganic semiconductor hybrid thin films. [1] Yuki Tsuda et al., Monatsh. Chem., 2017, 148, 845 [2] T. Yoshida, et al, Adv. Funct. Mater. 2009, 19, 17

Resume : Extreme confinement of materials is achieved by encapsulating them within single-walled carbon nanotubes (SWCNTs). These low dimensional structures are investigated using a number of characterisation techniques and shown to exhibit significantly different behaviour to the materials in their bulk form. ADF-STEM images of carbon nanotubes filled with magnetic dihalides display distinct regions of highly aligned crystal growth which are confirmed by Fast Fourier transforms (FFT) and multislice simulation software as well as experimental and simulated electron diffraction patterns. A combination of thermoanalytical techniques and electron microscopy has been used to characterise the thermal behaviour of SWCNTs successfully filled with phase change materials such as antimony(III) telluride. Additional further work involves the discussion of various growth strategies of such structures via the refinement of the filling procedures used. A novel pelleting method suggests that close proximity fillings are successful at controlling the stoichiometry and homogeneity of the final structures obtained. Both EDX and XRD studies are used to characterise these materials. With regards to investigating the functional properties of confined nanowires, the removal of extraneous material is achieved using an acid reflux technique required to produce thin film samples for further measurements.

Resume : Assembling microparticles into one-dimensional (1D) particle structures formed outside liquid environment is challenging. This hugely hinders the possible applicability of such structures and development of new materials and devices. Here, we demonstrate a simple, efficient and easy to implement method for fabricating single-particle-thick chain-like structures. We provide the basic features of the electric approach for bottom-up assembly that expands the current knowledge in this area. Electrically conductive particles, initially dispersed in a nonpolar and weakly conductive liquid, are pulled out of the liquid using an electric field supported by the capillary interactions. We study in detail the role of capillary and electric interactions, viscosity and ionic conductivity of the dispersing phase, particle shape, size and density, and rate of pulling, on the general performance of the method. Our experimental results reveal that different types of microparticles (solid, core-shell, soft particles) of different shapes (spherical, disc- and ellipsoidal-like) and of any density can be assembled within seconds to form long chains. The particles need no special treatment (functionalization) to form a stable 1D structure after the process of their formation is finished. This is owned to the attractive interaction of capillary liquid bridges formed between neighboring particles. We also found that capillary forces help aligning particles and creation of single-particle-thick structures preventing formation of agglomerates. Furthermore, we estimated the optimal pulling conditions (i.e., the pulling velocity) that is influenced by the particle size and liquid viscosity. The results show that dispersing liquids with larger viscosity and lower ionic conductivity are preferred, as they reduce the negative effect of ionic screening affecting the strength and frequency of the applied electric tension. In the second part of our research, we investigate the physical properties (e.g., mechanical or electrical properties) of the produced beaded structures, as we find it intriguing from the perspective of both the fundamental research and applied research. We finally demonstrate that the 1D particle structures can be used to design new materials, for example, electrically conductive micropaths. This work was supported by NCN grant SONATA 2019/35/D/ST5/03613 to K. G. and OPUS 2019/33/B/ST5/00935 to Z. R. and Y. H.

Resume : Layered transition metal dichalcogenides (TMDCs), whose physical and chemical properties can be modified by the number of layers within the atomic thickness range, are emerging as an essential active interlayer for future nanoelectronic devices based on van der Waals (vdW) heterostructures. Here, we show the atomic spalling of vdW crystals that achieves large-area TMDCs (MoS2, MoSe2, and WSe2) with a controlled number of layers. Unlike typical 3D covalent network solids, the TMDCs are layered crystals featuring strong in-plane covalent bonding and weak out-of-plane vdW interaction, which allow the crack propagation depth to be reduced to the atomic scale. By adjusting the residual stress of the stressor film, we precisely controlled the crack propagation depth at a scale corresponding to the monolayer thickness of the TMDCs. Consequently, continuous monolayer, bilayer, and trilayer TMDCs were selectively separated from the natural vdW crystals. The presented results show huge potential for the manufacture of layer-engineered high-quality vdW materials, which can be developed into practical functional electronic and photonic devices

Resume : Herein, an N-CQDs/MoS2 (0D/2D) hybrid quantum heterostructure based broad range (UV to NIR) photodetector has been constructed with two-dimensional (2D) layered MoS2 and zero-dimensional (0D) Nitrogen doped Carbon quantum dots. The fabricated heterostructure offers good optical and optoelectronic properties. A significant photoresponse has been observed for the incidence of all three UV, visible, and NIR radiations. The fabricated heterostructure gives responsivity of 4.31 AW-1, 26.73 AW-1, and 20.72 AW-1 at 325 nm, 532 nm, and 1064 nm wavelengths. Recorded response time (133.33 ms/47.59 ms (τr/τd)) demonstrates that the fabricated heterostructure responds fast to all three radiations. Also, the fabricated heterostructure provides a relevant power conversion efficiency of 4.06 % and an enormous open-circuit voltage (Voc) of 0.83V with an excellent external quantum efficiency spectra. This work on N-CQDs/MoS¬2 (0D/2D) hybrid quantum heterostructure based broad range photodetector and photovoltaic cells would a revolution on the path of fabrication of lightweight and low-priced photovoltaic devices for the next-generation broad range photodetection and energy harvesting applications.

Resume : Surface-enhanced Raman scattering (SERS) is a method of ultra-sensitive vibrational spectroscopy that is currently being very actively researched because of its wide application range [1]. Usually, some metal nanoparticles are used, whereas low-dimensional metal nanoparticles like Au have distinct optical properties in the visible spectrum due to the activation of collective electron oscillations known as surface plasmon resonance [2]. Besides noble metal structures also semiconductors like ZnO have been studied as one of the promising SERS substrates due to their specific benefits over noble metals [3]. For both materials (metals and semiconductors) SERS phenomenon is explained by two types of important enhancement mechanisms: electromagnetic enhancement (EM) and chemical enhancement (CM), therefore, the SERS activity of semiconductor ZnO can be improved in both ways. The EM is widely known to be caused by an increased local electric field generated by the collective resonance of surface plasmons in metallic nanoparticles under incoming laser irradiation. The local surface plasmon resonance and "hot spots" effect in metallic nanoparticles are the reasons why the electromagnetic enhancement of noble metals is much larger than that of semiconductors [2]. Despite the promising applications, different ZnO systems lack systematic studies and an understanding of enhancement mechanisms is not complete. ZnO forms different shapes like tetrapods and nanowires. Such shapes drastically increase surface area. Thus in our approach, the backbone for metallic nanoparticles and "hot spots" could be branched ZnO nanostructures (tetrapods) and randomly oriented ZnO nanowires. ZnO tetrapods and nanowires were synthesised using SPVD and Microwave-assisted hydrothermal methods. Obtained ZnO tetrapods and nanowires were applied to the surface of two different substrates. 10x10 mm samples were coated with gold nanoparticles by the thermal evaporation method. Scanning electron microscopy and Raman spectroscopy were used to investigate Au-coated ZnO nanostructures. SERS activity was evaluated using Rhodamine B. Different ZnO and Au deposition strategies were tested to prepare structured films, and their SERS efficiency was compared. Most efficient structures and optimal ZnO and Au concentrations were found. According to our results, Au nanoparticle-coated ZnO tetrapod and ZnO nanowire substrates enhance SERS activity and can thus be used as low-cost, high-efficiency SERS-active substrates. The authors gratefully acknowledge the financial support of the European Regional Development Fund project Nr. 1.1.1.1/21/A/053 realised at the Institute of Solid State Physics, University of Latvia. References: 1. Sinha, G., Depero, L. E., & Alessandri, I. (2011). Recyclable SERS substrates based on Au-coated ZnO nanorods. ACS applied materials & interfaces, 3(7), 2557-2563. 2. Podila, R., Chen, P., Reppert, J., Rao, A. M., & Ke, P. C. (2011). Biomolecular sensing using gold nanoparticle–coated ZnO nanotetrapods. Journal of materials research, 26(17), 2328-2333. 3. Yang, L., Yang, Y., Ma, Y., Li, S., Wei, Y., Huang, Z., & Long, N. V. (2017). Fabrication of semiconductor ZnO nanostructures for versatile SERS application. Nanomaterials, 7(11), 398.

Resume : From humble beginnings as an industry grade pigment, TiO2 as a semiconducting metal oxide has been thoroughly researched. Advanced applications in water treatment (photocatalysis), water splitting, sensors, self-cleaning surfaces, UV-blockers in sunscreens, batteries show the shear versatility and the popularity of this compound. Due to its non-toxicity, good mechanical and chemical stability, opto-electric properties it has also found its way into third generation solar cells, i.e. TiO2 is used as an electron transport layer in dye-sensitized solar cells (DSSC), organic solar cells (OSC) and perovskite solar cells (PSC). PSC are a promising new photovoltaic technology that offers different chemical or physical synthesis routes with the only drawback being the need of fabrication in inert atmospheres like gloveboxes filled with Ar or N2 due to their sensitivity to oxygen and humidity. However, their highest selling point is their leap in efficiencies from 3.8% in 2009 to 25,2% in 2022 [1], and the low quantity of material needed for fabrication. Most common PSC are comprised as follows: substrate (conductive metal oxide glass, e.g. FTO or ITO), electron transport layer (ETL), perovskite active layer (active layer), hole transport layer (HTL) and finally an evaporated thin film metal contact (Au, Ag). When photons pass through the PSC, the ones with sufficient energies excite the active perovskite layer and electron-hole pairs are generated. These photogenerated species have to be separated, transported and collected by the electrodes (conductive oxides on glass and evaporated contacts) on both sides for the cell to produce electricity. This is separation and transport of charges is done by the aforementioned ETLs and HTLs due to their intrinsic electric fields and interface interactions with the active layer. A huge point of interest in PSC technology is the use of nanostructured ETLs as a potential way to increase the contact surface between the layers, to mitigate lower electron diffusion lengths (than the ones of holes) in perovskites, thus improving the separation of charges and finally increasing the conversion efficiency of PSC. TiO2 nanotubes are a 1D nanostructure that is especially interesting due to their high aspect ratio, porosity, elongated morphology and thin walls that facilitate electron transport down their tubular shape [2]. In this work, we present the optimization process of transparent thin film TiO2 nanotubes (TNTs) for the use as an ETL for PSC. They were prepared by anodizing Ti thin films deposited by magnetron sputtering. Different film thicknesses, anodization parameters, pore-widening techniques, perovskite concentrations, were implemented which were later correlated with opto-electric properties (for TNTs), J-V curves and external quantum efficiencies (for solar cells). Also scanning electron microscopy was used to track any potential changes in morphology during the TNT optimization. Regarding our optimization process in this work, we managed to optimize our system from a modest starting efficiency of 5% to up to 14% efficiency which is among the top efficiencies regarding perovskite solar cells containing thin film TNT ETLs published in current literature [3]. Literature: [1] https://www.nrel.gov/pv/cell-efficiency.html [2] U. Thakur, R. Kisslinger, K. Shankar, One-dimensional electron transport layers for perovskite solar cells, Nanomaterials 7 (2017) (5) 95. [3] P. Qin, M. Paulose, M.I. Dar, T. Moehl, N. Arora, P. Gao, O. K. Varghese, M. Grätzel, M. K. Nazeeruddin, Stable and efficient perovskite solar cells based on titania nanotube arrays. Small 11 (2015) (41) 5533–5539.

Resume : Due to the ease of fabrication and pronounced magnetic response, colloidal iron oxide nanoparticles have a wide range of applications, including magnetic recording media, magnetic resonance imaging, ferrofluids, as well as cancer treatment, and other biomedical applications [1]. One of the easiest and most common approaches to obtaining such nanoparticles is the use of the co-precipitation method [2]. In this method, iron oxide is precipitated from the water solution of Fe2+ and Fe3+ ions, due to the addition of the OH- groups with ammonia hydroxide. In the next step, the nanoparticles are stabilized using surfactants, which prevent flocculation. This approach allows the fabrication of nanoparticles with various shapes and sizes, as well as different stoichiometry. These parameters strongly influence the magnetic properties of the fabricated nanoparticles, such as the saturation magnetization and the blocking temperature. In this communication, we show the results of structural and magnetic measurements performed on colloidal iron oxide nanorods stabilized by tetramethylammonium hydroxide (TMAH) as well as by citric acid. In both cases, we observe a large discrepancy from the standard ferromagnetic behavior of the Zero-Field Cooling (ZFC) curve in the ZFC/FC experiment. This anomaly occurs at temperatures higher than 250K and therefore can be identified as neither the Verwey transition [3] nor the spin-glass transition [4]. We believe, that this anomaly is rather connected to the specific structure of the acquired colloid, and could be explained by a nonuniform size distribution [5], nonuniform stoichiometry [6] of the fabricated nanoparticles as well as the presence of the stabilizing agent in the sample [7]. Based on the results of Raman spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and transmission electron microscopy, the relationship between the structure of the colloidal nanoparticles and their magnetic properties will be discussed. [1] A. S. Teja, P. Y. Koh, Prog. Cryst. Growth Charact. Mater. 55, 22-45 (2009) [2] A. G. Niculescu, C. Chircov, A. M. Grumezescu, Methods 199, 16-27 (2022) [3] M. Bohra, N. Agarwal, V. Singh, J. Nanomater. 8457383 (2019) [4] B. Martinez et al., Phys Rev. Lett. 80, 181-184 (1998) [5] G. Campo et al., Chem. Mater. 27, 466−473 (2015) [6] E. Wetterskog et al., ACS Nano 7, 7132–7144 (2013) [7] V. N. Nikiforov, BRSPEX 78, 1075-1080 (2014)

Resume : Human breath is a mixture of hundreds of gases containing inorganic molecules, such as nitrogen oxide (NO), ammonia (NH3) or carbon monoxide (CO), along with other volatile organic molecules such as acetone, ethane, and isoprene. A few of these gases are produced by the body because of physiological processes. These gases are known as "biomarkers" and can indicate either metabolic health or disease within a patient. As a result, abnormal intensities of these biomarkers in exhaled breath may benefit the detection and diagnosis of such illnesses, as well as provide an opportunity to study a patient's biophysical and physiological reaction to various factors. There are currently few tests for measuring such biomarkers in human breath. Zinc oxide (ZnO) is a promising gas sensing material in terms of its long-term stability and response characteristics. Additionally, nanostructure fabrication can improve ZnO gas sensors' sensitivity and response speed. In this paper, I have studied and developed a ZnO nanostructured based gas sensor for sensing biomarkers for future integration into healthcare products. This report presents proof-of-concept of the fabricated gas sensor on a rigid substrate. The nanostructured material synthesis, device fabrication, material characterization, gas sensitivity and selectivity performance have been investigated. Several procedures have been followed to integrate the ZnO nanoparticles on fibres. In collaboration with ABENA A/S, the experiments would be repeated on diaper fabric to build smart diapers for improving healthcare management facilities.

Resume : For InP, GaAs and other III/V nanowires growth typically different methods are used, including MOVPE (metalorganic vapour phase epitaxy) and MBE (molecular beam epitaxy). In this work we used MOVPE. In order to grow various III/V nanowires, we used either gold or no gold catalyst, in the second case indium or gallium droplets were used as a catalyst. The conditions in the reactor chamber have to be kept in a very strict range in order to achieve nanowires. Otherwise cones or pillars will occur. According to Robyn L. Woo et al. [1], at a temperature of about 350 °C, nanowires are produced with a fixed diameter regardless of their length. At about 395 °C, nanocones are formed, and finally at a temperature higher than 400 °C, nanopillars can be formed. Increasing the growth temperature and keeping the V/III mole ratio constant causes the formation of conical and pillar-shaped nanostructures rather than wires. Finally, the height of the nanostructures decreases with the reduction of metalorganics flux used. These data show that nanowires grow best at low temperatures (below 400 °C) and at a low V/III mole ratio. If too much TMIn, TMGa and so on is being delivered into the reactor chamber and the V/III ratio is too high, there will be the a rapid increase in nanowire thickness but the length of the nanowires will remain the same. When there are not enough III group atoms in the reaction zone of the reactor, the nanowire thickness rapidly decreases. In order to grow higher nanowires of a stable thickness along the nanowire, one needs to increase either the time of growth of the nanowire or the flux of group III atoms used. Here in our work, III-V nanowires were grown in an AIXTRON AIX 200/4 reactor. We used indium phosphide (InP (111)B), gallium arsenide (GaAs (111)B), as the substrates. First the temperature was raised to 650o C and the heating of the substrate took place. Then the temperature was decreased and the nanowires were grown in 370 - 390o C. We used hydrogen or nitrogen as carrier gases. All the nanowires were characterized by SEM, XRD and Raman measurements. The nanowires achieved are going to be used as substrates for SERS (Surfaced Enhanced Raman Spectroscopy) measurements in the future. Literature [1] 16 - R. L. Woo, L . Gao, N. Goel, M. K. Hudait, K. L. Wang, S. Kodambaka, R. F. Hicks, Kinetic Control of Self-Catalyzed Indium Phosphide Nanowires, Nanocones, and Nanopillars, Nano Lett., 9 (6) (2009) 2207-2211, https://doi.org/10.1021/nl803584u

Resume : Over the last decades, excessive and unconscious use of water in all related fields resulted in deterioration of clean water resources. Shortage of clean water scarcity paved a way for new emerging and advantageous desalination technologies such as, Capacitive deionization (CDI). CDI doesn’t need high pressure pumps, heat sources or high energy to maintain desalination process one of the focuses of CDI research is the improvement of surface area of the electrode materials. However, using a high surface area and 3D backboned conductive network of mesoporous electrode materials remained elusive. Herein, we suggest the decoration of titanium carbide (Ti3C2) MXene flakes on commercial sponges to make sponges conductive. Decoration of MXene flakes on a highly porous sponges results in both benefiting from centimeter sized conductive mesoporous MXene and increasing the desalination rate by providing more water-MXene contact surface area. Thorough analysis including electrochemical characterizations based on energy storage is presented in conjunction with their desalination performance of the fabricated electrodes.

Resume : Titanium sulfide, TiS3, belongs to the class of two-dimensional van der Walls materials. In addition, this material is characterized by a very strong anisotropy of optical, electrical and thermal properties in the layer, which allows it to be treated as a one-dimensional material [1]. TiS3 is considered a very promising material in the field of optoelectronics because it has advantages over the most used silicon and the most touted single-layer graphene. TiS3 has a direct energy gap of about 1 eV [2]. This work presents the results of Raman and luminescence tests as a function of the polarization of the excitation and scattered beams. The measurements showed a strong dependence of the Raman scattering anisotropy and luminescence on the energy of the excitation beam and sample thickness. The research was carried out on very thin TiS3 flakes and wires obtained by micromechanical exfoliation. The samples prepared for measurements had a thickness from several to several dozen nm. As the basic substrate for exfoliation, a silicon wafer was used, with SiO2 oxide thickness of about 300 nm. [1] Zhen Lian, Zeyu Jiang, Tianmeng Wang, Mark Blei, Ying Qin, Morris Washington, Toh-Ming Lu, Sefaattin Tongay, Shengbai Zhang, and Su-Fei Shi, Appl. Phys. Lett. 117, 073101 (2020); https://doi.org/10.1063/5.0019828 [2] Abhinandan Patra and Chandra Sekhar Rout, RSC Adv., 2020, 10, 36413, DOI: 10.1039/d0ra07160a

Resume : TiS3 is a material that has aroused interest in the last few years. It’s semiconductor with direct band gap of about 1 eV, which is similar to the value of silicon band gap and becoese of that is considered as potential for electronic applications integrated with silicon electronics, thin film solar cells or near-IR detectors [1]. It belongs to the class of materials with a layered structure in which individual layers interact with each other using weak Van der Waals forces. In this work, we present the results of growth of TiS3 single crystals by chemical transport method carried out in different temperatures and the amount of transporting agent. Micromechanical exfoliation of obtained single crystals were carried out in order to obtain thin, high quality layers. Raman spectrometry and scanning electron microscopy with EDX were used to identify the obtained crystals and layers and to determine their quality. Atomic force microscopy was used to determine thickness of the exfoliated TiS3. The optical properties of the obtained materials were examined by ellipsometry and luminescence measurements. [1] Yao, H.; Liu, L. Nanomaterials 2022, 12, 325. https://doi.org/10.3390/nano12030325

Resume : Silicon wafer when combined with various surface modification techniques is explored as a SERS substrate with interesting properties. The plasmonic effect is provided by colloidal silver nanoparticles (AgNPs) synthesized in lab. At first silicon wafer is undergone femtosecond laser irradiation to ablate out micrometre sized pits and channels on the surface. AgNPs later drop casted on the surface, gets collected in these pits and channels to generate hotspots at defined locations, thereby helping out the user in quick SERS based sensing of analytes, in this case, Rhodamine 6G (R6G). While micro-pits were able to give a uniform SERS intensity throughout, micro-channels gave a rather uneven enhancement along the ablated path. The background signal generated from possible silica nanoparticles formed in the ablated region has supposedly decreased the signal-to-noise ratio. Outside the ablated region, the remaining of the AgNPs dried in a coffee ring from where we obtained very high signal enhancement. The comparatively more hydrophobic nature of Silicon surface w.r.t plane glass slide, helps in the formation of a better coffee ring with highly plasmonic active edges. This led us to the second part which involved the study of surface treatment of Silicon wafer and its effectiveness in SERS experiments. Hydrophilicity of Silicon wafer was increased via silane treatment and the same AgNPs were drop casted along with R6G. This was compared with a hydrophobic Silicon wafer with the same experimental procedure. While we obtained SERS signal from the latter as expected, we failed to obtain any peaks other than fluorescence from the hydrophilic Silicon surface. Clearly, hydrophobic nature is favouring the signal enhancement as it naturally drives the liquid containing AgNPs and dye to accumulate along the edges. The experiment was repeated with increased liquid volume as well as higher percentage of AgNPs. More amount of liquid resulted in thicker edges, which did not aid in the signal enhancement of the lower concentrations. This could also imply that improving the hydrophobicity might be futile with this method of experiment. Additionally, when the ratio of AgNPs to dye was changed from 1:1 to 5:1, it resulted in smaller dried islands rather than a big coffee ring. SERS was not observed from any such locations. Further improving the hydrophilicity might help in providing enhancement. Morphology changes like etching could help trap the AgNPs in the corrugations to create a more uniform platform, but this part is left for future exploration.

Resume : Preparation of hybrid nanomaterials such as graphene nanoplatelets (GNPs) and carbon nanotubes (CNTs) in dispersion form is a powerful strategy towards designing functional materials in a fast, simple, low-cost process and with low material waste in a scalability way. The combination of GNPs / CNTs inks are the new form of hybrids creates functional materials can be used in next-generation electronics, sensors, environmental and energy applications. Although developing flexible electronics by ink jet printing is very promising for advanced materials technology, producing high quality, well-dispersed, particle size controllable, non-agglomerated stable inks is a very challenging process. In this study, CNT, GNP, binders and surfactants are used to formulate hybrid inks. For investigation the effect of physicochemical properties on electrical conductivity, different formulas with non-functional (CNT) and -COOH functionalized multiwall CNTs (f-CNT) are prepared. Operation and formulation parameters such as amplitude, duration of sonication, concentration range, mixing temperature are optimized to control the agglomeration, viscosity, particle size and stability of dispersions. Also, Z parameter which is a printability factor of dispersions is enhanced to obtain stable printing surface tension and viscosity of the ink for fluidification performance from ink-jet nozzle. The hybrid inks are printed as layer by layer on the polyethylene terephthalate (PET) substrate which is cleaned by alcohol (70%) and plasma treatment. In order to improve conductivity properties of ink dispersions 1D (CNTs) and 2D (GNPs) nano carbon materials are used to create synergistic effects by bridging interfacial charge. Clarifying the attributes affecting the print quality and electrical conductivity, various analyzes and characterizations are performed on prepared samples. As a preliminary study, the one-week stability of CNT/GNP and f-CNT/GNP ink samples are investigated, and Tyndall effect is observed in all samples. For further characterizations; Uv-Vis., FT-IR, Raman Spectroscopy, XPS, Zeta Potential, electrical conductivity, viscosity measurements are done to optimize process and formulation parameters.

Resume : The availability of safe and sufficient water sources is the key factor to prevent water-related diseases. The use of nanostructured photocatalysts, such as TiO2 or ZnO, represent a valid solution to solve many of the current problem involving water quality. The photocatalytic oxidation is a totally-green technology for environmental application, however it is not selective and the organic pollutants at high concentration are efficiently degraded, while pollutants at low concentration (generally the most toxic ones) are removed with less efficiency. A fascinating method for preparing materials selective for specific substances is the molecular imprinting (MI). This is a synthesis method consisting of printing of a molecule (called "template") onto a matrix during its preparation, followed by the removal of the template. With this method, a molecular memory is introduced into the matrix, which becomes able to rebind the template with high selectivity. The winning idea was to match the MI with the photocatalysis, to achieve a selective photodegradation of organic contaminants. Several typologies of molecularly imprinted photocatalysts are presented and their properties towards the selective degradation of pharmaceutical products or pesticides, two typical water pollutants, are deeply discussed. The results demonstrated as the MI can be used to obtain highly selective photocatalytic nanomaterials effective in the removal of water contaminants, necessary for a green transition.

Resume : Sol-gel-based titania nanoparticles (TNPs), Silica-titania nanocomposite (STNC), and zinc supported silica-titania nanocomposites (Z/STNC) are synthesized at low temperature. FESEM/EDX shows that ZNPs are homogeneously distributed in the STNC. The STNC has average roughness (Ra) ~6 nm, surface area ~340 m2 /g, pore volume ~0.24 cm3 /g, and particle size 4 nm ± 0.3 nm, which decrease down to Ra ~5 nm, large surface area 351 m2 /g, pore volume 0.4 cm3 /g, and particle size 3 nm ± 0.4 nm due to filling of STNC pores by Zn species. STNC is revealed 94% transmission, refractive index 1.34 at 633 nm, and bandgap 2.7 eV, which decreased down to 80% transmission, large refractive index 1.38, and low bandgap 2.25 eV after ZNPs doping. The Z/STNC observed high photocatalytic activity 92%, R2 ~98%, and rate constant 0.011 min−1 in the photodegradation of phenol red under UV-light irradiation.

Resume : A new method for metallic oxide nanoparticles synthesis based on microwaves vaporization of metallic wires in air is described. The output of a commercial 800 W microwave generator was coupled through an antenna to a cylindrical wave guide cavity, which can focus the microwaves in the nodal point, where a high-power density is achieved. If a metallic thin wire with a diameter lower than 1 mm is placed in the electromagnetic node, it will strongly absorb the microwaves, resulting in its rapid heating, vaporization and finally a plasma plume formation. Optical emission spectroscopy investigations indicated that a very high temperature (>40000 K) is attained in the plasma, which contains excited and single ionized atoms from the wire and the ambient atmosphere. The vaporized material was collected on a substrate placed opposite the wire, near the cavity wall. Scanning electron microscopy, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy investigations showed that the collected material consisted of stoichiometric and single crystal metal oxide nanoparticles. The structure, chemical composition and shape of these nanoparticles is ideally suitable for their use as catalysts.

Resume : Indium-doped zinc oxide (In:ZnO) nanocrystals are successfully produced by a simple refluxed sol-gel technique. The influence of post-heat treatment/ annealing temperatures on the structure, morphology, optical and luminescence properties of nanostructures was investigated using X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM), transmission electron microscope (TEM), energy dispersion X-ray spectroscope (EDS), UV–Vis and photoluminescence spectroscopies (PL). The XRD results revealed that the synthesized In:ZnO materials are nanocrystalline with predominant hexagonal wurtzite structure. The average crystallite sizes and lattice constants of the In:ZnO nanoparticles increase with an increase in annealing temperature. SEM micrographs confirmed the nanostructure of the material and showed that the morphologies of In:ZnO nanoparticles varied from prism-like to spindle-like and then to disk-like structures. The reflectance band edge shifted towards longer wavelength while the band gap energy reduced with an increase in annealing temperature. In addition, the PL spectra show a sharp UV and broad yellow-orange emissions in the visible range that shifts slightly due to the influence of annealing temperature. The results illustrate that an optimum property of In:ZnO nanomaterial can be produced when the samples are annealed in the temperature range of 500 to 600 oC.

Resume : A blue light-emitting conjugated polymer, namely aryl-polyfluorene (aryl-F8), having a high neat-film photoluminescence quantum yield (73%) and radiative decay rate (2 × 109 s-1) is reported. Excimer emission from the polymer is significantly reduced in its neat film unlike many other wide band-gap blue-emitters achieved as a result of the bulky aryl groups attached in the polymer chain. Amplified spontaneous emission (ASE) under optical excitation is observed in pristine film at an excitation fluence, Eth ~ 3 μJ cm-2, which is one of the lowest among polymer-based optical gain media in this spectral range, reported so far. The well-separated spectra of stimulated emission and long-lived triplet absorption and very low triplet yields explain the achievement of a low ASE threshold. Under electrical excitation, no singlet-triplet annihilation (STA) is detected in the light-emitting diode (LED) fabricated with this polymer in a hybrid structure. Thus, aryl-F8 emerges as an attractive optical gain medium for lasing application.

Resume : Quantum dots (QDs) or semiconductor nanocrystals with tunable photo-optical and chemical properties are ideal to efficiently photo-catalyze many types of relevant reactions for energy conversion and organic synthesis. Cadmium sulfide quantum dots are the most studied and have received extensive attention for various photoredox reactions due to their suitable band gap and their high quantum yield. However, their toxicity and the ban of the use of cadmium in the EU have motivated the development of environmentally friendly alternatives. Indium phosphide is particularly promising thanks to its low intrinsic toxicity and theoretically emitting capacity in the entire range from the visible to the near infrared. However, few reports describe their catalytic activity and feature their poor reusability in homogenous catalysis. The main objective of this study is to demonstrate the potentiality of indium phos-phide semiconductor nanocrystals as a heter-ogeneous photocatalyst by incorporating them in mesoporous silica and graphene materials with high surface area. The size effect of the InP QDs on the catalytic performances will be studied. Then, we will present here the successful incorporation of the InP QDs in different functionnalized support materials and a first serie of reactions demonstrating their photocatalytic activity.

Resume : Polydopamine (PDA) is a mussel-inspired multifunctional polymer with a broad range of applications for biomedical and environmental purposes, (photo-)catalysis, sensing, photonics and optoelectronics. Recently, we have employed a combination of contactless optical techniques to show that pure PDA nanomembranes can also exhibit fast light-driven motion [1]. Light-induced heating of PDA leads to desorption of water molecules and contraction of membranes in less than 140 μs. Switching off the light leads to a spontaneous expansion in less than 20 ms due to heat dissipation and water adsorption. The same type of motion, which resembles pseudo-Negative Thermal Expansion (NTE), can be driven by changes of temperature, moisture and pressure, albeit in a non-local and slower manner. This behavior is attributed to the lamellar-like structure of PDA [2] and the weakening of intermolecular interactions upon water adsorption. Our findings demonstrate that PDA nanomaterials can be harnessed as robust building blocks for soft, micro- and nanoscale photoactuators, nanorobots and artificial muscles. References: [1] T. Vasileiadis, et al. Fast Light-Driven Motion of Polydopamine Nanomembranes. Nano Letters, 2022, 22(2), pp. 578–585. [2] T. Marchesi D'Alvise, et al. Ultrathin Polydopamine Films with Phospholipid Nanodiscs Containing a Glycophorin A Domain. Advanced Functional Materials, 2020, 30(21), 2000378.

Resume : The generation, manipulation and detection of light is a key requirement for a wide range of technologies reaching from consumer electronics to communication via fiber optic cable and state-of-the-art sensors. Thus, this field is in the constant focus of further technological advancement. Recent discoveries on the design of chiral metal-organic perovskites now promise cheap, sustainable materials for energy efficient generation and detection of polarized light.[1-3] However, so far, the available pool of chiral perovskite materials is rather limited. Here, we demonstrate chirality transfer effects between the one-dimensional semiconductor dimethylammonium lead iodide (DMAPbI3) and an enantiomerically pure amino acid, which cause the the previously achiral semiconductor to display chiral properties. Amino acids represent a diverse group of organic compounds whose application for industrial production is highly desirable as they are non-toxic, biodegradable and are available in large quantities at relatively low cost. We utilize the chiral small organic 3-aminobutyric acid for surface modification of DMAPbI3 using a simple spin-coating-based approach. We find that the resulting compound displays strong circular dichroism effects in the blue spectral region, which can be adjusted in their intensity by varying synthetic parameters. Furthermore, we perform an extensive structural investigation into the origin of these phenomena utilizing XRD and GIWAX experiment. We also study the effects of synthetic parameters on material performance using in-situ optical spectroscopy methods, monitoring the film formation throughout the spin coating process. Our findings provide a novel approach to introducing chiral properties into hybrid perovskite materials and hence present a fresh strategy for the design of functional thin film materials. Additionally, the give insights into the structural origins of effects relating to optical activity and provide synthetic strategies for maximizing these optical properties. [1] G. Long, R. Sabatini, M. I. Saidaminov, G. Lakhwani, A. Rasmita, X. Liu, E. H. Sargent, W. Gao Chiral-perovskite optoelectronics. Nat. Rev. Mater. 5, 423–439 (2020). [2] B. Thaom, X. Gao, K. Pan, J. Deng Chiral Helical Polymer/Perovskite Hybrid Nanofibers with Intense Circularly Polarized Luminescence. ACS Nano 15, 7463-7471 (2021). [3] C. Chen, L. Gao, W. Gao, C. Ge, X. Du, Z. Li, Y. Yang, G. Niu, J. Tang Circularly polarized light detection using chiral hybrid perovskite Nat. Comm. 10, 1927 (2019).

Resume : Cathodoluminescence (CL) spectroscopy has become a powerful tool to investigate nanostructures due to its high spectral and spatial resolution down to (sub-)nanometre. More recently, CL technique has also been used for second order auto-correlation measurements (g2(τ)) to identify single photon emitters and photon bunching in various materials. In this work, photoluminescence (PL) and CL spectroscopy as well as PL- and CL-g2-measurements have been utilized to study the quantum emission statistics of colour centres in nanodiamond in three different regimes, (i) a large ensemble of Germanium vacancies-centres (GeV), (ii) a single photon emitter, and (iii) a few colour centres. In the single photon emitter case, anti-bunching of down to 0.06 is observed for both techniques. However, for an emitter ensemble, the type of excitation – photons or electrons – can affect the emission properties drastically. While in PL, the emitter dynamics in regime (i) and (iii) always follow the Poissonian statistics (g2(0) = 1), in CL, a synchronisation of quantum emitters (photon bunching) can be achieved for incoming electrons that are sufficiently separated in time. Therefore, the degree of resulting photon bunching is strongly dependent on the applied electron-beam current (IB) with the maximum bunching factor at lowest IB. In regime (i), photon bunching is only observed for IB below 22 pA, whereas for higher IB, g2(0) converges to 1 which is similar to PL results. More importantly, in regime (iii), the photon statistics can be readily changed from photon bunching to anti-bunching by increasing the applied IB, confirming experimentally that electron-beam excitation provides a control of g2, and thereby allowing for tunability of such quantum sources.

Resume : A microcavity OLED, consisting of a conventional OLED stack with two metallic mirror electrodes, shows narrow-band emission centered around specific peak resonant wavelengths. These cavity modes are analogous to the energy states found in any resonator system, including musical instrument strings and 1-dimensional quantum square wells. We demonstrate how the microcavity OLED can be used as a unit cell in a planar, 1-dimensional photonic crystal and explore how the dimensional and material properties of the device impact the spectral electroluminescence dispersion. Stacking N microcavities splits the resonant modes into N discrete states; a photonic band centered at the single microcavity state. Devices are fabricated by thermal evaporation with in-vacuo shadow mask transfers to enable parallel-connected unit cells. The photonic density of states is controlled by varying the thickness of the semitransparent metal mirror electrodes. A Peierls bandgap is tuned by varying only alternate mirror thicknesses. Device parameters, including N, the thickness of the semi-transparent metal electrodes, and dipole emission position are correlated to emission properties such as peak wavelength, FWHM, and Q-factor for each of the photonic states. The band structure is optimized by employing optically similar silver alloys as anode and cathode. The experimental results are guided by a predictive computational modeling tool, which is critically important for the complex-architecture devices.

Resume : Chemical passivation of semiconductor surfaces (such as silicon) can be achieved by terminating the surface-dangling bonds with a monovalent atom such as hydrogen (i.e., Si–H). Such passivation leads to a decrease in the surface states within the electronic bandgap. Here we report the first observation of a constant surface dipole induced by a hydrogen atom, regardless of the band bending, carrier concentration, and doping type. The constancy in the surface dipole results from homogeneous hydrogen termination of the surface-dangling bonds and the generated equilibrium between the surface and the bulk. To this end, we systematically investigated the surface state type (acceptors or donors), the minority carriers, the work function, the electron affinity, and the surface photovoltage. Examining the ingredient for a hydrogen-induced constant and negative surface dipole opens the possibility of a negative electron affinity for Si, which has not yet been revealed. This constant and negative surface dipole makes the work function independent of the Fermi level position and controls any formed heterojunction junction rather than the space charge region. This directly impacts the ability not only to eliminate electronic defects at semiconductor interfaces, critical for microelectronics, but it also provides the means to develop heterojunctions and photo-electrode materials, and it provides control of surfaces for other surface chemistries.

Resume : In recent years, flexible organic light-emitting devices (OLEDs) have received attention as excellent candidates in their potential applications in next-generation wearable devices and multifunctional intelligent systems. In particular, an active area of research has been carried out with the objective of design and synthesis of new conjugated polymers, which combine the excellent electrical and optical properties of inorganic semiconductors with the advantages of polymeric materials, such as low density, easy processability, and synthetic tunability. In this study, the fabrication and characterization of flexible organic light-emitting diode (OLED) devices by printing processes are presented. We focus on the comprehensive characterization of new synthesized conjugated polymers, such as derivatives of Anthracene and Carbazole as well as white copolymers. The optical properties of the polymers were investigated by NIR-Vis-far UV spectroscopic ellipsometry. The accurate determination of the thickness and the optical properties were derived. Additionally, the photoluminescence (PL) properties of the polymer films were evaluated revealing the characteristic emission of each material, whereas the structural characteristics were examined by Atomic Force Microscopy (AFM). Following, these materials are applied as emissive layers in OLED devices via the Slot-die coating fabrication process. The multi-layer structure of the OLEDs consisted of a flexible poly(ethylene terephthalate) (PET) substrate, an indium tin oxide (ITO) film as the anode, a poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) film as the hole transport layer, also grown by slot-die, the EML and the evaporated Ca/Ag bilayer as the electron transport layer and cathode. The electrical characteristics of fabricated OLED devices are investigated as well as the stability of the electroluminescence emission spectrum during the device operation. Finally, novel conjugated polymers possess superior color stability and exhibit a strong potential to apply to large-scale OLED devices for commercialization. Acknowledgments This research has been co‐financed by the European Regional Development Fund of the European Union and Greek national funds through the Operational Program Competitiveness, Entrepreneurship and Innovation, under the call RESEARCH – CREATE – INNOVATE (project code: T1EDK-01039).

Resume : Semiconductor colloidal quantum dots (CQDs) offer size- and composition-tunable luminescence of high colour purity. Importantly, their emission can be tuned deep into the second biological near-infrared (NIR-II) window (1,000–1,700 nm). However, applications are hindered by the low efficiencies achieved to date. Here, we report NIR-II CQD light-emitting diodes with an external quantum efficiency of 16.98% and a power conversion efficiency of 11.28% at wavelength 1,397 nm. This performance arises from device engineering that delivers a high photoluminescence quantum yield and charge balance close to unity. More specifically, we employed a binary emissive layer consisting of silica-encapsulated silver sulfide (Ag2S@SiO2) CQDs dispersed in a caesium-containing triple cation perovskite matrix that serves as an additional passivation medium and a carrier supplier to the emitting CQDs. The hole-injection contact also features a thin porphyrin interlayer to balance the device current and enhance carrier radiative recombination.

Resume : Photonic crystals (PCs), which are dielectric materials with periodic modulation of refractive index, are attracting a wide variety of research fields owing to their unique optical properties and are employed in several applications such as sensing, catalysis, and high-performance optical devices. Although PCs have enabled the detection of ions, DNAs, proteins and other molecules at very low concentrations, its ultrasensitive detection at femto- or attomolar level remains a challenge. Fluorescent PCs have enabled a hundred-fold enhancement of sensitivity. The conventional techniques for the fabrication of fluorescent PC involve the incorporation of dyes and/or semiconductor quantum dots, which complicates the fabrication process and induces toxicity within the system. Here, we report two-photon lithography (TPL) assisted fabrication of fluorescent PCs in an acrylate-monomer doped with two-photon active functional carbon-quantum dots (f-CQDs). The f-CQD serves the dual purpose of initiating two-photon polymerization reactions required for TPL and imparts an excitation-dependent fluorescence to the PC. The use of TPL enables the fabrication of complex three-dimensional PCs with enhanced optical properties. The effect of process parameters such as laser power and scan speed on the resolution of the fabricated structures and excitation-dependent optical properties of the PC have been systematically evaluated. The surface-engineered f-CQDs can be used to tailor the sensitivity of the PC towards a specific analyte. The efficient excitation and recovery of light emitted from f-CQDs embedded in PCs can result in a greatly enhanced signal-to-noise ratio for fluorescence-based detection. The proposed material system eliminates the requirement of additional two-photon initiators and other dopants required for TPL and imparting fluorescence to the structures, respectively and can be a futuristic tool for designing ultracompact smart devices.

Resume : III-V quantum dots (QDs) act as naturally bright and highly efficient quantum emitters that can generate deterministic single or entangled photons pairs. QDs embedded in a nanowire (NW) serve as a scalable platform for site-selective and geometry-controlled in-situ heterogeneous integration onto photonic waveguides (WG) - a crucial milestone for the realization of a Quantum Photonic Integrated Circuit. In the first part, we show by numerical modelling how geometrical parameters of a NW and Si-WG design influence the spontaneous emission enhancement of the QD emitter and the in-coupling efficiencies at the NW-WG interface [1]. Preliminary experiments towards the development of an integrated III-V NW-QD system are then presented. Here, we demonstrate a droplet-free site-selective epitaxy of NWs, where first data of GaAsSb/InGaAs axial heterostructures and their distinct luminescence features will be shown. Furthermore, we discuss control of Indium incorporation into the InGaAs axial segment, in order to tune the emission wavelength before optimizing the axial size, progressing towards an axial QD. [1] N. Mukhundhan, et al., Opt. Express 29, 43068 (2021).

Resume : Nanoparticles (NPs) of plasmonic materials can sustain oscillations of their free electron density, called localized surface plasmon resonances (LSPRs). Mg is an earth abundant and biocompatible plasmonic material that can resonate across the UV-visible-NIR frequencies[1], making it a good candidate for sustainable plasmonics. However, effective utilisation of this range requires careful control over their size and shape. Colloidal syntheses are a route to scalable, facile and inexpensive production of Mg NPs. We previously successfully controlled and understood the effects of reaction parameters on the nucleation and growth of Mg NPs[2]. Small NPs (~100 nm) were synthesized using a short reaction time, by decreasing the overall reaction concentration, replacing the naphthalene electron carrier with biphenyl or using metal salt additives of FeCl3 or NiCl2. Intermediate sizes up to 400 nm were obtained by varying the overall reaction concentration or with metal salt additives of different reduction potentials. Larger particles of over 1 µm were obtained at temperatures of 0 °C. However, these particles tend to aggregate, leading to difficulties with characterization and colloidal stability. Here, we show the effects of a few common surfactants in the synthesis of Mg NPs. SDS and CTAB do not have much effect on colloidal stability or average particle size. In contrast, PVP causes particles to remain in suspension for a few weeks and their average size is reduced. To further investigate how PVP affects the synthesis, reaction kinetics were investigated by varying reaction time for syntheses with and without PVP. We show that while growth rate remains comparable, final NP size is limited to an average of 240 nm by PVP compared to 400 nm with no surfactants. Building on to the controllable Mg synthesis, we aim to prepare bimetallic plasmonic NPs for photocatalysis. In such systems, the antenna-like behaviour of LSPRs can concentrate energy at a catalytic site, leading to enhanced reactivity. A convenient way to synthesize such NPs is via galvanic replacement, where Mg will spontaneously reduce metal ions with a more positive reduction potential. We show that this method produces decorations of small metal NPs that lie on the surface of the Mg NP[3] and demonstrate catalytic activity for hydrogenation reactions. [1] Ringe, E., J. Phys. Chem. C Nanomater. Interfaces, 2020, 124, 15665-15679 [2] Hopper, E. et al, J. Phys. Chem. C, 2022, 126, 563-577 [3] Asselin, J. et al, J. Chem. Phys., 2019, 151, 244708

Resume : Ge is emerging as a likely material in the next generation of high-frequency field effect transistors. However, the preparation of an interfacial layer enabling to passivate and insulate Ge surface is still problematic. A promising approach consists in designing new self-assembled molecular monolayers (SAMs) [1] grafted on Ge exhibiting highly insulating and passivating properties as new high-K self-assembled nanodielectrics [2]. We have studied SAMs of model molecules such as alkylthiols and fluoro-alkylthiols, and of specially synthesized non-charged novel push-pull chromophores bearing electron donor and acceptor groups, separated by a pi-conjugated bithiophene bridge which promotes electron transfer with dipole formation [3]. Indeed, due to the alignment of the oriented dipoles promoted by the SAM deposition strategy, such push-pull chromophores have been shown to form highly polarizable insulating films [2]. We have adapted and developed the original Ge deoxidation/grafting technique in hydro-alcoholic solution [4] and shown that, compared to the usual deoxidizing acid treatment, it gives smoother surfaces and well-organized SAMs, which is proven by ellipsometry, wettability, and scanning probe microscopy analyses. The grafting of alkylthiols and fluoro-alkylthiols on Ge has been performed directly in a single step, whereas the push-pull chromophores designed with a carboxylic anchoring group have been grafted using an amide bonding on pre-assembled amine-terminated sticking layers. Among the latter, aminothiophenol has led to better arranged and smoother SAMs than cysteamine, i.e. more suitable for grafting ordered push-pull SAMs on top. UV-Visible absorption spectroscopy of push-pull chromophores in solution was used to determine the concentration limit to avoid aggregation. X-ray and infrared spectroscopy analyses demonstrate the oxide removal from the Ge surface after the SAM formation. Statistical electrical analyses revealed that with such push-pull SAMs, we have been able to decrease the current by a factor of 105 compared to Ge, and 104 compared to dodecane SAMs of similar thickness. Results have been analyzed by transition voltage spectroscopy [5], and successfully correlated with spectroscopic analyses of molecular levels, using inverse photoemission spectroscopy and XPS valence band determination for probing the unoccupied and occupied molecular orbitals respectively, as well as with DFT calculations, thus allowing to identify the highest occupied molecular orbital as the level involved in the electronic transport through the push-pull SAM. Dipole formation has also been evidenced in the SAM. 1. A. Ulman, An Introduction to Ultrathin Organic Films, Academic Press (Ed.), Boston (1991) 2. A. Facchetti et al., Adv. Mater. 17 (2005) 1705; Y.G. Ha et al., Chem. Mater. 21 (2009) 1173 3. V. Malytskyi et al., Tetrahedron 73 (2017) 5738 4. J.N. Hohman et al., Chem. Sci. 2 (2011) 1334 5. X. Lefevre et al., J. Phys. Chem. C 119 (2015) 5703

Resume : Organic light-emitting transistors (OLETs) are optoelectronic devices capable of providing electrical switching capability and light-emitting characteristics from a single multifunctional device structure. These combined features make them attractive candidates for a wide variety of applications, ranging from displays to sensors. In order to maximize the performance of devices, the OLET ambipolar trilayer heterostructure is one of the most developed light-emitting transistor structures. However, the limited availability of electron transport semiconducting materials, in conjunction with the complex interconnection between electroluminescence and ambipolar charge transport properties, has hampered the disruptive evolution of the OLET technology. In this scenario, through the selection of compounds with tailored chemical structures, we unveiled the complex correlation between energy level alignment within the structure, morphological properties and intrinsic characteristics of the electron transport semiconductor.[1] In this context, the introduction of a proper electron injector at the emissive/semiconducting layers interfaces further highlighted the bidimensional nature of OLETs with respect to the one-dimensional operation of prototypical organic light-emitting diodes.

Resume : VO2 based thin films find a great number of energy saving and environmental applications, including energy-efficient (smart) windows, due to their capacity of controlling IR radiation and luminous transmittance at the same time. Their properties are based on the critical temperature Tc, above which VO2 exhibits metallic behaviour and possesses the desired properties. In recent years, a systematic study has been carried out to grow and monitor the properties of VO2 films on suitable substrates, such as (La0.18Sr0.82)(Al0.59Ta0.41)O3 (LSAT) or Si. Pulsed Laser Deposition (PLD) is an established growth technique for thin film metal oxides, due to the resulted crystalline quality and its versatility to numerous complex epilayer structures and multilayers. This contribution deals with the nanostructural properties of VO2 thin films grown by PLD on either LSAT or Si with variable thickness, as determined by electron microscopy methods (TEM/HRTEM) and post-experimental HRTEM image processing. Results concerning overall epilayer morphology, thickness and crystalline quality will be presented, in relation to the variable PLD growth conditions. The two distinct structural polymorphs of VO2 -monoclinic or rutile- as detected by electron diffraction and HRTEM analysis will be associated with substrate used and overall film thickness. In addition, strain measurements, by application of the Geometric Phase Analysis (GPA) technique will be presented and related to growth conditions and type of substrate.

Resume : Silver and gold nanolayers are often used in biosensors [1], metamaterials [2], multilayer absorbers [3] and other plasmonic applications. One of the most profound problems in fabricating thin and smooth Ag or Au films is their poor adhesion to the surface of oxide substrates [4]. A classic way to approach this problem is to use a wetting interlayer made of a third material with high adhesion to both the metal and the substrate. In the case of silver and gold films, one of the best and most commonly used wetting interlayer materials is germanium [5]. However, as it has been proven recently, Ge atoms migrate from the wetting interlayer through the metal grain boundaries towards the surface of the metal film [6,7]. This in turn increases the specific resistivity of the metal film, deteriorating its plasmonic properties [8]. However, the description of the segregation process in such systems is much more complex. In this communication, we show that the segregation of germanium from the wetting interlayer towards the surfaces of the Ag and Au films is a multi-stage process. At first, Ge atoms migrate into the metal grain boundaries, but do not reach the surface yet. At this stage, a significant increase in specific resistivity is observed, but there is little change in the optical response of the plasmonic film in the visible spectrum. Once the Ge atoms reach the near-surface grain boundaries, the permittivity of the metal films in the visible part of the electromagnetic spectrum undergoes drastic changes. At the last stage, Ge atoms present in the metal grain boundaries segregate to the surface of the metal, which results in a slight decrease in the specific resistivity of the film. Based on the results obtained from optical and resistivity measurements as well as Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) we discuss the causes, progress and consequences of this multi-stage behavior. We also show for the first time SEM images directly depicting the presence of high concentrations of Ge atoms in the metal grain boundaries. [1] B. Špacková et al., J. Proc. IEEE, 104, 2380–2408 (2016) [2] T. Stefaniuk et al., Adv. Opt. Mater. 5, 1700753 (2017) [3] A. Pastuszczak et al., Opt. Quantum. Electron. 47, 89–97 (2015) [4] R. Malureanu, A. Lavrinienko, Nanotechnol. Rev. 4, 259-275 (2015) [5] V.J. Logeeswaran, et al., Nano Lett. 9, 178-182 (2009) [6] A. Ciesielski. et al., Beilstein J. Nanotechnol. 9, 66–76 (2018) [7] A. Ciesielski et al., Surf. Sci. 674, 73-78 (2018) [8] T. Stefaniuk et al., Appl. Opt. 5, B237-B241 (2014)

Resume : Soft and stretchable electronics have been a promising research field for decades due to the development of diverse applications such as soft robots, stretchable sensors and actuators, wearable electronics devices, and energy devices. Stretchable conductors, a key element of stretchable electronics, have been studied until now to achieve high stretchability with negligible performance degradation and delicate patterning to fabricate simple circuitry devices. Among many approaches, using Ga-based room temperature liquid metal such as EGaIn (eutectic gallium-indium alloy, consisting of 74.5% gallium and 25.5% indium as weight percent in a mixture) is one of the promising methods due to the material’s inherent fluidity and conductivity. However, the high surface tension and the oxide skins of EGaIn make fabricating stretchable circuits challenging as electromechanical properties tend to be unstable under prolonged use on various substrates. Furthermore, the field still lacks the development of stretchable conductors with varying degrees of electromechanical properties. To overcome the weaknesses of the current proposals in stretchable conductors, we hereby present a facile-manufacturable laser-irradiated biphasic metallic composite (LIBMC) conductor with high stretchability and varying degrees of electromechanical properties depending on the laser intensity. Laser irradiation causes surface plasmon-induced photothermal entanglement of EGaIn particles (0D material) and AgNWs (1D material), forming immediate selective delicate patterning of a stretchable resistor or electrode, depending on the laser intensity, with spatially varying degrees of conductivity and strain-resistance characteristics. The gallium oxide outside the LIBMC and the AgNW core creates a robust structure, and the coated EGaIn determines the conductive properties. Furthermore, the facile and straightforward fabrication process without using toxic chemicals facilitates soft and stretchable electronics applications. We demonstrated a stretchable heater by applying a monolithically patterned LIBMC conductor as both heating wire and electrodes simultaneously. We illustrated different temperature rises in each region by the monolithic patterned heater in series, and the temperature values were consistent up to 50% uniaxial tensile condition. The compatibility of LIBMC with both regimes of electrodes, ease of manufacturing, and successful selective heating suggest a facile mode of complex, stretchable electronics production at a device level.

Resume : Transparent electrodes are of paramount importance for optoelectronic devices such as solar cells, LED or sensors that require electrical front contacts to extract carriers while transmitting light to the remaining part of the device. Indium Tin Oxyde (ITO) is the market leader, but it suffers, among other things, from strong absorption in the UV/blue spectral range and important ohmic losses that impact device efficiency and cost. Metallic interconnected nanowires or grids in the other hand offers the possibility to increase conductivity while tuning plasmon resonances to couple light into an underlying substrate and/or reduce reflectivity (Groep et al., Nano Letters, 2012; Sciacca et al., Adv Mater, 2016). However they suffer from poor material quality and limited scalability when fabricated by top-down approaches, or limited plasmon resonance engineering when using colloidal nanowires. It has been demonstrated that single-crystal silver and gold nanocubes, grown in solution phase, could be used as building blocks for the fabrication of continuous monocrystalline nanostructures via epitaxial welding of adjacent nanocubes (Sciacca et al, Adv Mater, 2017; Capitaine et al, Adv Mater, 2022). We offer to bridge the gap between scalable bottom-up solution routes and high-accuracy top-down nanofabrication by using Ag and Au nanocubes as building blocks for the realization of quasi-monocrystalline transparent electrodes by combining assembly of nanocubes into grids and epitaxial welding. Following up the work from Agrawal et al. (Agrawal et al., ACS Nano, 2020) we investigated the assembly of monocrystalline nanocube building blocks into grids by nanoimprint lithography. PVP-capped nanocubes, serving as composite ink, are first deposited on a hard surface; then a polydimethylsiloxane (PDMS) stamp, serving as template, is pressed against the surface. Nanocube lateral mobility is correlated with the amount of PVP present between the substrate and the nanocubes, quantified with sub-nanometer precision by analysing the resonance of gap plasmon cavity modes and comparing it with FDTD simulations. This provides with valuable insights on the imprinting mechanism and eventually allow the assembly of continuous Au and Ag grids over mm2 on glass. The high-quality assembly combined with previously demonstrated Au and Ag welding finally allows for the realization of quasi-monocrystalline transparent electrodes on glass, allowing for swift integration into devices upon building the rest of the stack on the glass substrate. We use SEM and conductivity measurements to provide evidence for chemical welding and compare optical and electrical measurements of the metallic grids with standard transparent electrodes. Finally, we show that Au and Ag grids can be transferred to PDMS and released to other substrates, paving the way for integration in flexible devices or in tandem solar cells that are incompatible with classic nanopatterning strategies such as perovskite layers.

Resume : The possible 2D-like arrangement of monomers in polydopamine films obtained by autoxidation of the dopamine at the air/water interface was recently reported. Therefore, the morphological and chemical properties should be controllable by tuning the synthesis conditions. This presentation shows the growth control of the films obtained at the air/water interface with different dopamine concentrations, various pH, and stirring speeds. The growth of the films was monitored in situ by spectroscopic reflectometry. The control of the growth process was achieved at the centimetre-scale level in terms of thickness homogeneity and chemical and structural characteristics of the obtained films. Transfer of the films onto substrates did not affect the homogeneity, foreshadowing an opportunity for large scalability of the process. The films are then transferred to different functional substrates showing improved photocatalytic response and promising applicability in water remediation and energy production. The authors acknowledge the financial support from the National Science Centre (NCN) of Poland by the OPUS grant 2019/35/B/ST5/00248. J.S and D.A-F. Acknowledge the Financial Support of the French Government Scholarship.

Resume : Zinc oxide nanoparticles are widely used in various fields of science and technologies. Unfortunately, own photoluminescence (PL) of the pure ZnO is mainly located in the UV range that makes it unsuitable for lightening applications, e.g. Adding of various additional components can be used to obtain defect-induced visible light PL from materials based on the ZnO matrix. In this work, we study synthesis conditions, physical and chemical characteristics of zinc oxide nanoparticles prepared by sol-gel method in environment of natural or synthetic polymers. Obtained zinc oxide nanoparticles have been analyzed by XRD, FTIR, SEM and DTA/TG. PL emission of the investigated samples is observed in the wide spectral range from 350 to 800 nm. The PL spectra are complex and consist of two types of spectral details. There are narrow band in the 350 ? 420 nm range and wide band in the 430 ? 800 nm range. The relative intensities of these bands depend on the types and concentration of polymers. The narrow UV band corresponds to the well-known ZnO exciton emission. It is suppressed in about 10 times in polymer-containing samples if compare to the samples without polymers. The wideband visible emission is complex and consists of two components of equal intensity with maxima around 580 and 650 nm and a weaker component peaked at 760 nm. Nature of these components is discussed taking into account possible types of shallow and deep defects in the ZnO crystal lattice. This work has received funding from Ministry of Education and Science of Ukraine and from the Horizon Europe research and innovation program under grant agreement No 654360 within the framework of the NFFA-Europe Transnational Access Activity.

Resume : Transparent conducting oxides are one of the most important constituents in modern thin film solar cells devices. Titanium oxide is widely used, but one of the major drawbacks is the necessity for the thermal treatment step that requires temperatures over 400 °C where zinc oxide arises as a viable alternative. ZnO can be easily derived in both mesoporous and nanostructured configurations by low cost, cheap, fast and non-toxic chemical methods. Furthermore, the properties can be improved by doping, primarily by aluminium in a cheap and efficient manner, in order to improve both electrical and optical properties. In this work we tried to address all feasible permutations of the synthesis steps by combination of sol-gel, hydrothermal and chemical bath deposition methods, with or without additional thermal treatments. The goal was to systematically compare the planar and nanostructured films, in both the effect of the morphology and the Al content on the end properties of the samples, and derivatively solar cells. The successfulness of the outcome was checked by grazing incidence X-ray diffraction, UV/VIS, Raman and Fourier transform infrared spectroscopy, scanning and transmission electron and atomic force microscopy. The electrical properties of the samples were studied in detail by means of solid state impedance spectroscopy and deep level transient spectroscopy. In conclusion, from the pragmatic point of view only few routes prove viable for preparing AZO films suitable for use in photovoltaic devices. Keywords TCO; AZO thin-films; chemical bath; wet chemistry; GIXRD; nanostructuring Acknowledgment This work has been funded by the projects PZS-2019-02-1555 by the CSF and ESF, UIP-2019-04-2367 by the CSF, and KK.01.2.1.02.0316 by the ERDF

Resume : Central to the development of optoelectronics devices based on organic materials is the availability of efficient synthetic molecular and polymeric photoswitches. The desired feature of photoswitches is photochromism, whereby two stable states are reversibly accessible using light as the external stimulus. Excited state intramolecular proton transfer (ESIPT) is a process in which the electron structure of a molecule is changed through the ultrafast movement of a proton within the molecule via photoexcitation. This effect is present in molecules with a hydrogen bond donor near a hydrogen bond acceptor. The keto tautomer formed via ESIPT possesses different photophysical properties from that of the original enol species and leads to a large Stokes shifted emission. This concept exploits excited state aromaticity where the loss/gain of aromaticity is a driving force towards fast barrierless switching. The change in aromatic on the associated ring allows for a change in conjugation through the molecule and can therefore be exploited in polymers. Polymers allow for a stronger optical response with an increased density of switches in comparison to molecular switches. They are solution processable, flexible and lightweight making them ideal for device implementation. We have synthesised a range of ESIPT monomers which include phenyl and thiophene groups for use in conductive polymers. We report the first ESIPT incorporated fluorene copolymer and characterisation of polymer series. Further work is being done to access the photophysical properties of these new materials. The development of new, ultra-fast photoswitchable polymers has implications for use throughout the entire field of nanoscience where the manipulation of material properties using light is directly linked to catalysis, energy, and biological nano-themes.

Resume : Metal halide perovskites (MHPs) nanowires and their heterostructures have shown excellent performance in various optoelectronic fields. Most of the previous studies concern MHP nanowires horizontally aligned on a substrate. As a comparison, vertically aligned free-standing nanowires have a much more suitable geometry for scalable LEDs, solar cell and sensor devices, which has been demonstrated by studies on traditional semiconductor like ZnO, Si and GaN nanowires. However, vertically aligned free-standing MHPs nanowires arrays are very rarely reported, due to the difficulty of growing such structures. A few studies have reported free-standing MHP nanowires by solution extrusion and vapor-liquid-solid methods, but the alignment of the obtained NWs was not satisfactory. The solution extrusion method works only when the precursor can form an intermediate phase, while the vapor-liquid-solid growth needs the assistance of a metal catalyst and high temperature. Therefore, a more general low temperature, catalyst-free method to grow free-standing vertically aligned MHP nanowire arrays is still urgently needed. Heterostructures are essential for electronic and optoelectronic devices, thanks to their ability to control the electronic band structure, and the ability to create MHP nanowire heterostructures would be highly desirable due to their potential applications such as multicolor displays, self-powered photodetectors, and large-scale electronic circuits. However, the epitaxial growth used to create heterostructures in traditional semiconductors is very difficult in MHPs, since the liquid precursor solution of the new layer tends to dissolve previous layers. Instead, several groups have investigated the halide or anion exchange method, where the halide atoms are replaced after crystal growth. Single nanowire or horizontal nanowire arrays with heterojunctions have been made by solid diffusion, solution or vapor anion exchange. Electron beam lithography was usually required to selectively expose parts of the nanowires before the anion exchange, but such an approach is not scalable for large-area devices. Our work successfully overcomes this challenge and we obtain free-standing CsPbBr3 nanowires by nanopore-guided growth. The nanowires first grow inside the AAO (anodized aluminum oxide) nanopores and then keep growing out of the nanopores to be free-standing nanowires. The nanowire length is controlled ~1 to ~ 20 μm with the precursor amount. Optical and electrical characterization results indicate the high quality and promising optoelectronic applications of the nanowires. As an example of how the vertical orientation can be used for scalable device processing, we also successfully obtained nanowire arrays with heterojunction by one-step vapor anion exchange method. The self-aligned and lithography-free process is used to fabricate millions of hetero-structured nanowires on a single sample. These results will promote the development of MHP nanowires and their heterostructures in the vertical direction, which is much more suitable for various optoelectronic devices.

Resume : Chemical Beam Vapor Deposition grown nanocomposite ZrO2/TiO2 thin films for high-k dielectric applications Rashmi Rani a*, William Maudez a, Estelle Wagner a, Md Kashif Shamim b Seema Sharma b, Radheshyam Rai c, Giacomo Benvenuti a,d, a 3D-OXIDES, 41 rue Henri FABRE, Saint Genis Pouilly 01630, France. b Material Research Laboratory, Department of Physics, A N College, Boring Road, Patna-800013, India. c Department of Physics, School of Physics and Materials Sciences, Shoolini University, Solan-173229, India. d ABCD Technology, Route de Champ-Colin 12, CH-1260 Nyon, Switzerland. Nanocomposite ZrO2/TiO2 thin films were deposited onto TiN/Si substrate by Chemical Beam Vapour Deposition (CBVD) technique with combinatorial approach. The structural, morphological, and electrical properties of the nanocomposite films were examined for three different element compositions (20/80, 30/70 and 40/60 at. %). X-ray diffraction pattern of all thin films showed pure phase of anatase TiO2, tetragonal phase of ZrO2 and orthorhombic phase of ZrTiO4. The prominent peak, corresponding to orthorhombic phase of ZrTiO4, was observed in the 40/60 at.%. of ZrO2/TiO2 thin film which was further confirmed by the Raman analysis. Atomic force microscopy (AFM) and Field emission scanning electron microscopy (FESEM) revealed crack free and homogeneous morphology for all the composite films. Furthermore, Surface roughness was significantly decreased with increase concentration of ZrO2. Dielectric constant of these composites was strongly dependent on ZrO2 concentration and found to be maximum (up to ~ 73) together with low dielectric loss (~0.01) and high ionic conductivity (~10^(-1)S/cm) for 40/60 at. % of ZrO2/TiO2 nanocomposite film. In addition, a low leakage current density (~10^(-7) A/cm^2) was observed for ZrO2/TiO2 (40/60 at. %). The binary composite ZrO2/TiO2 (40/60 at. %) thin film with high dielectric constant, high ionic conductivity and low leakage current density shows promise for the future applications in the high-k dielectric field. Keywords: Chemical Beam Vapour Deposition; Nanocomposite; ZrO2/TiO2; Thin films; High-k dielectric.

Resume : The design of multifunctional materials with controlled micro-features is critical for many existing and emerging applications. To achieve high-resolution 3D printing, melt electrowriting (MEW) emerged as a novel electrohydrodynamic technique that allow to deposit continuous polymeric microfibres in a very precise way. The microscale perspectives combined with a solvent-free approach and a simple fabrication process have allowed MEW to establish itself as one of the most promising techniques for high-resolution printing. Despite its clear advantages, MEW is a young technology, so there are still plenty of possibilities for exploring new materials to be printed by this technique. In particular, the use of functional fillers within the MEW-processed structures to promote active properties on it remains so limited, and just some additives have been explored with a very low emphasis on their active properties. The low size of the fibers (1-50 µm) limits the type of active fillers that can be explored, and it became clear that the use of nanoparticles to promote the active properties on it is the key due to their low sizes. In that context, this work explores the potentials of MEW for active materials printing by using different nano-fillers. In particular, conductive, thermocromic and magnetic nanoparticles are explored to confer the printed polymeric structures with conductive, optical and magnetic properties. Results demonstrate that different complex microstructures with up to 5% wt. of nanoparticles/nanotubes could be successfully printed without affecting to the printing quality. This concentration of nanoparticles results enough to provide the printed structures with the desired active properties (magnetic actuation, color change or electrical response), allowing to explore their potentials for sensors and actuators as well as for electronics. Moreover, the effect of the isotropic/anisotropic shape of the nanoparticles and the possibility of their alignment on the fibers during the printing process are also investigated. The low diameter of the jet during the printing process as well as the mechanical stretching of the fiber can favor the alignment of the1D nanomaterials on the printed structures which has huge potentials for the design of electronic devices. To conclude, the potentials for multi-material design are explored, demonstrating that multi-material structures could be successfully fabricate allowing to control the multi-active response at the microscale level.

Resume : Lifetime measurements in semiconductors are crucial for understanding the carrier properties for their various electrical applications. With various well established lifetime measurements, the effective lifetime of the majority carriers is what we usually measure. Here we demonstrate a simple technique for differentiating between bulk and effective lifetime by the phenomenon of photo-electro-magnetic effect in semiconductors. Electrons and holes (free carriers) are generated when a semiconductor is illuminated by photons of energy greater than its energy bandgap. When the absorption is strong enough, the majority of these free carriers are generated near the semiconductor's surface, which results in a concentration gradient across the thickness of the semiconductor. Consequently, diffusion of carriers occurs across this concentration gradient in the direction of illumination. When a magnetic field is applied perpendicular to this gradient, electrons and holes get deflected in opposite directions, developing a potential across the semiconductor surface in the direction mutually perpendicular to the magnetic field and illumination. This phenomenon is known as the Photo-electro-magnetic effect, and the voltage drop is the PEM open-circuit voltage. A PEM short-circuit current flows through the semiconductor when the two ends are shorted. In this work, it is demonstrated that, through proper investigation of PEM and photoconductivity effects in semiconductors, it is possible to determine various semiconductor parameters like minority carrier diffusion length, carrier lifetime, surface recombination velocity, etc.

Resume : Nanoscale materials do exhibit excellent properties suitable for many applications but their utilization in day-to-day technologies is still limited. Their very small size in the nano regime is responsible for unique properties but it also puts the boundary conditions towards their versatile utilization, often they require a substrate as support followed by a complex integration process. For appropriate use, the nanostructures need to be arranged in special 3D forms. This talk will briefly highlight the scope of complex-shaped nanostructures towards constructing sponge-like 3D nanomaterials [1]. Complex shaped nanostructure building blocks such as tetrapods exhibit the ability to construct a self-assembled 3D porous architecture. Such a 3D network is structurally and mechanically intact, offers high surface area accessibility, can be easily functionalized with any desired external molecules or nanostructures, towards multifunctional properties. Such self-supported 3D nanonetworks are thus the right candidates to translate the nanoscale features to real technologies. A brief overview about the smart materials engineering and application opportunities of tetrapod nanomaterials and their 3D networks with respect to advanced technologies be highlighted in this talk.

Resume : In this session, we will briefly summarize the following aspects: Overview of EMRS Fall 2022 Symposium K; Publications of symposium papers in various special issues/magazines; Next year's EMRS meeting details; Career dialogues with young researchers; Collaboration opportunities; Question-answer session with participants and feedbacks for future improvements; and all other necessary aspect.