Organized nanostructures and nano-objects: fabrication, characterization and applications V

Resume : Delta doping was traditionally formed by molecular beam epitaxial (MBE).[1,2] Here, we present a delta doping technique by self-assembled molecular monolayer annealed with nanosecond pulsed lasers. A monolayer of PCl3 was first self-assembled onto the patterned device layer of silicon-on-insulator (SOI) wafers. Xray photoelectron spectroscopy (XPS) indicates that the self-assembly leads to P atoms binding with Si in form of P(OSi)3. To prevent evaporation of P and possible external contamination, a 50nm thick SiO2 layer was deposited to cover the monolayer by atomic layer deposition (ALD) before a nanosecond excimer laser was applied to anneal the samples. A solid-to-liquid phase transition occurred as the laser power increases. A 20nm-thick crystalline silicon was epitaxially grown on the post-annealing samples after the SiO2 layer was removed in HF. Secondary ion mass spectrometry shows that most of dopants were driven into silicon by the pulsed laser annealing. For samples maintaining in solid phase but on the phase transition border, a high concentration (>1020 cm-3) of phosphorus dopants accumulate within a few atomic layers at the interface, forming a delta doping at atomic scale. Hall effect measurements indicate that only 30% of dopants in the delta-doping sample are electrically active. Further investigation is under way to address this issue. In short, the self-assembled molecular monolayer doping combined with pulsed laser annealing technique provides a new pathway for delta doping, which may find important applications in some niche area such as solar cells in which a delta doping is required to increase energy efficiency at the short wavelength solar spectrum.[3] References [1] N. L. Mattey, M. Hopkinson, et al, Thin Solid Films 184 (1990) 15-19. [2] K. Ploog, Journal of Crystal Growth 81 (1987) 304-313. [3] J. Day, S. Senthilarasu, T. K. Mallick, Renewable Energy 132 (2019) 186-205

Resume : Deterministic doping of semiconductors represents a difficult challenge in advanced nano-electronic devices and alternative technologies for nanoscale doping of semiconductors are highly desirable. In this talk, we will present our recent results on the doping of silicon substrate by polymers terminated with a phosphorus containing moiety, benchmarking this alternative doping technology against conventional doping approaches. Some years ago, Ho et al. proposed the so-called monolayer doping (MLD) approach based on the formation of a self-assembled monolayer (SAM) of dopant-containing molecules on the semiconductor surface.[1-4] In particular, SAMs formed by diethyl 1-propylphosphonate (DPP) were widely studied highlighting the self-limiting behavior of the grafting process [5] and the limited incorporation of C and O impurities in the first monolayers of the Si crystal lattice.[6] DPP was envisioned as an efficient dopant carrier for generating P dopant sources over deglazed and non-deglazed Si substrates.[6] In our work a diethylphosphate moiety placed at one end of polymer chains was used to graft these macromolecules on an activated Si substrate forming a brush layer.[7] The total dose of P deposited onto the non-deglazed Si substrate correlated with the degree of polymerization of the P terminated polymers.[8] An efficient protocol was proposed to remove the polymeric chain by O2 plasma without affecting the tethered P-containing moieties on the surface. Repeated grafting/ashing cycles led to a cumulative increase, at constant steps, in the dose of P atoms.[8,9] The release of P atoms from the dopant source and subsequent diffusion through the SiO2 matrix into the Si substrate were investigated, [10] achieving high activation rates (80%) of injected P atoms.[9] Integration of this technology with advanced lithographic technologies envisioned the possibility to move toward deterministic doping of semiconductors. In conclusion, a simple and low-cost bottom-up approach, based on polymers terminated with P containing moieties is proposed showing potential for the development of a mild technology for efficient doping of semiconductors. [1] J. C. Ho et al., Nat. Mater., 2008, 7, 62?67. [2] R. C. Longo et al., Adv. Funct. Mater., 2013, 23, 3471?3477. [3] J. Fu et al., AIP Adv., 2019, 9, 125219. [4] X. Gao, et al., Nat. Commun., 2018, 9, 118. [5] E. Arduca et al., Nanotechnology, 2016, 27, 075606. [6] Y. Shimizu et al., Nanoscale, 2014, 6, 706?710. [7] V. Gianotti et al., J. Anal. Appl. Pyrolysis, 2017, 128, 238?245. [8] M. Perego et al., ACS Nano, 2018, 12, 178?186. [9] M. Perego et al., J. Mater. Chem. C, 2020, 8, 10229. [10] M. Perego et al., J. Mater. Chem. C, 2021, 9, 4020.

Resume : As the size of MOS transistors is being scaled down to few nanometers, the gate-all-around transistor has become the most promising candidate for devices according to the International Roadmap for Devices and Systems [IRDS]. Vertical integration offers great promises, by moving from planar to real tri-dimensional circuit design. Junction-less architecture, where the nanowire (NW) channel is homogenously highly doped, simplifies the fabrication of the device, in particular the S/D region engineering. The focus of the paper is the engineering of free-standing homogenous doped nanostructures compatible with high performance of vertical nano-transistors. The nanostructure patterning is based on a large-scale top-down approach, including (i) nanomask structuration by e-beam lithography of a negative tone resist (ii) anisotropic plasma etching to transfer the mask into the Si substrate (iii) sacrificial wet oxidation to smooth the sidewall and decrease the NW dimension. Three configurations of samples have been studied: (S1) highly doped Si wafers (3E19 boron/cm3), (S2) localized high doped wells (3E19 boron/cm3) on high resistive (HR) wafer made by localized ion implantation and (S3, S4) HR Si wafer. The doping level does not affect the patterning of the nanostructures, but increases their oxidation rate, which is larger in highly doped samples (20 % for 50 nm of diameter, 19 % for 20 nm of diameter). Moreover, the NW patterning on localized implantation wells shows the formation of large structural defects in these areas (size = 0.4 µm, density = 1 defect/µm2) which follows the crystalline orientation of the substrate. The size of the defects is increased after oxidation, larger than 0.8 µm in width and 0.5 µm in depth. To go further, (S4) is a localized implantation, in the same condition as S3 but made after the NW patterning, which does not generate any defects and shows a perfectly defect-free surface. Finally, vertical scaled gate-all-around transistors (Gate length = 18 nm) have been fabricated on the doped nanowires obtained on S1 and S4. Both configurations show very high drive current but S4 exhibits a poor Ion/Ioff ratio (1 decade) with a high off current in comparison to S1 (Ion/Ioff ratio up to 5 decades). It is speculated that a radial dopant segregation at the NW surface occurs when the dopant implantation followed by the activation annealing at high temperature are performed after the NW patterning. This study gives some new inputs on the patterning of highly doped nanowires from basic science but also some guidelines from an integration scheme point of view.

Resume : Self-assembled monolayers (SAM) of molecules have a broad range of application: from biosensors to solar cells and thin-film transistors. SAMs of dopant containing molecules have been proposed as a mild and simple alternative to ion implantation in order to obtain conformal doping of 3D complex nanostructures. The control on the amount of dopant can be achieved varying the steric encumbrance of the molecules. Using chains of PS or PMMA with a narrow polydispersity and terminated with a P containing moiety it is possible to control the amount of P deposited onto a SiO2 surface and, iterating this process, it is possible to further increase the P deposited, in the range from 2 x1013 to 3 x1014 atoms/cm2 [1]. A subsequent thermal treatment is used to inject and activate the dopants in the Si substrate [2]. Integration with advanced lithographic technique could provide the possibility to control the lateral distribution of the dopants over the substrate at the nanoscale. Periodic distributions of dopants could be used to realize artificial crystal lattices [3] or, taking advantage of the non-uniform dopant distribution, novel devices for non-conventional computational tasks [4]. In this work P terminated PS homopolymers are combined with self-assembled block copolymer (BCP) thin films of polystyrene-b-polymethylmethacrylate (PS-b-PMMA) to demonstrate the capability to modulate P distribution over the substrate at the nanoscale. Upon deposition and grafting of the P terminated molecules over the substrate, a PS-b-PMMA BCP thin film is deposited by spin-coating on top of the sample and annealed at high temperature (250°C) to promote a phase separation and create an array of out of plane hexagonally packed PMMA cylinders with diameter of 25 nm inside a PS matrix. After the selective removal of the PMMA cylinders, a 5 nm thick layer of SiO2 is evaporated to create a protective capping on top of the exposed areas. Finally, the remaining PS nanostructure and the non-protected P terminated moieties are removed using piranha solution, resulting in an array of SiO2 disks on top of nanometer wide areas with high concentration of P. The effective amount of P over the surface is evaluated by means of TOF-SIMS and XPS analysis. Upon injection of P atoms into the underlying Si substrate, the distribution of active dopants is evaluated via sheet resistance and Hall effect measurements to study the effect of the periodic modulation of P on charge transport in the Si substrate. [1] M. Perego et al., ACS Nano, vol. 12, no. 1, pp. 178–186, 2018 [2] M. Perego et al., J. Mater. Chem. C, vol. 8, no. 30, pp. 10229–10237, 2020 [3] S. Yue et al., Phys. Rev. B, vol. 102, no. 20, pp. 1–5, 2020 [4] T. Chen et al., Nature, vol. 577, no. 7790, pp. 341–345, 2020

Resume : Group IV-V based semiconductor alloys have recently gained a renewed interest due to their lamellar structure. This property may open the route toward novel 2D group IV-V materials, which are expected to exhibit original electronic and optoelectronic properties. In the case of 2D-SiP, an indirect to direct bandgap transition has been predicted when moving from the bulk to the corresponding 2D material. While some theoretical works are available on 2D-SiP, there is still no report concerning the synthesis of 2D-SiP by mechanical exfoliation of SiP thin films. In this work, we investigate Si:P thin films obtained by co-evaporation in ultra-high vacuum. The films were prepared by co-evaporation of Si from an e-beam gun and P from a GaP decomposition source. The microstructural properties were investigated by energy filtered transmission electron microscopy (EFTEM), scanning transmission electron microscopy (STEM), energy dispersive and electron energy loss spectroscopies (EDS and EELS). The thermal crystallization of the films was followed by Raman spectroscopy. When considering Si:P thin films containing 40 at. % of P, we show that annealing at temperatures larger than 950°C leads to the formation of crystalline phases. Density functional theory calculations of the vibrational modes allow us to identify unambiguously the formation of SiP in our films. Both EDS as well as EELS allow us to identify a plasmon signature of the SiP phase. EFTEM characterizations reveal the coexistence of both Si and SiP areas in the films having sizes of a few microns. High resolution transmission electron microscopy imaging gives a clear evidence of the lamellar structure. Finally, EELS measurements allow us to achieve a spatially resolved chemical mapping for both Si and P atoms, which is in good agreement with the expected atomic structure for orthorhombic SiP. Our results are an important first step on the way to obtain 2D-SiP, a promising new material for which a direct bandgap has been predicted.

Resume : The appearance of localized surface plasmon resonance in highly doped Si nanocrystals (NCs) has opened a new field of applications for Si [1]. However, doping nano-Si remains a challenge due to self-purification effects [2]. If most of the highly doped Si-NCs are elaborated by bottom up processes [1], new routes involving top down approaches, as low energy electron lithography of heavily doped ultra-thin SOI wafers, can be appealing. In this case, a prerequisite step consists in the optimization of the top Si layer doping process. In this work, a thorough study of the heavy doping of thin Si films is described. UV nanosecond laser annealing (UV-NLA) is used to achieve an efficient dopant activation [3]. Ultra-thin SOI wafers with 23 nm-thick Si top layers have been implanted with phosphorus at 4 keV to different high doses and the NLA conditions have been optimized by numerical simulations [4]. The recrystallisation processes and P redistribution in the Si layer have been investigated as a function of the laser energy density by STEM-HAADF/EDX. Active dopant concentrations as high as 3 at. % have been measured by Hall effect and deduced from FTIR measurements coupled with Drude model based calculations [5]. Pile-up of P atoms at the surface has been observed together with a complete crystallization and a decrease of sheet resistance for optimized LTA conditions. [1] D. J. Rowe et al. Nano Lett. 13, 1317 (2013) [2] I. Marri et al. Prog. Surf. Sci. 92, 375 (2017) [3] K. Huet et al. MSSP 62, 92 (2017) [4] A.S. Royet et al. SISPAD (2019) [5] J.-M. Poumirol et al. ACS Photonics 8, 1393 (2021)

Resume : The appearance of localized surface plasmon resonance (LSPR) in highly doped Si nanostructures opens a new field of applications, with Si-based plasmonic tunable over a wide infrared range [1]. We present the experimental realization of ordered arrays of phosphorus hyper-doped silicon nanodisks, which exhibit a LSPR. This top-down approach consists at optimizing the doping of thin Silicon On Insulator (SOI) layers, by means of Laser Thermal Annealing, in which dense hexagonal arrays of nanometer size disks are produced by low energy electron beam lithography and reactive ion etching. Active dopant concentration in the bulk SOI as high as 3 at. % have been deduced from Fourier Transform Infra-Red (FTIR) spectroscopy in good agreement with Hall measurements. Intense mid to near-IR LSPR have been measured in FTIR on the doped nanodisks metasurfaces. The plasmon is widely tunable in a spectral window between 2 and 5 μm by simply adjusting the free carrier concentration between 1020 and 1021 cm−3 [2]. Our numerical simulations performed with the Green Dyadic Method (GDM) [3] show an excellent agreement with the experimental data and provide physical insights on the impact of the nanostructure shape as well as of near-field effects on the optical properties of the metasurface. Our results open highly promising perspectives for integrated all-silicon-based plasmonic devices for chemical or biological sensing or for thermal imaging. [1] D. J. Rowe et al. Nano Lett. 13, 1317 (2013). [2] J. M. Poumirol et al. ACS Photonics 8, 5, 1393-1399 (2021) [3] C. Majorel et al., Optics Communications 453, 124336 (2019).

Resume : Rare-earth (RE) doping of silicon oxide matrix [1-2] have attracted a lot of attention for the development of new photonics applications [3] and particularly Erbium because of its emission at 1,54 micrometer used in optical fiber. Optical properties of RE-doped Si-based matrix are strongly correlated with the nanostructure [4]. In order to overcome the low solubility of RE in silicon oxide matrix, the control of growth of Erbium silicates phases, which evidenced an intense luminescence [5-6], can be a promising approach. In present work, we have studied the relationship between high doping level of Er in silicon oxide matrix, the atomic scale location of Er atoms, the matrix phases chemistry and luminescence properties on samples with different Er contents and under different annealing processes. These experiments have been performed using photo- and cathodo-luminescence and atom probe tomography. We observe that in both case a similar nanostructure composed of an interconnected erbium silicates and silica phases at the nanoscale. The influence of the annealing process and the Er concentration will be discussed in regard of nanostucturation of the sample and optical properties. [1] A. Kenyon et al. Semiconductor Science and Technology, 20 (2005) 65 [2] D. Debajyoti et al. Phys. Chem. Chemical Physics,17 (2015) 5063 [3] N. Daldosso et al. Nanosilicon (2008) 314 [4] M. Fujii et al. J. Appl. Phys, 84 (1998) 4525 [5] G. Beainy et al. J. Alloys and Compounds, 755 (2018) 55 [6] R. Lo Savio et al. Appl. Phys. Let., 93 (2008) 021919

Resume : Performing effective doping of silicon nanocrystals (Si-ncs) embedded in SiO2 became a relevant subject in order to develop new plasmonic devices. In semiconductors, a perfect control of the charge density allows to tune the spectral position of the Localized Surface Plasmon Resonance. It has been shown that, depending of the elaboration conditions and their environments, P or B doped Si-ncs can exhibit a plasmon resonance. However, in low dimensional systems, the position of the impurity (in the core of Si-ncs, at the Si/SiO2 interface or in the surrounding matrix) can strongly affect these properties. Therefore a precise control of the location of impurities is necessary. In this work, P and B doped Si-ncs embedded in SiO2, elaborated by ion implantation or evaporation, have been investigated using Atom Probe Tomography. This technic allowed us to perform 3D mapping at the atomic scale to investigate the precise location of impurities and the Si clustering characteristics. We evidenced a clear difference on the location of impurities in Si-ncs. On one hand, P atoms are efficiently introduced in the core of every single Si-ncs allowing a high doping of these Si-ncs. On the other hand, B atoms remain in majority in the matrix, at the Si-nc/SiO2 interfaces or in shells surrounding Si-ncs. Finally, photoluminescence measurements highlight that in P as in B doped Si-ncs, these locations of impurities lead to a quenching of the Si-ncs luminescence.

Resume : As an emerging new class of plasmonic nanomaterials, heavily doped semiconductor nanocrystals (NCs) that possess infra-red Localized Surface Plasmon Resonance (LSPR) tunable with the doping concentration, have recently received great attention [1]. Silicon has been chosen for its compatibility with the CMOS technology. However, doped Si-NCs suffer from oxidation and surface modification, which may negatively impact their plasmonic properties [2]. For this reason, the Si nanostructures fabricated in this work are embedded in an insulating matrix (SiO2) that preserves the NCs from aging. In this work, highly phosphorus (P) doped small Si nanocrystals (3 nm) have been fabricated by sequential low energy ion implantation of Si and P, followed by Rapid Thermal Annealing (RTA). The impact on the P doped Si-NCs formation and optical properties of separating (or not) the NC nucleation from the dopant activation, as well as their thermal budget, have been investigated. The structural characterization by Transmission Electron Microscopy indicates that after P doping and further annealing, the Si-NCs remain crystalline with no effect of the P implant on the NCs average size. STEM-Energy Dispersive Spectroscopy and Atom Probe Tomography both evidence that P atoms (up to 4.2%) are efficiently introduced inside the Si-NCs. Photoluminescence (PL) spectroscopy shows a decrease of the intensity of the PL peak characteristics of Si-NCs after P doping that could be ascribed to Auger recombination, suggesting a partial activation of P inside the NCs [3]. Finally, FTIR measurements evidence for the first time the generation of IR LSPR from the P doped Si-NCs embedded in silica after a specific passivation of Si-NCs surface defects by forming gas annealing. [1] Luther J M, Jain P K, Ewers T, et al. Nature materials, 2011, 10(5): 361-366. [2] Kramer N J, Schramke K S, Kortshagen U R. Nano letters, 2015, 15(8): 5597-5603. [3] Pi X D, Gresback R, Liptak R W, et al. Applied Physics Letters, 2008, 92(12): 123102.

Resume : Ge/Si heterostructures with quantum dots (QDs) are considered as one of the most promising systems for creating silicon-based light-emitting devices. For practical applications the precise positioning of QDs is very important. In this work, we present experimental and simulation results on the self-organization of spatially ordered Ge(Si) QDs during heteroepitaxial growth on the pit-patterned SOI (silicon-on-insulator) substrates. The positions of pits were arranged to the square and hexagonal lattices with a varying spacing. It was shown that the location of GeSi QDs subsequently grown on the pit-patterned Si substrates depends on spacing for the both lattice types. In the case of the small spacing GeSi QDs are located mainly inside the pits, while for the larger inter-pit distance the groups of GeSi QDs at the pit periphery is also observed. The effect of QDs growth, first inside the pits, then at their periphery was reproduced by Monte Carlo simulations of Ge heteroepitaxial growth on the pit-patterned Si substrates. We also studied the photoluminescent (PL) properties of structures with GeSi QDs arranged around the pits on SOI substrate. It was found that, at certain parameters of an ordered array of pits (the period of the location of the pits, the pit shape, and depth), a significant increase of the QD luminescence intensity occurs. The array of pits plays the role of a photonic crystal (PhC), which is confirmed by the appearance of narrow peaks in the PL spectra, which can be associated to the interaction of QD emission with the PhC modes. This work is funded by the RSF grant # 21-72-20184.

Resume : GeSi is one of the most studied semiconductor alloy, with applications in microelectronics, optoelectronics and integrated photonics benefiting from tuning electrical and optical properties by varying the nanocrystals (NCs) size, composition and density. GeSi NCs boost the efficiency of light emission and band-edge absorption in GeSi large crystals by quantum confinement. A versatile technique is to embed Ge-rich GeSi NCs (with Ge content from 50% to 100%) in oxides, and this we achieve by magnetron sputtering for layers deposition. GeSi NCs formation is achieved eirher on heated substrates during deposition or by rapid thermal annealing after the deposition process [1,2]. We obtained photodetectors with Ge NCs in SiO2 with high responsivity of 2.42 A/W and 445% quantum efficiency, and 1325 nm cut-off wavelength. We also fabricated sensors with GeSi NCs embedded in SiO2 with significantly improved parameters, i.e. cutoff wavelength that is significantly extended to 1630 nm in SWIR and higher photoresponsivity of 9.35 A/W at 100 K, and even 1345 nm sensitivity limit and 5.23 A/W responsivity at room temperature. We employ DFT for finding bandgap diameter dependence of GeSi NCs for different Ge contents and bigger diameters, these being useful for design and characterization of GeSi NCs-based optical sensors [3]. These results prove the great potential of GeSi NCs-based sensors and photodetectors to be used in discrete and integrated devices. We have developed a sensor application based on the high VIS-SWIR photoresponsive GeSi NCs films, that discriminates between different slippery road conditions, in the frame of M-Era.Net project PhotoNanoP awarded as ?Success Story? [4]. [1] I Stavarache, C Logofatu, MT Sultan, A Manolescu, HG Svavarsson, VS Teodorescu, ML Ciurea, Sci Rep 2020, 10, 3252 [2] I Stavarache, VS Teodorescu, P Prepelita, C Logofatu, ML Ciurea, Sci Rep 2019, 9, 10286 [3] O Cojocaru, AM Lepadatu, GA Nemnes, T Stoica, ML Ciurea, Sci Rep 2021, accepted [4] C Palade, I Stavarache, T Stoica, ML Ciurea, Sensors 2020, 20, 6395

Resume : In this report, we discuss the results of experimental studies carried out for two-dimensional photonic crystals realized on Si structures with the self-assembled Ge(Si) nanoislands. These structures seems to be promising for realization of an efficient light-emitting source on Si chip. Si structures with the self-assembled Ge(Si) nanoislands are fully compatible with CMOS technology, could be easily fabricated and belong the emissivity within practically important wavelength range of 1.2–1.6 µm. However, their emission efficiency remains insufficient for device applications. In this report, we will show that this situation can be significantly improved by incorporating Ge(Si) nanoislands into photonic crystals. Making use the interaction phenomena of an active media with the photonic crystal modes, the emissivity of these structures can be increased by more than an order of magnitude. To integrate Ge(Si) nanoislands into photonic crystals, two approaches were considered, which differ by the ordering procedure of Ge(Si) nanoislands inside the photonic crystal. In the first one, Ge(Si) nanoislands were ordered during the growth on a pre-patterned Si substrate, and photonic crystals were formed on the structures with the already ordered nanoislands. In the second one, photonic crystals themselves served as templates for the ordered growth of Ge(Si) nanoislands [1,2]. In both cases, the strong, by more than an order of magnitude, increase of Ge(Si) nanoislands luminescence intensity of has been observed, though for the distinct ordering and photonic crystal parameters. The luminescence features observed in these structures are discussed in terms of the nanoislands – photonic crystal modes interaction phenomena. The specificity of modes involved in the luminescence response of these structures was analyzed by means of the micro-photoluminescence method in directional diagram geometry. This work is funded by the RSF grant # 21-72-20184. [1] Zh.V. Smagina, V.A. Zinovyev, E.E. Rodyakina et al., Semiconductors, 53(10), 1329 (2019). [2] A.V. Novikov, Zh.V. Smagina, M.V. Stepikhova et al., Nanomaterials 11, 909, (2021).

Resume : Colloidal crystals (CCs) realized by self-assembled polymer nanoparticles are volumetric and low-effort materials that found applications in surface coatings or photonics and phononics for light and hypersound manipulation, respectively. The mechanical properties of CCs result from the elasticity of the nanoparticles as well as interfacial forces between thereof. Typically, self-assembled nanoparticles are weakly bonded. Therefore, the fragility of polymer CCs remains a critical issue as it may result in malfunctioning of the devices and the releasing of micro/nano contaminants into the environment. To date, several approaches have been proposed to make polymer CCs mechanically robust: plasma and chemical assisted treatments, direct UV irradiation, and thermal treatment just below the glass transition temperature. This work discusses uniform mechanical reinforcement and tunability of polystyrene (PS) CCs employing supercritical fluids. This method, termed “cold soldering”, allows structural strengthening at temperatures well below the glass transition, which is especially important for thermosensitive systems. Cold soldering combines two relevant effects: plasticization of particles surface and compressive hydrostatic pressure. It results in permanent physical contact between the nanoparticles and maintains the periodic arrangement of the colloidal crystal. To monitor in-situ the mechanical vibrations of the crystal, we employed Brillouin light scattering. Using this non-destructive, contactless technique, we determined preferential pressure, particle size, temperature, and time range for soldering. References: [1] V. Babacic et al., J. Colloid Interface Sci., 579, 786 (2020) [2] B. Graczykowski et al., Nano Lett. 20, 1883−1889, (2020) Acknowledgments: The work was supported by the Polish National Science Centre (UMO-2018/31/D/ST3/03882) and Foundation for Polish Science (POIR.04.04.00-00-5D1B/18).

Resume : The use of nanostructured electrodes represents an alternative for improving the performances of opto-electronic devices because can favor both the manipulation of light through photonic/plasmonic effects and the charge carrier transport and collection through the modification of the electric field and increase in the collection surface of the electrodes. On the other hand, the limitation in the charge carrier injection and transport induced by the reduced diffusion length of exciton and reduced interfacial contact area between donor and acceptor in the classical bi-layer organic heterostructure can be overpassed using as active layer blends of donor and acceptor materials as bulk heterojunctions (BHJs). This paper presents a comparative study on the properties of organic heterostructures with BHJ active layer made of arylenvinylene based polymer with carbazol substituted unit in 2,7 and 3,6 positions as donor and fullerene derivative (C61) or non-fullerene (perylene diimide) as acceptor mixed in the ratio (1:2), deposited by Matrix Assisted Pulsed Laser Evaporation between Al (flat and nanopatterned) and ITO electrodes. The 2D periodic array of cylindrical pillars with a periodicity of 1.1 m and diameter of 400 nm realized with UV Nanoimprint Lithography was covered by the Al layer showing an inflorescence-like morphology. The nano-patterning of the Al electrode is preserved by the blend layer, independently of acceptor type, but the geometry of nano-patterning is slightly modified. The BHJ layers deposited on both flat and nanostructured Al have been characterized by spectroscopic (Reflectance, PL) and microscopic (AFM) methods and the effect of nano-patterning and type of acceptor on the optical and electrical properties has been investigated. The high roughness associated with the preservation of the nano-patterning and the light trapping by multiple scattering of the radiation inside the nanostructures led to lower reflectance of the layers deposited on nanostructured Al. A decrease in the emission intensity has been revealed by the nanostructuring of the Al layer for the heterostructures prepared with non-fullerene acceptor and longer conjugation length polymer (carbazol unit substituted in positions 3,6) donor at excitation both with UV and Vis radiation. The lower emission of the layer containing C61 compared to the layer containing perylene diimide is associated with the quenching of the luminescence. I-V characteristics in dark have revealed an injector contact behavior for all heterostructures Al/BHJ layer/ITO. The nano-patterning of Al electrode caused an increase in current for the heterostructures made both with non-fullerene and fullerene acceptor. The electrical behavior of the herostructures with BHJ layer containing perylene diimide is affected by the donor polymer conjugation length, the best effect of nano-patterning being obtained with a donor from the arylenevinylene based polymer characterized by a lower conjugation

Resume : Molecular layers at the surface of nanoparticles are of central importance both for basic and applied research. They determine how they can be process and how they interact with their environment, let it be molecules, other particles or even living matter. In the presentation it is shown how microspectroscopy can be utilised to follow ligand exchange processes by monitoring the chemical interface damping associated plasmon resonance linewidth changes of individual gold nanorods. It is shown, that even for small thiol molecules, the charged nature of the ligands has a profound effect on the outcome of the ligand exchange. By careful control of the thiol molecules, tip-selectively surface modified gold nanorods can be prepared. The in in-situ microscopy approach (the particles are investigated in their native, liquid environment) also offers the possibility to detect the assembly of these individual nanoparticles. By controlling the colloidal interaction of patchy particles’, the targeted preparation of certain nanoparticle arrangements becomes possible, as well as eventual structural rearrangements of the assemblies upon drying can be verified. Acknowledgement: National Research, Development and Innovation Office – NKFIH KH129578, FK128327 Key references: (1) Szekrényes, D. P.; Kovács, D.; Zolnai, Z.; Deák, A. Chemical Interface Damping as an Indicator for Hexadecyltrimethylammonium Bromide Replacement by Short-Chain Thiols on Gold Nanorods. J. Phys. Chem. C 2020, 124 (36), 19736–19742. https://doi.org/10.1021/acs.jpcc.0c04629. (2) Szekrényes, D. P.; Pothorszky, S.; Zámbó, D.; Deák, A. Detecting Spatial Rearrangement of Individual Gold Nanoparticle Heterodimers. Phys. Chem. Chem. Phys. 2019, 21 (19), 10146–10151. https://doi.org/10.1039/C9CP01541H. (3) Pothorszky, Sz.; Zámbó, D.; Deák, T.; Deák, A. Assembling Patchy Nanorods with Spheres: Limitations Imposed by Colloidal Interactions. Nanoscale 2016, 8 (6), 3523–3529. https://doi.org/10.1039/C5NR08014B.scale 2016, 8 (6), 3523–3529. https://doi.org/10.1039/C5NR08014B.

Resume : The aim of our research study was to implement a microfluidic platform for the development of amino- and carboxyl-functionalized iron oxide nanoparticles. Specifically, the microfluidic lab-on-chip device which has demonstrated to allow for the modulation of nanoparticle size, shape, crystallinity, and surface charge was further used to investigate its efficiency in controlling nanoparticle functionalization. The lab-on-chip device was assembled by fixing three poly(methyl methacrylate) plates of the same size, using 20 M4 screws (0.5 mm pitch, 4 mm diameter) and tightened at 1.5–2 Nm. The polymeric chips comprising a top layer (with inlets for sample injection and screw orifices for binding), a middle chip (with the cross-junction channel and screw orifices), and a bottom chip (with an outlet and screw orifices) were constructed through a laser cutting machine. The solution containing Fe(II) and Fe(III) precursors and the -NH2 and -COOH functionalization agents at different concentrations were injected through the central inlet. The solution of NaOH 1M used as a precipitating agent was injected through the side channels at 150 mL/h. The dispersions containing the functionalized iron oxide nanoparticles were dripped from the outlet, washed, and dried for 48 h at 40°C. After the synthesis process, the morphology, structure, composition, and functionality of the so-obtained functionalized nanoparticles were determined through scanning electron microscopy and transmission electron microscopy, selected area electron diffraction, X-ray diffraction, energy-dispersive X-ray spectroscopy, Fourier-Transform infrared spectroscopy, and dynamic light scattering. Furthermore, the thermogravimetric analysis was used in order to establish the functionalization degree of the nanoparticles. Results proved that the nanoparticles consisted of a single mineral phase, namely iron oxide, and a dimensional uniformity with sizes lower than 10 nm and uniform spherical shapes were obtained in all nanoparticle samples. Moreover, the thermogravimetric results proved a concentration-dependent functionalization degree for both amino- and carboxyl-functionalized iron oxide nanoparticles. In this manner, we can conclude that the microfluidic lab-on-chip device represents a promising tool that allows for the control of the amino- and carboxyl-functionalization process. Hence, the lab-on-chip device could be further used in nanomaterial-based pharmacological applications, as it permits the modulation of the pharmacokinetics and pharmacodynamics of the envisaged drug delivery systems.

Resume : Nanoscopic sharp tips have become a crucial component and workhorse for carrying out scanning probe microscopy (SPM) measurements with nanometer precision and resolution. A major limitation of common SPM analysis since its invention in the 1980ies has been the need to frequently replace worn-out tips. This manual tip replacement is not only time-consuming (~10 min/tip), costly (20-100 Euro/tip) and cumbersome but it represents also an unwanted interruption of the scanning experiment and is a major roadblock for SPM to tackle new analysis challenges. Therefore, we developed so-called reverse tip sample (RTS) SPM whereby the sample to be measured is fixed to the end of a cantilever beam and the scanning tip becomes part of a tip array chip. In this way, tips can be exchanged quasi on the fly without tip disengagement from the sample surface and thousands of tips are available at the user’s direct disposal. To fully exploit the advantages of the RTS SPM approach, we developed in this work tapered nanoscopic silicon tip structures (~1micron in height) and placed them in the center of silicon pedestals (~5 microns in diameter and ~10 microns in height). The innovative feature of our dry-etch based process is the self-patterning and -alignment of the silicon nano-tip. The fabricated Si tip chips have been used in RTS SPM measurements in contact and non-contact mode whereby measuring with 9 different tips (classical SPM is limited to a single tip only) on the same surface area which strongly improves the overall data statistics and variability. The silicon tips are ultra-sharp (2 nm) and have been evaluated for measurements on nanoparticle coated surfaces and bio structures (DNA). Our presentation explains our self-patterning and -alignment approach in detail, demonstrates fabricated silicon tip chips and highlights the high potential of RTS SPM for enabling new SPM measurements.

Resume : The nature of elastic waves propagating in a studied specimen depends not only on the material itself but also on its size and shape, especially in nanostructured samples. Periodic structures in nanoscale present many possible applications, such as in transducers of electromagnetic waves into elastic ones at GHz frequencies. As an example, gold linear gratings can be used in such an application. It is crucial to fully understand elastic properties of such structures and the propagation of waves both along and across the stripes prior to using them in a more complex system. Here, we present results of Brillouin light scattering (BLS) experiments performed on gold linear gratings with various periods of the order of a few hundreds of nanometers deposited on silicon wafers. BLS on such non-transparent samples allows characterization of surface acoustic waves, thus those mostly affected by the gold gratings. Obtained phonon dispersion curves exhibit multiple branches and additional zone folding due to the periodicity of the grating. The origin and characteristics of the branches will be discussed with the help of finite element method simulations. Transducing properties of gold gratings can be used in a unique method called pump-BLS, in which pulsed near-IR laser is used to induce elastic waves in the sample, while continuous-wave laser is used for probing using BLS spectroscopy around the gold grating to map wave propagation. Preliminary results from this method will be provided. This work was funded by NCN project No. UMO-2018/31/D/ST3/03882.

Resume : Porous anodized aluminium oxide (PAAO) is a spontaneously periodically ordered material with pores fabricated using electrochemical methods. To obtain a better uniformity of PAAO, the anodization is carried out in two steps: first anodization is longer, while second anodization depends on the desired thickness of the final structure. The PAAO from first anodization must be etched in, e.g., chromic acid. In this work, aluminium substrate was anodized in oxalic acid. Anodization voltage was 40 V. The duration of first anodization was 1 hour. During the process, every 2 s reflection spectra were recorded using ThorLabs SLS201L/M light source, Ocean Optics USB4000 spectrometer, and Ocean Optics SpectraSuite software. Spectra analysis and fitting was carried out using Octave freeware and propagation and matching matrices formalism as described by Sophocles J. Orfanidis in “Electromagnetic Waves and Antennas”. Simplified PAAO structure for fitting was considered: aluminium oxide with pores on aluminium substrate in water medium. In 1 hour, PAAO thickness reached 3176 nm. From the linear part of thickness dependence on anodization time graph (starting from approximately 250 s), PAAO growth rate was found to be around 0.9 nm/s. Knowing this rate helps to predict the required duration for second anodization. Acknowledgements: This research is supported by European Regional Development Fund postdoctoral project “Patterned hybrid multilayer films for optical sensors” (No. 1.1.1.2/VIAA/4/20/615).

Resume : The rational design of novel self-assembled nanomaterials based on peptides remains a great challenge in modern chemistry. We have been developing a hierarchical approach for the construction of nanofibrils based on alpha,beta-peptide foldamers. The methodology for the rational construction of helix-containing nanofibers includes the modification of coiled-coil structure outer positions with helix-promoting trans-(1S,2S)-2-aminocyclopentanecarboxylic acid (trans-ACPC) residue. The incorporation of trans-ACPC residue led to its increased conformational stability of obtained alpha,beta-peptides, which was established consistently by the results of CD, NMR and FTIR spectroscopy. The designed oligomerization state in the solution of the studied peptides was confirmed using AUC. Moreover, the cyclopentane side chain allowed additional interactions between coiled-coil-like structures to direct the self-assembly process towards the formation of well-defined nanofibrils, as observed using AFM and TEM techniques. We consider that the presented methodology will constitute a significant step towards a better understanding of beta-amino acid-containing peptide properties and will provide a basis for future discoveries of higher-order structures of self-assembling peptides.

Resume : Liquid suspensions comprising mixtures of spherical and cylindrical nanoparticles are complex fluids that may modify the phase diagram of each of the components forming hybrid materials with new functionalities and are commonly used in various applications. The ternary rod-sphere-solvent systems are expected to exhibit isotropic-nematic liquid-liquid phase separation with marked partitioning of the rods and spheres between the isotropic and nematic phase, where the spheres are almost totally excluded from the nematic phase thus enriched by the rods. Motivated by this rationale, we investigated the co-assembly of Cellulose Nanocrystals, CNCs, that self-assembles into a chiral nematic liquid crystalline phase in aqueous phases and an amphiphilic block copolymer Poly(ethylene oxide)-poly(propylene oxide)-poly(ethyleneoxide) PEO100-PPO70-PEO100 F127 Pluronic (BASF) that form core-shell micelles above its critical micellization concentration, CMC at room temperature, and. The combined system was characterized via several methods; structural characterization via small angle x-ray scattering (SAXS)and cryo-TEM, optical properties using polarized light microscopy (POM), surface properties via zeta potential and surface tension measurements. Our results indicate a very different behavior where hybrid liquid crystalline phase emerge from the co-assembly of F127 micelles and the suspended CNCs. The polymeric micelles are observed to modulate the interaction among the CNCs in the emergent phases: weak modulation is observed in CNCs-F127 mixtures of up to 10% (w/v) F127, where the mixed phases preserve the nematic order of the native CNCs phase, but the dimensions of the individual nanoparticles and the interparticle distance are modified due to adsorption of the F127 micelles onto the CNCs. Strong modulation and modification of the nematic phase is observed at higher F127 concentrations where competing interactions among the free micelles and the CNCs-micelle hybrid shape the nanostructure and length-scale of the emergent mesophase. Improved understanding of the assembly and phase behavior of multi-component systems comprising functional nanomaterials is expected to be beneficial for the development of new hybrid materials.

Resume : The role of nanotechnology in developing nanoparticle-based biosensors to improve the sensitivity and specificity of target detection is highly considerable. Among different nanomaterials, gold nanoparticles allow great platform for construction of biosensors owing to their novel and distinct characteristics which provide them with an edge over other nanoparticles. Recently, gold nanoparticles have been widely used to improve the analytical performance of the biosensors due to their unique optical and electrochemical properties, ease of synthesis, stability, and potential to conjugate with biomolecules. In this regard, we synthesized core/shell goldnanostars with no defects and dislocations with the building unites of about 10 to 60 nm. Due to the ease of controlling the shape and size of formed nanoparticles through the adaption of nucleation and grow conditions, seed-mediated growth method was applied to synthesize the nanostars. Sodium borohydride, Sodium citrate and Hexadecyl trimethylammonium bromide (CTAB) were employed as reducing, capping agent and stabilizer, respectively. Field Emission Scanning Electron Microscopy (FE-SEM) and Transmission Electron Microscopy (TEM) were employed to characterize the shape and size of the nanoparticles. To determine the average particles size and surface charge of the synthesized nanoparticles, DLS (dynamic light scattering) and ZP (zeta potential) measurements were performed. The result confirms the successful synthesis of star shaped gold nanoparticles with positive surface charge and great surface area which provide an excellent sensing platform for target molecule detection and its application in environmental monitoring and biomedical analysis.

Resume : Head and neck squamous cell carcinomas (HNSCC) are genetically complex, aggressive cancer type that is difficult to treat with convetional treatment methods such as surgical eradication, radiotherapy, and chemotherapy. Last years, there is an increase tendency for targeted therapies however effective results cannot be obtained for HNSCC. Nanotherapeutics have attracted attention in recent years to overcome the limitations of these traditional cancer treatment methods. Nanoparticle-based targeted therapy ensures that combination therapy for treating head and neck carcinoma cells, such as enhanced preferential tumor-killing efficiency and reduced toxicity to healthy cells. Various types of nanoparticles have been applied in the medical field to carry therapeutic agents, such as iron oxide nanoparticles, lipid-based nanoparticles, etc. Unlike other nanoparticles, cerium oxide or nanoceria promises to avoid the disadvantages of conventional treatment methods for HNSCC, as it acts as an antioxidant and radioprotective agent with cell selective properties for cancer application. The research, therefore, focused on the effects of two different syntheses of dextran-coated cerium oxide (nanoceria) nanoparticles on four HNSCC cell lines through analysis of their cytotoxicity and reactive oxygen species (ROS) scavenging properties. This study is supported by the International Centre for Genetic Engineering and Biotechnology (ICGEB) under CRP/TUR 18-03 project number.

Resume : Nanoparticle-based cancer treatments have become attractive recently as an alternative to conventional treatments for colon cancer such as chemotherapy, biological agents, alkylating agents, and antimetabolites. However, the major problem is the side effects that arise in distinguishing normal and cancerous cells and resulting from complications that produce systemic toxicity. Therefore, the application of nanoparticles in cancer treatment emerges as a method aiming for controlled drug delivery and minimizing side effects. Unlike other nanoparticles such as silver, zinc, polymeric and gold nanoparticles etc., used to treat colon cancer, nanoceria is one of the most promising nanoparticles due to its excellent catalytic activities, which is derived from rapid oxidation state between Ce4+ and Ce3+. The hypothesis regarding the action mechanism of nanoceria is that cancerous cells are predicted to be acidic and nanoceria can increase the oxidative stress of these acidic cells and apoptosis leading to the destruction of cancer cells. In this study, Nanoceria’s cytotoxicity along with reactive species (ROS) scavenging properties was observed in the presence of colon cancer cells at different pH (pH 6 and 7) values mimicking the tumor pH as well as the healthy cell pH environment with different doses and combinations in cell culture were determined. This study is funded by the International Centre for Genetic Engineering and Biotechnology (ICGEB) under CRP/TUR 18-03 project number.

Resume : Nanoparticles, with tremendous pharmacological potential, have been drawing attention in anticancer therapy. Nanoceria, a well-known redox catalyst, has a lot of promises as anti- or pro-oxidant therapeutics and radioprotective agents. Its redox modulatory and enzyme-like activities comes from surface cerium atoms’ ability, which can cycle in between Ce+3 and Ce+4. There are various studies to define nanoceria`s function through redox characteristics which are influenced by particle size, shape, surface chemistry and other factors such as coating agent, local pH and ligands. However, there is limited experimental data on nanoceria`s role in ligand/receptor recognition and in signaling pathways. Therefore, there is a need to understand the detailed function of nanoceria as a specific drug candidate for cancer therapy. In this study, we aimed to determine the role of dextran-coated nanoceria (DCNC) on apoptotic and EGFR-associated pathways through analyzing the gene expression profile specifically in various lung cancer cell lines and lung fibroblast. Firstly, the cytotoxic behavior and reactive oxygen species scavenging abilities of synthesized and well-characterized DCNC were investigated against several lung cancer cell lines and healthy fibroblasts after treatment with varied dosages. Last, the gene expression profiling was examined. This study was supported by International Centre for Genetic Engineering and Biotechnology (ICGEB) under CRP/TUR18-03 project number.

Resume : The self-assembly and phase behavior of cellulose nanocrystals (CNCs) in binary liquid mixtures of Ethylene-Glycol (EG): Water was investigated. CNCs are charged rigid-rod nanoparticles that exhibit first-order phase transition from isotropic suspension to chiral nematic (N*) liquid crystal (LC) phase above a critical volume fraction in aqueous suspensions. Our findings indicate that a small fraction of water delays the onset of colloidal jammed states previously reported in water-free organic solvents. Here the full phase diagram of CNCs evolves, including the N* phase, characterized by long-range orientational order and non-isotropic macroscopic properties. Furthermore, the effect of the solvent-mixture composition on the properties of the CNCs mesophases is found to be scale-dependent: The micron-size pitch of the N* phase decreases as the dielectric constant of the solvent mixture is reduced (higher EG content). Yet, the nanometric inter-particle spacing of the CNCs rods (measured using SAXS and cryo-TEM) is almost independent of the EG content. These observations may be rationalized by hypothesizing that vicinal water, adsorbed at the CNCs surface, prevent kinetic arrest, dictate the dielectric constant and thus the effective diameter of the rods (via the Debye length), while the dielectric constant of the liquid mixture dominate the pitch length (micron scale) and the optical properties. The findings indicate that the water content of EG: Water mixtures may be used for engineering colloidal inks where delayed kinetic arrest and jamming of the CNCs enable printing and casting of tunable, optically active thin films and coatings. Following these findings, the study was extended to the investigation of mixtures of nonionic surfactant, single-walled carbon nanotubes (SWNTs), and CNCs. The observations indicate that the 4-component system (SWNTs-CNCs-surfactant-water) organizes by forming a network of surfactant-dispersed SWNTs that co-exists with the CNCs mesophases, where the surfactant molecules mediate the interactions and lead to the formation of a hybrid. Indeed, dried samples show homogeneous distribution of the CNTs in the CNCs phases.

Resume : Materials science of carbon nanotubes (CNTs) lies at the intersection of various paradigms from fundamental to applied physics and chemistry. However, understanding the mechanism of CNTs formation through different concepts remains a considerable challenge. Currently, to be able to use CNTs for specific applications, the synthesis of CNTs with the desired diameter and chirality remains one of the most critical challenges for nanotube science. To face this challenge, the understanding of growth mechanisms of CNTs has to improve and complete, thereby developing highly selective synthesis methods. Previous studies suggest that the use of catalysis in carbon tube growth significantly enhances understanding of the very early stage of CNT nucleation and is a promising method for the selective synthesis of CNTs through the chirality control. A well-controlled synthesis of catalyst nanoparticles (composition, morphology, size) appears to be a mandatory condition for controlling the characteristics of the as-synthesized nanotubes. This study aims to complement the well-established ex-situ TEM observations of SWCNTs growth with Raman spectroscopic analysis and scanning electron microscopy (SEM) when Fe-Mo catalyst is used. The synthesis was carried out in a homemade hot filament chemical vapor deposition (HFCVD) reactor. This CVD system allows conducting studies on the influence of various parameters in synthesizing SWCNTs such as temperature, pressure, gas flow and catalyst. The unique feature of this system is the ability to reduce the reaction pressure to a maximum of 10-4mbar allowing studies of the SWCNTs synthesis at low pressure. As applied to different new and controlled bimetallic nanoalloy catalysts types, such as Fe-Mo catalyst, the emphasis is to understand the role played by the catalyst and put forward a growth mechanism essential to realized SWCNTs with specific and targeted chirality. In particular, we will discuss the role of the growth pressure on the final SWCNTs structure, In the view of experimental results, we observed a strong influence of Mo when it acts as a co-catalyst with Fe. The SWCNTs growth mechanism is “tip-mode”, in which the catalyst nanoparticles reside at the top of CNTs. Mo acts as a co-catalyst to improve the ability of small Fe catalyst nanoparticles to stay active among conditions of high carbon flux with CH4, thereby contributing to an increase in the number of synthesized SWCNTs. With 0.5 nm of Fe thickness, a sufficient amount of added - Mo could enhance the quality of SWCNTs and increase the number of SWCNTs. However, the effect of Mo gradually decreases when a large amount of Mo is used as a co-catalyst. This study will be a prototype for the in-situ study in the environmental transmission electron microscope (ETEM) implemented with a CVD gas source. Special thanks to the ANR’s funding for the project GIANT (number: ANR-18-CE09-0014)

Resume : The mechanical properties of hybrid organic-inorganic nanomaterials and nanostructure is central to their implementation in a wide range of applications and their synergic behavior can induce enhanced mechanical performance. In recent years, SIS has emerged as a promising new technique for fabricating hybrid materials with nanoscale precision. In SIS, inorganic materials are grown within polymers from vapor phase precursors. Several studies have demonstrated the potential of SIS to tune the mechanical properties of polymers. However, a full understanding of the relationship between the nanoscale structure and composition and the nanostructure mechanical behavior is still an ongoing effort. In this research, we study the mechanical response of pristine and hybrid nanopillars fabricated via SIS using a combined experimental and theoretical approach. Nanopillars were fabricated by e-beam lithography of poly(methyl methacrylate), followed by AlOx SIS using trimethylaluminum and H2O as precursors. The mechanical responses were studied with in-situ nanoindentation combined with scanning electron microscopy. We probed the pillars’ mechanical behavior as a function of AlOx loading and depth profile within the pillars. In addition, we developed a microscopic model which idealizes hybrid materials as multilayered structures considering their microstructure profile. The model showed good agreement with the measured mechanical performance.

Resume : In terms of pollutant gas detection (CO, NOx, etc) conducting polymers, in comparison with metal-oxides, present numerous advantages such as a room temperature operation, high sensitivity and short response time. Conductive polymers like polyallylamine or polypyrrole were deposited by Matrix assisted pulsed laser evaporation (MAPLE). The detection of pollutant gas (CO, NOx,) was determined. In order to enhance the electrical response, the polymers was mixed with carbon nanostructures (CNW, nano-horns, nanotube) and the pollutant response of such structure was compared with polymers. The properties of polymers thin layer and also of polymers/carbon nanostructures were analyzed by different technique: morphological and topography by SEM and AFM, the thickness of layers were calculated by SEM and spectro-ellipsometry. Acknowledgements: This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS/CCCDI – UEFISCDI, project number PN-III-P2-2.1-PED-2019-4734, within PNCDI III.

Resume : Air pollution harms the environment over the world and the human health is seriously affected by a toxic environment. The European Union (EU) identifies some pollutants with harmful effect on human health, such as: nitrogen oxides (NOx), carbon monoxide (CO), ozone, etc. In order to determine the presence of such pollutants we propose a new approach based on piezoelectric thin films deposited on mono-crystaline substrates covered by polymers. The piezoelectric layer was deposited by Pulsed laser deposition technique (PLD). The polymers used in detection of polluting gas were processed by Matrix assisted pulsed laser evaporation (MAPLE). The electrical properties of polymers/piezoelectric structure were analyzed in the GHz frequency regime. The morphological and topography of the piezoelectric and polymers layers were analyzed by AFM and SEM technique. The thickness of layers were calculated by SEM and spectro-ellipsometry. Acknowledgements: This work was supported by a grant of the Ministry of Research, Innovation and Digitization, CNCS/CCCDI – UEFISCDI, project number PN-III-P2-2.1-PED-2019-4734, within PNCDI III.

Resume : Optically-controlled microwave devices are one of the key technological components to achieve optical communication, it has been used in various optoelectronic application by providing high-data rate, frequency bandwidth and switching speed by controlling it optically. The objectives of this work thus include, the synthesis of up conversion nanomaterial capable to up-convert 1.5 micron to visible wavelength. Because efficient microwave devices controlled by 1.5-micron photons are highly demanded but technologically still difficult to achieve. In this work Er/Yb co-doped MoS2 and Er doped MoS2 powder has been synthesis via facile hydrothermal technique which shows up conversion at 1300nm and 1500nm also fabrication is economic, environmental friendly and less time consuming. By the use of up conversion nanosheets deposited directly onto Si substrate to achieve microwave photoconductive switches functional at  = 1.55 µm illumination. Due to the up-conversion energy transfer from the material, a significant increase of ON/OFF ratio was observed on the Er/Yb MoS2 and Er doped MoS2 on Si substrate device by comparison to the control device without up conversion material.

Resume : The total and partial densities of electronic states (DOS) of copper, silver and gold monolayer structures from 1 to 10 monolayers thick were calculated within the framework of the density functional theory. It was found that the tendencies in the formation of the DOS curve during the transformation from a monolayer to a bulk sample for copper and gold are of the same nature. The introduction of vacancies into the such monolayer leads to a shift in the main maximum and, in some cases, to a splitting of the features on the DOS curve, which brings the final shape of the density of states curve closer to that for thicker slabs. It is shown that the location of topological neighbors in the sample, the variability of atomic positions and the corresponding sets of bonds are the determining factor in the formation of the noble metal plates DOS curve. The largest contribution here is made mainly by d states. The symmetry of the monolayer plane, as well as the presence of packing defects and/or vacancies, significantly affects the electronic states of the sample and can act as a ?bulking? method of the DOS curve. Thermal deposition of Ag on the semiconductor Si (111) single crystal surface under ultrahigh vacuum conditions at the room temperature leads to the formation of several-layer 2D cluster formations, heating of which at several hundred degrees Celsius leads to their stretching into an atomically smooth coating of the surface. The formation of the "carpet" effect is described by the electron growth mechanism. The transformation of the boundaries of 2D monolayer silver clusters on the Si (111) 7x7 surface upon moderate annealing up to 350 ° ? leads to the appearance of topological inhomogeneities up to 0.04 nm deep, which are determined by the absence of complete relaxation of interatomic distances in the inter-cluster region.

Resume : Topological insulators (TI) are of particular interest in quantum computing, nanoelectronics, and spintronics [1,2] due to their unique physical properties. They are considered as key materials in the innovation of quantum devices thanks to their topologically protected surface states [3]. The Bismuth-Antimony alloy (Bi(1-x)Sb(x)), besides being the first reported 3D TI [4], has attracted much attention especially in spintronics applications due to its large conductivity [5,6] and its colossal spin Hall angle [7]. Nevertheless, its integration on a standard industrial substrate remains an industrial bottleneck. Herein, we successfully grow high quality BiSb thin films on GaAs(001) substrates despite the large mismatch and different crystalline matrices. We show the significant impact of the Sb composition not only on the electrical behaviours of BiSb but also on the orientation and size of BiSb grains. By optimising the growth conditions and controlling the Sb composition in the TI range, we demonstrate an epitaxial relationship between the BiSb layers and the substrate thanks to SEM, AFM, EBSD, HR-TEM and STM characterisations. Moreover, 80% of grains have the same orientation than the substrate. Finally, the electrical characterisations confirm the semiconductor behaviours of the BiSb bulk with the presence of metallic surface states detected at 77K. [1]: -Moore, J. E. The birth of topological insulators. Nature 464, 194?198 (2010). [2]: -Tang, S. & Dresselhaus, M. S. Electronic properties of nano-structured bismuth-antimony materials. J. Mater. Chem. C 2, 4710?4726 (2014). [3]: -Hasan, M. Z. & Kane, C. L. Colloquium: Topological insulators. Rev Mod Phys 82, 3045?3067 (2010).? [4]: -Kane, C. L. & Mele, E. J. $Z_2$ Topological Order and the Quantum Spin Hall Effect. Phys Rev Lett 95, 146802 (2005).? [5]: -Kozhemyakin, G. N. & Zayakin, S. A. Magnetoresistance in doped Bi0.85Sb0.15 single crystals. J. Appl. Phys. 122, 205102 (2017). [6]: -Qu, D.-X., Roberts, S. K. & Chapline, G. F. Observation of Huge Surface Hole Mobility in the Topological Insulator $\mathrmBi_0.91\mathrmSb_0.09$ (111). Phys Rev Lett 111, 176801 (2013). [7]: -Khang, N. H. D., Ueda, Y. & Hai, P. N. A conductive topological insulator with large spin Hall effect for ultralow power spin?orbit torque switching. Nat. Mater. 17, 808?813 (2018).

Resume : Transition metal dichalcogenide (TMD) quantum dots (QDs) often exhibit unique size-dependent properties owing to the quantum confinement effect. The challenges associated with TMDs are their aqueous solubility and their organic solvents-dependent synthesis methods. Herein, we report a green, one-pot hydrothermal-based synthesis of Tungsten Disulfide quantum dots (WS2 QDs). Polyethylene glycol (PEG) is utilized for the in-situ functionalization of WS2 QDs and acting as a stabilizing agent in an aqueous solution. The synthesized PEGylated WS2 QDs are 4-6 nm in size determined using HR-TEM. The QDs showed excellent dispersion in cultural media. The biocompatibility of QDs was evaluated using cellular toxicity on L929, Hemocompatibility, and ROS generation study. PEG_WS2 QDS has intrinsic blue fluorescence and Near Infrared absorption, which could be applied to image-guided photothermal therapy. This green and facile strategy will prompt the fabrication of an in-situ functionalization of various TMDs based nanomaterials.

Resume : Nowadays megajoules of thermal energy are wasted each second during industrial processes, transport, bioprocesses in our bodies, etc. since energy transformation processes are far from 100% efficiency. Consequently, the generate waste heat. One of the proposed solutions to increase the level of sustainability in daily life is the recovery of thermal energy by thermoelectric generators, which are based on the Seebeck phenomena. When subjected to a temperature gradient, waste heat can be changed into useful electrical energy. Nanocarbon materials like single/multi-walled carbon nanotubes, graphene and other nanocarbon materials revealed a particularly promising performance on this front [1,2]. However, the properties of nanocarbon still have ample room to obtain even higher thermoelectric performance. Hummers method was developed during the 60s of the XX century by William Hummers and Richard Ottoman,[3] and nowadays it is the most popular way to synthesize graphene oxide (GO).[4] Besides graphite, carbon nanotubes (CNTs) can be used as a raw material for production of an interesting type of GO. During this process, CNTs are transformed into a new 2D oxidized nanostructure called GO nanoribbons. Depending on the ratio of oxidation agent to CNTs or temperature, the reaction gives different products: intact CNTs (too small amount of oxidant), oxidized CNTs, GO nanoribbons (CNTs are unzipped by oxidation if the amount of oxidation agent is sufficient), or CO2 (when the amount of oxidant is excessive).[4] This research was focused on analyzing the influence of the parameters of the Hummers method on the properties of the obtained products of oxidation of large-diameter single-walled CNTs (SWCNTs). The impact of such conditions as a ratio of KMnO4/SWCNTs or reaction temperature/time on the microstructure and composition of the products of reaction was established. These were gauged by Raman spectroscopy, Scanning Electron Microscopy, and Transmission Electron Microscopy. Finally, macroscopic ensembles from the material were assembled to measure the electrical conductivity of the material by the four-probe method and for the selected samples Seebeck coefficient. The main factor determining the structure/properties of the product was found to be the employed ratio of the oxidant to the raw material i.e. KMnO4 to SWCNTs.[5] References: [1] N.T. Hung, et al., Thermoelectric properties of carbon nanotubes, Energies. 12 (2019) 4561. doi:10.3390/en12234561. [2] T. Li, et al., Thermoelectric properties and performance of flexible reduced graphene oxide films up to 3,000 K, Nat. Energy. 3 (2018) 148?156. doi:10.1038/s41560-018-0086-3. [3] W.S. Hummers and R.E. Offeman, Preparation of Graphitic Oxide, J. Am. Chem. Soc. 80 (1958) 1339?1339. doi:10.1021/ja01539a017. [4] A.M. Dimiev, et al. Revisiting the Mechanism of Oxidative Unzipping of Multiwall Carbon Nanotubes to Graphene Nanoribbons, ACS Nano. 12 (2018) 3985?3993. doi:10.1021/acsnano.8b01617. [5] G. Stando, S. Han, B. Kumanek, D. ?ukowiec, D. Janas (in preparation) Acknowledgments G.S. would like to thank the Ministry of Science and Higher Education of Poland (under Diamond Grant, grant agreement 0036/DIA/201948). G.S, B.K and D.J. would like to thank the National Centre for Research and Development, Poland (under the Leader program, grant agreement LIDER/0001/L-8/16/NCBR/2017).

Resume : Hematite (?-Fe2O3) is the most frequently investigated iron oxide since it is the most stable and common phase existing in nature. The surface structures of hematite are of immense interest in water purification, catalysis, geochemistry, and other technological applications. However, its properties strongly depend on the crystal structure, which depends on the way of their preparation. In this study, we examined the near-surface region of the single crystal of the ?-Fe2O3(0001) hematite by Transmission Electron Microscopy (TEM) for several samples which surface was prepared in ultra-high vacuum by sputtering, annealing, and low-pressure oxidation. There are two types of samples. The first one is where the surface is reduced into a magnetite (Fe3O4(111)) phase by Ar ion sputtering followed by annealing in a vacuum, denoted by R-phase. The second one is oxidized to a honeycomb superstructure by annealing in O2, denoted by H-phase, manifested by a Low-Energy Electron Diffraction (LEED) pattern. The deposited silver layer protects the sample surface layer from the subsequent lamella preparation for (Scanning) Transmission Electron Microscopy ((S)TEM). Despite the H-phase present on a range of samples, we see distinct near-surface layers. The phase identification of the intermediate layers is performed by Electron Energy Loss Spectroscopy (EELS) measurements.

Resume : In this studyr we have dealt with the influence of the substituent on the electronic structure of the hexatriene substituted by halogens F, Cl and Br. The DFT analysis of the geometric parameters (distances and angles) carried out on this type of molecules made it possible to show that the change of the substituent does not modify the geometry of these compounds. Mulliken's net charge analysis showed that the substitution of chlorine and bromine atoms gives a strong localization of negative charges on carbon atoms. The DFT and HF analysis of the dipole moment, of the polarizability and of the first hyperpolarizability allowed to show that the three molecules are good candidates for the nonlinear optical materials. The absorption spectra of these molecules are almost in the UV range. The 2-F, 1-Cl and 2-Br molecules are characterized by a hyperchromic effect. Keywords: Substitued Hexatriene; HF; DFT; absorption spectra; Polarizability

Resume : Sequential infiltration synthesis (SIS) has emerged in the past decade as a powerful technique for growth of inorganic materials within polymers through atomic layer deposition (ALD) chemistry. In SIS, ALD precursors diffuse into the polymer, leading to growth of nanoscale inorganic materials within the polymer volume. Here, I will present our recent research in the field of SIS. We shed light on the atomic growth of metal oxide clusters and particles within polymers using high-resolution transmission electron microscopy and x-ray absorption spectroscopy. We follow SIS growth from the nanoscale to the macroscale, expanding our understanding of SIS mechanism and the role of polymer chemistry and reversible polymer-precursor interactions on SIS growth. These insights are then applied in fabrication by design of homopolymer and block copolymer-templated 3D nanostructures, fibers, and membranes. We fabricate Al2O3-ZnO heterostructure nanorod arrays and core-shell nano-fibers, where simultaneous but spatially-controlled growth of the two metal oxides within the polymer templates is performed via control over the two precursors diffusion time. Block copolymer particles and films template porous metal oxide particles and membranes with uniporous pore size and controlled surface chemistry. These examples highlight the versatility and potential of SIS nanostructure fabrication by design capabilities.

Resume : Solvent evaporation annealing (SEA) is a simple method to enhance block copolymers' self-assembly. The basic concept of this method is to maintain polymer in a more plasticized state by extended solvent evaporation. It can be achieved by both chemical (addition of non-volatile solvents), and physical methods (lowering down the temperature, limiting evaporation surface). When the polymeric film remains in a swollen state for a sufficient time, the ordering progresses in and the grain sizes produced that way are significantly larger than in unprocessed samples. The simplicity of this method leaves plenty of room for further improvements, e.g., the single-step casting of a mixture of polymer and inorganic precursor that incorporates selectively into one of the blocks. It presents an alternative for Sequential Infiltration Synthesis or metallization by immersion in solutions of metal salts. However, the presence of an additional component may negatively influence the ordering kinetics of the block copolymer itself. In current studies, we investigate the kinetics of block copolymer self-assembly in the presence of the additional compound, i.e. metal complexes. We focus on high molecular weight block copolymers (above 100 kg/mol) consisting of polystyrene and polyvinyl pyridine blocks the latter prone to the complexation by a variety of metal precursors. We also run a series of experiments to determine where the Order-Disorder Transition occurs in the presence of another compound. All results were confirmed with image analysis of large-scale high-resolution SEM images. Presented results indicate, that there is a dependence between the quality of final morphology and evaporation rate during the process and precursor loading. Kinetic studies of SEA in the presence of metal precursor pave the way to a universal platform for the rapid and cost-effective production of large-scale inorganic metal and metal oxide nanostructures. The optimization of the process improves the final result and leaves a promising alternative to other methods that provide well-ordered isotropic morphologies.

Resume : Block copolymers (BCPs) are considered promising materials for various membrane applications ranging from ultra-filtration for water treatment to protein separation due to their ability to self-assemble into highly ordered structures with uniform pore size and high pore density. Typically, the pore?s size and surface interactions are controlled by the BCP chemistry. However, simultaneous control over both properties is difficult to achieve. In particular, controlling the size and functionality of the pores through the BCP chemistry is considered a major challenge. In this study, we aim to tailor the size and chemistry of BCP based ultrafiltration membranes by selectively growing metal oxides inside the pores. Poly (styrene-b-4-vinyl pyridine) (PS-b-P4VP) were used to create ultrafiltration membranes in a process combining self-assembly with non-solvent induced phase separation (SNIPS). This results in one integral but asymmetric membrane, with ordered pores at the top of the membrane and sponge-like mechanically robust support layer at the bottom of the membrane. Sequential infiltration synthesis (SIS), an atomic layer deposition based technique that enables selective growth of metal oxides inside the polar domains of BCP, was used to grow Al2O3 inside the P4VP domains of the BCP films. By incorporating metal oxides in the pores, the pore size can be reduced. By modifying the number of SIS cycles and/or the metal oxide we use, we can achieve control over the pore size while adding new functionality to the membrane, for example anti-fouling properties that ZnO exhibits. Structural characterization was performed by scanning electron microscopy (SEM) to probe the surface structure and analyze the resulting membrane pore size distribution. To confirm the penetration and incorporation of the metal oxide in the membranes, cross sectional SEM and transmission electron microscopy (TEM) was performed. By modifying the SIS process, control over pore size can be achieved. The control over pore size as well as surface chemistry, can allow for overall improved membrane performance.

Resume : Robust and efficient process for synthesis of various composition inorganic coatings with controlled nanoporosity and structure is highly desirable for design of efficient catalytic, purification, and detection systems. Recently, infiltration of a nanoporous polymer template with inorganic precursors using sequential infiltration synthesis (SIS) with inorganic vapor precursors followed by oxidative annealing was proposed as a new and efficient approach to create porous inorganic structures with tunable porosity and composition. The major limitations of the original water-based thermal SIS, though, are the thickness of the patterned structure being limited by vapor penetration depth of the precursors into the polymer template and the SIS material selection restricted by the availability of high vapor pressure precursors. Here, we propose a swelling-based modification to the SIS process that allows to overcome these limitations. We summarize the basics of the multi-step infiltration approach, the structure and properties of the resulting materials, and their functional potential for practical applications. We report ultra-high accessibility of the pores when porous films are prepared via the polymer swelling-assisted SIS. Using a quartz crystal microbalance (QCM) technique, we demonstrate increased solvent absorbing capabilities of highly porous ceramic films as a result of high interconnectivity of the pores in such structures. Our results show that the SIS can be been extended toward preparing conformal coatings, freestanding membranes, and powders consisting of metal or metal oxide nanoparticles embedded in a porous oxide matrix.

Resume : Sequential Infiltration Synthesis (SIS) process is a very promising process for the manufacturing of organic-inorganic hybrid materials from vapor phase. SIS involves the sequential exposure of the materials to alternating vapor phase organo-metallic precursor and a co-precursor, intercalating appropriate purging cycles of inert gas to remove unreacted molecules or reaction by-products. During the exposure time of precursors in static vacuum, the precursor diffuses into the sample and remains entrapped inside the material. Then the exposure to co-precursor leads to the formation of the desired hybrid materials. SIS is a very complex process that involves physical phenomena and chemical reactions of the precursors inside the polymer matrix. Presently, this process has been applied on several polymer materials incorporating different metal oxide to modify the initial polymer properties such as tensile strength, changing the permeability of membrane and improving conductivity of polymer. However a comprehensive picture of the effective processes taking place during SIS is still missing. This work aims to understand Al2O3 infiltration process in poly(butylene succinate) (PBS) thin films. PBS is a biodegradable polyester, that has excellent processability. Although its commercialisation is mainly devoted to biodegradable packaging, the use of PBS in the biomedical field has recently attracted considerable attention. Infiltration of Al2O3 into the PBS matrix could modify water and oxygen permeability of the polymer film, creating an effective barrier for oxidizing agents. In this research, PBS thin films of different thickness were prepared by spin-coating and infiltrated with Al2O3 at 70°C, varying the number of SIS cycles and TMA pulse time. Finally, plasma treatment was performed to remove the organic phase and to estimate the alumina mass uptake at different process conditions. We performed a systematic analysis of the morphology (SE, SEM and optical microscope) and composition (ToF-SIMS, XPS) of the processed samples. According to the collected data, PBS exhibits an excellent capability to entrap organo-metallic precursors inside the polymer matrix, leading to a very high amount of Al2O3 infiltrated into the polymer matrix at each cycle. In particular, we demonstrate that the amount of incorporated alumina depends on the specific processing conditions and on the initial thickness of PBS films. Accordingly, preliminary information about the diffusion of the TMA inside the polymer matrix has been obtained. In conclusion, we demonstrate for the first time, the possible formation of Al2O3-PBS hybrid materials by SIS process, providing information about the fundamental mechanism driving the infiltration process into this specific polymer.

Resume : Fabrication of the state-of-art miniaturized nanostructures present in modern electronics is mainly based on EUV lithography. This approach, however, has almost reached its physical limits and alternative fabrication schemes are sought e.g. by utilization of molecular self-assembly phenomena. Among several classes of molecules that self-assemble, block copolymers (BCPs) form diverse morphologies with desired dimensions matching those required by nanofabrication. Researchers still struggle to find a convenient and fast method for obtaining well-ordered BCP matrices in a controlled way. Frequently, the choice of the BCP ordering method is a matter of compromise between the complexity and the quality of the final morphology. For example, vapor annealing forms fingerprint morphologies at a relatively short time with small effort. On the contrary, more sophisticated methods such as grapho-, chemoepitaxy or photothermal annealing require the construction of more complex setups but eventually provide uniaxial and long-range ordering. Here, we present an approach, called Solvent Evaporation Annealing (SEA), which provides a beneficial combination of simplicity with a good degree of ordering at a reasonable cost. The process requires an addition of a low volatile compound to the traditional BCP casting solution containing a volatile solvent (e.g. toluene). Interestingly, prolongation of a usual coating step, defined by solvent evaporation duration, results in a formation of BCP film morphology with a domain size exceeding several micrometers that is hardly achievable for conventional thermal methods. Ordered BCP films are an intermediate stage for the fabrication of inorganic nanostructures. Further conversion utilizes the universal scheme of selective binding of metal precursor molecules to one of the blocks. Such methods as Sequential Infiltration Synthesis or Aqueous Metal Reduction require initially ordered BCP matrices, thus the conventional process consists of two separate steps. Here, we merged the ordering and conversion of a BCP template in a single step by adding a metallic precursor into the SEA solution. As a result, we successfully infused selectively one of the domains with metal precursors. The simplicity of this method is of great advantage – one requires only a properly composed BCP-salt solution and a coating device. So far, we have successfully obtained metal/metal oxide replicas for several transition metals. We characterized the morphology of patterned nanostructures with SEM as well as their chemical composition with spectroscopic analysis. Additional investigations of principles governing the process will undoubtedly make this approach more convenient in terms of its further widespread applications ranging from optical coatings, nanoelectronic structures to catalytic materials.

Resume : Atomic layer deposition (ALD) has emerged as an important technique for depositing high-quality thin films due to the self-limiting growth mechanism which allows excellent surface coverage and conformal deposition. In particular, area-selective atomic layer deposition (AS-ALD) has gained a lot of attention in recent years due to the possibility of achieving accurate patterns in nanoscale features [1], which renders the technique compatible with the continuous downscaling in electronic devices. In this work, we present the results on the selective growth of Cu2O and metallic Cu by ALD on ZnO and Al-doped ZnO substrates. It was possible to tune the deposited material (Cu or Cu2O) or to completely inhibit the deposition by controlling the substrate conductivity/density of donor defects [2]. Based on this AS-ALD process, Cu2O/ZnO/Al-doped ZnO micro-junctions were fabricated, with the Cu metallic film acting as back electrode. I-V characteristics of the microjunctions, measured by conductive atomic force microscopy, show a non-linear rectifying behavior typical of a p-n junction, which is promising for low-cost all-oxide transparent microelectronics. Semi-transparent Cu2O/ZnO thin film heterojunctions were also fabricated by ALD and reactive magnetron sputtering. The heterojunctions exhibited a self-powered photo-response under 1-Sun illumination and high transmittance in the visible region of the electromagnetic spectrum, which is highly sought for visible photodetection [3]. Finally, this ALD process also allowed the growth of Cu nanoparticles (NP) on highly-conducting ZnO substrates, owing to the Volmer–Weber island growth mode. The Cu NP exhibit localized surface plasmon resonance, tunable from the visible to the near-infrared regions, as confirmed by spectroscopic ellipsometry. The resulting Cu NP/ ZnO device showed an enhanced photo-response under white light illumination with good responsivity values, fast response times, and stability under dark/light cycles [4]. The significant photocurrent detected for this device is related to the hot electron generation at the NP surface and injection into the conduction band of the ZnO. The possibility of tuning the plasmon resonance together with the photo-responsivity of the device is promising for applications related to photo-detection, photonics and photovoltaics. References [1] A. J. M. Mackus, A. A. Bol, and W. M. M. Kessels, Nanoscale 6 (2014) 10941. [2] C. de Melo et al., ACS Appl. Mater. Interfaces. 10 (2018) 37671–37678. [3] C. de Melo et al., ACS Appl. Nano Mater. 2 (2019) 4358–4366. [4] C. de Melo et al., ACS Appl. Mater. Interfaces. 10 (2018) 40958–40965.

Resume : While 3D printing has been growing in the machining industry, with the adaptation of metal 3D printing allowing for creation of structures impossible to obtain by traditional machining, it has also been gaining traction in on the nanoscale. Despite this, only a limited number of materials have been 3D nanoprinted so far, such as electrospun nanofibers [1], and platinum and gold via electron-beam induced deposition [2]. Atomic layer deposition, uniquely among thin film deposition techniques, shares the layer by layer growth nature that universally underpins all 3D printing techniques. It also broadens the material portfolio reachable by other techniques, including growth of thin oxide films. In our contribution, we report on the design and results from a fully spatially constrained precursor delivery ALD reactor to achieve atomic-layer 3D printing We present a full characterization of the TiO2 and Pt ALD process on the experimental prototype. Continuous flow dynamics simulations predict the experimental constraints required to achieve laminar flow behavior between the sample and a first implementation of the spatial ALD micronozzle. A spot size of 300-450 µm is predicted for optimal precursor flow rates. Prototype testing with the TTIP + H2O and MeCpPtMe3 with O3 process results in a reproducible pattern generation with a line resolution of 300-350 µm at predicted flow rates. The growth per pass (GPP) depends on movement speed and precursor flow in a manner similar to classical ALD growth, and the GPP obtained in optimized conditions is similar to the GPC values reported in ALD. The temperature window, crystallinity, and film properties are compared with existing temporal and spatial ALD processes. References: 1. Minhee Lee, Ho-Young Kim. Toward Nanoscale Three-Dimensional Printing: Nanowalls Built of Electrospun Nanofibers. Langmuir 2014 30 (5), 1210-1214. DOI: 10.1021/la404704z 2. Robert Winkler, Franz-Philipp Schmidt, Ulrich Haselmann, Jason D. Fowlkes, Brett B. Lewis, Gerald Kothleitner, Philip D. Rack, Harald Plank. Direct-Write 3D Nanoprinting of Plasmonic Structures. ACS Applied Materials & Interfaces 2017 9 (9), 8233-8240. DOI: 10.1021/acsami.6b13062

Resume : Human brain cognitive functions rely on the emergent behavior of biological neural networks composed of 10^14 – 10^15 synaptic connections. The information processing and memory functionalities are regulated by the changes in the synaptic strength in response to neuron activity (synaptic plasticity), while the high network connectivity provides robustness, adaptability, and fault tolerance to the system. With the aim of emulating working principles of the human brain and its effectiveness, Artificial Neural Networks (ANN) have been developed for the realization of brain-inspired computing systems, outperforming classical computation and even surpassing humans in specific tasks. However, further development of Artificial Intelligence (AI) requires new hardware architectures beyond von-Neumann computing able to implement neuromorphic-type of data processing. In this scenario, memristive devices acting as artificial synapses represent promising building blocks for hardware implementation of ANN. The physical mechanism is related to atomic reconfiguration under proper electrical stimulation, involving nanoionic effects that lead to the formation/rupture of nanofilaments responsible for the variation of the device resistance. Top-down architectures based on crossbar arrays of memristive devices have demonstrated their capability to implement neuromorphic-type of data processing with supervised and unsupervised learning [1]. However, it is hard for such rigid top-down architectures to emulate typical features and topology of biological neuronal circuits, where the principle of self-organization governs both structure and function and provides high connectivity, adaptability through reconnection and rewiring, and long‐range spatiotemporal correlation. As a more biologically plausible alternative, memristive networks consisting of many self-assembled nano-objects have been proposed [2]. The talk will focus on self-organized memristive nanowire (NW) networks, showing that such systems can emulate typical neuromorphic features such as homo and heterosynaptic plasticity, thanks to rewiring and reweighting effects observed in NWs and NW junctions, respectively [3]. Finally, a perspective will be given on the possibility of processing spatiotemporal inputs in multiterminal configuration for in-materia (i.e. hardware) implementation of unconventional neuromorphic computing paradigms, such as reservoir computing. [1] Xia Q. et al., Nature Materials 18:4, pp 309-323, 2019 [2] Kuncic Z. et al., Advances in Physics: X 6:1, pp 1894234, 2021 [3] Milano G. et al., Advanced Intelligent Systems 2:8, pp 2000096, 2020

Resume : Semiconducting metal oxide (SMO)-based gas sensors, which known as a promising gas sensor type, need to improve their gas selectivity toward various gas molecules. In this study, a facile and easy post-modification method is proposed to tuning the gas selectivity by functionalizing the surface of SnO2 nanowires (NWs) with self-assembled monolayer (SAM) molecules. This can be realized by forming specific chemical recognition moieties on the surface of the SnO2 NWs, and they induce the chemical affinity-driven interaction between gas molecules and the functionalized sensors. Gas sensing selectivity was simply modulated as the functionalized SAM molecules changes, which allowed fine-tuning of the gas selective sensor surfaces. The success of SAM modification was analyzed by infrared spectroscopy, X-ray photoelectron spectroscopy, and thermogravimetric analysis, whereas selective gas sensing being investigated under various sensing conditions. The selective gas sensing results were also supported by the molecular dynamics simulations. The gas-selective sensing and surface passivation effect was observed for SAM-functionalized SnO2 NW-based gas sensors, and this concept could be generally expanded to other types of SMO-based sensing platforms.

Resume : Hybrid materials combining metallic nanoparticles (NPs) and polymers has stimulated a large effort to make new optical, electronic and magnetic 1–3 properties emerging. Such composite nanomaterials have the potential of improving the functionality of devices ranging from information storage to microelectronic sensors 4,5. In this context, hybrid nanomaterials combining platinum (Pt) nanoparticles (NPs) and poly(γ-benzyl-L-glutamate) (PBLG) in α helice conformation were investigated by in situ alternative-current impedance spectroscopy as a function of temperature, applied DC bias voltages and PBLG polymerization degree. TEM images of the hybrid materials show a lamellar structure, made possible by Pt, whose organization depends on the degree of polymerization. The corresponding Nyquist’s plots generated from the impedance spectroscopy data show that for each degree of polymerization, a perfect semi-circle typical of an equivalent electrical circuit consisting of parallel resistance R and capacitance C plus a series resistance Rs is observed. The R and C values are obtained using a fitting procedure. This procedure allows determining the relaxation time constant, which is interpreted as the characteristic time of a dipolar relaxation process. Variations of τ with temperature are well described by Arrhenius’s law which allows to extract the activation energy of the relaxation process. We found that the activation energy is around 0.1 eV whatever the DP of the PBLG. It is comparable to the stretching vibration energy of the CN bond in PBLG, which is in favor of a conduction process involving polaronic coupling and hopping. The evolution of the activation energy with applied DC Bias voltage and the polymerization degree reveals a piezo-electric effect induced by the presence of the Pt NPs. This piezo-electric effect is not present in the pure PBLG reference sample and is due to the orientation of the dipoles carried by the α helice and to the lamellar structure of the hybrid Pt-PBLG nanomaterial. We will discuss the obtained results and show that impedance spectroscopy under applied DC bias is able to address the physics of dipole relaxation and charge carrier dynamics in polymer/nanoparticle nanostructured hybrid materials. References: 1. Kao, J., Thorkelsson, K., Bai, P., Rancatore, B. J. & Xu, T. Toward functional nanocomposites: taking the best of nanoparticles, polymers, and small molecules. Chem. Soc. Rev. 42, 2654–2678 (2013). 2. Mei, S., Staub, M. & Li, C. Y. Directed nanoparticle assembly through polymer crystallization. Chem. Eur. J. 26, 349–361 (2020). 3. Yi, C., Yang, Y., Liu, B., He, J. & Nie, Z. Polymer-guided assembly of inorganic nanoparticles. Chem. Soc. Rev. 49, 465–508 (2020). 4. Huynh, W. U., Dittmer, J. J. & Alivisatos, A. P. Hybrid nanorod-polymer solar cells. Science 295, 2425–2427 (2002). 5. Balazs, A. C., Emrick, T. & Russell, T. P. Nanoparticle polymer composites: where two small worlds meet. Science 314, 1107–1110 (2006).

Resume : The emulation of human skeletal muscles has brought to the idea of actuators and several materials have been studied so far, with different contractile mechanism [1, 2]. In order to imitate the natural synchronous contractile mechanism of human muscles, it is necessary to combine: (i) the employment of elastomeric biopolymer with high force-to-weight ratio and flexibility; (ii) a manufacture technique capable to create nano-structured materials; (iii) a motor system simply activated/disactivated by electrochemical stimuli using low voltage [3]. To this aim, the introduction of artificial molecular machine, giving a linear contractile/relaxation movement, in polymeric nanofibers have been envisioned through electrospinning [4]. Electrospinning is a suitable technique to produce bundles of fibers, with hierarchical structure, resembling the skeletal muscle myofibrils and myofibers [5]. In this work, we present and discuss the morphological and mechanical properties of the polymer containing suitable molecular machines, and the electrochemical results by using model molecules of molecular machines. The purpose is to demonstrate that it is possible to integrate molecular machines compounds into polymeric fibers, guarantee the alignment of molecular machines in respect of the fiber axis and electrochemically stimulate the active molecule inside the polymer fibers, thus opening a new scenario in electrochemically responsive soft actuators. [1] M Wei, Y. Gao, X. Li, M.J. Serpe, Polymer Chemistry, 2017, 8 (1), 17-143. [2] S.M. Mirvakili, I.W. Hunter, Adv. Materials, 2018, 30 (6), 1704407 [3] M. Franke, A. Ehrenhofer, S. Lahiri, E.-F. M. Henke, T. Wallmersperger, A. Richter, Front. Robot. AI, 2020, 7, 510757 [4] V. Fasano, M. Baroncin, M. Moffa, D. Iandolo, A. Camposeo, A. Credi, D. Pisignano, J. Am. Chem. Soc., 2014, 136, 40,14245–14254. [5] C. Gotti, A. Sensini, A. Zucchelli, R. Carloni, M.L. Focarete, Appl. Mater. Today 2020, 20, 100772. Acknowledgments This work was supported by the European Union within the Horizon 2020 Research and Innovation Programme (Grant No. 801378 MAGNIFY project https://www.magnifyproject.eu/). All the Partners are acknowledged for the fruitful discussions.

Resume : Developing smart materials that can respond to an external stimulus is of major interest in artificial sensing devices able to read information about the physical, chemical and/or biological changes produced in our environment. Additionally, if these materials can be deposited or integrated on flexible, transparent substrates, their appeal is greatly increased. The first [BEDT-TTF = bis(ethylenedithio)- tetrathiafulvalene based quasi-two-dimensional organic superconductor β-(BEDT-TTF)2I3 was first reported back in 1984.[1] Soon it became clear that ion radical salts (IRSs) derived from BEDT-TTF exhibit tune-able electronic band structures; therefore, such molecules are excellent building blocks for engineering a rich and diverse family of organic crystalline metals and semiconductors. Thanks to strong electron−electron and electron−phonon couplings, their anisotropic electronic structures exhibit many fascinating electronic and structural phase transitions, which can be controlled by external stimuli such as light, temperature, strain, pressure, and humidity, among others. Nevertheless, it is necessary to engineer these crystals into a proper material for sensing applications. This is done by forming poly-crystalline layers of IRSs, derived from BEDTTTF-based conductors, in nano-composite bilayer (BL) films. Such systems can be further tuned by choosing the nature of the IRSs enabling high sensitivity towards strain, pressure, temperature or even contact less radiation sensing i.e. bolometers.[2,3] In another very recent example, bilayer films, composed of conducting poly-crystalline layers of two dimensional BEDT-TTF-IRSs, hydroresistive sub-micron sized crystals on top of a polymeric host matrix permit to electrically monitor relative humidity in a stable and fully reversible fashion.[4] At the percolation threshold, fascinating novel optoelectronic properties emerge (Insulator semiconductor-like metal transition).[5] Mechanisms of responses are discussed and correlated with fundamental properties of charge transport in these systems. This sensor platform enables combining high electrical performance of single crystals with processing properties of polymers towards a simple, low-cost and highly sensitive platform for applications in robotics, biomedicine and human health care. References: 1. E. B. Yagubskii, I. F. Shchegolev, V. N. Laukhin, et.al., JETP Lett., (1984), 39, 12. 2. E. Laukhina, R. Pfattner, L. R. Ferreras, et. al., Adv. Mater., (2009), 21, 1-5. 3. R. Pfattner, V. Lebedev, E. Laukhina, et.al., Adv. Electr. Mater., (2015), 1, 1500090. 4. R. Pfattner, E. Laukhina, L. Ferlauto, et.al, ACS Appl. Electr. Mater., (2019), 1, 1781. 5. R. Pfattner, et.al, (2021), submitted.

Resume : Helium Ion Microscopy (HIM) is providing best resolution Nobel gas focused ion beam (FIB) based imaging and nanofabrication capabilities [1, 2]. I will address in particular low on fluence modification of materials properties with only negligible material removal. Examples in the part will include the modification magnetic, superconducting, electrical and optical properties in metals, semiconductors and 2D materials. I will show how the HIM can be used to create arbitrary shaped nano-magnets [3] and tailor their magnetic properties, with minimal morphological modifications. We use a set of in-situ probes to follow the change of the magnetic properties during irradiation to allow optimized fluence delivery [4]. Similarly, we can use the probes to characterize transistors build from 2D materials and follow the change of their electrical properties during ion beam irradiation. Finally, I will present results from a recent collaboration in which we grew FIBID superconducting tungsten nanowires to study the movement of flux vortices [5]. This work has been supported by the Horizon2020 project npSCOPE (GA: 720964) and the COST Action FIT4NANO (CA19140). [1] Gregor Hlawacek, Vasilisa Veligura, Raoul van Gastel, and Bene Poelsema. Helium ion microscopy. Journal of Vacuum Science and Technology B, 32(2):020801, 2014. [2] Gregor Hlawacek and Armin Gölzhäuser, editors. Helium Ion Microscopy. NanoScience and Technology. Springer International Publishing, Switzerland, 2016. [3] Magnus Nord, Anna Semisalova, Attila Kákay, Gregor Hlawacek, Ian MacLaren, Vico Liersch, Oleksii M. Volkov, Denys Makarov, Gary W. Paterson, Kay Potzger, Jürgen Lindner, Jürgen Fassbender, Damien McGrouther, and Rantej Bali. Strain anisotropy and magnetic domains in embedded nanomagnets. Small, page 1904738, 2019. [4] Peter Dunne, Ciaran Fowley, Gregor Hlawacek, Jinu Kurian, Gwenael Atcheson, Silviu Colis, Niclas Teichert, Bohdan Kundys, Munuswamy Venkatesan, Jürgen Lindner, Alina Maria Deac, Thomas M. Hermans, J. M. D. Coey, and Bernard Doudin. Helium ion microscopy for reduced spin orbit torque switching currents. Nano Letters, 20(10):7036–7042, 2020. [5] Pablo Orús, Rosa Córdoba, Gregor Hlawacek, and José María De Teresa. Superconducting properties of in-plane W-C nanowires grown by He+ focused ion beam induced deposition. Nanotechnology, 32(8):085301, 2020.

Resume : Two-dimensional materials offer a unique platform to study thermal transport in the nanoscale. In this presentation the current understanding of phonon thermal transport will be reviewed, starting from materials with very high thermal conductivity, such as graphene and hBN to transition metal dichalcogenides (TMDs), which show rather moderate thermal conductivity. I will cover our recent efforts on tuning the phonon mean free path and consequently the thermal conductivity in TMDs by various means, such as introducing defects, grain boundaries, changing the thickness or combining different layered materials. We will discuss the case polycrystalline MoS2 and PtSe2 where the grain size, their orientation and distribution play important roles in controlling both the in-plane and cross-plane thermal transport. In the case of single crystal membranes the sample preparation is crucial to eliminate effects of imperfections and contamination focusing on the thickness dependence of the thermal conductance. Finally, the role of the surface and interfaces will be discussed in MoS2–based heterostructures. On the methodological part, the sources of errors in the determination of thermal properties, emerging challenges and outstanding questions concerning phonon transport in TMDCs will be discussed. Work in collaboration with X. Peng, E. Chavez Angel, A. El-Sachat, F. Alzina and C.M. Sotomayor Torres

Resume : Two-dimensional layered materials belonging to the class of Transition Metal Dichalcogenides (TMDs) have recently emerged as promising active layers for optoelectronics thanks to their tunable bandgap, high optical absorption coefficient and excellent mechanical and transport properties [1]. Two main challenges have to be faced in view of the real world exploitation of TMDs in energy harvesting applications: i) development of large area growth techniques to overcome the limits of current micrometer scale mechanically exfoliated flakes; ii) poor optical absorption due to limited thickness which is reduced at the atomic level. Increasing the effective absorption in ultra-thin films requires for innovative light trapping strategies. To this end, we recurred to Laser Interference Lithography to fabricate large area (cm2) periodically nanostructured substrates to be used as templates for conformal growth of few-layer MoS2 films. Due to the template periodicity, diffractive anomalies emerge at the interfaces of the 2D material, bending and confining light into the corrugated MoS2 layer. As a result, a broadband and tunable absorption enhancement is demonstrated [2-3]. Because of the large area and high throughput achievable, nanostructured TMDs films may have a strong impact in the field of 2D layered nanophotonics, featuring broadband photon harvesting. [1] ACS Photonics 2017, 4, 2962−2970 [2] ACS Appl. Mater. Interfaces 2021, 13, 13508−13516 [3] Nanoscale, 2020, 12, s24385-24393

Resume : Molybdenum disulfide (MoS2), one of the most represented TMDs, has been considered as the promising thermoelectric materials for generating electrical energy from temperature gradient, due to the large Seebeck coefficient of ∼50 mV/K and ∼7 mV/K for the monolayer and bulk, respectively. However, the fabrication of MoS2-based thermoelectric devices have not yet been reported. Because of the relatively high thermal conductivity of MoS2 (kMoS2) which increases from ~ 25 W/mK to ~ 100 W/mK when the thickness increases from single layer to bulk, a low thermoelectric figure of merit value of MoS2-based device of 0.5 is expected at room temperature. While the main focus so far has been on the electrical properties of MoS2, less attention has been paid to tuning its thermal conductivity. In this work we have studied two possible ways of reducing kMoS2: reduction of thickness and nano-patterning. The values reported so far on the thermal conductivity of single-crystalline MoS2 show significant spreading, depending on the sample preparation and measurement technique. Therefore, we first systematically studied the kMoS2 of large-area, free-standing single-crystalline membranes using two-laser Raman thermometry. We found that kMoS2 decreased from ~89 W/mk to ~ 27 W/mk to when the thickness decreased from to 40 nm to about 4.5 nm. After the nano-patterning of these membranes, we found the thermal conductivity decreased significantly, over 100 times. The results are discussed together with the theoretically investigated phonon scattering in the system. Our findings open up a possibility for tuning the thermal conductivity in a facile manner to improve the thermoelectric devices based on the layered systems.

Resume : Cluster superlattice membranes (CSLMs) consist of a highly regular cluster lattice, grown on a suitable template like graphene or hexagonal Boron-Nitride on Ir(111) , which is embedded in a host matrix material (e.g. amorphous carbon [a-C]). The membrane can be removed from the template and is stable as a free-standing 2D material [1]. A wide variety of cluster materials, the controllable size of the clusters down to the single atom limit, the choice of the template layer and possible host matrix materials make this fabrication process a highly versatile method to tailor the physical properties of this new 2D material. Potential applications for CSLMs can be found in single electron transistors, phase formation and in electro catalysis, where a cluster superlattice consisting of Pt clusters on Gr, embedded in a-C could be used as an electrode. We present, in detail, the fabrication process of such membranes. The cluster superlattices are grown on graphene on Ir(111), and subsequently embedded in a few nanometer thick carbon matrix. XPS and STM reveal that the carbon embedding is conformal to the clusters, anchors them to the graphene and greatly improves their thermal and mechanical stability. We find that removal of the CSLM from the Ir(111) substrate requires a substantial reduction of the binding between template layer and substrate, which can be achieved via annealing at 850 K and assisted by intercalation of Eu at the template/substrate interface. The removal of the CLSM from the substrate is then performed via conventional hydrogen bubbling. TEM was used after the removal to confirm the presence of the cluster superlattice inside the free standing membrane. [1] Hartl, Tobias, et al., ACS nano, 14(10),13629-13637 (2020).

Resume : Ranging from efficient water splitting surfaces and novel solar cells to smart biosensors: titania nanotube arrays constitute a highly functional material for various applications. Using low-energy ion implantation in the 10 keV – 100 keV range, we show a promising route to modify the material characteristics while preserving the amorphous structure of the nanotube arrays. We report on the interplay of phenomenological effects observed upon implantation of low fluences of a few 10^16 ions/cm^2 in the unique anisotropic and nanoporous structure: sputtering vs. re-adsorption and plastic flow, amorphization vs. crystallization and compositional patterning. Using high-resolution element mappings of transmission electron microscopy measurements, we reveal compositional patterning of oxygen and carbon. Especially, partially connected oxide and carbide domains with sizes of about 10 nm are distributed over the whole nanotube array. Our extensive theoretical treatment corroborates the experimental results. We show that the distinct nanotube environment combined with radiation enhanced diffusivity due to ion implantation and related ballistic contributions provide advantageous conditions for patterning. By applying a generalized version of the Cahn-Hilliard equation combined with driven alloys and corresponding free energy estimates for the amorphous composite, we derive characteristic length scales of pattern formation. Indeed, density functional theory calculations using amorphous TiO2 cells show that dilute-limit mixing enthalpies are augmented for the carbon and oxygen system. Hence, the compositional patterning of carbon and oxygen is expected by enthalpic and entropic arguments. In contrast, a patterning of fluorine and oxygen is energetically unfavorable and not observed. In fact, the nanotubular geometry promotes the patterning due to an increase of relocation lengths compared to bulk materials. As titania nanotubes are a common basis material for advanced devices, these findings pave the way for a manifold of new optimization strategies of optical and electrical nanotube characteristics. Funding by the Heinrich Böll foundation and German BMBF, Project EYECULTURE (FKZ 161A574C) is gratefully acknowledged. References: A. Kupferer, A. Holm, A. Lotnyk, S. Mändl, S.G. Mayr. Adv. Funct. Mater. 2021. Accepted.

Resume : There are many situations in nature where biology uses phase separation to create complex, structured materials. For example, some birds use phase-separating proteins to create materials with highly ordered microstructure, that give rise to vibrant blue and green colors – without the need for dye molecules. However, it is difficult to replicate biology’s precise control of this process in the lab, as surface tension quickly drives complete separation. Here, I will show how we can gain great control over the phase separation process by the simple addition of a polymer network. Starting with a cross-linked, elastic polymer network swollen by a solvent mixture, we change the temperature or trigger polymerisation to drive demixing. Inclusions nucleate and grow to a stable, uniform size that is tunable by the network cross-linking density. I will explain how we are using this process to replicate structural color, as well as to study various topics such as how soft materials fail, and phase separation inside the cytoplasm of living cells.

Resume : With billions of years of evolution, nature has created a diverse library of structural surface patterns to manipulate a range of interfacial phenomena. The proficiency of natural surfaces to tackle multiple phenomena simultaneously is often the work of complex nanostructure arrays or specific geometric features; and replicating this through synthetic means has been a long-standing challenge within the fabrication community. One such structure that has proved challenging to fabricate but is desired for wide ranging applications, is that of the nanotube. Despite recent progress, fabricating nanotubes with greater complexity (e.g., concentric/binary structures) alongside advanced feature control and large-scale fabrication, remained a synthetic bottleneck. Here, we answer this need and present our work on Spacer Defined Intrinsic Multiple Patterning (SDIMP). Unlike previous atomic layer deposition-assisted patterning, the spacer is applied directly on the pre-patterned target substrate material, serving as an etching mask to generate a multitude of tailored nanotubes. By concept iteration, we further realize concentric and/or binary nanoarrays in silicon, glass, and polymers. To demonstrate the achieved quality and applicability of the structures, we probe how nanotube fine-tuning induces broadband antireflection, and present a surface boasting extremely low reflectance of <1% across the wavelength range 300-1,050 nm. Finally, turning to Slippery Liquid Infused Porous Surfaces (SLIPS), we show the impact of nanostructure morphology on the lubricant retention abilities under dynamic conditions by comparing nanotube, nanohole and nanopillar arrays; revealing a 2-fold improvement of nanotubes when compared to nanopillars.

Resume : Mesoporous thin films are widely used for applications in need of high surface area and good transport properties. A common fabrication process involves the co-assembly of host organic molecules (e.g. block copolymers, surfactants, liquid crystals) with inorganic guest material obtained by sol-gel chemistry. A subsequent calcination in air is applied to remove the organic structure-directing agent. Due the volume contraction associated to solvent evaporation, condensation and template removal, this process often results in the uniaxial film contraction of up to 70% in the direction perpendicular to the substrate, affecting the final porosity, pore shape and pore size. Here, we show that a two-step calcination process, high temperature treatment in argon followed by air calcination, improves various structural parameters of the mesoporous thin films. We use spectroscopy ellipsometry (SE) and environmental ellipsometric porosimetry (EEP) to show that inert processing reduces film shrinkage, resulting in higher porosity and larger pore sizes. Grazing-incidence small-angle scattering (GISAXS) and scanning electron microscopy (SEM) shows that the two-step protocol led to a hexagonally closed-packed mesoporous structure. Finally, we show that inert processing condition is beneficial for applications such as enzymatic storage.

Resume : The ability to organize functional nanoscale components into the targeted architectures promises to enable a broad range of nanotechnological applications, from designed biomaterials to photonic devices and information processing systems. However, we are currently lacking an adaptable and broadly applicable methodology for the 3D bottom-up nanomaterials fabrication with ability to prescribe a structure of organizations and to integrate different types of components. The talk will discuss our progress in establishing a versatile platform for the fabrication of designed large-scale and finite-size nano-architectures from diverse nanocomponents through the DNA-programmable assembly. The recent advances in creating periodic and hierarchical organizations from inorganic nanoparticles, proteins and enzymes will be presented. The use of the developed assembly approaches for generating functional nanomaterials with nano-optical, electrical, mechanical and biochemical functions will be demonstrated.

Resume : Nature-inspired nanopatterning offers exciting multifunctionality spanning antireflectance and the ability to repel water/fog, oils, and bacteria; strongly dependent upon nano-feature size and morphology [1,2]. Broadly, this multifunctionality is inherent to and bridged by the nanocone structure, yet such patterning in glass (SiO2) – a material of great practical importance – remains a bottleneck due to its high chemical stability alongside structuring at the nanoscale itself, which becomes increasingly challenging to manage as the pattern resolution advances (pitch <100 nm). Here, we demonstrate a novel Regenerative Secondary Mask Lithography process which enables customized glass nanopillars through dynamic nanoscale tunability of the side-wall profile and aspect ratio (>7). Our method is facile and versatile, comprising just two steps. Firstly, we generate sub-wavelength scalable soft etch-masks (55-350 nm) through an example of block copolymer micelles or nanoimprinted photoresist. Secondly, we overcome their inherent durability problem – typically addressed by metal/metal oxide incorporation which adds time and complexity – through our innovative cyclic etching. During this etching, the original mask becomes embedded within a protective secondary organic mask, which is tuned and regenerated, permitting dynamic nanofeature profiling with etching selectivity >1:32. We envision that such structuring in glass will facilitate fundamental studies and be useful for myriad of practical applications – from displays to architectural windows. Providing the highly-tunable nature of our method (size/shape/pitch), we tailor glass features and present excellent broadband omnidirectional antireflectivity, self-cleaning, and unique antibacterial activity towards Staphylococcus aureus. [1] T. Mouterde, G. Lehoucq, S. Xavier, A. Checco, C. T. Black, A. Rahman, T. Midavaine, C. Clanet and D. Quéré, Nat. Mater., 2017, 16, 658–663. [2] D. P. Linklater, V. A. Baulin, S. Juodkazis, R. J. Crawford, P. Stoodley and E. P. Ivanova, Nat. Rev. Microbiol., 2021, 19, 8–22.

Resume : The preparation of a highly ordered nanostructured transparent electrode based on a combination of nanosphere lithography and anodization is presented. The size of perfectly ordered pore domains is improved by an order of magnitude with respect to the state of the art. The concomitantly reduced density of defect pores increases the fraction of pores that are in good electrical contact with the underlying transparent conductive substrate. This improvement in structural quality translates directly and linearly into an improved performance of energy conversion devices built from such electrodes in a linear manner.

Resume : Few aspects are as prevalent and important to energy conversion and storage as the dimension control of porous nanomaterial architectures. The study of nanostructure-dependent electrochemical behavior, however, has been broadly limited by access to well-defined nanomaterials with independent control over the pore and wall dimensions. This historic limitation is partially due to reliance upon equilibrating self-assembly processes that obscure nanostructure cause-and-effect since the resulting sample series convolve multiple spatial variables. Persistent micelle templates (PMT) are a new nanofabrication approach based upon kinetic micelle control where the pore diameter and wall thickness are independently tunable.1-6 This approach enables investigations that vary one spatial variable at a time with seamless access from meso-to-macroporous materials and a remarkable ~2 Å precision of tuning. Recent energy device research enabled by PMT will be presented where tailored nanomaterials provide a unique perspective to unambiguously identify nanostructure-property-performance relationships.

Resume : Metallic and dielectric nanoarchitectures are attracting increased attention for optical applications, due to their unique electromagnetic properties.(1) These nanocomposites are prominent in optical metamaterials, which are arti?cially structured materials engineered to gain optical properties not only from their composition, but from their design. Their geometry, size and arrangement can a?ect the propagation of light in an unconventional manner, giving rise to properties which are not available in bulk materials. Metamaterials and nanophotonic devices are classically fabricated by lithography techniques, but alternative simpler techniques are needed to reach characteristic sizes on the tens of nanometers length scale. In this sense, block copolymer (BCP) self-assembly has emerged over the past decade as a practical approach, offering unrivalled opportunities to design nanometric features with controlled periodicity over extensive areas at low energy and technology cost. (2) In this work, we present the high versatility that BCP templating and co-assembly offers for optical metasurface and metamaterial fabrication. In a first step, different molecular weight PS-b-P4VP BCP self-assembled films were used as templates for the fabrication gold arrays, regularly organized in a hexagonal lattice.(3) BCP macromolecular engineering allowed complete tuning of the structural parameters of the created arrays. In a second example, perpendicular lamellar structures of PS-P2VP BCP were used as scaffold to create gold decorated surfaces. (4) In this case, the shape of the produced gold NPs was tuned by varying the metal content within the P2VP lamellae, using different impregnation conditions. This resulted in different gold nanofeature shapes from well-defined Au dots to rodlike particles of increasing aspect ratio. Interestingly, more complex structures were prepared using more elaborated fabrication approaches. In this sense, on-demand bimetallic Au@Al2O3 raspberry-like nanoclusters has been fabricated using BCP multi-layer self-assembly strategy.(5) Finally, BCP co-assembly approach, in combination with the so-called persistent micelle templating method, allows the fabrication of ordered inverse-opal mesoporous dielectric architecture. More specifically, we identify the chromatographic fractionation of a polydisperse amphiphilic PIB-b-PEO BCP as a straightforward method to create tailored inorganic mesoporous thin films. Crucially, we identify the role of molecular weight, composition and dispersity on the resulting pore size distribution.(6) The precise control on the shape, structure, size and materials obtained with the previously described fabrication processes, allows a complete modulation of the optical response of the fabricated materials. AFM, GISAXS, Ellipsometric porosimetry, SEM and X-ray Photoelectron Spectrometry, have been used to follow each step of the fabrication process. Besides, optical properties were studied by variable-angle spectroscopic ellipsometric. (1) D. R. Smith, et al, Phys. Rev. Lett. 2000, 84, 4184. (2) A. Alvarez-Fernandez, et al., Advanced Optical Meterials, 2021, https://doi.org/10.1002/adom.202100175 (3) A. Alvarez-Fernandez, et al, J. Vac. Sci. Tech.. B 2020, 38, 013601. (4) A. Alvarez-Fernandez, et al, Nanoscale Adv. 2019, 1, 849. (5) A. Alvarez-Fernandez, et al, RSC Adv. 2020, 10, 41088. (6) A. Alvarez-Fernandez, et al, Nanoscale 2020, 12 (35), 18455.

Resume : opportunities for confinement and propagation of light at the nanoscale.[1] In-plane orientation of the optical axis, in the direction coinciding with the anisotropy of the HMMs, is desirable for a variety of novel applications in nanophotonics and imaging. To date, most of the HMMs presented in the literature are realized by metal/dielectric multilayers or by electrodeposition in nanoporous templates. Here we will present a novel method for creating localized HMMs with in-plane optical axis, based on the dewetting of block copolymer (BCP)-homopolymer ternary blends. On a flat unpatterned substrate, the thermally induced thin film instability give rise to the formation of micrometric droplets composed by a single and defectless grain, randomly distributed on the surface.[2] On the other hand, when the dewetting of BCP is achieved over topographically defined substrates with micrometric periodicity, a hierarchical pattern composed of well-ordered lamellar or cylindrical nanostructures. The presented solution represent a valuable and cost-effective platform for the subsequent pattern transfer into a metal/dielectric HMM, exhibiting hyperbolic behavior in a broad wavelength range in the visible spectrum. A computed Purcell factor as high as 32 at 580 nm supports the strong reduction in the fluorescence lifetime of defects in nanodiamonds placed on top of the HMM.[3] The realization of BCP-based hierarchical patterns paves the way for an easy fabrication of more complex photonic devices such as photonic hypercrystals [4] and hyperbolic waveguides [5] and provides an additional degree of freedom for the fabrication of graded index elements.[6] [1] N. Meinzer, W. L. Barnes, I. R. Hooper, Nat. Photonics 2014, 8, 889 [2]F. Ferrarese Lupi et al. ACS Nano 2018, 12, 7076 [3] I. Murataj et al. Adv. Optical Mater. 2021, 2001933 [4] E. E. Narimanov, Phys. Rev. X 2014, 4, 041014. [5] D. J. Roth et al. ACS Photonics 2017, 4, 2513 [6]M. Naffouti et al. Sci. Adv. 2017, 3, eaao1472

Resume : The incorporation of two metallic nanoparticles (MNPs) into one system has enormous benefits in achieving advanced multifunctional nanomaterials in diverse applications such as catalysis, Surface-enhanced Raman Scattering (SERS), localized surface plasmon resonance (LSPR) sensors, and photothermal conversion [1]. Recently, an unprecedented approach known as Vapor Induced Phase Separation (VIPS) was developed for the fabrication of precisely shaped gold nanoparticles embedded in a poly (methyl-methacrylate) PMMA layer [2]. The main principle of this technique relies on the self-assembly of PMMA thin layer into nanoholes, which are used as MNPs synthesis reactors. Among several synthetic procedures, VIPS is considered as a powerful and simple route because it provides excellent control of structural properties of NPs. It offers compelling evidence for producing efficient SERS platforms with controlled size, shape, and interparticle gap distances [3,4]. Inspired by this approach, we aim to fabricate multifunctional hybrid nanomaterials such as Ag-Au bimetallic nanoparticles (BNPs). This is a new insight in the synthesis of BNPs by a surface-based strategy. Precisely, we carried out a parametric study dealing with the influence of different experimental parameters on optical and structural properties of monometallic and BNPs. The optical properties of synthesized BNPs substrates were analyzed by micro-extinction and ellipsometric measurements. Ultimately, the significance of the present work lies in assuring the effectiveness of the substrates produced in SERS applications by inducing highly sensitive, stable, and reproducible SERS substrates over a large scale. [1]. M. Chen, Y. He, & J. Zhu, International Journal of Heat and Mass Transfer. 114, 1098-1104 (2017). [2]. R. Omar, A. E. Naciri, S. Jradi, et al., Journal of Materials Chemistry C. 5(41), 10813-10821 (2017). [3]. R. Omar, A. E. Naciri, A. Fahes, et al., Soft Matter. 16(7), 1857-1865 (2020). [4]. S. Akil-Jradi, S. Jradi, J. Plain, et al., RSC advances. 2(20), 7837-7842 (2012).