Solution processing and properties of functional oxide thin films and nanostructures II

Resume : Oxide nanosheets are the oxide equivalents of graphene. They have a thickness of ~1 nm and lateral sizes up to tens of micrometers. They are made by exfoliation of layered oxides in water using a combined acid-base & ion exchange reaction. We investigated the mechanism and kinetics of exfoliation of lepidocrocite-type titanates into Ti1-xO2 nanosheets using time-resolved techniques. In contrast to common knowledge, we found that the exfoliation process is rapid and occurs within minutes, opening up possibilities for large-scale synthesis. Dense nanosheet monolayer films were made by Langmuir-Blodgett (LB) deposition. The conditions for LB deposition of nanosheets on glass and silicon were optimized. The nanosheet films were used as seed layers to form preferentially oriented nanoelectronic oxide films by pulsed laser deposition. SrRuO3, (La,Sr)MnO3 and Pb(Zr,Ti)O3 films were grown on Ca2Nb3O10 and Ti0.87O2 nanosheets. Depending on nature of the seed layer, either [001] or [110] oriented films were formed, which influenced their functional properties. Nanosheet flake size is also shown to have an effect. Micropatterns of different nanosheets by photolithography and lift-off are demonstrated, illustrating the possibility to locally control the orientation of functional films.

Resume : Crystalline nanostructured manganites (MxMnyOz, M=transition or alkali metal) are endowed with interesting electrical, catalytic and magnetic properties; common synthetic routes however often present high energy and/or environmentally unfriendly requirements. Recently, inorganic chemists have been searching for new, greener protocols. Within this framework, we implemented an environmentally safe and low-energy approach to synthesise three different zinc and copper manganites ZnMnO3, ZnMn2O4, CuMnO2. We employed an easy and reproducible hydrothermal route at 180 °C, starting from an aqueous suspension obtained from a coprecipitation of oxalates. The spinel ZnMnO3 is particularly notable as few records of this compound are available in literature and all involve a high temperature (>450 °C) calcination step. For all species, the subcritical hydrothermal approach was shown to play a key role in stabilising phases which are generally achieved at much higher temperatures, and in harsher conditions, thus disclosing an exciting alternative for their synthesis. The crystalline compounds were characterised from a compositional, structural and physico-chemical point of view. This was achieved by complementary analytic tools, such as XRD, SAED, TEM, SEM, XPS, XAS, CHN, ICP-MS. Magnetic characterisation (SQUID) was carried out in order to confirm the presence of a ferrimagnetic/antiferromagnetic behaviour.

Resume : Biferroic materials constitute an emerging class of materials, which combine coupled electric and magnetic dipole orders in the same crystallographic phase. New device applications are expected from the coupling of these parameters, and its technological interest extends from transducers, magnetic field sensors or for information storage industry. Recent studies have proved that heavy rare earth chromites (LnCrO3, Ln = Ho, Er, Yb, Lu or Y) are multiferroics. These perovskite – type compounds belong to the orthorhombic system (Pbnm), and show canted antiferromagnetism (114 – 140 K), and weak ferroelectricity (470 – 516) K. YbCrO3 and LuCrO3 chromites have been synthesized for the first time using a low-temperature citrate-gel precursor route. A high phase purity was obtained from the Rietveld refinements of synchrotron-based powder-XRD measurements. Using these compounds as precursors, novel epitaxial YbCrO3 and LuCrO3 thin films have been grown by PLD on SrTiO3. Structural characterization have been performed by synchrotron based Grazing Incidence XRD and EXAFS measurements. Complementary electronic and morphological characterization have been carried out by XPS and AFM respectively. A complete overview of the synthesis and characterization of heavy rare earth chromites in bulk and thin film form will be presented.

Resume : The term “perovskite” having general formula ABX3, can accommodate a wide variety of elements with the advantage of manipulation in stochiometry for advanced technologies including magnetism, dielectric behavior, conductivity or even multiferroic behavior. The stochiometric changes can lead to obtain double perovskite with general formula A2B'B''O6 which are widely studied so far, where six coordinate sites are occupied by B' and B'', while 12-coordinate sites are occupied by A cation. Additionaly another interesting class of multiferroic compounds with more complex geometry (A3B'2B''O9) have been investigated (Sr3Fe2MoO9 and Sr3Fe2UO9) and reported with strong ferromagnetic properties with TC well above room temperature, which is caused by intrinsic partial disordering over half of the perovskite unit due to random distribution of Fe and Mo/U at B'' positions. The major drawback in the synthesis of the above mentioned quaternary metal oxides is a solid-state reaction (SSR) which requires high- temperature treatment and prolonged sintering time (at least 120 h) for achieving phase purity. We report a successful synthesis of double perovskite Ba3Fe2TeO9, Ba2NiTeO6 and Sr3Fe2TeO9 by novel modified aqueous 'sol-gel' process using citric acid as complexing medium followed by the calcination step. Both compounds have been structurally studied by the powder X-ray diffraction (Rietveld refinement), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and unpolarized Raman spectroscopy. At room temperature, the crystal structure of Ba3Fe2TeO9 is hexagonal, space group P63/mmc (194), with a = 5.7665, c = 14.2024 Å; while Sr3Fe2TeO9 the crystal structure is cubic, with space group Pm-3m (221), and a = 3.9353 Å. Magnetic measurements show the onset of ferromagnetic ordering at 690 K for Sr3Fe2TeO9 compound, while Ba3Fe2TeO9 exhibits an antiferromagnetic transition at 200 K and ferromagnetic like (seen only in small magnetic field) at 100 K. Ideally, Ba3Fe2TeO9 and Sr3Fe2TeO9 double perovskite contains Fe3+ and Te6+ cations, ordered in a way that superexchange interactions between neighboring Fe3+ spins are the nominal mechanism accounts for the magnetism of these materials.

Resume : Multiferroic composites showing a magnetoelectric coupling have attracted high interest for their potential applications in e.g. sensors or multistate data memories. Especially the system BaTiO3/CoFe2O4 has been widely studied and composites of different connectivities (0-3, 2-2, 1-3) have been prepared applying various preparation techniques. In this contribution we report on different solution based synthesis approaches leading to thin films and nanostructured 0-3 composites of BaTiO3 in combination with ferrite spinels MFe2O4 (e.g. M = Co, Ni). Thin films were prepared via spin coating on platinum coated silicon wafers in the form of bilayers, sandwich structures or alternating multilayers. For some samples a strong magnetic anisotropy was observed and magnetic and polarization hysteresis loops prove the presence of ferrimagnetism and ferroelectricity. 0-3 composites were prepared by a polyol-mediated synthesis. Using a sequence of thermal treatments dense ceramics free of secondary phases like BaFe12O19 were obtained. The synthesis was monitored by TGA, XRD and photometric analyses and the final composites were investigated via SEM, EDX, impedance spectroscopy as well as magnetic and magnetoelectric measurements.

Resume : Nanoparticles, including nanowires and nanosheets, are the ideal building blocks for the bottom-up fabrication of functional materials with 2D and 3D geometries. While this approach provides exceptional flexibility to combine different types of building blocks on the nanoscale, a great challenge remains to fabricate a material with macroscopic size. The talk will cover the synthesis of metal oxide nanoparticles with different shapes using nonaqueous sol-gel chemistry. Different strategies will be presented to assemble and process the nanoparticles into thin films and aerogels bridging several orders of length scales. Incorporation of different types of particles within the final body enables subtle tuning of the properties. Selected applications in the field of photoelectrochemical water splitting, gas sensing and lithium ion batteries will briefly be addressed.

Resume : To improve the performances of p-Dye Sensitized Solar Cell (p-DSSC) [1], the synthesis of modified p-type nickel oxide semiconductor, commonly used as a photocathode in such devices, was initiated using a mixed valent nickel oxyhydroxide Ni3O2(OH)4. The decomposition of this precursor in air at temperatures lower than 600°C leads to non-stoichiometric Ni1-xO nanoparticles (from 2 to 60 nm) with tunable nickel vacancies concentration (up to 25% for 2-3nm particle sizes) [2]. According to our chemical characterizations (XRD, TEM, density, chemical analysis, BET measurement…), the nickel vacancies segregate at the surface of the Ni1-xO nanoparticles to create a "core-shell"-like edifice (similarly to our previous work on Zn-deficient Zn1-xO nanoparticles [3]). This "core-shell" is constituted by a dense stoichiometric NiO coated (or terminated) by an oxygen (hydroxide or carbonate groups) surface layer free from nickel atom. The Ni-free surface layer influences drastically the density of the smaller nanoparticles by decreasing it. When the nanoparticles size increases, the density evolves until reaching the theoretical density of stoichiometric nickel oxide for the bigger particles (≥100 nm). Thus, with the control of the particles size, we can also control the Ni non-stoichiometry in Ni1-xO following our "core-shell"-like model. [1]. F. Odobel, L. Le Pleux, Y. Pellegrin, E. Blart, Acc. Chem. Res., 43, 1063−1071, (2010). [2]. B. Polteau, F. Tessier, F. Cheviré, L. Cario, F. Odobel, S. Jobic, Solid State Sci., (2016) http://dx.doi.org/10.1016/j.solidstatesciences.2015.10.007 [3]. A. Renaud, L. Cario, X. Rocquefelte, P. Deniard, C. Payen, E. Gautron, E. Faulques, F. Cheviré, F. Tessier, S. Jobic, Sci. Rep., 5, 12914 (2015)

Resume : Engineering the size and dimension of nanomaterials is promising to endow them with novel properties and broaden their applications. As a typical example, ultra-small nanodots, one kind of nanomaterials, exhibit unique electronic and optical properties due to the quantum confinements and edge effects. Recently, semiconductors with two-dimensional structures, such as transition metal dichalcogenides (TMDs) and black phosphorus (BP), have drawn great attention in electronics, catalysis, biomedicine, sensing and energy storage.[1] However, high-yield production of TMD and BP nanodots is still under investigation and their applications remain to be explored. Herein, we report the preparation of a number of layered TMD nanodots (including MoS2, WS2, ReS2, TaS2, MoSe2, WSe2 and NbSe2) and BP nanodots in high yield.[2,3] All the prepared nanodots have small size and good dispersity. As a proof-of-concept application, the synthesized nanodots mixed with polyvinylpyrrolidone (PVP) are used as active layers for fabrication of memory devices. References [1] X. Zhang, Z. C. Lai, C. L. Tan, H. Zhang*, Angew. Chem. Int. Ed., DOI: 10.1002/anie.201509933 (2016). [2] X. Zhang, Z. C. Lai, Z. D. Liu, C. L. Tan, Y. Huang, B. Li, M. T. Zhao, L. H. Xie, W. Huang, H. Zhang*, Angew. Chem. Int. Ed., 2015, 54, 5425–5428. [3] X. Zhang, H. M. Xie, Z. D. Liu, C. L. Tan, Z. M. Luo, H. Li, J. D. Lin, L. Q. Sun, W. Chen, Z. C. Xu, L. H. Xie, W Huang, H. Zhang*, Angew. Chem. Int. Ed., 2015, 54, 3653–3657.

Resume : Nanotechnology is still holding the promise to increase industries efficiency bringing profoundly new applications, but to achieve this goal specific, synergic and coordinated research involving scientists form different disciplines are necessary to boost nanotechnology. Material science is at the base of nanotechnology. Concerning functional materials, easy and cheap growth techniques for the production of nanostructures in a variety of morphologies are constantly proposed by the research community. Metal oxides represent an assorted and appealing class of materials which properties cover the entire range from metals to semiconductors and insulators and almost all aspects of material science and physics in areas including superconductivity and magnetism. In particular metal oxides in forms of nanowires are interesting materials for their peculiar morphology that assures a high surface to volume ratio necessary to maximize surface related properties like the ones governing chemical sensing transduction principles. When developing 1D nanocrystals the most important requirements are dimensions and morphology control, uniformity and crystalline properties. In order to obtain one-dimensional structures there have to be a preferential growth direction with a faster growth rate in a particular direction. The thermal evaporation and oxidation methods have been used to prepare a variety of oxides such as tin, zinc, copper, nickel, tungsten and will be extensively described since they are among the most explored in the recent papers and the cheapest for single crystal production. Acknowledgements The research leading to these results has received funding from the European Community’s FP7-ICT-2013-10, MSP— Multi-Sensor-Platform for Smart Building Management under the project n° 611887.

Resume : ZnO is a semiconductor with a direct band gap (3.37eV) and a large exciton binding energy (60meV) at room temperature. ZnO nanowires have shown advantages due to their very large surface-to-volume ratio, superior stability owing to high crystallinity and simple preparation methods. As compared to vapor-phase synthesis, liquid-phase synthesis is known for being a very powerful and versatile technique due to its low cost, flexibility, facility and environmentally benign processes. However, a main drawback of liquid-phase synthesis is the difficulty to renew or change precursors during growth, which is often used in vapour-phase synthesis in order to grow nanostructures with very high aspect ratio, or axial heterostructures. Here we demonstrate the cycle growth of ZnO nanowire segments in liquid phase from ZnCl2 and hexamethylene tetramine (HMTA) with homogeneous nucleation, obtained by the step-by-step addition of precursors, leading to a step-by-step increase of the nanowire length without significant increase of their width up to an aspect ratio of ~20. This process strongly contrasts with the direct increase of the concentration of precursors which lead to strong increase of both length and diameter. The involved mechanism could be explained as a competition between the capping effect of Cl- ions and the buffer effect of hexamethylene tetramine that favorises c-growth without increasing diameter. The use of an additional capping agent (polyethylene glycol) increases even further the selectivity of the growth (aspect ratio ~27). The process already shows the direct increase of the nanowire aspect ratio when using the same precursors during the cycles, and could be extended to the growth of axial heterostructures when using different precursors, which is a challenge in liquid phase with homogeneous nucleation.

Resume : Surface chemistry is a key enabler for colloidal nanocrystal applications. In this respect, metal oxide nanocrystals (NCs) stand out from other nanocrystals as carboxylic acid ligands adsorb on their surface by dissociation in carboxylates and protons.[1,2] Here[3] we show that weakly binding ligands such as amines and alcohols chemically convert tightly bound carboxylic acids in non-coordinating amides or esters and thus promote acid/amine and acid/alcohol ligand displacement. Furthermore, ester formation is sustained when the ligand shell is continuously replenished with carboxylic acids, a reaction not occurring in the absence of NCs. We relate this unexpected colloidal nanocatalysis to the dissociative NC(X2) binding motif of carboxylic acids to oxide NCs and we underscore its potential by showing that colloidal HfO2 NCs also catalyze transesterifications. While promising, as it may combine the benefits of heterogeneous and homogeneous catalysis, colloidal nanocatalysis is often problematic since surface-adsorbed ligands, needed for colloidal stability, prevent reagents from reaching catalytically active surface sites. By using reagents as ligands however, chemically driven ligand displacement bypasses this colloidal stability/catalytic activity conundrum, thus turning colloidal NCs into effective nanocatalysts. [1] De Roo, J. et al. J. Am. Chem. Soc. 2014, 136, 9650 [2] De Roo, J. et al. Angew. Chem.-Int. Edit. 2015, 54, 6488 [3] De Roo, J. et al. Nat. Mat. 2016 Accepted

Resume : Chemically synthesized inorganic nanocrystals (NCs) are considered to be promising building blocks for a broad spectrum of applications including electronic, thermoelectric, and photovoltaic devices. We have synthesized monodisperse colloidal nanocubes (4-15 nm edge lengths) of fully inorganic cesium lead halide perovskites (CsPbX3, X=Cl, Br, and I or mixed halide systems Cl/Br and Br/I) using inexpensive commercial precursors [1]. Their bandgap energies and emission spectra are readily tunable over the entire visible spectral region of 410-700 nm. The photoluminescence of CsPbX3 NCs is characterized by narrow emission line-widths of 12-42 nm, wide color gamut covering up to 140% of the NTSC color standard, high quantum yields of up to 90% and radiative lifetimes in the range of 4-29 ns. Post-synthestic chemical transformations of colloidal NCs, such as ion-exchange reactions, provide an avenue to compositional fine tuning or to otherwise inaccessible materials and morphologies. While cation-exchange is facile and commonplace, anion-exchange reactions have not received substantial deployment. Here we present fast, low-temperature, deliberately partial or complete anion-exchange in CsPbX3 NCs. By adjusting the halide ratios in the colloidal NC solution, the bright photoluminescence can be tuned over the entire visible spectral region (410-700 nm). Furthermore, fast inter-NC anion-exchange is demonstrated as well, leading to uniform CsPb(Cl/Br)3 or CsPb(Br/I)3 compositions simply by mixing CsPbCl3, CsPbBr3 and CsPbI3 NCs in appropriate ratios. We also present low-threshold amplified spontaneous emission and lasing from CsPbX3 NCs [3]. We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700 nm) with low pump thresholds down to 5±1 µJ cm-2 and high values of modal net gain of at least 450±30 cm-1. Two kinds of lasing modes are successfully realized: whispering gallery mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 NCs, and random lasing in films of CsPbX3 NCs. Here we also demonstrate that 0.5-1 centimeter large, solution-grown single crystals of MAPbI3 can serve as inexpensive, operating at ambient temperatures solid-state gamma detectors (e.g. for direct sensing of photons with energies as high as mega-electron-volts, MeV) [4]. Such possibility arises from extremely high room-temperature mobility(µ)-lifetime() product of 10-2 cm2 V-1, low dark carrier density 109 - 1011cm-3 and low density of charge traps 3 × 1010 cm–3 , and high absorptivity of hard radiation by lead and iodine atoms. 1. L. Protesescu et al. Nano Letters 2015, 15, 3692–3696 2. G. Nedelcu et al. Nano Letters 2015, 15, 5635–5640 3. S. Yakunin et al. Nature Communications 2015, 9, 8056. 4. S. Yakunin et al. submitted

Resume : The (0001)-oriented ZnO continuous layer and vertical nanowires have been prepared on a (0001)-oriented Ga:ZnO layer/soda-lime glass substrate with a small lattice mismatch by electrodeosition in simple zinc oxide aqueous solutions at 336 K. The morphology of ZnO changed from a continuous layer to vertical nanowires with decrease in the zinc nitrate concentration. The (0001)-ZnO continuous layer mainly emitted a visible light due to the native defects, and (0001)-ZnO vertical nanowires emitted a strong ultraviolet light originating from the recombination of bound excitons at room temperature without visible light emission, indicating the high quality. The ZnO continuous and vertical nanowires were estimated as a scintillator in Japan Synchrotron facility, SPring8. The (0001)-ZnO vertical nanowires showed a high luminous efficiency compared with that for the ZnO continuous layer, and the spatial resolution of 2 μm could be observed for the (0001)-ZnO vertical nanowires and was slightly larger than 0.8 μm for Ce3+:Lu3Al5O12(LuAG) scintillator generally used as the scintillator.

Resume : An important economic improvement of white light emitting diode is based on the use of lanthanide-free phosphors that are supposed to convert UV light into visible one, thanks to down-conversion (DS) process. ZnO nanoparticles (NPs) have aroused an increasing interest since they possess a variety of intrinsic defects that provide light emission in the visible range without the introduction of any additional impurity. However, high photoluminescent quantum yield (PLQY), green/yellow emission, stable dispersion and easy scale–up process are expected for industrial applications. Li-doping and polymer surface modifications of ZnO nanoparticles are mainly used in order to reach high PLQY (>30%) but PLQY decay over few days, uses of sophisticated polymers or multi-step reactions are the main issues for industrial implementation. Herein, we present a quick and convenient chemical solution approach to get unique mesospheric self-assembly hybrid ZnO system with intense (PLQY = 40-75%) and stable visible emissions. We also demonstrate that the use of mixture of commercial polyacrylic acid-based polymers can provide scalable amounts of ZnO NPs clear water suspensions that can be dried and dispersed again in water without compromising the functional performance (e.g. transparency and PLQY) of the final DS layer. We will then address the effects of the ZnO NPs surface functionalization - such as nature, molecular weight, concentration, ratio of the PAA-based polymers and self-assembly process- on the enhancement of the efficiency of DS thin films in LED technology.

Resume : Zinc gallate, ZnGa2O4, is a wide band gap (4.5-5 eV) semiconductor characterized by a normal spinel structure (AB2O4) in which Zn2+ and Ga3+ ions occupy the tetrahedral (A) and octahedral (B) coordinated sites respectively. As oxide-based phosphor, it has gained growing attention in the last twenty years due to its possible application in the field of TFED, FED and VFDs. Moreover, zinc gallate based phosphors have recently grown increasing interest as long-lasting luminescent materials opening new opportunities for their employment in night/dark environment vision displays and for in vivo optical imaging. In this framework, ZnGa2O4:Cr3+ represents a promising solution to obtain a red/near-infrared persistent emission; the presence of peculiar lattice defects seems to be fundamental to get trapped free carriers and then allow their slow detrapping and radiative recombination. The study presents the sol-gel synthesis of luminescent Cr3+ - doped ZnGa2O4 thin films with zinc gallate as the main crystalline phase, characterized by a highly homogeneous thickness. Microstructural, morphological, compositional and optical properties have been investigated through XRD, SEM, XPS and optical spectroscopy. A strong variation of the morphology and the optical properties has been observed by applying different annealing treatments: upon increasing the temperature of the treatment, an increment of the grain dimensions and an increase of the intensity of red emission have been detected.

Resume : Among the various ZnO nanostructures grown by solution based techniques, the nanowalls (NWLs) are extremely interesting because of their huge surface-to-volume ratio and their extremely thin wall thickness. They are composed of ZnO based nanosheets (~10 nm thick) grown vertically on Al (covered) substrates and packaged as a film with an intertwined, honeycomb-like pattern. We recently reported some promising applications of ZnO NWLs in pH sensing [1] and photocatalysis [2]. Here we report on the growth mechanism of NWL obtained by chemical bath deposition (at 70−95 °C), elucidating the roles of pH and growth time on the NWL film. It is believed that hydroxyl ions of the synthetic solution react with Al to form the Al(OH)4¯ complex, which binds to the Zn2+ terminated surfaces and block the ZnO growth along the (0001) direction giving birth to the nanosheet shape. We propose the use of anodized Al as a way to enhance the growth rate, density and quality of the NWLs film. In addition, we report on the synthesis of ZnO nanoflowers (NFL), obtained by centrifugation and sonication of a 90 °C heated solution containing Zn nitrate, HMTA and NH4F. Also ZnO NFL are composed of nanosheets, but packaged as spheres (1-3 um in size) and homogeneously nucleated in the synthetic solution. F¯ ions are believed to act as binder to the Zn2+ terminated surfaces causing the nanosheet shape. Sensing tests of ZnO NWL and NFL will be presented and discussed. [1] Maiolo et al., Appl. Phys. Lett. (2014) [2] Iwu et al., Cryst. Growth Des. (2015)

Resume : Zirconia (ZrO2) can adopt three different crystalline phases, i.e. monoclinic, tetragonal and cubic. The use of zirconia in its applications is in general depending on its crystalline phase, e.g. cubic ZrO2 is applied in oxygen sensors, tetragonal ZrO2 is used as high performance transformation-toughened ceramics and can catalyze ethanol formation from syngas, while monoclinic ZrO2 will catalyze isobutanol formation from syngas and is important for gate dielectrics and bioactive coatings. In this work, we demonstrate the possibility to synthesize both pure monoclinic or pure cubic ZrO2 nanocrystals by solely changing the precursor using a microwave-assisted solvothermal treatment. We used GC-MS analysis on the reaction mixtures to proof that the change in crystal structure rises from a difference in reaction mechanism induced by the release of a strong acid during synthesis. The as-synthesized ZrO2 nanocrystals (cubic or monoclinic) are small in size (3 – 10 nm), yet aggregated and thus showing a low dispersibility. Aggregrate-free NPs are generated through surface-functionalization of the NPs with long chain ligands, providing stabilization in apolar solvents via steric hindrance. Solution 1H NMR was used to study the details of this post-modification step and the surface chemistry of the resulting aggregate-free NPs. This led to the conclusion that not only a different crystal structure yet also a different surface chemistry is obtained depending on the used precursor.

Resume : Semiconductor PbS and PbS/CdS quantum dots (QDs) have attracted a great attention due to strong absorbance in the visible, emission in the near infrared region and relatively high quantum yield. These optical properties make them a good candidate for applications such as luminescent tagging, sensing, bio-imaging and in photovoltaics. Emission tunability and stability are important issues with colloidal PbS QDs. CdS shell grown by cation exchange in solution followed by heat-treatment can provide control over these two features. This will be the first report on low temperature synthesis and heat-treatment of colloidal PbS and PbS/CdS QDs. We will discuss the effect of heat-treatment parameters such as temperature and time on the properties of the PbS/CdS core-shell QDs such as emission wavelength, absorption, quantum yield, lifetime and stability. This enables us to prepare QDs with emission at different wavelengths from a single PbS/CdS QD source, which has a tremendous synthetic advantage over the existing methods.

Resume : Mechanistic insights into shape and structure formation of metal oxide composites and related knowledge about their stability are critical to our understanding of how the chemical environment affects materials functional properties such as optical absorption or light-induced surface reactivity.[1] The growth and stability of metastable Na2Ti3O7 nanowires which are composed of titanate nanosheets have been investigated in aqueous dispersions by using different analytical methods.[2] Transformation processes such as nanosheet delamination, nanoscroll formation or dissolution-recrystallization processes leading to colloidal anatase nanoparticles will be discussed. Processes at the solid-liquid interface such as nanosheet delamination have been tracked by time-resolved second harmonic generation measurements for the first time.[3] Aiming at the perfect intermixture between NaTaO3-based cubes and Na2Ti3O7 based nanowires under preservation of their distinct morphologies we explored the potential of different precursor states. The mechanistic insights obtained enable advanced strategies in alkaline reaction media for the growth of entangled nanostructures with improved photoelectronic properties. [1] Berger and Diwald, Defects in Oxide Nanoparticles Systems, Springer Ser. Surf. Sci., 58, (2015) 273-301 [2] Baumann et al. Chem. Eur. J., 9 (2013) 10235 [3] Schürer et al. J. Phys. Chem. C, 115 (2011) 12381

Resume : The aim of this work is to study the electrical characteristics of the nanoscale SOI Tri-Gate n-channel fin field-effect transistor (FinFET) structure with 8 nm gate length using ZrO2 as gate dielectric material. The numerical device simulator, ATLAS™ is used to simulate the structure in three dimensions with different models under consideration. The drain current, transconductance, threshold voltage, subthreshold swing, leakage current, drain induced barrier lowering (DIBL), and IOn/IOff current ratio are analyzed in the various biasing configuration. In addition, FinFET device with a high value of gate dielectric constant exhibits much better performance compared to the Si3N4 dielectric material, which is desirable for high performance low-power/low-voltage applications. It is found that increasing the high-k value was beneficial in reducing the subthreshold swing, DIBL, and leakage current.

Resume : Silica nanowires (SiO2NWs) have attracted considerable attention over the last decades due to their diverse properties and broad range of applications. These include the capacity to emit strong blue light, the versatility to be functionalized in order to respond to several targets or their potential use as protective layer against corrosion by exposure to the environment. In this regard, the use of a metal substrate is of paramount relevance; therefore, an adequate contact between the substrate and the nanostructures is required. This work presents a novel procedure for the growth of SiO2NWs directly from polycrystalline copper foils. This mechanism consists of a single-step thermal process at 900°C with Cu acting as both substrate and catalytic agent. As a result, nanowires with diameters ranging from 50 to 100 nm grow uniformly throughout the substrate in a branched structure. The Energy Dispersive X-ray Spectroscopy (EDX) elemental mapping performed on the nanowires revealed the presence of catalytic protrusions at the bottom of the nanowires, which suggested the vapor-liquid-solid (VLS) as the main mechanism of the SiO2NWs. Additionally, the Grazing-Incidence X-ray Diffraction (GIXRD) analysis conducted on the SiO2NWs/Cu sample after the synthesis showed no presence of copper oxide peaks, which evidences the good coverage of the substrate by the nanowires and the protective action of the latter. Furthermore, a low-pressure synthesis at the same temperature was performed achieving an increased efficiency on the process, obtaining vertical growths of the SiO2NWs over 500 nm from the substrate.

Resume : SiO2 nanowires gain scientific and technological interest in application fields ranging from nano-electronics, optics and photonics to bio-sensing. Furthermore, the SiO2 nanowires chemical and physical properties, and so their performances in devices, can be enhanced if decorated by metal nanoparticles (NPs) due to local plasmonic effects. We propose a simple, low-cost and high-throughput three-steps methodology for the mass-production of Au nanoparticles coated SiO2 nanowires. It is based on: 1) production of the SiO2 nanowires on Si surface by solid state reaction of a Au film with the Si substrate at high temperature; 2) sputtering deposition of Au on the SiO2 nanowires to obtain the nanowires coated by a Au film; 3) furnace annealing processes to induce the Au film dewetting on the SiO2 nanowires surface. Using scanning electron microscopy analyses, we followed the change of the Au nanoparticles mean radius r versus the annealing time. The evolution of r was analyzed versus the annealing temperature T finding valid an Arrhenius-like behaviour extracting values for the characteristic activation energy (0.28 and 0.36 eV for Au film thickness of 20 and 40 nm, respectively) of the dewetting process of the Au film on the SiO2 nanowires surface. Such a study can allow the tuning of the nanowires/nanoparticles sizes for desired technological applications.

Resume : Surface chemistry and ligand exchange are essential to bridge the gap between nanocrystal (NC) synthesis and their application in nanocomposites. Although we recently contributed to the understanding of ligand exchange at metal oxide NCs in nonpolar media[1-2], the exchange of native, hydrophobic ligands with polar ligands is still poorly understood. Here we present a new, versatile ligand exchange strategy for the phase transfer of carboxylic acid capped metal oxide NCs to polar solvents, based on small amino acids as the incoming ligand. To gain insight in the exchange mechanism, we study this system with a combination of FTIR, zeta potential measurements and solution 1H NMR techniques. The detection of surface-associated, small ligands with solution NMR proves challenging in this respect. Tightly bound amino acids are undetectable but their existence can be proven through displacement with other ligands in titration experiments. Alternatively, we find that methyl moieties belonging to bound species can circumvent these limitations because of their improved relaxation properties as a result of internal mobility. These insights will facilitate further research, characterization and development of ligand exchange methods with small ligands as they apply to any binding event between a short ligand and a large entity. [1] De Roo, J. et al. J. Am. Chem. Soc. 2014, 136, 9650 [2] De Roo, J. et al. Angew. Chem.-Int. Edit. 2015, 54, 6488

Resume : Inspired by nature, superhydrophobic surfaces, the extremely high water contact angle with small sliding angle, have been of growing interests for their potential applications including self-cleaning materials. Specifically, an optically transparent superhydrophobic coating, exhibiting self-cleaning property, is highly desirable for the development of optical devices such as smart windows and solar panels. Herein, we developed a facile approach for the fabrication of transparent superhydrophobic surfaces enabled by a simple solution-process and chemical modification. These new nonwetting film coating methods are readily fabricated by heterogeneous oxide nanoparticle mixture to control micro/nano dual scale surface roughness and transparency. Attractive nonwetting film coating surface displayed high water contact angle (>150°) and small sliding angle (<5°), showing excellent superhydrophobicity, great optical transparency (>90 %) and stability. Furthermore, this method showed the application for a wide range of substrates including semiconductors, papers, cotton fabrics, and even flexible plastic substrate. Finally, self-cleaning effect was demonstrated using carbon dust on these film coated surface.

Resume : Fuel cells refer to a power generator that coverts chemical potentials into electrical and thermal energy. The fuel cell operation relies on electrochemical reaction that directly ionizes fuel chemicals without any combustion or mechanical processes. For this reason, fuel cell can generates electrical power silently and relatively efficient with minimized harmful emission. Solid oxide fuel cells (SOFCs) are a type of fuel cells made of ceramic electrode and electrolytes. As SOFCs operate at relatively high temperatures around 600-1000 °C, charge transfer reaction at electrode surface can occur relatively fast without the help of precious catalyst such as platinum. Therefore, hydrocarbon or carbon oxide compounds can be directly used as fuel for SOFCs with no pre-reforming. The charge transfer reaction is followed by ion transport across either electrode or electrolyte layers. This ion conduction accounts for a considerable amount of energy loss mostly in the form of resistance heat. Therefore, thickness of electrode and electrolyte should be minimized as long as there is no electrical short across the layers. Numerous methods for fabrication of thin ceramic films have been attempted for high performance SOFCs. Physical vapor deposition (PVD) including sputtering and chemical vapor deposition (CVD) processes have been reported as successful methods for production of thin ceramic layers in several micron scales or under, accordingly SOFCs made by PVD or CVD have achieved relatively high performance [1-2]. However, most of the PVD and CVD techniques require high-cost setups including vacuum system and they are considered not suitable for production of low price materials in general. Recently, the inkjet printing technique has successfully demonstrated fabrication of thin ceramic functional films in the scale of several microns or sub-micron thickness [3-6]. The cost for film production by the inkjet printing technique is significantly lower than ones by the CVD or PVD processes. There have been several attempts to inkjet-print the SOFC components including electrolyte and cathode membranes [5-6]. Fabrication of quality cathode by the inkjet printing is especially challenging because the layer should possess a reasonable amount of micro-pores for gas diffusion but should also hold good connection of the material for ion transport. Our group has recently succeeded in fabrication of thin porous lanthanum strontium cobalt ferrite (LSCF) layers, the most popular commercial SOFC cathode material, by inkjet printing and measured reasonably high fuel cell performance i.e. the maximum power of about 400 mW cm-2 at 600 °C with open circuit voltage above 1.1 V close to the theoretical value [7]. Our experiments are conducted using a basic low-price HP inkjet printer and our results are confirmed reproducible as long as the ink source is synthesized according to our procedures [7]. This result is expected to help SOFC researchers to rapidly and easily design and prototype components in variety of patterns and material combinations. At the meeting, we will present recent progresses on our inkjet printing of ceramic fuel cell materials and discuss its applicability to fabrication of other energy devices. References [1] J.H. Shim, S. Kang, S.W. Cha, W. Lee, Y.B. Kim, J.S. Park, T.M. Gür, F.B. Prinz, C.C. Chao, J. An, J. Mater. Chem. A 1 (2013) 12695-12705. [2] H.S. Noh, K.J. Yoon, B.K. Kim, H.J. Je, H.W. Lee, J.H. Lee, J.W. Son, J. Power Sources 247 (2014) 105-111. [3] P. Calvert, Chem. Mater. 13 (2001) 3299-3305. [4] E. Özkol, J. Am. Ceram. Soc. 96 (2013) 1124-1130. [5] V. Esposito, C. Gadea, J. Hjelm, D. Marani, Q. Hu, K. Agersted, S. Ramousse, S.H. Jensen, J. Power Sources 273 (2015) 89-95. [6] C. Li, H. Chen, H. Shi, M.O. Tade, Z. Shao, J. Power Sources 273 (2015) 465-471. [7] G. D, Han, K. C. Neoh, K. Bae, H. J. Choi, S. W. Park, J.W. Son, J. H. Shim, J. Power Sources 306 (2016) 503-509.

Resume : Recently there has been tremendous research on self-assembled vertically aligned nanocomposite thin films with two immiscible components hetero-epitaxially grown on single crystal substrates [1-4]. These structures have the advantages of utilizing both component functions and tuning material properties with high interface-to-volume ratio, hetero-epitaxial strain, or cation valence state. Here we report about the characterization of self-assembled vertically aligned non-magnetic zirconium oxide (ZrO2) and ferromagnetic perovskite lanthanum strontium manganese oxide (La2/3Sr1/3MnO3, LSMO) pillar–matrix nanostructures with a film thickness of about 50 nm, which are epitaxially grown on (001) single-crystalline lanthanum aluminum oxide (LaAlO3) substrate by pulsed laser deposition. With the application of electron energy-loss spectroscopy (EELS) in a probe-aberration-corrected JEOL ARM200CF, atomic resolution elemental distribution, including La, Sr, Mn, and Zr, and the Mn valence state variation at the interface between LSMO and ZrO2 were examined. Minor amounts of Zr were found to occupy Mn positions within the matrix. The Zr concentration reaches a minimum near the pillar–matrix interface accompanied by oxygen vacancies. Substantial La and Mn diffusion into the pillar was revealed at atomic resolution and a concomitant change of the Mn valence state was observed. In addition, Mn-rich walls were found connecting adjacent pillars. The crystal lattices on either side of the wall are displaced by an anti-phase shift. The Mn valence state in the channel was found to be identical compared to the matrix. The wall plane is of {110} or {130} type. The role of the pillars and walls regarding elastic strain and local electric fields will be discussed. The spin, charge, and orbital ordering in LSMO are extremely sensitive to local structural and elemental variations. Thus, these results provide the basis for understanding the origin of the anomalous magnetic anisotropy and modifications to the electric transport properties of LSMO by introducing non-magnetic ZrO2 pillars [5]. References [1] A.P. Chen et al., Nanotechnology 22 (2011) 31 [2] A. Imai et al., ACS Nano 7 (2013) 11079 [3] H. Zheng et al. Nano Lett. 6 (2006) 1401 [4] H.J. Liu et al., ACS Nano 6 (2012) 6952 [5] D. Zhou et al., APL Materials 2 (2014) 127301 Acknowledgements The research leading to these results has received funding from the European Union Seventh Framework Program [FP/2007-2013] under grant agreement no 312483 (ESTEEM2). Financial support for the ARM200CF project by the Max Planck Society is gratefully acknowledged.

Resume : Tungsten is the plasma-facing component (PFC) material for the ITER divertor due to its high melting temperature, high thermal conductivity and low erosion yield. As a drawback, tungsten has a strong chemical affinity with oxygen and native oxide is naturally present on tungsten surfaces, which leads to the formation of oxide tungsten layers. In order to study the effect of oxidation on tungsten PFCs properties, the behavior of WO3-x layers under deuterium/helium bombardment and thermal cycling effect in divertor-like conditions, we have produced thin layers of WO3-x which mimic the possible oxidation of tungsten PFCs. The formed oxide tungsten layers were characterized using scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques. The thickness of the oxide tungsten layers, controlled using the above approaches and, were found to be in the range of 20nm - 250nm [1]. In this work, a set of virgin tungsten and oxide tungsten samples will be separately exposed to D and He plasma and/or ion beams with E=0.01-10 keV and high fluxes (1020-1024 m-2 s-1). Preliminary low energy D plasma exposure (11 eV/D+) of oxide tungsten has been performed at PIIM laboratory (Marseille-France). Due to D implantation followed by its deep diffusion [2], a phase transition in the WO3-x, change in the layer colour as well as formation of tungsten bronze (DxWO3) have been observed. Therefore, comparative study of D (high affinity to bond formation) versus He (high affinity to induce the creation of bubbles, holes and nanostructure morphology [3]) exposures is mandatory in order to determine the elementary processes of implantation and to the dissociation of chemical/physical effects. By coupling the Raman spectroscopy and SEM/AFM analysis, the process of structural damage in surface/bulk will be described.

Resume : Rare earth co-doped zinc oxide thin films have been successfully deposited on heated glass substrates using the spray pyrolysis technique. The effect of rare-earth co-doping on structural, composition, morphology, optical and electrical properties has been studied and discussed. All films are polycrystalline and exhibit hexagonal wurtzite structure with a preferential orientation along [002] direction. Optical characterization of the films shows that the films exhibit a transmittance between 65 % and 80 % in the visible range depending on the dopant element and the doping level. Photoluminescence measurements reveal the existence of various defects in our samples and show a clear luminescence band at which characterize the Yb transition between the electronic levels 2F5/2 to 2F7/2. - No emission from Tb or Er was observed in the 300-1000 nm wavelength range. The best electrical resistivity values were in 6.10-2 -5.10-2 Ohm.cm range.

Resume : This study deals with the deposition and characterization of ZnO and AZO thin films by using sol-gel deposition technique. The effect of Al doping for different Al/Zn atomic ratios (1-5%) on structural, electrical, and optical properties of ZnO thin films was determined in detail. Electrical characterization results have revealed that the lowest resistivity for the films deposited on glass substrates is obtained for the ZnO films doped with 1% Al/Zn atomic ratio, while it was 5% for the films deposited on fluorine-doped tin oxide (FTO) substrates. In addition to this, it was deduced that the best transmittance in the 300-1100 nm wavelength range was obtained for the 1% and 5% Al-doped ZnO films deposited on respective substrates, extracted from the conducted transmission measurements. For the structural characterization of the deposited films X-ray diffraction (XRD) measurements were performed. Results have shown that all the deposited ZnO/AZO thin films have hexagonal crystal structure with a strong preferential orientation either in the (0 0 2) or (101) plane directions. From the transmission and reflection measurements the optic band gaps of the deposited films were also calculated. It has been found that there is an increase in band gap with increasing the doping concentration, which was expected behavior that can be explained by Burstein-Moss effect. For the surface morphology analysis atomic force microscopy (AFM) measurements were carried out, which revealed that a dramatic change was taking place in the surface morphology following the doping ZnO films with different Al/Zn atomic concentrations. In addition to sol-gel, sputtering technique was also used for the deposition of ZnO/AZO thin films to compare their quality in terms of transmittance, resistivity and crystallinity. Fabricated ZnO thin films were also employed for the synthesis of ZnO nanowires (NWs) that can be utilized for a wide range of opto-electronic device applications, such as solar cells and photodetectors. In this study, as an application of synthesized ZnO NWs, they were used for the fabrication of SLG/ITO/ZnO-NWs/PCBM, SLG/ITO/ZnO-NWs/P3HT, SLG/ITO/ZnO-NWs/P3HT-PCBM, and SLG/ITO/ZnO-NWs/AgGaSe2 structured hybrid solar cells. Results have shown that the highest efficiency, 1. 74%, is obtained for SLG/ITO/ZnO-NWs/AgGaSe2 structured solar cells.

Resume : Powders of Cu2ZnSnS4 (CZTS) were successfully synthesized by a sol-gel method using copper (II) acetate monohydrate, zinc (II) acetatedehydrate and tin (II) chloridedehydrate as starting materials with different concentration of copper. Ethanol and 2-monoethanolamine were used as solvent and stabilizer, respectively. The powders were sulfurized in elemental sulfur vapor ambientat 560°C under Argon atmosphere. X-ray diffraction and Raman spectroscopy revealed the formation of the CZTS Kesterite structure. The morphology was examined using Transmission electron microscopy while the chemical composition was determined by energy dispersive X-ray spectroscopy.

Resume : CZTS layers were prepared onto Mo-coated glass substrates by a one step electrodeposition process in aqueous ionic solution of Cu–Zn–Sn–S alloy precursors, followed by a thermal treatment in elemental sulfur vapor ambient under Argon atmosphere. We investigated the effect of electrodeposition bath temperature in the range of 25-65°C, on crystallographic structure, morphology, composition and optical properties of electrodeposited Cu2ZnSnS4 (CZTS) thin films. X-ray diffraction and Raman spectroscopy showed that all deposited films present a Kesterite structure. Scanning electron microscopy analysis indicated that the surfaces of electrodeposited films were generally quite uniform and compact, with an appearance of small cracks which became larger when the bath temperature increased. Energy dispersive spectroscopy studies revealed the best chemical composition: Cu/(Zn+Sn) of about 0.80, being Cu-poor and Zn-rich in composition for CZTS films electrodeposited at 45°C. Photoluminescence studies were also performed. The films electrodeposited at 65°C showed two PL bands detected at 1.30 and 1.51 eV and attributed to band-to-tail (BT) and band-to-band (BB) recombination, respectively. Keywords : Kesterite, CZTS, thin films, photovoltaic, one step electrodeposition.

Resume : In thin film transistors (TFTs) a wide range of binary metal oxides, such as Al2O3, Y2O3, ZrO2, HfO2, TiO2, Nb2O5, have already been demonstrated as promising gate dielectrics with superior properties compared with SiO2. Gate dielectric materials with high dielectric constants are desirable, but the band offset condition that requires a reasonably large band gap should also be satisfied. The latter point constitutes a significant drawback when wide band gap semiconducting channels need to be employed as such dielectrics cannot possess at the same time wide band gaps and high permittivity. The obvious solution to both the low dielectric constant and narrow band gap issues could be the use of a composite dielectric material, i.e. a ternary oxide that combines wide band gap, high permittivity and low leakage current. To that end, the use of ternary oxides, such as La2O3.Al2O3[1] and Al2O3.TiO2[2]has already been reported. Here we report on the deposition and characterisation of Nb1-xAlxOy gate dielectrics as a function of the Nb to Al atomic ratio and their implementation in TFTs employing ZnO semiconducting channels. The films were deposited by spray coating at moderate substrate temperatures (< 400 oC) in air and characterised by UV-Vis, FT-IR, impedance spectroscopy, AFM, XRD and field-effect measurements. Analyses showed Nb1-xAlxOy smooth films with dielectric constant in the range between 9 and 40 and optical band gap between 6.1 eV and 4.2 eV. TFTs employing Nb1-xAlxOy dielectrics and ZnO semiconducting channels show low leakage currents (<6 nA/cm2), low subthreshold swing, high on/off current modulation ratio (>10^6) and electron mobilities in excess of 10 cm2 V−1 s−1. [1] D. Afouxenidis, R. Mazzocco, G. Vourlias, A. Krier, W. I. Milne, O. Kolosov and G. Adamopoulos, ACS Applied Materials and Interfaces, 7, 7334, 2015. [2] M. Esro, R. Mazzocco, G. Vourlias, O. Kolosov, A. Krier, W. I. Milne and G. Adamopoulos, Appl. Phys. Lett. 106, 203507, 2015.

Resume : The incorporation of nanostructured secondary phases in epitaxial YBa2Cu3O7-δ (YBCO) superconducting thin films can result in an improvement of the superconductors’ in-field performance as the nanoscale defects in the YBCO matrix can act as flux pinning centers. In this work, preformed nanocrystals are used as pinning centers hereby offering a better control and an enhanced flexibility over the final microstructural properties of the nanocomposite thin films. As a result, the introduced defects are homogeneously distributed throughout the film with sizes in the range of the superconductor’s coherence length, preventing the drastic decrease of the critical current density Jc as well as reducing its angular dependency in high magnetic fields. To achieve this, we have produced nanocomposite thin films starting from small ZrO2 nanocrystals in combination with low fluorine chemical solution deposition to understand the factors controlling the microstructure development and physical properties. By strict optimization on the processing level, we achieved nanocomposite thin films exhibiting Jc of 4-5 MA/cm² at 77 K in self-field as well as a much smoother decay of Jc as a function of magnetic field. This is reflected by a strong pinning force enhancement (up to 10 GN/m3 at 77K) and a reduced effective anisotropy compared to undoped YBCO films. This newly developed approach delivers scalable and high quality superconducting films for coated conductors throughout the energy market.

Resume : We present a study of the anisotropic direct magnetoelectric (ME) properties of bilayered composites featuring single-crystalline piezoelectric plates of LiNbO3 (LNO) possessing a bidomain structure with opposite polarization vectors (i.e. a head-to-head or tail-to-tail domain structure). Equivalent magnetic noise density measurements were performed for the composites operating under resonant conditions. The bidomain structures were obtained in the square shaped plates by “stationary external heating” and “diffusion annealing” methods. Thin foils of the highly magnetostrictive Metglas alloy were then bonded to one face of differently cut bidomain PE crystals. The studied systems have included Z-cut LNO and 127ºY-cut LNO. The anisotropic quasistatic ME coupling was generally found to be slightly larger in the bidomain samples relative to their unidomain counterparts. Large ME effects were obtained in low-frequency bending and high-frequency contour electromechanical resonance modes of the PE crystals. Of note is the fact that the contour modes were suppressed in the bidomain systems, whereas the bending modes were greatly enhanced. A ME coefficient as large as 340 V/(cm·Oe) has thus been found under bending resonance at 31 kHz, with a magnetic bias field of 16 Oe, in a 127ºY-cut LNO bidomain sample produced by diffusion annealing. Equivalent magnetic noise density measurements yielded a sensitivity of 24 pT/√Hz under such conditions. Thus, we have shown that such systems may be used in simple and sensitive low-frequency magnetic and current sensors.

Resume : In this work, we have produced YBa2Cu3O7-x (YBCO) nanocomposite thin films starting from preformed nanocrystals (PNC) in combination with fluorine-based chemical solution deposition to improve the superconductors’ in-field performance. As preformed nanocrystals, small ZrO2 and HfO2 nanocrystals (NCs) were synthesized to act as preformed nanocrystals, exhibiting a diameter between 4 - 8 nm and a narrow size distribution. These NCs can be stabilize in different types of fluorine-based YBCO precursor solutions, after a thorough analysis of the NCs’ surface chemistry, leading to highly stable nanocomposite precursors with long shelf-lives. Afterwards, the YBCO-PNC solutions were deposited on single crystal LaAlO3 substrates via both spin-coating and ink-jet printing. Nanocomposite thin films exhibiting Jc of 4-5 MA/cm² at 77 K in self-field was achieved as well as a much smoother Jc decay as a function of magnetic field. This is reflected by a strong pinning force enhancement (up to 10 GN/m³ at 77K) and a reduced effective anisotropy (γeff ~ 3) compared to undoped YBCO films. This newly developed approach delivers scalable and high quality superconducting films, capable of meeting the strict requirements for the successful implementation and distribution of coated conductors throughout energy market.

Resume : Despite the tremendous potential of all oxide thin film transistors for application in large area microelectronics further advancements have been hampered by the lack of hole transporting oxides with similar or comparable transport characteristics to their n-type counterparts. Although there are a few studies reporting p-type doping of traditional n-type oxides, the subject still remains controversial and stable p-type material has not been reproducibly observed. Hence, alternative metal oxides that show intrinsic p-type characteristics are required especially for applications in CMOS (complementary metal oxide semiconductor). There has been some success with alternative materials such as Cu2O and SnOx and indeed p-type TFTs were reported[1]. However TFTs incorporating Cu2O as a semiconducting channel suffer from a very low field effect mobility (< 10-2 cm2 V-1 s-1) making it unsuitable for CMOS applications. Additionally, these TFTs show high off-state currents that indicate the presence of a large number of copper vacancy defect states that pin the Fermi Level in the device. Here we report the fabrication of hole-transporting NiOx-based TFTs. Nickel nitrate hexahydrate and erythritol solutions in ethanol (0.2 M) were spin coated onto fused silica, c-Si, spray coated Al2O3 gate dielectrics and glass and underwent thermal annealing at different temperatures in air. Analyses revealed that at the optimum annealing temperature of about 340 oC NiOx films (80 nm) with optical band gap of about 3.6 eV and overall transmittance in the visible spectrum in excess of 75 % were produced. X-ray diffraction showed both cubic and hexagonal NiOx polycrystalline material (average crystal size of 15 nm) embedded in a dominant amorphous matrix. TFTs employing thermal evaporated gold source and drain contacts exhibit excellent hole transport characteristics with negligible hysteresis, low operating voltages (-10 V), high hole mobility in the order of 10 cm2 V−1 s−1 and high current on/off ratio of about 10^4. [1] P. Pattanasattayavong, S. Thomas, G. Adamopoulos, M. A. McLachlan and T. D. Anthopoulos, p-channel thin-film transistors based on spray-coated Cu2O films, Appl. Phys. Lett, 102, 163505, 2013

Resume : The goal of this research is to prepare titanium dioxide (TiO2) nanorods with different lengths for the construction of hybrid light-emitting and photovoltaic devices. TiO2 is rarely used for light-emitting purpose due to its white appearance and low transmittance in the visible range. In this study we prepared TiO2 nanorods via the hydrothermal methods with careful control of growth time and temperature. TiO2 nanorods with lengths from 100 to 300 nm are successfully grown upwards on FTO substrates, and the transmittance of the TiO2 nanorods reaches 80–90% from 400 to 700 nm. A series of hybrid light-emitting devices with the configuration of FTO/TiO2 nanorods/ionic PF/MEH-PPV/PEDOT/WO3/Au were fabricated and evaluated. A max brightness of 4,500 nits and current efficiency of 0.66 cd/A were achieved with 100 nm TiO2 nanorods, and the device performance was decreased with increasing nanorod length. Besides, longer TiO2 nanorods with lengths from 600 to 1000 nm were also prepared by elongating growth time. In this case, the transmittance of those TiO2 nanorods drops to 20–50% in the visible range. Inverted polymer solar cells with the configuration of FTO/TiO2 nanorods/ionic PF/DPP-PT:PCBM/PEDOT/WO3/Au were fabricated and evaluated. A max PCE value of 2.48% was obtained with 600 nm TiO2 nanorods, which was comparable with the previous results using zinc oxide (ZnO) nanorods as electron transporting layer.

Resume : The p-n junctions, consisting of p-type Pr0.7Sr0.3MnO3 (PSMO) and n-type ZnO layers, have been fabricated on Al2O3 (012) substrates by using pulsed laser deposition. The x-ray diffraction pattern of PSMO/ZnO/sapphire heterostructure implies high degree of epitaxy and good crystallinity. No secondary phase could be found. Such junctions also exhibited excellent and reproducible rectifying behaviors over the temperature range 180K-300K. By applying different magnetic fields, the junction properties can be modified significantly. The influences of optical and strain fields on the junction behaviors were also investigated. Moreover, from the photoluminescence spectra of these heterojunctions, the wavelengths were observed to shift considerably at the magnetic field of H=1T. These phenomena can be attributed to the high magnetic sensibility of PSMO, which causes the dependence of photoluminescence of the junctions on external magnetic fields

Resume : The perovskite manganite of the type La0.7Ca0.3MnO3 (LCMO) are characterized by a rich and complex phase diagram caused by the competition among spin, charge, orbital and lattice degree of freedom. These oxides have a rich and complex physics related to the large importance of electron-lattice and electron-electron interaction. In addition to the well-established devices based on the magnetic tunnel junctions (TMJ) such as read-heads of modern hard disk drives and magnetic random access memory (MRAM) of nonvolatile memory, the TMJs can be used in many systems for example as a magnetic field detector, microwave oscillator and receiver, or spin wave emitter. Depositing graphene on surfaces of mixed valence transition metal oxides is an interesting route to induce tunable interactions in graphene. The combination of correlated oxides with graphene may give rise to a wide variety of proximity phenomena with interesting implications for fundamental science and device concepts. In this study we have successfully transferred few (1-2) layers of graphene on top of epitaxial La0.7Ca0.3MnO3 (LCMO) thin films grown by metal organic deposition (MOD) process on LaAlO3 substrates. The graphene is first grown on Cu foils by chemical vapor deposition (CVD) process and then Polymer Polymethyl Methacrylate (PMMA) is deposited on the top of graphene/Cu. After dissolving the Cu in FeCl3, the graphene/PMMA is transferred on top of the epitaxial LCMO/LAO system. Finally the PMMA was dissolved in acetone at 80 degree C. Raman spectroscopy measurement confirm the success of the transfer of graphene on top of LCMO thin films having various thicknesses ranging from 20 to 100 nm. Atomic force microscopy observations, temperature dependence of resistivity and magnetizations measurements have been conducted on various Graphene/LCMO/LAO structures. Promising results are obtained making these nanocomposites promising candidates for various spintronic applications.

Resume : In order to obtain hydrophobic nanoparticles, the functionalization of inorganic nanoparticles can be achieved with organic compounds, types of the fatty acids, respectively unsaturated or/and saturated monocarboxylic acids with straight-chain and an even number of carbon atoms in molecules. The interaction between the surface of inorganic nanoparticles and agents occurs through hydrophobic part by the carboxyl functional group (-COOH). The purpose of this paper was to obtain functionalized ZnO nanoparticles using oleic acid (C18H34O2) and stearic acid (C18H36O2) as compatibilizer agents. Also, the compatibilizer action was determined by the capacity and high affinity to the attachment / chemical bonding by functional groups on the metal oxide nanoparticles surface. For both types of compatibilizing agents have been kept the same optimum process conditions, magnetic stirring for 3 hours and the temperature 60 °C and sonication for 30 min. The structure and morphology of the functionalized ZnO nanoparticles (ZnO-oleic acid and ZnO-stearic acid) were investigated using Fourier transform infrared spectrometry (FT - IR), field emission scanning electron microscopy (SEM) and X-ray diffraction (XRD). The results indicated that the agents interact with the nanoparticle surface to form a monolayer of fatty acid to the surface of ZnO. SEM analysis showed the influence of agents on particle morphology, and XRD diffraction patterns confirmed that the agents do not influence the crystal structure of samples, not identified their characteristic peaks.

Resume : In recent years, the need for smart window materials that lower the energy consumption for heating, venting and air-conditioning of buildings has grown immensely. These smart materials undergo a reversible change in physical properties depending on various conditions. A material that fits this description is vanadium dioxide, a thermochromic material that changes from a monoclinic to a rutile phase when heated above a critical temperature. This metal-insulator transition (MIT) leads to the absorption of infrared radiation. By absorbing this, a lower amount of heating-up occurs inside buildings and less cooling is needed. During this work, the main focus is the development of novel and easy methods to synthesize thermochromically active vanadium dioxide nanoparticles. Solvothermal and microwave syntheses were performed and optimized. The influence of various reaction parameters on the morphology, crystal structure and thermochromic properties of the nanosized materials was studied.

Resume : Zinc oxide (ZnO) is a direct-gap semiconductor with the band gap about 3.3 eV and ZnO-based nanostuctures are known to be promising functional materials with a wide range of applications in gas sensors, light emitting diodes and lasers. It is known that ytterbium (Yb) ions incorporated in semiconductor and dielectric matrices can lead to an appearance of the sharp luminescence band at 980-1000 nm. Nanoparticles and nanocomposites based on ZnO:Yb are promising to create thin layer convertors of the solar spectrum to longer wavelength region that can be used to improve the efficiency of solar cells. In the present work we prepare ZnO /Yb2O3 nanocomposite powders by wet chemistry methods followed by thermal annealing in air up to 750 C. The synthesis was carried out from alcohol solutions with Yb atomic content up to 6%. The dried samples consisted of 20-200 nm sized ZnO nanocrystals decorated by smaller Yb2O3 nanocrystals. The dried powders were investigated at room temperature by using x-ray diffraction, transmission electron microscopy and photoluminescence (PL) spectroscopy under excitation with visible and ultraviolet light sources. The PL spectroscopy showed sharp peak of the Yb ion emission in the spectral region of 980-1050 nm. While the PL intensity depended weakly on the Yb content, it was stronger for the samples annealed at 750 C. The obtained results are explained by considering the excitation of Yb ions by an energy transfer from the photoexcited ZnO nanocrystals. The prepared nanocomposites can be interesting for applications of ZnO-based nanostructures in light emitting optoelectronic devices and solar cell coatings.

Resume : The efficient integration of ZnO nanowires (NWs) into various electronic, optoelectronic, and photovoltaic devices strongly relies on the ability to control their structural uniformity in terms of position, length, diameter, vertical alignment, and period as well as their polarity [1]. By combining selective area growth, using ZnO single crystals pre-patterned by electron beam lithography (EBL) and chemical bath deposition (CBD), we demonstrate the formation of dense arrays of ZnO NWs with a high structural and optical quality [2]. The O- or Zn-polarity of ZnO NWs is controlled by employing O- and Zn-polar ZnO single crystals, respectively. Their physical properties are revealed by a large number of characterization techniques including transmission electron microscopy and cathodoluminescence. Alternatively to the expensive and time consuming EBL, cost-efficient and surface scalable techniques for the selective area growth of ZnO NWs are also developed. Nanoimprint lithography is used to pattern ZnO seed layers deposited either by dip coating [3] or by MOCVD. The subsequent growth by CBD reveals the possibility to form ZnO NW arrays with good vertical alignment and morphology. These findings open the way to the fabrication of high quality ordered ZnO NW heterostructures for nanoscale devices. [1] J. Michallon et al., Optics Express 22, A1174 (2014). [2] V. Consonni et al., ACS Nano 8, 4761 (2014). [3] S. Guillemin et al., The Journal of Physical Chemistry C 119, 21694 (2015).

Resume : Generating the white light in an LED is based on the use of the different types of phosphors having the ability for the conversion of the light emitted by blue chips or UV. The use of phosphors as YAG:Ce type has caused numerous controversies, but there are a lot of studies completed in a satisfactory manner for their application on an industrial scale. To white LED manufacturing the highest unknown still remain the phosphor deposition on the chips. The quality of light emitted by a white LED is strongly influenced by the phosphor composition, (co)dopant concentration, average grain size, phase purity, the dispersion medium, the degree of dispersion of the phosphor in the matrix, coating uniformity, concentration and thickness of the applied layer. In the present paper is presented the nanocomposite synthesis by incorporation of YAG:Ce phosphor nanoparticles into a Poly(vinylidene fluoride) (PVDF) matrix in presence of N-Methyl-2-pyrrolidone (NMP). Phase evolution of the product was performed by X-ray diffraction and bond configuration was identified by vibrational spectrometry. Study of the morphology and microstructure were performed by field emission scanning electron microscopy and the luminescent properties were analysed by fluorescence spectroscopy. The results showed a good dispersion in PVDF matrix without structural modification of YAG:Ce in the composite.

Resume : Hybrid strategy of Sn-doped In2O3 (ITO) with graphene has been attempted, and various synergistic properties have been demonstrated in ITO-graphene hybrid nanostructures due to the advantageous effects of interface modification on the charge transport process. These properties were critically determined by charge transfer process between ITO and graphene in the hybrid materials. Therefore, understanding the charge transport properties in the ITO-graphene hybrid system is greatly significant. In this work, we report the effects of interface control using reduced graphene oxide (RGO) on the charge transport in ITO nanocomposites. The ITO-RGO nanocomposites were fabricated by the consolidation of RGO coated ITO nanoparticles. Charge transport properties in the nanocomposites were characterized based on the four-point probe method. Compared with ITO nanocomposite without RGO, the ITO-RGO nanocomposites show the enhanced mobility with increased carrier concentration. Schottky barrier at the grain boundaries could be suppressed through interface control using RGO. This leads to single crystal-like charge transport behavior in the ITO-RGO nanocomposites. Detailed mechanism for the enhanced charge transport properties in the nanocomposites will be presented.

Resume : In this study, we have investigated effects of self-textured (S-T) AZO anode on efficiency of green emission OLEDs. S-T AZO layer has been prepared on glass substrates by DC magnetron sputtering technology. Wrinkle structures were observed from the surface of S-T AZO layer which is suitable for internal out-coupling efficiency enhancement layer. The large grain size of ~㎛ was formed with the roughness of 20nm. The sheet resistance and transmittance were measured to be 7.1ohm/sq. and 87%, respectively, which is comparable to those of ITO anode layer. The main advantage of our approach is internal out-coupling layer can be formed during transparent conducting oxide anode layer preparation without additional process, for example, film lamination. Moreover, S-T AZO layer can replace conventionally used ITO anode without degradation of its electrical and optical properties. Based on S-T AZO anode, green emission OLEDs devices were fabricated and typical optical and electrical properties were characterized. For comparison, reference OLEDs with ITO anode were also fabricated and characterized. The power efficiency of green emission OLEDs was measured to be 39 lm/W whereas that obtained from reference OLEDs was 27 lm/W. The power efficiency of OLEDs based on S-T AZO was increased about 40% compared with reference OLEDs. The increase of power efficiency was originated from the extraction of light from the substrate mode confined in substrate by enhancing scattering. Furthermore, turn-on voltage was slightly decreased from 4.0V to 3.8V. Our study opens up the possibility of increasing power efficiency of OLEDs devices without any additional process for low production cost process.

Resume : Transparent conductive electrode films, which shows low sheet resistance and high transparency have been attracted much attention because of their potential for use in optoelectronic devices applications, such as smart window, photovoltaic cells and flat panel displays. Multilayer transparent electrodes were prepared by using RF/DC magnetron sputtering system on glass substrates. The sandwich type multilayer structure consists of NiInZnO/Ag/NiInZnO(NIZO/Ag/NIZO). The optical and electrical characteristics of multilayer structures of NIZO/Ag/NIZO have been investigated as a function of the thickness of Ag and NIZO layer. Sheet resistance of 9.8 Ω/□ was obtained from the 8 nm thick Ag layer, which is much lower than that of conventionally used multilayer electrodes. In this case, the thickness of NIZO/Ag/NIZO layer was fixed to 150 nm. Also from the same thickness Ag and NIZO high transparency of 93% was achieved in visible wavelength range. Therefore, it can be concluded that the electrical and optical properties of NIZO/Ag/NIZO films were dominantly dependent on the thickness of the Ag layer. Overall, the properties of the NIZO/Ag/NIZO film were comparable or superior to those of the other TCO films such as InSnO(ITO) and InZnO(IZO). The deposited NIZO/Ag/NIZO films were applied to fabricate polymer dispersed liquid crystal (PDLC)-based smart windows. The NIZO/Ag/NIZO multi-layer-based smart windows exhibited lower operating voltage and higher cutoff rate of infrared light compared with those of ITO-based smart windows.

Resume : We present the fabrication of TiO2/NiO composite nanofibers by a simple electrospinning process by controlling various atomic ratios of Ti and Ni contents with mixed titanium precursor and nickel precursor solutions. The morphology and crystal structure of the samples were carefully characterized with field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Results show that the electrospun nanofibers consisting of titania and nickel(Ⅱ) oxide are uniformly formed so that it is expect that composite nanofibers could be extended to apply for photocatalysts. Due to p-n junction generated by n-type TiO2 and p-type NiO, it is looking forward to showing a great efficiency.

Resume : We synthesized IrO2 and TiO2 mixed nanofibers via electrospinning process. The morphology and crystal structure of the samples were characterized with field emission scanning electron microscope (FE-SEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Because of the property of IrO2 in electrochemical reaction, IrO2 and TiO2 mixed nanofibers are also electrochemically active. Moreover, these nanofibers have an advantage in water splitting. Water is separated into oxygen and hydrogen when chemical reaction occurs. Even though TiO2 has no influence in electrochemical reaction, our result shows that the potential in hydrogen evolution reaction (HER) is lower than existing common materials.

Resume : Flexible transparent electrodes are essential components for flexible optoelectronic devices, such as touch panels, organic light-emitting diodes, and solar cells. Indium tin oxide (ITO) is widely used as transparent electrode in optoelectronic devices. However, ITO has certain problems, mainly centered on its scarcity of supply, and its ceramic nature. Therefore, alternative transparent electrodes with excellent optical, electrical performance and mechanical flexibility will be greatly demanded[1-2]. Recently ZnO, possible to process in low temperature condition and have fast electron mobility, is received attention for material used in the flexible electronic devices. ZnO, representative II-VI oxide semiconductor, is chemically stable material having high exciton energy and comparatively wide band gap energy. The substitution of Zn2+ ions with group III ions (B3+, Al3+, Ga3+, and In3+) generates extra electrons and improves ZnO optical, electrical, thermal, and magnetic properties. And Al3+ has been the most used dopant element due to its small ionic radius and low material cost. So, we grew up AZO nanorods on PET substrate for flexible transparent electrodes by hydrothermal methods. And we used UV-visible spectrometer for analyzing the optical characteristics of AZO nanorods. As the result of UV-visible spectrometer, Al-doped ZnO nanorods exhibited excellent transmittance of 80% or more at 400 ~ 800 nm in the visible light region. Because of the high composition ratio, we confirmed that the optical absorption was less caused. Acknowledgements This research was supported by National Research Foundation of Korea (NRF) grant by the Korea Government. References [1] Li, G. et al. High-efficiency solution processible polymer photovoltaic cells by self-organization of polymer blends. Nature Mater.4, 864–868 (2005). [2] J. Fenn , “If not ITO, then what?” presented at Soc. Vac. Coat. , (2010).

Resume : Epitaxial thin films of functional oxides were synthesized by a polymer assisted chemical deposition method, based on aqueous polymeric/metal solutions. In this process, polymer controls the viscosity and binds metal ions, resulting in a homogeneous distribution of metal precursors in the solution. Thermal treatment removes both water and polymer at low temperatures (450 ? 500 oC), and further annealing yields epitaxial crack-free films. The successful preparation of these films with stable solution offers unique advantages on thickness control and composition uniformity over large areas compared to other solution-based techniques. Epitaxial thin films of rare-earth manganites, RE1-xMxMnO3 (RE=rare earth, M = Ca, Sr or Ba), with mixed-valence and perovskite structure, and perovskite rare earth nickelates (RENiO3) were synthesized by this method. The structural, transport and magnetic properties of these films were investigated as a function of the processing conditions, the thickness of the films and the single crystalline substrate used. The magnetic and metal-insulator (MI) transition temperatures were determined, and the magnetic coupling across the nickelate-manganite interface will be analyzed. Financial support from Spanish MINECO project MAT2014-51778-C2-1-R is acknowledged

Resume : Titania nanostructures are successfully used in hybrid solar cells. Tailoring of the titania nanostructures is achieved by a block copolymer assisted sol-gel synthesis. Different morphologies are installed by the choice of the weight ratios used in the sol-gel synthesis. In particular porous nanostructures are of interest, with pore sizes of several tens of nanometers. Such foam-like titania films have high mechanical stability and provide a percolating network for charge transport. Complex functional stacks are build-up by combining porous films with for example disc-shaped titania nanoparticles. Moreover, hierarchical titania foams are realized by a combination of polymer / colloidal tempating and artificial structuring is demonstrated via combining nano imprint lithography with block copolymer assisted sol-gel templating.

Resume : Nanorices fluorine doped tin oxide (nr-FTO) was successfully synthesized using only FTO substrate in hydrothermal process. This method combining with novel recipe of hydrothermal solution managed to synthesis homogenous film of nr- FTO and spherical nr-FTO. The samples were characterized using FESEM, EDS, XRD and solar simulator measurements. The FESEM results show the grain size of FTO nanorice which is 54.8nm along with diameter of 21.0nm. Nanorices fluorine doped tin oxide were prepared at 5 h, 10 h, 15 h and 20 h, respectively. Finally, power conversion efficiency of Dye-Sensitized solar cell were measured and 2.77% was the highest which was prepared at 10 h of hydrothermal process.

Resume : The Advanced Oxidation Process (AOPs) allow the elimination of pollutants resistant to other conventional treatments. Photocatalysis plays a central role in these treatments because of its capacity to produce hydroxyl radicals, with an oxidizing power significantly higher than conventional oxidants. The photoelectric charge generation appears to be the key step in the photocatalytic process. While the implementation of photocatalytic tests is cumbersome and expensive, a simple procedure based on the photoelectric activity evaluation of oxides, without any implementation of catalytic tests, appears to be a time- and cost-effective approach to achieve a first selection between candidate materials. The primary objective of this study was the synthesis of morphology-controlled hematite particles. The selected morphologies were ellipsoids, platelets, dendrites, and pseudocubes. In the case of the ellispoids, the use of phosphate additives allowed a precise control of the particle aspect ratio. The second objective of the study was to design, implement and validate a protocol for characterizing the photoelectric activity of an oxide. The selected device is an adaptation of solar cell devices. The original idea is to consider the photovoltaic effect as a signature of the photoelectric activity of the material. The device was used with all synthesized particle morphologies, and revealed a significant shape effect on the particle response to light.

Resume : Polymer solar cells (PSCs) have attracted high attention over the last decade due to their unique advantages of low-cost production, environmentally sustainability, mechanical flexibility and light weight. Interfacial layers (IL) are important components of high efficient organic solar cells as they provide efficient charge carrier extraction towards the electrodes avoiding hereby losses such as non-Ohmic contact, charge carrier recombination and exciton quenching at the interfaces.[1] In the past, solution processed materials such as metal oxides have been successfully introduced as hole and electron blocking layers for organic solar cells. Especially ZnO based electron extraction layers are nowadays one of the most promising IL systems leading to efficiencies of 10.3% in single junction devices.[2] Beside their electronic properties, such metal oxide layers introduce so-called optical spacer (OSP) effects that modify the light distribution inside the solar cell using regular device structures.[3] We could recently demonstrate that optimization of optical, morphological and electronic properties of ZnO OSPs is necessary to reach high efficiencies in PSCs.[4] Although metal-oxide-based OSPs are applied to organic solar cells for a decade, their low conductivity limited their thickness to tenth of nanometers and thus their compatibility with robust solution processing. In order to improve the electric properties of such metal oxide OSP, techniques to improve their conduction properties are needed. Here, we present the synthesis of novel Aluminum-doped ZnO (AZO) nanocrystals (NCs) that allows fabricating high-efficiency solar cells using thick optical spacers with low temperature processing. The synthesis and detailed analysis of AZO NCs are reported followed by the fabrication of cluster-free NCs solutions in isopropanol by using ethanolamine (EA) as surfactant. The novel AZO NCs are processed into thick highly conductive optical spacers with very low film roughness at low temperature and are thus compatible with processing of highly efficient polymer solar cells using normal device structures. In order to investigate AZO OSP layers in polymer solar cells, we combined optical modeling, UV-Vis absorption spectroscopy, current-voltage analysis, external and internal quantum efficiency, transient open circuit voltage decay, impedance measurements and atomic force microscopy analysis. Furthermore the solution processing and corresponding optical and electrical properties of the AZO layers were studied in polymer solar using polymer blends based on low PTB7[5] associated with PC70BM as the acceptor material. In order to demonstrate the potential of novel AZO- based optical spacers for robust solar cell processing using thick layers, we also focused on processing of efficient PTB7:PC70BM blend layers with thicknesses up to 210 nm. Indeed, we show that AZO-based optical spacers with thickness up to 100 nm leads to solar cells with conversion efficiency up to 7.6% when combined with photoactive layer of 200 nm thickness, both enhancing strongly the robustness of device processing. More importantly, we could show for the first time that the novel AZO-based optical spacers allow color tuning of organic solar cells over a large range by varying the thicknesses of both optical spacer and polymer blends, opening new opportunities for the use of optical spacer in organic photovoltaic.[6] REFERENCES: [1] XU, C. Z., HONG, Z., YANG, Y., J. Mater, Chem. 2010, 20, 2575. [2] LIAO, S.-H., JHUO, H.-I., YEH, P.-N., CHENG, Y. S., LI, Y.-L., LEE, Y.-H., SHARMA, S., CHEN. S.-A. Scientific Report, DOI: 10.1038/srep06813 [3] a) J. Y. Kim, S. H. Kim, H. H. Lee, K. Lee, W. Ma, X. Gong, A. J. Heeger, Adv. Mater. 2006, 18, 572; b) J. Gilot, I. Barbu, M. M. Wienk, R. A. J. Janssen, Appl. Phys. Lett. 2007, 91, 113520; c) A. K. K. Kyaw, D. H. Wang, D. Wynands, J. Zhang, T. Q. Nguyen, G. C. Bazan, A. J. Heeger, Nano Lett. 2013, 13, 3796. [4] BEN DKHIL, S. DUCHE, D. GACEUR M., THAKUR, A., ABOURA, F. B., ESCOUBAS, L., SIMON, J.-J., GUERRERO, A., BISQUERT J., GARCIA_BELMONTE, G., BAO, Q., FAHLMAN, M., VIDEOT-ACKERMANN, C., ACKERMANN, J., Adv. En. Mat., 2014, 4, 1400805. [5] HE, Z., ZHONG, C., SU, S., XU, M., WU, H., CAO Y., Nat. Photonics, 2012, 6, 591. [6] GACEUR M , BEN DKHIL, S., DUCHE, D. , BENCHEIKH, F., SIMON, J.J., ESCOUBAS, L., MANSOUR, M., GUERRERO, A., GARCIA_BELMONTE, G., LIU, X., FAHLMAN, M., DACHRAOUI, W., DIALLO, A. K. VIDEOT-ACKERMANN, C., MARGEAT, O., ACKERMANN, J., Adv. Funct. Mater., 2016, 26, 243.

Resume : ZnO/graphene composite as an anode for lithium ion batteries was synthesized by a sol-gel method. Sample’s structure and morphology were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA), scanning electron spectroscopy (SEM), and transmission electron microscopy (TEM). Characterization results show spherical ZnO particles with around 30-40 nm size homogeneously inserted on graphene. Electrochemical properties were investigated by galvanostatic discharge-charge tests. ZnO/graphene composite show an initial discharge and charge capacities of 1414 mAh/g and 858 mAh/g respectively at C/20 rate and exhibits an obviously improved cycling stability compared to bare sol gel ZnO due of conducting effects of the incorporated graphene. Furthermore, results showed better electrochemical behavior compared to ZnO/graphene composite prepared by hydrothermal method with the same proportions [1]. The battery performance result indicates that the presence of graphene sheets in the composites effectively enhance the conductivity and accommodate the volume change. [1] Int. J. Electrochem. Sci., 7 (2012) 2164 - 2174

Resume : The synthesis of multi-component materials by solution-based techniques remains a challenging task due to the limited spatial control of the different species in the final material. This is especially true for mixed oxides and metal-doped materials that are relevant for many applications, including materials such as filters, sorption media or photocatalysts, for medical, electrochemical or optical applications.[1] Mixed oxides are of special interest for several reasons: the chemical properties of an otherwise “inert” support can be improved by the second component, i.e. comprising characteristics, such as higher acidity, larger surface areas, thermal stability, etc. However, the properties of the final material strongly depend on the chemical homogeneity or degree of demixing of the various components. The development of general, cost-effective of routes allowing for the synthesis such mixed metal oxides with deliberately designed structural features on all length scales (from the atomic level to the macroscopic morphology) is still a demanding task. In this presentation, we will present solution-based chemical approaches, e.g. sol-gel processes, based on single-source precursors to porous mixed metal oxide materials (coatings, bulk materials). Special emphasis is given to the sol-gel chemistry of carboxylic acid- and acetylacetone-functionalized silanes with and without the presence of a coordinated metal centre, such as europium, titanium, etc.[2-4] [1] A. Feinle, N. Hüsing, J. Supercritical Fluids, 2015, 106, 2-8. [2] A. Feinle, S. Flaig, M. Puchberger, U. Schubert, N. Hüsing, Chem. Commun. 2015, 51, 2339-2341. [3] S. Flaig, J. Akbarzahdeh, P. Dolcet, S. Gross, H. Peterlik, N. Hüsing Chem. Europ. J. 2014, 20, 17409-17419. [4] A. Feinle, F. Lavoie-Cardinal, J. Akbarzadeh, H. Peterlik, M. Adlung, C. Wickleder, N. Hüsing, Chem. Mater. 2012, 24, 3674-1683.

Resume : Mesoporous oxide films with nanoparticles inclusions have improved photocatalytic properties due to a controlled porosity and presence of light absorbing metallic catalyzers, but the exact mechanism of improvement is yet to be clarified as several phenomenons occurs concomitantly like charge carrier, surface catalysis, plasmon enhancement, and exciton relaxation. We studied nanostructured electrodes made of metallic nanoparticles (Au, Ag) inside a semi-conductor oxide (TiO2/Fe2O3) with a control of porosity and particle dispersion as an improved photocatalytic system. We performed electrochemical experiments under various ranges of light irradiation, from UV to visible, to determine the variations of redox potentials and photocurrent and thus getting some insights on the photochemical mechanism and the influence of material structure on photocatalytic properties. Porosity is introduced by using block copolymer self assembly process and the nanoparticles are grown using a salt impregnation strategy followed by reduction of the metallic salt inside the porous oxide matrix. Once electrodes are realized, they are fully characterized by SEM, TEM, XRD, UV-visible spectroscopy, and profilometry. The electrochemical properties and photocatalytic performances are then studied in a three-electrode configuration photoelectrochemical cell in order to determine the exact influence of nanoparticles as a catalyzer or as a photonic enhancer through plasmon absorption.

Resume : The design of mesoporous conducting metal oxide electrodes containing evenly dispersed and homogeneously sized catalytically active metal nanoparticles is a crucial issue in electrocatalysis. Achieving simultaneous control of the activity defining parameters such as type of porous structure, nanoparticle size, dispersion and accessibility in one go is however challenging and demands the development of new synthetic approaches. In this context, we developed a simple solution based approach, i.e. Hydrophobic Nanoreactor Templating, which allows the one-pot synthesis of various mesoporous metal-metal oxide nanocomposites [1,2] with controlled metal- and metal oxide nanostructures. Hydrophobic nanoreactor templating thereby relies on the compartmented structure of inverse polymer micelles, serving both as metal and metal oxide precursor reservoir. As exemplified for Au – tin-rich ITO nanocomposites both the overall metal-metal oxide morphology (ranging from open porous structures with one metal particle per pore to complex yolk@shell nanostructures) as well as the metal nanoparticle size and number per pore can easily be tuned by the precursor chemistry. In Line with various characterizations, material templating and formation will be discussed and high activity for electrocatalytic CO- and alcohol-oxidation demonstrated. Finally, the applicability of this approach to other functional metal-metal oxide nanostructures relevant for electrochemical energy conversion will be presented. [1] A. Guiet, T. Reier, N. Heidary, D. Felkel, B. Johnson, U. Vainio, H. Schlaad, Y. Aksu, M. Driess, P. Strasser, A. Thomas, J. Polte, A. Fischer*, Chem. Mater. 2013, 25, 4645. [2] A. Guiet, C. Göbel, K. Klingan, M. Lublow, T. Reier, U. Vainio, R. Kraehnert, H. Schlaad, P. Strasser, I. Zaharieva, H. Dau, M. Driess, J. Polte, A. Fischer*, Adv. Funct. Mater. 2015, 25, 39, 6228.

Resume : Mesostructured mixed-metal oxide thin films have received much attention in recent years. This is due, in part, because many such materials have been shown to have unique properties. The synthesis of ternary or even more complex oxides in the form of thin films with different pore structures and ordering lengths has become possible through advances in polymer templating over the past years. However, despite the progress made so far, they often exhibit an ill-defined mesoporous morphology after crystallization when prepared using commercially available polymer structure-directing agents. Here, we describe the evaporation-induced self-assembly synthesis of highly crystalline, cubic mesoporous mixed-metal oxide thin films with >15 nm pores from common sol-gel precursors and a tailor-made polyisobutylene-block-poly(ethylene oxide) diblock copolymer. We focus both on perovskite-type La1?xMexMnO3 (Me = Sr, Ca) and spinel-type LiFe5O8. For the former materials, we show that by electrochemical double layer charging ? equivalent to charge carrier density modulation ? the magnetization can be manipulated in a reversible fashion. Magnetization modulations of up to 10% have been achieved, the highest values thus far reported for electrolyte-gated mixed-valence manganese oxides. In the case of LiFe5O8, we show that the magnetization can be tuned by topotactic insertion/extraction of Li-ions. Overall, both processes allow for reversible control over magnetization and strongly benefit from the high surface-to-volume ratio of the sol-gel derived materials.

Resume : The CuO/TiO2 interphase is receiving attention because of its possible applications in photovoltaic devices. In this work we analyze thin films obtained by mixing TiO2 nanocrystalline powder with CuO nanopowder. Samples with mass concentrations from 5 to 10% of CuO in TiO2 were prepared from a colloidal suspension using “doctor blade” technique. Heat treatment (500°C, 1h) was used to provoke crystals necking and better adhesion to substrates. XRD analysis indicate that no preferred orientation resulted. Samples diffuse light strongly. Therefore, light reflection decreases radiation possibility to create electron-hole pairs. Since TiO2 does not absorb light in the spectral range where the CuO absorption edge is located, it was possible to obtain the CuO absorption coefficient spectra and then find the bandgap energy. Obtained values are compared to disagreeing reports in the literature regarding value and bandgap nature. SEM images show a mesoporous structure for all samples. Short-circuit photocurrent direction and open-circuit photovoltage obtained using λ=565 nm green monochromatic light confirm that the CuO injects electrons to the TiO2. This is explained in relation with literature reports regarding relative conduction band position and mechanisms occurring in CuO/TiO2 interface when excited by visible/UV radiation. These values also indicate big losses through recombination due to not small enough nanocrystal size to avoid bulk recombination or to surface defects.

Resume : In this talk I will review our most important results about the physical properties of high-quality epitaxial oxide thin-films prepared by a chemical solution method. In the first part of the talk I will describe our efforts for identifying the most relevant chemical aspects of the synthesis, and the strategies we followed for optimizing them. After that, I will discuss several examples to demonstrate that an excellent control over the thickness, chemical, structural, electronic and magnetic homogeneity can be achieved on multicationic oxides, over areas of several cm2 by this simple method. I will show that epitaxial oxide-heterostructures can be also prepared in this way, which constitutes an important step forward in the competitiveness of the chemical solution methods, compared with traditional physical deposition techniques. Finally, I will describe our attempts to combine this chemical solution technique with physical deposition methods (in this case MBE) for the synthesis of complex heterostructures on Silicon. Particularly, I will show how a large piezoelectric response can be obtained in relatively thick layers of BaTiO3, deposited over porous chemically-synthesized layers of LSMO, on STO/Si.

Resume : Highly oriented and epitaxial lead-free piezoelectric (Na0.5K0.5)NbO3 (KNN) thin films were fabricated on (100)-, (110)- and (111)-oriented SrTiO3 substrates by a simple and environmental friendly chemical solution deposition. The aqueous KNN precursor solution was prepared from soluble alkali-precursors and Nb-ammonium oxalate. The stable precursor solution was deposited onto SrTiO3/Nb:SrTiO3 substrates by spin coating. To aid texturing of the KNN-based films, a molten salt dissolution/reprecipitaion method was used and NaCl/KCl was added to the precursor solution. Homogeneous films with an average grain size of 60 nm were prepared after heat treatment at in the temperature range 7-900 oC. The prepared films were highly oriented following the orientation of the substrates. An epitaxial layer starting from the film-substrate interface was observed for the (100)- and (110)-oriented films followed by a textured polycrystalline layer in the upper part of the films. Local piezoelectric properties showed highly ferroelectric properties. The piezo- and dielectric properties will be discussed in relation to the texture, epitaxy and orientation of the substrate.

Resume : We report on the fabrication by all-chemical deposition method of highly textured YBa2Cu3O7-x (YBCO) films using a 10 mol % Gd-doped CeO2 (CGO) capping layer deposited by the new polymer assisted deposition (PAD) technique on top of yttria stabilized zirconia (YSZ) buffered stainless steel substrates by alternating beam assisted deposition (ABAD) (ABADYSZ/SS). PAD utilizes an aqueous polymer to bind metals in a complex that serves both to encapsulate the metals, in order to prevent chemical reaction and to maintain an even distribution of the metal in the solution. The main advantage of PAD technique is the very long stability of the precursor solution (years- essential for the scalability process) and it is environmentally friendly. An optimization study of the epitaxial growth of the PAD-CGO buffer layer on ABADYSZ/SS for the fabrication of coated conductors is presented. Structural and morphological properties were investigated by X-ray diffraction (XRD) and atomic force microscopy. It has been demonstrated the efficiency of the PAD-CGO buffer layers for the growth of epitaxial YBCO from low-fluorine solution. The CSDYBCO/ PADCGO/ABADYSZ/SS architecture was characterized by XRD and SEM analyses. Tc values of 91.1 K and Jc at 77K of 1 MA/cm2 were obtained. Acknowledgement The research leading to these results has received funding from the European Union Seventh Framework Programme [FP7/2007- 2013] EUROTAPES under grant agreement n° NMP-LA-2012-280432.

Resume : We demonstrate solution-processed zinc-tin oxide high-voltage thin film transistors (HVTFT) operating at 1kV to enable driving arrays of dielectric elastomer actuators (DEA). DEAs, typically driven at voltages over 1kV, find applications where their flexibility and high strain (>50%) provide unique advantages, such as in soft robotic, tunable optics, and haptic interfaces. The semiconducting zinc tin oxide film was synthesized through a sol-gel process and applied by spin coating or inkjet printing on a polyimide substrate. Material formulation, synthesis conditions (annealing temperature, time and atmosphere) and substrate passivation were identified as parameters having a strong influence on the transistors characteristics at high voltage. To operate at very high voltage, offsetting the gate from the drain, high-breakdown field and thick gate dielectrics were implemented. Our metal-oxide TFTs exhibit an on-off current ratio of 100 and a positive threshold voltage of 20V at 1 kV, an operating voltage outperforming the results achieved until now for HVTFT made of silicon and organic channels. The TFTs characteristics, stability and high-voltage artifacts will be discussed with respect to the semiconductor preparation parameters and their architecture. Optimized HVTFTs were successfully applied to the switching of DEAs at 800V.

Resume : Silicon dioxide is the most widely used dielectric material for optical and electronic applications. Production of SiO2 has been achieved by thermal oxidation of silicon, plasma enhanced chemical vapour deposition, sputtering, electron beam evaporation, atomic layer deposition etc. The conventional production of SiO2 by thermal oxidation by necessity requires the use of Si as the substrate and the other methods either produce low quality/poor interface material and/or require high deposition temperatures. Here, we report on the deposition and characterisation of SiO2 gate dielectrics grown by spray coating in air at moderate temperatures i.e. 350 oC from SiCl4 solutions in pentane-2,4-dione (0.1 M). SiO2 films on ITO were investigated by means of x-ray diffraction, XPS, UFM/AFM, admittance spectroscopy, UV–Vis absorption spectroscopy, spectroscopic ellipsometry, and field-effect measurements. Analyses of spray coated films reveal smooth films (RRMS<1 nm) of amorphous phase with dielectric constant of 3.8, optical band gap of 8.1 eV (by extrapolation) and leakage currents of 10-7 A/cm2 at 1 MV/cm. XPS measurements further confirm SiO2 structures and FTIR spectra show features related to SiO2 only. Thin film transistors based on thermally grown C60 and pentacene semiconducting channels employing both spray coated as well as thermally grown SiO2 gate dielectrics exhibit identical transport characteristics in terms of hysteresis, leakage currents, carrier mobility and on/off current modulation ratio.

Resume : In the past few years, titanium dioxide with different morphologies have been extensively applied in photovoltaic devices, such as dye-sensitized and perovskite solar cells. In contrast, nanostructured zinc oxide (ZnO) is less reported in the area of photovoltaics and solar energy. In this study, we aim to prepare ZnO nanorod arrays by the hydrothermal method for the construction of perovskite solar cells. By careful control of growth time at low temperature ~65oC, vertically grown ZnO nanorod arrays with length of 300 nm on ITO substrates were obtained, as observed by SEM and AFM. Besides, high transmittance up to 90% in the visible range also promotes ZnO nanorods for lighting and energy harvesting applications. Regular-type perovskite solar cells with the configuration of ITO/ZnO nanorods/PCBM/CH3NH3PbI3/P3HT/WO3/Au were fabricated and evaluated. The perovskite film CH3NH3PbI3 was prepared via the two-step spin-coating process. Moreover, non-doped ZnO nanorods/PCBM and P3HT/WO3 (instead of expensive Spiro-OMeTAD) were used as electron and hole transporting layers, respectively. All devices were measured in the ambient environment without encapsulation under standard AM1.5G illumination condition. The best device showed an open-circuit voltage (VOC) of 0.9 V, a short-circuit current (JSC) of 20.92 mA/cm2, a fill factor (FF) of 54%, and power conversion efficiency (PCE) of 10.2%.

Resume : Ferroelectrics (FEs) are a class of materials that show a spontaneous polarization switchable by an external applied voltage. An outstanding feature of these compounds is that under illumination they can develop an open circuit voltage much higher than the bandgap of the materials themself, making them attractive for photovoltaic application. One of the main issues related to FEs is their high bandgap (usually >3eV) mostly due to the transition metal-oxygen bonds and the large difference in electronegativity between the elements. Recent investigations concern the development of new FE materials with lower bandgap using low-cost techniques , in order to obtain a commercially competitive PV device. In this work, we present the structural, optical and electrical properties of BiMnxOy (BMO) oxide materials produced by the sol-gel technique. The X-ray diffraction analysis demonstrates a good grade of crystallization versus the sintering temperature. The materials are found to absorb in the UV to visible wavelength range. The ferroelectricity of the samples i salso investigated. The best materials are integrated in ferroelectric based solar cells and the extracted photovoltaic parameters will be discussed

Resume : We present the co-decoration of RuO2 and metallic Ru nanoparticles on TiO2 nanobelts through solution impregnation and reduction with post annealing. The spectroscopic and microscopic analyses clearly reveal the formation of RuO2/TiO2 heterojunction and Schottky junction at the Ru/TiO2 interface. When the TiO2 nanobelts are excited, the co-existence of Ru and RuO2 nanoparticles on the nanobelt surface allows for highly efficient separately vectoring transport of photogenerated electrons and holes. Consequently, we have observed effective H2 evolution on the Ru surface with simultaneous O2 evolution on the RuO2 surfaces upon photoexcitation of the Ru-RuO2/TiO2 heteronanostructures in pure water. Further, by adjusting annealing period and temperature, we can tune the interface ratio of Ru/TiO2 and RuO2/TiO2, which is crucial to the overall efficiency for photocatalytic water splitting.

Resume : To limit the consumption of fossil fuels, hot water production by using photothermal solar receptors is growing in importance. An efficient photothermal receptor have to display a high solar absorptance (α>0.9), in the UV-VIS and near-IR regions (0.5-2µm) with a low thermal emittance (ε<0.1), in the mid-far infrared region (2-20µm) [1-3]. Here we report for the first time the formation of the solar selective CuO layer by the electrophoretic deposition (EPD) of CuO nanoparticles. A tandem absorber-reflector system is formed of CuO thin film and a highly IR reflecting metallic substrate, respectively. CuO suspensions are characterized by Dynamic light scattering (DLS) and Small angle X-Ray diffraction (SAXS) where they show to be stable during the time of the experiment. X-ray diffraction (XRD), scanning electron microscopy (SEM), UV-vis-NIR spectra and Fourier transform (FTIR) spectra are used to characterize the composition, microstructure and the final optical properties of the films obtained. These CuO tandem systems obtained by EPD exhibits the required optical properties in comparison to traditional processing techniques usually used. [1] Bogaerts WF, Lampert CM. Materials for Photothermal Energy Conversion. Journal of Materials Science. 1983;18:2847-75. [2] Charlot A, Bruguier O, Toquer G, Grandjean A, Deschanels X. Nanocomposites derived from silica and carbon for low temperature photothermal conversion. Thin Solid Films. 2014;553:157-60. [3] Charlot A, Deschanels X, Toquer G. Submicron coating of SiO2 nanoparticles from electrophoretic deposition. Thin Solid Films. 2014;553:148-52.

Resume : This work shows how the metastable high-temperature beta-Bi2O3 phase is prepared at low temperature and stabilized at room temperature in thin films, by using UV-light as an alternative energy source to the traditional thermal processing methods. Thin films of this oxide were prepared at only 250ºC, far below the temperature at which the phase is thermodynamically stable, from strong UV-absorbing solutions containing a bismuth(III)-N-methyldiethanolamine complex.[1-2] The beta-phase is not only stabilized at room temperature, but also shows a wide temperature range of chemical stability, between room temperature and 450ºC. The use of advanced characterization techniques, X-ray synchrotron radiation, four-circle diffractometry and Combined Analysis, allows us to unequivocally identify the development of the pure beta-Bi2O3 tetragonal polymorph in the films. Electrical measurements carried out close to room temperature in the beta-Bi2O3 films indicate a behavior compatible to that measured in bulk beta-Bi2O3 materials at the high temperatures where the phase is thermodynamically stable. The potential of these materials for visible light activated photocatalysis is demonstrated by the remarkable visible light absorption of these beta-Bi2O3 films, which is associated to an excellent photodegradation of dyes. 1. D.Perez-Mezcua, R.Sirera, R.Jimenez, I.Bretos, C.De Dobbelaere, A.Hardy, M.K. Van Bael and M.L.Calzada. J.Mater.Chem.C, 2014, 2, 8750. 2. I.Bretos, R.Jiménez, A.Wu, A.Kingon, P.M.Vilarinho and M.L.Calzada. Adv.Mater., 2014, 26, 1405. This work has been financed by the Spanish Project MAT2013-40489-P.

Resume : In the field of electronics and telecommunications, the number of functionalities (networking, imaging, data processing) is increasing at high speed while the available space for their implementation in systems is decreasing. If transistors and magnetic materials reached a high degree of integration, it is not the case for the passive components (capacitors, resonators, filters, piezoelectric transducers…), each of them usually carrying out a single function and occupying a considerable surface. The current trend aims developing new nanosized components and since 20 years, significant progress in processing nanostructured ceramics and composites was achieved. An intense research effort was focused on downscaling ferroelectric particle size with the objective to better understand grain size effect on dielectric properties. Dielectric characteristics can be tailored through the control of grain size, chemistry and defects. In addition and as shown more recently, strain and interfaces engineering represent additional degrees of freedom towards properties control. Producing well controlled ferroelectric nanoparticles and processing dense nanostructured ceramics are thus challenging and have led to an increased interest on low temperature wet chemistry synthesis and advanced sintering techniques. We illustrate here the potentialities and the flexibility of the seed growth process, the supercritical fluid synthesis and Spark Plasma Sintering to yield functional ceramics ((Ba,Sr)TiO3 and Ba,ZrTiO3 ) and components assembly ((Ba,Sr)TiO3/ MgO,SiO2) with controlled nanostructure and original properties. An overview of the strategies based on such fast processes will be presented focusing on the impact on properties.

Resume : The most common piezoelectric materials are lead zirconate titanate (Pb(Zr,Ti)O3 or PZT) due to their ferroelectric and piezoelectric properties. However, due to the effects of lead toxicity, it has recently desired to develop lead-free piezoelectric materials for environmental protection. Therefore, lead-free piezoelectric materials have been attracting attention worldwide as new materials in place of PZT-based systems. Bismuth sodium titanate ceramics (Bi0.5Na0.5TiO3 or BNT) with strong ferroelectric properties (remnant polarization Pr=38 µC/cm2, Curie temperature Tc= 320°C and coercive field Ec= 73 kV/cm) and relatively high piezoelectric properties (d33=60-90 pm/V) is considered a promising lead-free piezoelectric material. The sol-gel method is widely used for the fabrication of ferroelectric thin films due to short and simple fabrication equipment. This technique offers good stoichiometry control of the film composition and good adhesion between the substrate and the coat solution. In this work Bi0.5Na0.5TiO3 thin films were prepared by a Sol-Gel/Spin-Coating process. Bismuth nitrate III penta-hydrate, sodium nitrate and titanium (IV) isopropoxide were used as starting chemical reagents to prepare a BNT precursor sol. The solution is deposited by spin coating on a Pt/Ti/SiO2/Si substrate. Then thermal processes (drying, pyrolysis and annealing) were applied; BNT films were annealed with the rapid thermal processor (RTP) which is a little different from the conventional process. In the conventional process, films are annealed at high temperatures after multiple spin-coatings, while in the RTP annealing is applied after each layer deposition in order to reduce thermal stresses. First results of piezoelectric characterizations at the macroscopic level showed promising piezoelectric response (d33=42 pm/V at 270 kV/cm). BixNa1-xTiO3 films are currently prepared with some modifications of the chemical composition (0.4 < x < 0.6) to study the influence of the A-site composition on the structural, microstructural and electrical properties. Key words: Piezoelectric, lead-free, Sol-Gel, thin films, BNT.

Resume : Due to their high-performance dielectric, piezoelectric, and ferroelectric properties, 2D ferroelectric films have been used in various applications, such as nonvolatile random access memory, sensors, energy scavengers, structural health monitors, actuators, and micro-electromechanical systems. However, conventional 2D films have architectures with limited surface area, which reduces their potential performance in many applications, thus demonstrating the need to create 3D structured ferroelectric materials. Current synthesis techniques, such as metalorganic chemical vapor deposition and plasma-enhanced vapor deposition, have been used to create 3D ferroelectric materials, but harsh processing parameters limit their use for various applications. These harsh parameters can be mitigated by utilizing solution-based processing methods. This research develops a methodology to synthesize a conformal barium titanate (BaTiO3) textured film on patterned silicon wafers via a hydrothermal synthesis. Additional optimization of the hydrothermal reaction results in a high relative dielectric constant of 1600 and a d33 piezoelectric strain coefficient of 100 pm/V, which is a 100% increase over previously reported d33 values for similar BaTiO3 films. Therefore, this processing optimization provides a route towards synthesizing 3D nanostructured, high-performance BaTiO3 films using solution processing techniques thus offering increased surface area over conventional 2D ferroelectric films.

Resume : In this talk we will discuss phonon scattering mechanisms in ferroelectric materials and will demonstrate how mobile coherent interfaces (ferroelastic domain walls) can be used to actively regulate phonon transport. We will show how 90° ferroelastic domain walls in ferroelectric thin films of Pb(Zr,Ti)O3 and 71° domain walls in BiFeO3 can scatter heat carrying phonons at room temperature. Under the application of an electric field, the ferroelastic domain structure in Pb(Zr,Ti)O3 bilayers and single-phase membranes can be modified, resulting in increased scattering of phonons with sub-second response times. This field tuning of thermal conductivity effect will be shown for Pb(Zr,Ti)O3 bilayers and membranes where a ~ -12% and ~ +13% change in thermal conductivity at room temperature was achieved, respectively, with the application of ~460 kV/cm electric field. Utilizing PFM, in operando channeling contrast SEM, and synchrotron-based microdiffraction techniques, we identify and quantify the domain wall restructuring responsible for the changes in thermal conductivity. The response is rapid and recoverable and this demonstration of a voltage tunable thermal conductivity at room temperature without passing through phase transitions or physically separating components opens a pathway to develop phononic devices and may also be exploited for low input energy nanoscale temperature control. Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Resume : Multiferroic materials are among the most attractive multifunctional materials due to the possibility of combining and coupling ferroelectric, ferromagnetic and ferroelastic orders leading to many multifunctional applications: ferromagnetic memories, ferroelectric sensors, ferroelastic detectors, actuators and other microwave devices. Two-phases multiferroics, combining piezoelectric and magnetostrictive phases, present the advantage to enhance magnetoelectric (ME) coupling through interfaces and strain interaction. The coupling is observed by means of ferroelectric phase transition induced by magnetic field in perovskite structures ((Bax,Sr1-x)TiO3, Pb(Zrx,Ti1-xO)3) or vice versa ferrimagnetism induced by electric field in spinel structures (CoFe2O4). The strain in the most common multilayer structures is limited due to the substrate-imposed clamping effect and correspondingly the magnetoelectric effect is small. Therefore designing innovative architectures is thus a challenge in the field of multiferroic nanocomposites. In our research, two strategies are followed for the material design: i) (1,3) structure where vertically aligned ferrimagnetic nanopillar arrays (1) are embedded in a ferroelectric matrix (3) and ii) (1,3) structure where three-dimensional self-supported interconnected ferrimagnetic nanowire networks (1) are embedded into a ferroelectric matrix (3). The objective is to increase the strain and ME coupling of multiferroic nanocomposites by increasing interfacial surface area between the two phases, by reducing clamping between multiferroic material and a rigid substrate or by strengthening the coupling between two phases. The first approach combines electrochemical and sol gel processes. Its efficiency and flexibility has been demonstrated in the case of Ni@ BaTiO3 nanocables. The electrodeposition of CoFe2 vertical nanopillar arrays and crossed nanowire networks within the vertical or interconnected pores is followed by template dissolution, sol-gel impregnation of Pb(Zrx,Ti1-xO)3 and thermal treatment to oxidize the magnetic phase and to crystallize the dielectric phase at the same time while preserving the global architecture. The second approach we will develop is the deposition by magnetron sputtering of (Bax,Sr1-x)TiO3 onto supported CoFe2 and CoFe2O4 nanopillar arrays. The microstructural and morphological evaluations of nanocomposites include incidence XRD, HRSEM and HRTEM characterizations. For magnetic hysteresis measurements, an alternating gradient magnetometer was utilized. For dielectric measurements, the capacitance-frequency over wide range of temperatures and impedance spectroscopy were analyzed using an impedance analyzer. The ME coefficient is determined as a function of DC magnetic field and temperature using adjusted Quantum Design physical property measurement system (PPMS). The samples are mounted in longitudinal geometry, i.e. ME voltage is parallel to the direction of AC and DC magnetic field. Two types of two-phases multiferroic nanocomposites have been prepared. The magnetoelectric coupling in the nanopillar arrays embedded inside the matrix have been observed and can be interpreted by the good ferroelectricity and ferrimagnetism of the two phases, along with the reduced clamping effect and the big interface area which can enhance the strain interaction.

Resume : Low dimensional piezoelectric and ferroelectric materials have recently attracted ample attention for their potential application in nanogenerators for energy harvesting and sensors. Moreover, it has been reported that the strain induced by epitaxial films on lattice mismatched substrates or by the 1D growth in nanowires or nanorods may enhance the ferroelectric properties such as the Curie temperature, permittivity or polarizability, thereby increasing the output power and/or extending the operational temperature range of the fabricated nanogenerators. Among the proposed lead-free compositions, (Ba0.85Ca0.15)(Zr0.1Ti0.9)O3 ceramics, also known as BCT-0.5BZT, is one of the strongest alternatives due to its high piezoelectric coefficient, reported as high as 620 pC/N in bulk form. This composition exhibits a morphotropic phase boundary (MPB) between the ferroelectric tetragonal and rhomboedral phases close to room temperature. However, the low Curie temperature (TC) in the bulk of about 90ºC somewhat limits many potential applications, and thus an enhancement of the operational temperature range would be desirable. Here we take advantage of the strain produced by lattice distortions induced by a novel confined one-dimensional growth process used in the fabrication of BCT-0.5BZT nanowires with high aspect ratio and greatly enhanced TC. The BCT-0.5BZT nanowires were fabricated using a simple template-assisted sol-gel methodology, and exhibited a TC ~ 300ºC, three times higher than in the bulk. Our work presents a simple route to obtain confinement-induced strain in ferroelectric nanowires which can be used to enhance and tune their properties.

Resume : Photoelectrochemical (PEC) water splitting has drawn much attention because it provides a means of producing renewable hydrogen. TiO2 is the most common material for use in PEC water splitting by virtue of its attractive virtues, such as non-toxicity, high chemical stability, and suitable band structure. However, the large bandgap of TiO2 limits the absorption of visible light, which further hinders its practical use. To address this problem, deposition of another semiconductor with the narrow bandgap capable of visible light harvesting has been proposed and realized. In this study, TiO2 nanowires were decorated with In2S3 nanoparticles with a controllable amount by using a delicate chemical bath deposition method. The composite nanowires were used as the photoanode for PEC water splitting. The I-V, I-t and IPCE data showed that In2S3-decorated TiO2 exhibited significantly enhanced photocurrent of water oxidation under simulated AM1.5 illumination, which can be attributed to the visible light absorption of In2S3 as well as the improved charge separation at the interface. Time-resolved photoluminescence and electrochemical impedance spectroscopy were employed to depict the charge transfer events across the interface and realize the quantitative effect of In2S3. The results of charge dynamics were further correlated with the corresponding PEC performance. This correlation may provide insightful information when applying TiO2-base composite nanostructures in relevant photoconversion processes.

Resume : Ferrite spinels (MFe2O4) – in particular in nanocrystalline form – are of interest for a broad range of applications such as electronics, medicine and energy storage, to mention only a few. This is due in part to their unique size-dependent magnetic and electronic properties. Zinc ferrite (ZnFe2O4, ZFO) is a prototypical compound of this class of materials. Among others, it has been shown to exhibit tailorable properties and further is capable of delivering high specific capacities when used as an anode material in lithium-ion batteries. Here, we describe a facile synthesis method to produce high quality ZFO nanocrystals with narrow size distribution (around 4 nm diameter). The particles were prepared by a microwave-assisted wet chemical process, following the work of Niederberger et al. The phase purity, high crystallinity and “cluster” size were confirmed by various state-of-the-art characterization techniques, including electron microscopy, XPS, XRD, SQUID magnetometry, and Mössbauer spectroscopy. The as-prepared ZFO nanocrystals – with inversion parameter Lambda = 0.68 ± 0.02 – exhibit spin glass-like behavior at low temperatures and demonstrate high specific capacities (>700 mAh/g ZFO at C/10) in Li half-cells with reasonably high areal loading (>2.0 mg ZFO/cm2). The battery cells can be cycled in a stable manner at various C-rates over hundreds of cycles. Lastly, we also provide insights into the electrochemical conversion process from XANES.

Resume : The transparent conductive aluminum-doped zinc oxide (AZO) attracts attention as an alternative for indium tin oxide. Still, it is unclear how different point defects affect its properties. Here, we explore which defects contribute to the conductivity of AZO nanospheres and how they can be tuned by solvolysis synthesis and annealing. Using a combination of NMR, Infrared and Raman spectroscopy, the occurrence and position of the Al dopant was determined in these samples. Moreover, the microwave cavity perturbation technique (MCPT) was used to qualitatively compare the conductivity of the powders. From the results of MCPT we can conclude that, a combination of annealing and prolonged refluxing leads to an increased conductivity. Also a significant rise of an NMR Knight Shift and a broad and intense FTIR band attributed to surface plasmon resonance, both indicate free charge carriers. This is in agreement with Raman spectra showing the presence of clusters of Zn interstitials in all samples. Our first-principles calculations corroborate these findings, that annealing of Al interstitials leads to the formation of zinc interstitials in combination with substitutional Al, which results in an increased conductivity in AZO. The authors acknowledge the Research Foundation Flanders (FWO project No. G018914 HAR) for financial support.

Resume : With the growing concern about the environmental and energy issues, photocatalysis using semiconductor like TiO2 has drawn intensive attention in recent years. Under light illumination, electrons and holes are generated within TiO2, which further react with water and oxygen to produce highly reactive radicals for pollutant degradation. However, once light irradiation is ceased, electron/hole generation is ceased and TiO2 becomes inactive, which hinders its practical use. Here, we reported a tri-functional TiO2-Au@Cu7S4 composite photocatalyst, which displays remarkable photocatalytic performance under light illumination yet persists noticeable catalytic activity after light irradiation is turned off. The samples were prepared by decorating TiO2 nanowires with Au@Cu7S4 yolk@shell nanocrystals. Due to the relative band alignment, decoration of Au@Cu7S4 can enhance the charge separation of TiO2, therefore improving the overall photocatalytic activity. Besides, Au@Cu7S4 nanocrystals were capable of absorbing visible light, which is beneficial for improving photon harvesting of TiO2. Furthermore, by virtue of the peroxidase-like property of Au and Fenton reagent characteristics of Cu7S4, Au@Cu7S4 can catalyze H2O2 to generate hydroxyl radicals for proceeding pollutant degradation in darkness.

Resume : The results of the study of local formation (diameter 100 um) of thorium oxide coatings on SiO2/Si(001) surface by electrochemical deposition are presented. It was found that the electrochemical deposition of thorium atoms from an acetone solution of Th(NO3)4 with the small presence of water on silicon surface lead to the formation of thorium compounds. The results of surface analysis by local XPS and X-ray photoemission indicate that these compounds represent a thorium-, silicon-, oxygen- and carbon-based compounds. After 28 hours annealing at 1350 °C at atmosphere carbon pulled completely, and the compound transmit to the thorium silicate films ThSiO4. Our primary study of ThSiO4 compound by REELS show that this system have energy gap ~7.6 eV and can be useful for further research of «nuclear clocks» based on low-lying isomeric transition in 229Th isotope with energy 7.8 ± 0.5 eV.

Resume : A recently emerging class of solid-state hybrid organic–inorganic perovskite-based solar cells, using CH3NH3PbX3 (X=Cl, Br, I) as light harvesting materials, had demonstrated remarkably high power conversion efficiencies of nearly 20%. Most state-of-the-art perovskite solar cells typically have a device structure that is based on a high-temperature sintered metal oxide as electron selection layer which may cause the limitation of perovskite solar cells to be deposited on flexible substrates and affect their compatibility with fabrication processes in multi-junction solar cells. In this work, the utilization of atomically thin titania (Ti0.87O2) deposited at room temperature as an ultra-thin electron selection layer in perovskite solar cell was demonstrated. Through Langmuir-Blodgett deposition process at room temperature, Ti0.87O2 with 2-dimensional morphology was conformally deposited on FTO substrate with a high coverage and eliminated the requirement of high temperature process (over 500C) to deposit conventional metal oxide layer. The incorporation of multi-layer Ti0.87O2 (around 5 nm) effectively decreased the recombination of electron and hole and leaded to a reduced leakage current. This resulted in a promising device performance (13.77%) that is compatible to the device fabricated using high-temperature sintered metal oxide as electron selection layer. Our results indicate that 2-dimensiolal titania with atomic scale could be a simple solution-processable alternative to conventional metal oxide as electron selection layer in high performance perovskite solar cells or as interlayer in other optoelectronic devices.

Resume : The results of ab initio calculations for SrTiO3, BaTiO3, PbTiO3 and CaTiO3 (001), (011) and (111) surfaces using a hybrid description of exchange and correlation are presented [1-4]. In the case of the neutral AO-terminated (001) surface for SrTiO3, BaTiO3, PbTiO3 and CaTiO3 perovskites, all upper layer A atoms relax inwards, while all second layer atoms relax outwards. For practically all ABO3 perovskites, the surface rumpling is considerably larger for the AO-terminated than for the BO2-terminated (001) surface, but their surface energies always are almost equal. Just opposite, different terminations of the polar (011) ABO3 surface lead to very different surface energies for the O-terminated, A-terminated, and BO-terminated (011) surface, respectively. The surface energies for all calculated polar (111) surfaces are considerably larger than even for (011) surfaces. A considerable increase in the Ti-O chemical bond covalency near the (011) surface as compared to the bulk and to the (111) and (001) surfaces in considered ABO3 perovskites were predicted. References: 1. R.I. Eglitis, Appl. Surf. Sci. 358, 556 (2015). 2. R.I. Eglitis, Solid State Ionics 230, 43 (2013). 3. R.I. Eglitis and D. Vanderbilt, Phys. Rev. B 76, 155439 (2007). 4. R.I. Eglitis and D. Vanderbilt, Phys. Rev. B 77, 195408 (2008).

Resume : In this work, CuxCo2-xO4 (CCO) thin films, x =0 to x= 0.5, were successfully deposited on soda-lime glass substrates using sol-gel technique. The effect of growth parameters such as doping concentration, annealing and thickness on physical properties of the films were analyzed in detail. Following a wide range of characterization tools to investigate structural, electrical and optical properties of the deposited films it was deduced that the CCO material can be utilized as a potential absorber layer for the construction of high performance inorganic solar cells. From the conducted transmission and transmission measurements it was found out that despite their low thickness (74 nm) all of the films exhibited high optical absorption in the 325-1100 nm wavelength range. Following the doping of cobalt-oxide with different copper (Cu) concentrations not only a significant decrease in transmittance but also a dramatic increase in the room temperature conductivity of Co3O4 (more than two orders of magnitude) were observed. In addition to these, the reflectance spectra recorded for cobalt-oxide doped with different Cu concentrations revealed that the reflection of the films slightly increased with increase of Cu concentration. As Co3O4 compound has two direct band gap, the effect of Cu-doping on these band gaps was studied extensively through the recorded transmittance and reflection spectra. Results showed that in contrast to its high energy band gap, which was widened following the incorporation of Cu atoms (from 2.28 to 2.37eV for x=0 and 0.1, respectively) and remained constant by further increase in Cu concentration, its low band gap energy exhibited a systematic decrease from 1.48 to 1.34eV by increasing x from 0 to 0.5.

Resume : Thermohydrolysis is a very convenient way to synthesize metallic oxide nanostructures in aqueous solutions, especially when assisted by microwave irradiation and/or templates. Strangely enough, if one may find huge amounts of recipes, thermodynamical modelisation of such systems is scarce. Worse, even for well-known systems, thermodynamical data as hydrolysis or complexation constants may be missing or not reliable, preventing any calculation. We explain in this study a method to get the values of thermodynamical constants at temperatures ranging from room temperature to thermohydrolysis temperature, allowing the determination of the speciation and supersaturation of Ti(IV) and Sn(IV) systems in chlorhydric or sulfuric aqueous solutions. By combining a critical review of literature data, models for temperature dependence and solubility measurements in different physico-chemical conditions, we were able to select the right set of values among contradictory studies and to choose the right extrapolation with temperature. We applied these new data to compute supersaturation in different thermohydrolysis conditions of mixed Ti(IV)-Sn(IV) systems, and found it consistent with experimental results as yield and solid composition. Hence this approach is a useful predictive tool for the synthesis of mixed oxides.

Resume : Nano-structured copper oxide surface coatings offer promising properties, which make them interesting for a large number of technical applications. Examples are the use of copper oxide nanoflakes for supercapacitors [1] or for solar cells [2]. Furthermore copper oxides are low-cost materials with highly disinfecting qualities and can thus also be used as a suitable material for self-sterilizing surfaces or biosensors [3]. The study presents the plasma assisted deposition of high quality copper oxide nanoparticles at atmospheric pressure. The depositions were achieved with a direct current, non-thermal atmospheric pressure plasma source [4]. Different materials such as borosilicate glass, paper and polycarbonate were coated successfully. The focus of this work is the physical understanding of the obtained films by thorough investigation using scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy. SEM analysis revealed the formation of densely packed, vertically aligned copper oxide nanoflakes with high aspect ratio, whereat the treatment time has considerable influence on the morphology and chemical composition of the copper oxide layers. [1] Z. Endut, M. Hamdi and W. J. Basirun, Thin Solid Films, 528, 213-216 (2013) [2] H. Y. Shiu, C. M. Tsai, S. Y. Chen, and T. R. Yew, J. Mater. Chem., 21 17646-17650 (2011) [3] O. Akhavan and E. Ghaderi, J. Mater. Chem., 21, 12935 (2011) [4] A.A.H. Mohamed, J.F. Kolb, K.H. Schoenbach, Eur. Phys. J. D 60/3 517 (2010)

Resume : ZnO is one of the most important transition metal oxides. It finds application in optoelectronics, cosmetics, sensors, just to cite a few [1]. ZnO electrochemical synthesis is particularly interesting as a green, cheap and easy procedure [2]. Here we report on the green electrochemical synthesis of ZnO nanoparticles (NPs) in aqueous medium. The electrolyte was composed of a stabilizing cationic surfactant (cetyltrimethylammonium bromide, CTAB) dissolved in NaHCO3 30 mM aqueous solution at pH ~ 8. The electrosynthesis was carried out galvanostatically at 10 mA/cm2, either at room temperature or at 80°C for 1h. Gel-like pristine colloids, made of mixed Zn carbonates and hydroxides, underwent post-synthesis thermal treatments to allow complete conversion to ZnO with good stoichiometry. Calcination was carried out at 300°C or 600°C for 1h. All nanomaterials were characterized at each step of their production by transmission electron microscopy (TEM), UV-Vis, infrared (FT-IR) and X-ray photoelectron (XPS) spectroscopies. In particular, morphological analysis revealed that more ordered elongated ZnO structures could be obtained preparing colloids at 80°C and calcining at 300°C. 1 Ü. Özgür et al., J. Appl. Phys., 98 (2005), 041301. 2 R. A. Picca et al., Electrochim. Acta, 178 (2015), 45.

Resume : Low-cost semiconducting materials and facile preparation of photovoltaic junctions constitute long-standing goals of photoactive materials research. The intense research on nanotubes conducting polymer heterojunctions and their application for photocurrent generation, water splitting and energy storage is observed. Here, we show preparation of ordered inorganic-organic heterojunction where hydrogenated titania nanotubes (H-TiO2 NT) were infiltrated by poly(3,4-ethylenedioxythiophene) modified with redox centres formed by Prussian blue matrix. The polymer deposition was realized via two subsequent processes covering a) potentiostatic polymerisation carried out at H-TiO2 electrode immersed in solution of EDOT monomer and ferricyanide ions and b) cycling voltammetry routs in solution containing Fe2 ions. Raman spectra and SEM together with EDX inspection prove polymer infiltration down to the bottom of nanotubes and incorporation of iron atoms. The composite material exhibits superior properties and its photoactivity is much higher in comparison to pristine H-TiO2. At 0.8 V vs. Ag/AgCl/0.1M KCl, the photocurrent density for H-TiO2 reaches 60 μA/cm2 whereas obtained junction generates almost 300 μA/cm2. Cyclic voltammetry curves registered for inorganic-organic composite exhibit clear reversible reduction/oxidation peaks attributed to the Fe 2 /Fe3 redox activity. Financial support from the National Science Center (2012/07/D/ST5/02269) is gratefully acknowledged.

Resume : Solution based thermochromic VO2 particles has been developed with hydrothermal synthesis, which is a rapid way to obtain VO2 in different phases under economical and environmentally friendly conditions. VO2 was successfully synthesized by rapid single step hydrothermal process using V2O5 and oxalic acid as precursors. The obtained VO2 is characterized by X-Ray powder diffraction, and DSC. We also demonstrate that the VO2 in the form of a colloidal dispersion can be easily incorporated into thin plastic thermochromic films that may be used as smart windows for energy saving.

Resume : ZnS is a semiconductor extensively studied because of its appealing electronic properties. Though the thermal conversion of ZnS to ZnO has been widely industrially and synthetically exploited [1, 2], the thermal stability of ZnS upon thermal treatment can become a critical issue in many applications. In this regard, the literature presents only few reports on bulk ZnS, though, as far as nanostructures are concerned, no comprehensive study has been reported yet. Additionally, the knowledge of the exact composition, surface chemistry and structure of these nanostructures is particularly important to design a rational functionalization strategy, or when the system’s ability to interact with other species is explored. In this report, a systematic study of the thermal behaviour of nanosized ZnS has been carried out following the structural and chemical evolution to ZnO upon thermal treatment in air at different temperatures. Two different simple wet chemistry synthetic routes, namely hydrothermal synthesis and miniemulsion, were employed to obtain the starting material. A comparison of the effects of thermal treatments at different temperatures on their structural evolution has been carried out by XRD, XPS, Raman, FT-IR, ESR and XAS. [1] L. Khomenkova, P. Fernández, and J. Piqueras, Cryst. Growth Des., vol. 7, no. 4, pp. 836–839, Apr. 2007. [2] X. Wu, K. Li, and H. Wang, J. Hazard. Mater., vol. 174, no. 1–3, pp. 573–80, Feb. 2010.

Resume : During recent years, tungstate Strontium scheelite structure has been extensively studied because of their properties and potential applications in various fields, particularly the catalysis and the photocatalysis1. These properties and associated applications depend on the morphology of the individual particles. The aim of this work is to see the influence of the microcrystals morphologies on photocatalytic degradation of Rhodamine-B and blue mythelene in aqueous medium. For that, we synthesized micro-nanostructured strontium tungstate with two morphologies spindles and spheres. The SrWO4 powders have been synthesized at room temperature using an aqueous mineralization processes. All obtained samples were characterized by X-ray diffraction, scanning electron microscopy and diffuse reflectance spectra to identify the structure, the morphology and the optical properties. XRD and SEM results demonstrate that the as obtained SrWO4 particles are high purity, well crystallized and exhibit a relatively uniform morphology. The photocatalytic activities were conducted for the two morphologies under UV excitation and reported as a function of time and concentration. The photodegradation reactivity was discussed as a function of the morphology and the crystallization degrees. The influence of calcination temperature on photocatalytic activities of the tetragonal SrWO4 for two morphologies was investigated within the limits of the stability of the morphology. (1) Chen, D.; Liu, Z.; Ouyang, S.; Ye, J. Phy Chem..2011, 115, 15778- 15784 Acknowledgements We gratefully acknowledge the Regional Council of Provence-Alpes-Côte d’Azur, General Council of Var, and the agglomeration community of Toulon Provence Mediterranean for their financial supports in the framework of "M2D2" project.

Resume : Herein we are presenting comparative study on as-deposited and one month storaged in plastic boxes ZnO nanorods obtained by electrodeposition (ED) at 80 °C and chemical spray pyrolysis (CSP) at 550 °C. Morphological, crystalline, wetting properties and surface composition were investigated using SEM, XRD, XPS, and water contact angle (CA) measurements. It was found that the surface of as-deposited ED-rods is more hydroxylated compared to the surface of the CSP rods. According to XPS, the relative amount of (OH) groups on the surface of ED rods is two times higher than on the surface of CSP rods. This result is in a good correspondence with wettability measurements: CA of ED rods is ca. 5° and CA of CSP rods is ca. 12°. Also the surface contamination ability differs for ED and CSP rods. After one month of storage in plastic boxes, a change in the wettability behavior from hydrophilic (CA=5°) to highly hydrophobic (CA=125°) was observed for ED rods. CSP rods did not change their hydrophilic nature (CA 40°), indicating that the surface of CSP rods stays cleaner longer. According to XPS relative amount of carbon species on one month stored ED rod sample is 3 times higher than on similar CSP rod sample. The relationship between the surface composition of as-deposited and aged ZnO rods, assessment of their surface contamination and wetting properties will be discussed.

Resume : Transparent conductive oxides (TCOs) are an important and unique class of materials in the photovoltaics industry; they have several key features such as high optical transparency in the visible region and good electrical conductivity. While indium-doped tin oxide (ITO) is the most widely used material, due to the rarity and expensive cost of indium alternative materials need to be found. Research has been carried out using low cost, abundant, non-toxic elements to dope zinc oxide and tin oxide as feasible alternative materials to ITO. Aerosol Assisted Chemical Vapour Deposition (AACVD) would provide a simple method of depositing metal oxide on to a substrate and is potentially scalable as an industrial process. Marks et al have synthesised ITO, ZTO and IZO from metal nitrates by spin coating. This method has been adapted to deposit ZnO, doped ZnO, SnO2 from an nitrate based aqueous system. The conductivity and transparency properties of doped metal oxides will be analysed to determine their utility as a TCO material. Also reported herein is a synthetic approach to suitable CVD precursors for the deposition of metal oxides and doped metal oxides. Amide ligands will be reacted with metal precursors; the decomposition of the resulting complexes will be determined by thermal gravimetric analysis.

Resume : LaNiO3 (LNO) has attracted much attention over the past few years, as a conducting layer for applications in ferroelectric memories. Nevertheless, due to its crystalline and electrical properties LNO is a very promising for the use as buffer layer for high temperature superconductor (HTC) coated conductors. LNO has a perovskite structure with the lattice parameter of 3,84Å having a good lattice match with the Ni-based biaxially textured substrate and the common used buffer layers such as ceria or YSZ, and, as consequence, it can be easily integrated in the conventional buffer layer architecture. Moreover, the metallic behavior of LNO makes possible its use as a conducting buffer layer. This paper presents the results on the preparation of the precursor solution for the deposition of epitaxial LaNiO3 thin films by the chemical solution deposition (CSD) method starting from lanthanum and nickel acetylacetonates. For a better understanding of the precursor chemistry, the precursor powder as well as the individual precursors have been investigated by TG-DTA thermal analyses coupled with mass spectrometry (MS). Perovskite nickel oxides LaNiO3 thin films were deposited from metalorganic solution, by spin-coating on SrTiO3(100) single crystal substrates. Highly oriented LaNiO3 films with good out-of-plane and in plane textures have a FWHM of 0.3o and ω-scan of 0.4o, respectively. AFM analyses have shown smooth and crack-free surfaces. The resistance vs. temperature curves of the textured LaNiO3 films at 700 oC showed that the film has a good metallic behavior.

Resume : We report the effect of various annealing environment on the electrical properties of undoped and Al-doped ZnO (AZO) films prepared on cleaned soda lime glass substrates by sol gel spin coating process. To this end, these films were subjected to various annealing conditions varying temperature, pressure and duration. Then a detailed microstructural, bulk optoelectronic and surface electrical characterizations of these films were conducted using a range of experimental techniques, like XRD, AFM, FESEM, UV-Vis-NIR spectrophotometer, Hall probe measurement system, PL, XPS and STM/STS. All these films are found to have grown in ZnO hexagonal wurtzite structure with strong (002) orientation of the crystallites and with an average transmittance of above 85% in the visible range. However, electrical resistivities show a stronger dependency on the annealing conditions with the lowest value obtained being 4.62x10-2 Ωcm, which is due to an increased carrier concentration of 0.207×1020 cm-3 because of the presence of shallow level defects within the band gap (accounting to Zn interstitial and extended Zn interstitial) and carrier mobility of 6.51 cm2 V-1s-1 due to improved film microstructure. Room temperature STS measurements reveal semiconducting and rectifying behaviour in the AZO and ZnO films respectively. Local I-V from AZO film surfaces show larger tunnelling current than ZnO because of the presence of the increased carrier concentration due to Al doping. Additionally, the observed variation in the tunnelling characteristics over the film surface is found to be associated with the compositional variation. Understanding developed in this study will help in designing low cost scalable TCOs for wider technological applications.

Resume : ZnO nanorods synthesis has been attractive for researchers, because this kind of morphology has many applications in optical and electrical devices. This morphology helps to improve the catalytic and photoluminescent properties because ZnO is an n-type semiconductor with wide band gap (3.4 eV) and high exciton binding energy of 60 meV and it has a high transparency in the visible region so it can be used as transparent device. In this work, ZnO thin films were deposited by sputtering and SILAR (Successive Ionic Layer Adsorption and Reaction) method; these films shall be used as a substrates to grow aligned ZnO nanorods by chemical bath deposition (CBD). The physical and chemical methods are used to compare which one is better to obtain the best homogenous surface to grow ZnO aligned nanorods. ZnO nanorods define the optical and electrical properties of the thin film, so it is important that ZnO nanorods grow correctly aligned, and alignment depends on the characteristics of the substrate. Over this structure we grew CdS nanoparticles by chemical bath deposition. The growth of CdS nanoparticles on the ZnO nanorods improve the electrical response to a wavelength change; what makes that this heterojunction to be suitable as photosensor material. The properties of the heterojunction were characterized using XRD, SEM, XPS and electrical probes. The results will be discussed.

Resume : Transparent electrodes are essential to fabricate many electronic devices including LCD, OLED and organic photovoltaics (OPVs). While ITO is conventional transparent electrode for such devices, silver nanowire (AgNWs) have been considered as a strong alternative due to high electrical, optical properties. Such AgNW-based transparent electrode is studied to improve electrical properties by introducing various materials. Here, we examined what is the most dominant effect to improve the electrical properties of AgNW-based electrode with sol-gel ZnO layer by constructing three different architectures; We constructed transparent electrodes consisting of AgNW without ZnO layer, ZnO layer on AgNWs, AgNWs on ZnO layer. Then, the electrical properties were measured. The line resistance of the transparent electrode with sol-gel ZnO layer on AgNW layer was lower than that of the reference AgNW electrode. The transparent electrode with sol-gel ZnO layer under AgNW layer showed the lowest line resistance. Thus, we concluded that sol-gel ZnO is helpful to decrease electrical resistance of AgNW-based transparent electrode, but its degree depended on the position of the ZnO layer. We introduced AgNW transparent electrodes with three different architectures to OPVs. The OPVs adopting transparent electrode of AgNW on ZnO showed better efficiency than that with transparent electrode of AgNW under ZnO because of their high electrical conductivity.

Resume : Field emission (FE) is an alternative mechanism to extract electrons to be used in exhale biosensors. A Special gas concentration over a certain amount in the exhale of an individual can be a sign of a disease. Therefore, sensing gases in the breath of a human can be an alternative way of disease diagnosis. Zinc oxide (ZnO), with a wide and direct band gap of 3.37 eV, has been shown to be a prime candidate for the nano-scale, one dimensional, low power applications with higher device packaging density and more chemical sensitivity. FE from ZnO nanorods has attracted so much attention in recent years due to their potential application in vacuum nanoelectronic devices. In order to achieve an excellent FE performance from a nanorod array, the array’s resistance impact and the metal contact quality are important. Therefore, Aluminum doping can positively affect the FE properties as one of the most common dopants for ZnO. The Sensor has been fabricated using standard CMOS processing on the glass substrate. The seed layer was sputtered using a 2% Al-doped ZnO and the array of nanorods were then grown by chemical bath deposition. The morphology of the grown arrays was controlled using top and cross-sectional FESEM images. The crystalline quality of all doped samples was investigated using photoluminescence and x-ray diffraction. Finally, the IV curves and field emission responses were measured by Keithley-K361 parameter analyzer to estimate the impact of doping on the device electrical response.

Resume : The dissolution of polyolefins has been a growing problem; therefore, melt processing has been tacitly accepted as an obligation. In this work, polypropylene (PP) was modified on molecular level incorporating poly(ethylene glycol) (PEG) as graft segment (PP-g-PEG) in a range of 6 to 9 mol%. Gold nanoparticles were nucleated in the presence of the copolymer chains via redox reaction. The dissolution of the amphiphilic comb-type graft copolymers containing gold nanoparticles (80 nm in diameter) was achieved in toluene and successfully electrospun from its solution. The diameter of composite fibers was in the range of 0.3 to 2.5 µm. The design of the structurally organized copolymer fiber mats provided a support medium for the nanoparticles enhancing the active surface area for the catalytic applications. The resulting composite fibers exhibited rapid catalytic reduction of methylene blue (MB) dye in the presence of sodium borohydride (NaBH4) compared to corresponding composite cast film.

Resume : Metal oxides thin films have enormous applications in various fields such as transparent coatings, solar cells, optical devices, hard coatings and gas sensors. Various physical and chemical methods of film deposition are being employed to produce metal oxide films. These techniques have their own advantages and disadvantages. Many of these techniques require high vacuum, sophisticated instruments and hence, are economically expensive. Ultrasonic Nebulized Spray Pyrolysis of Aqueous Combustion Mixture (UNSPACM) is a method developed in our research group; combining the traditional nebulized spray pyrolysis technique with combustion synthesis and has led to the evolution of a novel method for thin film deposition. Spray pyrolysis has been proved to be a simple, versatile, inexpensive and effective technique to deposit metal oxide thin films and can be scaled up for large area depositions. The incorporation of ultrasonic nebulizer allows a greater degree of control in deposition parameters like concentration, gas flow etc. Here, aqueous combustion mixture has been used instead of only metal salt solution. The combustion process is highly exothermic, fast and produces nano sized, porous and pure products. Thus the kinetics of film formation on hot substrate is accelerated due to fast combustion reaction. This is an energetically economic, simple, fast process with a better control over homogeneity and stoichiometry of the film, through various tuning parameters. Thin films of oxide have been deposited using UNSPACM. The combustion mixture was prepared by mixing stoichiometric amounts of metal nitrate and fuel in aqueous medium of suitable concentration. The highly exothermic nature of the combustion reaction is exploited, in contrast to the endothermic decomposition of only aqueous metal nitrate solutions. Thus UNSPACM is a simple, easy and low cost method to obtain good metal oxide films, which can be easily employed for large scale depositions. In this talk, I shall introduce a novel method based on a combination of solution combustion and spray pyrolysis, which might become another major synthetic route for the deposition of highly crystalline and porous metal oxide films for various applications including gas sensing.

Resume : In the last years the importance of low cost, small size and transparent electronics has increased, therefore the search on low cost nanostructured materials and fabrication processes is essential. When sustainability comes into play, zinc-based, indium-free oxide semiconductor materials are preponderant. Within this context, zinc-tin oxide (Zn2SnO4) is one of the most promising oxide materials, being an n-type semiconductor with mobilities up to 10-15 cm2V-1s-1 and a wide band-gap of 3.6 eV being reported in nanostructures. Its multicomponent nature brings great application flexibility, as its properties can be easily tuned by adjusting the cationic ratio. Moreover, fabricating Zn2SnO4 nanostructures by solution-based methods is imperative to decrease complexity, cost and high temperature typical of vapor-phase processes. In this work we present a study of the solution-based synthesis of multicomponent semiconductor Zn2SnO4 nanowires with cubic phase, synthetized by an hydrothermal method at 200ºC during 24 hours in a furnace. Influence of synthesis time, solution pH and EDA’s concentration in the growth and type of nanostructures is explored. The nanostructures are characterized by XRD, SEM/EDS, EBSD, AFM and its electric properties accessed using in-situ characterization inside SEM chamber. Implementation of ZnO-based nanowires on electrolyte-gated field-effect transistors is demonstrated, resulting in On/Off ratio above 10^3.

Resume : Monolithic integration of functional oxides on silicon platforms is a key issue for future microelectronic devices. However, the controlled epitaxial growth of complex oxides on Si substrates is a challenging task regarding the strong structural, chemical and thermal dissimilitude existing between these materials [1]. This work describes new strategies to integrate advanced oxide nanowire thin films on Si substrates via a chemical solution deposition approach. Manganese based octahedral molecular sieve (OMS) nanowires were epitaxially grown on top of Si either through a direct precursor solution spin coating process, or through a templating synthesis using track-etched polymer templates. In either case, the nanowire growth mechanism involves the controlled growth of quartz thin films at the Si surface, which allowed the epitaxial stabilization and crystallization of OMS nanowires. ?-quartz layers were obtained by thermally activated devitrification of the native amorphous silica surface layer, driven by the confined precursor?s solutions containing alkaline earth cations [2]. These innovative growth methods have the possibility to modify the chemical composition and crystallographic structure of the OMS nanowires [3]. For example, the synthesis of different single crystalline epitaxial OMS nanowire films including Ba1+xMn8O16 hollandite, Sr1+xMn8O16, the quaternary oxides (BaSr)1+xMn8O16 and Ba1+xCoyMn8-yO16, and a new crystallographic phase, namely LaSr-2×4 OMS with enhanced ferromagnetic properties, on top of (100)-Si substrates is achieved. 1. J.Vila-Fungueiriño et al, Frontiers in Physics 3, 38, 2015 2. A.Carretero-Genevrier et al, Science 340, 827, 2013 3. A.Carretero-Genevrier et al, Chem Mater 26, 1019, 2014 Financial support from MINECO (MAT2014-51778-C2-1-R) is acknowledged. Can Fu acknowledges CSC (China) for a PhD fellowship.

Resume : We present a Raman spectroscopy study of the vibrational properties of epitaxial La1-xCaxMnO3 (LCMO) thin films epitaxially grown on LaAlO3 single crystalline substrates. The LCMO thin films have been prepared using the metal organic deposition (MOD) process. The film thickness varies from 20 to 100 nm. The evolution of the Raman modes versus the film thickness, the annealing temperature and stoichiometry have been investigated. The most pronounced Raman mode observed in our films is found to be centered around 661 cm-1. This mode is not often observed in such type of material and its origin is not yet determined in the literature. Most probably this mode is associated to the Jahn-Teller distortions of the perovskite-like structure of the LCMO thin films. In order to clarify the origin of this mode we investigated its evolution with the film thickness, the preparation conditions and composition. We observed a strong dependence on the Mn+3/Mn4+ ratio of the Raman spectra of the manganite thin films. The temperature effect has been investigated and some interesting behaviors have been obtained. In particular, we noted the apparition of three Raman modes between 410 and 450 cm-1 when the sample is cooled below the Curie temperature (TC).

Resume : In order to enhance water splitting efficiency, new types of photocatalyst are demanded. An efficient photocatalyst is expected to have the following features: a narrow band gap to absorb a broad part of the solar spectrum; small dimensions and high crystallinity to reduce the loss of charge carriers by recombination and a band gap slightly larger than 1.23 eV with band edges pinned correctly for overall water splitting. In this preliminary work, we show how to control the size of CuO and ZnO nanowires by oxidizing respectively an iron-copper alloy and a zinc-copper alloy by using a micro-afterglow produced downstream an argon-oxygen microwave plasma at atmospheric pressure. The micro-afterglow is a very oxidizing medium for it contains concentrations of oxygen atoms of a few 10^14 cm^-3 and a high concentration of excited oxygen molecules like O2(a1Δg). The presence of these species at moderate temperature can discriminate the growth rates of a given metal oxide along different directions, which promotes the emergence of nanostructures. So, by adjusting the parameters of treatment, we succeed in decreasing the diameter of these nanowires down to 4 nm in case of ZnO and to 5 nm in case of CuO. For CuO nanowires, which already possess a narrow band gap (2.2eV), quantum confinement should be observed and shift the conduction band to a suitable position for hydrogen production. For ZnO nanowires, which possess a large band gap (3.2eV), nitriding should help us decrease its band gap.

Resume : ZnO has attracted intensive research due to, for example, its application on the front side of solar cells, either as a transparent conductive layer, or as an active UV-sensitive front diode. Additionally, enhanced optical absorption can be achieved by ZnO nanostructures, like nanowires (NW). In this work we have deposited a thin ZnO seed layer of typically 20 nm thickness by pulsed laser deposition (PLD), followed by production of 50 nm wide and 1 to 5 micrometer long ZnO NW by a wet chemical process. First we compared the effect of persistent photoconductivity (PPC) upon UV irradiation, for nanowires samples and homogeneous ZnO films. Long characteristic decay times of 2 to 10 minutes were encountered. Next we performed spectrally resolved photocapacitance and photocurrent measurements (PC), at various temperatures, in order to characterize the influence of deep trap states. In current-voltage (I-V) characteristics in the dark, we found strong variation of the power law exponent as a function of temperature and applied electric field. Comparison of data with a transport model that includes the Trap-Filled Limit (TFL) regime, gives us an estimate of the energetic location and of the density of deep traps. We discuss the origin of such states with respect to bulk defects and adsorption of O2 molecules on the nanowire surfaces.

Resume : The conventional approaches to obtain inorganic material structures are a multi-step process including patterning with a polymer resist by lithographic methods, deposition of the target material, and lift-off process. Direct patterning of inorganic materials is an important issue in order to reduce multistep processes. Among inorganic materials, we focused on metal oxides precursor resists (i.e. zinc acetate, titanium butoxide, nickel naphthenate, etc.) due to their excellent optoelectronic and mechanical properties. Nanostructures with metal oxide precursor resist is transitioned to metal oxide nanostructures via heat treatment process. Electro-hydrodynamic lithography (EHL) and liquid transfer imprint lithography (LTIL) are good candidates to obtain fine metal oxides pattern. EHL, a promising non-contact soft-lithographic method, uses the capillary film instability to construct patterns, meaning that it is possible to use any material films has been destabilized by electrostatic force and that is not necessary for the material to have sensitivity to a special source such as an e-beam or light wavelength. Therefore, this is a good lithographic technique for direct patterning of any metal oxides precursor resists. In LTIL case, a resist in a mold is transferred to target substrate and cured by UV. LTIL can remove excess resist by splitting the mold from the coated resist film, so residue between the patterns is reduced to minimum. With LTIL, it is possible to broaden the application fields because pattern can easily form on transparent and flexible substrate over a large area. Our methods are simple, versatile and inexpensive, and have the potential to become a powerful tool for realizing metal oxides nanostructures. Herein, we prepared metal oxides precursor resists (i.e. TiO2, VO2, Fe3O4, ZnO, and NiO precursor resists) and patterned various nanostructures on flat and flexible substrates over a large area EHL and LTIL techniques. As a result, line, hole, and pillar array patterns and multilayer metal oxides nanostructures were successfully fabricated with various sizes. Fabricated nanostructures were developed to have functionalities via thermal annealing process which can be utilized in versatile applications.

Resume : Nanostructured semiconducting oxides play an important role in dye-sensitized devices for solar energy conversion, such as Dye-sensitized Solar Cells (DSSCs) or Dye-sensitized Photoelectrosynthesis Cells (DSPECs). In those devices the process of solar energy conversion relies on the injection of an electron from a photoinduced excited state of a photosensitizer to the conduction band of the semiconducting oxide, on which the sensitizer is chemically bound. One of the major requisite for good energy conversion performances is that of guarantee a stable binding of the dye molecules on the oxide surface throughout the entire nanostructured layer. This contribution illustrates an experimental stepwise strategy for the preparation of dye-sensitized nanostructured oxide electrodes, which includes a preliminary surface priming based on the chemistry of zirconium phosphates and phosphonates (ZP treatment(1)). This priming is aimed to creation of a robust and stable platform for the subsequent anchoring of phosphonate-derivatised photoactive systems. Time-of-flight secondary ion mass spectrometry and UV-visible spectroscopy were used for the physico-chemical characterisation of the surface, and the experimental results show that this strategy is well suited for efficient anchoring of phosphonic moieties on oxides of different nature (e.g. titanium dioxide, tin dioxide, etc..). (1) Spampinato, V. et al., Langmuir 26, 8400-8406, doi:10.1021/la9048314 (2010).

Resume : La0.7Ca0.3MnO3 perovskite type manganese material shows a ferromagnetic-paramagnetic phase transition with a metal-insulator transition and colossal magnetoresistance behaviour near of room temperature. This material has been studied to be used like tunnel junction in magneto-electronic devices. In mixed-valence manganites, magnetoresistance properties are managed by the amount of oxygen content in the sample. The oxygen defects produce important changes in crystal structure of manganites samples. X-Ray Diffraction, X-Ray Absorption Spectroscopy and Hard X-Ray Photoelectron Spectroscopy experiments have been carried out to study oxygen vacancies effects in de-oxygenated 20 nm La0.7Ca0.3MnO3-x thin film grown on SrTiO3 substrate by Pulsed Laser Deposition. Strong modification of the atomic structure has been obtained simultaneous to a decrease of the metal-to-insulator transition temperature and to a decrease of the Mn valence. XAS results show a high correlation between the structural, electronic and transport properties. For oxygen vacancies content above 10% a complete new diffraction pattern is obtained indicating the periodic arrange of the oxygen vacancies. Under these conditions the sample becomes highly insulating. The combination of high insulating with high crystallinity properties in de-oxygenated manganite material offers tremendous possibilities for magneto-electronic devices.

Resume : The great scientific attention was drawn by titanium dioxide decorated with metallic nanoparticles (NPs) such as silver due to enhanced photocatalytic properties, antibacterial properties, plasmonic properties, electron accumulation etc. One of the investigated method of metal nanoparticles deposition is photochemical method. Generally, photochemical method allows to obtain nanoparticles ranging from few to tens of nanometers in size. The main objective of this work is to investigate their deposition process and their influence of the nanoparticles morphology and microstructure. The parameters taken into consideration are metal precursor type (silver nitrate, imide, etc.), concentration of its solutions as well and the pH and the temperature during deposition process. Additional flexibility rises from the applied light conditions in photochemical reaction. In this case the visible light was used. We investigated also the influence of surfactants on the controlled growth of nanoparticles. Obtained microstructures were observed using high resolution SEM and AFM. The core-shell structures were obtained by partial exchange of silver with gold. Plasmonic properties core-shell particles were approximated by FDTD simulations. Nanoparticles were deposited on titanium dioxide substrate either as sol-gel thin film and screen printed porous layer. Beside that the influence the sol-gel titanium precursor will be presented in the aspects of the layers optical and electrical properties determined respectively by elipsometry, UV-Vis spectroscopy and electrochemical impedance spectroscopy, . This work was supported by the Polish National Science Centre under the grant No. (2014/13/N/ST8/00858)

Resume : Bismuth nanowires: electrochemical formation, structure and transport properties The systematic study of electrocrystallization from the bath containing nitrate in a mixture of ethylene glycol and water are investigated and demonstrated in work. Bismuth nanowires with diameters from 55 to 120 nm and a length of a few dozens of microns are prepared by electrodeposition into the anodic aluminium oxide and track-etched polycarbonate membranes. According to X-ray diffraction analysis and pole figures of bismuth specimens, the Bi nanowires in AAO is extremely textured, showing two orders of (11-20) reflection. SEM and HRTEM data shows that potentiostatic templated electrodeposition of Bi from water-ethylene glycol bath results in formation of high aspect ratio nanostructures with several the narrowest region. Transport properties of individual Bi nanowires were studied in a two-point geometry. In order to prevent possible contamination of Bi during the fabrication of contacts, we did not use focused ion beam. Instead of that, the contacts were fabricated using combination of electron beam lithography and magnetron sputtering techniques. The quantitative measurements of the resistivity of highly texturized Bi nanowires with diameter of ca. 100 nm and length varying from 160 to 990 nm in a temperature range from 300 to 1.2 K was applied. For all measured samples the resistance of the fragments of Bi nanowire, disposed between two Nb electrodes (Tc = 8.9 K), increases with temperature decrease, demonstrating semiconductor transport behaviour.

Resume : Organic semiconductors have increased potential interest in the last few decades for their extensive contributions in the various fields such as light emitting diodes, solar cell, non-volatile memory devices and field effect transistors etc. The most important advantages of using organic materials are mechanically flexible, light weight and low temperature processing techniques. Recently with the advancement of nanoscience and technology, one dimensional organic and inorganic nanostructure such as nanowires, nanorods, nanotube have gained incredible interests due to their very high aspect ratio and large surface area for electron transport etc. Among them self-assembled organic nanostructures like Copper, Zinc Phthalocyanines have shown good transport property and thermal stability due to their π conjugated bonds and π-π stacking respectively. Field emission properties of carbon based and inorganic nanostructures are reported in literatures mostly. But there are fewer reports in the case of field emission characteristics of organic semiconductor nanostructures. In this work, the authors report the field emission characteristics of chemically and physically synthesized Copper Phthalocyanine (CuPc) nanostructure such as nanowires, nanotube and nanotips. The as prepared samples were characterized by X-Ray diffraction (XRD), Ultra Violet Visible Spectrometer (UV-Vis), Fourier Transform Infra-red Spectroscopy (FTIR), and Field Emission Scanning Electron Microscope (FESEM) and Transmission Electron Microscope (TEM). The field emission characteristics were measured in our home designed field emission set up. The registered turn-on field and local field enhancement factor are less the 5 V/μm and greater the 1000 respectively. The field emission behaviour is also stable for 200 minute. To gain deeper theoretical understanding of the field emission phenomena at the level of nanostructures, we computationally investigated the local electric field profile of the CuPc nanostructures by a finite displacement method as implemented in ANSYS Maxwell simulation package. The computed value of enhancement factor from the simulated results is found to be in well agreement with the experimental observations. Our obtained results strongly recommend that CuPc nanostructures are major potential candidate as electron emitters for vacuum nanoelectronics and cold cathode based low power panel display applications.

Resume : Layer-engineered hybrid inorganic-organic materials have the capacity – once carefully designed and fabricated – to exhibit tailored combinations of properties traditionally seen for inorganics or organics separately, or even beyond. An elegant, yet industrially feasible way to link the inorganic and organic entities via strong chemical bonds to form coherent single-phase 2D hybrid materials is to mimic the state-of-the-art thin-film deposition technique, ALD (Atomic Layer Deposition), originally developed to deposit high-quality thin films of simple inorganic materials. For the inorganic-organic hybrids, ALD cycles are combined with MLD (Molecular Layer Deposition) cycles based on organic precursors. This enables the atomic/molecular layer-by-layer production of inorganic-organic hybrid thin films through sequential self-limiting surface reactions with high precision for the film thickness and composition. In this talk I will discuss our recent efforts towards synthesizing new functional materials by the combined ALD/MLD technique. In particular, we have fabricated oxide-organic thin-film superlattices in which the periodically introduced single/thin organic layers between oxide layers are shown to hinder phonon transport and enhance the thermoelectric properties of (Zn,Al)O and (Ti,Nb)O2 films. Also discussed are the new directions foreseen related e.g. to photoluminescence materials, Li-ion microbattery materials and so-called metal organic framework (MOF) materials.

Resume : The composite approach opens a new route for tailoring multiferroic materials through the choice of shape, size and microstructure of the constituents. This work seeks to develop and optimize new hybrid nanocomposites, which consist of inorganic ferromagnetic and organic ferroelectric two-phase components. Using rationally designed nanoscale building-blocks with properly-designed interfaces may enhance the magnetoelectric coupling between magnetic and ferroelectric component, with potential applications for new multifunctional devices. The design of these materials is based on organic-inorganic thin films built from ferromagnetic CoFe2O4 nanostripes or vertically-aligned nanowires inside a matrix of organic piezo- and ferro-electric poly(vinylidene fluoride-ran-trifluoroethylene)copolymer (P(VDF-TrFE)). In this context, two fabrication strategies are explored. The CoFe2O4 nanowires arrays are fabricated by electrodeposition of Fe2 and Co2 into supported anodic aluminum oxide (AAO) templates followed by oxidation (Figure 1-a)). The CoFe2O4 nanostripes are fabricated by electrodeposition of Fe2 and Co2 into a poly(methyl methacrylate) (PMMA) template fabricated by nanoimprint lithography, and further oxidation (Figure 1b)). The effect of the annealing treatment on the oxidation of CoFe2 nanostructures was investigated. The M(H) magnetization curves and the magnetic properties of the ferromagnetic nanostructures (coercive field, saturation magnetization, saturation field) were investigated with an Alternating Gradient Magnetometer (AGM). Finally, different fabrication strategies are being developed to embed the array of magnetic nanowires or nanostripes in a P(VDF-TrFE) layer. Ferroelectric characterization is then performed on the thin film heterostructures. In the presentation, we will focus on the fabrication methodology and provide first results on the properties of these novel hybrid layers.

Resume : Manganese oxide/poly(3,4-ethylenedioxythiophene) (MnOx/PEDOT) was anodically electrodeposited from aqueous solutions to achieve adherent nanostructured hybrid films with thicknesses and mass loadings up to 100 nm and 40 μg cm-2. When tested for oxygen reduction reaction (ORR) activity in alkaline electrolyte, MnOx/PEDOT provided improvements over MnOx only and PEDOT only control films, with > 0.2 V decrease in onset and halfwave overpotentials and > 1.5 times increase in current density. The MnOx/PEDOT film exhibited only a slightly lower reaction order than 20% Pt/C, with a more positive halfwave potential and superior electrocatalytic selectivity for the ORR upon methanol exposure. The high activity and synergism of MnOx/PEDOT towards the ORR is attributed to the intimate substrate contact and synergistic charge transfer capabilities attained by co-electrodepositing MnOx with PEDOT. Given that PEDOT has also been used in fuel cells to limit methanol crossover and as a catalyst support, and that Mn is ~ 17,000 times cheaper than Pt, MnOx/PEDOT ORR electrocatalysts could find real application in alkaline fuel cells. This work was supported by the Laboratory Directed Research and Development program at Sandia National Laboratories, a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

Resume : Supercapacitors, with fast recharge capability, long-cycle life, and high-power performance, are the most promising candidates as new electrode materials for advanced energy storage devices. In particular, faradaic supercapacitors (i.e., pseudocapacitors) are attracting a great deal of attention due to their extended working voltage and higher energy density compared to non-faradaic and hybrid supercapacitors. Typical pseudocapacitors are metal oxide/conducting polymer assemblies, whose large surface area and appropriate pore size distribution are essential properties to achieve good performance. With this contribution we introduce the use of highly-aligned TiO2 nanotube (NT) arrays, fabricated by self-organizing electrochemical anodization and coated with polydopamine (PDA), a synthetic carbon-based polymer. TiO2/PDA heterocomposites are obtained by exposing TiO2 NTs to a pH-buffered dopamine solution and the polymer thickness is controlled by adjusting coating time. We show that appropriate thermal treatment under a specific reducing atmosphere allows the formation of stable sub-stoichiometric titania and the simultaneous graphitization of the PDA top-layer, leading to a superior capacitance of the heterocomposite scaffolds with respect to pure TiO2.

Resume : Mesocrystals are superstructures of nanoparticleswithmutual crystalline order and can be intermediates in a non-classicalparticle-mediated crystallization reaction. Due to their unique architecture, they possess special features like unusual mechanical properties, high specific surface area and improved electrochemical properties. Especially in photocatalysis, mesocrystals are promising candidates since their architecture results in high inner surface area, porosity andhigh exposure of catalytically active surface facets In this contribution the synthesis of porous hybrid aerogel monolith based on multicomponent (MC) mesocrystals and cellulose fibers for photocatalytic applications will be presented. Titania-NbSbOxmesocrystalswere successfully synthesized via close control of the non-aqueous hydrolysis during MW-assisted sol-gel synthesis. Structural and chemical analysis revels the formation of MC-mesocrystals while UVVis measurements, shows improved light absorption in the visible range. Subsequently, the MC-mesocrystals were embedded in the wet gel network of cellulose polymer. After supercritical drying a highly porous hybrid monolithic aerogel with excellent mechanical properties and surface area of ~ 300 m2/g was obtained.Comparing to single phase TiO2 nanoparticles, hybrid aerogel monolith shows improved photocatalytic efficiency under solar light, mainly attributed to mesocrystals chemical composition/morphology and high porosity of cellulose network.

Resume : Separation technology is a core unit operation for the majority of chemical, pharmaceutical and food industry. Membrane technology could form a sustainable alternative and/or complementary separation technology, reducing energy and waste but also allowing otherwise difficult separations under mild conditions. Two key performance indicators for ceramic membranes are their structural properties in combination with their surface chemistry. Hence, both 1) the synthesis of the selective toplayer from solution and its stability during thermal treatment and the 2) adjustment of the surface properties via post-treatments are crucial to tailor the selectivity of separation and flux of the membranes towards applications. Both aspects will be discussed. Recently, adding an extra dimension of chemical recognition and interaction to ceramic membranes is getting increasing attention. To implement affinity based separation in ceramic membranes, organic surface modification is being applied. In addition to the existing organophosphonic acid surface modification, hybrid organic-inorganic membranes have been jointly developed by VITO and UAntwerpen based on Grignard chemistry. This new method results in unique features at the top layer, creating new opportunities. The span of control, advantages and drawbacks of tailoring structural features and surface properties will be compared with respect to membrane filtration as well as an outlook to other applications such as protein immobilisation.

Resume : Precipitation of zinc oxide by thermal destabilization of amminocomplexes was used to coat textiles made of natural or synthetic fibers. This low temperature (<80°C) process is easy to scale-up and cheap. Its reactivity can be controlled by the knowledge of thermodynamical constants at different temperatures. Very dense coverage by rod-like or flower-like structures, exhibiting a multi-scale architecture from the nano to the micro level, can be obtained by tuning physico-chemical and process parameters. We will show and explain the effects of the main parameters as the chemical nature of the fibers, zinc and ammonia concentrations, temperature, the heating technique (by the walls or by microwave irradiation), the choice of closed or open vessels, the choice of batch or continuous systems... Such functionalized substrates may be used for photocatalytic depollution/decontamination and some tests will be shown. Zinc oxide is known to be chemically much less stable than titanium dioxide, but it is also much less expensive and we will show results about the degradation of functionalized textiles in different conditions and their regeneration, in order to assess the soundness of this concept of low-cost and regenerable photocatalytic textiles.

Resume : All-solid-state batteries (ASSBs) are energy storage systems, where solid electrolytes (SEs) are substituted for the commonly used liquid electrolytes. At the moment, the most promising SEs are sulfides, like Li7P3S11, and glasses prepared from Li2S and P2S5. They usually show ionic conductivities in the range of 10-4 to 10-3 S/cm and exhibit low or zero grain boundary resistances. Nevertheless, if they are in direct contract with cathode materials at high potentials, such as Li1-xCoO2 (LCO), the formation of a so called “space-charge layer” can be observed, resulting in lithium depletion of the SE at the interface between the materials. Here, we demonstrate the beneficial role of oxide thin films as protective surface layers in ASSBs. They were simply coated onto the cathode material through facile sol-gel methods, in order to prevent the detrimental lithium depletion mentioned above. In particular, we focus both on the electrochemical performance of LCO with and without LiNbO3 and in combination with various SEs (glasses of different composition and Li7P3S11) and on the characterization of the surface coating. ASSBs using coated cathode material exhibit significantly enhanced cycling stability.

Resume : Subwavelength micro-structured surfaces are often used as antireflection and light-trapping structures whose main optical based applications concern solar energy and efficiency improvements of existing products (Photovoltaic cells and modules, …). The authors demonstrate here a unique low cost process to print directly TiO2 gratings on both planar surfaces and cylindrical components. Furthermore, TiO2 offers interesting optical properties, good mechanical and chemical stability and thus can be directly used as a functional photocatalytic microstructure. A specific sol–gel formulation has been adapted from titanium isopropoxyde orthotitanate (TIPT) complexed by benzoyl acetone (BzAc) in alcoholic solvent. Easily deposited by spin or dip coating to form a thin xerogel layer, it creates under UVA exposition, a contrast of solubility between illuminated and non-illuminated areas to achieve direct microstructuring like a negative photoresist. A mono layer of silica microspheres of 1 µm diameter deposited by Langmuir Blodgett process on the photosensitive xerogel layer has been illuminated by a collimated source emitting at 365 nm wavelength. Each silica microsphere acts as a convergent super-lens, focusing the light to create a so-called photonic nano-jet beam propagating in the TiO2 underlying photoresist layer. After washing in solvent, nanopillars are revealed. The authors will present the chemistry of the sol-gel process, modeling of the electric field distribution underneath the spheres during the illumination process with the RCWA method (Rigorous Coupled Wave Analysis) and preliminary results of hexagonal TiO2 nano-pillars fabrication on planar and cylindrical substrates.

Resume : Amongst the various metal oxides nanostructures, CuO is one of the most widely investigated for applications ranging from energy storage, catalysis, sensing and magnetic. In a very recent paper, it was proposed that hollow structures of CuO has nearly 10 times higher catalytic activity than solid particles of similar dimensions. In this work, we clearly show that the catalytic activity of CuO can be even higher than that of hollow structures if the morphology is carefully tuned further. The growth mechanism of the particle/structure leads to a high effective surface area that synergically contributes in the properties that are dependent on the surface states. CuO nanoflakes, synthesized using the precipitation method, shows an enhanced catalytic conversion of p-nitrophenol to p-aminophenol in presence of NaBH4 with a reaction rate constant of 4.87 x 10-2 s-1. The observed catalytic rate constant for CuO nanoflakes is much higher than that reported for solid or even hollow nanostructures. The magnetic measurement of the CuO nanostructures also shows higher ferromagnetic response, when compared to solid and hollow nanostructures.