Serological Investigation of Bluetongue Virus Infection by ELISA in Sentinel Cattle Herds in Tunisia

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Silicon nanowires in polymer nanocomposites for photovoltaic hybrid thin films

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Influence of the silicon surface treatment on the properties of SiNWs/PVK hybrid solar cells

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Electrical, optical and morphological properties of a new chromogenic calix[4]arene derivative

International audienceWe have studied electrical properties of ITO/azo-calix[4]arene/Al diodes by means of current voltage measurement and impedance spectroscopy in a wide frequency range. The devices with an ITO/azo-calix[4]arene/Al structure could be modeled as a simple combination of resistors and capacitors. The impedance spectra can be discussed in terms of an equivalent circuit model designed as a parallel resistor R-p and capacitor C-p network in series with resistor R-s. We extract numerical values of these parameters by fitting experimental data. Relaxation processes have been identified too from the impedance spectroscopy. Their values deduced from fitting experimental data to the model have given a dielectric relaxation time in the ms range and an exponential trap distribution

Analytic model for organic thin film transistors (OTFTs): effect of contact resistances application to the octithiophene

Thin film organic field-effect transistors were grown with vapor-deposited polycrystalline-octithiophene on silicon oxide insulating layers. This component requires an ohmic source and drain contacts for ideal operation. The performance of organic electronic-devices is often limited by injection. In many real situations, however and specifically in organic devices, the injection of charge carriers from metals into semiconductors is non-linear. This has an adverse impact on the performance of thin film transistors, and makes the analysis of electrical measurements a complex task because contact effects need to be disentangled from transistor properties. This paper deals with the effects of non-ohmic contacts on the modeling of organic transistors and gives specific rules on how to extract the real transistor parameters using only electrical measurements. Several methods are used in order to study the influence of the contact resistance on the performance of organic transistors. This influence appears especially on the current-voltage characteristics of organic field effect transistor. We present a first method used to extract the key parameters of OFET such as; mobility, threshold voltage and contact resistances using the fit of the transfer characteristic of the devices. The second method has been used to exploit the different functional dependences of current on gate voltage which is induced by the presence of contact resistances in the linear and in the saturation regimes. All electrical key parameters of OFETs based on octithiophene have been extracted and we demonstrate that both mobility and contact resistance depend on gate voltage and temperature

Extraction of different parameters of hybrid solar cell based on PVK/Silicon nanowires

International audienceSolar cell based on conjugated polymer inorganic semiconductor are often designed to be structured in hybrid solar cell in objective to supply a large interface area for exciton dissociation. The main objective of this paper is to extract four electrical parameters such as the saturation current, the series resistance, the ideality factor and the shunt resistance from the measured current voltage characteristics in different conditions of annealing temperatures, annealing times, the weight ratio of Silicon nanowires, the thickness of photoactive layer and the treatment of Silicon nanowires with a fluorhydric acid solution HF for which hybrid solar cell had the best electrical properties. These parameters are extracted to simulate the current voltage of solar cell based on a thin film blend of Poly (N-vinylcarbazole) (PVK) and Silicon nanowires (SiNliVs). A good agreement between theoretical model and experimental measurement of electrical characteristics is obtained which illustrates the improvement that can supply the variation of different conditions on the characteristics of solar cells based on PVK/SiNWs

Structural and optical investigation of (V, Al) doped and co-doped ZnO nanopowders: Tailored visible luminescence for white light emitting diodes

International audienceThis paper deals with co-precipitation synthesis and characterization of undoped, Al, V doped, and (Al+V) co-doped ZnO nanopowders. Complementary techniques are used: X-ray diffraction (XRD), transmission electron microscopy (TEM), diffuse reflectance and photoluminescence (PL) spectroscopies. XRD analysis revealed the formation of hexagonal-wurtzite structure for all samples. The average crystallite size decreases from 40 to 20 nm by doping ZnO NPs. TEM images showed quasi-spherical shaped nanoparticles. The UV-visible absorption spectra revealed that doping and co-doping induce slight red-shift of gap energy (3.29eV-3.27eV). The Urbach energy increases mainly with V doping, suggesting an increase in disorder and defects levels. PL spectra exhibit narrow and wide emissions in UV and visible regions respectively. Gaussian deconvo-lution of the broad visible peaks revealed several overlapped emissions. Mainly V incorporation in ZnO (single and double doping) notably improves visible luminescence. It leads to widening of the visible emission from 460 to 585 nm

Impact of surfactants covering ZnO nanoparticles on solution-processed field-effect transistors: From dispersion state to solid state

International audienceSolution-processed n-channel oxide semiconductor thin-film transistors (TFTs) were fabricated using zinc oxide (ZnO) nanoparticles. The solution-processable semiconductor dispersions based on ZnO were prepared by dispersing the synthesized ZnO nanospheres in solution. The dispersion state was strongly affected by either the surfactant type or the solvent nature. Two small organic molecules commercially available, ethanolamine (EA) and benzoic acid (BA), were used as surfactant in alcohol solvent. The introduction of EA reduced the size of nanocrystal agglomerates and improved their dispersion properties simultaneously. Spin-coating of EA-modified ZnO dispersion following by a low-temperature annealing produced uniform polycrystalline nanoparticulate thin films. The resulting solid state of thin films demonstrated that the incorporation of EA has not a direct impact on the morphology but slightly decrease the field-effect mobility by less than one order of magnitude due to the insulating properties of EA organic molecules grafted on ZnO particles. As contrary, BA generated the existence of large-size cohesive ZnO agglomerates in solution which persist in the solid state to generate a less efficient charge transport. The modification of the particles surface by capping agent and the resulting particle-particle interactions in thin films were attributed as the main factors to impact on the field-effect mobility. To surfactant-free dispersions, the cohesive forces in ZnO agglomerates have been strongly influence by the solvent nature for a balance between a suitable dispersity of solution state and an effective solid state to charge transport. (C) 2016 Elsevier B.V. All rights reserved