أفلام رقيقة

Résumé: Thin films of metal oxides/polymers nanocomposites were deposited on glass substrates by Spin-Coating and Dip-Coating techniques. The nanocomposites were elaborated by inserting, in the matrices of polystyrene (PS) and polyvinyl chloride (PVC) polymers, of nanoparticles of metal oxides such as copper oxide (CuO) and lead oxide (PbO). The nanoparticles of semiconductor CuO and PbO were synthesized beforehand by the hydrothermal method. The xray diffraction characterization of the obtained powders have revealed a monoclinic phase for CuO crystallites and an orthorhombic phase for PbO. The size of the crystallites of the two semiconductors is of a nanometic order. Calcul the of gap energy indicate a shift towards high energies compared to massive crystals. This shift is due to the effect of the quantum confinement induced by the nanometric size of the crystallites of the semiconductors. These nanocrystals are used for the preparation of the nanocomposites of CuO/PS, CuO/PVC, PbO/PS and PbO/PVC by simple insertion of CuO and PbO nanoparticles in the PS and PVC polymers. The analysis of the elaborated nanocomposites by X-ray diffraction has allowed to notice the incorporation of the CuO and PbO crystallites into the PS and PVC polymers matrixes and analysis by Raman and infrared spectroscopies has confirmed the presence of CuO and PbO crystallites in the PS and PVC matrixes by revealing specific vibration modes to the Cu-O and Pb-O bonds. The surface morphology and topography of thin films of nanocomposites were highlighted with the help of atomic force microscopy (AFM) and have shown homogeneous dispersion of CuO and PbO crystallites and a low surface roughness. the characterization by measurement of the optical absorption in the UV-Visible domain allows to observe the increase in optical absorption which is attributed to CuO and PbO nanocrystallites because PS and PVC are optically transparent in the UV-Visible domain. A shift of the gap energy of the nanocomposites compared with the gap energy of the pure polymers and the massive crystallites of CuO and PbO was observed. This variation in gap energy is the result of the new optical behavior of the prepared nanocomposites. The optical characterization by the measure of the photoluminescence has shown that the elaborated samples present intense luminescence bands in the visible range, hence the possibility of consider these matrices as optically active media and can be used for the making devices of specific optics properties.

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