Browsing by Author "Hatem, Djedjiga"

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    Structures électronique à base de matériaux organiques pour application aux cellules solaires photovoltaïques
    (Université Mouloud Mammeri, 2013-12-05) Hatem, Djedjiga
    The amelioration of the efficiency of photovoltaic conversion in organic solar cells can be obtained by minimizing losses in reflection and absorption in the transparent electrode/active layer interface involving increased absorption efficiency in the active layer which can be achieved by the use of TCOs with special optical and electrical properties. Tin oxide SnO2 thin films have been prepared by APCVD method using the SnCl2 as a starting material. The surface morphology of the films deposited on glass substrates were investigated by scanning electron microscopy (SEM).The ellipsometry was used to determinate the refractive index for the films deposited at 480°C and the resistivity was measured using Hall effect measurement. Transmittance of SnO2 films deposited on ITO was measured by UVvisible spectroscopy. SnO2 films prepared during 11 minutes present a sheet resistivity of 7,6.10 -5 ?cm, transmittance higher than 80% and refractive index of 1.75 can be used as interfacial layer in organic solar cells application to minimize the eflectivity. SnO2 films can be used as interfacial layers in inverted solar cells application as an interfacial layer to improve the efficiency and stability. Titanium oxide TiO2 thin films have been prepared by APCVD method using the TiCl4 as a starting material. The surface morphology of the films deposited were investigated by scanning electron microscopy (SEM).The ellipsometrywas used to determinate the refractive index for the films deposited at 490°C and the resistivity was measured using Hall effect measurement. Transmittance of TiO2 films deposited on ITO was measured by UV-visible spectroscopy. TiO2 films prepared during 5minutes present : a resistivity of 4,210 -4 ?.cm, transmittance higher than 80% and refractive index of 1,8 can be used as interfacial layer in organic solar cells application to minimize the reflectivity. TiO 2 films can be used as interfacial layers in inverted solar cells application to improve the efficiency and stability. The use of TCOs in organic solar cells pplication requires deposition at low temperatures and with a limited heat treatment. This process results in high resistivity materials. To achieve practical resistivity levels, we need to replace the conventional electrode with an TCO/Metal/TCO tri-layer anode. This material yielded the desired electrical properties without a significant effect on its optical properties. For example, a sheet resistance of 15 ?/? and an optical transmission of 90% were obtained for a tri-layer film in which thickness of each ITO layer is 50 nm and the Ag layer thickness is 8 nm. The use of these trilayer anodes in organic solar cells led to the modification in optical field distribution in the structure of the solar cells, and improve the external power conversion efficiency by maximizing the absorption into the photoactive layer.