Elaboration et Caractérisation de Couches Minces de Cu(In,Ga)(Se,S)2 destinées au Photovoltaïque

Abstract

Solar cells based on thin films of Cu(In,Ga)(Se,S)2 compounds prepared by vacuum deposition have attained significant conversion efficiencies. In order to reduce production costs, other deposition techniques are being considered. One of them, already used on at an industrial scale, is the electrodeposition method. In this work, we describe how CuIn(Se,S)2 thin films were synthesized using a one-step electrodeposition process from a single electrolyte bath containing the metal salts of the constituents (Cu, In, Se and S). The thin films were deposited on glass substrates coated with fluorine doped tin oxide (FTO). Cyclic voltammetry was used to optimize the electrochemical deposition parameters such as pH, salt concentrations, complexing agent, and deposition potential. A few films have undergone post-annealing treatment in a vacuum atmosphere at a pressure of 10-6 mbar at the temperature of 300°C for one hour. Characterization techniques used in this study were X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy (SEM), atomic force microscopy (AFM), and UV-Visible absorption spectroscopy. The characterization results show that the films have a good morphology, a good crystal structure, a high absorption coefficient close to the fundamental edge and a band gap energy of 1.44 eV. These properties are suitable for high efficiency solar cell applications