Study of CuxTe Polycrystalline Thin Films for CdTe Solar Cells

Cu_xTe polycrystalline thin films were prepared by co-evaporation method. The influence of the film characteristic on the CdS/CdTe photovoltaic device performance was investigated. The results show that asdeposited Cu_xTe thin films are amorphous phase. While after annealing, samples were polycrystalline phases with increasing temperature. Especially, when N_Cu:N_Te was 1:1.44 the film showed more evident polycrystalline phase and the crystallization degree increased. Furthermore, Cu and Te elements of the annealed films form ions from XPS analysis. The C-V, I-V characteristics indicate that the CuTe buffer layers eliminate the Roll Over phenomenon. Meanwhile, the back contact properties, such as the diode characteristics (A) of the forward junction and the dark saturation current density (J_sc) have been improved. As a result, the conversion efficiency is improved by 14.5%, from 10.3% to 12.667%.