Novel semiconductor CIGS photovoltaic material and thin-film ED technology

In order to achieve low-cost high-efficiency thin-film solar cells, a novel semiconductor Photovoltaic (PV) active material uIn1-×Ca×Se2(CIGS) and in-film Electro-Deposition (ED) technology is explored. The experimental processes of CIGS/Mo/glass structure using the novel ED technology and the results are reported. The results show that high quality CIGS polycrystalline thin-films can be obtained by the ED method, in which the polycrystalline CIGS is definitely identified by the (112), (204, 220) characteristic peaks of the tetragonal structure, the continous CIGS thin-film layers with particle average size of about 2 μm of lwnfrh NS eouns 1.6 μm of thickness. The thickness and solar-grade quality of CIGS thin-films can be produced with good repeatability. Discussion and analysis on the ED technique, CIGS energy band and sodium (Na) impurity properties were also performed. The alloy CIGS exhibits not only increasing band-gap with increasing x, but also changing material properties that is relevant to the device operation. The beneficial impurity Na originating from the low-cost soda-lime glass substrate becomes one prerequisite for high quality CIGS films. The novel material and technology are very useful for low-cost high-efficiency thin-film solar cells and other devices.