With multiple groups reporting efficiencies over 15% for small-area CuInSe2 (CIGS) photovoltaic cells, the challenge now facing the photovoltaics industry is to bring the efficiencies of small-area cells and large-area industrial modules closer together. However, yield and reproducibility, particularly in large numbers and over large areas, remains problematic. This project will improve the manufacturability of CIGS-based solar cells by developing co-sputtered CuInSe2 (CIS) absorber layers. Co-sputtering should provide good control and scalability of the fluxes to the CIS layer, while maintaining essentially the same film growth and quality achieved in co-evaporated films. Phase I will establish reliable film composition by monitoring each sputtering target with optical emission spectroscopy, evaluate the CIS film structure obtained from a two-stage co-sputtered process, determine the best method of Se delivery and control, control the sputter flux distributions, investigate ion bombardment effects in the growing film, and model a large-scale deposition system.
Commercial Applications and Other Benefits as described by the awardee: The process should lead to improvements in the manufacturability and therefore cost of CIS-based modules. Off-grid and mobile power applications stand to benefit immediately. A cleaner environment, increased national energy independence, and cheaper power are long-term benefits.
