Silicone-Resin Free Standing High-Temperature Films for Monolithically-Integrated CIGS Devices

ITN Energy Systems, Inc. is developing a space photovoltaic (PV) product based on our commercialization partner, Global Solar Energy, Inc.'s (GSE) flexible thin-film polycrystalline copper-indium-gallium-diselenide (CIGS) technology. These devices arebeing made as discrete cells on metallic foil substrates, as well as a monolithically integrated device on a polymeric substrate. While we have demonstrated a cell efficiency over 11% on a polyimide (PI) substrate, the record efficiency of 18.8% asmeasured at the National Renewable Energy Laboratory (NREL) was deposited on a rigid glass substrate, and approaching 18% on a flexible stainless steel foil substrate. The polyimide substrate has limited high temperature capability, and consequentlyrestricts CIGS PV material quality, while the stainless steel foils are a source of impurities, have rough surfaces, and do not enable space saving monolithic integration. ITN has teamed with Dow Chemical Corp. to develop insulating substrates based onSi-resin compounds. These substrates can achieve processing temperatures above 500¿C while providing an electrically insulated substrate to facilitate monolithic integration. ITN is developing two potential substrate schemes: Si-resin based insulators onmetal foil, and free-standing Si-resin based insulator films. The best performing substrates will be utilized in Phase 2 to demonstrate monolithically-integrated PV modules and scale-up.