Unique High Temperature Liquid Crystal Polymer Substrate for Thin Film Solar Cells

"Thin film solar cells have promise of producing high specific power values (over 1000W/kg) if a light weight substrate that permits growth of high-quality semiconductor material is available. Past results using CuInSe2 -type materials on polymersubstrates have suffered because the CIGS quality has been low due to the limitations on growth temperature imposed by the thermal properties of the polymers used. Cells of CIGS on metal foils have suffered from the problems of the substrate's highdensity and high conductivity which prevents integrated interconnects.Foster-Miller proposes using PBO, which has been shown to have a useful temperature in vacuum approaching 600¿C. This is comparable to the maximum temperature for the soda lime glass used as a substrate in the highest efficiency devices. The PBOsubstrate should enable CIGS deposition at a temperature high enough to yield high-quality material for high-efficiency solar cells. The high mechanical strength of PBO allows use of a very thin substrate film, which allows for very high specific powervalues at low cost. Phase I will document solar-cell material quality versus growth temperature, evaluate PBO as a substrate, and document potential problems; samples of CIGS on PBO will be furnished for evaluation. (P-020264) Commercial prospects for CIGS-type cells on PBO are excellent. PBO can be supplied as long, large-area rolls to permit continuous processing and monolithic integrati