CIGS module development on flexible substrates

Advances in module efficiency and process control using CIGS-based PV on flexible substrates are described. Modules on thin webs of stainless steel foil (SST) and polyimide (PI) have been made using continuous roll-to-roll (RTR) processing in compact reactors. Process control improvements for many important parameters have been instituted, including in-situ X-ray fluorescence and real-time Se delivery regulation; these have resulted in dramatic increases in uniformity and reproducibility for both substrate types. For polyimide substrates, several material limitations and previously reported difficulties such as back contact cracking, poor absorber adhesion and low temperature processing are addressed. Successful development of a low-loss, all-laser scribing process for monolithic integration on polyimide is described.