Defect Passivation for Production-Quality and High-Bandgap CIGS and CIAS Solar Cells

A major factor that detracts from the many advantages offered by thin-film flexible CIGS PV for non-terrestrial applications is that it currently provides substantially lower solar conversion efficiencies than crystalline PV technology. While CIGS device efficiencies exceeding 19% have been produced in the laboratory, efficiencies of devices produced in large-scale production have been substantially lower. Recent work has identified the presence of electronic atomic-level defects in the CIGS material as a primary factor responsible for the gap between laboratory and production efficiencies. Also, the drop-off in efficiencies with increasing bandgap has been attributed to a higher density of defects serving as recombination centers or a higher sensitivity to such defects. Such defects must be eliminated or passivated to achieve the potential of CIGS technology. While all manufactures of CIGS have put considerable effort into minimizing formation of defects through optimizing process parameters, another approach to controlling defects is to "passivate" them by adding constituents that eliminate their electronic activity or alter it in a way that reduces the detrimental effect. ITN Energy Systems, Inc. proposes to conduct a thorough study of defects and potential defect passivation methods in production-quality CIGS and high-bandgap CIGS and CIAS (copper-indium-aluminum-diselenide).