Traces of iron impurities in copper sources can be a poison to Cu(In, Ga)Se2 solar cells

Abstract

Abstract It has been widely accepted that the diffusion of iron from stainless steel substrates has detrimental impact on Cu(In, Ga)Se2 (CIGS) solar cell performance. However, the effect of traces of iron impurities in copper sources can be neglected all the time. In this work, 99.97% purity copper which contains only 0.03% iron was used to fabricate CIGS devices. Compared to the copper of 99.99% purity, it has been showed that this 0.03% difference in purity can lead to a 70% efficiency improvement for CuGaSe2 (CGS), 35% efficiency improvement for normal band gap CIGS, and 29% efficiency improvement for narrow band gap CIGS. These results revealed that traces of iron impurities in copper sources can be a fatal poison to CIGS solar cells.

Keywords

• CIGS
• copper sources
• impurities
• solar cells