Band alignment at Sb2S3 Cu In,Ga Se2 heterojunctions and electronic characteristics of solar cell devices based on them

Band offsets at Sb2S3 Cu In,Ga Se2 heterojunctions have been studied by x ray and ultraviolet photoemission spectroscopy. The valence and conduction band offset have been estimated to 0.6 0.3 eV and 0.2 0.3 eV , respectively. This result suggests Sb2S3 as a potential buffer layer material for chalcopyrite based solar cells. However, Cu In,Ga Se2 Sb2S3 ZnO solar cells have been investigated. While the open circuit voltage ranged up to amp; 1011;0.4 0.5 V, the short circuit current was limited to amp; 1011;1.8 4.9 mA cm2. A photocurrent of about 30 mA cm2 was found for negative bias. On the basis of bias dependent quantum efficiency measurements and calculations, limiting mechanisms are discussed