Interfacial modification mechanism by aging effect for high-performance Cd-free and all-dry process Cu(In,Ga)(S,Se)2 solar cells

Abstract

Modification of the hetero-junction interface in Cd-free and all-dry process Cu(In,Ga)(S,Se)2 (CIGSSe) solar cells by introducing the aging process for the bare CIGSSe films is demonstrated, ultimately achieving the highest conversion efficiency of 22.0%. In this article, two positive effects of the aging process are discussed. First, additional phases, such as Inx(O,S)y and Cu-deficient phases, are naturally formed on the CIGSSe surface. Second, unintentional segregation of Zn-rich particles at the (Zn,Mg)O/CIGSSe interface during the (Zn,Mg)O deposition is suppressed. These effects lead to the reduction of recombination at the hetero-junction interface and dramatic enhancement of performance for the Cd-free and all-dry process CIGSSe solar cells.