Efficient flexible Mo foil-based Cu2ZnSn(S, Se)4 solar cells from In-doping technique

Cation substitution has an important impact on the power conversion efficiency (PCE) of Cu 2 ZnSn(S,Se) 4 (CZTSSe) solar cells. Herein, a significant PCE enhancement of flexible indium-doped CZTSSe solar cells has been achieved by partially substituting Sn 4+ with In 3+ . Systematic measurements indicate that In doping in CZTSSe film effectively improves the crystallinity and carrier concentration of the absorber layer . Meanwhile, the treatment reduces interface recombination and band tailing by passivating deep defects and increases the open-circuit voltage ( V oc ) of the solar cells. By physical analysis, the key parameters for the solar cell diode such as A , J 0 , R s and R sh are significantly improved after In-doping, indicating better PN junction quality. Under the optimal In-doping (x = In/(Sn + In) = 9%), the flexible Cu 2 ZnSn 1- x In x (S,Se) 4 solar cell has been successfully obtained with the best efficiency of 7.19% and the V oc enhancement of 62 mV due to reduced V oc deficit and band tailing.