Constructing A Carrier Collection Framework at The Rear Interface in Cu2ZnSn(S, Se)4 Solar Cells by Selenizing an Inserted CuBi2O4 Nanolayer

Abstract

This work introduces the application of an ultrathin CuBi₂O₄ (CBO) nanolayer to improve the performance of Cu₂ZnSn(S, Se)₄ (CZTSSe) photovoltaic cells. The CBO layer is situated between molybdenum (Mo) and the CZTSSe absorber, which promotes the formation of a more compact absorber layer and larger CZTSSe grain sizes. Furthermore, the decomposition of the CBO layer during high-temperature annealing leads to the formation of Cu-doped bismuth selenide in the bottom region of the absorber. The Cu-doped bismuth selenide improves carrier transport and enhances the electrical properties at the rear interface of the CZTSSe device. These enhancements lead to notable improvements in all key photovoltaic parameters, thereby boosting the overall efficiency of the solar cell.