Enhancing the efficiency of air-processed (Cu, Ag)2ZnSn(S, Se)4 solar cells by regulating the band tail and interface recombination

Air-processed kesterite solar cells show excellent prospects for commercial application because they are suitable for large-scale production. This study shows how the power conversion efficiency (PCE) of (Cu, Ag) 2 ZnSn(S, Se) 4 solar cells can be improved by adjusting the annealing time during the selenization process at a low temperature of 70 °C. Enhancement of PCE is achieved when the annealing time is 240 s. The primary determinant of enhanced PCE is a reduction in reverse saturation current density (J 0 ) and ideality factor (A). Examination of depth characterization indicated that the decrease in J 0 and A can be ascribed to the inhibition of [2Cu Zn  + Sn Zn ] defects cluster, which is mainly accountable for the band tail states, and the suppression of interface recombination .