Synergistic Effect of Ag, Sb Dual‐Cation Substitution on Cu2ZnSn (S, Se)4 High‐Efficiency Solar Cells

ABSTRACT The poor crystal quality inside an absorber layer and the presence of various harmful defects are the main obstacles restricting the properties of Cu 2 ZnSn (S, Se) 4 (CZTSSe) thin‐film solar cells. Cation doping has attracted considerable research attention as a viable strategy to overcome this challenge. In this paper, based on Sb‐substituted CZTSSe system, we prove that Ag partially substituting Cu may be a feasible strategy. After a series of characterization of the films, it was discovered that the crystal quality and crystallinity of the films were further improved by introducing Ag into Cu 2 Zn(Sb, Sn) (S, Se) 4 (CZTSSSe), and the concentrations of Cu Zn accepter defects and 2[Cu Zn + Sn Zn ] defect clusters were effectively inhibited. At the same time, the carrier concentration is increased. The results show that when the Ag doping ratio is 15%, the photovoltaic conversion efficiency (PCE) reaches 8.34%, compared with the single‐doped Sb element, the efficiency is increased by 24%. For the first time, this study investigates the collaborative effect of Sb, Ag dual‐cation substitution in CZTSSe. The solar cell performance enhancement mechanism offers new potential for the advancement of CZTSSe thin‐film solar cell technology in the future.