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

The poor crystal quality inside an absorber layer and the presence of various harmful defects are the main obstacles restricting the properties of Cu₂ZnSn (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 Cu₂Zn(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.