Decreased interface defects in Cu2ZnSn(S,Se)4 solar cells via Cd2+&Ag+ double-ion interface deposition

Kesterite Cu₂ZnSn(S,Se)₄ (CZTSSe) thin film solar cells are considered a promising new type of film cell, due to their rich elemental reservation and excellent photovoltaic performance. However, the deleterious defects at the heterojunction interface severely hinder charge transport, separation, and extraction, significantly limiting the photovoltaic performance of CZTSSe solar cells. In this study, a simple method involving the incorporation of Cd²⁺ and Ag ⁺ dual-ion at the heterojunction interface was proposed to reduce interfacial defects. The results showed that Cd²⁺ and Ag ⁺ dual-ion interface deposition effectively reduced the [2Cu_zn + Sn_zn] harmful defects near the heterojunction interface and subsequently reduced the number of recombination centers in the interface. This led to improved carrier recombination at the interface. Meanwhile, the devices achieved a wider depletion width, which was more favorable for carrier collection. Ultimately, the conversion efficiency increased by 32.81 %. This simple interface dual-ion deposition strategy offers a promising strategy for further enhancing the efficiency of CZTSSe cells.