Synergistic Effect of Sodium Cyanoborohydride in Pb-Sn Perovskite Solar Cells

Abstract

Pb-Sn mixed perovskite has received extensive attention because of its high research value in environmental protection and theoretical prospects. However, the film defects brought on by the quick crystallization of Pb-Sn mixed perovskites and the facile oxidation of Sn2+ to Sn4+ are detrimental to the performance of Pb-Sn perovskite solar cells (PSCs). Here, aiming at the interface of Pb-Sn PSCs, which has been less studied, a reducing agent is first introduced on the top of Pb-Sn mixed perovskite interface. The results show that in NaBH3CN(SC), B─H can suppress the oxidation of Sn2+ and C≡N can enhance the perovskite crystallinity and passivate the surface defects. Benefitting from this synergistic effect, a champion power conversion efficiency of 21.3% is obtained for Pb-Sn PSCs. In addition, the encapsulated device can maintain good stability under maximum power point tracking conditions.