Enhanced performance of tin halide perovskite solar cells by addition of hydrazine monohydrobromide

摘要： Although tin-based perovskite has been considered as a kind of potential environmentally-friendly photovoltaic materials, the tin-based perovskite solar cells are limited due to their poor stability and low conversion efficiency mainly tracing to the oxidation from Sn2t state in tin-based perovskite films. Herein, a facile reductive approach is developed to suppress the oxidation, in which tiny amount of hydrazine monohydrobromide is doped into FASnI3-based perovskite precursor solution as a reducing agent. Our results demonstrate that the addition of hydrazine monohydrobromide could reduce the defects and trap states in perovskite by inhibiting formation of tetravalent tin, and increase the open circuit voltage by widening the bandgap of perovskite. As a consequence, the best optimized perovskite solar cell achieves an excellent power conversion efficiency of 7.81%, which represented a 39.5% improvement compared to the best reference device. The optimized devices display stabilized power output near the maximum power point and negligible hysteresis effect.