High-performance flexible lead-free perovskite solar cells based on tin-halide perovskite films doped by reductant metal halide

The lead-free perovskite solar cell could break the limit of the toxicity of lead. However, the oxidation of Sn2+ limits the performance of Sn-based perovskite solar cells. Here, we replied the reductant metal halide as reducing agent in perovskite film, efficiently suppressing the oxidation of Sn2+. Based on the high quality FA0.8MA0.2SnI2.8Br0.2 film with 0.10 M FeCl2, a flexible lead-free perovskite solar cell device was obtained with PCE of 5.24%, and it could maintain 50% of initial PCE after half a year of storage in the N2 glovebox.