Stabilization of Inorganic CsPb0.5Sn0.5I2Br Perovskite Compounds by Antioxidant Tea Polyphenol

Implementation of inorganic perovskite compounds and reduction toxicity of lead are important for developing sustainable and renewable photovoltaic power generation. The inorganic Pb/Sn binary metal halide perovskites offer a perfect opportunity for tuning optical bandgap and thus hold significant potential in emerging technologies such as solar cells. However, an easy oxidation of Sn 2+ to Sn 4+ has become one of the main issues for achieving efficient and stable Sn‐based perovskite solar cells (PSCs). Herein, an effective method for stabilizing CsPb 0.5 Sn 0.5 I 2 Br is proposed to realize high‐efficiency PSCs via antioxidant tea polyphenol (TP). It is found that TP can not only slow down the oxidation of Sn 2+ but also regulate perovskite film crystallization during the formation of perovskite films via coordination interaction, leading to a reduced density of defects and an enlarged open‐circuit voltage. The resultant perovskite solar cell using CsPb 0.5 Sn 0.5 I 2 Br (TP) with an all‐inorganic mesoscopic framework of FTO/c‐TiO 2 /m‐TiO 2 /Al 2 O 3 /NiO/carbon achieves an impressive power conversion efficiency of 8.10% with high stability.