Stabilization of Inorganic CsPb 0.5 Sn 0.5 I 2 Br 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.