Imidazole Derivative Assisted Crystallization for High‐Efficiency Mixed Sn–Pb Perovskite Solar Cells

Abstract Mixed Sn–Pb perovskites with narrow bandgaps and high optical absorption coefficients are promising photovoltaic materials. However, the easy oxidation of Sn 2+ and fast crystallization of mixed Sn–Pb perovskites still limit the efficiency of mixed Sn–Pb perovskite solar cells (PSCs). Here, an imidazole derivative 2‐(Aminomethyl)imidazole dihydrochloride (2‐AD) to suppress the oxidation of Sn 2+ and improve the perovskite film quality through coordination with Sn 2+ /Pb 2+ ions is introduced. The optimized devices show a high power conversion efficiency of 22.31% with outstanding long‐term illumination stability. This work provides an effective strategy to achieve efficient and stable mixed Sn–Pb PSCs.