Mixed‐Organic‐Cation Tin Iodide for Lead‐Free Perovskite Solar Cells with an Efficiency of 8.12%

Abstract In this work, a fully tin‐based, mixed‐organic‐cation perovskite absorber (FA) x (MA) 1− x SnI 3 (FA = NH 2 CH = NH 2 + , MA = CH 3 NH 3 + ) for lead‐free perovskite solar cells (PSCs) with inverted structure is presented. By optimizing the ratio of FA and MA cations, a maximum power conversion efficiency of 8.12% is achieved for the (FA) 0.75 (MA) 0.25 SnI 3 ‐based device along with a high open‐circuit voltage of 0.61 V, which originates from improved perovskite film morphology and inhibits recombination process in the device. The cation‐mixing approach proves to be a facile method for the efficiency enhancement of tin‐based PSCs.