Optimization of Stable Quasi-Cubic FAxMA1–xPbI3 Perovskite Structure for Solar Cells with Efficiency beyond 20%

Abstract

Complex compositional engineering of mixed halides/mixed cations perovskites has recently fostered a rapid progress in perovskite solar cell technology. Here we demonstrate that when 10% of formamidinium (FA⁺) is simply added into methylammonium lead iodide (MAPbI₃) a highly crystalline and compositionally uniform perovskite is formed, self-organizing into a stable “quasi-cubic” phase at room temperature. We reached power conversion efficiency of over 20.2%, the highest value reported to date for FA_xMA_1−xPbI₃ perovskite.