(FA_0.83MA_0.17)_0.95Cs_0.05Pb(I_0.83Br_0.17)₃ Perovskite Films Prepared by Solvent Volatilization for High‐Efficiency Solar Cells

Perovskite solar cells (PSCs) have attracted significant research efforts due to their remarkable performance. However, most perovskite films are prepared by the antisolvent method which is not suitable for practical applications. Herein, a (FA_0.83MA_0.17)_0.95Cs_0.05Pb(I_0.83Br_0.17)₃ (CsFAMA) perovskite film fabrication technique is developed using solvent volatilization without any antisolvents. The films are formed through recrystallization via the intermediate phase CsMAFAPbI _x Cl _y Br _z during annealing, leading to high‐quality perovskite films. The perovskite growth mechanism is investigated in terms of controlling the amount of formamidinium iodide and methylammonium chloride in the precursor solutions. The oriental growth of the films via the intermediate phase is confirmed by the grazing‐incidence wide‐angle X‐ray scattering measurements. The photovoltaic properties of the perovskite films are investigated. The PSCs based on the films fabricated using the method exhibit a high efficiency of 20.6%. The method developed in this work is based on solvent volatilization, which exhibits significant potential in high reproducibility, facile operation, and large‐scale production.