Low-Temperature Aging Provides 22% Efficient Bromine-Free and Passivation Layer-Free Planar Perovskite Solar Cells

icle Highlights By low-temperature aging, superior bromine-free FA 1– x MA x PbI 3 perovskite film is realized. By suppressing lead iodide on the surface of perovskite, no further passivation step or layer is needed. The efficiency of planar perovskite solar cells is improved to 22.41% with robust reproducibility.