Tunable Br-doping CH3NH3PbI3−xBrx thin films for efficient planar perovskite solar cells

The Br contents in CH3NH3PbI3−xBrx thin films linearly increased with the increase of Br contents in the methylammonium halide mixture solutions. The planar CH3NH3PbI3−xBrx solar cell using the methylammonium halide mixture solutions with the molar ratio of CH3NH3Br/CH3NH3I = 10/90 achieved a best photoelectric conversion efficiency (PCE) of 14.88% and an average PCE of 14.21 ± 0.67%.75