Facile fabrication of large-grain CH3NH3PbI3-xBrx films for high-efficiency solar cells via CH3NH3Br-selective Ostwald ripening

Organolead halide perovskite optoelectronic devices require high material quality. Here, Yang et al. show that methylammonium lead iodide films can undergo Ostwald ripening and become mixed-halide films using methylammonium bromide treatment. This processing increases both the device efficiency and stability.