Passivation by pyridine-induced PbI₂ in methylammonium lead iodide perovskites

Defects at discontinuities of the perovskite lattice limit the performance of the perovskite solar cell (PSC). Lead iodide (PbI₂) and pyridine have been shown to passivate these defects. We treat methylammonium lead iodide (MAPbI₃) films with pyridine solutions to investigate the effects of the two passivators. By comparing confocal fluorescence microscopy (CFM) images at 405 nm excitation and then at 559 nm excitation we demonstrate the pyridine treatment passivates and forms PbI₂ crystallites which cause additional passivation.