Solvent coordination engineering for high-quality hybrid organic-inorganic perovskite films

Identifying the structure of iodoplumbate complexes in various solutions is essential for linking the coordination environment of the perovskite precursor to its final properties. In this study, we investigate the structure of methylammonium lead iodide (MAPbI3) perovskite precursor solutions as a function of the volume ratio of N,N-dimethylformamide and dimethyl sulfoxide (DMSO) using X-ray absorption fine structure spectroscopy. It was demonstrated that DMSO modifies the precursor structure at the atomic level. X-ray diffraction, scanning electron microscopy, and UV–Vis spectroscopy analyses showed that the coordination environment of iodoplumbate complexes in precursor solutions is strongly correlated with the morphology of perovskite films. The appropriate amount of DMSO in the precursor solution modifies the Pb-O and Pb-I coordination of iodoplumbate complexes, which could change the growth process of high-crystallization perovskite films. This study sheds light on the formation mechanism of perovskite films from precursor solutions, which will lead to the development of high-quality films and ultimately high-efficiency devices.