The Effect of Decomposed PbI2 on Microscopic Mechanisms of Scattering in CH3NH3PbI3 Films

Hybrid organic-inorganic perovskites (HOIPs) exhibit long electronic carrier diffusion length, high optical absorption coefficient, and impressive photovoltaic device performance. At the core of any optoelectronic device lie the charge transport properties, especially the microscopic mechanism of scattering, which must efficiently affect the device function. In this work, CH₃NH₃PbI₃ (MAPbI₃) films were fabricated by a vapor solution reaction method. Temperature-dependent Hall measurements were introduced to investigate the scattering mechanism in MAPbI₃ films. Two kinds of temperature-mobility behaviors were identified in different thermal treatment MAPbI₃ films, indicating different scattering mechanisms during the charge transport process in films. We found that the scattering mechanisms in MAPbI₃ films were mainly influenced by the decomposed PbI₂ components, which could be easily generated at the perovskite grain boundaries (GBs) by releasing the organic species after annealing at a proper temperature. The passivation effects of PbI₂ in MAPbI₃ films were investigated and further discussed with emphasis on the scattering mechanism in the charge transport process.