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

Abstract

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.