Abstract
Metal halide perovskite thin films have achieved remarkable performance in optoelectronic devices. To achieve higher device performance and reliability needed for wide-spread commercial deployment, spatial heterogeneity of optoelectronic properties in the perovskite thin films needs to be understood and controlled. However, clear identification of the causes underlying the heterogeneity has remained elusive. Here, we employ a multimodal imaging approach to separate electronic heterogeneity from morphology variations in perovskite thin films. Our results reveal that disorders in the crystallographic orientation of grains and different surface terminations are the primary cause of the electronic heterogeneity. Therefore, a solution processed polycrystalline perovskite thin film with a negligible spatial variation in charge trap site density reaching that of single crystals can be achieved by minimizing crystallographic orientation disorder.
