Direct imaging of carrier diffusion length in organic-inorganic perovskites

Abstract

The carrier diffusion length (LD) is of great relevance to the quantum efficiencies of organic-inorganic perovskites. However, so far there is no direct and noncontact measurement of the carrier diffusion length in this emerging material. Herein, we directly visualize the carrier diffusion length of organic-inorganic perovskites via spatial mapping of photoluminescence. Our results reveal that the carrier diffusion length (LD) is 6.25 μm for three-dimensional FAPbBr3 single crystals. Further, we discover that nonlinear and nonradiative effects can be neglectable during the diffusion process of photogenerated carriers in FAPbBr3 single crystals. In contrast, two-dimensional BA2PbI4 single crystals display shorter LD (2.40 μm) due to the transport barrier from their insulating organic layer. Our work simplifies the complicated operation for carrier diffusion length measurements, which is fundamentally important for technical development and scientific research on organic-inorganic perovskites.