Edge states in 2D A2BX4 lead halide perovskites enabled by local structural reorganization

Abstract

Abstract The edge states (ES) inherent in 2D hybrid lead halide perovskites (LHPs) play host to free carriers of low energy and extended lifetimes which is distinct from the tightly bound excitons found in the interior states (IS). Though the ES of these 2D LHPs show prospect of facilitating photovoltaic effects, the underlying mechanism remains elusive. Here, we reveal the occurrence of ES in a family of 2D A2PbBr4 (A = organic amine cation) LHPs is attributed to the Rashba/Dresselhaus (RD) spin splitting caused by local structural reorganization on the crystal edge. The experimental and theoretical characterizations reveal that the local structure on the crystal edge is significantly strained, which leads to considerable out-of-plane distortion of adjacent PbBr6 octahedra, local loss of inversion symmetry and therefore spin-splitting energy required for the formation of ES. Our findings contribute fresh perspectives to the fundamental comprehension of the RD effect, extending the boundaries of spintronics and opening promising pathways for the conceptualization and refinement of devices centered on ES.