Edge States in 2D A₂PbBr₄ Hybrid Perovskites Enabled by Local Structural Reorganization

The edge states (ES) in two-dimensional (2D) hybrid lead halide perovskites (LHPs) exhibit distinct electronic characteristics, including lower energy and longer lifetimes compared to the interior states (IS). Though the ES of these 2D LHPs show prospect of facilitating photovoltaic and optoelectronic effects, the underlying mechanism remains elusive. Here, the occurrence of ES in a family of 2D A₂PbBr₄ (A = organic amine cation) LHPs is attributed to the Rashba/Dresselhaus (RD) spin splitting induced 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. This 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.