Sellotape Exfoliated Layered Quasi‐2D Perovskite Thin Film for Efficient Light‐Emitting Diodes

Abstract In 2004, K. S. Novoselov and A. K. Geim et al. have used sellotape to peel off the layered 2D graphite, and successfully obtained few‐layer thin graphene. Inspired by this, herein, the sellotape is initially used to exfoliate the layered Ruddlesden–Popper (RP) quasi‐2D perovskite film for efficient light‐emitting diodes application. The top surface layer of quasi‐2D perovskite film is mechanically peeled off by the sellotape without damaging the crystalline region below, which minimizes the poor conductivity issue of quasi‐2D perovskite film owing to the decreased defect density. Moreover, the exfoliated quasi‐2D film exhibits low charge traps density and enhanced energy transfer from low‐dimensional to high‐dimensional domains due to the elimination of surface defective layer and the recrystallization of quasi‐2D perovskite crystal, leading to high photoluminescence quantum yield (PLQY) up to 83.2%. Subsequently, an efficient perovskite light‐emitting diode based on the exfoliated quasi‐2D perovskite thin film is achieved with high current efficiency of 46.0 cd m −2 and excellent external quantum efficiency (EQE) up to 14.8%.