Light-Soaking Induced Optical Tuning in Rare Earth-Doped All-Inorganic Perovskite

Understanding and manipulating the photoluminescence (PL) of all-inorganic perovskites is significant in applications toward light-emitting diodes. Doping has proved to be a very promising approach for tuning the luminescence properties of perovskites. Herein, rare earth (Er and Yb) doped 3D all-inorganic perovskite flakes (CsPb(Cl/Br) 3 ) are synthesized. At room temperature, they possess a narrow emission peak at 506 nm with 10 nm linewidth and a quite broad peak at 700 nm with 170 nm linewidth, which are from band-edge PL of α-CsPb(Cl/Br) 3 and self-trapped excitons of δ-CsPb(Cl/Br) 3 , respectively. When exposing the flakes under a light-soaking, the samples present a color tuning capability spanning from red to green by extension of the soaking time, and the emission properties can recover by removing the light-soaking and undergoing a certain recovery time. Time-resolved photoluminescence indicates a photoinduced reduction of defects density in the doped perovskite flakes. Based on further density functional theory calculations, a photoinduced O 2 -diffused defect-passivation mechanism is proposed. The discovery is expected to promote the optical tuning capability of the all-inorganic perovskites and expand their potential application in optoelectronics devices.