Air-stable and low threshold amplified spontaneous emission via CsBr aqueous solution processed all-inorganic CsPbBr₃ perovskite films

Inorganic cesium lead halide perovskite (CsPbX₃, X = Cl, Br, and I) has attracted increasing attention in the field of laser application due to its excellent stability compared to the organic-inorganic hybrid perovskite since affording the radiation of a long pulse pump source requires high thermal stability of the material. However, it is difficult to observe the amplified spontaneous emission (ASE) of CsPbBr₃ using a one-step solution method due to the low solubility of CsBr in the organic solvent. Herein, we fabricate a CsPbBr₃ film with a two-step solution method and realize the ASE under the long pulse pumping. Meanwhile, a CsBr aqueous solution is used as an effective additive to increase the concentration of Cs⁺ in the precursor solution and then to improve the optical amplification properties of the CsPbBr₃ films. The films exhibit better crystalline and enhanced photoluminescence intensity. Both the ASE threshold and gain have been significantly improved. Furthermore, the optimized film shows a satisfying stability of ASE after being placed in the air for more than two months.