Mixed Halide Perovskite Films by Vapor Anion Exchange for Spectrally Stable Blue Stimulated Emission.

Abstract

Solution-processed all-inorganic CsPbX3 perovskites exhibit outstanding optoelectronic properties and are being considered as a promising optical gain medium, with impressive performance in the green and red region. However, the development of CsPbX3 for blue emission is still lagging far behind, owing to difficulties in thin films synthesis and spectral instability subject to light irradiation. Here, a facile vapor anion exchange (VAE) method that enables preparation of blue-emitting perovskite films with both excellent surface morphology and good photo-stability is reported. The mixed-Br/Cl quasi-2D perovskite films show spectrally stable pure blue emission (471nm) under continuous-wave laser irradiation with power density as high as 81Wcm-2 . Furthermore, optically pumped blue amplified spontaneous emission (ASE) is realized based on the mixed-Br/Cl perovskite films. By changing the duration of VAE treatment, the ASE peak can be tuned from 537nm down to 475nm. This work not only presents a facile method to prepare high quality mixed halide Cs-based perovskite films, but also pave the way for further exploration of stable blue perovskite lasing.