Exciton Relaxation Dynamics in Perovskite Cs₄PbBr₆ Nanocrystals

Abstract

Lower-dimensional\nmetal halide perovskites have been recognized\nas an efficient white light emitter. The broad band emission spectrum\noriginates from the recombination of excited charge carriers through\nfree excitons (FEs), self-trapped excitons (STEs), and defect-trapped\nexcitons. However, the emission properties of zero-dimensional (0-D)\nperovskites have not been explored extensively. Here, in this work,\nwe have performed low-temperature absorbance, photoluminescence (PL),\nPL excitation (PLE), PL lifetime, and Raman measurements to understand\nthe exciton relaxation processes in Cs₄PbBr₆ NCs. Our experimental observations indicate that two distinct UV\nlight spectra evolved from the photoexcited carrier recombination\nthrough FE and STE states. We emphasize that such UV light sources\ncan be beneficial for various applications, like curing of materials,\ndisinfection of viruses, hygiene control, etc.