Laser‐induced Modifiable Dual‐wavelength Emissions from Lead Halide Perovskite Alloy Microcrystal

Abstract Due to the tunable bandgaps, high quantum efficiency, and long carrier diffusion length, perovskites have attracted significant attention as active materials for solar cells, nanoscale lasers, photodetectors, and light‐emitting diodes. Herein, laser‐induced dual‐wavelength emissions from the CsPbBr_3xI_3(1–x) perovskite alloy microcrystals are reported. Under a 375 nm laser illumination, the micro‐photoluminescence (PL) emission spectra of these microcrystals exhibit two emission bands at 570 and 690 nm with gradually increased and decreased PL intensity, respectively. Moreover, the time‐dependent emission wavelength of the two emission bands almost has no changes, while the PL intensity of both emission bands shows periodic fluctuations with the on–off switching of excitation light. This dual‐wavelength emission phenomenon suggests that phase segregation occurs in these perovskite microcrystals during laser illumination. These results would provide valuable design guidelines for perovskites‐based tunable nanophotonic devices and multi‐color displays.