Color‐Tunable Photoluminescence and Whispering Gallery Mode Lasing of Alloyed CsPbCl 3(1– x ) Br 3 x Microstructures

Bandgap engineering of perovskite micro/nanostructures is important in designing multifunctional optoelectronic circuits. Especially, wavelength tunable lasing and modes are essential to the practical applications of micro/nanoscale lasers. Here, for the first time, a sample source-moving chemical vapor deposition approach for the spatial bandgap engineering of cesium lead halide perovskites (CsPbCl3(1–x)Br3x, X = 0–0.75) alloy microstructures on a single sapphire substrate is reported. Owing to temperature-selected effort along the deposition zoon, cesium lead halide perovskites alloy CsPbCl3(1–x)Br3x microcrystals with engineerable bandgap from 2.39 to 2.91 eV are obtained. The emission light can be modulated gradually from blue (425 nm) to green (512 nm) under a 320 nm laser illumination. Furthermore, these alloyed perovskites structures grown on the sapphire substrate show stable emission with no measurable degradation after 24 h under a continuous wavelength 320 nm laser radiation. More importantly, high-quality wavelength tunable whispering gallery mode lasing with emission peaks from 429 to 521 nm are first successfully fabricated based on these alloyed pervoskite crystals. These composition-graded perovskite microcrystals demonstrated here may find applications in multicolor display and broad band light sources.