This work presents a visual growth strategy based on water-induced phase transitions, which enables real-time tracking and structural regulation of Cs 4 PbBr 6 -to-CsPbBr 3 microcrystal transformation under ambient conditions without the need for high-energy beams or vacuum. Driven by the difference in the dissolution rates of CsBr and PbBr 2 in water, the slow progression of the reaction interface allows clear observation of crystal morphology evolution under a conventional fluorescence microscope. The microcrystals obtained through strategy possess highly regular structural morphology and superior optical properties. In the experiments, micron-scale-wire exhibiting size-dependent polarized emission and bulk-microcrystals supporting multimode lasing emission were successfully constructed. Further analysis revealed the significant influence of crystal size on excited-state dynamics, cavity mode selectivity, and emission characteristics, thereby establishing a direct link between structural visual regulation and functional photon output. This work delivers mechanistic insights and experimental evidence for controllable fabrication of low-threshold lasers and polarized light-emitting devices.
Self-powered photodetectors (SPPDs) have attracted lots of attention due to their various advantages including no external power sources, high-sensitivity, fast response speed, and so on. This study reports the fabrication and characterization results of CsPbBr3 microcrystals (MCs) grown by chemical vapor deposition (CVD) method, and the SPPDs have been fabricated on the basis of the CsPbBr3 MCs layer with the sandwich structure of GaN/CsPbBr3 MCs/ZnO. Such designed SPPD shows the detectivity (D*) of 1014 Jones, on/off ratio of up to 105, peak responsivity (R) of 89.5 mA/W, and enhanced stability at the incident wavelength of 540 nm. The photodetector enables the fast photoresponse speed of 100 μs rise time and 140 μs decay time. The performances of the SPPD are comparable to the best ones ever reported for CsPbBr3 based PDs but do not need external power supplies, which mainly benefit from the low trap density, long carrier diffusion of high quality CsPbBr3MCs film, and the built-in electric fields in the sandwich structure of GaN/CsPbBr3/ZnO layers.
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