High-Quality Single-Mode Lasers Based on Zero-Dimensional Cesium Lead Halide Perovskites

Zero-dimensional (0D) perovskites are emerging as a class of optoelectronic materials due to their unprecedented strong excitonic properties and high stability. Although the photoluminescence properties of 0D perovskites (Cs4PbX6) are investigated, the origin of green emission is still opaque, and their lasing performances are not reported. Herein, using the femtosecond transient absorption measurements to study the photophysical properties of Cs4PbBr6, the presence of polarons in Cs4PbBr6 is revealed, which provides the evidence that the green emission is contributed from the intrinsic behavior of Cs4PbBr6 rather than CsPbBr3 impurities. The successful lasing achieved from Cs4PbBr6 microdisks (MDs) by a room-temperature reverse microemulsion method is demonstrated. The as-prepared MDs with a smooth surface and a regular geometric structure can act as ideal whispering-gallery-mode microcavities. Optically pumped single-mode lasing with a low threshold and high-quality factor is successfully achieved from MDs under both one- and two-photon excitation at room temperature. The MDs display an excellent stability while stored under ambient conditions for several months. In addition, the phase transformation between CsPbBr3 and Cs4PbBr6 can be easily achieved via tuning the amounts of surfactants. This work suggests that 0D perovskites can be promising materials toward the development of miniaturized lasers and other optoelectronic devices.