A micro-laser grown from non-photoluminescence Cs4PbBr6 nanocrystals

All-inorganic cesium lead bromide zero-dimensional perovskite Cs4PbBr6 is highly valued for its excellent photoelectric conversion efficiency and exceptional stability. However, its application value in the visible light optical field is limited due to large bandgap and strong ionic and covalent bonds in the crystal structure, which inhibit photon emission in the visible light spectrum. Nonetheless the easily convertible properties among perovskite derivatives bring new opportunities. This study is the first to report the transformation of Cs4PbBr6 nanocrystals into CsPbBr3 nanocrystals, which then grow into nanowires and eventually form micrometer-scale optical microcavities. This innovative approach provides a novel strategy for the fabrication of perovskite micro-nano lasers and strengthens the connections among various perovskite derivatives. The nanowires exhibit excellent quantum size effects and are microdevices with polarized photoluminescence emission capability. Meanwhile, the large-sized microrods exhibit perfect lasing performance with low threshold ~34 μJ cm-2 and high Q-factor ~1229. These high-quality performances make Cs4PbBr6 nanocrystals have significant potential in diverse fields such as optical communication, biomedical applications, photonics and optoelectronics.