A micro-laser grown from non-photoluminescent Cs4PbBr6 nanocrystals

The 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 owing to the large bandgap and strong ionic and covalent bonds in the crystal structure, which inhibit photon emission in the visible light spectrum. Nonetheless, its easily convertible properties compared with other 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-nanolasers and strengthens the connections among various perovskite derivatives. The nanowires exhibit excellent quantum size effects and are microdevices with polarized photoluminescence emission capability. Meanwhile, large-sized microrods exhibit perfect lasing performance with a low threshold of similar to 34 mu J cm-2 and a high Q-factor of similar to 1229. Owing to these high-quality performances, the Cs4PbBr6 nanocrystals exhibit significant potential in diverse fields such as optical communication, biomedical applications, photonics and optoelectronics.