Perovskite materials have excellent optical properties, such as large carrier mobility, long diffusion length, large absorption coefficient and high quantum efficiency, which not only have excellent performance in the field of photovoltaics, but also in the fields of micro-nano lasers and light-emitting diodes. Compared with traditional three-dimensional lead-halide perovskite ABX₃, the zero-dimensional structure of perovskite has a larger exciton binding energy, higher quantum yield, unique and excellent optical properties. However, its luminescence mechanism remains controversial.

Recently, a research group from Shanghai Institute of Optics and Fine Mechanics of the Chinese Academy of Sciences, in cooperation with Chongqing University, has made a new progress in ultrafast carrier dynamics and the nano-laser performance of zero-dimensional perovskite Cs₄PbBr₆. Related research result was published in the Solar RRL as the back cover article.

In this work, researchers used femtosecond transient absorption measurements to study the photophysical properties of zero-dimensional perovskite Cs₄PbBr₆, revealing the presence of polarons in Cs₄PbBr₆, which provided that green fluorescence was contributed from the intrinsic behavior of Cs₄PbBr₆ rather than CsPbBr₃ impurities.

In addition, researchers prepared Cs₄PbBr₆ perovskite microdisks with excellent stability by a room-temperature reverse microemulsion method, and successfully realized an optically pumped single-mode laser with low threshold and high-quality factor under both one- and two-photon excitation at room temperature.

Furthermore, the phase transition between CsPbBr₃ and Cs₄PbBr₆ could be easily achieved by adjusting the amount of the surfactant. All these results indicated that zero-dimensional perovskite can be promising materials toward the development of nano-lasers.

The work was supported by the Strategic Priority Research Program of CAS, International S&T Cooperation Program of China, the National Natural Science Foundation, and the Open Fund of the State Key Laboratory of High Field Laser Physics (SIOM).

Cover article for Solar RRL 2019, Volume 4, Issue 10 (Image by SIOM)