Solution‐Grown CsPbBr3/Cs4PbBr6 Perovskite Nanocomposites: Toward Temperature‐Insensitive Optical Gain

With regards to developing miniaturized coherent light sources, the temperature‐insensitivity in gain spectrum and threshold is highly desirable. Quantum dots (QDs) are predicted to possess a temperature‐insensitive threshold by virtue of the separated electronic states; however, it is never observed in colloidal QDs due to the poor thermal stability. Besides, for the classical II–VI QDs, the gain profile generally redshifts with increasing temperature, plaguing the device chromaticity. Herein, this paper addresses the above two issues simultaneously by embedding ligands‐free CsPbBr₃ nanocrystals in a wider band gap Cs₄PbBr₆ matrix by solution‐phase synthesis. The unique electronic structures of CsPbBr₃ nanocrystals enable temperature‐insensitive gain spectrum while the lack of ligands and protection from Cs₄PbBr₆ matrix ensure the thermal stability and high temperature operation. Specifically, a color drift‐free stimulated emission irrespective of temperature change (20–150 °C) upon two‐photon pumping is presented and the characteristic temperature is determined to be as high as ≈260 K. The superior gain properties of the CsPbBr₃/Cs₄PbBr₆ perovskite nanocomposites are directly validated by a vertical cavity surface emitting laser operating at temperature as high as 100 °C. The results shed light on manipulating optical gain from the advantageous CsPbBr₃ nanocrystals and represent a significant step toward the temperature‐insensitive frequency‐upconverted lasers.