Solvent atmosphere-assisted crystallization of perovskites for room-temperature continuous-wave amplified spontaneous emission

Low-threshold, solution-processable quasi-two-dimensional (quasi-2D) perovskites hold great significance in the development of compact, solution-processable lasers. However, defects such as pinholes, caused by the rapid crystallization process and non-uniform distribution of mixed phases, contribute to increased optical losses and decreased energy transfer. In this study, we developed a simple strategy involving DMSO atmosphere-assisted crystallization for preparing quasi-2D perovskite films. This approach allows effectively controlling the surface crystallization process, resulting in a smooth surface morphology and improved phase distribution. Consequently, the non-radiative recombination rate decreases, while the fluorescence quantum yield increases. As a result, using the PEA(2)FA(n-1)Pb(n)Br(3n+1) (n = 6) film with DMSO atmosphere treatment, we achieved a low pulse optically pumped amplified spontaneous emission (ASE) threshold of 12.9 & mu;J cm(-2), which was 3.6 times lower than the case without atmosphere treatment. Furthermore, by incorporating a microcavity structure to enhance optical feedback, we successfully achieved continuous-wave (CW) optically pumped ASE at room temperature with an extremely low threshold of 3.8 W cm(-2).