Ionic liquid tailoring defect/interface-induced recombination loss toward enhanced Dion–Jacobson perovskite lasing

Quasi-two-dimensional (2D) Dion–Jacobson (DJ) perovskites demonstrate remarkable photophysical properties and exhibit tremendous potential in amplified spontaneous emission (ASE) and lasing. However, their inferior crystallinity and the inappropriate multiphase structure in the quasi-2D perovskite seriously affect the energy transport efficiency in the energy funnel and the lasing threshold, which severely impedes the pace of development in this emerging area. Here, we report a green ASE with a low threshold of 8.2 μJ/cm2, accomplished by introducing an ionic liquid additive strategy that refines the crystallization kinetics, passivates defect-rich small-n (n = 1, 2) phases, and improves energy funneling in the quasi-2D (BDA)(MA)3Pb4Br13 perovskite film. The single-mode vertical-cavity laser is demonstrated with a low threshold of 9.98 μJ/cm2, a narrow linewidth of 0.47 nm, and a quality factor of 1125.3. This work will be helpful for further prompting the performances of the low-threshold lasers based on DJ perovskites.