Compact-Type Quasi-2D Perovskites MAPbBr₃@FABr: Reduced Interlayer Distances Enable Ultralow Threshold Lasing and...

Quasi-2D perovskites have garnered significant attention as promising materials for laser applications due to their superior optical gain and environmental stability. However, the thick insulating spacer layers between semiconducting perovskite slabs impede efficient charge transport, constraining their overall performance. Herein, we introduce a new family of compact-type quasi-2D perovskites with substantially reduced interlayer spacing. This design promotes rapid energy funneling, yielding an amplified spontaneous emission (ASE) threshold of 1.82 µJ cm^-2, the lowest reported for green-emitting quasi-2D perovskites, and an optical gain coefficient of 413.77 cm^-1. Furthermore, the short interlayer distance, coupled with precisely aligned semiconducting layers, yields electron mobilities exceeding those of traditional counterparts by more than one order of magnitude. By varying the halogen composition from bromine to chlorine, we produced mixed-halide variants with tunable, low-threshold ASE across a broad spectral range. We also fabricated high-quality MAPbBr₃@FABr micro-ring laser arrays, exhibiting whispering-gallery-mode lasing with a quality factor of ∼1802, thresholds of ∼1.89 µJ cm^-2 and good operational stability. This work advances the design of quasi-2D perovskites, providing a pathway for development of practical perovskite lasers with enhanced performance and broader applications.