Low-threshold amplified spontaneous emission and lasing from colloidal nanocrystals of caesium lead halide perovskites

TLDR

Metal halide perovskites are promising optoelectronic materials, yet the photophysics of uniform, size‑tunable nanocrystals remain largely unexplored. The study reports low‑threshold amplified spontaneous emission and lasing from ~10 nm monodisperse CsPbX3 nanocrystals. Room‑temperature optical amplification across 440–700 nm was achieved with thresholds as low as 5 ± 1 µJ cm⁻² and modal net gains ≥ 450 ± 30 cm⁻¹, demonstrating whispering‑gallery‑mode and random lasing in CsPbX3 nanocrystal films and microsphere resonators.

Abstract

Metal halide semiconductors with perovskite crystal structures have recently emerged as highly promising optoelectronic materials. Despite the recent surge of reports on microcrystalline, thin-film and bulk single-crystalline metal halides, very little is known about the photophysics of metal halides in the form of uniform, size-tunable nanocrystals. Here we report low-threshold amplified spontaneous emission and lasing from ∼10 nm monodisperse colloidal nanocrystals of caesium lead halide perovskites CsPbX3 (X=Cl, Br or I, or mixed Cl/Br and Br/I systems). We find that room-temperature optical amplification can be obtained in the entire visible spectral range (440-700 nm) with low pump thresholds down to 5±1 μJ cm(-2) and high values of modal net gain of at least 450±30 cm(-1). Two kinds of lasing modes are successfully observed: whispering-gallery-mode lasing using silica microspheres as high-finesse resonators, conformally coated with CsPbX3 nanocrystals and random lasing in films of CsPbX3 nanocrystals.