Surface ligand modified cesium lead bromide/silica sphere composites for low-threshold upconversion lasing

Abstract

In recent years, all-inorganic halide perovskite quantum dots (QDs) have drawn attention as promising candidates for photodetectors, light-emitting diodes, and lasing applications. However, the sensitivity and instability of perovskite to moisture and heat seriously restrict their practical application to optoelectronic devices. Recently, a facile ligand-engineering strategy to suppress aggregation by replacing traditional long ligands oleylamine (OAm) during the hot injection process has been reported. Here, we further explore its thermal stability and the evolution of photoluminescence quantum yield (PLQY) under ambient environment. The modified CsPbBr 3 QDs film can maintain 33% of initial PL intensity, but only 17% is retained in the case of unmodified QDs after 10 h continuous heating. Further, the obtained QDs with higher initial PLQY (91.8%) can maintain PLQY to 39.9% after being continuously exposed in air for 100 days, while the PLQY of original QDs is reduced to 5.5%. Furthermore, after adhering CsPbBr 3 QDs on the surface of a micro SiO 2 sphere, we successfully achieve the highly-efficient upconversion random laser. In comparison with the unmodified CsPbBr 3 QDs, the laser from the modified CsPbBr 3 QDs presents a decreased threshold of 79.81    μJ / cm 2 and higher quality factor ( Q ) of 1312. This work may not only provide a facile strategy to synthesize CsPbBr 3 QDs with excellent photochemical properties but also a bright prospect for high-performance random lasers.