All-inorganic halide perovskites quantum dots (QDs) have drawn a burst of 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 on optoelectronic devices.

Recently, a research team from the State Key Laboratory of High-Field Laser Physics, Shanghai Institute of Optics and Fine Mechanics (SIOM) of the Chinese Academy of Sciences (CAS) reported a facile ligand-engineering strategy to promote properties of CsPbBr₃ QDs with excellent lasting performance. Their work was published in Photonics Research on February 9, 2022.

In their experiment, the researchers synthesized CsPbBr₃-OLA QDs demonstrating better thermal stability that the modified QDs film can maintain 33% of initial PL intensity. Still, only 17% is retained in the case of unmodified QDs after 10 hours of continuous heating at 60 °C. The obtained QDs with higher initial PLQY (91.8%) can maintain PLQY to 39.9% after being continuously exposed to air for 100 days, while original QDs are reduced to 5.5%.

In addition, CsPbBr₃ QDs were coated on the surface of the micro SiO₂ to form composites. After pumping by an 800 nm femtosecond laser, we finally successfully achieved the high-efficient up-conversion random laser. Compared with the unmodified CsPbBr₃ QDs, the laser from the modified CsPbBr₃ QDs presents a decreased threshold of 79.81 μJ/cm² and a higher quality factor (Q) with 1312.

This research might provide a simple yet effective method to improve the properties of CsPbBr₃ QDs and a good prospect for the practical application of micro-nano semiconductor lasers.

Fig.1. (a) the passivation and ligand modification procedure on the surface of the CsPbBr₃ QDs. (b) Power-dependent emission spectra from CsPbBr₃-OLA/SiO₂ composite film. (c) The Gauss fitting of a select lasing peak corresponding to the Q value from CsPbBr₃-OLA/SiO₂. (Image by SIOM)