Cyclodextrin-Modified CsPbBr ₃ Quantum Dots for Room-Temperature Single-Mode Vertical-Cavity Surface-Emitting Lasers

Perovskite quantum dots (PQDs) have garnered significant attention as promising gain media for laser applications due to their excellent optical properties. However, the dynamic binding behavior of conventional long-chain insulating ligands (oleic acid/oleylamine, OA/OAm) to QD surfaces inherently generates unfavorable defect states, exacerbating nonradiative recombination and fundamentally limiting their optoelectronic performance. In this work, we report a facile room-temperature synthetic strategy for high-performance CsPbBr3 PQDs by utilizing β-cyclodextrin (β-CD) instead of a mixed OA/OAm solution as a ligand. The β-CD-encapsulated CsPbBr3 PQDs present a maximum of 556% enhancement in photoluminescence (PL) intensity under an ambient environment compared to the OA/OAm-ligand counterparts. The pump power-dependent PL measurements reveal a 38% higher internal quantum efficiency, and further analysis based on a Bose–Einstein statistical model indicates a reduced defect density and superior excitonic recombination in such β-CD-modified PQDs. Additionally, by employing the PQDs as a gain medium, we successfully demonstrate a room-temperature single-mode surface-emitting laser with stable outputs and a low lasing threshold. This work not only presents a significant step forward in PQD synthesis and surface ligand engineering but also provides guidance for developing high-performance optoelectronic devices.