Room-Temperature Defect Engineering in Cl ^– -Doped CsMnBr ₃ Nanocrystals Achieves Optimized Luminescence and High Quantum Yield

Perovskite nanocrystals have gained considerable attention owing to their outstanding photoluminescence and photodetection performance in various applications. However, the rigorous preparation conditions and lead toxicity of most lead halide perovskite nanocrystals still hamper practical application, which achieves efficient deep-red and near-infrared (NIR) emission also meeting the challenge. Herein, sub-25 nm Cl–-doped lead-free CsMnBr3 nanocrystals (NCs) were prepared via a moderate hot-injection method at room temperature and the resulting NCs showcased excellent photoluminescence property with reduced impurities. Furthermore, a substantial enhancement in photoluminescence quantum yield (PLQY) from 54.20% to 78.05% was achieved by manipulating the Cl– doping concentration, which is attributed to the weakened nonradiative recombination pathways induced by Cl–-mediated defect passivation. Consequently, we fabricated photoluminescent light-emitting diodes (LEDs) based on Cl–-doped CsMnBr3 nanocrystals and achieved NIR emissions of Nd3+, Yb3+, and Er3+ ions. These results reveal that Cl–-doped CsMnBr3 perovskites NCs can not only be facilely prepared via a simple room-temperature synthesis, but also demonstrate promising potential in various areas such as photoluminescent LEDs and near-infrared optoelectronic devices.