Mechanochemical synthesis of stable, quantum-confined CsPbBr₃ perovskite nanocrystals with blue-green emission and high PLQY

Cesium lead halides are a family of bright, visible-light emitting materials with near-unity photoluminescence quantum yield (PLQY) in nanocrystals (NCs). The usual way to achieve visible light-emission tunability is by mixing halides, which often leads to phase separation and poor stability. While the NCs should also show size-dependent PL emission, reports on strong quantum confinement in these materials are scarce. Here, we report the synthesis of quantum-confined cesium lead bromide (CsPbBr₃) NCs via a facile, environment-friendly, and scalable high-energy mechanochemical synthesis route. The PLQY measured is similar to 85%, even after 90 days of synthesis, and the emission wavelength is shifted from green, 520 nm, to blue, 460 nm by quantum confinement in NCs of size 3-5 nm. Micro-PL optical spectroscopy and atomic force microscopy confirm the size tunability of PL on a single-dot scale. Our work demonstrates the potential of mechanochemical synthesis in the medium-scale production of bright luminescent quantum-confined NCs that could be extended to other materials as well.