Ultrasonication-Assisted Ambient-Air Synthesis of Monodispersed Blue-Emitting CsPbBr₃ Quantum Dots for White Light Emission

Colloidal all-inorganic perovskite CsPbBr3 nanocrystals present versatile outstanding optoelectronic properties as well as greatly improved stability when compared with their hybrid analogues. However, the performance of blue-emitting CsPbBr3 nanocrystals is still inferior to their green counterpart. Moreover, their synthesis generally demands a high temperature and inert gas environment. Synthesis of perovskite nanocrystals with high efficiency blue emission in air ambience is highly desired. In this work we demonstrate a top-down strategy for the facile synthesis of blue-emitting CsPbBr3 quantum dots (QDs) in ambient air through cutting CsPbBr3 nanoplatelets (NPLs) into spherical QDs with the assistance of ultrasonication and hydrobromic acid (HBr) treatment. The CsPbBr3 QDs show excellent monodispersion with an average size of about 5 nm and a blue emission at 460 nm with high photoluminescence quantum yield (PL QY) of 53.2%. The key role of HBr is suggested to solubilize the inorganic cores of the NPLs and repair the surface. The CsPbBr3 QDs are used to prepare mixed phosphors emitting high quality white light.