Formation of highly uniform thinly-wrapped CsPbX3@silicone nanocrystals via self-hydrolysis: suppressed anion exchange and superior stability in polar solvents

Cesium lead halide (CsPbX3, X = Cl, Br and I) perovskite nanocrystals have been exhibiting promising potential in optical and photonic applications, whereas there are challenges in improving the stability of nanocrystals toward their surroundings, owing to their highly ionic nature and inconsistency in the crystal lattice. Wrapping particles with insulating materials has been evidenced as an effective strategy but usually at the cost of poor morphology and low ensemble uniformity. Herein, we report a facile and robust approach for synthesizing highly uniform CsPbX3 nanocrystal ensembles, in which particles remain in a conventional cubic shape and are wrapped with thin silicone layers (CsPbX3@silicone) by controlling self-hydrolysis of the precursor (3-aminopropyl)triethoxysilane (APTES). Such silicone wrapping effectively passivates the surface-defects and restrains charge carrier losses from nanocrystals, leading to an enhancement in photoluminescence quantum yields. Our CsPbX3@silicone nanocrystals show great ability to resist harsh polar environments while maintaining the cubic phase for longer than 3000 hours. We also found that such silicone wrapping effectively prevents exchange of halide anions in the multi-halide-component system. Our work paves a way for making highly uniform and environment-insulating inorganic perovskite nanocrystals, which are a promising candidate for applications in lasers, light-emitting devices and other optical devices.