Single silica-coated CsPbBr3 perovskite quantum dots with enhanced stability and excellent optical properties

Halide perovskite quantum dots (PQDs) have been considered to be potential emitting materials for illumination and display applications. Unfortunately, the poor stability (air, water, and thermal) can greatly limit their practical applications. Herein, the mono-dispersed pure CsPbBr3 PQDs with cubic morphologies are prepared by using a modified hot-injection method, as a control group. Based on this, a new surface activation strategy for preparing single CsPbBr3@SiO2 core-shell PQDs with their initial cubic morphology and optical properties has been developed, using the CsPbBr3 PQDs as a precursor and choosing the APTES as the surface ligand which can form a Si-O-Si covalent bond with the subsequently added silane to help complete single CsPbBr3@SiO2 PQDs. The average thickness of the coated shell is about 2.3 nm and basically maintains the initial morphology and optical properties of PQDs. The PL intensity of CsPbBr3@SiO2 PQDs dispersed in a mixed solution of toluene and water can retained 35% of the initial value even after 13 h, which are much higher than the pure CsPbBr3 PQDs (9%). The photo-stability tests (air, water, and thermal stability) indicate that the CsPbBr3@SiO2 PQDs is markedly more stable than that of the CsPbBr3 PQDs owing to the complete encapsulation of the SiO2 shell, indicating that the host packaging is an effective way to improve the stability. This work provides a simple and reliable synthesis way to synthesize the single core-shell particles, which can be suitable for other perovskite systems.