A novel approach to coat silica on quantum dots: Forcing decomposition of tetraethyl orthosilicate in toluene at high temperature

The coating of silica (SiO2) on quantum dots (QDs) has been widely studied, because SiO2 can protect QDs from the damages of moisture, radiation, and heat. Conventional SiO2 coating methods for QDs are usually performed in aqueous or emulsion solutions, which require the addition of water for the hydrolysis of SiO2 precursors and lead to the photoluminescence (PL) quenching of QDs. To address this issue, a novel SiO2 coating approach on single particle level was developed by the thermally forcing decomposition of tetraethyl orthosilicate in toluene. The CdSe/CdS/ZnS:[email protected]2 nanoparticles (NPs) were prepared without decreasing the original PL quantum yield (QY), which exhibited much better photo and thermal stability in comparison with uncoated CdSe/CdS/ZnS:Al QDs. Furthermore, due to the natural formation of silanol groups on the SiO2 shell, CdSe/CdS/ZnS:[email protected]2 NPs present not only good solubility but also excellent room temperature stability in phosphate buffer saline solution for several months.