Construction of Highly Luminescent CdTe/CdS@ZnS–SiO₂ Quantum Dots as Conversion Materials toward Excellent Color-Rendering White-Light-Emitting Diodes

Highly red-luminescent N -acetyl- l -cysteine-stabilized CdTe/CdS@ZnS–SiO 2 quantum dots (QDs) were successfully synthesized in the aqueous phase via a promising microwave strategy for the first time; they were prepared by coating SiO 2 layers doped with ZnS-like clusters on CdTe/CdS core/shell QDs. Owing to the effective passivation of the coating CdS shell and ZnS–SiO 2 layer, the as-prepared QDs show high photoluminescence, good optical stability, and low biotoxicity. Moreover, the outermost SiO 2 layer endows the QDs with excellent silicone compatibility. The structures and photoluminescence properties of the CdTe/CdS@ZnS–SiO 2 QDs were well studied by various characterizations. For their practical applications, we explored the promising red-luminescent QDs as novel red phosphors to fabricate two types of white-light-emitting diodes (WLEDs), a low-power surface-mounted device and a high-power device. Both of the devices produce bright white light with remarkable color rendering. Especially, the color-rendering index (CRI) of the high-power device even reaches up to 91.9, suggesting the great potential of the highly red-luminescent QDs for solid-state lighting systems with high CRI.