Microwave synthesis of water-dispersed CdTe/CdS/ZnS core-shell-shell quantum dots with excellent photostability and biocompatibility

Microwave irradiation synthesis of water-dispersed CdTe/CdS/ZnS core-shell-shell (CSS) quantum dots (QD) with excellent photostability and biocompatibility, in the aqueous phase, was reported. The PL intensity of as-prepared QDs are found to be higher to that of corresponding CdTe/CdS QDs, as the ZnS shell effectively reduces the number of defects on the surface of the QDs. The diffraction of bare CdTe QDs is found to be similar to that of bulk cubic CdTe, while diffraction patterns of CS and CSS QDs shift to higher angles. The emergence of new Zn3p3, Zn Auger, and Zn2p peaks in the CdTe/CdS/ZnS QDs validates the proposed CSS structure in which ZnS acts as the second shell encapsulating the CdTe core QDs. The CSS QDs are found to be extremely stable and do not change their optical properties when stored in ambient conditions.