Highly stable water-soluble ZnSe:Cu quantum dots coated with doubly ZnS shell

Doped ZnSe quantum dots (QDs) have become a potential substitute for Cd-based QDs. In this paper, center-doped monodisperse Cu-doped ZnSe (ZnSe:Cu) QDs are synthesized as the first step in aqueous solution by co-nucleation doping method, and then the double-layered ZnS shell is grown by successive growth. The prepared ZnSe:Cu/ZnS/ZnS QDs have high photoluminescence(PL) intensity and excellent stability in the blue region. The crystal structure has not been changed and the PL intensity maintains 95% after 365 days stored in the air. The outstanding performance of the prepared QDs benefit from the ZnS shell grown outside the core of ZnSe:Cu, especially the second layer of the ZnS shell can effectively limit excitons and Cu in the ZnSe core and isolate O₂. The strategy in our work paves a new path to elevate the stability of QDs.