Microemulsion-mediated synthesis of cadmium zinc sulfide nanocrystals with composition-modulated optical properties

Cadmium zinc sulfide nanocrystals were synthesized by a microemulsion-mediated process, which involving two steps: the preparation of CdS (or ZnS) seeds and the succedent hydrothermal growth of ZnS (or CdS) component. The XRD results show that the cadmium zinc sulfide nanocrystals with CdS seeds present a hexagonally homogeneous alloyed structure, while the ones with ZnS seeds mainly take on the characteristic of hexagonal CdS nanocrystals. The intrinsic factors influencing the crystal structures were discussed. The UV-vis and photoluminescence (PL) spectra indicate that the optical properties of the obtained nanocrystals with CdS seeds can be continuously modulated by tuning their compositions, although their sizes and size distributions are not under a strict control. The composition-modulated strategy, along with the hydrothermal microemulsion process, will be an effective route to achieve semiconductor nanocrystals with tunable optical properties under more manageable conditions.