Depositing a ZnxCd1−xS Shell around CdSe Core Nanocrystals via a Noninjection Approach in Aqueous Media

Abstract

A ZnxCd1−xS shell was deposited around CdSe nanocrystal cores via a noninjection approach in aqueous media. The deposition of the ZnxCd1−xS shell around CdSe cores was carried out at 90 °C in a reaction flask consisting of the shell precursor compounds, together with CdSe nanocrystal cores and the capping reagent glutathione. This newly developed depositing approach uses CdCl2, Zn(OAc)2, and thiourea as Cd, Zn, and S sources, respectively. All of these chemicals were loaded at room temperature. The optical features and structure of the obtained CdSe/ZnxCd1−xS core/shell nanocrystals were characterized by UV−visible and photoluminescence spectroscopy, transmission electron microscopy, X-ray diffraction, and inductively coupled plasma atomic emission spectroscopy. The influences of various experimental variables, including the Cd-to-Zn ratio, amounts of ligand and thiourea, as well as pH value, on the growth rate and luminescent properties of the obtained core/shell nanocrystals have been systematically investigated. Through the optimization of experimental variables, the obtained water-soluble core/shell nanocrystals possess a maximum emission efficiency of 35% and a spectral width of less than 30 nm.