Synthesis of highly luminescent CdTe/CdS/ZnS quantum dots by a one-pot capping method

摘要

In the present article, a one-pot capping method with very simple procedure was developed to synthesize highly luminescent CdTe/CdS/ZnS quantum dots (QDs). CdTe aqueous solution was introduced into a precursor solution containing Cd~(2+), Zn~(2+) and mercaptopropionic acid (MPA), and sulfur solution was then added for capping a CdS/ZnS shell on CdTe core. Synthesis conditions such as refluxing time, dropping rate of Na2S and molar ratio of Cd~(2+):Zn~(2+):S~(2-):MPA were investigated. The optical properties of the as-prepared QDs in absoption and photoluminescence were studied. The experimental results revealed that the CdTe/CdS/ZnS QDs prepared by the one-pot capping method had photoluminescent quantum yield up to 73%, broad excitation spectrum of 100 nm, good pH tolerance and photostability. Transmission electron microscopy showed that the CdTe/CdS/ZnS QDs were nearly spherical and monodispersed with the average size of about 10 nm. X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy confirmed the core/shell/shell structure of CdTe/CdS/ZnS. XRD demonstrated that the CdTe/CdS/ZnS QDs possessed ideal crystal structure.