Hydrothermal Synthesis of High-Quality Thiol-Stabilized CdTexSe1-x Alloyed Quantum Dots

Abstract

Alloyed semiconductor quantum dots (QDs) enriched the synthetic routes for engineering materials with unique structural and optical properties. High-quality thiol-stabilized CdTe(x)Se(1-x) alloyed QDs were synthesized through a facile and economic hydrothermal method at 120 °C, a relatively low temperature. These water-soluble QDs were prepared using different capping agents including 3-mercaptopropionic acid (MPA) and L-cysteine (L-Cys). The photoluminescence (PL) intensity and stability of L-Cys-capped CdTe(x)Se(1-x) QDs were found to be higher than that of MPA-stabilized ones. The molar ratios of Se-to-Te upon preparation were adjusted for investigating the effect of composition on the properties of the resulting QDs. We also investigated the effect of the pH value of the reaction solution on the growth kinetics of the alloyed CdTe(x)Se(1-x) QDs. The resulting CdTe(x)Se(1-x) QDs were characterized by UV-vis absorbance and PL spectroscopy, powder X-ray diffraction, and transmission electron microscopy. Being coated with a CdS inorganic shell, the PL intensity and stability of the CdTe(x)Se(1-x)/CdS core-shell QDs were drastically enhanced, accompanied by the red-shift of the PL peak wavelength. Owing to the unique optical properties, the QDs hold great potential for application and have to be further exploited.