Selective synthesis of CdTe and high luminescence CdTe/CdS quantum dots: the effect of ligands

This paper describes the selective syntheses of high luminescence CdTe and core-shell CdTe/CdS quantum dots (QDs) in aqueous solution by simple heating refluxing at 100 degrees C. CdTe QDs are prepared by using three kinds of ligands (thioglycolic acid-TGA, tiopronin-TP, and glutathione-GSH) as stabilizer, respectively. The results of refluxing for 10 min to several hours indicate that GSH-capped CdTe QDs have higher photoluminescence quantum yields (QY 54%) than TGA (QY 41%)- and TP (QY 24%)-stabilized CdTe QDs. Further, using TP-CdTe as core template and GSH as stabilizer and sulfur source, high luminescence GSH-capped CdTe/CdS core-shell QDs have been successfully synthesized in aqueous solution by simple refluxing at 100 degrees C. The GSH-CdTe/CdS QDs exhibit high fluorescence QYs about 55% over a broad spectral range of 530-588 nm, with the best QY of 83%. TP-stabilized CdTe/CdS QDs are also synthesized with TP as stabilizer and thioacetamide (TAA) as sulfur source, and with the best QY of 80%. GSH-stabilized CdTe and CdTe/CdS QDs are highly biocompatible, monodispersed, and stable under physiological conditions. The method of QDs prepared using GSH is simple and environmentally friendly, and it can be easily extended to the large-scale, aqueous-phase production of QDs.