Aqueous synthesis of thiol-capped CdTe quantum dots and its photoluminescence enhancement via room temperature treatment with alkyl chain diamines

In this study the CdTe quantum dots (QDs) are synthesized in aqueous solution with three thiol-contained capping ligands of thioglycollic acid (TGA), 3-mercaptopropionic acid (MPA), and l-cysteine (lCys). The photoluminescence (PL) enhancement of the as-prepared QDs is also conducted via room temperature treatment with alkyl chain diamines. Our measurements on the ultraviolet-visible (UV-vis) absorption and fluorescence emission reveal that both the growth kinetics and the PL efficiency of the QDs vary a lot with the molecular structures of the three involved ligands. In comparison with TGA and lCys, MPA endows the QDs with a wide color tuning range from cyan to deep red and strong PL emission while its full width at half maximum (FWHM) is regretfully large. Notable enhancement on PL emission is achieved for the TGA and MPA capped QDs via room temperature treatment with diamines solutions while in the case of the QDs capped by lCys the enhancement is practically meaningless.