A facile single injection Hydrothermal method for the synthesis of thiol capped CdTe Quantum dots as light harvesters

摘要

A facile, Single Injection Hydrothermal (SIH) method has been developed to synthesize high quality 3-​Mercaptopropionic Acid (MPA) stabilized aq. CdTe QDs, entirely in ambient environment. The synthesis protocol eliminates the use of inert atm. for reducing elemental Tellurium powder to Te precursor avoiding the oxidn. of Te powder. The XRD result revealed that the synthesized QDs are in cubic zincblende type cryst. structure, without signature of Te oxidn. FTIR spectra have confirmed the attachment of short chained org. compd. MPA to the surface of QDs by covalent bond. The Quantum confinement effect was clearly evident by shift in Longitudinal Optic (LO) peak of Raman spectra and absorption peak wavelength with respect to bulk CdTe materials. The optical direct band gap energy of CdTe QDs is between 3.63 eV to 1.96 eV and QDs size below 6 nm, confirm the QDs are well under strong Quantum confinement regime. Also, photoluminescence spectra depict a stable and high luminescence emission from green to dark red color. All these results corroborate that the synthesis of CdTe QDs procedure is very advantageous and present a simple, economical and easily up scalable method for large scale prodn.