Aqueous synthesis of highly monodispersed thiol-capped CdTe quantum dots through electrochemical approach

A facile green approach has been developed to control the growth regime in the aqueous synthesis of CdTe semiconductor Quantum dots (QDs) via the electrochemistry method. The Low growth temperature and slow injection of Te precursors are used to prolong the diffusion controlled stage and thus suppress Ostwald ripening during nanocrystal growth. The experimental results showed that a low concentration of Te precursor would definitely influence the growth procedure. The narrow absorption peaks in the UV-visible absorption spectra, as well as transmission electron microscopy images indicated that the as-prepared CdTe QDs had a good monodispersity. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggested that the as-prepared QDs have high crystallinity and cubic structure. The QDs exhibited high fluorescence QYs about 50% and the best of QY 67% without any postpreparative treatment over a broad spectral range of 516-609 nm, which could be further broadened by long-term refluxing. The current work suggested that electrochemical method was an attractive approach to the synthesis of high-quality II-VI semiconductor QDs at a large scale.