Aqueous synthesis of highly monodispersed thiol-capped CdSe quantum dots based on the electrochemical method

A facile green approach is developed to control the growth regime in the aqueous synthesis of CdSe semiconductor quantum dots (QDs) based on the electrochemistry method. The low growth temperature and slow injection of Se precursors are used to prolong the diffusion controlled stage and thus suppress the Ostwald ripening during nanocrystal growth. The experimental results show that a low concentration of Se precursor would definitely influence the growth procedure. The narrow absorption peaks in the UV–visible absorption spectra, as well as transmission electron microscopy images indicate that the as-prepared CdSe QDs have a good monodispersity. The high-resolution transmission electron microscopy (HRTEM) images and powder X-ray diffraction (XRD) pattern suggest that the as-prepared QDs have high crystallinity and cubic structure. The QDs exhibit high fluorescence QYs of about 30% without any postpreparative treatment over a broad spectral range of 560–660 nm, which could be further broadened by long-term refluxing. The current work suggests that the electrochemical method is an attractive approach to the synthesis of high-quality II–VI semiconductor QDs at a large scale.