Synthesis and characterisation of CdSe nanocrystals using NaHSeO3 as selenium source

Sodium hydrogen selenite was used as a novel selenium source in the synthesis of 3-mercaptopropionic acid-stabilised cadmium selenide (CdSe) nanocrystals (NCs) in an aqueous medium. The size, crystalline structure and optical properties of these NCs were characterised via high-resolution transmission electron microscopy, X-ray powder diffraction (XRD), ultraviolet-visible light absorption and photoluminescence (PL) spectroscopy. The factors affecting the Se:Cd molar ratio were also discussed. The CdSe NC grains are roughly spherical, and their average size is ~4-5-nm. The XRD patterns of the synthesised CdSe NCs are characteristic of zinc-blended structures. The obtained CdSe NCs exhibit a relatively narrow PL band at a full-width at half-maximum of ~125-44-nm, as well as a high PL peak in the yellow spectral range. The quantum yields of the corresponding CdSe NCs at Cd-to-Se molar ratios of 0.1, 0.2 and 0.3 are 2.38, 3.70 and 9.32%, respectively, indicating the strong dependence of the NC size on the precursor concentration in the period immediately following the precursor injection.