Synthesis and characterisation of CdSe nanocrystals using NaHSeO3 as selenium source

Abstract

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 ∼4-5nm. 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 ∼125-44nm, 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. © 2012 The Institution of Engineering and Technology.