Non-TOP and Non-Injection Synthesis of Zinc-Blende CdSe Using Cyclo-Hexeno-1,2,3-Selenadiazole: Quantum Dots versus Magic-Size Nanocrystals

摘要

The controlled synthesis of CdSe quantum dots via the thermolysis of a labile selenium precursor i.e., cyclo-hexeno-1,2,3-selenadiazole has been investigated at the specific Se to Cd mole ratios of 1:1 and 1:2. The experimental results reveal that the reaction of selenadiazole with cadmium acetate at 180℃ in the presence of oleic acid and diphenyl ether produces exclusively zinc-blende (cubic) crystallites of ～3 nm size. Varying the temperature, surfactants, solvent and surfactant ratio demonstrate conditions which are specific either for the formation of "quantum dots" or "magic-size" nanoclusters. The present non-injection approach where the reactivity and concentration of reactants are useful parameters for exercising control over the type of particle formed is a "green" synthesis avoiding the use of generally employed "toxic" phosphine or amine reagents and produces quantum dots of high quality. The detailed spectral characterization of quantum dots by UV-visible (UV-Vis), photoluminescence (PL), infra-red (IR) and X-ray photoelectron spectroscopy (XPS) analysis as well as by transmission electron microscopy (TEM), energy dispersive analysis of X-ray (EDAX) and X-ray diffraction (XRD) measurement is described.