Zinc selenide (ZnSe) nanocrystals were synthesized via a phosphine-free route using the highly reactive alkylamine-H 2 Se complex as selenium precursor and zinc precursors with different reactivity. The reactivity of zinc precursor was tuned by using three kinds of zinc carboxylates with different alkyl chain lengths, including zinc acetate, zinc nonanoate, and zinc stearate. The effect of the reactivity and the amount of zinc precursor on nucleation and growth of ZnSe nanocrystals were investigated by ultraviolet-visible absorption and photoluminescence spectra. Result indicates that the growth and optical property of the resulting ZnSe nanocrystals are strongly dependent on the alkyl chain length and the amount of the zinc carboxylates and both shorter alkyl chain length, and more amount of zinc carboxylate will lead to faster growth of ZnSe nanocrystals. This allows that the controlled growth and excellent optical property of high-quality ZnSe nanocrystals can be achieved by combining the different reactivity and the used amount of zinc precursor, such as by using stoichiometric and reactive Zn precursor and Se precursor or by using larger amount of more unreactive Zn precursor relative to the highly reactive alkylamine-H 2 Se complex precursor.
Lai-Jun Zhang,Xing-Can Shen,Hong Liang,Jia-Ting Yao
Four families of magic-sized ZnSe quantum dots (ZnSe MSQDs) with the first exciton absorption peaks at 280 nm (F280), 291 nm (F291), about 319 nm (F319), and 347 nm (F347) were synthesized using fatty amine−H2Se complex as selenium precursor via noninjection one-pot or hot-injection approaches. The formation, growth, and transformation of these families of ZnSe MSQDs were monitored mainly by ultraviolet−visible absorption spectroscopy. Relatively pure F291 and F347 were obtained via the combination of hot-injection technology with purification treatment and were further characterized using mass spectroscopy, infrared spectroscopy, fluorescence spectroscopy, transmission electron microscopy, and X-ray powder diffraction. F291 and F347 are speculated to be [(Zn7Se7)(OLA)2(OA)] (OLA = oleylamine, OA = octylamine) and [(Zn16Se15)(OLA)7], respectively, by analyzing the corresponding mass and the infrared and absorption spectra; both emit narrow exciton fluorescence with relatively small stokes shift of 9 and 2 nm, respectively. Ultrafine ZnSe nanorods with a diameter of about 1.7 nm formed via oriented attachment of F347 were observed using transmission electron microscopy. Fatty amine−H2Se complex has been demonstrated to be a simple, phosphine-free, low-cost, and effective selenium precursor for the synthesis of ZnSe MSQDs or regular quantum dots (RQDs).
ZnSe:Mn/ZnS core–shell nanocrytals were successfully synthesized via a nucleation-doping strategy assisted with a low-toxicity, high-reactivity, and organic soluble selenium precursor in oleyamine. The as-prepared ZnSe:Mn/ZnS nanocrytals were then investigated by transmission
electron microscopy (TEM), X-ray powder diffraction (XRD), ultraviolet-visible (UV-Vis) absorption spectroscopy, and photoluminescence (PL) spectroscopy. All the results showed that the ZnSe:Mn/ZnS nanocrystals have good monodispersibility and high photoluminescence. Further systematic research
found that injection temperature of 250 °C, three ZnS layers, and Mn doping concentration of 2% are the optimal parameters for the synthesis of high luminescence ZnSe:Mn/ZnS nanocrystals. Additionally, these ZnSe:Mn nanocrystals exhibit temperature- and magnetic field-dependent optical
properties, which show great potential in the application of temperature and magnetic field sensing.
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