Multiple Families of Magic-Sized ZnSe Quantum Dots via Noninjection One-Pot and Hot-Injection Synthesis

摘要

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 [(Zn1(iSei5)(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).