Preparation and characterization of ZnSe quantum dots by the cation-inverting-injection method in aqueous solution

Abstract

ZnSe quantum dots (QDs) were synthesised by the cation-inverting-injection method in aqueous solution, using thioglycolic acid (TGA) as a stabiliser, zinc acetate dihydrate (Zn(OAc)2·2H2O) and sodium hydrogen selenide (NaHSe) as precursors solution. The morphology structure and optical properties of ZnSe QDs were characterised by transmission electron microscopy (TEM), X-ray powder diffraction (XRD), X-ray photoelectron spectroscopy (XPS), energy dispersive X ray spectrometer (EDS), photoluminescence (PL) and UV–visible absorption spectra. The experimental results indicate that the as-synthesised ZnSe QDs with the average size of 4.1 ± 0.2 nm were zinc blende cubic crystal structure and approximate spherical shape. PL spectra were mainly the contribution of excitonic emission. The excitonic emission peak could be tuned by changing the refluxing time, the molor ratios of Zn2+/HSe− (nZn2+/nHSe− ratios), the concentration of Zn2+/HSe− (CZn2+/CHSe− ratios) and pH value. Under the optimal conditions, the strong PL peak located about 397 nm and ZnSe QDs with the fitted average lifetime of 25.1 ns reveals the strong deep-blue fluorescence.