One step in-situ synthesis of Cu/Mn: ZnInSe quantum dots with enhanced luminescence and environmental stability

Abstract

A novel Cu/Mn: ZnInSe ternary quantum dots (QDs) was synthesized by one step in-situ hydrothermal method from low-cost inorganic salts and natural biomolecules. Based on the controlled L-cysteine capped ZnInSe QDs structure, Cu/Mn: ZnInSe QDs were synthesized by Cu and Mn co-doping. The effects of experimental variables such as ZnInSe QDs synthesis conditions and Cu/Mn doping ratio were systematically studied. The results show that the photoluminescence (PL) intensity of the co-doped ternary Cu/Mn: ZnInSe increases significantly by about 1.8 times, and the position of the fluorescence emission peak is redshifted. The mechanism of fluorescence enhancement was attributed to doped ions confined in the quantum dot lattice, providing new recombination centers for electrons and holes, and forming internal luminescent centers. The structures and morphologies of ZnInSe QDs and Cu/Mn: ZnInSe QDs have been confirmed by X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM) and X-ray powder diffraction (XRD), The effects of environmental impact factor (light, temperature, pH, H₂O₂) of ZnInSe QDs and Cu/Mn: ZnInSe QDs were studied by measuring the change in the PL intensity. It is also found out that Cu/Mn: ZnInSe QDs exhibit good stability under visible light, as well as certain acid resistance and oxidation resistance. Especially after doping, there is a significant improvement in high-temperature resistance performance. 120 % of the PL intensity can be remained after the temperature rises to 60 °C, Whilst less than 70 % is maintained for undoped ZnInSe QDs. These results would contribute to further understanding dopant-dependent interaction, and this new class of co-doped QDs with high uniform size, enhanced luminescence and environmental stability demonstrates a promising future to be applied in white LED and bio-tag.