Regulable preparation of the oxygen vacancy of ZnO QDs and their fluorescence performance

In this study, zinc oxide quantum dots (ZnO QDs) with good dispersity and stable fluorescence performance were prepared using the solvothermal method, which is simple, easy to control, and applicable to mass production. X-ray diffraction (XRD), field emission transmission electron microscopy (TEM), ultraviolet–visible spectroscopy (UV) and X-ray photoelectron spectroscopy (XPS) were adopted for the characterization, and the effect of alkali concentration and La doping amount on the formation of oxygen vacancy (OV) of ZnO QDs was investigated. The concentration of the oxygen vacancy (OV) of ZnO QDs can be effectively controlled by changing the alkali concentration or the La doping amount. The experiment results showed that the concentration of the OV of ZnO QDs first increases and then decreases as the alkali concentration rises, and it reaches the maximum when the OH−:Zn molar ratio is 1:1. The concentration of the OV of ZnO QDs first increases and then decreases with the increase of La doping amount, and it reaches the maximum when the La doping amount is 7 mol%. Meanwhile, the fluorescence emission intensity of ZnO QDs is in direct proportion to the concentration of OV, that is, the higher the concentration of the OV of ZnO QDs, the stronger the fluorescence emission intensity. In addition, 89.8% of the fluorescence intensity of the fluorescent quantum dots remained after 5 months at room temperature.