Enhancing luminescence of ZnO quantum dots by PEG and oleic acid via a sol–gel method

PEG/oleic acid capped ZnO quantum dots were synthesized by a traditional sol–gel method. The XRD pattern, HRTEM image, FT-IR spectra and photoluminescence properties of the ZnO quantum dots were measured. Viscosities in the reaction with different content of PEG was also measured to discover the way PEG affects the reaction of ZnO quantum dots. PEG and oleic acid could enhance the emission intensity of ZnO quantum dots by cutting down their surface defects. The sample with the content of PEG-400 (n(PEG):n(Zn)) is 1.0:1 and the addition of oleic acid is 2.0 mL (for 0.01 mol ZnO) shows the strongest emission and excitation intensity. However, too much PEG would impede the reaction between Zn(Ac)2 and LiOH, which leads to the decreasing of the emission intensity.