▎ 摘　　要

The photoluminescence quantum yield of graphene quantum dots (GQDs) is usually very low because the fast electron-hole recombination converts electronic energy into thermal energy. This problem can be addressed by controlling the surface chemistry of the GQDs through the manipulation of the oxidation configurations. The optoelectronic properties of GQDs functionalized with hydroxyl groups at different sites of the GQDs are investigated in this work using density-functional theory (DFT) and linear response time-dependent DFT calculations. We also calculated the non-radiative decay rates of GQDs with different oxidation configurations. Our results show that the center-oxidized configurations lead to a larger perturbation of the conjugated pi-system, reducing the band gap and the red-shift of the absorption spectra. The addition of solvent leads to red-shifts in the absorption spectra and increased intensities for some center-oxidized configurations. In contrast, only the red-shifts occur in the absorption spectra for the edge-oxidized configurations. Placement of the hydroxyl group in the basal plane of the GQD accelerates the non-radiative decay, while the placement of the hydroxyl group at the edges of the GQD suppresses the non-radiative decay. The current calculations shed light on the relationship between the surface chemistry and the photoluminescence efficiency of GQDs.