Influence of Oxidized Graphene Quantum Dots as Photosensitizers

In this study, we successfully prepared oxidatively functionalized graphene quantum dots (GQDs) to engineer the absorption band of a photoanode. By employing a facile hydrothermal process, we demonstrate the degree of intrinsic oxidation at the polar carbene edges of the GQDs, using Raman spectroscopy, X-ray photoelectron spectroscopy, and Fourier-transform infrared spectroscopy. The cyclic voltammetry results show that oxygen functional groups on the GQDs can change the highest occupied molecular orbital and lowest unoccupied molecular orbital levels. Dye-sensitized solar cells, with the GQDs dissolved in the dye, were evaluated in terms of their I-V characteristics and conversion efficiencies. The GQDs dissolved in the dye were easily attachable to TiO₂ porous particles, and also contributed to the photoelectric conversion efficiency.