First-principles studies the optical properties of defective-GQDs and -fullerene

Abstract

We demonstrate the size effect of quantum dots and discuss the effect of defect on the luminescence properties of graphene quantum dots (GQDs) and fullerene (C60) in this paper. Results show that the smaller the GQDs, the more difficult it is to prepared. The absorption peak of visible light region can be attained from large-size GQDs and small-size GQDs mainly show the luminescence performance of UV region. The band gap of GQDs become narrower and narrower with increasing size and adjusting symmetry. And then C60 (0.7 nm) with higher symmetry exhibits better optical and electronic conductivity. The defective GQDs and C60 have better adsorption capacity for functional group –OH and -NMP than non-defective structure. And the effect of defect and adsorbed functional group on the optical properties is clearly different, which C defect and functional group adsorption can improve its optical properties for large size GQDs and completely weaken its optical properties for C60.