▎ 摘　　要

Graphene quantum dots (GQDs) are promising semiconducting materials for practical applications. Chemical functionalization of GQD edges is a strategy to increase their solubility and processability and to modify their optical properties. Such functionalization has a twofold effect on the electronic structure, both attributed to electronic spatial localization. The first is relevant to the introduction of electronegative species, whereas the second effect modifies the electron wave function spatial distribution through the conformational changes of geometry of the otherwise planar GQD backbone. Our computational study shows that functionalization with a weakly electronegative chlorine functional group induces small red-shifts due to the localization of excitonic states around the defect site. Groups with strong electron inducting ability such as nitro introduce stronger red-shifts. In both cases, the planar geometry of the pristine sheet is preserved when functionalization is performed at only a single site. However, functionalizing at multiple sites around the edge results in warping of the geometry of the GQD, leading to stronger electronic localizations and the largest red-shifts. This observation suggests the utility of controlling the planar geometry as a new strategy for chemically modifying 2-dimensional nanomaterials toward optical tuning.