▎ 摘　　要

This work successfully traces the imprints of zigzag/armchair-edgemodification and site-selective functionalization by different chemicalspecies in dictating the structural, electronic, and optical propertiesof low-symmetry structural isomers of graphene quantum dots (GQDs).Our time-dependent density functional theory-based computations revealthat the electronic band gap reduction is greater for zigzag-edgefunctionalization than for armchair-edge modification by chlorineatoms. The computed optical absorption profile of functionalized GQDsexhibits an overall red shift with respect to their pristine counterpart,with the shift being more pronounced at higher energies. Markedly,the optical gap energy is regulated more substantially by zigzag-edgechlorine passivation while the armchair-edge chlorine functionalizationis more effective in altering the position of the most intense (MI)absorption peak. The MI peak energy is exclusively decided by thesignificant perturbation in the electron-hole distributionproduced by the structural warping of the planar carbon backbone realizedby edge-functionalization while the interplay between frontier orbitalhybridization and structural distortion governs the energies of theoptical gap. In particular, the enhanced tunability range of the MIpeak in comparison to the optical gap variation signals that the structuralwarping plays a more decisive role in modulating the MI peak characteristics.The energy of the optical gap and the MI peak along with the charge-transfercharacter of the excited states is critically dependent on the electron-withdrawingcapability and the site of the functional group. This comprehensivestudy is extremely crucial for promoting the application of functionalizedGQDs in designing highly efficient tunable optoelectronic devices.