▎ 摘　　要

The C-N bonding environment reduces the integrity of the graphene lattice, induces defect states into nitrogendoped graphene quantum dots (NGQDs), and significantly impacts the photoluminescence quantum yield of NGQDs. In the present work, we investigate non-radiative relaxation dynamics in pristine and N-doped GQDs based on Fermi's golden rule. Our results show that the N-doping perturbs the electron distribution of the frontier orbitals, which reduces the highest occupied molecular orbital (HOMO) - lowest unoccupied molecular orbital (LUMO) gaps and results in a redshift of the optical spectra of NGQDs compared to pristine GQD. In particular, the graphitic and pyridinic N create the midgap states but exhibit different effects on non-radiative decay in NGQDs. For the graphitic NGQD, the negative induction effect of graphitic N reduces the pi-electron densities, giving rise to exceptionally small electronic couplings, especially during the electron trapping step; consequently, it has a less efficient non-radiative decay than the pyridinic and pyrrolic NGQDs. In contrast, the large intramolecular and solvent reorganization energies associated with the electron trapping step in pyridinic NGQD create a very efficient electron-hole recombination channel through the hole trapping step, accelerating its nonradiative decay. Overall, this work advances our current understanding of the specific role of each N functionality in the non-radiative decay of NGQDs.