Optical response of graphene quantum dots in the visible spectrum: a combined DFT-QED approach

Abstract

We propose a model based on density functional theory (DFT) and quantum electrodynamics (QED) to study the dynamical characteristics of graphene quantum dots (GQDs). We assume the GQD edges are saturated with hydrogen atoms, effectively making it a polycyclic aromatic hydrocarbon (PAH) such as coronene. By combining the GQD spectrum calculated from a time-dependent DFT (TDDFT) with the dynamical behavior of a QD model derived from QED, we calculate the main optical characteristics of the GQD, such as its transition frequencies, the dipole moment associated with each of those transitions, life-time, and the population dynamics of the molecular levels. Owing to the close match between the simulated spectrum and experimental results, our DFT-QED model represents a significant contribution to research on quantum treatments of light-matter interactions in realistic 2D nanomaterials.