Tuning optical excitations of graphene quantum dots through selective nitrogen doping

Our research has revealed that the nitrogen doping configuration has a significant impact on the absorption properties and band gap of nitrogen doped graphene quantum dots (NGQDs). By analyzing the composition and character of optical transitions, we have observed that nitrogen doping causes a redistribution of oscillator strength between significant peaks and the emergence of new optical features. These changes lead to broken molecular orbital degeneracies, optical peak splitting, and activation of dark states in the visible to near-infrared (NIR) region. These findings shed light on the mechanisms that govern alterations in the spectral properties of NGQDs within the visible and near-infra red (NIR) absorption bands. Furthermore, selective manipulation of optoelectronic properties via distinct N-doping patterns could pave the way for the development of novel optoelectronic nanodevices and functional materials.