title: Excitonic absorption spectra in graphene nanoflakes: Tuning of exciton binding energy by dielectric environments.
abstract: By solving the Bethe-Salpeter equation within the Hartree-Fock formalism, we study the excitonic absorption spectra of graphene nanoflakes embedded in various dielectric environments. With the excitonic effects fully taken into account, the exciton binding energy as a function of the dielectric constant is found to be well described by a single scaling rule in which the scaling factor is found to vary slowly with the size of the nanoflakes. Furthermore, it is revealed that the exciton binding energy scales almost linearly with the on-site interaction energy and exhibits more sensitive dependence in smaller nanoflakes. Our results are found to agree well with the recent experiment.
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China.
authors.forename: Hao
authors.initials: H
authors.lastname: Wang
authors.affiliation: State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai, China and Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China.
authors.forename: Weidong
authors.initials: W
authors.lastname: Sheng