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Substrate effects on quasiparticles and excitons in graphene nanoflakes
The effects of substrate on electronic and optical properties of triangular
and hexagonal graphene nanoflakes with armchair edges are investigated by using
a configuration interaction approach beyond double excitation scheme. The
quasiparticle correction to the energy gap and exciton binding energy are found
to be dominated by the long-range Coulomb interactions and exhibit similar
dependence on the dielectric constant of the substrate, which leads to a
cancellation of their contributions to the optical gap. As a result, the
optical gaps are shown to be insensitive to the dielectric environment and
unexpectedly close to the single-particle gaps.Comment: 4 pages, 4 figure
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