Ab-initio calculation of electronic and optical properties of nitrogen and boron doped graphene nanosheet

Graphene nanosheet has been doped with nitrogen, boron and nitrogen-boron pair of different concentrations. Modifications of electronic and optical properties due to nitrogen, boron and nitrogen-boron codoping in graphene nanosheet have been explored in the frame work of ab-initio density functional theory. Band gap opening has been observed and besides, its magnitude increases with the doping concentration of three different species of adatoms. The static dielectric constant in the long wave length limit for parallel polarization of electric field increases with the doping concentration, whereas for perpendicular polarization it remains almost constant with respect to the doping concentration and specific types. Moreover, in case of nitrogen doped systems, a new electron energy loss spectra peak emerges around ∼2.4 eV for parallel polarization of applied external electric field vector. This peak height increases with the doping concentration. The maximum value of the reflectivity is enhanced with nitrogen concentration while for boron and nitrogen-boron pair concentration, a decreasing tendency is noticed.