Electronic and optical properties of boron and nitrogen pair co-doped 6,6,12-graphyne nanosheet

We investigate the electronic and optical properties of boron-nitrogen pair co-doped 6,6,12-graphyne nanosheets using first-principles calculations. For the electronic band structure, we find the band gap exhibits an even-odd effect with an increase in doping concentration. Exploring the optical properties, we calculate the dielectric function, reflectivity, and absorption coefficient under both parallel and perpendicular polarizations. Remarkably, the co-doped 6,6,12-graphyne shows a broad frequency photo-response. Under parallel polarizations, co-doping leads to a reduced static dielectric constant in the long wavelength limit. Furthermore, the reflectivity and absorption spectra show that the co-doped 6,6,12-graphyne nanosheets are highly sensitive to light from the infrared to the ultraviolet regimes. When doping concentration increases, the maximum reflectivity coefficient increases after an initial decrease under the longitudinal parallel polarization, in contrast to its oscillating behavior under the transverse parallel polarization. For all polarizations, the maximum absorption coefficient varies non-monotonically with doping concentration.