Optical properties of α-, β-, γ-, and 6,6,12-graphyne structures: First-principle calculations

We have investigated optical properties of α-, β-, γ-, and 6,6,12-graphyne structures using first-principle calculations. In our calculations, the dielectric function, reflectivity, and absorption coefficient are calculated under both parallel and perpendicular electric field polarizations. Similar to graphene, graphynes are shown to exhibit a structure with broad frequency photoresponse. Remarkably, the results show that the optical spectra of all these graphynes are anisotropic under these two polarizations, i.e., all these graphynes have strong reflectivity in low frequency region under the parallel polarization, but very weak reflectivity under the perpendicular polarization. Moreover, the absorption spectra of all these graphynes under the parallel polarization exhibit high values ranging from the far infrared region to the ultra-violet one. All of these features of graphynes indicate that graphynes would be good potential materials for optoelectronics.