Electronic, phononic, and thermoelectric properties of graphyne sheets

Electron, phonon, and thermoelectric transport properties of a-, b-, c-, and 6,6,12-graphyne sheets are compared and contrasted with those of graphene. a-, b-, and 6,6,12-graphynes, with direction dependent Dirac dispersions, have higher electronic transmittance than graphene. gamma-graphyne also attains better electrical conduction than graphene except at its band gap. Vibrationally, graphene conducts heat much more efficiently than graphynes, a behavior beyond an atomic density differences explanation. Seebeck coefficients of the considered Dirac materials are similar but thermoelectric power factors decrease with increasing effective speeds of light. gamma-graphyne yields the highest thermoelectric efficiency with a thermoelectric figure of merit as high as ZT = 0.45, almost an order of magnitude higher than that of graphene. (C) 2014 AIP Publishing LLC.