Exotic thermoelectric behavior in nitrogenated holey graphene

Combining first-principles approaches with the Boltzmann transport equation and semi-classical analysis we investigate the thermal conductivity k, thermopower S, electrical conductivity s, and carrier mobility m of newly synthesized nitrogenated holey graphene (NHG). Strikingly, the NHG possesses exceedingly high S and s but a fairly low lattice thermal conductivity kL, and therefore extraordinary thermoelectric properties, with a figure of merit zT even exceeding 5.0, are obtained in the n-type doped NHG. The outstanding thermoelectric behavior of NHG is attributed to its exotic atomic and electronic structure: (i) strong anharmonic phonon scattering results in a very low kL; (ii) flat bands around the Fermi level together with a large band gap cause high S; and (iii) conduction band dipping at the Brillouin zone center leads to a high electron mobility m and thus high s.