Transport properties of zigzag graphene nanoribbons with oxygen edge decoration

Using the density functional theory in combination with the nonequilibrium Green’s function method, we investigate the transport properties of zigzag-edged graphene nanoribbons (ZGNRs) with oxygen edge decoration (passivated by the ketone (CO) or ether (C–O–C), denoting as ZGNR-CO and ZGNR-C2O, respectively). We find that both ZGNR-CO and ZGNR-C2O induce the semiconductor-metal transition and enhance the transmission conductance within ‘transparent’ electrodes. However, sandwiched by Au (111) electrodes, Au∣ZGNR − CO∣Au enhances the transport properties while Au∣ZGNR − C2O∣Au depresses the transport properties in comparison with Au∣ZGNR − H∣Au. It is found that the transport properties of the edge oxidized ZGNRs within Au (111) electrodes depend on the electronic states around the Fermi level which determine the number of the effective transport channels. The states of Au∣ZGNR − CO∣Au are delocalized on the edge oxygen atoms as well as the inner edge carbon atoms, introducing extra transport channels. Moreover, in comparison with Au∣ZGNR − H∣Au, the effective transport channels of Au∣ZGNR − CO∣Au increase at given applied bias. However, the states of Au∣ZGNR − C2O∣Au are localized on the ribbon, blocking the effective transport channels.

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► Edge-oxidization modulates the transport properties of ZGNRs.
► CO termination enhances the electronic transport.
► C–O–C termination depresses the electronic transport.