Theoretical research on thermoelectric properties of graphene nanorings

Based on the tight-binding approach and the nonequilibrium Green's function method, the thermoelectric performance of graphene nanoribbons (GNRs) and graphene rings are investigated systematically. Thermoelectric properties show substantial dependence on graphene structure. The maximum value of thermoelectric figure of merit (ZT) in perfect GNRs declines exponentially with the increase of width N except for metallic armchair GNRs with N=3i+2 (i is an integer). In graphene rings, the ZT value is enhanced dramatically at room temperature, which oscillates with perpendicular magnetic field due to Aharonov-Bohm effect. The significantly enhanced ZT value makes graphene ring a promising candidate for thermoelectric applications.