Optimization of thermoelectric power factor and deviation from Mott's formula of edge-disordered semiconducting graphene nanoribbons

•We theoretically investigated the effects of edge disorder on the thermoelectric properties.•The power factor of a GNR exhibits a maximum at a certain length of the edge-disordered region.•As the edge disorder concentrations increase, both the maximum power factor and the optimal edge-disordered length decrease due to the Anderson localization.

The room-temperature thermoelectric properties of semiconducting graphene nanoribbons (GNRs) with edge disorder were computationally investigated. The thermoelectric power factor (PF) of edge-disordered GNRs (ED-GNRs) can be maximized by adjusting the ribbon length, Lg. For example, the PF of armchair-type ED-GNRs with an edge disorder concentration Cd of 5% has a maximum value of 16.2 mW/(m K2) at Lg = 146 nm and a chemical potential μ of −0.6 eV. The appearance of the maximum PF can be understood by a crossover phenomenon where electric conduction in an ED-GNR gradually changes from ballistic transport to Anderson localization as Lg increases. In addition, Mott's formula, which is well known as the relation between the Seebeck coefficient and electrical conductance, could not be applied to ED-GNRs within the Anderson localization regime.

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