Enhanced thermoelectric properties of armchair graphene nanoribbons with defects and magnetic field

We have investigated the thermoelectric properties of armchair graphene nanoribbons with defects and magnetic field by using non-equilibrium Green's function method. For perfect armchair graphene nanoribbons, it is shown that with its width increasing, the maximum of the figure of merit ZT is monotonously decreased while the phononic thermal conductance increases linearly. In the presence of defects, the phononic thermal conductance decreases monotonously with the defect number increasing. Interestingly, the maximum of ZT values is proportional to the defect number in longitudinal direction, but inversely proportional to that in transversal direction. In the presence of magnetic field, very remarkable enhancement of ZT value is further obtained at the bottom of conduction band.