Edge currents and nanopore arrays in zigzag and chiral graphene nanoribbons as a route toward high-ZT thermoelectrics

We analyze electronic and phononic quantum transport in zigzag or chiral graphene nanoribbons (GNRs) perforated with an array of nanopores. Since local charge current profiles in these GNRs are peaked around their edges, drilling nanopores in their interior does not affect edge charge currents while drastically reducing the phonon heat current in sufficiently long wires. The combination of these two effects can yield highly efficient thermoelectric devices with maximum figure of merit ZT similar or equal to 5, at both liquid nitrogen and room temperature, achieved in similar to 1 mu m long zigzag GNRs with nanopores of variable diameter and spacing between them. Our analysis is based on the nonequilibrium Green's function formalism combined with the pi-orbital tight-binding Hamiltonian including up to third-nearest-neighbor hopping for an electronic subsystem, or with an empirical fifth-nearest-neighbor force-constant (5NNFC) model for a phononic subsystem. Additionally, we demonstrate that different empirical FC models typically overestimate the phonon conductance when compared to first-principles results.