Thermoelectric properties of finite graphene antidot lattices

TL;DR

This study investigates the electronic and thermal transport properties of finite graphene antidot lattices, showing rapid convergence to bulk behavior and highlighting how antidot shape and edge configuration influence thermoelectric efficiency.

Contribution

It provides the first detailed analysis of how finite size and edge shape affect thermoelectric properties in graphene antidot lattices.

Findings

Transport properties converge quickly with lattice length (~6 units).

ZT can exceed 0.25, depending on antidot edge shape.

Zigzag edges reduce ZT by an order of magnitude compared to armchair edges.

Abstract

We present calculations of the electronic and thermal transport properties of graphene antidot lattices with a finite length along the transport direction. The calculations are based on a single orbital tight-binding model and the Brenner potential. We show that both electronic and thermal transport properties converge fast toward the bulk limit with increasing length of the lattice: only a few repetitions (~6) of the fundamental unit cell are required to recover the electronic band gap of the infinite lattice as a transport gap for the finite lattice. We investigate how different antidot shapes and sizes affect the thermoelectric properties. The resulting thermoelectric figure of merit, ZT, can exceed 0.25, and it is highly sensitive to the atomic arrangement of the antidot edges. Specifically, hexagonal holes with pure zigzag edges lead to an order-of-magnitude smaller ZT as compared to pure armchair edges. We explain this behavior as a consequence of the localization of states, which predominantly occurs for zigzag edges, and of an increased splitting of the electronic minibands, which reduces the power factor.