Dimensional crossover and enhanced thermoelectric efficiency due to broken symmetry in graphene antidot lattices

TL;DR

This paper explores how broken symmetry in graphene antidot lattices induces a dimensional crossover to 1D electronic behavior, significantly enhancing thermoelectric efficiency with potential applications across 2D materials.

Contribution

It demonstrates that anisotropic GALs exhibit a dimensional crossover leading to improved thermoelectric performance and longer electron mean free paths, a novel nanostructuring strategy.

Findings

Dimensional crossover manifests as transmission plateaus characteristic of 1D systems.

Thermoelectric figure of merit, zT, can reach 0.9 at room temperature.

Anisotropic GALs have longer mean free paths than isotropic ones.

Abstract

Graphene antidot lattices (GALs) are two-dimensional (2D) monolayers with periodically placed holes in otherwise pristine graphene. We investigate the electronic properties of symmetric and asymmetric GAL structures having hexagonal holes, and show that anisotropic 2D GALs can display a dimensional crossover such that effectively one-dimensional (1D) electronic structures can be realized in two-dimensions around the charge neutrality point. We investigate the transport and thermoelectric properties of these 2D GALs by using non-equilibrium Green function (NEGF) method. Dimensional crossover manifests itself as transmission plateaus, a characteristic feature of 1D systems, and enhancement of thermoelectric efficiency, where thermoelectric figure of merit, $zT$, can be as high as 0.9 at room temperature. We also study the transport properties in the presence of Anderson disorder and find that mean free paths of effectively 1D electrons of anisotropic configuration are much longer than their isotropic counterparts. We further argue that dimensional crossover due to broken symmetry and enhancement of thermoelectric efficiency can be nanostructuring strategy virtually for all 2D materials.