Effect of Grain Boundaries on Thermal Transport in Graphene

TL;DR

This study examines how grain boundaries, line defects, and chirality affect thermal transport in graphene, revealing that defect type and grain size significantly influence thermal conductivity at room temperature.

Contribution

The paper provides a detailed analysis of the impact of various defects and grain boundary structures on graphene's thermal conductance using non-equilibrium Green's functions.

Findings

Single grain boundaries reduce thermal transmission to 50-80% of ballistic conductance.

Line defects with octagon defects have lower thermal transmission than pentagon-heptagon defects.

Thermal conductivity decreases notably for grain sizes below a few hundred nanometers.

Abstract

We investigate the influence of grain boundaries (GBs), line defects (LDs), and chirality on thermal transport in graphene using non-equilibrium Green's functions. At room temperature the ballistic thermal conductance is ~4.2 GW/m^2/K, and single GBs or LDs yield transmission from 50-80% of this value. LDs with carbon atom octagon defects have lower thermal transmission than GBs with pentagon and heptagon defects. We apply our findings to study the thermal conductivity of polycrystalline graphene for practical applications, and find that the type and size of GBs play an important role when grain sizes are smaller than a few hundred nanometers.