Effect of Grain Boundaries on Thermal Transport in Graphene

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.