Thermal transport in grain boundary of graphene by non-equilibrium Green’s function approach

Abstract

A method of combining lattice dynamics through the Brenner potential [D. W. Brenner et al., J. Phys.: Condens. Matter 14, 783 (2002)] with phonon transport through non-equilibrium Green’s function approach is applied to calculate the thermal conductance of graphene grain boundaries. The results show that all types of grain boundaries offer excellent thermal conductivity, in contrast to electronic transport which is structure-dependent. Zigzag-oriented symmetric grain boundaries present the highest thermal conductance, with weak dependence on the crystal alignment angle of graphene domains. The thermal conductance of grain boundaries increases while thermal ballisticity decreases with temperature. The out-of-plane mode is dominant in thermal conductivity of graphene grain boundaries.