Interfacial thermal resistance and thermal rectification between suspended and encased single layer graphene

Abstract

With molecular dynamics simulations, we systematically investigate interfacial thermal resistance between suspended and encased single layer graphene. Combining with lattice dynamics analysis, we demonstrate that induced by substrate coupling which serves as perturbation, the long wavelength flexural phonon mode in the encased graphene is significantly suppressed when compared with that in the suspended graphene. Therefore, at the interface between suspended and encased graphene, in-plane phonon modes can transmit well, whereas low frequency flexural phonon modes are reflected, leading to this nontrivial interfacial thermal resistance. The impacts of coupling strength, temperature, and size of the system on this type of interfacial thermal resistance are explored. More interesting, we find that thermal rectification can be realized in this inhomogeneous encased graphene structures with a thermal rectification efficiency of 40% at 50 K temperature difference. Our study provides insight to better understand thermal transport in two-dimensional materials and promising structures for practical thermal rectification devices.