How interlayer twist angles affect in-plane and cross-plane thermal conduction of multilayer graphene: A non-equilibrium molecular dynamics study

Graphene, a kind of emerging low dimensional carbon material, has admirable thermal properties with potential applications in the thermal management of aerospace and microelectronics fields. In recent studies, thermal properties of both conventional single-layer and multilayer graphene were extensively studied. However, few studies focused on that of multilayer graphene with twist angles, whose thermal properties are different from that of conventional graphene because of the existence of interlayer twist angles. Such knowledge gap hinders the potential applications. Therefore, the thermal conductivity of bilayer, 4-layers and 6-layer zigzag graphene with various twist angles is investigated utilizing non-equilibrium molecular dynamics at the typical temperature region in this study, and both in- and cross-plane thermal conductivity are investigated. The size of the studied graphene is 10 nm x 22 nm in the x-y plane, and the size in the z-direction depends on the number of layers. Moreover, the phonon vibrational density of state is also analyzed for mechanisms behind the thermal transport. The result indicates that a local maximum value can be found with the twist angle of 30 degrees for in-plane thermal conduction. The results also suggest that the highest thermal conductivity could be reached without any twist angles for both in and cross-plane conduction. The observation would provide an opportunity to study the characteristics of in-plane and cross-plane thermal transport of twisted multilayer graphene. (C) 2019 Elsevier Ltd. All rights reserved.