Inter-layer and Intra-layer Heat Transfer in Bilayer/Monolayer Graphene van der Waals Heterostructure: Is There a Kapitza Resistance Analogous?

TL;DR

This study investigates heat transfer mechanisms in bilayer and monolayer graphene heterostructures, revealing non-equilibrium conditions and challenging the applicability of Kapitza resistance concepts at the nanoscale.

Contribution

The paper provides the first detailed molecular dynamics analysis of inter- and intra-layer heat transfer in bilayer/monolayer graphene, comparing results with continuum models.

Findings

No fully developed thermal equilibrium between layers.

Temperature drop at the interface is not due to Kapitza resistance.

Increasing system length reduces non-equilibrium region.

Abstract

Van der Waals heterostructures have exhibited interesting physical properties. In this paper, heat transfer in hybrid coplanar bilayer/monolayer (BL-ML) graphene, as a model layered van der Waals heterostructure, was studied using non-equilibrium molecular dynamics (MD) simulations. Temperature profile and inter- and intra-layer heat fluxes of the BL-ML graphene indicated that, there is no fully developed thermal equilibrium between layers and the drop in average temperature profile at the step-like BL-ML interface is not attributable to the effect of Kapitza resistance. By increasing the length of the system up to 1 $\mu$m in the studied MD simulations, the thermally non-equilibrium region was reduced to a small area near the step-like interface. All MD results were compared to a continuum model and a good match was observed between the two approaches. Our results provide a useful understanding of heat transfer in nano- and micro-scale layered 2D materials and van der Waals heterostructures.