Asymmetric thermal transport by adjusting structural defects

Thermal rectification created by asymmetric structural defects within graphene was investigated via molecular dynamics simulations. This study aims to achieve innovative asymmetric thermal transport, where a structure allows for effective heat dissipation in one direction while insulating in the other direction along that same path. Asymmetric relaxation distance for phonons in nanoscale structures induces a difference in heat transfer depending on transport direction, enabling thermal rectification. Hole size and location are controlled to create different asymmetricity, and two sizes of graphene sheet are simulated to demonstrate the ballistic effect. Increase in degree of asymmetry, which results in a larger difference in relaxation, and smaller dimension produce more significant thermal rectification. In this research, thermal rectification of 10% was achieved in a single-layer graphene sheet of 41.5 × 11.0 nm² with a single hole with 4 nm of radius, which has an asymmetricity of 12%. This study suggests a feasible approach to create thermal rectification and enables its fine control, contributing to the development of phononic devices and enhancement of thermal system design for electronics.