Unexpected large thermal rectification in asymmetric grain boundary of graphene

TL;DR

This study reveals a significant and unexpected thermal rectification effect in asymmetric grain boundaries of graphene, suggesting potential for simple, efficient thermal diodes using polycrystalline graphene.

Contribution

It demonstrates large thermal rectification in asymmetric graphene grain boundaries, a phenomenon not previously reported, with implications for thermal management devices.

Findings

Thermal rectification is direction-dependent in asymmetric graphene grain boundaries.

Thermal boundary resistance shows ultra-low temperature dependence.

Rectification effect increases with larger temperature differences.

Abstract

We have investigated the lattice thermal transport across the asymmetric tilt grain boundary between armchair and zigzag graphene by nonequilibrium molecular dynamics (NEMD). We have observed significant temperature drop and ultra-low temperature-dependent thermal boundary resistance. More importantly, we find an unexpected thermal rectification phenomenon. The thermal conductivity and Kapitza conductance is direction-dependent. The effect of thermal rectification could be amplified by increasing the difference of temperature imposed on two sides. Our results propose a promising kind of thermal rectifier and phonon diodes based on polycrystalline graphene without delicate manipulation of the atomic structure.