Dynamic in situ Control of Heat Rectification in Graphene Nano Ribbons using Electric Field-induced Strain

TL;DR

This paper demonstrates that applying an electric field-induced strain to split a graphene nano-ribbon into unequal sections can dynamically control heat rectification, achieving up to 60% enhancement and polarity switching.

Contribution

It introduces a simple method to control heat rectification in graphene via external force, eliminating complex nano-patterning for tunable thermal diode functionality.

Findings

Rectification ratio increased by up to 60%.

Polarity of heat flux can be switched on-the-fly.

Method simplifies fabrication of thermally rectifying devices.

Abstract

An increasing number of papers propose routes to implement thermal counterparts of electronic rectification. These schemes are mainly based on combinations of crystal anharmonicity and broken mirror symmetry. With respect to graphene, proposals pivot around shape asymmetry induced by using hetero-structures of nano-patterned or defected sections of pristine graphene. Using Molecular Dynamics (MD) we show that it suffices to split a graphene nano-ribbon into two unequal strained sections using external force which leads to large asymmetry in the forward and reverse heat fluxes. We find that the corresponding rectification ratio is enhanced by up to 60 %. Also, and more importantly, the polarity is controllable on-the-fly, i.e. by changing the position where force is applied. Based upon our results we propose a thermo-electric device which obviates the complex nano-patterning and lithography required to pattern graphene every time a new rectification value or sign is sought for, opening a route to simpler fabrication and characterization of phononic phenomena in 2D materials.