Thermal Transport in Turbostratic Multilayer Graphene

TL;DR

This study investigates how turbostratic stacking faults in multilayer graphene significantly reduce its in-plane thermal conductivity, with detailed analysis linking the turbostratic content to thermal transport properties.

Contribution

It provides a quantitative analysis of the impact of turbostratic single-layer graphene on thermal conductivity using Raman and electron diffraction techniques.

Findings

Thermal conductivity decreases exponentially with turbostratic content.

A 1% turbostratic content reduces conductivity by a factor of 2.59.

At 19% turbostratic content, conductivity drops by an order of magnitude.

Abstract

The presence of twist angles between layers of two-dimensional materials has a profound impact on their physical properties. Turbostratic multilayer graphene is a system containing a distribution of rotational stacking faults, and these interfaces also have variable twist angles. In this work, we examine the influence of turbostratic single-layer graphene content on the in-plane thermal conductivity of a defect free multilayer graphene system with low defect density. Detailed Raman mode analysis is used to quantify the content of turbostratic single-layer graphene in the system while complementing insight is obtained from selected area electron diffraction studies. Thermal transport in these systems is investigated with Raman optothermal technique supported with finite element analysis simulations. Thermal conductivity of AB-stacked graphene diminishes by a factor of 2.59 for 1% of turbostratic single-layer graphene content, while the decrease at 19% turbostratic content is by an order in magnitude. Thermal conductivity broadly obeys the relation, $\kappa$ $\propto$ exp(-F), where F is the fraction of turbostratic single-layer graphene content in the system