Reduction in Thermal Conductivity of Monolayer MoS2 by Large Mechanical Strains for Efficient Thermal Management

TL;DR

This study experimentally measures how large mechanical strains significantly reduce the in-plane thermal conductivity of monolayer MoS2, providing crucial insights for thermal management in flexible electronics.

Contribution

First experimental measurement of MoS2's thermal conductivity under large mechanical strain using a direct optothermal Raman technique.

Findings

Thermal conductivity drops by approximately 62% at 6.3% tensile strain.

Thermal transport properties vary with mechanical strain in a strain-dependent manner.

Provides new data on 2D materials' thermal behavior under large strains.

Abstract

Two dimensional (2D) materials such as graphene and transition metal dichalcogenides (TMDC) have received extensive research interests and investigations in the past decade. In this research, we report the first experimental measurement of the in plane thermal conductivity of MoS2 monolayer under a large mechanical strain using optothermal Raman technique. This measurement technique is direct without additional processing to the material, and MoS2's absorption coefficient is discovered during the measurement process to further increase this technique's precision. Tunable uniaxial tensile strains are applied on the MoS2 monolayer by stretching a flexible substrate it sits on. Experimental results demonstrate that, the thermal conductivity is substantially suppressed by tensile strains: under the tensile strain of 6.3%, the thermal conductivity of the MoS2 monolayer drops approximately by 62%. A serious of thermal transport properties at a group of mechanical strains are also reported, presenting a strain dependent trend. It is the first and original study of 2D materials' thermal transport properties under a large mechanical strain, and provides important information that the thermal transport of MoS2 will significantly decrease at a large mechanical strain. This finding provides the key information for flexible and wearable electronics thermal management and designs.