Lattice Thermal Transport in Two-Dimensional Alloys and Fractal Heterostructures

TL;DR

This paper uses molecular dynamics simulations to study how different structural features in two-dimensional MoSe2-WSe2 systems affect their thermal conductivity, providing insights for designing materials with tailored heat transport properties.

Contribution

It introduces a computational approach to analyze thermal transport in 2D alloys and fractal heterostructures, revealing how interfaces and defects influence phonon propagation.

Findings

Distinct effects of defects and interfaces on phonon transport.

Fractal structures enable highly tunable thermal conductivities.

Potential applications in thermal management and thermoelectrics.

Abstract

Engineering thermal transport in two dimensional materials, alloys and heterostructures is critical for the design of next-generation flexible optoelectronic and energy harvesting devices. Direct experimental characterization of lattice thermal conductivity in these ultra-thin systems is challenging and the impact of dopant atoms and hetero-phase interfaces, introduced unintentionally during synthesis or as part of deliberate material design, on thermal transport properties is not understood. Here, we use non-equilibrium molecular dynamics simulations to calculate lattice thermal conductivity of (Mo|W)Se$_2$ monolayer crystals including Mo$_{1-x}$W$_x$Se$_2$ alloys with substitutional point defects, periodic MoSe$_2$|WSe$_2$ heterostructures with characteristic length scales and scale-free fractal MoSe$_2$|WSe$_2$ heterostructures. Each of these features has a distinct effect on phonon propagation in the crystal, which can be used to design fractal and periodic alloy structures with highly tunable thermal conductivities. This control over lattice thermal conductivity will enable applications ranging from thermal barriers to thermoelectrics.