Comparative Thermal Conductivity of Transition Metal Dichalcogenide (TMD) MX2 (M=MO, W; X=S, TE) Bilayers:Amolecular Dynamic Study

Abstract

Hetero bilayers composed of two-dimensional transition metal dichalcogenides demonstrate remarkable performance in nanoscale electronic devices through the vertical stacking of individual layers. Nanotechnology has been primarily advanced by the emergence of two dimensional materials. Therefore, it is crucial for materials researchers to offer accurate descriptions of these materials specific to their intended applications. This material may be examined using two standard methodologies. Classical Mechanics and Density Functional Theory (DFT) served as two examples of theoretical models. This study aims to evaluate thermal conductivity using Molecular Dynamics (MD) simulation. The simulation utilizes the LAMMPS program. Interatomic potentials, such as the Lennard-Jones and Stillinger-Weber potentials, are employed to obtain intermediate results. This study investigates the in-plane thermal conductivities of MoTe2–MoTe2, MoTe2–WS2, and WTe2–WTe2 hetero bilayers through nonequilibrium molecular dynamics simulations. This study explicitly examines the impacts of system size and temperature-dependent interactions. The analysis indicates that as temperature increases from 100 to 500 K, thermal conductivity decreases in proportion to the rise in thermal radiation. Moreover, a reduction in system length results in decreased heat conductivity and radiation across all temperature ranges. Adjusting the system's breadth, provided that its heat conductivity remains largely unchanged within acceptable limits. The MoTe2-MoTe2 homo bilayer exhibited reduced thermal conductivity at elevated temperatures due to enhanced phonon-phonon scattering. A more significant reduction in the MoTe₂-WS₂ hetero bilayer was noted, attributed in part to phonon mismatch and interface scattering. The reduction becomes increasingly subtle with rising temperatures. The low thermal conductivity in the WTe₂-WTe₂ pairing is due to its composition of heavier atomic elements and specific interlayer bonds, which result in increased phonon anharmonicity and scattering. At high temperatures, heat transport was influenced by system dynamics and phonon spectra. This research elucidates the influence of temperature, system dynamics, and structural properties on the modulation of thermal conductivity in transition metal dichalcogenide hetero bilayers. Therefore, it provides suggestions for altering their exceptional thermal properties relevant to thermoelectric and nanoelectronics applications.