Thermal conductivity across transition metal dichalcogenide bilayers

Area of Science:

• Materials Science
• Condensed Matter Physics
• Nanotechnology

Background:

• Transition metal dichalcogenides (TMDs) are layered materials with unique electronic and thermal properties.
• Understanding their thermal conductivity is vital for applications in electronics and thermoelectrics.

Purpose of the Study:

• To determine the cross-plane thermal conductivities of various transition metal dichalcogenide (M=Mo, W; X=S, Se) bilayers.
• To investigate the influence of atomic mass, lattice constant, and interlayer interactions on thermal transport.

Main Methods:

• Homogeneous nonequilibrium molecular dynamics simulations were employed.
• Phonon spectral analysis was used to understand heat transport mechanisms.
• Slack's formula was utilized for rationalizing thermal conductivity trends.

Main Results:

• Tungsten diselenide (WSe2) and molybdenum disulfide (MoS2) bilayers exhibited the lowest thermal conductivities, acting as effective insulators.
• Heterobilayer thermal conductivities approximated the average of their constituent homobilayers.
• Boundary scattering significantly influenced thermal transport, while spectral overlap had minimal impact.

Conclusions:

• The thermal conductivity of TMD bilayers is primarily governed by average atomic mass and Debye temperature, as predicted by Slack's formula.
• Interlayer interaction potentials, even when accurately modeled, have a minor effect on cross-plane thermal conductivity.
• The findings provide insights for designing materials with tailored thermal properties for advanced applications.