Phonon transport in Janus monolayer MoSSe: a first-principles study

Area of Science:

• Condensed Matter Physics
• Materials Science
• Nanotechnology

Background:

• Transition Metal Dichalcogenide (TMD) monolayers possess unique physical properties, driving extensive research.
• Janus TMD monolayer MoSSe, featuring a S-Mo-Se structure, has been successfully synthesized.
• Understanding thermal transport in these novel materials is critical for device applications.

Purpose of the Study:

• To systematically investigate the phonon transport and lattice thermal conductivity (κL) in MoSSe monolayers.
• To compare the thermal properties of MoSSe with MoS2 and MoSe2 monolayers.
• To explore the influence of isotope scattering and size effects on κL.

Main Methods:

• First-principles calculations were employed to study MoSSe monolayers.
• The linearized phonon Boltzmann equation within the single-mode relaxation time approximation (RTA) was utilized.
• Phonon group velocities, lifetimes, and elastic properties were analyzed.

Main Results:

• MoSSe monolayers exhibit significantly lower κL than MoS2 and higher κL than MoSe2.
• The thermal sheet conductance of MoSSe monolayers is 342.50 W K⁻¹ at room temperature.
• Reduced phonon group velocities and shorter lifetimes in MoSSe contribute to lower κL compared to MoS2.

Conclusions:

• The thermal conductivity of MoSSe monolayers is governed by phonon transport dynamics.
• Isotope scattering reduces κL by 5.8%, while size effects can halve κL at ~110 nm characteristic length.
• Findings offer insights for thermal management in MoSSe for applications in thermoelectrics, thermal circuits, and nanoelectronics.