Thermal conductivity of monolayer MoS2, MoSe2, and WS2: interplay of mass effect, interatomic bonding and anharmonicity

Abstract

Phonons are essential for understanding the thermal properties in monolayer transition metal dichalcogenides. We investigate the lattice dynamics and thermodynamic properties of MoS₂, MoSe₂, and WS₂ by first principles calculations. The obtained phonon frequencies and thermal conductivities agree well with the measurements. Our results show that the thermal conductivity of MoS₂ is highest among the three materials due to its low average atomic mass. We also discuss the competition between mass effect, interatomic bonding and anharmonic vibrations in determining the thermal conductivity of WS₂. Strong covalent W–S bonding and low anharmonicity in WS₂ are found to be crucial in understanding its much higher thermal conductivity compared to MoSe₂.