The effect of four-phonon scattering on the lattice thermal conductivity of Janus WSSe and WS2 monolayers

Abstract

Recent research indicates that four-phonon (4ph) scattering plays an important role in influencing the lattice thermal conductivity (κ_l) of materials. Including this 4ph scattering mechanism can lead to more precise predictions of κ_l and enable better control of heat transport through phonon engineering. In this paper, the κ_l of WS₂ and Janus WSSe monolayers were calculated by first-principles calculations combined with the Boltzmann transport equation. The κ_l of WS₂ and WSSe monolayers at 300 K are found to be 91.10 W m^-1 K^-1 and 50.19 W m^-1 K^-1, respectively, when 4ph scattering is considered. These results represent reductions of 37.31% and 25.16% compared to predictions derived solely from three-phonon (3ph) scattering models. Additionally, when 4ph scattering is included, the contribution of the ZA mode to the κ_l in WS₂ and WSSe monolayers is significant reduced, primarily due to the reflection symmetry selection rule. The effects of the group velocity, mode Grüneisen parameter, phase space, and scattering rate of the 3ph and 4ph scattering processes are also analyzed in the article.