Ultralow Thermal Conductivity in Two-Dimensional MoO<sub>3</sub>.

Tong, Zhen; Dumitrică, Traian; Frauenheim, Thomas · Nano Lett · 2021

basic_science · Level V

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Abstract

Monolayer molybdenum trioxide (MoO<sub>3</sub>) is an emerging two-dimensional (2D) material with high electrical conductivity but unexplored thermal conductivity. Using first-principles calculations and a Boltzmann transport theoretical framework, we predict a record low room-temperature phonon thermal conductivity (κ<sub>p</sub>) of 1.57 and 1.26 W/mK along the principal in-plane directions of the MoO<sub>3</sub> monolayer. The behavior is attributed to the combination of soft flexural and in-plane acoustic modes, which are coupled through the finite layer thickness, and to the strong bonding anharmonicity, which gives rise to significant 3- and 4-phonon scattering. These insights suggest new indicators for guiding the search of 2D materials with low κ<sub>p</sub> and motivates κ<sub>p</sub> measurements in MoO<sub>3</sub> and its applications as a thermoelectric and thermally protective material.