Ultralow Thermal Conductivity in Two-Dimensional MoO3

Monolayer molybdenum trioxide (MoO3) 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 (kappa(p)) of 1.57 and 1.26 W/mK along the principal in-plane directions of the MoO3 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 kappa(p) and motivates kappa(p) measurements in MoO3 and its applications as a thermoelectric and thermally protective material.

Automated summary

Using first-principles calculations and theoretical framework, it was found that monolayer molybdenum trioxide has record low thermal conductivity due to soft flexural and in-plane acoustic modes combined with strong bonding anharmonicity. These insights can guide the search for 2D materials with low thermal conductivity and motivate measurements for potential applications in thermoelectricity and thermal protection.