First-principles prediction of the thermal conductivity of two configurations of difluorinated graphene monolayer

Abstract

Lattice thermal conductivity (κ_L) plays a crucial role in the thermal management of electronic devices. In this study, we systematically investigate the thermal transport properties of monolayer fluorinated graphene using a combination of machine learning-based interatomic potentials and the phonon Boltzmann transport equation. At a temperature of 300 K, we find that the κ_L values for chair-configured fluorinated graphene monolayers are 184.24 W m⁻¹ K⁻¹ in the zigzag direction and 205.57 W m⁻¹ K⁻¹ in the armchair direction. For the boat configuration, the κ_L values are 120.45 W m⁻¹ K⁻¹ and 64.26 W m⁻¹ K⁻¹ in the respective directions. The disparities in κ_L between these two configurations predominantly stem from differences in phonon relaxation times, which can be elucidated by examining the Grüneisen parameters representing the degree of anharmonicity. A more in-depth analysis of bond strengths, as assessed by the crystal orbital Hamiltonian population, reveals that the stronger in-plane CC bonds in chair-configured fluorinated graphene monolayers are the primary contributors to the observed variations in anharmonicity.