Theoretical Prediction of the Monolayer Hf2Br4 as Promising Thermoelectric Material

Abstract

The stability, electronic structure, electric transport, thermal transport and thermoelectric properties of the monolayer Hf2Br4 are predicted by using first principle calculations combined with Boltzmann transport theory. The dynamic stability of the monolayer Hf2Br4 is verified by phonon band dispersion, and the thermal stability is revealed by ab initio molecular dynamics simulations. The electronic structure calculation indicates that the monolayer Hf2Br4 is an indirect band gap semiconductor with a band gap of 1.31 eV. The lattice thermal conductivity of the monolayer Hf2Br4 is investigated and analyzed on phonon mode level. The calculation results of the electric transport explore the excellent electric transport properties of the monolayer Hf2Br4. The thermoelectric transport properties as a function of carrier concentration at three different temperatures are calculated. The study indicates that the monolayer Hf2Br4 can be an alternative, stable two-dimensional material with potential application in the thermoelectric field.

Strain-Driven High Thermal Conductivity in Hexagonal Boron Phosphide Monolayer

“…The Grüneisen parameter γ is an important index to measure the strength of phonon anharmonicity (the larger the absolute value of γ, the stronger the phonon anharmonicity). − The γ of the h-BP monolayer under the strain of 0–8% is given in Figure a. Based on the discussion in the previous paragraphs, we mainly focus on the influence of strain on the γ of acoustic phonons (especially the phonons near the Γ point, that is, the phonons whose vibration frequency is close to 0 THz).…”

“…Next, the phonon lifetime τ of the h-BP monolayer under strain is studied. Generally, phonon anharmonicity affects the κ l by influencing the phonon lifetime. , Simultaneously, the scattering phase space P 3 reveals the possibility of scattering, contributing to τ. As shown in Figure b, the effect of strain on P 3 of the h-BP monolayer is slight.…”