First-Principles study of high-temperature thermoelectric performance induced by hydrogenation of ZnAs and CdAs monolayers

Document Type

Article

Publication Date

9-1-2025

Abstract

Motivated by the improved electronic properties of the isostructural hydrogenated ZnSb monolayers, we investigate the thermoelectric efficiency in the hydrogenated ZnAs and CdAs monolayers (i.e., ZnAsH and CdAsH) at temperatures of 300 K and 900 K using Boltzmann transport theory while accounting for multiple carrier scattering mechanisms. Our results reveal that hydrogenation modifies the band structures of ZnAsH and CdAsH, inducing a transition from metallic to semiconducting behavior (1.89 eV for ZnAsH and 1.23 eV for CdAsH. The cohesive energy, formation energy, phonon spectrum, ab initio molecular dynamics (AIMD), and elastic constants confirm their robust stability. The electronic transport analysis shows that p-type ZnAsH and CdAsH exhibit high Seebeck coefficient of 225.42μV/K and 409.45μV/K respectively, along with high electrical conductivity. Small group velocity, strong anharmonicity, and high scattering rates lead to ultralow lattice thermal conductivities of 3.36(3.74) W/mK for the ZnAsH monolayer and 0.23(0.35) W/mK for the CdAsH monolayer in the x(y) directions. The electronic part of the thermal conductivity is consistent with predictions from the Wiedemann–Franz law. Combining the excellent electronic transport with ultralow lattice thermal conductivity, we achieve optimal ZTs of 0.53 for ZnAsH and 3.72 for CdAsH in the x-direction. These findings suggest that hydrogenated monolayers are promising candidates for thermoelectric (TE) technology.

Publication Title

Surfaces and Interfaces

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