Low lattice thermal conductivity driven by weak interlayer interaction and acoustic–optical coupling in the SrZnSbF thermoelectric material

Abstract

The thermoelectric performance of the SrZnSbF compound is comprehensively evaluated using first-principles calculations and Boltzmann transport theory in present study. The electronic band structure shows that the SrZnSbF compound is semiconductor with a direct bandgap of 0.64 eV. A comprehensive evaluation of elastic modulus calculations, ab initio molecular dynamics simulations and the phonon dispersion confirmed that the SrZnSbF compound has excellent thermal and dynamic stabilities. The weak interlayer van der Waals forces between [Sr₂F₂]²⁺ and [Zn₂Sb₂]²⁻ layers, the distribution characteristics of electronic antibonding states near the Fermi level, and the strong acoustic–optical coupling in the low-frequency region of the phonon dispersion curves lead to the strong anharmonicity of the SrZnSbF compound, resulting in a low lattice thermal conductivity (1.68 W m⁻¹ K⁻¹) at 300 K. By combining multiple carrier scattering mechanisms, the thermoelectric performance of SrZnSbF compound is evaluated, and an optimal dimensionless figure of merit (ZT) of ∼1.93 (p-type) is achieved at 900 K. The current work not only reveals the thermoelectric enhancement mechanism of SrZnSbF compound by electron–phonon synergistic regulation, but also highlights the application potential of the SrZnSbF compound as a high-temperature thermoelectric material.