Engineering Anisotropy and K-Atom Rattling Vibration for Superior n-Type Thermoelectric Performance in KAuSe2

Abstract

This study reveals the structure-performance relationship of the thermoelectric material KAuSe2 through first-principles calculations and Boltzmann transport theory.Strong covalent bonds within the chain [AuSe2 ] and weak interlayer ionic interactions lead to pronounced anisotropic phonon and charge transport. K rattler acts as an efficient scattering center, strongly suppressing the lattice thermal conductivity (κL). A flat valence-band top favors a high Seebeck coefficient (S), which, combined with high electrical conductivity (σ) along the c-direction, yields a zT of 1.06 at 700 K in n-type KAuSe2 . This work clarifies the roles of structural anisotropy and K rattling, offering theoretical guidance for designing high-performance layered thermoelectrics.