Optimized Interface Engineering Enhances Carrier and Phonon Scattering for Superior Thermoelectric Performance in Yb-Filled Skutterudites

Thermoelectric (TE) performance in materials is often constrained by the strong coupling between carrier and phonon transport, necessitating trade-offs between electrical and thermal properties that limit improvements in the figure of merit (<i>zT</i>). Herein, a novel strategy is proposed to achieve simultaneous energy filtering and enhanced phonon scattering, effectively optimizing the TE properties of CoSb₃-based skutterudites. By introducing Cu₂Te nanoprecipitates into the Yb_0.3Co₄Sb₁₂ matrix, interfacial barriers are formed, which selectively filter low-energy charge carriers, significantly improving the Seebeck coefficient while maintaining high carrier mobility. As a consequence, a substantial enhancement of the power factor occurs. Furthermore, the multiscale precipitates inhibit grain boundary migration, leading to grain refinement, and effectively scatter phonons, consequently decreasing the lattice thermal conductivity. These synergistic improvements in electronic and phonon transport yield a peak <i>zT</i> of ∼1.47 at 823 K for the Yb_0.3Co₄Sb₁₂ + 0.5%Cu₂Te sample. Furthermore, a fabricated 7-pair TE module attains a maximum conversion efficiency of ∼6.1% under a temperature difference of 400 K. This work introduces a straightforward and effective approach for designing high-performance TE material systems through the collaborative tuning of electrical and thermal properties.