Synergistic In and Ga Co-filling with Sb substitution in Co4Sb12 skutterudites: A beneficial compositing effect for high power factor

Abstract

We report a rare-earth–free multi-filling strategy to enhance the thermoelectric performance of Co₄Sb₁₂ skutterudites. Co-filling with In and Ga, along with partial Sb for Te substitution induces beneficial compositing effect, refines grain size, and tunes filler's solubility. An optimal In:Ga ratio, achieved in In_0.3Ga_0.1Co₄Sb_11.8Te_0.2, maximizes dodecahedral site occupancy and yields a high power factor (≈ 40 μWcm⁻¹ K⁻²) in the 300−600 K range, reaching values close to that of rare-earth–filled skutterudites.