Ultrahigh thermoelectric power factor achieved in Yb filled CoSb3 skutterudites through additional Al doping

Abstract

Cage-like CoSb3 skutterudites has received widespread attentions due to its low cost, moderate band gap and nearly independent electron–phonon regulation. Unfortunately, recent researches revealed that external fillers occupying the icosahedral voids of Co-Sb framework might cause localized lattice distortion and strain which put extra difficulty for charge carrier transport. Here, we took use of additional Al atoms with smaller atomic radii to substitute Sb atoms in Yb single filled CoSb3 for the purpose of alleviating the local strain cause by Yb filling. It was found that trace amount of additional Al doping can significantly improve the carrier mobility from 33.9 cm2V1s−1 for Yb0.25Co4Sb12 to 49.8 cm2V-1s−1 for Al0.03Yb0.25Co4Sb12, resulting in an ultrahigh power factor of 72.0 μWcm-1K−2 at 873 K in the later sample. Our findings might shed light on future studies on optimizing the thermoelectric performance of CoSb3-based skutterudites and other material systems.