Anomalous enhancement of thermoelectric power factor by thermal management with resonant level effect

Abstract

Obtaining high thermoelectric performance has been the biggest historical challenge for thermoelectric power generation. Here, we propose a methodology for thermoelectric power factor enhancement: thermal management with resonant level effect for simultaneous increase of electrical conductivity σ and Seebeck coefficient S. Au crystals and Au impurities are introduced into SiGe. Therein, (1) highly-conductive Au crystals increased σ. (2) Au impurities brought about resonant level effect and phonon scattering, resulting in enhanced S and lowered thermal conductivity κ of SiGe. (3) This κ distribution control brings the focus of temperature difference on SiGe parts with lowered κ, resulting in the availability of the enhanced S of SiGe parts as effective S of the entire nanocomposite. Consequently, we achieved the highest S²σ at room temperature among SiGe-related materials ever reported. Electronic structure calculation and measurement support the existence of resonant levels, which enhances S and lowers κ. These results provide a new route to thermoelectric performance enhancement.