Realizing high figure of merit in heavy-band p-type half-Heusler thermoelectric materials

TLDR

Solid‑state thermoelectric technology offers a promising way to convert waste heat into electricity, and high operating temperatures and high figure of merit (zT) are essential for efficient power generation. The authors use high‑content Hf doping to simultaneously enhance the electrical power factor and reduce lattice thermal conductivity through increased point‑defect and electron–phonon scattering. The study reports a zT of ~1.5 at 1,200 K for p‑type FeNbSb half‑Heusler alloys and demonstrates an eight‑couple prototype module achieving 6.2 % efficiency and 2.2 W cm−2 power density at a 655 K temperature difference, underscoring the viability of low‑cost, robust high‑temperature thermoelectric modules.

Abstract

Abstract Solid-state thermoelectric technology offers a promising solution for converting waste heat to useful electrical power. Both high operating temperature and high figure of merit zT are desirable for high-efficiency thermoelectric power generation. Here we report a high zT of ∼1.5 at 1,200 K for the p -type FeNbSb heavy-band half-Heusler alloys. High content of heavier Hf dopant simultaneously optimizes the electrical power factor and suppresses thermal conductivity. Both the enhanced point-defect and electron–phonon scatterings contribute to a significant reduction in the lattice thermal conductivity. An eight couple prototype thermoelectric module exhibits a high conversion efficiency of 6.2% and a high power density of 2.2 W cm −2 at a temperature difference of 655 K. These findings highlight the optimization strategy for heavy-band thermoelectric materials and demonstrate a realistic prospect of high-temperature thermoelectric modules based on half-Heusler alloys with low cost, excellent mechanical robustness and stability.