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.
Thermoelectric technology generates electricity from waste heat, but one
bottleneck for wider use is the performance of thermoelectric materials.
Manipulating the configurational entropy of a material by introducing different
atomic species can tune phase composition and extend the performance optimization
space. We enhanced the figure of merit (zT) value to
1.8 at 900 kelvin in an n-type PbSe-based high-entropy material formed by
entropy-driven structural stabilization. The largely distorted lattices in this
high-entropy system caused unusual shear strains, which provided strong phonon
scattering to largely lower lattice thermal conductivity. The thermoelectric
conversion efficiency was 12.3% at temperature difference
ΔT = 507 kelvin, for the fabricated segmented module
based on this n-type high-entropy material. Our demonstration provides a paradigm
to improve thermoelectric performance for high-entropy thermoelectric materials
through entropy engineering.
Cubic GeTe thermoelectrics have been historically focused on, while this work utilizes a slight symmetry-breaking strategy to converge the split valence bands, to reduce the lattice thermal conductivity and therefore realize a record thermoelectric performance, all enabled in GeTe in a rhombohedral structure. This not only promotes GeTe alloys as excellent materials for thermoelectric power generation below 800 K, but also expands low-symmetry materials as efficient thermoelectrics.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.