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Contributed by Ching-Wu Chu, October 24, 2016 (sent for review September 7, 2016; reviewed by Jing-Feng Li and Silke Paschen)
Significance
Thermoelectric technology can boost energy consumption efficiency by converting some of the waste heat into useful electricity. Heat-to-power conversion efficiency optimization is mainly achieved by decreasing the thermal conductivity in many materials. In comparison, there has been much less success in increasing the power factor. We report successful power factor enhancement by improving the carrier mobility. Our successful approach could suggest methods to improve the power factor in other materials. Using our approach, the highest power factor reaches ∼106 μW⋅cm−1⋅K−2 at room temperature. Such a high power factor further yields a record output power density in a single-leg device tested between 293 K and 868 K, thus demonstrating the importance of high power factor for power generation applications.
Abstract
Improvements in thermoelectric material performance over the past two decades have largely been based on decreasing the phonon thermal conductivity. Enhancing the power factor has been less successful in comparison. In this work, a peak power factor of ∼106 μW⋅cm−1⋅K−2 is achieved by increasing the hot pressing temperature up to 1,373 K in the p-type half-Heusler Nb0.95Ti0.05FeSb. The high power factor subsequently yields a record output power density of ∼22 W⋅cm−2 based on a single-leg device operating at between 293 K and 868 K. Such a high-output power density can be beneficial for large-scale power generation applications.
Footnotes
- ↵1To whom correspondence may be addressed. Email: cwchu{at}uh.edu, gchen2{at}mit.edu, or zren{at}uh.edu.
Author contributions: R.H. and Z.R. designed research; R.H. performed research; D.K., L.Z., Y. Lan, C.L., J.S., H.S.K., Y. Liu, and D.B. contributed new reagents/analytic tools; R.H., J.M., Q.J., G.C., and Z.R. analyzed data; and R.H., D.K., L.Z., D.B., C.-W.C., G.C., and Z.R. wrote the paper.
Reviewers: J.-F.L., Tsinghua University; and S.P., Vienna University of Technology.
The authors declare no conflict of interest.
This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1617663113/-/DCSupplemental.
High power factor and power density in NbFeSb
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- Physical Sciences
- Applied Physical Sciences
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- Sample Characterization
- Thermal Diffusivity and Specific Heat
- Band Structure and Bipolar Thermal Conductivity
- Grain Size Distribution
- Measuring Phonon MFP Distribution in Nb0.95Ti0.05FeSb
- Klemens Model
- Calculation of Efficiency and Power Density
- Measurement of Efficiency and Power Density
- Acknowledgments
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