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Abstract Bandstructure engineering is a key route for thermoelectric performance enhancement. Here, 20–50% Seebeck (S) enhancement is reported for XNiCuySn half‐Heusler samples based onX= Ti. This novel electronic effect is attributed to the emergence of impurity bands of finite extent, due to the Cu dopants. Depending on the dispersion, extent, and offset with respect to the parent material, these bands are shown to enhanceSto different degrees. Experimentally, this effect is controllable by the Ti content of the samples, with the addition of Zr/Hf gradually removing the enhancement. At the same time, the mobility remains largely intact, enabling power factors ≥3 mW m−1K−2near room temperature, increasing to ≥5 mW m−1K−2at high temperature. Combined with reduced thermal conductivity due to the Cu interstitials, this enables high averagezT= 0.67–0.72 between 320 and 793 K for XNiCuySn compositions with ≥70% Ti. This work reveals the existence of a new route for electronic performance enhancement in n‐type XNiSn materials that are normally limited by their single carrier pocket. In principle, impurity bands can be applied to other materials and provide a new direction for further development.
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Large enhancement of thermoelectric effects in multiple quantum dots in a serial configuration due to Coulomb interactions
Abstract In the present work we theoretically study Seebeck effect in a set of several quantum dots in a serial configuration coupled to nonmagnetic conducting electrodes. We focus on the combined effect of intra-dot Coulomb interactions between electrons and the number of dots on the thermopower ( S ) and the thermoelectric figure of merit (ZT) of the considered transport junction within the Coulomb blockade regime. We show that a strong enhancement of the both S and ZT may occur when the chemical potential of electrodes is situated within the Coulomb gap in the electron transmission spectrum thus indicating a possibility of significant increase of the efficiency of heat-to-electric energy conversion. The enhancement becomes more pronounced when the number of dots increases.
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- Award ID(s):
- 2122102
- PAR ID:
- 10326340
- Date Published:
- Journal Name:
- Journal of Physics: Condensed Matter
- Volume:
- 34
- Issue:
- 25
- ISSN:
- 0953-8984
- Page Range / eLocation ID:
- 255302
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1088/1361-648X/ac640c
