Chemical Insights into PbSe- x%HgSe: High Power Factor and Improved Thermoelectric Performance by Alloying with Discordant Atoms

James M. Hodges, Shiqiang Hao, Jann A. Grovogui, Xiaomi Zhang, Trevor P. Bailey, Xiang Li, Zhehong Gan, Yan Yan Hu, Ctirad Uher, Vinayak P. Dravid, Chris Wolverton, Mercouri G Kanatzidis

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

Thermoelectric generators can convert heat directly into usable electric power but suffer from low efficiencies and high costs, which have hindered wide-scale applications. Accordingly, an important goal in the field of thermoelectricity is to develop new high performance materials that are composed of more earth-abundant elements. The best systems for midtemperature power generation rely on heavily doped PbTe, but the Te in these materials is scarce in the Earth's crust. PbSe is emerging as a less expensive alternative to PbTe, although it displays inferior performance due to a considerably smaller power factor S2σ, where S is the Seebeck coefficient and σ is electrical conductivity. Here, we present a new p-type PbSe system, Pb0.98Na0.02Se-x%HgSe, which yields a very high power factor of ∼20 μW·cm-1·K-2 at 963 K when x = 2, a 15% improvement over the best performing PbSe-x%MSe materials. The enhancement is attributed to a combination of high carrier mobility and the early onset of band convergence in the Hg-alloyed samples (∼550 K), which results in a significant increase in the Seebeck coefficient. Interestingly, we find that the Hg2+ cations sit at an off-centered position within the PbSe lattice, and we dub the displaced Hg atoms "discordant". DFT calculations indicate that this feature plays a role in lowering thermal conductivity, and we believe that this insight may inspire new design criteria for engineering high performance thermoelectric materials. The high power factor combined with a decrease in thermal conductivity gives a high figure of merit ZT of 1.7 at 970 K, the highest value reported for p-type PbSe to date.

Original languageEnglish
JournalJournal of the American Chemical Society
DOIs
Publication statusAccepted/In press - Jan 1 2018

Fingerprint

Alloying
Atoms
Seebeck coefficient
Thermal Conductivity
Thermal conductivity
Earth (planet)
Thermoelectricity
Carrier mobility
Electric Conductivity
Discrete Fourier transforms
Power generation
Positive ions
Cations
Hot Temperature
lead selenide
Costs and Cost Analysis
Costs

ASJC Scopus subject areas

  • Catalysis
  • Chemistry(all)
  • Biochemistry
  • Colloid and Surface Chemistry

Cite this

Chemical Insights into PbSe- x%HgSe : High Power Factor and Improved Thermoelectric Performance by Alloying with Discordant Atoms. / Hodges, James M.; Hao, Shiqiang; Grovogui, Jann A.; Zhang, Xiaomi; Bailey, Trevor P.; Li, Xiang; Gan, Zhehong; Hu, Yan Yan; Uher, Ctirad; Dravid, Vinayak P.; Wolverton, Chris; Kanatzidis, Mercouri G.

In: Journal of the American Chemical Society, 01.01.2018.

Research output: Contribution to journalArticle

Hodges, James M. ; Hao, Shiqiang ; Grovogui, Jann A. ; Zhang, Xiaomi ; Bailey, Trevor P. ; Li, Xiang ; Gan, Zhehong ; Hu, Yan Yan ; Uher, Ctirad ; Dravid, Vinayak P. ; Wolverton, Chris ; Kanatzidis, Mercouri G. / Chemical Insights into PbSe- x%HgSe : High Power Factor and Improved Thermoelectric Performance by Alloying with Discordant Atoms. In: Journal of the American Chemical Society. 2018.
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AU - Zhang, Xiaomi

AU - Bailey, Trevor P.

AU - Li, Xiang

AU - Gan, Zhehong

AU - Hu, Yan Yan

AU - Uher, Ctirad

AU - Dravid, Vinayak P.

AU - Wolverton, Chris

AU - Kanatzidis, Mercouri G

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AB - Thermoelectric generators can convert heat directly into usable electric power but suffer from low efficiencies and high costs, which have hindered wide-scale applications. Accordingly, an important goal in the field of thermoelectricity is to develop new high performance materials that are composed of more earth-abundant elements. The best systems for midtemperature power generation rely on heavily doped PbTe, but the Te in these materials is scarce in the Earth's crust. PbSe is emerging as a less expensive alternative to PbTe, although it displays inferior performance due to a considerably smaller power factor S2σ, where S is the Seebeck coefficient and σ is electrical conductivity. Here, we present a new p-type PbSe system, Pb0.98Na0.02Se-x%HgSe, which yields a very high power factor of ∼20 μW·cm-1·K-2 at 963 K when x = 2, a 15% improvement over the best performing PbSe-x%MSe materials. The enhancement is attributed to a combination of high carrier mobility and the early onset of band convergence in the Hg-alloyed samples (∼550 K), which results in a significant increase in the Seebeck coefficient. Interestingly, we find that the Hg2+ cations sit at an off-centered position within the PbSe lattice, and we dub the displaced Hg atoms "discordant". DFT calculations indicate that this feature plays a role in lowering thermal conductivity, and we believe that this insight may inspire new design criteria for engineering high performance thermoelectric materials. The high power factor combined with a decrease in thermal conductivity gives a high figure of merit ZT of 1.7 at 970 K, the highest value reported for p-type PbSe to date.

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