Origin of the high performance in GeTe-based thermoelectric materials upon Bi 2 Te 3 doping

Di Wu, Li Dong Zhao, Shiqiang Hao, Qike Jiang, Fengshan Zheng, Jeff W. Doak, Haijun Wu, Hang Chi, Y. Gelbstein, C. Uher, Christopher M Wolverton, Mercouri Kanatzidis*, Jiaqing He

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

204 Scopus citations

Abstract

As a lead-free material, GeTe has drawn growing attention in thermoelectrics, and a figure of merit (ZT) close to unity was previously obtained via traditional doping/alloying, largely through hole carrier concentration tuning. In this report, we show that a remarkably high ZT of ∼1.9 can be achieved at 773 K in Ge 0.87 Pb 0.13 Te upon the introduction of 3 mol % Bi 2 Te 3 . Bismuth telluride promotes the solubility of PbTe in the GeTe matrix, thus leading to a significantly reduced thermal conductivity. At the same time, it enhances the thermopower by activating a much higher fraction of charge transport from the highly degenerate ∑ valence band, as evidenced by density functional theory calculations. These mechanisms are incorporated and discussed in a three-band (L + ∑ + C) model and are found to explain the experimental results well. Analysis of the detailed microstructure (including rhombohedral twin structures) in Ge 0.87 Pb 0.13 Te + 3 mol % Bi 2 Te 3 was carried out using transmission electron microscopy and crystallographic group theory. The complex microstructure explains the reduced lattice thermal conductivity and electrical conductivity as well.

Original languageEnglish (US)
Pages (from-to)11412-11419
Number of pages8
JournalJournal of the American Chemical Society
Volume136
Issue number32
DOIs
StatePublished - Aug 13 2014

ASJC Scopus subject areas

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

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