Origin of the high performance in GeTe-based thermoelectric materials upon Bi2Te3 doping

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

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179 Citations (Scopus)

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 Ge0.87Pb0.13Te upon the introduction of 3 mol % Bi2Te3. 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 Ge0.87Pb0.13Te + 3 mol % Bi2Te3 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
Pages (from-to)11412-11419
Number of pages8
JournalJournal of the American Chemical Society
Volume136
Issue number32
DOIs
Publication statusPublished - Aug 13 2014

ASJC Scopus subject areas

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

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    Wu, D., Zhao, L. D., Hao, S., Jiang, Q., Zheng, F., Doak, J. W., Wu, H., Chi, H., Gelbstein, Y., Uher, C., Wolverton, C., Kanatzidis, M., & He, J. (2014). Origin of the high performance in GeTe-based thermoelectric materials upon Bi2Te3 doping. Journal of the American Chemical Society, 136(32), 11412-11419. https://doi.org/10.1021/ja504896a