High Thermoelectric Performance in SnTe-AgSbTe2 Alloys from Lattice Softening, Giant Phonon-Vacancy Scattering, and Valence Band Convergence

Gangjian Tan, Shiqiang Hao, Riley C. Hanus, Xiaomi Zhang, Shashwat Anand, Trevor P. Bailey, Alexander J.E. Rettie, Xianli Su, Ctirad Uher, Vinayak P. Dravid, G. Jeffrey Snyder, Chris Wolverton, Mercouri G. Kanatzidis

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Abstract

We report on the underlying mechanism that enables the SnTe-AgSbTe2 system to exhibit superior thermoelectric figure of merit (ZT) compared to its parent compound SnTe. We show that AgSbTe2 alloying has a profound impact on the band structure of SnTe by converging the energies of its light and heavy valence bands, leading to significantly enhanced Seebeck coefficients. We have also unraveled a significant connection between alloying and defect stability in this system, wherein the Sn vacancy concentration increases significantly when Ag and Sb are alloyed on the Sn site. The increased Sn vacancy concentration dramatically reduces the lattice thermal conductivity through both lattice softening and phonon-vacancy scattering to ∼0.4 W m-1 K-1 at 800 K. Consequently, a ZT value of 1.2 at 800 K for AgSn5SbTe7 can be achieved by doping I on Te sites. This represents a 300% improvement over pristine SnTe, outperforming many reported SnTe-based thermoelectric materials.

Original languageEnglish
Pages (from-to)705-712
Number of pages8
JournalACS Energy Letters
Volume3
Issue number3
DOIs
Publication statusPublished - Mar 9 2018

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ASJC Scopus subject areas

  • Chemistry (miscellaneous)
  • Renewable Energy, Sustainability and the Environment
  • Fuel Technology
  • Energy Engineering and Power Technology
  • Materials Chemistry

Cite this

Tan, G., Hao, S., Hanus, R. C., Zhang, X., Anand, S., Bailey, T. P., Rettie, A. J. E., Su, X., Uher, C., Dravid, V. P., Snyder, G. J., Wolverton, C., & Kanatzidis, M. G. (2018). High Thermoelectric Performance in SnTe-AgSbTe2 Alloys from Lattice Softening, Giant Phonon-Vacancy Scattering, and Valence Band Convergence. ACS Energy Letters, 3(3), 705-712. https://doi.org/10.1021/acsenergylett.8b00137