High Thermoelectric Performance Achieved in Sb-Doped GeTe by Manipulating Carrier Concentration and Nanoscale Twin Grains

Chao Li, Haili Song, Zongbei Dai, Zhenbo Zhao, Chengyan Liu, Hengquan Yang, Chengqiang Cui, Lei Miao

Research output: Contribution to journalArticlepeer-review

Abstract

Lead-free and eco-friendly GeTe shows promising mid-temperature thermoelectric applications. However, a low Seebeck coefficient due to its intrinsically high hole concentration induced by Ge vacancies, and a relatively high thermal conductivity result in inferior thermoelectric performance in pristine GeTe. Extrinsic dopants such as Sb, Bi, and Y could play a crucial role in regulating the hole concentration of GeTe because of their different valence states as cations and high solubility in GeTe. Here we investigate the thermoelectric performance of GeTe upon Sb doping, and demonstrate a high maximum zT value up to 1.88 in Ge0.90 Sb0.10 Te as a result of the significant suppression in thermal conductivity while maintaining a high power factor. The maintained high power factor is due to the markable enhancement in the Seebeck coefficient, which could be attributed to the significant suppression of hole concentration and the valence band convergence upon Sb doping, while the low thermal conductivity stems from the suppression of electronic thermal conductivity due to the increase in electrical resistivity and the lowering of lattice thermal conductivity through strengthening the phonon scattering by lattice distortion, dislocations, and twin boundaries. The excellent thermoelectric performance of Ge0.90 Sb0.10 Te shows good reproducibility and thermal stability. This work confirms that Ge0.90 Sb0.10 Te is a superior thermoelectric material for practical application.

Original languageEnglish
Article number406
JournalMaterials
Volume15
Issue number2
DOIs
Publication statusPublished - 2022 Jan 1

Keywords

  • GeTe
  • Nanoscale twin grains
  • Optimizing carrier concentration
  • Sb-doping

ASJC Scopus subject areas

  • Materials Science(all)
  • Condensed Matter Physics

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