Regulating Te Vacancies through Dopant Balancing via Excess Ag Enables Rebounding Power Factor and High Thermoelectric Performance in p-Type PbTe

Hanhwi Jang, Jong Ho Park, Ho Seong Lee, Byungki Ryu, Su Dong Park, Hyeon Ah Ju, Sang Hyeok Yang, Young Min Kim, Woo Hyun Nam, Heng Wang, James Male, Gerald Jeffrey Snyder, Minjoon Kim, Yeon Sik Jung*, Min Wook Oh

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Thermoelectric properties are frequently manipulated by introducing point defects into a matrix. However, these properties often change in unfavorable directions owing to the spontaneous formation of vacancies at high temperatures. Although it is crucial to maintain high thermoelectric performance over a broad temperature range, the suppression of vacancies is challenging since their formation is thermodynamically preferred. In this study, using PbTe as a model system, it is demonstrated that a high thermoelectric dimensionless figure of merit, zT ≈ 2.1 at 723 K, can be achieved by suppressing the vacancy formation via dopant balancing. Hole-killer Te vacancies are suppressed by Ag doping because of the increased electron chemical potential. As a result, the re-dissolution of Na2Te above 623 K can significantly increase the hole concentration and suppress the drop in the power factor. Furthermore, point defect scattering in material systems significantly reduces lattice thermal conductivity. The synergy between defect and carrier engineering offers a pathway for achieving a high thermoelectric performance by alleviating the power factor drop and can be utilized to enhance thermoelectric properties of thermoelectric materials.

Original languageEnglish (US)
JournalAdvanced Science
DOIs
StateAccepted/In press - 2021

Keywords

  • defect engineering
  • power factor
  • re-dissolution
  • thermal conductivity
  • thermoelectrics

ASJC Scopus subject areas

  • Medicine (miscellaneous)
  • Chemical Engineering(all)
  • Materials Science(all)
  • Biochemistry, Genetics and Molecular Biology (miscellaneous)
  • Engineering(all)
  • Physics and Astronomy(all)

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