High Thermoelectric Performance in Chalcopyrite Cu1- xAgxGaTe2-ZnTe: Nontrivial Band Structure and Dynamic Doping Effect

Hongyao Xie, Yukun Liu, Yinying Zhang, Shiqiang Hao, Zhi Li, Matthew Cheng, Songting Cai, G. Jeffrey Snyder, Christopher Wolverton, Ctirad Uher, Vinayak P. Dravid, Mercouri G. Kanatzidis*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

1 Scopus citations

Abstract

The understanding of thermoelectric properties of ternary I-III-VI2type (I = Cu, Ag; III = Ga, In; and VI = Te) chalcopyrites is less well developed. Although their thermal transport properties are relatively well studied, the relationship between the electronic band structure and charge transport properties of chalcopyrites has been rarely discussed. In this study, we reveal the unusual electronic band structure and the dynamic doping effect that could underpin the promising thermoelectric properties of Cu1-xAgxGaTe2compounds. Density functional theory (DFT) calculations and electronic transport measurements suggest that the Cu1-xAgxGaTe2compounds possess an unusual non-parabolic band structure, which is important for obtaining a high Seebeck coefficient. Moreover, a mid-gap impurity level was also observed in Cu1-xAgxGaTe2, which leads to a strong temperature-dependent carrier concentration and is able to regulate the carrier density at the optimized value for a wide temperature region and thus is beneficial to obtaining the high power factor and high average ZT of Cu1-xAgxGaTe2compounds. We also demonstrate a great improvement in the thermoelectric performance of Cu1-xAgxGaTe2by introducing Cu vacancies and ZnTe alloying. The Cu vacancies are effective in increasing the hole density and the electrical conductivity, while ZnTe alloying reduces the thermal conductivity. As a result, a maximum ZT of 1.43 at 850 K and a record-high average ZT of 0.81 for the Cu0.68Ag0.3GaTe2-0.5%ZnTe compound are achieved.

Original languageEnglish (US)
Pages (from-to)9113-9125
Number of pages13
JournalJournal of the American Chemical Society
Volume144
Issue number20
DOIs
StatePublished - May 25 2022

ASJC Scopus subject areas

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

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