Title: High Thermoelectric Performance in Chalcopyrite Cu_1-xAg_xGaTe₂–ZnTe: Nontrivial Band Structure and Dynamic Doping Effect

Abstract

The understanding of thermoelectric properties of ternary I–III–VI₂ type (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 Cu_1–xAg_xGaTe₂ compounds. Density functional theory (DFT) calculations and electronic transport measurements suggest that the Cu_1–xAg_xGaTe₂ compounds 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 Cu_1–xAg_xGaTe₂, 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 Cu_1–xAg_xGaTe₂ compounds. We also demonstrate a great improvement in the thermoelectric performance of Cu_1–xAg_xGaTe₂ by 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 amore » result, a maximum ZT of 1.43 at 850 K and a record-high average ZT of 0.81 for the Cu_0.68Ag_0.3GaTe₂–0.5%ZnTe compound are achieved.« less

Authors:

Xie, Hongyao  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-2472-3866"

Liu, Yukun ^[1]; Zhang, Yinying  ^[2];

• Search DOE PAGES for author "Zhang, Yinying"
• Search DOE PAGES for ORCID "0000-0001-9696-1348"

Hao, Shiqiang  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-7985-4468"

Li, Zhi  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-0451-567X"

Cheng, Matthew  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-1062-5974"

Cai, Songting  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2203-5362"

Snyder, G. Jeffrey  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-1414-8682"

Wolverton, Christopher  ^[1];

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• Search DOE PAGES for ORCID "0000-0003-2248-474X"

Uher, Ctirad ^[2]; Dravid, Vinayak P.  ^[1];

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• Search DOE PAGES for ORCID "0000-0002-6007-3063"

Kanatzidis, Mercouri G.  ^[1]

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• Search DOE PAGES for ORCID "0000-0003-2037-4168"

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+ Show Author Affiliations

1. Northwestern Univ., Evanston, IL (United States)
2. Univ. of Michigan, Ann Arbor, MI (United States)

Publication Date:

Tue May 10 00:00:00 EDT 2022

Research Org.:

Northwestern Univ., Evanston, IL (United States)

Sponsoring Org.:

USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF)

OSTI Identifier:

1867601

Grant/Contract Number:  

SC0014520; ECCS-2025633; DMR-1720139

Resource Type:

Accepted Manuscript

Journal Name:

Journal of the American Chemical Society

Additional Journal Information:

Journal Volume: 144; Journal Issue: 20; Journal ID: ISSN 0002-7863

Publisher:

American Chemical Society (ACS)

Country of Publication:

United States

Language:

English

Subject:

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; chalcopyrite; nontrivial band structure; dynamic doping effect; Cu vacancy,; ZnTe alloying