Abstract
Owing to the diversity of composition and excellent transport properties, the ternary I-III-VI2 type diamond-like chalcopyrite compounds are attractive functional semiconductors, including as thermoelectric materials. In this family, CuInTe2 and CuGaTe2 are well investigated and achieve maximum ZT values of ∼1.4 at 950 K and an average ZT of 0.43. However, both compounds have poor electrical conductivity at low temperature, resulting in low ZT below 450 K. In this work, we have greatly improved the thermoelectric performance in the quinary diamondoid compound (Cu0.8Ag0.2)(In0.2Ga0.8)Te2 by understanding and controlling the effects of different constituent elements on the thermoelectric transport properties. Our combined theoretical and experimental effort indicates that Ga in the In site of the lattice decreases the carrier effective mass and improves the electrical conductivity and power factor of Cu0.8Ag0.2In1-xGaxTe2. Furthermore, Ag in the Cu site strongly suppresses the heat transport via the enhanced acoustic phonon-optical phonon coupling effects, leading to the ultralow thermal conductivity of ∼0.49 W m-1 K-1 at 850 K in Cu0.8Ag0.2In0.2Ga0.8Te2. Defect formation energy calculations suggest intrinsic Cu vacancies introduce defect levels that are important to the temperature-dependent hole density and electrical conductivity. Therefore, we introduced extra Cu vacancies to optimize the hole carrier density and improve the power factor of Cu0.8Ag0.2In0.2Ga0.8Te2. As a result, a maximum ZT of ∼1.5 at 850 K and an average ZT of 0.78 in the temperature range of 400-850 K are obtained, which is among the highest in the diamond-like compound family.
Original language | English (US) |
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Pages (from-to) | 5978-5989 |
Number of pages | 12 |
Journal | Journal of the American Chemical Society |
Volume | 143 |
Issue number | 15 |
DOIs | |
State | Published - Apr 21 2021 |
Funding
This work was primarily supported by a grant from the U.S. Department of Energy, Office of Science, and Office of Basic Energy Sciences under Award DE-SC0014520. This work also made use of the EPIC facility of Northwestern University’s NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (Grant ECCS 2025633); the MRSEC program (Grant NSF DMR-1720139) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. User Facilities are supported by the Office of Science of the U.S. Department of Energy under Contracts DE-AC02-06CH11357 and DE-AC02-05CH11231.
ASJC Scopus subject areas
- Catalysis
- General Chemistry
- Biochemistry
- Colloid and Surface Chemistry