Versatile vanadium doping induces high thermoelectric performance in GeTe via band alignment and structural modulation

Sun, Qiang and Li, Meng and Shi, Xiao-Lei ORCID: https://orcid.org/0000-0003-0905-2547 and Xu, Sheng-Duo and Liu, Wei-Di and Hong, Min and Lyu, Wan‐yu and Yin, Yu and Dargusch, Matthew and Zou, Jin and Chen, Zhi-Gang ORCID: https://orcid.org/0000-0002-9309-7993 (2021) Versatile vanadium doping induces high thermoelectric performance in GeTe via band alignment and structural modulation. Advanced Energy Materials:2100544. pp. 1-9. ISSN 1614-6832


Abstract

Owing to the moderate energy offset between light and heavy band edges of the rock‐salt structured GeTe, its figure‐of‐merit (ZT) can be enhanced by the rational manipulation of electronic band structures. In this study, density functional theory calculations are implemented to predict that V is an effective dopant for GeTe to enlarge the bandgap and converge the energy offset, which suppresses the bipolar conduction and increases the effective mass. Experimentally, V‐doped Ge1−xVxTe samples are demonstrated to have an enhanced Seebeck coefficient from ≈163 to ≈191 µV K−1. Extra alloying with Bi in Ge1−x−yVxBiyTe can optimize the carrier concentration to further enhance the Seebeck coefficient up to ≈252 µV K−1, plus an outstanding power factor of ≈43 µW cm−1 K−2. Comprehensive structural characterization results also verify the refinement of grain size by V‐doping, associated with highly dense grain boundaries, stacking faults, nanoprecipitates, and point defects, reinforcing the wide‐frequency phonon scattering and in turn, securing an ultralow thermal conductivity of ≈0.59 W m−1 K−1. As a result, the Ge0.9V0.02Bi0.08Te sample shows a peak ZT of >2.1 at 773 K, with an average plateaued average ZT of >2.0 from 623 and 773 K, which extends better thermoelectric behavior for GeTe over a wider temperature range. This study clarifies the multiple benefits of V‐doping in GeTe‐based derivatives and provides a framework for a new‐type of high‐performance middle‐temperature thermoelectric material.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Permanent restricted access to ArticleFirst version, in accordance with the copyright policy of the publisher.
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Faculty/School / Institute/Centre: Current - Institute for Advanced Engineering and Space Sciences - Centre for Future Materials (1 Jan 2017 -)
Date Deposited: 23 Apr 2021 00:40
Last Modified: 27 Sep 2021 03:51
Uncontrolled Keywords: band structure, GeTe, structural manipulation, thermoelectrics, Vanadium
Fields of Research (2008): 09 Engineering > 0912 Materials Engineering > 091205 Functional Materials
Fields of Research (2020): 40 ENGINEERING > 4016 Materials engineering > 401605 Functional materials
Identification Number or DOI: https://doi.org/10.1002/aenm.202100544
URI: http://eprints.usq.edu.au/id/eprint/41856

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