High carrier mobility and high figure of merit in the CuBiSe2 alloyed GeTe

Yin, Liang-Cao and Liu, Wei-Di and Li, Meng and Sun, Qiang and Gao, Han and Wang, De-Zhuang and Wu, Hao and Wang, Yi-Feng and Shi, Xiao-Lei ORCID: https://orcid.org/0000-0003-0905-2547 and Liu, Qingfeng and Chen, Zhi-Gang ORCID: https://orcid.org/0000-0002-9309-7993 (2021) High carrier mobility and high figure of merit in the CuBiSe2 alloyed GeTe. Advanced Energy Materials, 11 (45):2102913. pp. 1-8. ISSN 1614-6832


Abstract

According to the Mott's relation, the figure-of-merit of a thermoelectric material depends on the charge carrier concentration and carrier mobility. This explains the observation that low thermoelectric properties of GeTe-based materials suffer from the degraded carrier mobility, on account of the fluctuation of electronegativity and ionicity of various elements. Here, high-performance CuBiSe2 alloyed GeTe with high carrier mobility due to the small electronegativity difference between Cu and Ge atoms and the weak ionicity of Cu-Te and Bi-Te bonds, is developed. Density functional theory calculations indicate that CuBiSe2 alloying increases the formation energy of Ge vacancies and correspondingly reduces the amount of Ge vacancies, leading to an optimized carrier concentration and a high power factor of ≈37.4 µW cm−1 K−2 at 723 K. Moreover, CuBiSe2 alloying induces dense point defects and triggers ubiquitous lattice distortions, leading to a reduced lattice thermal conductivity of 0.39 W m−1 K−1 at 723 K. These synergistic effects result in an optimization of the carrier mobility, the carrier concentration, and the lattice thermal conductivity, which favors an enhanced peak figure-of-merit of ≈2.2 at 723 K in (GeTe)0.94(CuBiSe2)0.06. This study provides guidance for the screening of GeTe-based thermoelectric materials with high carrier mobility.


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Item Type: Article (Commonwealth Reporting Category C)
Refereed: Yes
Item Status: Live Archive
Additional Information: Files associated with this item cannot be displayed due to copyright restrictions.
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: 28 Oct 2021 01:43
Last Modified: 14 Jun 2022 04:16
Uncontrolled Keywords: carrier mobility; figure-of-merit; GeTe; thermoelectrics
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.202102913
URI: http://eprints.usq.edu.au/id/eprint/43983

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