Arrays of planar vacancies in superior thermoelectric Ge1−x−yCdxBiyTe with band convergence
Article
Article Title | Arrays of planar vacancies in superior thermoelectric Ge1−x−yCdxBiyTe with band convergence |
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ERA Journal ID | 200105 |
Article Category | Article |
Authors | Hong, Min (Author), Wang, Yuan (Author), Liu, Weidi (Author), Matsumura, Syo (Author), Wang, Hao (Author), Zou, Jin (Author) and Chen, Zhi-Gang (Author) |
Journal Title | Advanced Energy Materials |
Journal Citation | 8 (30), pp. 1-10 |
Article Number | 1801837 |
Number of Pages | 10 |
Year | 2018 |
Publisher | John Wiley & Sons |
Place of Publication | Germany |
ISSN | 1614-6832 |
1614-6840 | |
Digital Object Identifier (DOI) | https://doi.org/10.1002/aenm.201801837 |
Web Address (URL) | https://onlinelibrary.wiley.com/doi/10.1002/aenm.201801837 |
Abstract | The multivalence bands in GeTe provide an additional handle to manipulate the thermoelectric performance. Herein, the density‐functional‐theory calculation indicates that Cd doping enables the convergence of these multivalence bands. Plus, the additional Bi dopant serving as the electron donors optimizes the carrier concentration, leading to an enhanced power‐factor in Ge1−x−yCdxBiyTe. Moreover, comprehensive electron microscopy characterizations demonstrate the array of high‐density planar vacancies in Ge1−x−yCdxBiyTe stemming from the absence of {111} Ge atomic planes, which is driven by the reduced formation energy in the scenario of Cd/Bi codoping. Simulations of phonon transport confirm the significant role of planar vacancies in scattering mid‐frequency phonons. Such high‐density planar vacancies, in tandem with grain boundaries and point defects, lead to a lattice thermal conductivity of 0.4 W m−1 K−1 in Ge1−x−yCdxBiyTe, reaching the amorphous limit. Ultimately, a peak zT of 2.2 is realized, which promotes GeTe into the first echelon of cutting‐edge thermoelectric materials. The strategy of combining band convergence and planar vacancies opens an avenue to develop Pb‐free derivatives with superhigh thermoelectric efficiency. |
Keywords | band convergence, GeTe alloys, high-performance thermoelectrics, planar vacancies, TEM characterizations |
ANZSRC Field of Research 2020 | 401605. Functional materials |
Public Notes | File reproduced in accordance with the copyright policy of the publisher/author. |
Byline Affiliations | Centre for Future Materials |
University of Queensland | |
Kyushu University, Japan | |
Institution of Origin | University of Southern Queensland |
Funding source | Australian Research Council (ARC) |
https://research.usq.edu.au/item/q5071/arrays-of-planar-vacancies-in-superior-thermoelectric-ge1-x-ycdxbiyte-with-band-convergence
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