Enhancing thermoelectric performance of GeSb4Te7 single crystals through synergistic band and point defect engineering

Enhancing thermoelectric performance of GeSb4Te7 single crystals through synergistic band and point defect engineering

GeSb4Te7, a quasi-two-dimensional semiconductor, exhibits high potential in thermoelectric applications. Herein, efficacious Yb/In co-doping has been realized in the GeSb4Te7 single crystals prepared by the slow-cooling method to enhance their thermoelectric properties. DFT calculations demonstrate...

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Bibliographic Details
Main Authors: Peng Chen, Chun Yan, Yanci Yan, Hong Wu, Guang Han, Denghang Li, Wei Dong, Bin Zhang, Xu Lu, Dengfeng Li, Yun Zhou, Xiaoyuan Zhou, Guoyu Wang
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Journal of Materiomics
Subjects:
Thermoelectric
GeSb4Te7 single crystal
Band engineering
Point defect engineering
Intrinsically low lattice thermal conductivity
Online Access:http://www.sciencedirect.com/science/article/pii/S2352847825000371
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Summary:GeSb4Te7, a quasi-two-dimensional semiconductor, exhibits high potential in thermoelectric applications. Herein, efficacious Yb/In co-doping has been realized in the GeSb4Te7 single crystals prepared by the slow-cooling method to enhance their thermoelectric properties. DFT calculations demonstrate that the inherently low lattice thermal conductivity of GeSb4Te7 is associated with its low phonon group velocities and strong lattice anharmonicity. Yb doping at Ge sites significantly lowers the lattice thermal conductivity, primarily by promoting phonon scattering from point defects. Furthermore, In doping creates an impurity band, leading to a distortion in the density of states (DOS) near the Fermi level and contributing to enhanced Seebeck coefficient. Benefiting from enhanced electrical properties and decreased thermal conductivity, the zT of Yb/In co-doped samples is markedly improved: Ge0.95Yb0.02In0.03Sb4Te7 single-crystal sample obtains a record peak zT (0.81) at 673 K and maintains an average zT (0.55) between 323 K and 773 K, signifying a rise of 62% and 83%, respectively, compared with the pristine GeSb4Te7. This study proposes a novel strategy to boost the thermoelectric properties of layered-structured GeSb4Te7 compounds.
ISSN:2352-8478

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