High Thermoelectric Performance Achieved in Sb-Doped GeTe by Manipulating Carrier Concentration and Nanoscale Twin Grains

Chao Li; Haili Song; Zongbei Dai; Zhenbo Zhao; Chengyan Liu; Hengquan Yang; Chengqiang Cui; Lei Miao

doi:10.3390/ma15020406

High Thermoelectric Performance Achieved in Sb-Doped GeTe by Manipulating Carrier Concentration and Nanoscale Twin Grains

Materials (Basel). 2022 Jan 6;15(2):406. doi: 10.3390/ma15020406.

Authors

Chao Li^{1

2

3}, Haili Song⁴, Zongbei Dai³, Zhenbo Zhao³, Chengyan Liu⁵, Hengquan Yang⁶, Chengqiang Cui^{1

2}, Lei Miao^{5

7}

Affiliations

¹ School of Electromechanical Engineering, Guangdong University of Technology, Guangzhou 510006, China.
² Ji Hua Laboratory, Foshan 528299, China.
³ The Fifth Electronics Research Institute of Ministry of Industry and Information Technology, Guangzhou 510006, China.
⁴ Key Laboratory of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen University, Guangzhou 510275, China.
⁵ Guangxi Key Laboratory of Information Material, Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004, China.
⁶ Jiangsu Key Laboratory of Modern Measurement Technology and Intelligent Systems, School of Physics and Electronic & Electrical Engineering, Huaiyin Normal University, Huai'an 223300, China.
⁷ SIT Research Laboratories, Innovative Global Program, Department of Materials Science and Engineering, Faculty of Engineering, Shibaura Institute of Technology, Tokyo 135-8548, Japan.

Abstract

Lead-free and eco-friendly GeTe shows promising mid-temperature thermoelectric applications. However, a low Seebeck coefficient due to its intrinsically high hole concentration induced by Ge vacancies, and a relatively high thermal conductivity result in inferior thermoelectric performance in pristine GeTe. Extrinsic dopants such as Sb, Bi, and Y could play a crucial role in regulating the hole concentration of GeTe because of their different valence states as cations and high solubility in GeTe. Here we investigate the thermoelectric performance of GeTe upon Sb doping, and demonstrate a high maximum zT value up to 1.88 in Ge_0.90Sb_0.10Te as a result of the significant suppression in thermal conductivity while maintaining a high power factor. The maintained high power factor is due to the markable enhancement in the Seebeck coefficient, which could be attributed to the significant suppression of hole concentration and the valence band convergence upon Sb doping, while the low thermal conductivity stems from the suppression of electronic thermal conductivity due to the increase in electrical resistivity and the lowering of lattice thermal conductivity through strengthening the phonon scattering by lattice distortion, dislocations, and twin boundaries. The excellent thermoelectric performance of Ge_0.90Sb_0.10Te shows good reproducibility and thermal stability. This work confirms that Ge_0.90Sb_0.10Te is a superior thermoelectric material for practical application.

Keywords: GeTe; Sb-doping; nanoscale twin grains; optimizing carrier concentration.

Abstract

Grants and funding