Unraveling the Origin of Donor‐Like Effect in Bismuth–Telluride‐Based Thermoelectric Materials
Feng Liu,
Min Zhang,
Pengfei Nan,
Xin Zheng,
Yuzheng Li,
Kang Wu,
Zhongkang Han,
Binghui Ge,
Xinbing Zhao,
Chenguang Fu,
Tiejun Zhu
Affiliations
Feng Liu
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Min Zhang
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Pengfei Nan
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology Anhui University Hefei 230601 China
Xin Zheng
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Yuzheng Li
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Kang Wu
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology Anhui University Hefei 230601 China
Zhongkang Han
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Binghui Ge
Information Materials and Intelligent Sensing Laboratory of Anhui Province, Key Laboratory of Structure and Functional Regulation of Hybrid Materials of Ministry of Education, Institutes of Physical Science and Information Technology Anhui University Hefei 230601 China
Xinbing Zhao
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Chenguang Fu
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
Tiejun Zhu
State Key Laboratory of Silicon and Advanced Semiconductor Materials School of Materials Science and Engineering Zhejiang University Hangzhou 310058 China
The donor‐like effect, depicting the uncontrollable increase of electron density that can significantly alter the thermoelectric performance of both p‐type and n‐type polycrystalline Bi2Te3‐based materials, has long been an intriguing phenomenon, while its origin is still elusive. Herein, it is found that different from the common argument, the donor‐like effect in Bi2Te3‐based polycrystals is a result of the oxygen‐adsorption‐induced evolution of the point defects. The dominant point defect in stoichiometric zone‐melted Bi2Te3 ingot is the acceptor‐like Bi′Te. During the fabrication of high‐strength polycrystals, the exposure of the powders to the air leads to their absorption of oxygen and the formation of secondary phase Bi2TeO5 in the following sintering process. This brings about a change of local chemical equilibrium and promotes the evolution of the intrinsic point defect from acceptor‐like Bi′Te to donor‐like TeBi•. Notably, if the fabrication process is strictly controlled to minimize oxygen adsorption, the evolution of the point defects will be avoided, whereby the donor‐like effect disappears. Consequently, a reproducible high zT value of 1.0 at 325 K can be achieved in Bi2Te2.7Se0.3‐based polycrystals. These results highlight the importance of understanding the evolution of point defects, which is crucial for developing high‐performance Bi2Te3‐based polycrystals and corresponding fabrication processes.
