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High near-room temperature figure of merit of n-type Bi2GeTe4-based thermoelectric materials via a stepwise optimization of carrier concentration.

Authors :
Yin, Liang-Cao
Liu, Wei-Di
Shi, Xiao-Lei
Gao, Han
Li, Meng
Wang, De-Zhuang
Wu, Hao
Kou, Liangzhi
Guo, Haizhong
Wang, Yifeng
Liu, Qingfeng
Chen, Zhi-Gang
Source :
Chemical Engineering Journal. Apr2022:Part 3, Vol. 433, pN.PAG-N.PAG. 1p.
Publication Year :
2022

Abstract

• Stepwise carrier concentration optimization of Bi 2 GeTe 4 thermoelectric materials. • Ge vacancy-engineering transfer Bi 2 GeTe 4 into highly degenerated semiconductor. • Carrier concentration optimization leads to high power factor of 4.2 μW cm−1 K−2. • Approaching a record-high zT value of ∼ 0.22 at 423 K in Bi 2 Ge 1.45 Te 4. Bi 2 GeTe 4 is a promising near room-temperature thermoelectric candidate with a low lattice thermal conductivity. Carrier concentration of intrinsic Bi 2 GeTe 4 changes dramatically with tiny Ge content adjustment, leading to a challenge in carrier concentration optimization. To overcome this challenge, we firstly introduce excessive Ge into Bi 2 GeTe 4 to shift the Fermi level deep into the conduction band and transfer Bi 2 GeTe 4 into a highly degenerate n-type semiconductor. Secondly, the embedded p-type Bi 2 Ge 2 Te 5 secondary phase induces further optimization of the Fermi level and carrier concentration. Finally, the power factor of the as-synthesized Bi 2 GeTe 4 -based material is significantly increased from ∼ 0.08 μW cm−1 K−2 to ∼ 4.2 μW cm−1 K−2 at 423 K when increasing the nominal Ge content (x) of Bi 2 Ge x Te 4 from 1 to 1.45. Correspondingly, a high figure-of-merit of ∼ 0.22 at 423 K is achieved in Bi 2 GeTe 4 -based thermoelectric materials. This result indicates our viable stepwise strategy can be used to optimize carrier concentration and achieve high thermoelectric performance of the n-type Bi 2 GeTe 4. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
13858947
Volume :
433
Database :
Academic Search Index
Journal :
Chemical Engineering Journal
Publication Type :
Academic Journal
Accession number :
155102465
Full Text :
https://doi.org/10.1016/j.cej.2021.133775