High near-room temperature figure of merit of n-type Bi2GeTe4-based thermoelectric materials via a stepwise optimization of carrier concentration
| Autor: | Zhi-Gang Chen, Qingfeng Liu, Han Gao, Meng Li, Haizhong Guo, Yifeng Wang, Hao Wu, Xiaolei Shi, De-Zhuang Wang, Wei-Di Liu, Liangzhi Kou, Liang-Cao Yin |
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| Rok vydání: | 2022 |
| Předmět: |
Materials science
business.industry General Chemical Engineering Degenerate energy levels Fermi level General Chemistry Power factor Thermoelectric materials Industrial and Manufacturing Engineering Lattice thermal conductivity symbols.namesake Semiconductor Thermoelectric effect symbols Environmental Chemistry Figure of merit Optoelectronics business |
| Zdroj: | Chemical Engineering Journal. 433:133775 |
| ISSN: | 1385-8947 |
| Popis: | Bi2GeTe4 is a promising near room-temperature thermoelectric candidate with a low lattice thermal conductivity. Carrier concentration of intrinsic Bi2GeTe4 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 Bi2GeTe4 to shift the Fermi level deep into the conduction band and transfer Bi2GeTe4 into a highly degenerate n-type semiconductor. Secondly, the embedded p-type Bi2Ge2Te5 secondary phase induces further optimization of the Fermi level and carrier concentration. Finally, the power factor of the as-synthesized Bi2GeTe4-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 Bi2GexTe4 from 1 to 1.45. Correspondingly, a high figure-of-merit of ∼0.22 at 423 K is achieved in Bi2GeTe4-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 Bi2GeTe4. |
| Databáze: | OpenAIRE |
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