Abstract
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.
Original language | English |
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Article number | 133775 |
Journal | Chemical Engineering Journal |
Volume | 433 |
DOIs | |
State | Published - 1 Apr 2022 |
Keywords
- BiGeTe
- Carrier concentration
- Optimization
- Thermoelectric
- zT