Point Defect Engineering: Co‐Doping Synergy Realizing Superior Performance in n‐Type Bi<sub>2</sub>Te<sub>3</sub> Thermoelectric Materials
Bin Zhu, Wu Wang, Juan Cui, Jiaqing He
Abstract
Abstract Bi 2 Te 3 has attracted great attention because of its excellent thermoelectric (TE) performance around room temperature. However, the TE property of the n‐type Bi 2 Te 3 is still relatively low compared to the p‐type counterpart, which seriously hinders its commercial application with a combination of the n‐type and p‐type materials. Herein, an effective process of Cl and W co‐doping is employed into the n‐type Bi 2 Te 3 materials to enhance its TE properties. The Bi 1.996 W 0.004 Te 2.476 Cl 0.024 Se 0.5 sample achieves a peak and average ZT over 1.3 and 1.2, respectively, at temperature range of 300–575 K. A 24‐leg TE module of this n‐type material and a home‐made p‐type Bi 2 Te 3 sample can produce a high efficiency over 6% at a temperature gradient of 235 K, which possesses a 71% improvement compared with a commercial Bi 2 Te 3 module. This high performance is ascribed to the effect of the Cl and W doping. This co‐doping not only significantly increases the Grüneisen parameter but also successfully induces interstitial atoms in the van der Waals gap, which lead to a low lattice thermal conductivity (κ l ) of 0.31W m −1 K −1 and a boosted charge transport. This finding represents an important step to promote the development of the n‐type Bi 2 Te 3 materials.