Modulation of Vacancy Defects and Texture for High Performance n‐Type Bi<sub>2</sub>Te<sub>3</sub> via High Energy Refinement
Jing Zhou, Jianghe Feng, Hao Li, Duo Liu, Guojuan Qiu, Feng Qiu, Juan Li, Zhong‐Zhen Luo, Zhigang Zou, Rong Sun, Ruiheng Liu
Abstract
Abstract The carrier concentration in n‐type layered Bi 2 Te 3 ‐based thermoelectric (TE) material is significantly impacted by the donor‐like effect, which would be further intensified by the nonbasal slip during grain refinement of crushing, milling, and deformation, inducing a big challenge to improve its TE performance and mechanical property simultaneously. In this work, high‐energy refinement and hot‐pressing are used to stabilize the carrier concentration due to the facilitated recovery of cation and anion vacancies. Based on this, combined with SbI 3 doping and hot deformation, the optimized carrier concentration and high texture degree are simultaneously realized. As a result, a peak figure of merit ( zT ) of 1.14 at 323 K for Bi 2 Te 2.7 Se 0.3 + 0.05 wt.% SbI 3 sample with the high bending strength of 100 Mpa is obtained. Furthermore, a 31‐couple thermoelectric cooling device consisted of n‐type Bi 2 Te 2.7 Se 0.3 + 0.05 wt.% SbI 3 and commercial p‐type Bi 0.5 Sb 1.5 Te 3 legs is fabricated, which generates the large maximum temperature difference (Δ T max ) of 85 K at a hot‐side temperature of 343 K. Thus, the discovery of recovery effect in high energy refinement and hot‐pressing has significant implications for improving TE performance and mechanical strength of n‐type Bi 2 Te 3 , thereby promoting its applications in harsh conditions.