Enhanced Thermoelectric Performance of <i>P</i>‐Type (Bi,Sb)<sub>2</sub>Te<sub>3</sub> by Incorporating Non‐Stoichiometric Ag<sub>5</sub>Te<sub>3</sub> and Refining Te‐Se Ratio
Yuyou Zhang, Kaikai Pang, Qiang Zhang, Yanan Li, Wenjie Zhou, Xiaojian Tan, Jacques Noudem, Gang Wu, Lidong Chen, Haoyang Hu, Peng Sun, Jiehua Wu, Guoqiang Liu, Jun Jiang
Abstract
Abstract Power generation modules utilizing thermoelectric (TE) materials are suitable for recycling widespread low‐grade waste heat (<600 K), highlighting the immediate necessity for advanced Bi 2 Te 3 ‐based alloys. Herein, the substantial enhancement in TE performance of the p ‐type Bi 0.4 Sb 1.6 Te 3 (BST) sintered sample is realized by subtly incorporating the non‐stoichiometric Ag 5 Te 3 and counteractive Se. Specifically, Ag atoms diffused into the BST lattice improve the density‐of‐states effective mass ( m d * ) and boost the hole concentration for the suppressed bipolar effect. The addition of Se further improves m d * prompting the room‐temperature power factor upgrade to 46 W cm −1 K −2 . Concurrently, the lattice thermal conductivity is considerably lowered by multiple scattering sources exemplified by Sb‐rich nanoprecipitates and dense dislocations. These synergistic results yield a high peak ZT of 1.44 at 375 K and an average ZT of 1.28 between 300 and 500 K in the Bi 0.4 Sb 1.6 Te 2.95 Se 0.05 + 0.05 wt.% Ag 5 Te 3 sample. More significantly, when coupled with n ‐type zone‐melted Bi 2 Te 2.7 Se 0.3 , the integrated 17‐pair TE module achieves a competitive conversion efficiency of 6.1% and an output power density of 0.40 W cm −2 at a temperature difference of 200 K, demonstrating great potential for practical applications.