Gradient Nanotwins and Enhanced Weighted Mobility Synergistically Upgrade Bi0.5Sb1.5Te3 Thermoelectric and Mechanical Performance

• Published in: Advanced functional materials Vol. 34; no. 25
• Main Authors: Pang, Kaikai, Miao, Liya, Zhang, Qiang, Pan, Qiaoyan, Liu, Yan, Shi, Huilie, Li, Jingsong, Zhou, Wenjie, Zhang, Zongwei, Zhang, Yuyou, Wu, Gang, Tan, Xiaojian, Noudem, Jacques G., Wu, Jiehua, Sun, Peng, Hu, Haoyang, Liu, Guo‐Qiang, Jiang, Jun
• Format: Journal Article
• Language: English
• Published: Hoboken Wiley Subscription Services, Inc 01-06-2024
• Subjects: Bend strength; Bi0.5Sb1.5Te3; Bismuth tellurides; Carrier transport; Compressive strength; Diamond pyramid hardness; gradient nanotwins; Mechanical properties; Microstructure; Modules; Performance measurement; Thermal conductivity; Thermoelectric materials; thermoelectric modules; weighted mobility
• ISSN: 1616-301X; 1616-3028
• DOI: 10.1002/adfm.202315591

Bi2Te3‐based alloys have historically dominated the commercial realm of near room‐temperature thermoelectric (TE) materials. However, the more widespread application is currently constrained by its mediocre TE performance and inferior mechanical properties resulting from intrinsic hierarchical structure. Herein, microstructure modulation and carrier transport optimization strategies are employed to efficiently balance the electro‐thermal transport performance. Specifically, the weighted mobility increases by 24%, while the lattice thermal conductivity decreases by 31% at 350 K compared to the matrix. Consequently, the Bi0.5Sb1.496Cu0.004Te2.98 sample attains a peak ZT of 1.45 at 350 K and an average ZT of 1.20 (300–500 K). Moreover, intricated microstructure design, exemplified by the gradient twin structure, significantly enhances the mechanical performance metrics, including Vickers hardness, compressive strength, and bending strength, to notable levels of 0.94 GPa, 224 MPa, and 58 MPa, respectively. Consequently, the constructed 17‐pair TE modules demonstrate a maximum conversion efficiency of 6.5% at ΔT = 200 K, surpassing the majority of reported Bi2Te3‐based modules. This study provides novel insights into the synergistic enhancement of TE and mechanical properties in Bi2Te3‐based materials, with potential applicability to other TE systems.
The microstructure modulation by distinctive gradient twin boundaries, along with enhanced weighted mobility, achieve an exceptional balance in electro‐thermal transport. The Bi0.5Sb1.496Cu0.004Te2.98 sample attains a competitive peak ZT of 1.45 and a compressive strength of 224 MPa. Consequently, the constructed 17‐pair thermoelectric modules demonstrate an outstanding conversion efficiency of 6.5% at ΔT = 200 K.