Unraveling electronic origins for boosting thermoelectric performance of p-type (Bi,Sb)2Te3

• Published in: Science advances 2024-05, Vol.10 (21), p.eadn9959-eadn9959
• Main Authors: Cheng, Rui, Ge, Haoran, Huang, Shengpu, Xie, Sen, Tong, Qiwei, Sang, Hao, Yan, Fan, Zhu, Liangyu, Wang, Rui, Liu, Yong, Hong, Min, Uher, Ctirad, Zhang, Qingjie, Liu, Wei, Tang, Xinfeng
• Format: Article
• Language: English
• ISSN: 2375-2548
• DOI: 10.1126/sciadv.adn9959

P-type Bi2-xSbxTe3 compounds are crucial for thermoelectric applications at room temperature, with Bi0.5Sb1.5Te3 demonstrating superior performance, attributed to its maximum density-of-states effective mass (m*). However, the underlying electronic origin remains obscure, impeding further performance optimization. Herein, we synthesized high-quality Bi2-xSbxTe3 (00 l) films and performed comprehensive angle-resolved photoemission spectroscopy (ARPES) measurements and band structure calculations to shed light on the electronic structures. ARPES results directly evidenced that the band convergence along the [Formula: see text]-[Formula: see text] direction contributes to the maximum m* of Bi0.5Sb1.5Te3. Moreover, strategic manipulation of intrinsic defects optimized the hole density of Bi0.5Sb1.5Te3, allowing the extra valence band along [Formula: see text]-[Formula: see text] to contribute to the electrical transport. The synergy of the above two aspects documented the electronic origins of the Bi0.5Sb1.5Te3's superior performance that resulted in an extraordinary power factor of ~5.5 milliwatts per meter per square kelvin. The study offers valuable guidance for further performance optimization of p-type Bi2-xSbxTe3.