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Anomalous Thermoelectric Performance in Asymmetric Dirac Semimetal BaAgBi
Zhou, Zizhen1; Peng, Kunling2,3; Xiao, Shijuan1; Wei, Yiqing1; Dai, Qinjin1; Lu, Xu1; Wang, Guoyu4; Zhou, Xiaoyuan1
2022-03-17
摘要Multiple-band degeneracy has been widely recognized to be beneficial for high thermoelectric performance. Here, we discover that the p-type Dirac bands with lower degeneracy synergistically produce a higher Seebeck coefficient and electrical conductivity in topological semimetal BaAgBi. The anomalous transport phenomenon intrinsically originated from the asymmetric electronic structures: (i) complete p-type Dirac bands near the Fermi level facilitate high and strong energy-dependent hole relaxation time; (ii) the presence of additional parabolic conduction valleys allows for a large density of states to accept scattered electrons, leading to an enlarged hole-electron relaxation time ratio and, thus, weakened bipolar effect. In combination with the strong lattice anharmonicity, an exceptional p-type average ZT of 0.42 is achieved from 300 to 600 K, which can be dramatically enhanced to 1.38 via breaking the C-3v symmetry. This work uncovers the underlying mechanisms governing the abnormal transport behavior in Dirac semimetal BaAgBi and highlights the asymmetric electronic structures as target features to discover/design high-performance thermoelectric materials.
DOI10.1021/acs.jpclett.2c00379
发表期刊JOURNAL OF PHYSICAL CHEMISTRY LETTERS
ISSN1948-7185
卷号13期号:10页码:2291-2298
通讯作者Lu, Xu(luxu@cqu.edu.cn) ; Wang, Guoyu(guoyuw@cigit.ac.cn) ; Zhou, Xiaoyuan(xiaoyuan2013@cqu.edu.cn)
收录类别SCI
WOS记录号WOS:000776518000004
语种英语