Sun Shucui, Li Yiwei, Chen Yujie, Xu Xiang, Kang Lu, Zhou Jingsong, Xia Wei, Liu Shuai, Wang Meixiao, Jiang Juan, Liang Aiji, Pei Ding, Zhao Kunpeng, Qiu Pengfei, Shi Xun, Chen Lidong, Guo Yanfeng, Wang Zhengguo, Zhang Yan, Liu Zhongkai, Yang Lexian, Chen Yulin
State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China.
Department of Physics, Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, UK.
Sci Bull (Beijing). 2020 Nov 30;65(22):1888-1893. doi: 10.1016/j.scib.2020.07.007. Epub 2020 Jul 7.
Thermoelectric materials (TMs) can uniquely convert waste heat into electricity, which provides a potential solution for the global energy crisis that is increasingly severe. Bulk CuSe, with ionic conductivity of Cu ions, exhibits a significant enhancement of its thermoelectric figure of merit zT by a factor of ~3 near its structural transition around 400 K. Here, we show a systematic study of the electronic structure of CuSe and its temperature evolution using high-resolution angle-resolved photoemission spectroscopy. Upon heating across the structural transition, the electronic states near the corner of the Brillouin zone gradually disappear, while the bands near the centre of Brillouin zone shift abruptly towards high binding energies and develop an energy gap. Interestingly, the observed band reconstruction well reproduces the temperature evolution of the Seebeck coefficient of CuSe, providing an electronic origin for the drastic enhancement of the thermoelectric performance near 400 K. The current results not only bridge among structural phase transition, electronic structures and thermoelectric properties in a condensed matter system, but also provide valuable insights into the search and design of new generation of thermoelectric materials.
热电材料（TMs）能够独特地将废热转化为电能，这为日益严峻的全球能源危机提供了一种潜在的解决方案。具有铜离子离子导电性的块状硒化铜（CuSe），在其约400K的结构转变附近，其热电优值zT显著提高了约3倍。在此，我们展示了利用高分辨率角分辨光电子能谱对CuSe的电子结构及其温度演化进行的系统研究。在加热通过结构转变时，布里渊区角附近的电子态逐渐消失，而布里渊区中心附近的能带突然向高结合能移动并形成能隙。有趣的是，观察到的能带重构很好地再现了CuSe的塞贝克系数的温度演化，为400K附近热电性能的急剧增强提供了电子起源。当前结果不仅在凝聚态系统中的结构相变、电子结构和热电性质之间架起了桥梁，而且为新一代热电材料的探索和设计提供了有价值的见解。
