High-Temperature Thermoelectricity in Narrow-Gap Semiconductor SmS with Strong Electron-Hole Asymmetry
High-Temperature Thermoelectricity in Narrow-Gap Semiconductor SmS with Strong Electron-Hole Asymmetry
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具有强电子空穴不对称性的窄带隙半导体 SmS 中的高温热电
DOI：
10.1002/aenm.202203519
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发表时间：
2023
期刊：
影响因子：
--
通讯作者：
xiaoyuan Zhou
中科院分区：
文献类型：
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作者：
Huijun Liao;Zizhen Zhou;Sikang Zheng;Yuling Huang;Guang Han;Guoyu Wang;hengyong Huang;Xu Lu;Jian Li;xiaoyuan Zhou
高温热电（TE）材料是常见的宽禁带半导体，用于防止双极效应。在这里，报道了具有简单NaCl结构的潜在高温型TE材料SmS，其显示出小于0.25 eV的窄带隙。正如预期的那样，观察到依赖于温度的载流子聚集，这归因于电子从价带边缘到导带的热激活。有趣的是，内在激活不会引起任何双极效应的迹象。密度泛函理论计算表明，这种现象源于电子结构中强烈的电子-空穴不对称性，电子-空穴电导率比高达700-900。结果表明，在1123 K时，激活的少数载流子几乎不参与TE输运，最大功率因数达到1.41 mW K-2 m-1。通过进一步与Se合金化以降低晶格热导率，Sm1.08S0.78Se0.22在1123 K下获得了1.1的峰值zT，这是最好的n型高温热电材料之一。这项研究证明了高温TE材料可以在窄禁带半导体中找到，这大大丰富了新型TE材料的可能性范围。
High‐temperature thermoelectric (TE) materials are common wide‐gap semiconductors that are used in order to prevent the bipolar effect. Here, a potential high‐temperaturen‐type TE material SmS with a simple NaCl structure that demonstrates a narrow band gap of ≈0.25 eV is reported. As expected, a temperature‐dependent carrier concertation is observed, which is attributed to the thermal activation of electrons from valence band edge to conduction band. Interestingly, the intrinsic activation does not cause any sign of a bipolar effect. Density functional theory calculations suggest that the phenomenon originates from the strong electron‐hole asymmetry in the electronic structure and the electron‐to‐hole conductivity ratio is as high as 700–900. As a result, the activated minority carriers barely participate in the TE transport and the maximum power factor reaches 1.41 mW K−2m−1at 1123 K. By further alloying with Se to reduce lattice thermal conductivity, a peakzTof ≈1.1 is obtained in Sm1.08S0.78Se0.22at 1123 K, which is among the bestn‐type high‐temperature thermoelectrics. This study proves high‐temperature TE materials can be found in narrow‐gap semiconductors, which significantly enriches the scope of possibilities for novel TE materials.