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High ZT 2D Thermoelectrics by Design: Strong Interlayer Vibration and Complete Band‐Extrema Alignment
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2020-04-06 , DOI: 10.1002/adfm.202001200 Xiwen Zhang 1 , Chenhan Liu 2 , Yi Tao 2 , Yunhai Li 3 , Yilv Guo 3 , Yunfei Chen 1 , Xiao Cheng Zeng 4 , Jinlan Wang 1
Advanced Functional Materials ( IF 18.5 ) Pub Date : 2020-04-06 , DOI: 10.1002/adfm.202001200 Xiwen Zhang 1 , Chenhan Liu 2 , Yi Tao 2 , Yunhai Li 3 , Yilv Guo 3 , Yunfei Chen 1 , Xiao Cheng Zeng 4 , Jinlan Wang 1
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The discovery of a record high figure of merit (ZT) of ≈2.6 associated with bulk SnSe has stimulated considerable enthusiasm in searching for 2D systems with similar high ZT. However, previously reported 2D thermoelectric (TE) materials generally possess very low ZT due to the high lattice thermal conductivity (κL) and/or small power factor (PF). Herein, a very high ZT (≈2.08) value associated with atomically thin 2D KAgSe nanosheet is reported, which also exhibits an unprecedented low intrinsic κL (≈0.03 Wm−1 K−1 at 700 K for trilayer) and fairly large PF. The low κL mainly stems from the high lattice anharmonicity induced by both the “interfacial shear slip” vibrations and the asymmetric “AgSe pair” vibrations from distorted AgSe4 tetrahedrons. Meanwhile, the complete band‐extrema alignment and coexistence of heavy and light bands result in an optimal Seebeck coefficient and electrical conductivity, thereby a large PF. This work suggests not only an alternative way to acquiring high lattice anharmonicity but also a highly competitive 2D TE candidate for wide applications.
中文翻译：
高ZT 2D热电设计：强大的层间振动和完全的带极端对准
与块状SnSe相关的约2.6的创纪录高品质因数（ZT）的发现激发了人们在寻找具有相似高ZT的2D系统方面的热情。然而，先前报道的2D热电（TE）材料通常具有非常低的ZT由于高晶格热导率（κ大号）和/或小的功率因数（PF）。在本文中，一个非常高的ZT（≈2.08）与原子级薄的2D KAgSe纳米片相关联的值被报告，这也表现出前所未有的低特性κ大号（≈0.03了Wm -1 ķ -1在700 K中三层）和相当大的PF。低κ大号主要源于由“界面剪切滑动”振动和非对称“的Ag两者引起的高的晶格非谐扭曲的AgSe 4四面体引起的“ Se对”振动。同时，频带的极值完全对准以及重频带和轻频带的共存会导致最佳塞贝克系数和电导率，从而产生较大的PF。这项工作不仅提出了获得高晶格非谐性的另一种方法，而且还提出了具有广泛应用前景的极具竞争力的2D TE候选人。
更新日期：2020-04-06
中文翻译：
高ZT 2D热电设计：强大的层间振动和完全的带极端对准
与块状SnSe相关的约2.6的创纪录高品质因数（ZT）的发现激发了人们在寻找具有相似高ZT的2D系统方面的热情。然而，先前报道的2D热电（TE）材料通常具有非常低的ZT由于高晶格热导率（κ大号）和/或小的功率因数（PF）。在本文中，一个非常高的ZT（≈2.08）与原子级薄的2D KAgSe纳米片相关联的值被报告，这也表现出前所未有的低特性κ大号（≈0.03了Wm -1 ķ -1在700 K中三层）和相当大的PF。低κ大号主要源于由“界面剪切滑动”振动和非对称“的Ag两者引起的高的晶格非谐扭曲的AgSe 4四面体引起的“ Se对”振动。同时，频带的极值完全对准以及重频带和轻频带的共存会导致最佳塞贝克系数和电导率，从而产生较大的PF。这项工作不仅提出了获得高晶格非谐性的另一种方法，而且还提出了具有广泛应用前景的极具竞争力的2D TE候选人。
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