Low-dimensional thermoelectricity
Low-dimensional thermoelectricity
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DOI：
10.12693/aphyspola.108.609
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发表时间：
2005-10-01
影响因子：
0.7
通讯作者：
Heremans, JP
中科院分区：
文献类型：
--
作者：
Heremans, JP
热电材料被用作固态热泵和发电机。基于常规块体热电材料的器件的低效率将它们的应用限制在小生境中，在小生境中它们在紧凑性和可控性方面的优点超过了该缺点。纳米技术的最新发展导致热电纳米材料的开发，其效率是最好的散装材料的两倍，为热电能量转换技术开辟了几个新的应用类别。我们在这里首先审查的物理机制，导致在上级热电性能的低维固体，相比散装热电材料：它们是晶格热导率的减少，并在塞贝克系数S的增加，对于一个给定的载流子密度。本文的第二部分总结了铋，锑和锌纳米线的直径范围从200到7纳米的宏观阵列上获得的实验结果。我们展示了尺寸量子化效应如何大大增加S对于一个给定的载流子浓度，只要纳米线的直径保持在9 nm以上，低于此本地化效应开始占主导地位。在第三部分中，我们给出了PbTe纳米复合材料的数据，特别是含有30 nm直径的Pb夹杂物的散装样品。这些夹杂物影响电子散射的方式，再次增加塞贝克系数。
Thermoelectric materials are used as solid-state heat pumps and as power generators. The low efficiency of devices based on conventional bulk thermoelectric materials confines their applications to niches in which their advantages in compactness and controllability outweigh that drawback. Recent developments in nanotechnologies have led to the development of thermoelectric nano-materials with double the efficiency of the best bulk materials, opening several new classes of applications for thermoelectric energy conversion technology. We review here first the physical mechanisms that result in the superior thermoelectric performance of low-dimensional solids, compared to bulk thermoelectric materials: they are a reduction of the lattice thermal conductivity, and an increase in the Seebeck coefficient S for a given carrier density. The second part of this review summarizes experimental results obtained on macroscopic arrays of bismuth, antimony, and zinc nanowires with diameters ranging from 200 to 7 nm. We show how size-quantization effects greatly increase S for a given carrier concentration, as long as the diameter of the nanowires remains above 9 nm, below which localization effects start dominating. In a third part, we give data on PbTe nanocomposites, particularly bulk samples containing 30 nm diameter Pb inclusions. These inclusions affect the electron scattering in such a way as to again increase the Seebeck coefficient.