Weak electron-phonon coupling contributing to high thermoelectric performance in n-type PbSe
Weak electron-phonon coupling contributing to high thermoelectric performance in n-type PbSe
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DOI：
10.1073/pnas.1111419109
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发表时间：
2012-06-19
影响因子：
11.1
通讯作者：
Snyder, G. Jeffrey
中科院分区：
文献类型：
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作者：
Wang, Heng;Pei, Yanzhong;Snyder, G. Jeffrey
PbSe是一种令人惊讶的良好热电材料，部分原因是其热导率低，在早期的测量中被高估。热电品质因数zT在高温下在p型和n型PbSe中都可以超过1，类似于在PbTe中发现的热电品质因数。虽然p型铅硫族化物（PbSe和PbTe）受益于价带的高谷简并度（在高温下为12或更高），但n型版本限于导带中的谷简并度为4。然而，n型铅硫属化物实现几乎与p型铅硫属化物一样高的zT。这种效应可以归因于与价带中的电子-声子耦合相比，导带中的电子-声子耦合较弱（较低的变形势系数），这导致与空穴的迁移率相比，电子的迁移率较高。PbSe的这项研究说明了电荷携带带的变形势系数作为带结构工程和寻找高性能热电材料所需考虑的几个关键参数之一的重要性。
PbSe is a surprisingly good thermoelectric material due, in part, to its low thermal conductivity that had been overestimated in earlier measurements. The thermoelectric figure of merit, zT, can exceed 1 at high temperatures in both p-type and n-type PbSe, similar to that found in PbTe. While the p-type lead chalcogenides (PbSe and PbTe) benefit from the high valley degeneracy (12 or more at high temperature) of the valence band, the n-type versions are limited to a valley degeneracy of 4 in the conduction band. Yet the n-type lead chalcogenides achieve a zT nearly as high as the p-type lead chalcogenides. This effect can be attributed to the weaker electron-phonon coupling (lower deformation potential coefficient) in the conduction band as compared with that in the valence band, which leads to higher mobility of electrons compared to that of holes. This study of PbSe illustrates the importance of the deformation potential coefficient of the charge-carrying band as one of several key parameters to consider for band structure engineering and the search for high performance thermoelectric materials.