Manipulation of Band Structure and Interstitial Defects for Improving Thermoelectric SnTe
Manipulation of Band Structure and Interstitial Defects for Improving Thermoelectric SnTe
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调控能带结构和间隙缺陷以改善热电 SnTe
DOI：
10.1002/adfm.201803586
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发表时间：
2018-08-22
影响因子：
19
通讯作者：
Pei, Yanzhong
中科院分区：
文献类型：
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作者：
Tang, Jing;Gao, Bo;Pei, Yanzhong
许多努力最近致力于改善热电SnTe作为一种环境友好的替代传统的PbTe和成功的方法，包括价带收敛，纳米结构，和大量/间隙缺陷。在这些策略中，SnTe与MnTe的合金化使得能够最有效地减少价带偏移（在L和σ之间），以用于收敛，这是由于其近似15%的高溶解度，但是没有迹象表明MnTe的溶解度足够高以用于完全优化价带结构，从而用于最大化电子性能。在这里，示出了一种策略，以增加MnTe的溶解度高达约25%的合金与5%的GeTe，成功地定位的组合物（20%MnTe），以优化的价带结构，通过收敛更多的退化（与带L相比）和西格玛价带。通过与Cu 2 Te的进一步合金化，所得到的Cu间隙缺陷使得晶格热导率能够充分降低到其非晶极限（0.4W m（-1）K-1）。这些电子和热效应成功地实现了创纪录的高热电优值，zT为1.8，与PbTe的热电优值竞争激烈。这项工作证明了能带操纵和间隙缺陷的有效性，实现非凡的热电性能在SnTe。
Many efforts are recently devoted on improving thermoelectric SnTe as an environmentfriendly alternative to conventional PbTe and successful approaches include valence band convergence, nanostructuring, and substantial/interstitial defects. Among these strategies, alloying SnTe with MnTe enables the most effective reduction in the valence band offset (between L and Sigma) for a convergence due to its high solubility of approximate to 15%, yet there is no indication that the solubility of MnTe is high enough for fully optimizing the valence band structure and thus for maximizing the electronic performance. Here, a strategy is shown to increase the MnTe solubility up to approximate to 25% by alloying with 5% GeTe, which successfully locates the composition (20% MnTe) to optimize the valence band structure by converging a more degenerated (as compared with band L) and Sigma valence bands. Through a further alloying with Cu2Te, the resultant Cu-interstitial defects enable a sufficient reduction in lattice thermal conductivity to its amorphous limit (0.4 W m(-1) K-1). These electronic and thermal effects successfully realize a record-high thermoelectric figure of merit, zT of 1.8, strongly competing with that of PbTe. This work demonstrates the validity of band manipulation and interstitial defects for realizing extraordinary thermoelectric performance in SnTe.