Enhancing p-Type Thermoelectric Performances of Polycrystalline SnSe via Tuning Phase Transition Temperature
Enhancing p-Type Thermoelectric Performances of Polycrystalline SnSe via Tuning Phase Transition Temperature
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DOI：
10.1021/jacs.7b05881
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发表时间：
2017-08-09
影响因子：
15
通讯作者：
Chung, In
中科院分区：
文献类型：
--
作者：
Lee, Yong Kyu;Ahn, Kyunghan;Chung, In
硒化锡是一种新型的热电材料，其单晶体具有良好的热电优值。在多晶对应物中实现这样的性能仍然具有挑战性，并且需要对其电和热传输特性以及结构化学的基本理解。在这里，我们展示了一种新的策略，提高转换效率的块状多晶SnSe热弹性体。我们表明，PbSe合金化降低Pnma和Cmcm相之间的转变温度，从而可以作为一种手段，控制其起始温度。沿着1%的Na掺杂，合金化分数的精细控制通过较早地引发双极传导而显著地增强电导率，同时通过合金和点缺陷散射降低晶格热导率。结果表明，对于Na-0.01（Sn 1-xPbx）（0.99）Se，在773 K时具有接近1.2的显著高峰ZT，从室温到773 K的平均ZT接近0.5。令人惊讶的是，球差校正的扫描透射电子显微镜研究表明，NaySn 1-xPbxSe（0
SnSe emerges as a new class of thermoelectric materials since the recent discovery of an ultrahigh thermoelectric figure of merit in its single crystals. Achieving such performance in the polycrystalline counterpart is still challenging and requires fundamental understandings of its electrical and thermal transport properties as well as structural chemistry. Here we demonstrate a new strategy of improving conversion efficiency of bulk polycrystalline SnSe thermoelethics. We show that PbSe alloying decreases the transition temperature between Pnma and Cmcm phases and thereby can serve as a means of controlling its onset temperature. Along with 1% Na doping, delicate control of the alloying fraction markedly enhances electrical conductivity by earlier initiation of bipolar conduction while reducing lattice thermal conductivity by alloy and point defect scattering simultaneously. As a result, a remarkably high peak ZT of similar to 1.2 at 773 K as well as average ZT of similar to 0.5 from RT to 773 K is achieved for Na-0.01(Sn1-xPbx)(0.99)Se. Surprisingly, spherical-aberration corrected scanning transmission electron microscopic studies reveal that NaySn1-xPbxSe (0 < x