High Thermoelectric Performance of p-Type SnTe via a Synergistic Band Engineering and Nanostructuring Approach
High Thermoelectric Performance of p-Type SnTe via a Synergistic Band Engineering and Nanostructuring Approach
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DOI：
10.1021/ja500860m
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发表时间：
2014-05-14
影响因子：
15
通讯作者：
Kanatzidis, Mercouri G.
中科院分区：
文献类型：
--
作者：
Tan, Gangjian;Zhao, Li-Dong;Kanatzidis, Mercouri G.
SnTe是一种潜在的有吸引力的热电材料，因为它是PbTe的无铅岩盐类似物。然而，SnTe是一种差的热电材料，因为其由晶格中固有的Sn空位引起的高空穴浓度以及其非常高的电导率和热导率。在这项研究中，我们证明了SnTe基材料可以通过成功应用几个关键概念来控制，使其成为优秀的热电发电材料，这些关键概念可以克服SnTe的众所周知的缺点。首先，我们证明了Sn自补偿可以有效地减少Sn空位，降低空穴载流子密度。例如，Sn的3摩尔%自补偿导致品质因数ZT提高50%。此外，我们发现，镉，名义上与锡等电子，有利地影响电子能带结构（a）减少轻空穴和重空穴价带之间的能量分离的材料，导致增强塞贝克系数，和（B）扩大能带隙。因此，与Cd原子的合金化能够实现一种形式的价带工程，其改善了高温热电性能，其中SnCd0.03Te的p型样品在823 K下表现出类似于0.96的ZT值，比无Cd样品改善了60%。最后，我们引入内轴CdS或ZnS纳米沉淀物，降低了SnCd 0.03Te的晶格热导率，而对功率因数没有影响。我们报告说，SnCd0.03Te是endotaxially纳米结构的CdS和ZnS有一个最大的ZT类似于1.3和类似于1.1在873 K，分别。因此，SnTe基材料可能是p型铅硫族化合物的理想替代品，用于高温热电发电。
SnTe is a potentially attractive thermoelectric because it is the lead-free rock-salt analogue of PbTe. However, SnTe is a poor thermoelectric material because of its high hole concentration arising from inherent Sn vacancies in the lattice and its very high electrical and thermal conductivity. In this study, we demonstrate that SnTe-based materials can be controlled to become excellent thermoelectrics for power generation via the successful application of several key concepts that obviate the well-known disadvantages of SnTe. First, we show that Sn self-compensation can effectively reduce the Sn vacancies and decrease the hole carrier density. For example, a 3 mol % self-compensation of Sn results in a 50% improvement in the figure of merit ZT. In addition, we reveal that Cd, nominally isoelectronic with Sn, favorably impacts the electronic band structure by (a) diminishing the energy separation between the light-hole and heavy-hole valence bands in the material, leading to an enhanced Seebeck coefficient, and (b) enlarging the energy band gap. Thus, alloying with Cd atoms enables a form of valence band engineering that improves the high-temperature thermoelectric performance, where p-type samples of SnCd0.03Te exhibit ZT values of similar to 0.96 at 823 K, a 60% improvement over the Cd-free sample. Finally, we introduce endotaxial CdS or ZnS nanoscale precipitates that reduce the lattice thermal conductivity of SnCd0.03Te with no effect on the power factor. We report that SnCd0.03Te that are endotaxially nanostructured with CdS and ZnS have a maximum ZTs of similar to 1.3 and similar to 1.1 at 873 K, respectively. Therefore, SnTe-based materials could be ideal alternatives for p-type lead chalcogenides for high temperature thermoelectric power generation.