Liquid/Solid Metal Processing Institute, School of Materials Science & Engineering , Hefei University of Technology , Hefei 230009 , China.
Experimental Center of Engineering and Material Sciences , University of Science and Technology of China , Hefei 230027 , China.
ACS Appl Mater Interfaces. 2018 Jul 11;10(27):23277-23284. doi: 10.1021/acsami.8b01719. Epub 2018 Jun 27.
Interface engineering has been demonstrated to be an effective strategy for enhancing the thermoelectric (TE) performance of materials. However, a very typical interface in semiconductors, that is, the PN junction (PNJ), is scarcely adopted by the thermoelectrical community because of the coexistence of holes and electrons. Interestingly, our explorative results provide a definitively positive case that appropriate PNJs are able to enhance the TE performance of p-type SbTe-based alloys. Specifically, owing to the formation of the charge-depletion layer and built-in electric field, the carrier concentration and transport can be optimized and thus the power factor is improved and the electronic thermal conductivity is decreased. Meanwhile, PNJs provide scattering centers for phonons, leading to a reduced lattice thermal conductivity. Consequently, the p-type (BiTe)-(SbTe) composites comprising PNJs achieve a ∼131% improvement of the ZT value compared with the pure SbTe. The increased ZT demonstrates the feasibility of improving the TE properties by introducing PNJs, which will open a new and effective avenue for designing TE alloys with high performance.
界面工程已被证明是提高材料热电（TE）性能的有效策略。然而，由于空穴和电子的共存，半导体中一种非常典型的界面，即 PN 结（PNJ），很少被热电领域采用。有趣的是，我们的探索性结果提供了一个明确的正面案例，即适当的 PNJ 能够提高 p 型 SbTe 基合金的 TE 性能。具体来说，由于电荷耗尽层和内置电场的形成，载流子浓度和输运可以得到优化，从而提高功率因子并降低电子热导率。同时，PNJ 为声子提供了散射中心，导致晶格热导率降低。因此，包含 PNJ 的 p 型（BiTe）-（SbTe）复合材料的 ZT 值与纯 SbTe 相比提高了约 131%。增加的 ZT 表明通过引入 PNJ 来提高 TE 性能是可行的，这将为设计高性能的 TE 合金开辟一条新的、有效的途径。
