Surfactant-Free Synthesis of Bi2Te3−Te Micro−Nano Heterostructure with Enhanced Thermoelectric Figure of Merit

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• 作者：Yichi Zhang ; Heng Wang ; Stephan Kräemer ; Yifeng Shi ; Fan Zhang ; Matt Snedaker ; Kunlun Ding ; Martin Moskovits ; G. Jeffrey Snyder ; Galen D. Stucky
• 刊名：ACS Nano
• 出版年：2011
• 出版时间：April 26, 2011
• 年：2011
• 卷：5
• 期：4
• 页码：3158-3165
• 全文大小：1020K
• 年卷期：0
• ISSN：1936-086X

文摘

An ideal thermoelectric material would be a semiconductor with high electrical conductivity and relatively low thermal conductivity: an “electron crystal, phonon glass”. Introducing nanoscale heterostructures into the bulk TE matrix is one way of achieving this intuitively anomalous electron/phonon transport behavior. The heterostructured interfaces are expected to play a significant role in phonon scattering to reduce thermal conductivity and in the energy-dependent scattering of electrical carriers to improve the Seebeck coefficient. A nanoparticle building block assembly approach is plausible to fabricate three-dimensional heterostructured materials on a bulk commercial scale. However, a key problem in applying this strategy is the possible negative impact on TE performance of organic residue from the nanoparticle capping ligands. Herein, we report a wet chemical, surfactant-free, low-temperature, and easily up-scalable strategy for the synthesis of nanoscale heterophase Bi₂Te₃−Te via a galvanic replacement reaction. The micro−nano heterostructured material is fabricated bottom-up, by mixing the heterophase with commercial Bi₂Te₃. This unique structure shows an enhanced zT value of ∼0.4 at room temperature. This heterostructure has one of the highest figures of merit among bismuth telluride systems yet achieved by a wet chemical bottom-up assembly. In addition, it shows a 40% enhancement of the figure of merit over our lab-made material without nanoscale heterostructures. This enhancement is mainly due to the decrease in the thermal conductivity while maintaining the power factor. Overall, this cost-efficient and room-temperature synthesis methodology provides the potential for further improvement and large-scale thermoelectric applications.