High Thermoelectric Performance via Hierarchical Compositionally Alloyed Nanostructures

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• 作者：Li-Dong Zhao ; Shiqiang Hao ; Shih-Han Lo ; Chun-I Wu ; Xiaoyuan Zhou ; Yeseul Lee ; Hao Li ; Kanishka Biswas ; Timothy P. Hogan ; Ctirad Uher ; C. Wolverton ; Vinayak P. Dravid ; Mercouri G. Kanatzidis
• 刊名：The Journal of the American Chemical Society
• 出版年：2013
• 出版时间：May 15, 2013
• 年：2013
• 卷：135
• 期：19
• 页码：7364-7370
• 全文大小：527K
• 年卷期：v.135,no.19(May 15, 2013)
• ISSN：1520-5126

文摘

Previous efforts to enhance thermoelectric performance have primarily focused on reduction in lattice thermal conductivity caused by broad-based phonon scattering across multiple length scales. Herein, we demonstrate a design strategy which provides for simultaneous improvement of electrical and thermal properties of p-type PbSe and leads to ZT 1.6 at 923 K, the highest ever reported for a tellurium-free chalcogenide. Our strategy goes beyond the recent ideas of reducing thermal conductivity by adding two key new theory-guided concepts in engineering, both electronic structure and band alignment across nanostructure鈥搈atrix interface. Utilizing density functional theory for calculations of valence band energy levels of nanoscale precipitates of CdS, CdSe, ZnS, and ZnSe, we infer favorable valence band alignments between PbSe and compositionally alloyed nanostructures of CdS_1鈥?i>xSe_x/ZnS_1鈥?i>xSe_x. Then by alloying Cd on the cation sublattice of PbSe, we tailor the electronic structure of its two valence bands (light hole L and heavy hole 危) to move closer in energy, thereby enabling the enhancement of the Seebeck coefficients and the power factor.