Multiband convergence has attracted significant interest due to its positive effects on further improving thermoelectric performance. However, the current research mainly focuses on two- or three-band convergence in lead chalcogenides through doping and alloying. Therefore, exploring a new strategy to facilitate more-band convergence has instructive significance and practical value in thermoelectric research. Herein, we first propose a high-entropy strategy to achieve four-band convergence for optimizing thermoelectric performance. Taking high-entropy AgSbPbSnGeTe₅ as an example, we found that the emergence of more-band convergence occurs as the configuration entropy increases; in particular, the four-band convergence occurs in high-entropy AgSbPbSnGeTe₅. The overlap of multiatom orbitals in the high-entropy sample contributes to the convergence of four valence bands, promoting the improvement of electrical performance. Meanwhile, due to large lattice distortion and disordered atoms, the phonon mean free path is effectively compressed, resulting in low lattice thermal conductivity of high-entropy AgSbPbSnGeTe₅. Consequently, AgSbPbSnGeTe₅ achieved an intrinsically high ZT value of 1.22 at 673 K, providing a cornerstone for further optimizing thermoelectric performance. For example, by generally optimizing the carrier concentration, a peak ZT value of ∼1.75 at 723 K is achieved. These insights offer a comprehensive understanding of the band structure affected by unique structures of high-entropy materials and also shed useful light on innovation mechanisms and functionalities for future improvement of thermoelectric performance.

中文翻译：

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高熵策略实现高性能热电材料的电子能带收敛


多带收敛由于其对进一步提高热电性能的积极影响而引起了人们的极大兴趣。然而，目前的研究主要集中在通过掺杂和合金化实现铅硫族化物的两能带或三能带收敛。因此，探索促进多能带收敛的新策略对热电研究具有指导意义和实用价值。在这里，我们首先提出了一种高熵策略来实现四能带收敛以优化热电性能。以高熵AgSbPbSnGeTe ₅ 为例，我们发现随着构型熵的增加，出现了多能带收敛现象；特别是，四能带收敛发生在高熵 AgSbPbSnGeTe ₅ 中。高熵样品中多原子轨道的重叠有助于四个价带的收敛，促进电性能的提高。同时，由于较大的晶格畸变和无序原子，声子平均自由程被有效压缩，导致高熵AgSbPbSnGeTe ₅ 的晶格热导率较低。因此，AgSbPbSnGeTe ₅ 在 673 K 下实现了 1.22 的固有高 ZT 值，为进一步优化热电性能奠定了基础。例如，通过总体优化载流子浓度，可在 723 K 处实现~1.75 的峰值 ZT 值。这些见解提供了对受高熵材料独特结构影响的能带结构的全面理解，也为未来改进热电性能的创新机制和功能提供了有用的启示。