High-entropy semiconductors are now an important class of materials widely investigated for thermoelectric applications. Understanding the impact of chemical and structural heterogeneity on transport properties in these compositionally complex systems is essential for thermoelectric design. In this work, we uncover the polar domain structures in the high-entropy PbGeSnSe_1.5Te_1.5 system and assess their impact on thermoelectric properties. We found that polar domains induced by crystal symmetry breaking give rise to well-structured alternating strain fields. These fields effectively disrupt phonon propagation and suppress the thermal conductivity. We demonstrate that the polar domain structures can be modulated by tuning crystal symmetry through entropy engineering in PbGeSnAg_xSb_xSe_1.5+xTe_1.5+x. Incremental increases in the entropy enhance the crystal symmetry of the system, which suppresses domain formation and loses its efficacy in suppressing phonon propagation. As a result, the room-temperature lattice thermal conductivity increases from κ_L = 0.63 Wm^–1 K^–1 (x = 0) to 0.79 Wm^–1 K^–1 (x = 0.10). In the meantime, the increase in crystal symmetry, however, leads to enhanced valley degeneracy and improves the weighted mobility from μ_w = 29.6 cm² V^–1 s^–1 (x = 0) to 35.8 cm² V^–1 s^–1 (x = 0.10). As such, optimal thermoelectric performance can be achieved through entropy engineering by balancing weighted mobility and lattice thermal conductivity. This work, for the first time, studies the impact of polar domain structures on thermoelectric properties, and the developed understanding of the intricate interplay between crystal symmetry, polar domains, and transport properties, along with the impact of entropy control, provides valuable insights into designing GeTe-based high-entropy thermoelectrics.

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IV-VI 高熵热电材料中畴结构的意义和优化

高熵半导体现在是热电应用中广泛研究的一类重要材料。了解化学和结构异质性对这些成分复杂的系统中输运特性的影响对于热电设计至关重要。在这项工作中，我们揭示了高熵 PbGeSnSe _1.5 Te _1.5系统中的极性域结构，并评估了它们对热电性能的影响。我们发现晶体对称性破缺引起的极域会产生结构良好的交替应变场。这些场有效地破坏声子传播并抑制热导率。我们证明，可以通过 PbGeSnAg _x Sb _x Se _{1.5+ x} Te _{1.5+ x}中的熵工程调整晶体对称性来调制极性域结构。熵的逐渐增加增强了系统的晶体对称性，从而抑制了域的形成并失去了抑制声子传播的功效。结果，室温晶格热导率从 κ _L = 0.63 Wm ^–1 K ^–1 ( x = 0) 增加到 0.79 Wm ^–1 K ^–1 ( x = 0.10)。然而，与此同时，晶体对称性的增加导致谷简并性增强，并将加权迁移率从 μ _w = 29.6 cm ² V ^–1 s ^–1 ( x = 0) 提高到 35.8 cm ² V ^–1 s ^–1 ( x = 0.10)。因此，可以通过熵工程通过平衡加权迁移率和晶格热导率来实现最佳热电性能。这项工作首次研究了极域结构对热电性质的影响，以及对晶体对称性、极域和输运性质之间复杂相互作用的深入理解，以及熵控制的影响，为以下方面提供了宝贵的见解：设计基于 GeTe 的高熵热电材料。