Optimizing n-type PbTe thermoelectric materials to match their better-performing p-type counterparts is critical for realizing their practical applications. To overcome this gap, dynamic doping, due to its temperature-dependent self-optimizing carrier concentration, has recently arisen as an effective method to improve the performance of n-type PbTe. However, their evitable dynamic compositional evolution must lead to structure evolution at elevated temperatures, which may have a negative effect on suppressing phonon transport, verified by the observed high lattice thermal conductivity (κ_lat) of Ag-doped n-type PbTe. Herein, we describe the significance of Mn alloying in enhancing the performance of Ag-doped n-type PbTe by creating a hierarchical structure to suppress thermal transport and improving the Seebeck coefficient by flattening the L point of the conduction band. Systematic characterization analysis reveals that the constructed hierarchical structure primarily consists of Ag₂Te-decorated grain boundaries, dispersive MnTe nanoprecipitates, and atomic disorders induced by multi-doping in the matrix, which significantly suppressed κ_lat across the entire temperature range. In consequence, a high ZT ∼1.4 of Ag_0.03Pb_0.95Mn_0.05Te at 773 K and an average ZT ∼0.8 of Ag_0.03Pb_0.99Mn_0.01Te in the range of 323–823 K were obtained, which were ascribed to the weakening of the coupling between electron and phonon transport. This work demonstrates an upgraded approach to enhance the thermoelectric performance of dynamically-doped PbTe materials through unique structural design, which can be applied to other thermoelectric material systems with high performance.

中文翻译：

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协同载流子和声子输运通过锰合金化促进Ag动态掺杂n型PbTe热电材料


优化 n 型 PbTe 热电材料以匹配性能更好的 p 型热电材料对于实现其实际应用至关重要。为了克服这一差距，动态掺杂由于其与温度相关的自优化载流子浓度，最近成为提高 n 型 PbTe 性能的有效方法。然而，它们不可避免的动态成分演化必然导致高温下的结构演化，这可能对抑制声子输运产生负面影响，这一点已通过观察到的Ag掺杂n的高晶格热导率（κ _lat ）得到证实。型PbTe。在此，我们描述了Mn合金化通过创建分层结构来抑制热传输并通过平坦化导带的L点来提高塞贝克系数来增强Ag掺杂n型PbTe的性能的重要性。系统表征分析表明，所构建的分级结构主要由 Ag ₂ Te 修饰的晶界、分散的 MnTe 纳米沉淀物以及基体中多重掺杂引起的原子紊乱组成，显着抑制了 κ _lat Pb _0.95 Mn _0.05 Te 在 773 K 时的 ZT 高达 ∼1.4，Ag _0.03 Mn _0.01 Te在323-823 K范围内得到，这归因于电子和声子输运之间的耦合减弱。这项工作展示了一种通过独特的结构设计增强动态掺杂PbTe材料热电性能的升级方法，可应用于其他高性能热电材料系统。