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High-Power Factor Enabled by Efficient Manipulation Interaxial Angle for Enhancing Thermoelectrics of GeTe-Cu2Te Alloys
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2023-02-10 , DOI: 10.1021/acsami.2c20740 Xiaobo Tan 1 , Fujie Zhang 1 , Jianglong Zhu 1 , Fang Xu 1 , Ruiheng Li 1 , Shan He 1 , Xuri Rao 1 , Ran Ang 1, 2
ACS Applied Materials & Interfaces ( IF 8.3 ) Pub Date : 2023-02-10 , DOI: 10.1021/acsami.2c20740 Xiaobo Tan 1 , Fujie Zhang 1 , Jianglong Zhu 1 , Fang Xu 1 , Ruiheng Li 1 , Shan He 1 , Xuri Rao 1 , Ran Ang 1, 2
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The emerged strategy of manipulating the rhombohedral crystal structure provides another new degree of freedom for optimizing the thermoelectric properties of GeTe-based compounds. However, the concept is difficult to be effectively measured and often depends on heavy doping that scatters carriers severely. Herein, we synergistically manipulate lattice distortion and vacancy concentration to promote the excellent electrical transport of GeTe-Cu2Te alloys and quantify the interaxial angle-dependent density of state effective mass. Distinct from the conventional electronic coupling effect, about 2% substitution of Zr4+ significantly increases the interaxial angle, thereby enhancing the band convergence effect and improving the Seebeck coefficient. In addition, Ge-compensation attenuates the mobility deterioration, leading to improved power factor over the whole temperature range, especially exceeding ∼22 μW cm–1 K–2 at 300 K. Furthermore, the Debye–Callaway model elucidates low lattice thermal conductivity due to strong phonon scattering from Zr/Ge substitutional defects. As a result, the highest figure of merit zT of ∼1.6 (at 650 K) and average zTave of ∼0.9 (300–750 K) are obtained in (Ge1.01Zr0.02Te)0.985(Cu2Te)0.015. This work demonstrates the effective band modulation of Zr on GeTe-based materials, indicating that the modification of the interaxial angle is a deep pathway to improve thermoelectrics.
中文翻译：
通过有效操纵轴间角实现高功率因数，增强 GeTe-Cu2Te 合金的热电性能
操纵菱面体晶体结构的新策略为优化 GeTe 基化合物的热电性能提供了另一个新的自由度。然而，这个概念很难有效测量，并且通常依赖于严重散射载流子的重掺杂。在此，我们协同控制晶格畸变和空位浓度，以促进GeTe-Cu 2 Te合金优异的电输运，并量化轴间角相关的状态有效质量密度。与传统的电子耦合效应不同，约2%的Zr 4+替代显着增加了轴间角，从而增强了能带会聚效应并提高了塞贝克系数。此外，Ge 补偿可减轻迁移率恶化，从而在整个温度范围内提高功率因数，特别是在 300 K 时超过 ∼22 μW cm –1 K –2 。此外，Debye-Callaway 模型阐明了由于晶格热导率较低Zr/Ge 替代缺陷引起的强声子散射。结果，在 (Ge 1.01 Zr 0.02 Te) 0.985 (Cu 2 Te) 0.015中获得了最高品质因数zT ～1.6（在 650 K 时）和平均zT ave ～0.9（300–750 K）。这项工作证明了Zr对GeTe基材料的有效能带调制，表明轴间角的修改是改善热电性的深层途径。
更新日期：2023-02-10
中文翻译：
通过有效操纵轴间角实现高功率因数，增强 GeTe-Cu2Te 合金的热电性能
操纵菱面体晶体结构的新策略为优化 GeTe 基化合物的热电性能提供了另一个新的自由度。然而，这个概念很难有效测量，并且通常依赖于严重散射载流子的重掺杂。在此，我们协同控制晶格畸变和空位浓度，以促进GeTe-Cu 2 Te合金优异的电输运，并量化轴间角相关的状态有效质量密度。与传统的电子耦合效应不同，约2%的Zr 4+替代显着增加了轴间角，从而增强了能带会聚效应并提高了塞贝克系数。此外，Ge 补偿可减轻迁移率恶化，从而在整个温度范围内提高功率因数，特别是在 300 K 时超过 ∼22 μW cm –1 K –2 。此外，Debye-Callaway 模型阐明了由于晶格热导率较低Zr/Ge 替代缺陷引起的强声子散射。结果，在 (Ge 1.01 Zr 0.02 Te) 0.985 (Cu 2 Te) 0.015中获得了最高品质因数zT ～1.6（在 650 K 时）和平均zT ave ～0.9（300–750 K）。这项工作证明了Zr对GeTe基材料的有效能带调制，表明轴间角的修改是改善热电性的深层途径。
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