On the applicability of the single parabolic band model to advanced thermoelectric materials with complex band structures
On the applicability of the single parabolic band model to advanced thermoelectric materials with complex band structures
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DOI：
10.1016/j.jmat.2020.10.013
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发表时间：
2021-01-23
影响因子：
9.4
通讯作者：
de Boor, Johannes
中科院分区：
文献类型：
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作者：
de Boor, Johannes
由于热电材料的组成、合成参数与性能之间存在复杂的相互作用，因此热电材料的优化需要辅以建模。一种相对简单而流行的方法是所谓的单抛物线带模型，它允许有效地优化材料特性，并基于相对较少的、可用的实验结果对不同材料进行基准测试。由于复杂的能带结构在高性能材料中很常见，单抛物线能带建模也被用于材料系统，在这些材料系统的基本假设没有很好地满足的情况下取得了明显的成功。为了评估这种系统的单抛物带分析的有效性，计算了两种模型系统的热电性质：一种是双退化的单带，另一种是轻带和重带。即使态密度、质量和散射势保持相同，输运性质，特别是霍尔系数也会显著不同，从而导致不正确地确定载流子浓度。由于载流子浓度是单抛物带分析的基础，由此得到的所有量（最佳载流子浓度、有效质量、变形势）也都是不正确的。(C) 2020中国陶瓷学会。制作和托管由爱思唯尔B.V.
Due to the complex interplay between composition, synthesis parameters and the performance of thermoelectric materials, the optimization of thermoelectric materials needs to be complemented by modelling. A relatively simple and thus popular approach is the so called single parabolic band model, which allows for an efficient optimization of the material properties and a benchmarking of different materials based on relatively few, well available experimental results. As complex band structures are common for high performance materials, single parabolic band modelling is also employed with apparent success for material systems where the underlying assumptions are not well fulfilled. In order to assess the validity of a single parabolic band analysis for such systems, the thermoelectric properties for two model systems are calculated: one with a single band that is twofold degenerate and one with a light and a heavy band. Even if the density of states masses and the scattering potentials are kept identical, the transport properties and in particular the Hall coefficients differ significantly, which leads to an incorrectly determined carrier concentration. As the carrier concentration is the base for the single parabolic band analysis, all the quantities obtained from it (optimum carrier concentration, effective mass, deformation potential) are determined incorrectly as well. (C) 2020 The Chinese Ceramic Society. Production and hosting by Elsevier B.V.