论文标题
当频带收敛对热电学不利时
When Band Convergence is Not Beneficial for Thermoelectrics
论文作者
论文摘要
频带收敛被认为是热电性能的明显好处，因为它增加了给定费米水平的电荷载体浓度，这通常在保留Seebeck系数的同时提高电荷电导率。但是，这种优势取决于载体间散射较弱或微不足道的假设。首先对CAMG $ _ {2} $ sb $ _ {2} $ _ {2} $ - CAZN $ _ {2} $ _ {2} $ sb $ _ {2} $ zintl系统和全力助Sr $ _ {2} $ sbau的效果，我们可以互联cortion corternins contractions contractions camg $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ _ {2} $ - 乐队收敛。在Zintl合金中，带收敛不会改善加权迁移率或状态密度的有效质量。我们将基本原因追踪到以下事实：频带以一个K点收敛，从而诱导变形电位和极光电类型的频带间散射。该案例与遥远的K点（如全赫斯勒）处的频带收敛形成对比，后者更好地保留了单带散射行为，从而成功地导致了改善的性能。因此，我们建议带作为热电设计原理的条带收敛最适合在远处K点发生的情况。
Band convergence is considered a clear benefit to thermoelectric performance because it increases the charge carrier concentration for a given Fermi level, which typically enhances charge conductivity while preserving the Seebeck coefficient. However, this advantage hinges on the assumption that interband scattering of carriers is weak or insignificant. With first-principles treatment of electron-phonon scattering in CaMg$_{2}$Sb$_{2}$-CaZn$_{2}$Sb$_{2}$ Zintl system and full Heusler Sr$_{2}$SbAu, we demonstrate that the benefit of band convergence can be intrinsically negated by interband scattering depending on the manner in which bands converge. In the Zintl alloy, band convergence does not improve weighted mobility or the density-of-states effective mass. We trace the underlying reason to the fact that the bands converge at one k-point, which induces strong interband scattering of both the deformation-potential and the polar-optical kinds. The case contrasts with band convergence at distant k-points (as in the full Heusler), which better preserves the single-band scattering behavior thereby successfully leading to improved performance. Therefore, we suggest that band convergence as thermoelectric design principle is best suited to cases in which it occurs at distant k-points.
