Thermoelectric (TE) devices enable robust solid-state conversion of waste heat to electricity, but their wide-spread adoption is still limited by relatively modest efficiency. A widely used approach to improve efficiency is to enhance the power factor through confinement of carriers or energy filtering by potential barriers. However, their relative influence and the resulting improvement in the power factor in two-dimensional (2D) materials is not well understood. Here we study single-layer 2D ${\mathrm{Mo}\mathrm{S}}_2$ with lateral potential barriers to introduce either energy filtering or carrier confinement by changing the direction of the electric field, with confinement resulting when the electric field is parallel and energy filtering when the electric field is perpendicular to the potential barriers. We implement a Wigner-Rode model with electronic structure calculated from first principles to simulate the effect of the shape and size of potential barriers on parallel and perpendicular transport. Our results show that the power factor can be doubled, from $25{\mathrm{mWm}}^{-1}{\mathrm{K}}^{-2}$ without barriers to over $50{\mathrm{mWm}}^{-1}{\mathrm{K}}^{-2}$ for parallel transport in sharp, narrow potential wells. Perpendicular transport in smooth barriers results in a higher power factor compared to sharp barriers, while sharp barriers perform better in the case of transport parallel to the barriers, especially at small barrier widths. Our results aid in improving TE power factors and further the development of efficient waste-heat scavenging, flexible 2D TE converters, and Peltier cooling of nanoelectronics.

中文翻译：

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具有周期性势垒的二维材料的各向异性热电功率因数：Wigner-Rode形式主义

热电（TE）器件可实现将废热可靠地固态转换为电，但是其广泛采用仍然受到效率相对较低的限制。一种广泛使用的提高效率的方法是通过限制载流子或通过势垒过滤能量来提高功率因数。但是，它们在二维（2D）材料中的相对影响以及功率因数的改善尚不十分清楚。在这里我们研究单层2D${莫\mathrm{小号}}_2$具有横向势垒以通过改变电场的方向引入能量滤波或载流子限制，其中当电场平行时限制，而当电场垂直于势垒时进行能量过滤。我们使用从第一原理计算得出的电子结构来实现Wigner-Rode模型，以模拟势垒的形状和大小对平行和垂直传输的影响。我们的结果表明，功率因数可以从$25{\mathrm{兆瓦}}^{-\mathrm{1个}}{\mathrm{ķ}}^{-2}$ 无障碍 $50{\mathrm{兆瓦}}^{-\mathrm{1个}}{\mathrm{ķ}}^{-2}$可以在尖锐，狭窄的潜在井中平行运输。与锋利的障碍物相比，在光滑障碍物中的垂直输送会导致更高的功率因数，而在平行于障碍物的情况下，尤其是在较小的障碍物宽度下，锋利的障碍物的性能会更好。我们的结果有助于改善TE功率因数，并进一步发展高效的废热清除，灵活的2D TE转换器和纳米电子学的珀耳帖冷却。