Vertically stacked two-dimensional materials based on weak interactions have received significant attention because of possibilities of effective modulation of their electronic, transport, and optoelectronic performance. In this work, we systematically investigate the interlayer coupling effect in bilayer SnS, SnSe, and SnS/SnSe heterostructures, from the geometries to the electronic evolutions and thermoelectric properties, based on first-principles calculations and Boltzmann transport theory. The SnS/SnSe heterostructure shows a band structure more similar to that of the SnSe component and modulated charge transfer for the inner sublayer, as compared to the intrinsic bilayers. Furthermore, from monolayer to bilayer SnS and SnSe systems and the SnS/SnSe heterojunction, we discover different layer-dependent behaviors and coupling-modulation effects, which are prominent in the design of two-dimensional thermoelectric devices. The optimal power factor of SnS/SnSe superior to those of all other structures is found for the p-type doping along the armchair direction, within the carrier concentration range of 10¹⁹∼5 × 10²⁰ cm^–3 because of its small effective mass, moderate electron–phonon scattering, and enhanced elastic modulus. These findings indicate that heterointerlayer coupling could be a promising strategy for high-performance thermoelectric materials, beyond the size control.

中文翻译：

---

SnX（X = S或Se）双层膜和异质结构的输运和热电性能

由于有效调制其电子，传输和光电性能的可能性，基于弱相互作用的垂直堆叠二维材料已受到广泛关注。在这项工作中，我们基于第一性原理计算和玻尔兹曼输运理论，系统地研究了双层SnS，SnSe和SnS / SnSe异质结构中的层间耦合效应，从几何形状到电子演化和热电性质。与本征双层相比，SnS / SnSe异质结构的能带结构与SnSe组分的能带结构和内部子层的调制电荷转移更为相似。此外，从单层到双层SnS和SnSe系统以及SnS / SnSe异质结，我们发现了不同的层相关行为和耦合调制效应，这在二维热电器件的设计中很突出。对于沿扶手椅方向的p型掺杂，在10的载流子浓度范围内，发现SnS / SnSe的最佳功率因数优于所有其他结构。¹⁹〜5×10 ²⁰厘米^-3，因为其小的有效质量，中等电子-声子散射和增强的弹性模量。这些发现表明，异质夹层耦合可能是一种超越尺寸控制的高性能热电材料的有前途的策略。