Designing and discovering superior type-II band alignment are crucial for advancing optoelectronic device technologies. Here, we employ first-principles calculations to investigate the evolution of band edges in monolayer MoS₂, boron phosphide (BP), and MoS₂/BP heterostructures before and after their rolling into nanotubes. Our research results indicate that the intrinsic MoS₂/BP vertical heterostructures exhibit a type-II direct bandgap, but this feature is not robust under strain. For MoS₂/BP coaxial heterotubes, the type of bandgap is influenced by both chirality and diameter. Specifically, when the diameter exceeds 19 Å under zigzag chirality, the system undergoes a transition from a type-I direct bandgap to a type-II direct bandgap, which remains stable within a strain range of −6 to 6%. Furthermore, we delve into the alterations in band edge positions in single-walled nanotubes induced by curvature-driven flexoelectric effects and circumferential tensile strain. In coaxial heterotubes, the transfer of electrons between the inner and outer tubes forms a cylindrical capacitor-like structure. Incorporating the inherent flexoelectric voltage in single-walled nanotubes, we have derived a functional relationship between the counteracting voltage (V_hyb) and their diameter. Finally, the system was explored for its strong light absorption capabilities with absorption levels up to 10⁵, and it was found that strain can effectively modulate the range of light absorption. The findings of this research contribute to new insights and theoretical foundations for the development of novel one-dimensional (1D) van der Waals (vdW) optoelectronic devices.

中文翻译：

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探索挠曲电效应在一维 MoS2/磷化硼纳米管异质结构中能带调制中的作用


设计和发现卓越的 II 型频带对准对于推进光电器件技术至关重要。在这里，我们采用第一性原理计算来研究单层 MoS₂、磷化硼 （BP） 和 MoS₂/BP 异质结构在卷入纳米管前后的能带边缘演变。我们的研究结果表明，本征的 MoS₂/BP 垂直异质结构表现出 II 型直接带隙，但这一特征在应变下并不稳健。对于 MoS₂/BP 同轴异质管，带隙类型受手性和直径的影响。具体来说，当直径在锯齿形手性下超过 19 Å 时，系统经历从 I 型直接带隙到 II 型直接带隙的转变，在 −6% 至 6% 的应变范围内保持稳定。此外，我们深入研究了曲率驱动的挠曲电效应和周向拉伸应变引起的单壁纳米管带边缘位置的变化。在同轴异质管中，电子在内管和外管之间的转移形成圆柱形电容器状结构。将固有的弯曲电压结合到单壁纳米管中，我们得出了抵消电压 （V_hyb） 与其直径之间的函数关系。最后，探索了该系统具有很强的光吸收能力，吸收水平高达 10⁵，发现应变可以有效调节光吸收范围。这项研究的结果为开发新型一维 （1D） 范德华 （vdW） 光电器件提供了新的见解和理论基础。