Gong L J, Shi H L, Yang J, Han Q Z, Ren Y H, He S Y, Zhao Y H, Jiang Z T
School of Physics, Beijing Institute of Technology, Beijing 100081, China.
Shandong Graphenjoy Advanced Material Co. Ltd, Dezhou 253072, China.
Phys Chem Chem Phys. 2023 Aug 23;25(33):22487-22496. doi: 10.1039/d3cp02848h.
Based on first-principles density functional theory and nonequilibrium Green's function, we study the electronic band structures, the electronic transport properties, and the optical absorption of bilayer blue phosphorene nanoribbons (BPNRs). Both bilayer armchair BPNRs (a-BPNRs) and zigzag BPNRs (z-BPNRs) behave as semiconductors in the narrow nanoribbon case and metals in the wide nanoribbon case, sharply different from their monolayer counterparts where the monolayer a-BPNRs (z-BPNRs) are always semiconducting (metallic). This indicates that interlayer couplings or the increasing layer number may induce the switching of the conductivity of the monolayer BPNRs, which is absent in graphene and phosphorene nanoribbons. Furthermore, we explore the edge states of the energy bands near Fermi energy, and find that there are almost no pure edge-state band branches in the bilayer BPNRs, which can be attributed to the interlayer couplings between the edge-states in one layer and the bulk-states in the other. Consequently, the resulting complex band structures cannot be directly analyzed any more in the framework of the two-body coupling picture just according to the simple band structures of the monolayer BPNRs. Finally, we present the current-voltage characteristics and the optical absorption of the bilayer a-BPNRs and z-BPNRs. The influences of the nanoribbon width and the interlayer couplings on the current and the anisotropic optical absorption can be understood based on the complex energy band structures. This research should be an important reference of extending the field of BPNRs from the monolayer to the bilayer case, and deepen the understanding of the difference between the monolayer and bilayer nanoribbons in different materials.
基于第一性原理密度泛函理论和非平衡格林函数，我们研究了双层蓝色磷烯纳米带（BPNRs）的电子能带结构、电子输运性质和光吸收。双层扶手椅型BPNRs（a-BPNRs）和锯齿型BPNRs（z-BPNRs）在窄纳米带情况下表现为半导体，在宽纳米带情况下表现为金属，这与它们的单层对应物截然不同，单层a-BPNRs（z-BPNRs）总是半导体（金属）。这表明层间耦合或层数增加可能会导致单层BPNRs电导率的转变，而这在石墨烯和磷烯纳米带中是不存在的。此外，我们探索了费米能级附近能带的边缘态，发现双层BPNRs中几乎没有纯边缘态能带分支，这可归因于一层中的边缘态与另一层中的体态之间的层间耦合。因此，在仅根据单层BPNRs的简单能带结构的两体耦合框架下，无法再直接分析由此产生的复杂能带结构。最后，我们给出了双层a-BPNRs和z-BPNRs的电流-电压特性和光吸收。基于复杂的能带结构，可以理解纳米带宽度和层间耦合对电流和各向异性光吸收的影响。本研究应为将BPNRs领域从单层扩展到双层情况提供重要参考，并加深对不同材料中单层和双层纳米带差异的理解。
