Excitons in bent black phosphorus nanoribbons: multiple excitonic funnels
Excitons in bent black phosphorus nanoribbons: multiple excitonic funnels
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DOI：
10.1016/j.mtadv.2020.100096
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
J. Sun;X. Li;C. Ullrich;J. Yang
中科院分区：
文献类型：
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作者：
J. Sun;X. Li;C. Ullrich;J. Yang
准一维纳米带(NRs)是具有高器件密度的柔性光电子学的重要候选材料。纳米材料的光学性质受到激子的强烈影响，研究激子在应变下的行为对柔性器件具有重要意义。在这项工作中，我们用密度泛函理论和多体格林函数方法研究了弯曲的黑磷(BP)近红外光谱的电子和激子性质。我们发现，非均匀应变场不仅影响第一激子能量，从而影响光学带隙，而且还影响激子的空间分布。特别是，激子漏斗可以出现在弯曲的黑色磷纳米带(BPNR)中，它驱动较高能量的激子向较低能量位置移动。漏斗可以通过应变场的强度和符号(压缩到拉伸)来有效地调节。另一个关键因素是各向异性：扶手椅BPNR的漏斗效应比之字形BPNR更加明显。此外，我们还发现二维单分子膜BP中的激子漏斗效应与多层BP膜中的不同。
Quasi-one-dimensional nanoribbons (NRs) are promising candidate materials for flexible optoelectronics with high device density. The optical properties of nanomaterials are strongly influenced by excitons, and it is important for flexible devices to explore how excitons behave under strain. In this work, we investigate the electronic and excitonic properties of bent black phosphorus (BP) NRs via density-functional theory and many-body Green's function methods. We find that inhomogeneous strain fields affect not only the first excitonic energy and thus the optical gap, but also the spatial distribution of the excitons. In particular, excitonic funnels can occur in bent black phosphorus nanoribbons (BPNRs), which drive higher-energy excitons toward lower energy locations. The funnels can be effectively tuned by the intensity and sign (compressed to tensile) of the strain field. Another critical factor is anisotropy: the funnel effect is much more pronounced in armchair BPNRs than in zigzag BPNRs. In addition, we find that the excitonic funnel effect in two-dimensional monolayer BP differs from that in multilayer BP films.