Duan Yulong, Rahmanudin Aiman, Chen Shangzhi, Kim Nara, Mohammadi Mohsen, Tybrandt Klas, Jonsson Magnus P
Laboratory of Organic Electronics, Department of Science and Technology (ITN), Linköping University, Norrköping, SE-601 74, Sweden.
Adv Mater. 2023 Dec;35(51):e2303949. doi: 10.1002/adma.202303949. Epub 2023 Nov 12.
A wide range of nanophotonic applications rely on polarization-dependent plasmonic resonances, which usually requires metallic nanostructures that have anisotropic shape. This work demonstrates polarization-dependent plasmonic resonances instead by breaking symmetry via material permittivity. The study shows that molecular alignment of a conducting polymer can lead to a material with polarization-dependent plasma frequency and corresponding in-plane hyperbolic permittivity region. This result is not expected based only on anisotropic charge mobility but implies that also the effective mass of the charge carriers becomes anisotropic upon polymer alignment. This unique feature is used to demonstrate circularly symmetric nanoantennas that provide different plasmonic resonances parallel and perpendicular to the alignment direction. The nanoantennas are further tuneable via the redox state of the polymer. Importantly, polymer alignment could blueshift the plasma wavelength and resonances by several hundreds of nanometers, forming a novel approach toward reaching the ultimate goal of redox-tunable conducting polymer nanoantennas for visible light.
广泛的纳米光子学应用依赖于偏振相关的等离子体共振，这通常需要具有各向异性形状的金属纳米结构。这项工作通过材料介电常数打破对称性，转而展示了偏振相关的等离子体共振。该研究表明，导电聚合物的分子排列可以导致一种具有偏振相关等离子体频率和相应面内双曲线介电常数区域的材料。仅基于各向异性的电荷迁移率，这一结果是无法预期的，但这意味着在聚合物排列时，电荷载流子的有效质量也会变得各向异性。这一独特特性被用于展示圆形对称的纳米天线，其在平行和垂直于排列方向上提供不同的等离子体共振。这些纳米天线还可以通过聚合物的氧化还原状态进一步调谐。重要的是，聚合物排列可以使等离子体波长和共振蓝移数百纳米，为实现用于可见光的氧化还原可调谐导电聚合物纳米天线这一最终目标形成了一种新方法。
