Empirical formulation of broadband complex refractive index spectra of single-chirality carbon nanotube assembly
Empirical formulation of broadband complex refractive index spectra of single-chirality carbon nanotube assembly
复制标题
DOI：
10.1515/nanoph-2021-0728
复制
发表时间：
2022-01
期刊：
影响因子：
7.5
通讯作者：
Taishi Nishihara;Akira Takakura;Masafumi Shimasaki;K. Matsuda;Takeshi Tanaka;H. Kataura;Y. Miyauchi
中科院分区：
文献类型：
--
作者：
Taishi Nishihara;Akira Takakura;Masafumi Shimasaki;K. Matsuda;Takeshi Tanaka;H. Kataura;Y. Miyauchi
摘要具有特定手性结构的单壁碳纳米管组装体是一种很有前途的未来光功能材料，因为它们具有由准一维激子的尖锐光学共振产生的强轻物质耦合。它们的强光学共振位于红外到可见光波长区域，可以通过它们的手性来选择，并且这种选择性承诺了广泛的应用，包括光子和热光器件。然而，单手性碳纳米管组装体的宽带复杂光谱在文献中很少，这阻碍了研究人员和工程师使用它们设计设备。在这里，我们通过实验测定了单手性碳纳米管组装体的宽带复折射率谱。自支撑碳纳米管膜和放置在蓝宝石衬底上的那些通过使用凝胶色谱分离方法制备的纳米管溶液的过滤来制造。在中红外到可见光波长区域测量透射和反射光谱，并确定纳米管组件的复折射率作为光子能量的函数。体积密度为1 g cm-3的纳米管膜在第一子带激子共振下的折射率的真实的和虚部分别被确定为约2.7-3.6和1.3i-2.4i。我们提出了一个经验公式，唯象地描述了各种单手性纳米管膜的复折射率谱，这可以促进使用碳纳米管作为材料的光子器件的设计。
Abstract Assemblies of single-walled carbon nanotubes with a specific chiral structure are promising future optofunctional materials because of their strong light–matter coupling arising from sharp optical resonances of quasi-one-dimensional excitons. Their strong optical resonances, which lie in the infrared-to-visible wavelength region, can be selected by their chiralities, and this selectivity promises a wide range of applications including photonic and thermo-optic devices. However, the broadband complex optical spectra of single-chirality carbon nanotube assemblies are scarce in the literature, which has prevented researchers and engineers from designing devices using them. Here, we experimentally determine broadband complex refractive index spectra of single-chirality carbon nanotube assemblies. Free-standing carbon nanotube membranes and those placed on sapphire substrates were fabricated via filtration of the nanotube solution prepared by the separation method using gel chromatography. Transmission and reflection spectra were measured in the mid-infrared to visible wavelength region, and the complex refractive indices of nanotube assemblies were determined as a function of photon energy. The real and imaginary parts of the refractive indices of the nanotube membrane with a bulk density of 1 g cm−3 at the first subband exciton resonance were determined to be approximately 2.7–3.6 and 1.3i–2.4i, respectively. We propose an empirical formula that phenomenologically describes the complex refractive index spectra of various single-chirality nanotube membranes, which can facilitate the design of photonic devices using carbon nanotubes as the material.