Department of Materials Science and Engineering, National Taiwan University, Taipei, Taiwan.
ACS Nano. 2010 Mar 23;4(3):1327-36. doi: 10.1021/nn901910h.
In this study, we prepared carbon nanotube (CNT) forests exhibiting two types of optical properties: so-called "darkest materials" and films displaying iridescence phenomena. The darkest materials, comprising vertically aligned CNT (VA-CNT) forests, displayed extremely low reflections as a result of the rough surface and the trapping of light in the CNT forests. The lengths of the CNTs in the CNT forests had a strong influence on whether the light transmitted through the CNT forest or reflected from the substrate. From an investigation of the limitations of the darkest materials of CNT forests, we prepared CNT surfaces running the gamut from dark materials to iridescent. To study iridescence phenomena, we prepared two kinds of patterns of CNT forests on flexible polycarbonate substrates: CNTs arrayed in hexagonal-hole patterns and broccoli-like CNTs, the latter formed through a combination of inverse nanosphere lithography (INSL) and a poisoned-catalyst mechanism. In the patterned CNT forests, even though the refractive index difference between the CNT film and air was extremely low and even though the CNTs could trap the incident light, the iridescence phenomenon remained, inducing colorful images from the CNT films.
在这项研究中，我们制备了具有两种光学特性的碳纳米管（CNT）森林：所谓的“最黑材料”和显示虹彩现象的薄膜。最黑材料由垂直排列的 CNT（VA-CNT）森林组成，由于粗糙的表面和 CNT 森林中光的捕获，显示出极低的反射率。 CNT 森林中 CNT 的长度强烈影响光是透过 CNT 森林还是从基底反射。从对 CNT 森林最黑材料的局限性的研究中，我们制备了 CNT 表面，从黑暗材料到虹彩材料都有涉及。为了研究虹彩现象，我们在柔性聚碳酸酯基底上制备了两种 CNT 森林图案：六边形孔图案排列的 CNT 和花椰菜状 CNT，后者通过逆纳米球光刻（INSL）和中毒催化剂机制的组合形成。在图案化 CNT 森林中，尽管 CNT 薄膜和空气之间的折射率差异非常低，并且 CNT 可以捕获入射光，但虹彩现象仍然存在，从 CNT 薄膜中诱导出彩色图像。
