Advanced Materials and BioEngineering Research Centre (AMBER) & CRANN, Trinity College Dublin, The University of Dublin , Dublin 2, Ireland.
Department of Chemistry, University College Cork , Cork, T12 YN60, Ireland.
Nano Lett. 2017 May 10;17(5):2973-2978. doi: 10.1021/acs.nanolett.7b00226. Epub 2017 Apr 7.
Nanostructured surfaces are common in nature and exhibit properties such as antireflectivity (moth eyes), self-cleaning (lotus leaf), iridescent colors (butterfly wings), and water harvesting (desert beetles). We now understand such properties and can mimic some of these natural structures in the laboratory. However, these synthetic structures are limited since they are not easily mass produced over large areas due to the limited scalability of current technologies such as UV-lithography, the high cost of infrastructure, and the difficulty in nonplanar surfaces. Here, we report a solution process based on block copolymer (BCP) self-assembly to fabricate subwavelength structures on large areas of optical and curved surfaces with feature sizes and spacings designed to efficiently scatter visible light. Si nanopillars (SiNPs) with diameters of ∼115 ± 19 nm, periodicity of 180 ± 18 nm, and aspect ratio of 2-15 show a reduction in reflectivity by a factor of 100, <0.16% between 400 and 900 nm at an angle of incidence of 30°. Significantly, the reflectivity remains below 1.75% up to incident angles of 75°. Modeling the efficiency of a SiNP PV suggests a 24.6% increase in efficiency, representing a 3.52% (absolute) or 16.7% (relative) increase in electrical energy output from the PV system compared to AR-coated device.
纳米结构表面在自然界中很常见，具有抗反射（蛾眼）、自清洁（荷叶）、彩虹色（蝴蝶翅膀）和集水（沙漠甲虫）等特性。我们现在了解这些特性，并可以在实验室中模拟一些这些自然结构。然而，由于当前技术（如紫外光刻）的可扩展性有限、基础设施成本高以及在非平面表面上的困难，这些合成结构的应用受到限制，因此难以在大面积上生产。在这里，我们报告了一种基于嵌段共聚物（BCP）自组装的溶液处理方法，用于在大面积光学和曲面上制造亚波长结构，其特征尺寸和间距设计用于有效地散射可见光。直径约为 115 ± 19 nm、周期为 180 ± 18 nm、纵横比为 2-15 的 Si 纳米柱（SiNPs）在入射角为 30°时，反射率降低了 100 倍，在 400nm 至 900nm 之间的反射率<0.16%。值得注意的是，在入射角为 75°时，反射率仍保持在 1.75%以下。对 SiNP PV 的效率进行建模表明，效率提高了 24.6%，与具有抗反射涂层的器件相比，PV 系统的电能输出增加了 3.52%（绝对）或 16.7%（相对）。
