Preparation of Moth-Eye Structures By Nanoimprinting Using Anodic Porous Alumina Molds

Abstract

Moth-eye structures composed of an ordered array of tapered pillars have attracted increasing interest owing to their application such as displays, lenses and solar cells. A large number of methods have been reported for the preparation of moth-eye structures. Among them, nanoimprinting is a promising method for the high-throughput preparation of moth-eye structures with large sample areas. In our previous works, we have reported that an ordered anodic porous alumina can be used for a nanoimprinting mold to prepare seamless moth-eye surfaces with large sample areas [1,2]. In this process, the moth-eye structures with optimized antireflection properties was obtained by adjusting the preparation conditions of porous alumina molds. One problem currently limiting the practical use of moth-eye structures is their low durability. This problem originates from the fine, high-aspect geometrical features of moth-eye structures. Improved durability is essential for practical application of moth-eye structures as antireflection surfaces. In the present report, we describe the preparation of renewable antireflection surfaces by nanoimprinting using an anodic porous alumina mold. Renewable antireflection surfaces were formed by the lamination of polymer thin films with moth-eye structured surfaces [3]. Thin-film lamination was performed using a photocurable monomer as an adhesive. A renewed low-reflectance moth-eye structured surface could be exposed by peeling the uppermost film from the sample. Each exposed surface with moth-eye structure successfully lowered the reflection of incident light. The obtained renewable antireflection surfaces are expected to be applicable to several types of optical devices requiring high durability, such as the surface panels of displays. T. Yanagishita, K. Nishio, and H. Masuda, Appl. Phys. Express, 2, 022001 (2009).T. Yanagishita, T. Hidaka, M. Suzuki, and Hideki Masuda, J. Vac. Sci. Technol. B, 34, 021804 (2016).T. Yanagishita, T. Kondo, and H. Masuda, J. Vac. Sci. Technol. B, 36, 031802 (2018).