A study on the applications of nanostructures fabricated by using mass transport phenomena of azobenzene polymer

Abstract

In the last decade, nanotechnology has gained remarkable attention because of new properties and function of matter at the nanoscale. So, there are an increasing interest and demand to fabrication methods of nanostructures. Although many methods to make nanostructures have been proposed, most previous methods usually require complicated and time-consuming techniques. Herein, we demonstrated a much simpler, faster and cheaper method for fabricating nanostructures using self-structuring under one-beam irradiation onto the azobenzene polymer (abbreviated as azopolymer) thin film. One-beam irradiation of the azopolymer thin film leads to the generation of nanodome arrays in hexagonal lattice. The features of nanodome arrays such as modulation height, width gradually increased with the irradiation time. These photoinduced nanodome arrays on azopolymer films are used directly to mold PDMS, and the PDMS molds are then transferred to the UV-photocrosslinkable layer to imprint nanodome arrays. By using this method, we can fabricate moth-eye antireflection coatings. The fabricated moth-eye antireflection coatings show improved transmission (average 3 ~ 4%) in the spectral ranges from 500 nm to 1100 nm at normal incidence. Moreover, we demonstrate plasmonic nanodome arrays which is fabricated by gold deposition onto the nanodome arrays on azopolymer film. The plasmonic arrays can be useful for the surface-enhanced Raman scattering (SERS). We believe that this fabrication method of moth-eye antireflection coatings and SERS substrates was easier and cheaper than any other method and will open path towards practical application of nanostructures.