Polyimide moth-eye nanostructures formed by oxygen ion beam etching for anti-reflection layers

Here, we report the use of a simple oxygen ion-beam etching process to fabricate polyimide moth-eye-like nanostructures as anti-reflection layers. The etching process formed moth-eye nanostructures directly onto polyimide layer surfaces that covered both flat and curved surfaces. Notably, this approach removed the need for a masking process, which reduced the number of separate fabrication steps compared with conventional methods that require repeated moth-eye etching on flat and hard materials, such as ceramics and curve surfaces. The proposed method formed moth-eyes through a single step etching process on both flat and curved substrates. The moth-eyes had an average height and pitch of approximately 700 and 100 nm, respectively, on a synthesized polyimide layer on both flat and curved substrates. The reflectivity of the fabricated polyimide moth-eye was as low as 0.2%-0.48%. The utility of the method to form anti-reflection layers in practical optical devices is also confirmed.