Large-Scale Moth-Eye-Structured Roll Mold Fabrication Using Sputtered Glassy Carbon Layer and Transferred Moth-Eye Film Characterization

Currently, there is high demand for the development of a highly mass-producible technology for manufacturing moth-eye-structured films with an antireflection function. Conventional moth-eye-structured films have been produced by roll-to-roll (RTR) ultraviolet nanoimprint lithography (UV-NIL) using porous alumina, but the process of manufacturing the roll mold with aluminum is both complicated and time-consuming. To solve this problem, we proposed a sputtering process for forming a thin film of glassy carbon on a roll substrate and fabricated a moth-eye structure through the irradiation of oxygen plasma. A glassy carbon (GC) moth-eye-structure roll mold with a uniform reflectance of less than 0.1% over a length of 1560 mm was fabricated following this method. In addition, a superhydrophobic moth-eye-structured film was produced by RTR UV-NIL using the proposed roll mold, which exhibited a reflectance of 0.1%. In this study, a moth-eye-structure roll using porous alumina was compared with a film transferred from it. The GC moth-eye-structure roll mold was found to be superior in terms of antireflection, water repellency, and productivity. When the proposed large-area GC moth-eye-structured film was applied to window glass, significant anti-reflection and water-repellent functionalities were obtained.

Automated summary

There is a high demand for a highly mass-producible technology for manufacturing moth-eye-structured films with antireflection function. Conventional films are made using roll-to-roll ultraviolet nanoimprint lithography with aluminum, but the process is complicated and time-consuming. To solve this problem, a sputtering process for forming a thin film of glassy carbon on a roll substrate was proposed, which resulted in a moth-eye structure through oxygen plasma irradiation. The glassy carbon roll mold showed superior antireflection, water repellency, and productivity compared to the moth-eye-structured film made with porous alumina.