Stability and performance of organic-inorganic thin films on polymer substrates

Abstract

The use of polymer instead of glass is increasingly frequent, ranging from ophthalmic applications to electronic devices, displays and others. In the case of optical interference filters on plastic substrates (e.g., antireflective coatings) the performance of the device is limited by the coating-substrate compatibility (e.g., thermal expansion coefficient of the substrate about 100 times that of glass). In the present work, we demonstrate significantly improved resistance to temperature and humidity variation and higher elastic recovery of organic-inorganic SiO2 and ZrO2 coatings compared to their inorganic counterparts. Specifically, organic-inorganic coatings prepared by ion beam assisted chemical vapour deposition (IBACVD) show a higher thermal expansion (10−5K−1) close to that of polymer substrates (10−4K−1 for CR-39) and a relatively high H/E ratio (as up to 0.16). We show that both individual organic-inorganic layers as well as complete antireflective stacks exhibit a higher durability following accelerated environmental tests including exposure to high temperature/high humidity, UV and solar radiation, as well as a saline solution.