Stability and Performance of Organic-Inorganic Thin Films on Polymer Substrates
March 27, 2017 12:00 am
Polymer is replacing glass at an increasing rate in uses ranging from ophthalmic applications to electronic devices and displays. In the case of optical interference filters on plastic substrates such as antireflective coatings, the performance of the device is limited by the coating-substrate compatibility; for example, thermal expansion coefficient of the substrate is about 100 times that of glass. Significantly improved resistance to temperature and humidity variation and higher elastic recovery of organic-inorganic SiO2 and ZrO2 coatings compared to their inorganic counterparts are demonstrated. Organic-inorganic coatings prepared by ion-beam-assisted chemical vapor deposition (IBACVD) show a higher thermal expansion (10-5 K-1) close to that of polymer substrates (10-4 K-1 for CR-39) as well as a relatively high hardness/elastic modulus (H/E) ratio (up to 0.16). Both individual organic-inorganic layers and complete antireflective stacks exhibit a higher durability following accelerated environmental tests including exposure to high temperature/high humidity, ultraviolet (UV) and solar radiation, and a saline solution.