High-refractive-index polymers with high transparency

μThe emergence of adaptive and compact optical and optoelectronic devices, including flexible electronics, wearable displays, and solar panels, has necessitated the use of flexible and fracture-resistant substrates. High refractive index (HRI) polymeric coatings are being explored as promising alternatives to traditional inorganic thin films. In this study, three pure organic platforms were developed that offer tunable refractive indices (1.6 to 1.8 at 550 nm) and high light transmission (>98% at 400 nm for a 2-μm film). These HRI polymers demonstrate excellent compatibility with common processing solvents such as PGMEA, PGME, and acetone, as well as high thermal resistance with a Td of 300-370°C. Furthermore, an extended high-temperature baking study revealed the thermal and optical stability of our HRI polymer coatings, with less than 5% film thickness loss and less than 1% changes in optical properties. Additionally, we have developed photo-imageable formulations based on these HRI polymers, which can yield well-defined small features (<5 Θm) through i-line exposure.