Abstract: A composition for use in forming low-refractive-index layers includes a siloxane polymer, a porogen, and a curing catalyst that is different from the porogen. The composition can be processed at low temperatures of less than about 125° C. (e.g., about 70-90° C.) to crosslink the polymer. The crosslinked material can be exposed to a developer (e.g., acetone) to remove the porogen, thus forming a low-refractive-index film (e.g., less than about 1.3). A method of forming a nanoporous structure includes applying a composition including a siloxane polymer and a porogen to a substrate. The composition optionally includes a curing catalyst different from the porogen. The siloxane polymer is crosslinked and then contacted with a developer so as to remove the porogen and form pores in the crosslinked composition to yield the nanoporous structure.

Abstract: Materials that are processable as spin coated films with a refractive index of less than about 1.25 are presented. These compositions include metal organic frameworks in a solvent system, with the MOFs including a metal or metal cluster (e.g., zirconium oxide) having organic linkers (e.g., maleic acid, benzene dicarboxylic acid) and optional endcaps to alter pore size, compositional stability, steric, and other properties of the material. The formed films are processable at low temperatures, thus allowing them to be processed on plastics. The provided materials find use in, for example, silicon photonics, augmented reality applications, virtual reality (VR) applications, CMOS image sensors, and micro-OLED applications.