US Patent 8659221 OLED light extraction film with multi-periodic zones of nanostructures

A light extraction film having multi-periodic zones of engineered nanostructures. The light extraction film includes a flexible substrate, a layer of low index engineered nanostructures applied to the substrate, and a high index backfill layer applied over the nanostructures. The multi-periodic zones include a repeating zone of the nanostructures having multi-periodic characteristics. The repeating zone includes first and second sets of nanostructures having different periodic pitches. The multi-periodic zones can be used to enhance the light output and tune the angular luminosity of organic light emitting diode devices.