Improvement in the light outcoupling efficiency of organic light-emitting diodes using a hemispherical lens and a multipatterned one-dimensional photonic crystal fabricated by autocloning

The outcoupling efficiency of organic light-emitting diodes was improved using a photonic crystal fabricated by autocloning, which has potential advantages for mass production. By using layer thicknesses optimized by optical simulations, the experimental external quantum efficiency of a device with the photonic crystal and a hemispherical lens was 43.4%, which is 2.13 times that of a device on a flat substrate without the lens. Comparisons with the simulated distributions of the light modes in the devices show that the photonic crystal reduces the light loss from the waveguide and evanescent modes. The emission pattern was independent of substrate rotation.