Poor light extraction efficiency from OLEDs is among the leading problems facing the science and commercialization of OLEDs. The light outcoupling ~1/2n2, where n is the refractive index of the organic emitting layer, and is only 17-20% for planar OLEDs. The remaining light is waveguided in the organic +ITO layers (>30%), waveguided in the substrate, or lost to plasmonic excitation in the cathode that can be very severe (>40%) for thin ETLs.
To enhance outcoupling we investigate the light emission from periodically corrugated OLEDs where the OLED stack is grown conformally on a periodic textured substrate . The corrugation diffracts wave-guided modes to the air cone, thereby increasing outcoupling, but no simulations have predicted enhancements or optimal corrugations. We utilize rigorous scattering matrix simulations solving Maxwell’s equations in Fourier space, for all polarizations. We find the corrugated OLEDS display a remarkable light outcoupling of 60-70%, approaching the targeted value of 70% in the solid-state lighting road-map. We find optimal corrugation pitch of 0.75-3 microns with only a small roll off for larger pitch. The optimal corrugation heights exceed 150 nm. There is a marked decrease in plasmonic losses. Corrugations induce strong diffraction of light into the air cone. We also find that adding a microlens on the air-substrate interface can increase by a further ~5-10%. We compare simulations with experimental results .Supported by DOE-EERE
 C. Hippola et al, Adv. Optical Materials 6, 1701244 (2018).