Outcoupling Enhancement of OLEDs With a Randomly Distributed ITO Pattern Fabricated by Maskless Wet Etching Method

To outcouple the photons trapped in OLEDs, the effect of a rough ITO surface is investigated. The rough surface is obtained by simple maskless wet etching producing a randomly distributed nano-pattern. The power efficiency is improved by 54%, and further enhanced to 83% with a microlens array. As the pattern located between the organic layer and the ITO anode overlaps strongly with the guided mode, it results in a strong scattering rather than the diffraction, so that the device produces no angular dependence or spectral shift. Electrical property and the lifetime of the device are not affected by the etched ITO.