Simulation based optimization of light-outcoupling in organic light-emitting diodes

The internal quantum efficiency of organic light-emitting diodes (OLEDs) can reach values close to 100% if phosphorescent emitters to harvest triplet excitons are used, however, the fraction of light that is actually leaving the device is considerably less. In this work we use numerical simulations to optimize light outcoupling from different OLED stacks. First, we change the distance of the emission zone to the cathode, which minimizes the excitation of surface plasmons. Then the influence of different dipole orientation of the emitter material on the light outcoupling is studied. Finally, a metal-free, transparent OLED stack reported by Meyer et al.,1 where no plasmons can be excited, is investigated for improved outcoupling efficiency.