Efficient waveguide mode extraction in white organic light emitting diodes using ITO-anodes with integrated MgF₂-columns.

We report a simple approach to enhance the out-coupling efficiency in white organic light emitting diodes (WOLEDs). By incorporating MgF₂-columns into the ITO-anode and optimizing of their geometry, an overall efficiency enhancement of up to 38% is achieved. In addition, the structuring of the anode does not lead to a change in the electrical behaviour of the devices. As evidenced by goniometric measurements, the angular emission characteristics of the WOLEDs remain unchanged. Simulations, performed with the T-matrix method, reveal the effect of the enhanced outcoupling efficiency of this approach.