Scattering quantified: Evaluation of corrugation induced outcoupling concepts in organic light-emitting diodes

Organic light-emitting diodes (OLEDs) currently suffer mostly from only moderate outcoupling efficiencies, calling for many different photonic strategies to increase the share of extracted photons. The quantification of concepts relying on scattering based on periodic or random structures proves complicated and often deserves more attention. To evaluate light extraction methods of OLEDs, we define a procedure leading to a quantifiable extraction efficiency eta(EE) which can be calculated for top- or bottom-emitting OLEDs comprising external as well as internal outcoupling structures. Hence, the extraction efficiency allows to evaluate scattering approaches independently from the employed OLED system. A systematic study of 1D periodically corrugated red top-emitting OLEDs reveals the origin of a moderate enhancement due to an extraction efficiency of eta(EE) = 14%. Furthermore, our work provides recommendations how OLEDs with periodic corrugations should be characterized.