The efficiency of organic light emitting diodes is known to be optically limited by different light trapping effects within the device structure. Several approaches have been suggested to enhance the transfer of radiation generated within the device into free space radiation. These approaches include nanoscale wave optical effects to optimize the stratified active media or to diffract guided modes travelling within the active system, as well as refractive or scattering elements to derange total internal reflection within the substrate. This paper deals with substrate emitting devices, where nano- or microscale structures enforce a 'recycling' of light that originally would have been trapped within the system. An approach enabling for a combined treatment of ray-optical and thin-film-optimization is introduced and applied to the optimization of an example system. The results indicate an improved system design due to that complex optimization© (2007) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.