Micro optical pattern shaping for tailored light emission from organic LEDs

The application of large area OLEDs for lighting and signage purposes potentially requires essential changes of the common Lambert-like emission pattern. We demonstrate an array based micro optical approach for pattern shaping of area light sources based on distorted Fourier imaging of an aperture array with a micro lens array. Narrow angular emission patterns of ± 35° and ± 18° FWHM obtained experimentally demonstrate the pattern shaping with low stray light levels. The internal recycling of initially rejected photons yields intensity enhancements exceeding a factor two in forward direction that is still well below the theoretical limits due to limited reflectivity.