Ultra high vacuum operated prototypical organic light emitting diodes have been investigated by using chemically sensitive x-ray photoelectron microscopy. The mechanism of dark spot formation and degradation of organic light emitting devices have been imaged and spectroscopically measured. The morphology and the chemical composition of the Al cathode reveal the formation of volcano like defects as a result of local micro-explosions. The chemical maps and
micro-spot spectra identify a release of volatile In-, Sn- and C-containing species, including metallic In, supporting the evidence that the degradation process is driven by local decomposition of the ITO/organic interface.
An OLED device suitable for automobile ceiling lights has been designed, fabricated and evaluated. The OLED structure is fabricated on a thin (120 µm), flexible polymer foil with integrated micro-optics to achieve customized beam shaping in the far field. A pixelated OLED structure matched to a patch-pad microlens matrix was used to convert the OLED Lambertian emission into a Gaussian-shaped illumination beam. Both refractive and diffractive microlenses were investigated. The integrated micro-optics OLED architecture reduces light losses due to waveguiding effects and effectively increases the light extraction by up to 70%.