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Efficient out-coupling light extraction and optical beam shaping have been combined to form an integrated, flexible illuminator that is based on organic light-emitting diodes (OLEDs). Spherical refractive microlenses were replicated by a cost-effective UV-casting technique onto a plastic foil to achieve the customized Gaussian distribution of the electroluminescence of an OLED pixel (50 μm) matrix. The fabricated optical device, namely a ceiling light illuminator, shows an improvement of 70% in the out-coupled emission measured in the far field. The result corresponds to the theoretical prediction for isotropic emitting sources. [ABSTRACT FROM AUTHOR]

Using chemically sensitive x-ray photoelectron microscopy, we investigate the mechanism of dark-spot formation and degradation of organic light-emitting devices. The morphological and chemical evolution of the Al cathode surface under operation conditions reveals the formation of “domelike” structures, followed by local disruptions of the cathode, exposing microareas of the underlying indium tin oxide anode. The chemical maps and microspot spectra identify a release of volatile In-, Sn-, and C-containing species, including metallic In, which is clear evidence that the degradation is driven by local decomposition of the anode/organic interface. [ABSTRACT FROM AUTHOR]