25 August 2017 Inkjet-printed polymer-based scattering layers for enhanced light outcoupling from top-emitting organic light-emitting diodes
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Abstract
High refractive index polymer-based scattering layers used as internal light extraction layers are a promising low-cost approach to enhance the luminous efficacy of organic light-emitting diodes (OLEDs). In order to avoid damaging of the OLED layers a structured and contactless deposition method for the polymer-based scattering layers is required. For enhanced lifetime of the devices the water diffusion through the scattering layer has to be eliminated by a structured patterning technique. Inkjet printing offers both a contactless and structured deposition. In this study we evaluate inkjet printing of nanocomposite polymer-based scattering layers for OLEDs. A detailed view on the material and process development is given. This involves an optimization of ink formulation, printing parameters as well as layer formation. The resulting haze values of the scattering layers at 550 nm vary between 40% and 90% for different layer thicknesses. The gain in external quantum efficacy of top-emitting OLEDs induced by light scattering compared to reference devices peaks at a factor of 2.3. The obtained results are discussed and verified by an optical volume scattering simulation model which will be presented in full detail. Also a parameter variation study and its impact on extraction efficiency will be shown.
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Armin Heinrichsdobler, Armin Heinrichsdobler, Manuel Engelmayer, Manuel Engelmayer, Daniel Riedel, Daniel Riedel, Christoph J. Brabec, Christoph J. Brabec, Thomas Wehlus, Thomas Wehlus, } "Inkjet-printed polymer-based scattering layers for enhanced light outcoupling from top-emitting organic light-emitting diodes", Proc. SPIE 10362, Organic Light Emitting Materials and Devices XXI, 103622B (25 August 2017); doi: 10.1117/12.2272976; https://doi.org/10.1117/12.2272976
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