September 2021
Spotlight Summary by Beat Ruhstaller
Analysis and optimization of light outcoupling in OLEDs with external hierarchical textures
Focused on the quest for always increasing the out-coupling efficiency of organic LEDs (OLEDs) for lighting applications, this paper introduces original hierarchical structures embossed into plastic foils that are laminated on OLED substrates. These foils have structures with a simultaneously small and large periodicity, providing a large design freedom for optimizing the light output. Thorough experimental characterization is carried out to quantify the out-coupling enhancement, which turns out to be a challenge since finite-size pixel and substrate effects influence the measurement results. In that context, the employed multi-scale optical out-coupling model proves handy. It combines the wave-optical aspects of the thin film OLED stack and the ray-optical light propagation in the out-coupling structures, thereby being able to reproduce the efficiency reductions observed in the finite-size OLED samples.
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Article Information
Analysis and optimization of light outcoupling in OLEDs with external hierarchical textures
Milan Kovačič, Dinara Samigullina, Felix Bouchard, Janez Krč, Benjamin Lipovšek, Marcos Soldera, Andrés Fabián Lasagni, Sebastian Reineke, and Marko Topič
Opt. Express 29(15) 23701-23716 (2021) View: Abstract | HTML | PDF