Enhancing outcoupling efficiency of indium-tin-oxide-free organic light-emitting diodes via nanostructured high index layers

Riedel, Boris; Hauss, Julian; Geyer, Ulf; Guetlein, Johanna; Lemmer, Uli; Gerken, Martina
June 2010
Applied Physics Letters;6/14/2010, Vol. 96 Issue 24, p243302
Academic Journal
We fabricated organic light-emitting diodes with one-dimensional Bragg gratings as light extraction elements for substrate and waveguide modes. A Ta2O5 layer was introduced to obtain a high refractive index contrast to the subsequent anode layer. As anode we employed a highly conductive polymer. Laser interference lithography and physical plasma etching were used to pattern gratings into the Ta2O5 layer with a lattice constant of 370 nm and various grating depths. Mainly attributed to the outcoupling of the substrate modes, the structured devices exhibit a luminous flux which is up to four times higher compared to the unstructured reference devices.


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