Micro-spherically textured organic light emitting diodes: A simple way towards highly increased light extraction

We demonstrate a method to increase the efficiency of white organic light emitting diodes (WOLEDs) by a factor of up to 3.7. By fabricating the WOLED on top of a monolayer of SiO2-microspheres we texture the WOLEDs spherically. We attribute the significant increase of the device efficiency to a larger area on the same footprint and to an enhanced outcoupling of waveguide and substrate modes. Measurements reveal that the I–V characteristic of the device as well as the emissive characteristic remains unchanged.

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► OLEDs are textured spherically by building them on a monolayer of SiO2–microparticles.
► Efficiency enhancement of a factor up to 3.7 due to outcoupling of waveguide and substrate modes.
► High efficiency enhancement without changing the I–V or emissive characteristic.