title: White organic light emitting diodes with enhanced internal and external outcoupling for ultra-efficient light extraction and Lambertian emission.
abstract: White organic light emitting diodes (WOLEDs) suffer from poor outcoupling efficiencies. The use of Bragg-gratings to enhance the outcoupling efficiency is very promising for light extraction in OLEDs, but such periodic structures can lead to angular or spectral dependencies in the devices. Here we present a method which combines highly efficient outcoupling by a TiO(2)-Bragg-grating leading to a 104% efficiency enhancement and an additional high quality microlens diffusor at the substrate/air interface. With the addition of this diffusor, we achieved not only a uniform white emission, but also further increased the already improved device efficiency by another 94% leading to an overall enhancement factor of about 4.
authors.affiliation: Light Technology Institute, Karlsruhe Institute of Technology, Kaiserstr 12, D-76131 Karlsruhe, Germany. tobias.bocksrocker@kit.edu
authors.forename: Tobias
authors.initials: T
authors.lastname: Bocksrocker
authors.forename: Jan Benedikt
authors.initials: JB
authors.lastname: Preinfalk
authors.forename: Julian
authors.initials: J
authors.lastname: Asche-Tauscher
authors.forename: Andreas
authors.initials: A
authors.lastname: Pargner
authors.forename: Carsten
authors.initials: C
authors.lastname: Eschenbaum
authors.forename: Florian
authors.initials: F
authors.lastname: Maier-Flaig
authors.forename: Uli
authors.initials: U
authors.lastname: Lemme