title: On the interplay of waveguide modes and leaky modes in corrugated OLEDs.
abstract: Bragg gratings incorporated into organic light-emitting diodes (OLEDs) establish a coupling between waveguide modes and useful light (leaky modes). Here we demonstrate that the net coupling direction depends on the OLED stack design. We fabricated two different device structures with gold Bragg gratings. Angle resolved electroluminescence spectra were recorded. For the first device peaks of enhanced emission due to the Bragg grating are observed corresponding to a net energy transfer in direction of the leaky modes. The second device, on the other hand, exhibits dips in the emission spectrum. This reversed direction of energy transfer from the leaky modes to the waveguide modes is explained considering transfer matrix simulations of modal intensity distributions and device emission simulations. An OLED efficiency enhancement is only achieved, if the waveguide mode extraction is dominant.
authors: Light Technology Institute, Karlsruhe Institute of Technology, Kaiserstr 12, D-76131 Karlsruhe, Germany. julian.hauss@kit.edu
authors: Julian
authors: J
authors: Hauss
authors: Tobias
authors: T
authors: Bocksrocker
authors: Boris
authors: B
authors: Riedel
authors: Uli
authors: U
authors: Lemmer
authors: Martina
authors: M
authors: Gerken