Dresden 2017 – wissenschaftliches Programm
HL 64.19: Poster
Mittwoch, 22. März 2017, 15:00–19:00, P1C
Diffuse Transmission and Reflection of Light Scattering Polymer Substrates for Organic Light-emitting Diodes — •Pen Yiao Ang, Georg Marks, Abdalla Mahmoud, Axel Fischer, Simone Lenk, and Sebastian Reineke — Dresden Integrated Center for Applied Physics and Photonic Materials (IAPP) and Institute for Applied Physics, TU Dresden
Organic light-emitting diodes (OLEDs) are gaining more attention as the next generation of light sources. Still, the cost-performance ratio is not comparable to inorganic LEDs. One solution is to further enhance the performance of OLEDs by improving the outcoupling efficiency. Light trapped in waveguided modes of the substrate can be outcoupled if scattering particles are added to the OLED structure. The property of a scattering film to redirect light correlates with the haze factor, depending on the wavelength. Ideally, light is scattered into a direction which does not suffer from total internal reflection in the substrate. However, light having the right direction might be scattered in a way that it is coupled into waveguided modes or even reflected. Hence, it cannot be generalized that a higher haze factor automatically leads to a better performance of the scattering film. Here, we compare different self-made scattering films based on thin polymer substrates with incorporated nano-particles. By measuring the scattering of an incident light ray into all directions (360°), we identify the amount of direct transmission, diffuse transmission as well as diffuse reflection. The gained insights are related to the efficiencies of OLEDs using our substrates in order to specify optimal scattering properties.