Dresden 2014 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 29: Poster: Organic semiconductors and hybrid organic-inorganic heterostructures / Organic photovoltaics
HL 29.11: Poster
Montag, 31. März 2014, 17:00–20:00, P2
White top-emitting OLEDs with nanoparticle scattering layers — •Tim Schaefer1, Tobias Schwab1, Simone Hofmann1, Karl Leo1, and Malte C. Gather1,2 — 1Institut für Angewandte Photophysik, Technische Universität Dresden, George-Bähr-Straße 1, 01069 Dresden, Germany — 2School of Physics & Astronomy, University of St Andrews, North Haugh, St Andrews, KY16 9SS, Scotland, UK
We present white top-emitting organic light-emitting diodes (OLEDs) with a random nanoparticle scattering layer as outcoupling structure on top of the OLED stack. The nanocomposite scattering layer consists of titanium dioxide particles embedded into a transparent photoresist matrix. The scattering layer can be deposited directly on top of the small molecule OLED stack by solution-based dip- or spin-coating, without affecting the electrical performance of the device. The optical properties of the scattering layer are widely tunable by adjusting particle size and concentration. In first proof-of-principle experiments, the spectral radiant intensity for the blue spectral range of a white top-emitting OLED is nearly doubled and the overall external quantum efficiency at 1000 cd/m2 is increased by 18% in comparison to a reference device with standard organic capping layer for outcoupling. Furthermore, light scattering by the randomly distributed nanoparticles strongly improves the color stability with viewing angle. The proposed process is cost-efficient, scalable and compatible with different types of substrates and OLED architecture. It is expected that it can be readily adopted for large area OLEDs and is thus promising for lighting applications.