Berlin 2015 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 30: Inorganic/Organic Interfaces: Towards Application
O 30.1: Vortrag
Dienstag, 17. März 2015, 14:00–14:15, MA 043
Increased light emission from organic light emitting diodes by surface plasmon polariton modification — •Cornelius Fuchs1, Paul-Anton Will1, Martin Wieczorek1, Malte C. Gather2, Simone Hofmann1, Sebastian Reineke1, Karl Leo1, and Reinhard Scholz1 — 1Technische Universität Dresden, Institut für Angewandte Photophysik, George-Bähr Str. 1, 01069 Dresden — 2University of St. Andrews, SUPA, School of Physics and Astronomy, North Haugh, St. Andrews, Scotland, UK, KY16 9SS
We demonstrate enhanced external quantum efficiency (EQE) from monochrome top-emitting light emitting diodes (OLEDs). The EQE is increased by about 20 % compared to an optimized reference device. The enhancement is achieved by modifying the refractive index of the hole transport layer (HTL) material. The reference HTL possesses a refractive index of 1.77, averaged over the emission spectrum of the emitter material, whereas the improved device uses a HTL with a lower refractive index of 1.52. Both devices are optimized for maximized first order outcoupling efficiency. Due to the low refractive index of the HTL, the dispersion relation of the surface plasmon polariton (SPP) excited at the opaque metal bottom electrode shifts to smaller in-plane wavenumbers compared to the reference HTL. The shift decreases the power lost into evanescent excitations. Hence, the outcoupling efficiency of the OLED is increased, leading to the enhanced EQE. The proposed method is found to be applicable to emitter materials possesing isotropic as well as oriented distribution of the transition dipole moments.