Berlin 2012 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 6: Poster: Structural Ordering and Electronic Transport (joint focus with HL)

CPP 6.23: Poster

Montag, 26. März 2012, 17:30–19:30, Poster A

Increasing the performance of vacuum-processed organic light-emitting pin diodes by inserting an solution-processed hole-transport layer — •Thorsten Umbach, Stefan Schneider, Heike Klesper, and Klaus Meerholz — Universität zu Köln, Department Chemie, Luxemburgerstr. 116, 50939 Köln, Germany

High ohmic losses and a poor charge injection are the main obstacles on the way to stable organic light emitting diodes (OLED's) with high-power efficiencies and low driving voltages. A promising technique to get rid of these drawbacks is a molecular doping of charge transport layers. Throughout the last decade this has been successfully applied in vacuum processed devices leading to pin OLED architecture with internal efficiencies approaching unity.

However, major improvements in the field of OLED technology can be made by improving the light out-coupling. In conventional device architectures around 80% of the generated light is lost within the layers due to total internal reflection, wave guiding, and absorption.

By inserting an additional nanoporous hole-transport layer (HTL) into an OLED system we gain a strongly enhanced light output. The external quantum efficiency is increased up to 20%. This enhancement is due to a lower film density and the resulting lower refractive index of the HTL.

Here, we demonstrate the combination of both techniques. By optimizing the light out-coupling-properties by the HTL and the electronic structure by doping, the resulting hybrid devices have great potential to overcome most of the drawbacks OLED devices still suffer from.