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Proceedings Paper

Efficient screening of electron transport material in multilayer organic light-emitting diodes by combinatorial methods
Author(s): Christoph Schmitz; Peter Poesch; Mukundan Thelakkat; Hans-Werner Schmidt
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Paper Abstract

A combinatorial approach combining vapor deposition of organic molecules and a mask technique was used to prepare on one substrate a matrix of 49 organic light emitting diodes (OLEDs) with different configuration and layer thickness. A landscape library with two orthogonal, linear gradients of an emitter and a hole blocking electron transport material on top of a hole transport layer of constant thickness was prepared. The aim of this experiment was to investigate the influence of an additional electron transport material on the efficiency. Using a semi-automated measurement set-up, the device parameters for each of the 49 OLEDs were evaluated. The existence of an optimum Alq3 layer thickness for two-layer devices ITO/TPD/Alq3/Al is confirmed and such an optimized two-layer structure could not be improved by adding an additional hole blocking layer to the optimum Alq3 layer. But an improvement of photometric efficiency can be obtained by replacing the optimum Alq3 layer thickness by certain combinations of Alq3/spiro-Quinoxaline layers.

Paper Details

Date Published: 17 December 1999
PDF: 9 pages
Proc. SPIE 3797, Organic Light-Emitting Materials and Devices III, (17 December 1999); doi: 10.1117/12.372739
Show Author Affiliations
Christoph Schmitz, Univ. Bayreuth (Germany)
Peter Poesch, Univ. Bayreuth (Germany)
Mukundan Thelakkat, Univ. Bayreuth (Germany)
Hans-Werner Schmidt, Univ. Bayreuth (Germany)

Published in SPIE Proceedings Vol. 3797:
Organic Light-Emitting Materials and Devices III
Zakya H. Kafafi, Editor(s)

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