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Title: Effect of Förster-mediated triplet-polaron quenching and triplet-triplet annihilation on the efficiency roll-off of organic light-emitting diodes

Abstract

We report the results of a systematic study of the interplay of triplet-polaron quenching (TPQ) and triplet-triplet annihilation (TTA) on the efficiency roll-off of organic light-emitting diodes (OLEDs) with increasing current density. First, we focus on OLEDs based on the green phosphorescent emitter tris[2-phenylpyridine]iridium(III) (Ir(ppy){sub 3}) and the red phosphorescent dye platinum octaethylporphyrin. It is found that the experimental data can be reproduced using kinetic Monte Carlo (kMC) simulations within which TPQ and TTA are due to a nearest-neighbor (NN) interaction, or due to a more long-range Förster-type process. Furthermore, we find a subtle interplay between TPQ and TTA: decreasing the contribution of one process can increase the contribution of the other process, so that the roll-off is not significantly reduced. Furthermore, we find that just analyzing the shape of the roll-off is insufficient for determining the relative role of TPQ and TTA. Subsequently, we investigate the wider validity of this picture using kMC simulations for idealized but realistic symmetric OLEDs, with an emissive layer containing a small concentration of phosphorescent dye molecules in a matrix material. Whereas for NN-interactions the roll-off can be reduced when the dye molecules act as shallow hole and electron traps, we find that suchmore » an approach becomes counterproductive for long-range TTA and TPQ. Developing well-founded OLED design rules will thus require that more quantitative information is available on the rate and detailed mechanism of the TPQ and TTA processes.« less

Authors:
 [1]; ;
  1. Simbeyond B.V., P.O. Box 513, NL-5600 MB Eindhoven (Netherlands)
Publication Date:
OSTI Identifier:
22594635
Resource Type:
Journal Article
Journal Name:
Journal of Applied Physics
Additional Journal Information:
Journal Volume: 119; Journal Issue: 16; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0021-8979
Country of Publication:
United States
Language:
English
Subject:
71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANNIHILATION; COMPUTERIZED SIMULATION; CONCENTRATION RATIO; CURRENT DENSITY; DYES; EFFICIENCY; ELECTRONS; HOLES; IRIDIUM; LAYERS; LIGHT EMITTING DIODES; MATRIX MATERIALS; MOLECULES; MONTE CARLO METHOD; PLATINUM; POLARONS; QUENCHING; SYMMETRY; TRIPLETS

Citation Formats

Eersel, H. van, Bobbert, P. A., Janssen, R. A. J., and Coehoorn, R., E-mail: r.coehoorn@tue.nl. Effect of Förster-mediated triplet-polaron quenching and triplet-triplet annihilation on the efficiency roll-off of organic light-emitting diodes. United States: N. p., 2016. Web. doi:10.1063/1.4947457.
Eersel, H. van, Bobbert, P. A., Janssen, R. A. J., & Coehoorn, R., E-mail: r.coehoorn@tue.nl. Effect of Förster-mediated triplet-polaron quenching and triplet-triplet annihilation on the efficiency roll-off of organic light-emitting diodes. United States. https://doi.org/10.1063/1.4947457
Eersel, H. van, Bobbert, P. A., Janssen, R. A. J., and Coehoorn, R., E-mail: r.coehoorn@tue.nl. 2016. "Effect of Förster-mediated triplet-polaron quenching and triplet-triplet annihilation on the efficiency roll-off of organic light-emitting diodes". United States. https://doi.org/10.1063/1.4947457.
@article{osti_22594635,
title = {Effect of Förster-mediated triplet-polaron quenching and triplet-triplet annihilation on the efficiency roll-off of organic light-emitting diodes},
author = {Eersel, H. van and Bobbert, P. A. and Janssen, R. A. J. and Coehoorn, R., E-mail: r.coehoorn@tue.nl},
abstractNote = {We report the results of a systematic study of the interplay of triplet-polaron quenching (TPQ) and triplet-triplet annihilation (TTA) on the efficiency roll-off of organic light-emitting diodes (OLEDs) with increasing current density. First, we focus on OLEDs based on the green phosphorescent emitter tris[2-phenylpyridine]iridium(III) (Ir(ppy){sub 3}) and the red phosphorescent dye platinum octaethylporphyrin. It is found that the experimental data can be reproduced using kinetic Monte Carlo (kMC) simulations within which TPQ and TTA are due to a nearest-neighbor (NN) interaction, or due to a more long-range Förster-type process. Furthermore, we find a subtle interplay between TPQ and TTA: decreasing the contribution of one process can increase the contribution of the other process, so that the roll-off is not significantly reduced. Furthermore, we find that just analyzing the shape of the roll-off is insufficient for determining the relative role of TPQ and TTA. Subsequently, we investigate the wider validity of this picture using kMC simulations for idealized but realistic symmetric OLEDs, with an emissive layer containing a small concentration of phosphorescent dye molecules in a matrix material. Whereas for NN-interactions the roll-off can be reduced when the dye molecules act as shallow hole and electron traps, we find that such an approach becomes counterproductive for long-range TTA and TPQ. Developing well-founded OLED design rules will thus require that more quantitative information is available on the rate and detailed mechanism of the TPQ and TTA processes.},
doi = {10.1063/1.4947457},
url = {https://www.osti.gov/biblio/22594635}, journal = {Journal of Applied Physics},
issn = {0021-8979},
number = 16,
volume = 119,
place = {United States},
year = {2016},
month = {4}
}