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Proceedings Paper

Optical analysis of down-conversion OLEDs
Author(s): Benjamin Krummacher; Markus Klein; Norwin von Malm; Albrecht Winnacker
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Paper Abstract

Phosphor down-conversion of blue organic light-emitting diodes (OLEDs) is one approach to generate white light, which offers the possibility of easy color tuning, a simple device architecture and color stability over lifetime. In this article previous work on down-conversion devices in the field of organic solid state lighting is briefly reviewed. Further, bottom emitting down-conversion OLEDs are studied from an optical point of view. Therefore the physical processes occurring in the down-conversion layer are translated into a model which is implemented in a ray tracing simulation. By comparing its predictions to experimental results the model is confirmed. For the experiments a blue-emitting polymer OLED (PLED) panel optically coupled to a series of down-conversion layers is used. Based on results obtained from ray tracing simulation some of the implications of the model for the performance of down-conversion OLEDs are discussed. In particular it is analysed how the effective reflectance of the underlying blue OLED and the particle size distribution of the phosphor powder embedded in the matrix of the down-conversion layer influence extraction efficiency.

Paper Details

Date Published: 25 February 2008
PDF: 17 pages
Proc. SPIE 6910, Light-Emitting Diodes: Research, Manufacturing, and Applications XII, 691007 (25 February 2008); doi: 10.1117/12.768948
Show Author Affiliations
Benjamin Krummacher, OSRAM Opto Semiconductors GmbH (Germany)
Markus Klein, OSRAM Opto Semiconductors GmbH (Germany)
Norwin von Malm, OSRAM Opto Semiconductors GmbH (Germany)
Albrecht Winnacker, Electrical Engineering Materials, Univ. of Erlangen-Nuremburg (Germany)

Published in SPIE Proceedings Vol. 6910:
Light-Emitting Diodes: Research, Manufacturing, and Applications XII
Klaus P. Streubel; Heonsu Jeon, Editor(s)

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