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Proceedings Paper

Fluorenone defects in polyfluorene-based light-emitting diodes: emission properties and device performance
Author(s): Frank Jaiser; Xiaohui Yang; Dieter Neher; Roland Guentner; P. Scanduicci de Freitas; M. Forster; Ullrich Scherf
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Paper Abstract

The spectral characteristics of polyfluorene (PF) based light-emitting diodes (LEDs) are discussed. First, conditions that facilitate photo-oxidation of PF are investigated. We show that dense chain packing and addition of hole-trapping moieties lead to increased defect formation. Second, devices containing either a defined low concentration of keto-defects or of the polymer poly(9,9-octylfluorene-co-benzothiadiazole) (F8BT) are presented. Both types of blend layers were tested in different device configurations with respect to the relative and absolute intensities of green and blue emission components. It is shown that either blending of hole-transporting molecules into the emission layer at low concentration or the incorporation of a suitable hole-transporting layer reduces the green emission in the PF:F8BT blend, similar to what is observed for the keto-containing PF layer. We conclude that photo-oxidation leads to the formation of keto-defects that mainly constitute weakly-emissive electron traps.

Paper Details

Date Published: 16 February 2004
PDF: 9 pages
Proc. SPIE 5214, Organic Light-Emitting Materials and Devices VII, (16 February 2004); doi: 10.1117/12.505209
Show Author Affiliations
Frank Jaiser, Univ. Potsdam (Germany)
Xiaohui Yang, Univ. Potsdam (Germany)
Dieter Neher, Univ. Potsdam (Germany)
Roland Guentner, Bergische Univ. Wuppertal (Germany)
P. Scanduicci de Freitas, Bergische Univ. Wuppertal (Germany)
M. Forster, Bergische Univ. Wuppertal (Germany)
Ullrich Scherf, Bergische Univ. Wuppertal (Germany)

Published in SPIE Proceedings Vol. 5214:
Organic Light-Emitting Materials and Devices VII
Zakya H. Kafafi; Paul A. Lane, Editor(s)

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