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Proceedings Paper

Electronic traps in OLED transport layers: influence of doping and accelerated aging
Author(s): Juergen Steiger; Siegfried Karg; Heinz von Seggern
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Paper Abstract

The methods of thermally stimulated currents (TSC) and thermally stimulated luminescence (TSL) were employed to reveal the trap structure of the most prominent organic semiconductors materials such as tris-8-(hydroxyquinoline) (Alq3), N-N'-di(1-naphtyl)-N-N'-diphenylbenzidine ((alpha) -NPD), and 4,4',4'-tris-(N-2-naphtyl)-N-phenylamino- triphenylamine (1-Naph-DATA). The energetic trap depths and a lower limit of the trap densities were derived for all investigated materials by means of the initial-rise method and curve fitting techniques. Typical activation energies range between 0.1 and 0.6 eV and trap concentrations differ between 1014 and 1017 cm-3. Most materials exhibit trap levels with a single activation energy, however, in Alq3 a brought distribution of trap depths will be reported. In addition, the polarity of the dominant trap levels was determined by a comparison of TSC spectra from optically and electrically filled traps. Besides the trap detection and characterization the effect of doping and accelerated aging on the trap structure will be shown. TSC and TSL results on rubrene doped Alq3 reveals a characteristic shift in the trap depth indicating new rubrene related trapping site. The effect of aging on the trap structure of organic semiconductors in 'potentially harmful' atmospheres such as oxygen and humidity and their correlation to I-V characteristics will also be reported.

Paper Details

Date Published: 2 February 2001
PDF: 9 pages
Proc. SPIE 4105, Organic Light-Emitting Materials and Devices IV, (2 February 2001); doi: 10.1117/12.416902
Show Author Affiliations
Juergen Steiger, Darmstadt Univ. of Technology (Germany)
Siegfried Karg, IBM Zurich Research Lab. (Switzerland)
Heinz von Seggern, Darmstadt Univ. of Technology (Germany)

Published in SPIE Proceedings Vol. 4105:
Organic Light-Emitting Materials and Devices IV
Zakya H. Kafafi, Editor(s)

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