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Proceedings Paper

Characterization and optimization of OLED materials and layer sequences
Author(s): Wolfgang Kowalsky; Edo Becker; Torsten Benstem; Hans-Hermann Johannes; Dirk Metzdorf; H. Neuner; Joerg Schoebel
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Paper Abstract

In recent years, considerable effort has been put into the development of light emitting devices based on evaporated layers of organic semiconductors. To date, matrix displays consisting of organic light emitting diodes (OLEDs) have been brought into marketable commodity. OLED matrix displays offer high contrast, wide viewing angle and a broad temperature range at low power consumption. In contrast to polymer devices, OLEDs are processed in ultrahigh vacuum systems. The organic source materials are sublimated from effusion cells. Due to the sensitivity of organic thin films, device structuring by conventional etching techniques is not feasible and alternative structuring techniques were developed. Electrical current in organic devices is limited by the low conductivity of organic semiconductors and by energy barriers at the metal-organic semiconductor interface. Photoelectric measurements facilitate the determination of barrier height differences between various electrode setups. Further insight in the energy band alignment at organic heterointerfaces are gained by ultraviolet photoelectron spectroscopy (UPS). In addition to widely employed electrical (I-V, C-V) and optical (P-I) measurements, thermally stimulated current (TSC) and luminescence (TSL) allow the characterization and a more detailed understanding of carrier traps and charge transport in organic devices. Energy transfer in a doped OLED emitting layer can be investigated by time-resolved photoluminescence measurements.

Paper Details

Date Published: 2 February 2001
PDF: 9 pages
Proc. SPIE 4105, Organic Light-Emitting Materials and Devices IV, (2 February 2001); doi: 10.1117/12.416894
Show Author Affiliations
Wolfgang Kowalsky, Technische Univ. Braunschweig (Germany)
Edo Becker, Technische Univ. Braunschweig (Germany)
Torsten Benstem, Technische Univ. Braunschweig (Germany)
Hans-Hermann Johannes, Technische Univ. Braunschweig (Germany)
Dirk Metzdorf, Technische Univ. Braunschweig (Germany)
H. Neuner, Technische Univ. Braunschweig (Germany)
Joerg Schoebel, Technische Univ. Braunschweig (Germany)


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

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