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Owing to light weight, mechanical flexibility and ease of processing, organic semiconductor materials are being considered as promising candidates for future electronic and optoelectronic devices. In particular, light-emitting diodes from organic molecular materials (OLEDs) have turned out to be very attractive for display and lighting applications. In spite of huge progress in recent years, these devices still suffer from poor light extraction. The reason is that a major fraction of the excitations generated inside an organic semiconductor multilayer stack is lost to wave-guided or plasmon modes and is thus not converted into external radiation.
In this project we are specifically interested in the coupling of fluorescent molecules to surface plasmon polaritons (SPP) travelling at metal-organic interfaces or wave-guided modes travelling in a high-index layer. Varying experimental parameters like layer thicknesses, the type of organic molecules and metals in combination with numerical simulations, we investigate the different optical channels in organic multilayer structures. The goal is to elucidate the conditions for efficient coupling of radiation across thin metal layers into emissive modes, thus reducing plasmon and wave-guide losses.
Another direction of our work is to use the excitation of SPPs in thin metal films as sensing device. We have recently been able to demonstrate a surface plasmon resonance sensor using a thin metal film and an OLED as a planar light source being integrated on the same substrate. This new concept will be further investigated with respect to sensitivity, spectral requirements and possible applications as compact biosensor devices.
- W. Brütting (Ed.) (2005). Physics of
Organic Semiconductors, Wiley-VCH
- N.A. Reinke, C. Ackermann, W. Brütting
(2006). Optics Communications 266, 191.
- N.A. Reinke, C. Ostermayr, J. Neumann, J.
Frischeisen, W. Brütting, Sensors &
Actuators B (submitted)
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