The research project focuses on the opportunities that are opened by organic semiconductor devices as active optoelectronic components in lab-on-the-chip applications. Organic light emitting devices (OLEDs) have already been introduced successfully into the display market [1]. The active layer in these devices is either deposited from a solvent (in the case of conjugated polymers) or thermally evaporated in high vacuum (in the case of small organic molecules). In any case, the deposition onto micro patterned plastic or silicon substrates is possible. Patterning of the devices through shadow masks, lithographic or imprinting techniques can be undertaken.
The ease of processing and the tunability of the emission spectra all the way through the visible and the near UV part of the electromagnetic spectrum render these devices very interesting as light sources for integrated optical sensors. Being of amorphous structure organic semiconductor fabrication does not require epitaxial growth processes. The integration of organic light emitting devices is much less challenging than the integration of III-V-semiconductor devices by e.g., flip-chip bonding. Besides organic light emitting diodes, organic semiconductor lasers have also attracted much interest during the last years. Laser operation between 365nm and 700nm has been demonstrated under optical pumping for compact organic semiconductor lasers during the last year. As pump sources GaN laser diodes [2] could be used.
Organic semiconductor devices have also demonstrated their potential as efficient photo detectors. Those devices show quantum efficiencies comparable to the best silicon devices. While dynamic characteristics can be neglected for solar cells organic photodiodes can be tailored for fast reponse times suitable for pulsed detection schemes [3].
Besides the light sources and the detectors the coupling into the analyte is of key importance for an integrated sensor system. During the project the coupling into the sample volume through optical waveguides, free space optics or by using the evanescent field will be investigated and evaluated. Fundamental work has also to address the different detection quantities being possible. While the most obvious one is to use the organic emitter to excite a fluorophor by free space or waveguide optics, the use of local refractive index changes or the absorption could also be used.

[1] see, e.g., IEEE J. of Sel. Top. in Quant. Elec., 10(1), (2004)
[2] C. Karnutsch, M. Stroisch, et al., IEEE Photon. Technol. Lett., 19(10): 741-743 (2007)
[3] M. Punke, S. Mozer et. al. Proceedings of the SPIE 6185: 618505-1 (2006)