Carsten Winnewisser

Coupling light from an organic light emitting diode (OLED) into a single-mode waveguide: Toward monolithically integrated optical sensors

Evanescent coupling is used to couple light from a polymer light emitting diode (PLED) into a planar single-mode waveguide. The PLED is monolithically integrated on top of the waveguide in a stacked configuration. Due to the waveguide’s proximity, the emission zone of the PLED and the waveguide modes overlap substantially, so that the PLED can directly excite the modes. An additional spacer layer between PLED and waveguide is shown to improve the coupling efficiency by about a factor of 5. For iridium-based diodes PLED-to-waveguide coupling efficiencies of as high as 3.2% have been obtained.

59.1: Invited Paper: Optoelectronic OLED Modeling for Device Optimization and Analysis

Organic light-emitting devices (OLEDs) consist of a stack of multiple thin film layers whose thicknesses influence both the optical and electronic performance. Upon injection and transport, the charge carriers may recombine to form excitons that diffuse and decay radiatively, thus leading to distinct recombination and emission zone profiles that determine device performance. Suitable simulation tools that allow a better understanding and efficient optimization of organic optoelectronics devices and materials are desirable.

Systematic studies of polymer LEDs based on a combinatorial approach

A novel, fully automated, fabrication and characterization apparatus for polymer light-emitting diodes (PLEDs) was developed. This high throughput apparatus allows the fabrication of 49 devices with a controlled variation of essential parameters like material, material composition, blend concentration, layer thickness, and annealing temperature. Up to now, due to a lack of elaborate design tools, extensive experimental effort is required in order to optimize novel materials, material combinations and device structures for polymer based LEDs. Our novel apparatus provides an extensive dataset which can be used for device optimization and a profound device modeling offering a deeper theoretical understanding of underlying device physics in PLEDs.

Submicrometer polymer transistors fabricated by a mask-free photolithographic self-alignment process

A simple method for patterning down to 400nm gaps between two thin-film electrodes is presented. The edge of the first electrode defines the gap via a photolithographic step using off-normal through-substrate exposure. It is demonstrated that the gap width can be controlled simply by adjusting the exposure angle and/or photoresist thickness. Using this process, poly(3-hexylthiophene) field-effect transistors with a submicrometer channel and a large channel width to length ratio of up to 5000 have been fabricated. Since the process is mask free, contactless, highly parallel, and offers high resolution, it is potentially suited for the high-throughput, low-cost fabrication of electronic circuits.

Optischer Näherungssensor basierend auf organischen Halbleitermaterialien (Optical Proximity Sensor based on Polymer Semiconductors)

Abstract Ein optischer Berührungs- und Näherungssensor wird in diesem Beitrag vorgestellt. Dieser Sensor basiert auf der monolithischen Integration polymerer Leuchtdioden (PLEDs) und polymerer Photodioden, wobei die organischen Halbleitermaterialien aus der flüssigen Phase verarbeitet wurden. Damit zeigt sich das zukünftige Potential integrierter optoelektronischer Systeme, wie z.B. berührungssensitive Monitore oder biochemische Sensoren auf flexiblen Substraten, die mittels spezialisierter Drucktechnologien im Rolle-zu-Rolle-Prozess herstellbar sein könnten.