The gravure printing technique is currently under investigation as a possible method for the roll-to-roll production of OLEDs in the 6th framework EU funded project entitled ROLLED - "Roll-to-roll manufacturing technology for flexible OLED devices and arbitrary size and shape displays". The objective in the project is to fabricate an entire OLED structure by using roll-to-roll manufacturing methods and to examine, how the commercial production could be set up and integrated into an existing printing process. In order to attain a roll-to-roll compatibility, all the materials, inks and device structures need to be suitable for printing. Since, such OLED device structures are very sensitive to moisture and oxygen, high barrier materials to be applied as wet chemical coatings on transparent polymer films such as PET by common roll-to-roll coating techniques have been investigated. The barrier films on their respective substrates act as front and back side encapsulation materials, where the front side encapsulation material is to be used as a transparent and flexible substrate for OLED fabrication. The transmission rates to be achieved for both front and back side encapsulation for oxygen and water vapour are 5 mg m-2day-1 (corresponding to 7 cm3m-2day-1 for O2). In this paper, we show how light-emitting devices manufactured by gravure printing operate compared to the ones manufactured by traditional methods. Furthermore, we present recent results on the development of ITO nanoparticle coatings, cathode inks and flexible barrier materials.
Embedding of optoelectrical, optical, and electrical functionalities into low-cost products like product packages and printed matter can be used to increase their information content. For these purposes, components like displays, photodetectors, light sources, solar cells, battery elements, diffractive optical elements, lightguides, electrical conductors, resistors, transistors, switching elements etc. and their integration to functional modules are required. Also the need of rapid and reliable di-agnostic systems for wellness and healthcare applications is apparent. Today the time from sampling to result can take hours or even several days. In future the target is to analyze the sample within a few minutes for further action. Additionally, the price of the components for low-end products and disposable sensors has to be in cent scale or preferably below that. Therefore, new, cost-effective, and volume scale capable manufacturing techniques are required. Recent developments of liquid-phase processable electrical and optical polymeric, inorganic, and hybrid material inks together with biocompatible materials have made it possible to fabricate functional components by conventional roll-to-roll techniques such as gravure printing on flexible paper and plastic like substrates. In this paper, we show our current achievements in the field of roll-to-roll fabricated electronics, optoelec-tronics and biosensors. With examples of light guiding structures, organic light emitting diodes, biocompatible materials etc., we demonstrate the huge potential of roll to roll fabrication as a low cost mass production technology for future low end electronic products.
In the last decade, the processing of the waveguide structures on various substrates under mild conditions has been an appealing aim. The lithographic patterning of organic-inorganic hybrid materials processed by means of sol-gel technology allows the production of waveguides and other optical components.
We describe the synthesis of a new, photo-patternable, organically modified material with an improved ageing stability. Synthesis step does not involve widely used zirconia precursors, but it retains the same possibility of altering the refractive index by tailoring of the material composition. Refractive index values varied from 1.4700 to 1.5100. Measured birefringence values meet the requirements of most integrated planar optic applications. The synthesized material is compatible with silicon, glass and plastic substrates.
Material was analyzed using 29Si NMR techniques. The processed slab waveguides were characterized by using the prism coupling technique at various wavelengths. The attenuation in the waveguide was determined by the cut-back method, and it was found to be less than 0.5dB/cm at the wavelength of 830 nm. The morphology of the microstructures was measured by using the interferometer equipment. Slab waveguides rms values were in order of only 2 nm.