Ink jetting electronics

Johannes Canisius, who holds a doctorate in chemistry, works day-in, day-out on the development of new, highly complex molecules. Nevertheless, it’s still relatively easy for him to explain why this work is important. After all, most people understand the advantages of an inkjet printer: It prints on paper, which is lightweight and flexible, at low costs.

The R&D Department Head Organic Electronics wants to use this printing technique for the production of transistors. These electronic switches play a crucial role in controlling flat-panel displays, for example, for which Merck supplies the liquid crystals. The transistors themselves are currently made of the semiconductor silicon, which must be vapor deposited on a glass substrate at very high temperatures as part of an extremely complex process. This renders the displays rigid, heavy and breakable and makes them very expensive to produce. Organic semiconductors, however, are changing this. They consist of large molecule chains (polymers) or “small” molecules that impart insulating, semiconducting or conductive properties, depending on their chemical composition - properties required to build transistors. These polymers furthermore dissolve in certain liquids and can, like ink, be superimposed onto a substrate. 

“This enables us to print organic transistors like newsprint,” explains Canisius, “layer for layer over a large area and very cost-effectively.” This prospect will provide a big opportunity for Merck customers. The “electronic ink” will give them a technology that can completely alter the “flat-panel display” product, for example. How will it do this?  The ink can be processed at room temperature, so it can be used to print not only on glass, but also on flexible films to produce displays that are flexible, lightweight and very robust.

Merck’s Chilworth Technical Centre at University Science Park in Southampton, England. plays a central role in the development of the inks. Merck is also working here with customers from around the world to bring the new lisicon® materials to market maturity. The lisicon® family of products is based in part on organic semiconductors and borrows linguistically from the traditional silicon semiconductor, which it is intended to replace. Since the Technical Centre was founded in 2000, the number of employees here has grown nearly three-fold, with around 65 chemistry, physics, application technology, and analytical chemistry experts.

They come from England and Germany, Asia, North America and eastern Europe. Merck has gathered specialists from a total of 12 countries here, and the Chilworth location itself is responsible in no small part for this creative blend. “That’s because the prestigious universities of Cambridge, Oxford, London and Southampton are all in the immediate vicinity,” explains Luc S. Yao, who is responsible at Merck for marketing the organic electronic materials. “Southern England also enjoys a very good international reputation in the field of organic electronics.”

Merck invested roughly three million euros in the location in 2009, expanding the facilities and the possibilities. The company has established a high-tech environment that brings together all the process steps for printable electronics, from material development to application technology, under one roof. It all begins with a printing laboratory that bundles competencies in all the most common standard printing techniques, and also includes a chemical laboratory, where the materials are designed, manufactured and processed into suitable formulations; cleanroom zones, in which the materials are used in printed circuits to produce functional components; and finally a testing laboratory, where the finished products undergo a rigorous test regimen. Some of the research is so sensitive that certain areas are off-limits to visitors touring the facility. “We work in close and confidential collaboration with our customers,” stresses Yao. “That’s one of the things that characterizes us as a specialty chemicals manufacturer.”