New building blocks in electronics

EAM Cluster of Excellence innovations showcased at Hannover Messe

Flexible, printable and inexpensive: electronic parts built using nano-particles and organic molecules are increasingly flowing onto the market. The Engineering of Advanced Materials (EAM) Cluster of Excellence at Erlangen-Nuremberg University will be displaying three example applications at the Hannover Messe between 19 and 23 April 2010. Organic solar cells, thin film transistors and flexible sensors will be on display at Bayern Innovativ’s shared exhibition stand in Hall 2.

At the EAM Cluster of Excellence, electro-active organic molecules and inorganic nano-particles are being developed as essential building blocks and then, step by step, built up into highly ordered structures. This is how flexible electronic parts are created that can be produced using cost-effective printing process.

One such roll-to-roll process for solar cells, based on organic molecules, will be demonstrated in Hannover. In the future, foldable solar charger modules may supply power for mobile phones, laptops and MP3 players. Large format, lightweight versions could be envisaged on sun umbrellas or tents. The modules are built in several layers. Transparent, conductive metal oxide layers are spread on a flexible plastic film. Then comes the active layer that absorbs sunlight, converts it into a charge and feeds it into the electrodes. The charge can be conducted via a top electrode. Additionally, the solar cells are encapsulated in a plastic film to protect them from the environment. This has the added benefit of extending their lifespan.

Electronics for flexible screens and displays

Thin film parts for transistors with organic semi-conductors are produced at temperatures around 60°C. Thanks to this, in principle, they can be applied to flexible carrier materials such as polymer sheets and paper, making flexible screens and displays a possibility. Nevertheless, the parts would have to work at lower voltages for mobile applications, such as control transistors in flexible displays. That is why hybrid dielectric layers, i.e. organic/inorganic dielectric, are being used. These are no more than a few nanometres thick.

Flexible film transistors based on zinc oxide nano-particles offer similar opportunities. These particles are soluble making them cheap to process and, compared to soluble organic semi-conductors, they are less sensitive to environmental influences such as humidity and light. With a maximum temperature of 100°C, flexible substrates such as PEN plastic film could also be used in the manufacturing process.

Electrical parts such as flexible proximity and push-button sensors can be produced using ink jet printing. By placing your finger in the sensor area the capacity of the capacitor, composed of pressed silver electrodes, increases. An electronic circuit registers the change and turns on the diode. You can try this out for yourself with a push-button experiment at the Hannover Messe. In cooperation with the EAM, the Fraunhofer Institute for Integrated Systems and Device Technology is researching the use of printed electronics using inorganic nano-particles. Future areas of application abound wherever simple electronic functions can be replaced: advertising media in the logistics sector, for example, or digital identification for train, plane or concert tickets.

Der Exzellenzcluster Engineering of Advanced Materials

The Cluster of Excellence researches and develops new materials with structures which, hierarchically, range from molecular to macroscopic in size. In this research cluster, the only one of its kind in Germany, four material areas are being studied using a single methodical approach: nano-electrical materials, photonic and optical materials, catalytic materials and lightweight materials. The areas of functional particle systems, nano-analysis and electron microscopy, as well as modelling and simulation, which are transversally important and central to all fields, are tackled in new interdisciplinary centres. In 2007, the Erlangen-Nuremberg University Cluster of Excellence was awarded funding for five years as part of the nationwide Excellence Initiative run by the federal and state governments.

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uni | media service | news No. 71/2010 of 19.04.2010