European research delivers on OLEDs
Initiated in November 2012 and uniting the efforts of nine companies with six research institutes from five European countries, the project resulted in seven patent applications relating to the production of new transparent electrode and barrier materials for use in the next generation of flexible optoelectronics.
Sometimes using carbon nanotubes, metal fibres or thin silver, the flexible electrodes have been tested with several types of optoelectronic devices using rolls of over 100 meters in length, and found to be especially suitable for next-generation light sources and solar cells.
The roll of OLED light sources with the project logo (as per the top photo) was made using roll-to-roll techniques at Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP on a thin silver electrode developed within the project by Rowo Coating GmbH.
Such processing techniques promise to make light sources and solar cells much cheaper in future, but require flexible and transparent electrodes and water impermeable barriers, which were also investigated and developed by the TREASORES project.
According to Fraunhofer FEP, the electrodes from the project are technically at least as good as those currently used (made from indium tin oxide, ITO) but will be cheaper to manufacture and do not rely on the import of indium.
In the course of the project, new test methods were developed by the National Physical Laboratory in the UK to make sure that the electrodes would still work after being repeatedly bent – a test that may become a standard in the field.
A further outcome of the project has been the development, testing and production scale-up of new approaches to transparent barrier foils (plastic layers that prevent oxygen and water vapour from reaching the sensitive organic electronic devices). By combining the production of barriers with electrodes (instead of using two separate plastic substrates), the project has shown that production costs can be further reduced and devices made thinner and more flexible.
New devices using the patented electrodes and film barriers are expected to see the light in 2016.
The main challenge the project had to face was to make the barrier and electrode foils extremely flat, smooth and clean. Optoelectronic devices have active layers of only a few hundred nanometres, and even small surface irregularities or invisibly tiny dust particles can ruin the device yield or lead to uneven illumination and short lifetimes.
Led by Frank Nüesch from the Swiss Federal Laboratories for Materials Science and Technology (Empa), the TREASORES project’s partners included the Technical University of Dresden; Germany, the Fraunhofer FEP, Fraunhofer ISC, Fraunhofer IVV and Fraunhofer ISE, Germany; the University of Valencia, Spain; Aalto University, Finland; CIC Nanogune, Spain; NPL Management Ltd., United Kingdom; Osram GmbH, Germany; Canatu Oy, Finland; Amanuensis GmbH, Switzerland; Sefar AG, Switzerland; Amcor Flexibles, Switzerland and Germany; Rowo Coating GmbH, Germany; Eight19 Ltd., United Kingdom and Quantis Sàrl, Switzerland.
More information at https://treasores.eu
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