Technological breakthrough for cheaper lighting and flexible solar cells – to market in 2016

Flexible OLED light sources on transparent electrodes developed within TREASORES. These OLEDs were made by Fraunhofer FEP using a roll-to-roll process. (Image: Fraunhofer FEP)

In more than three years of work european scientists finally made future lighting technology ready to market.

They developed flexible lighting foils that can be produced roll-to-roll – much like newspapers are printed. These devices pave the path towards cheaper solar cells and LED lighting panels. The project named TREASORES was led by Empa scientist Frank Nüesch and combined knowhow from nine companies and six research institutes in five european countries.

In November 2012, the TREASORES project (Transparent Electrodes for Large Area Large Scale Production of Organic Optoelectronic Devices) started with the aim of developing technologies to dramatically reduce the production costs of organic electronic devices such as solar cells and LED lighting panels. Funded with 9 million Euro from the European Commission and an additional 6 million Euros from the project partners, the project has since then produced seven patent applications, a dozen peer-reviewed publications and provided inputs to international standards organisations.

New transparent electrodes and barrier materials

Most importantly, the project has developed and scaled up production processes for several new transparent electrode and barrier materials for use in the next generation of flexible optoelectronics. Three of these electrodes-on-flexible substrates that use either carbon nanotubes, metal fibres or thin silver are either already being produced commercially, or expected to be so as of this year. The new 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 was made using roll-to-roll techniques at Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology (Fraunhofer FEP) on a thin silver electrode developed within the project by Rowo Coating GmbH.

Flexible light sources for cheap and nice illumination

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 have also been developed by the TREASORES project. 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.

Tomasz Wanski from the Fraunhofer FEP said that because of the new electrodes, the OLED light source was very homogeneous over a large area, achieving an efficiency of 25 lumens per watt – as good as the much slower sheet to sheet production process for equivalent devices. 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.

Learn more: Technological breakthrough for cheaper lighting and flexible solar cells