Flexible, Affordable Light Source Can Printed

At its simplest, the flexible OLED element can be used in product packaging, posters or on supermarket shelves to attract the attention of consumers. It can also be connected to sensors measuring the freshness of food contained in packages. It can also be used to prevent product copying.

Arto Maaninen, Technology Manager of the VTT Technical Research Centre in Finland, predicts that the first OLED elements will be in commercial use within a couple of years. The project was coordinated by VTT,and project participants included INM, CSEM, Ciba, Hansaprint, UPM and PolylC.

An OLED is an organic light emitting diode, functioning in a way similar to LED lights. Importantly, the power consumption of the OLED light source is very low. Using organic materials, OLED light elements can be affordably manufactured using printing methods on large, flexible surfaces.

The OLED element developed under the ROLLED project is made from organic materials and is encapsulated in a moisture barrier film. The element is 200-250 micrometers thick, the equivalent to three or four sheets of paper.

The manufacturing method was tested in two demonstration tests. The first was presented as a two-colour OLED element that is attached to a product package. When the package is unopened, a green tick is displayed. When the package is opened, the fuse is blown and the tick changes into a red cross.

The second demonstration showed how the OLED element can be powered by an NFC telephone. The EU flag, with the stars representing the Members, was printed on a business card. When an NFC phone was placed near the card, the stars printed with the OLED elements lit up.

The current production cost of an OLED element is tens of cents. Researchers, however, are aiming for some end applications that cost as little as just a few cents. The acquisition cost of the equipment needed in the manufacturing process is clearly lower, and the speed of production is higher than in traditional production methods. The savings achieved can be up to half of the traditional production costs of OLED elements manufactured using a glass substrate.

The expertise developed during the production of flexible OLED elements can also be applied to the printing of solar cells used as a power source for various small portable devices.

The new OLED element was developed in the EU-funded ROLLED project, coordinated by VTT. Within this project VTT developed the printing process, CSEM different patterning technologies, and INM anode inks and barriers. VTT also developed a low work function cathode ink that enhances the functioning of the components by lowering the power supply voltage and reducing power consumption. It can be used in all printable electronics components, including transistors, solar cells and other electronics components.