Holst Centre and Flex-o-Fab take first step towards “lighting by the mile”

 

Researchers from the EU-funded Flex-o-Fab project have successfully fabricated working OLED devices on a flexible barrier layer produced in a roll-to-roll process. The Flex-o-Fab project aims to help bring flexible OLEDs to the market by 2018. It brings together companies and institutes with strong background in organic electronics from across Europe and is coordinated by the Dutch research institute Holst Centre.

Produced on a PET plastic film, this breakthrough is a significant first step towards taking flexible OLEDs ‘from lab to fab’ and hence to commercial production. It draws on technical developments achieved within both Flex-o-Fab and Holst Centre’s joint research programme into high-performance flexible barriers for organic electronics.

The materials from which OLEDs are made are very susceptible to environmental factors and need to be protected from air and moisture. For flexible devices, the conventional approach of producing OLEDs on glass isn’t suitable. Holst Centre and its eco-system partners have been at the forefront of developing a flexible, thin-film barrier layer for use with plastic foils, and were the first to produce a high-performance barrier-foil in a R2R set-up.

Now, by performing in-situ planarization of the film immediately before depositing the barrier, Holst Centre researchers have been able to deliver R2R barriers that perform similar to barriers produced in sheet-to-sheet processes, thereby enabling potential cost savings in volume production. “We have successfully produced over 2.5km of R2R barrier film based on a single inorganic layer with water vapour transmission rates (WVTR) lower than 10^-5g/m² per day on commercial-grade PET foil,” said Sandeep Unnikrishnan, Roll-to-Roll Barrier project leader at Holst Centre.

This foil was then used to create working OLED devices. Researchers temporarily laminated the barrier foil to a glass substrate before depositing the OLED and the debonding the finished devices. All the OLED devices produced using this roll-to-sheet process worked, delivering performance comparable with devices fabricated on S2S barrier foils and with rigid OLEDs on glass.