One car in this weekend’s 24 Hours of Le Mans endurance race, in France, will be sporting a new kind of sponsor logo: one lit up by flexible organic light-emitting diodes (OLEDs) that are integrated directly into the carbon fiber body of the car’s rear view mirrors.
It will be the first real-life application of a flexible OLED device, according to engineers at the Holst Center, an R&D organization in Eindhoven, The Netherlands, which created the light for the French racing team Oreca.
Today’s commercial OLED products, which are still expensive and few and far between, use inflexible glass to protect the organic elements.
But this weekend's race should provide an ideal testbed for flexible OLEDs, because of the extreme conditions of the race, says Ton van Mol, who heads up OLED research at Holst. Not only does the car have to go fast, he says, but it also has to last for 24 hours. OLEDs have gained popularity in research circles as lower power alternatives to other lighting and display sources like LCDs—the race car’s OLEDs run on just 6 to 8 volts—and because they can be made into thin, flexible sheets, which makes them ideal for area lighting, or even a “flat lamp” to carry around in a purse. Ideally, they could eventually be printed using a roll-to-roll process, like newspapers, which would make production relatively cheap.
But because they’re organic, OLEDs are very sensitive to water and oxygen (i.e. air), and they degrade fast. So they need excellent barrier layers built in to protect the organic layers from the outside world—layers that need to work a million times better than the aluminum barrier in potato chip bags, van Mol says. That makes them very, very expensive.
While glass is easy to use and works well as the barrier—hence its use in products like OLED TVs and a few new Samsung smartphone displays—it misses the point, because it’s not flexible. So Holst researchers are working to perfect flexible, multilayer barriers in their OLED stacks to keep them well protected.
Integrating OLEDs straight into the French team’s car (rather than sticking them on to the surface) is made possible by Holst’s collaborator in the project, Switzerland-based Huntsman Advanced Materials, which figured out the encapsulation technology using composite materials from its Araldite brand. The OLEDs on each mirror will actually read “Araldite.”
And, says van Mol, because the race is 24 hours, meaning half of it is in the dark, the Oreca car will be the only one that can show off its sponsor logos throughout the whole race.
That is, of course, “if it lights,” van Mol says. (He's not actually worried on that account.)
There’s still much work to be done on perfecting the barrier layers, in addition to other challenges like increasing OLED efficiency and lifetime, and reducing costs. But in the meantime, it’s off to the races for Holst’s OLED lights. Hope they shine bright.
Note: Costs of press visit to Imec research centers in Leuven, Belgium, and Eindhoven, The Netherlands, were covered by Imec.