OLEDs are the future for consumer lighting. That’s what I was told 18 months ago when I visited the Holst Center in Eindhoven, the Netherlands.
Phillips, working with BASF, yesterday announced a practical breakthrough in the development of OLED (organic light-emitting diode) technology that allows its integration into car roofs. The OLEDs being used are transparent when off, allowing for a clear view outside the vehicle, and provide light when switched on. The transparent OLED sandwich structure can be powered by transparent solar cells. And they could be housed in a molded transparent polycarbonate roof module, creating a really innovative, lightweight, energy-saving approach to automotive design.
“This combination allows the driver to enjoy a unique open-space feeling while it generates electricity during the day and pleasantly suffuses the interior with the warm light of the transparent, highly efficient OLEDs at night,” said Dr. Felix Görth, head of Organic Light-Emitting Diodes and Organic Photovoltaics at BASF Future Business GmbH.
BASF and Philips have cooperated closely since 2006 within the OLED 2015 initiative of Germany’s Federal Ministry of Education and Research. BASF develops organo-chemical materials such as dyes that are used in the development and manufacturing of OLEDs by Philips.
OLED lighting works by passing electricity through one or more extremely thin layers of organic semiconductor material. Incandescent bulbs generate light by passing electricity through a wire, and fluorescent lamps pass current through a gas.
OLED light sources are just 1.8 millimeters thin. The layers of organic semiconductor material in an OLED are sandwiched between two electrodes – one positively charged and one negatively. The ‘sandwich’ is placed on a sheet of glass or transparent plastic, forming what’s called a substrate. When current is applied to the electrodes, they emit positively and negatively charged holes and electrons that combine in the organic layer of the sandwich to create a brief, high-energy state called ‘excitation’. As the layer returns to its original state, energy flows evenly through the organic film, causing it to emit light.
Using different materials in the organic films makes it possible for the OLEDs to emit different-colored light.
OLEDs can be used in television screens, computer monitors, and small portable screens used in mobile phones PDAs, and watches.
Phillips and others are excited about the technology because it has the potential to be very low cost in the future. Use of plastic in place of glass substrates will permit high-volume roll-to-roll manufacturing and the placement of OLEDs on flexible, portable structures.
A parent search shows that there is a lot of work under way to identify plastics that provide adequate barrier properties to protect the electronics. Popular choices included coated polyesters and polyimides.
When will we see a car with an integrated OLED roof? I suspect we may see a concept car using the idea at one of the big global auto shows in the next 18 months, but have no inside information. Traditional LEDs are increasingly used in automotive interiors to provide accent or mood lighting. The new development is a much bigger deal.
BASF will have a large booth at the entrance to the North Hall of NPE2012 in Orlando, FL April 1-5. Here’s hoping we can learn more at that time.