Long viewed as a promising low-energy alternative to the incumbent technology organic polymer LEDs (PLEDs) - thin films of material that emit bright white light under the application of low DC voltages (4V), thus making them suitable for integration with emerging renewable power and battery technologies - have been held back by concerns over the quality of the light they produce and manufacturing difficulties. Hence the creation in 2007 by Thorn and its partners of Project TOPLESS – an investigation of Thin Organic Polymeric Light Emitting Semi-conducting Surfaces.

Match-funded by the Technology Strategy Board (TSB), the £3.3m project aimed to take PLED technology from the laboratory and improve its performance ready to be commercialised. “CDT are the world leaders in light-emitting polymers so we weren’t starting from scratch– they had 20 years of high-level research knowledge to bring to the project,” said project leader Dr Geoff Williams of Thorn.

“We took the materials from being a research-oriented and driven technology to being an industrial and customer-oriented technology. We had to address performance in terms of efficiency, lifespan, colour, brightness and stability: the parameters that made it suitable for lighting applications in an office environment.”

All organic LEDs have the advantage of being incredibly thin and lightweight, often one-two thousandth the thickness of a human hair. Where PLEDs have an advantage is in their production process. Using long-chains rather than small organic molecules means the semiconductor film can be printed from solution onto a substrate at atmospheric pressure, instead of thermally evaporated in a vacuum.

“We’re going for a painting or printing process rather than a high-energy consuming technology,” added Williams.

The consortium – recently expanded with the arrival Tridonic, Pilkington and Conductive Inkjet Technologies (CIT) - has now begun the next stage of research: a £4.3m programme to produce a pilot line at the Printable Electronics Technology Centre (PETEC) in Sedgefield, supported again by a 50% grant from the TSB. This will help establish the best applications for PLEDs and test and develop new electronic and glass components and the manufacturing scenarios needed to produce them. Prototypes for different applications – and data to show the technology is scalable – could be ready as early as 2011.

“We’ve taken the technology to a level playing field with the small molecule OLED research in Germany, the Far East and the US in terms of capability,” concluded Williams. “We’ve put the UK on the global map and we’ve put polymer LEDs for lighting alongside OLEDs at the front of lighting technology.”

Now in its fourth year, the prestigious awards scheme is run by The Engineer, the leading magazine and website for technology and innovation, in conjunction with main sponsor BAE Systems.

For further information visit: http://www.theengineer.co.uk/awards/project-topless/1006236.article