Thorn Lighting in County Durham is leading a project to develop OLED materials and device architectures for large area white lighting applications which could replace fluorescent tubes.

“The materials we are hoping to develop will give high quality light similar to the sun,” project head Dr Geoff Williams told Electronics Weekly.

Emissive OLED panels are one of the two technologies touted as an eventual replacement for common fluorescent tubes and other forms of light bulb - the other being AC electroluminescent emitters.

Partners in the project are the University of Durham and Cambridge Display Technology (CDT), with the DTI providing £1.6m. Total initial funding amounts to £3.3m.

“The University is a centre of excellence for the analysis of polymeric energy levels,” said Williams. “We will be able to interrogate the re-combination process to act as feedback for the development of polymers.”

Under the terms of the grant, CDT through its Sumation joint venture will provide polymer OLED materials, device architecture and testing, as well as modelling and other technical expertise.

“Light emitting polymer materials can be solution processed and offer the potential of low cost manufacturing for large lighting panels,” said CDT.

The project is initially staying away from plastic substrates as they are too porous. “Initial products will be on solid substrates. Barrier layers [for plastic substrates] are not yet at the level that can inhibit the migration of oxygen and moisture,” said Williams, who would not elaborate on the type of solid substrate.

Performance targets include a colour rendering index better than common fluorescent tubes. “There will be peaks and troughs in the spectrum, but they won’t be huge troughs,” said Williams.

Another aim is that at the end of the three year project it will be producing emitters with 1,000cd/m2 with a 20,000hr life to 50 per cent brightness, said Williams. He added: “My expectation is it will be to 80 per cent.”

Electrical efficiency should be close to fluorescent tubes. “The target is 50 lumens/W in four to five years,” said Williams. “The eventual target has to be 150-200 lm/W. In 2015-2016 we will be knocking on this level. OLED lighting will be the first choice in 2020.”