Brighter idea

3 min read

A three-year UK initiative to advance materials and production technology for light-emitting polymers aims to replace the traditional light bulb and help cut energy bills.

The light bulb is the globally recognised symbol of innovation, the iconic representation of the ‘eureka’ moment. But after nearly 130 years of brightening our lives, new technology could soon see it go the way of the gas lamp before it.

According to an increasingly vocal body of researchers, the properties of organic light-emitting diodes (OLEDs) and light-emitting polymers (LEPs) — thin films of material that emit bright white light under the application of electricity — are now advancing to the point where wide-scale commercialisation is imminent.

The appeal of the technology is irresistible: if the current pace of development continues, it will consume a fifth of the electricity used by traditional lighting and emit a pure white light far closer to daylight than anything that has gone before.

Also, because the technology is thin and flexible, it could kick-start a fundamental redesign of everything from the cars we drive to the buildings we live in.

Now, if a Durham-based consortium of researchers and engineers get their way, the UK could be poised to grab a sizeable share of a business predicted to be worth billions.

Dr Geoff Williams leads the £3.3m, thin organic polymeric light emitting semiconductor surfaces (TOPLESS) project, a three-year initiative to advance the materials and production technology for light-emitting polymers.

Bringing together LEP pioneer Cambridge Display Technology (or Sumation, as it is now known), Durham University and his own firm Thorn Lighting, Williams believes he has assembled a team that can hold its own with the other big initiatives.

Demonstrating the early fruits of the project at an event late last year, he showed a desk lamp that emits light at an efficiency of 20 lumens per watt (lm/W) through five 0.7mm thick panels and runs on 4V to 5V of power rather than the 240V used by incandescent lighting.

Although a neat device, its credentials are relatively humble alongside some of the rival efforts. In October, for instance, Osram and BASF launched an OLED that yields 60lm/W and meets the agreed international standard on brightness and colour required for general illumination.

But the TOPLESS technology has a big advantage, claimed Williams. It is potentially far simpler and cheaper to manufacture. ‘During OLED manufacture they typically have a red material, a blue material and a green material that they evaporate sequentially — then they’ve got supporting electron transport layers on either side. These are complex structures up to 16 layers thick and extremely difficult to process.’

In contrast, light-emitting polymer materials can be applied in solution using printing processes. Williams added that the next stage of the project is to evaluate different volume production techniques and win further government backing to move on to the prototype manufacturing stage at the new Printable Electronics Technology Centre in the North East Technology Park (NETPark) in Sedgefield, County Durham.

He believes the technology will enter the mainstream by stealth. The low volumes of early production runs will keep costs high and the technology is likely to appear first in niche automotive and architectural applications. But as economies of scale kick in and costs come down, applications will become more widespread, and the benefits of the technology will become clear.

Because of its low-voltage requirements, Williams is particularly excited about the potential for domestic lighting systems powered entirely by solar panels and wind turbines.

As well as enabling consumers to shave an estimated 50 per cent from their energy bills, he believes LEPS could help alleviate problems surrounding the anticipated shortfall in energy supply. ‘Twenty per cent of electricity produced by the UK’s power stations is used purely for lighting,’ he said. ‘If all buildings using light-emitting polymer technology were lit by renewable energy sources, one in five power stations could effectively become redundant.’

As costs fall further, Williams hopes the technology will have an impact in the developing world, with low-cost roll-up light-emitting polymers illuminating hospitals, schools and homes.

In the search for applications, Williams said he is trying to take the technology out of its ‘comfort zone’ and stimulate a dialogue with the wider business community about where the technology might be useful. This is leading to some interesting ideas.

For instance, as the TOPLESS devices generate no heat, they could be used to light refrigerators efficiently in supermarkets. Another intriguing opportunity in retail results from the technology’s ability to generate pure white light.

‘One of the targets is to have much better quality white light with a very high colour rendition so that when you buy an item from a shop and take it out into daylight, you don’t get a colour shift,’ said Williams.

In line with others working with OLED, Williams has high hopes for the technology. He expects it will begin appearing in new-build homes as early as 2013 and that by 2020 it could be the lighting technology of choice for all commercial lighting applications.

‘My prediction is that the market for domestic and commercial lighting will be worth €100bn (£89.5bn) a year by 2020. If organic lighting in any form achieves 10 per cent of that we will be doing very, very well.’

The UK, he claimed, is in a great position to exploit this market. ‘We’ve got everything we need to develop our own home-grown solutions from the full supply chain, to the academic and industrial models and the design capability to exploit a really integrated technology base.’