The end could be nigh for the old-fashioned light bulb. Scientists have developed wafer-thin sheets that fill a room with natural light at the flick of a switch, according to research published today.
The sheets are designed to be transparent but radiate brilliant white light when hooked up to an electricity supply. Because they do not warm up like traditional bulbs they waste far less energy, the researchers say.
Lighting sheets could brighten up homes and offices by being turned into ceiling tiles and wall panels, and even moulded to cover furnishings.
More than 20% of electricity used in buildings goes on lighting and nearly half of that powers incandescent bulbs.
The lighting sheets are made from light-emitting plastics which have the potential to be up to five times more efficient than standard bulbs.
"We hope it means the end of the light bulb. We don't really want them, they use an extraordinary amount of energy," said Stephen Forrest, a materials scientist at the University of Michigan. "The light bulb is ... a 135 or so year-old technology which hasn't been improved much ... it is a sponge for the energy we're producing - so I'd hope we'd be done with them in the not too distant future."
Dr Forrest and researchers from the University of Southern California managed to build up sheets of light-emitting plastics only a few millionths of a millimetre thick. The sheets are seeded with dyes that light up red, green or blue when an electric current passes through them. Together the colours combine to produce white light. "What we tried to do was get the balance of colours right so it mimics the light coming from the sun. The advantage is that when you go indoors everything will have the same appearance as when you're outside."
In a study published in the journal Nature today, the researchers describe how they were able to tune the sheets to convert electricity into photons, or particles of light, with 100% efficiency. Because the sheets do not heat up they should have a longer lifespan than traditional bulbs.
According to Dr Forrest, they should only need to be replaced every five to 10 years. "No new lighting system is going to take over the world instantly because of the economics, but we hope to start with bicycle lights and then maybe desk lamps to get started - and get to production scales that beat down the price."