Light Emitting Devices Could Power Lighting Revolution
April 30, 2007
An international research project has begun that could help bring to
mass-market organic light emitting devices (OLEDs), which could have far
reaching technological implications and cut the cost of lighting by
billion of pounds each year.
Impression of a
policeman wearing an OLED jacket
(Click here for an animation)
Because the devices are thin and flexible, lighting and electronic
display screens could for the first time be created on almost any
material, so that clothes and packaging can display electronic
The devices’ uses could vary from lighting that is many times more
efficient than current bulbs to clothes whose colour can be changed at
will and beer cans that display the latest football results.
At present, the devices
are used as displays in some mobile phones and MP3 players, but they are
not reliable enough for larger screens such as in TVs and computers as
they stop working after a few months.
But now an international consortium of researchers, led by the
University of Bath, UK, has begun an £850,000 ($1,700,000), three-year
project to put the science behind the devices on a firmer basis, so
helping make them efficient enough to be worth producing for the mass
The consortium, called Modecom, consists of 13 groups from nine
universities and two companies. Three groups are from the UK, six from
the USA, and one each from China, Belgium, Italy and Denmark. The
European Union is funding the European and Chinese partners.
The devices exploit a discovery made around 15 years ago that some
polymers have the unusual property of either turning electricity into
light, or light into electricity, depending on how the devices are made.
Because these polymers are thin and flexible, they could be used in a
multiplicity of ways:
• as a transparent window. This is like a conventional window during the
day, but when it gets dark a switch is turned on and the entire window
area emits light in a more efficient way than conventional or energy
saving bulbs, promising huge savings (see Related Links for an animation
• in garments which could change colour at the press of a button
• in clothing which displays strips of the polymer which run off solar
power, allowing electronic messages to be displayed which can be
updated. This could be useful for the emergency services such as police
or ambulance (see Related Links for an animation of this).
• in packaging for common goods that could be made to display electronic
messages such as health warnings and recipes, or could emit light (see
Related Links for an animation of this).
• as a source of solar power to top up mobile phones batteries
• as lightweight, solar power sources that could be rolled up and stored
and which would also be ideal for people requiring electricity in remote
locations, such as field researchers, mountaineers, sailors and military
The item is due to be featured on ITV West tomorrow (Friday 20 April).
The consortium is co-ordinated by Dr Alison Walker, of the University of
Bath’s Department of Physics, who said: "This is a long-term project,
and the contributions of many scientists are needed for its success.
Dr Alison Walker
“The experimentalists make measurements to test the efficiency of the
devices, but it’s hard to get a clear picture of what is going on at
present. This project is about making that picture clearer using
computer models to develop the theory.
“Success in achieving the goals of cheap, efficient and long lasting
devices is essential as we must do everything we can to reduce our
The polymer is made from chains of molecules, and is called organic
because these contain carbon. Electrons and holes injected into the
polymer film form bound states called excitons that break down under
electrical current, emitting light as they do so.
Dr Walker’s part of the consortium’s research uses a mathematical
technique called Monte Carlo analysis in which computer-generated random
numbers are used to plot the paths of electrons, holes and excitons as
they move across the film.
The results from this can be used to calculate how the chemical
structure and impurities affect the device’s performance. Chemists can
use this data to design more efficient materials.
The Modecom consortium will work on the molecular level and also look at
the workings of the device as a whole. This research will also aid the
understanding of the polymer materials used in plastic electronics in
applications such as electronic paper and intelligent labels on