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Friday, July 9, 1999 Published at 19:18 GMT 20:18 UK


Sci/Tech

Plastics promise bright future

All dressed up and nowhere to glow

A television screen you can wear is just one of the bizarre applications possible with a new breed of glowing plastics.

Called light emitting polymers, they respond to an electrical current by giving off visible radiation.

By choosing the chemical structure of the polymer, scientists at Cambridge, England, have been able to create specific compounds which give off blue, green or red light - the raw ingredients of all visible colours.


[ image: Videophones could replace the cellphone]
Videophones could replace the cellphone
Because the plastics can be made in the form of thin films or sheets, they offer a huge range of applications. These include television or computer screens that can be rolled up and tossed in a briefcase, and cheap videophones.

Clothes made of the polymer and powered by a small battery pack could provide their own cinema show.

Camouflage, generating an image of its surroundings picked up by a camera would allow its wearer to blend perfectly into the background.

Chance discovery

The polymers' illuminating properties were spotted 10 years ago by three researchers at Cambridge University - Jeremy Burroughes, Richard Friend and Donal Bradley.

They noticed that if they put a voltage across a thin film of an exotic plastic called PPV, the plastic gave off a pale green light.

Sensing the commercial promise of the discovery they patented it and, backed by the millionaire rock band Genesis, set up a research and development company, Cambridge Display Technology (CDT).

The earliest light emitting polymers (or LEPs) were dim and inefficient, but the latest plastics are so bright they are difficult to look at directly.

Turning the plastic film into TV and computer screens is not as easy as it may seem.


[ image: Ultrathin screens]
Ultrathin screens
Transistorised screens are made up of tens of thousands of individual pixels, each of which lights up on command, forming the complex shifting display which creates the image we see.

Light emitting polymers are prepared from solution, so creating individual pixels is difficult.

Bubble jet technology

Richard Friend and his colleagues have got round the problem by adapting a bubble jet printer to squirt tiny blobs of red, green or blue coloured plastic onto an electrode array.

The dots are just 30 micrometres across, which makes possible high resolution screens at a fraction of the cost of the screens currently available.

"At first the cost will be comparable with a high-end active-matrix screen," said Craig Cruickshank, CDT's marketing manager. "But after that the price should plummet."

Despite their potential, commercial interest in the plastics was slow at first.

Things have changed in the last decade. In June CDT was valued at £80m. That figure is expected to rise to £300m within two years as industry catches on to the fact that the future could be not just bright and orange, but any colour you want.



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