Scientists have moved a step closer to producing electrically-powered plastic laser diodes that could be used in Blu-ray players.
Currently the laser diodes in such consumer optical storage devices are made out of inorganic semiconductors like gallium arsenide, gallium nitride and other semiconductor alloys related to them.
Now, researchers at Imperial College in London have demonstrated a class of plastic semiconductor materials that may allow the low-cost manufacture of electrically-powered plastic laser diodes.
As well as reducing the cost of devices such as Blu-ray players the development could allow plastic laser diodes to operate across a much more substantial wavelength range.
Professor Donal Bradley, lead author of the new study and head of Imperial’s Department of Physics said the development was “a real breakthrough”.
“In the past, designing polymers for electronic and optoelectronic devices often involved maximising one key property in a material at a time,” he said.
“When people tried to develop plastic semiconductors for laser diode use, they found that optimising the material’s charge transporting properties had a detrimental effect on its ability to efficiently emit light, and vice versa.”
The study’s co-author, Dr Paul Stavrinou, added: “The modifications made to the PFO structure have allowed us to convincingly overcome this perceived incompatibility and they suggest that plastic laser diodes might now be a realistic possibility.”
One of the main stumbling blocks to using plastic semiconductor laser diodes is that, until now, no plastics had been found that could sustain a large enough current whilst also supporting the efficient light emission needed to produce a laser beam.
Now the Imperial physicists have done just that. The plastics studied, synthesised by the Sumitomo Chemical Company in Japan, are closely related to PFO, an archetype blue-light emitting material.
By making subtle changes in the plastic’s chemical structure the researchers produced a material that transports charges 200 times better than before, without compromising its ability to efficiently emit light – indeed the generation of laser light was actually improved.
The research team argues that the future laser diodes made out of the material they have developed may generate light emissions covering the spectrum all the way from near ultraviolet to near infrared.

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