Swayam Prakasha (Self Illumination) is the property of some matters. Radium being one among them. Now, the principle is brought into application.
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A Pakistani scientist has succeeded in growing white LEDs directly on
paper.
With this breakthrough, people can now imagine a white luminous curtain
waving in the breeze or wallpaper that lights up your room with perfect white
light.
Gul Amin, who recently received his doctorate at the Physical Electronics and
Nanotechnology group, Campus Norrkoping, showed in his thesis how it is possible
to grow white LEDs, made from zinc oxide and a conducting polymer, directly on a
piece of paper.
He also described how they could be printed onto wallpaper, for example - a
method with a patent pending.
His research colleague, Naved ul Hassan Alvi, looked at his thesis from last
summer at various methods for producing - growing - different nanostructures of
zinc oxide on a number of different semiconducting materials.
Nanostructures of zinc oxide have a number of characteristics that make them
suited to the manufacture of white LEDs - among them a large band gap and
electrons that move easily and give off relatively large amounts of energy once
they have bounced back towards the nucleus. Plus the fact that the energy is
emitted as perfect white light.
Gul Amin has now gone further and succeeded in growing white LEDs directly on
paper. The active components are nanothreads of zinc oxide on a thin layer of
polydiethylflourene (PFO), a conducting polymer. But the paper has first been
coated with a thin, water-repellent, protective and levelling layer of
cyclotene, a resin.
"This is the first time anyone has been able to build electronic and photonic
inorganic semiconducting components directly on paper using chemical methods,"
said professor Magnus Willander, who is leading the research.
The article has been published in Wiley's physica status solidi - Rapid
Research Letters.
In one of the thesis' other articles, published in Springer's Journal of
Material Science, Gul Amin also showed how it is possible to grow nanothreads on
paper, blow them off the surface using ultrasound and collect them in the form
of a powder.
This powder can then be used to print the nanothreads of zinc oxide, and thus
LEDs, on paper or plastic in a normal printing press. That method also has
patents pending, with an application by Gul Amin along with the Ecospark firm,
founded by Magnus Willander, and Acreo.
Since zinc oxide is a natural semiconductor of the n type (surplus negative
charge), which is due to defects in the material, Gul Amin also combined zinc
oxide with copper oxide, which is of the p type (surplus positive charge), to
create a few different types of electrochemical sensors.
Following his doctorate, Gul Amin returned to his native Pakistan to pursue
his research, but at the Physical Electronics and Nanotechnology group the
potential of zinc oxide is being further explored, in combination with graphene,
copper oxide and other materials.
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