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.
A researcher 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,” says professor Magnus Willander, who is leading the research.
Researchers have also shown 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. Since zinc oxide is a natural semiconductor of the n type (surplus negative charge), which is due to defects in the material, the researchers 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.
This story is reprinted from material from Linköping University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.