Scientist use zinc oxide nanorods to grow white LEDs on paper substrate

Imagine a white luminous curtain waving in the breeze. Or wallpaper that lights up the room with perfect white light. In his doctoral thesis at Linkoping University , Gul Amin shows how white LEDs can be manufactured directly on paper. Gul Amin, who recently received his doctorate at the Physical Electronics and Nanotechnology group, Campus Norrkoping, shows 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 shows how they can 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.

According to Professor Magnus Willander who is leading the research: “This is the first time anyone has been able to build electronic and photonic inorganic semiconducting components directly on paper using chemical methods.” 

In one of the thesis’ other articles, published in Springer’s Journal of Material Science, Gul Amin also shows 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.