Zinc-Oxide Nanostructure Production Made Easy
Two scientists are on a path-breaking method to produce ‘sea-urchins’ to expedite the work capacity and efficiency of photovoltaic devices. Jamil Elias and Laetitia Philippe are the two scientists from Empa’s Mechanics of Materials & Nanostructures Laboratory who have been successful in producing these tiny ‘sea urchins’ which are ready to revolutionize solar-cell technology. New methods are generally difficult procedures, more so when the aim is to lend materials new characteristics as well by new processes. The two scientists from Thun have used materials that do not cost a bomb and they have achieved these results without utilizing any instrumentation that costs too much time and/or money.
Sea-urchins from polystyrene spheres:
These nano-structures that look like sea-urchins are created by a very easy electrochemical method. Microspheres of polystyrene form the basis of the template on which deposits of semiconducting zinc-oxide nano-wires form the three-dimensional substrates. Hollow spherical-shaped structures with spines sticking out on all sides are formed that look exactly like sea-urchins.
This experiment has been universally applauded as basic material polystyrene is an economical and easily available material and once the nano-wire developing process is completed, the polystyrene is removed and only the zinc-oxide nano-wire structures are ready for use in solar cells. The electrochemical method is also cost competitive and simple.
The electrochemical process:
This electrochemical process was developed successfully by Jamil Elias. By changing the polystyrene balls’ conductivity and the electrolytic properties, he has been successful in getting zinc oxide deposited densely on the surface of the small polystyrene microspheres, and regular nano-wires grow over time tightly packed on the underlying substrate. These spines increase the surface area considerably.
Uses of these sea-urchins:
These nano-structured ‘sea-urchin’-like looking surfaces have the potential to be used in electronic and optoelectronic devices – in short-wave lasers, light emitting diodes, solar cells and field-emission displays.
Swiss Federal Office of Energy is supporting the project for developing extremely thin absorbers (ETAs) for solar cells from these nano-structures and Laelatia Philippe and Jamil Elias are part of the research team which is working on zinc-oxide nano structures. Their research results were reported on-line in Advanced Materials attracted so much attention and gained so great popularity that it was chosen to appear on the inside front cover of the journal subsequently.
Expectations for ETA:
The researchers are hoping that the ‘nano-structured’ surface will have very effective light scattering properties. Absorbing a higher amount of sunlight and converting more radiated energy into electric power more effectively. The team is hopeful that spine-structured surface will increase the efficiency of photovoltaic devices significantly.