The Race for Solar
|Back to Energy|
|Paul Buckley||April 11th 2011|
Researchers at the University of Warwick have developed a gold plated window as the transparent electrode for organic solar cells. The electrodes have the potential to be relatively cheap since the thickness of gold used is only 8 billionths of a meter. The ultra-low thickness means that even at the current high gold price the cost of the gold needed to fabricate one square metre of this electrode is only around $10.
Organic solar cells have long relied on Indium Tin Oxide (ITO) coated glass as the transparent electrode, although this is largely due to the absence of a suitable alternative. ITO is a complex, unstable material with a high surface roughness and tendency to crack upon bending if supported on a plastic substrate. The short supply of indium is making it relatively expensive to use.
An ultra-thin film of air-stable metal like gold would offer a viable alternative to ITO, which is the traditional material used in organic solar cells but until now it has not proved possible to deposit a film thin enough to be transparent without being too fragile and electrically resistive to be useful. ITO is a complex, unstable material with a high surface roughness and tendency to crack upon bending if supported on a plastic substrate. The short supply of indium is making it relatively expensive to use.
Research led by Dr. Ross Hatton and Professor Tim Jones in the University of Warwick ’s department of Chemistry has developed a rapid method for the preparation of robust, ultra-thin gold films on glass. Importantly this method can be scaled up for large area applications like solar cells and the resulting electrodes are chemically very well-defined.
Dr. Hatton commented, “This new method of creating gold based transparent electrodes is potentially widely applicable for a variety of large area applications, particularly where stable, chemically well-defined, ultra-smooth platform electrodes are required, such as in organic optoelectronics and the emerging fields of nanoelectronics and nanophotonics.”
The research team claims to have creates a simple, practical and effective method of depositing the films onto glass, and also reports how the optical properties can be fine tuned by perforating the film with tiny circular holes using something as simple as polystyrene balls. The University of Warwick research team has also had some early success in depositing ultra-thin gold films directly on plastic substrates, an important step towards realising the holy grail of truly flexible solar cells. The innovation is set to be exploited by Molecular Solar Ltd., a Warwick spinoff company dedicated to commercializing the discoveries of its academic founders in the area of organic solar cells.
Paul Buckley writes for EETimes, from which this article is taken.