Coatings sputter out

Scientists from OxfordUniversity have developed a less expensive alternative to indium tin oxide — a transparent conductive coating used for products ranging from flat-screen TVs to solar cells.

The product is being commercialised through the university’s spin-out vehicle, ISIS Innovation.

Jamie Ferguson, project manager at ISIS Innovation, said the replacement material is created by doping zinc oxide with silicon. Unlike indium tin oxide, which is sputtered onto surfaces inside large industrial vacuums, he said the silicon-doped zinc oxide is formed on the surface of a product using a ‘solution phase’ technique.

Ferguson said that ISIS Innovation believes its deposition technique will be attractive to many companies looking to move away from sputtering.

‘Sputtering limits the size of the area you can deposit over,’ he said, adding that this becomes a problem when considering the increasing size of glass for products such as flat-screen TVs.

Ferguson said ISIS’s silicon-doped zinc oxide is not a perfect replacement for indium tin oxide.

‘These zinc-oxide-based materials offer an order of magnitude less conductivity,’ he said. ‘However, you don’t need the optimum performance indium tin oxide gives you for all products. We’re thinking of applications such as touch screens and flat-panel lighting. These are charge carrying so don’t need to be as conductive.’

While not as conductive, Ferguson added that ISIS’s zinc oxide-based material has just as good transparency as indium tin oxide.

He said companies will have to consider their material on a price-performance basis. ‘Zinc oxide is a thousand times cheaper than tin oxide.’

One reason for this, he added, is indium tin oxide is extremely rare and some scientists speculate it could run out by 2013.

ISIS Innovation is currently looking to license its material and deposition technique to any interested industrial partners.

Siobhan Wagner