Researchers develop low-cost transparent conducting film

The new coatings were developed as part of a programme to investigate low-cost, earth abundant materials and inexpensive deposition routes that could be used for large-area transparent conducting oxide coatings.

Transparent conducting oxides are used in a wide range of optoelectronic devices, including PV, LEDs and LCD touch screens. These materials are unique in that they can conduct electricity while being transparent to visible light. For optoelectronic devices to be able to emit or absorb light, it is important that the electrical contacts at the top of the device are optically transparent. Opaque metals and most transparent materials lack the balance between these two characteristics to be functional for use in such technology.

Currently, indium tin oxide (ITO) is used by more than 97 per cent of the transparent conducting oxide market as it possesses a near-ideal combination of high visible-light transparency and high electrical conductivity. However, indium metal is relatively scarce, expensive and has a highly volatile price. China produces more than half of the world’s indium and has recently significantly reduced its export quotas.

‘Our material is based on silicon-doped zinc oxide and is therefore lower cost and abundant in nature,’ Dr Jamie Ferguson of Isis Innovation, the university’s technology transfer company, told The Engineer. ‘We have targeted good performance at a lower price point and also have a method to deposit our materials from solution, whereas ITO is vacuum processed.’

Because of this solution-phase production method the team believes there is particular opportunity for the UK, which already has strong glass and high-technology manufacturing industries. Indeed, the team will be working with glass suppliers to integrate zinc-oxide films into production.

‘It’s important to point out that we are not proposing new PV materials, but rather a lower-cost transparent conducting oxide that could be used with PVs, displays and OLED lighting,’ Ferguson said.

The project will be co-supervised by Prof Edwards and Dr Vladimir Kuznetsov. Isis, which played a key role in the intellectual property protection and business planning for the technology, will continue to work with the academics to establish and secure funding for a new spin-out company, Oxford Advanced Conductors.