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OPTOELECTRONICS A new flexible electrode for creating cheaper optoelectronics

| Author / Editor: Luke james / Johanna Erbacher

Australian researchers have demonstrated the potential for a new type of flexible electrode that could be used to create cheaper optoelectronics including solar cells and touchscreens. They even claim that, in theory, it could be used to create flexible “e-skins”.

Nanomesh on PET substrate as a kangaroo-patterned transparent and flexible circuit lighting up a blue LED.
Nanomesh on PET substrate as a kangaroo-patterned transparent and flexible circuit lighting up a blue LED.
(Source: Dr. Tengfei Qiu)

In fact, their flexible electrode could be used in any application that makes use of indium tin oxide (ITO), a composition of indium, tin, and oxygen that is electrically conductive and can take the form of a ceramic or alloy.

From laptop and touchscreen displays to thin-film solar cells and architectural windows to thin film photovoltaics, this ubiquitous material makes possible many of the technologies that we today take for granted. However, as indium becomes more and more scarce, ITO’s price is shooting up and this is inflating the price of components that make use of it, making them more expensive to produce. In addition to this increasing price, ITO is also very fragile, and this limits its applications.

Now, researchers in Australia at the ARC Centre of Excellence in Exciton Science may have found a new type of electrode that could be a perfect replacement for ITO on account of its flexibility and low price.

Nanosphere lithography

Dr. Eser Akinoglu, a contributing author at the ARC Centre, said: “The performance of the material is excellent, the transmission of above 90% and high electrical conductivity rivals the ITO benchmark." On the potential commercial applications for the team’s research, he commented that, in theory, it could be integrated into industrial roll-to-roll printing. If this is achieved, it would pave the way for cost-effective wearable technology and flexible screens that are truly flexible without compromise, not partly flexible with limitations.

The dielectric/metal/dielectric nanomesh electrodes were produced using nanosphere lithography. This is a simple and cost-effective deposition method that involves evaporating the desired combination of materials into a nanoscale pattern. The researchers found that using this method resulted in electrodes with precisely controlled perforation size, wire width, and uniform hole distribution that yielded high transmittance, low sheet resistance, and flexural endurance.

A sustainable alternative to current materials and processes

The research team’s new flexible electrode also has the added benefit of being recyclable, making them more sustainable and a potential alternative to current established materials and manufacturing processes. Commenting on the electrode’s recyclability, Dr. Akinoglu said: "It means that if you make a device like an electrochromic window, which may deteriorate in functionality after its life-span, you can take it apart, flush rinse the electrodes, and reuse them for another device."

In future, the research team wants to explore the potential of the material to create similar results at scale. Ultimately, they have a long-term view of achieving similar results while also demonstrating commercial viability. If the team is able to do this, it could bring to market a viable platform that will act as a boon for the development of next-generation optoelectronics that are both eco-friendly and cheaper to produce.

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