Layered nanotechnology. Image source: Dr. Behnam Akhavan

A team led by researchers at the University of Sydney has developed a low-cost, sustainable, and off-the-shelf technology that can dim the screens of electronic devices, anti-reflective car rearview mirrors and smart building windows, all at the cost of current technology. 

It will replace one of the most scarce but extremely commonly used modern materials in the world: indium. A rare chemical element widely used in devices such as smart phones and computers, windshields, and automatic dimming windows.

Although a small amount is used to make smart device screens, indium is expensive because it is difficult to purchase; it naturally only appears in small deposits. Industrial indium is usually a by-product of zinc mining, which means that if the demand for optoelectronic devices such as LCDs and touch panels increases, there may be shortages.

Dr. Behnam Akhavan is in the plasma laboratory. Image source: Dr. Behnam Akhavan

Dr. Behnam Akhavan is an ARC DECRA researcher at the School of Biomedical Engineering, the School of Physics and the Sydney Nano Research Institute. He has developed a plasma-generated hybrid nanocomposite material that does not contain indium and provides low-cost, easy-to-use and environmentally friendly materials. Harmless electrochromic material. A technology that can darken the glass with the touch of a button or touch the screen. 

The research was published in "Solar Materials and Solar Cells" on July 19. 

The plasma generated material consists of tungsten oxide and silver, and can be applied to almost any solid surface, including flexible plastics.

Plasma is called the fourth state of matter and is produced by adding energy to gas. Plasma is most commonly used in fluorescent bulbs, neon lights, and some TV and computer screens.

The plasma of Dr. Behnam Akhavan. Image source: Dr. Behnam Akhavan

"When you change the transparency of wearable electronic devices or smart windows, electrochromic devices are working," said Dr. Akhavan.

"So far, these devices usually rely on rare indium and other materials to complete this work. What we have created is the manufacturer's dream: a technology that does not require indium, but uses a much lower production cost of plasma engineering three layers structure."

An early iteration of the technology was first produced in 2019, using a new method of tungsten oxide deposition called "HiPIMS" (the plasma technology used to make these materials).

Now, the team has developed a nanocomposite of tungsten oxide and silver instead of a bare tungsten oxide layer. This nanotechnology-based approach enables electrochromic devices to efficiently and quickly change colors according to user requirements. 

The plasma coating is transparent and conductive. They consist of a layer of silver that is about 10,000 times thinner than the width of a human hair and are placed between two nano-layers of nano-tungsten oxide decorated with silver nanoparticles. 

"These plasma-made coatings can then be applied to electronic paper, smartphones and glass windows, and can be dimmed by applying a small current."

There is no conflict of interest to share. The research was funded by the University of Sydney and the Australian Research Council.