Spray-on clear coatings for cheaper smart windows

Researchers at RMIT University have developed a method for making clear coatings to cut the cost of energy-saving smart windows and heat-repelling glass.

The ultra-thin transparent coatings, which are over 100 times thinner than a human hair, block both harmful UV light and heat in the form of infrared radiation.

The scientists used a process called ultrasonic spray pyrolysis to fabricate smooth, uniform coatings of high optical and electrical quality.

Lead investigator Dr Enrico Della Gaspera said the pioneering approach could be used to substantially bring down the cost of energy-saving windows and potentially make them a standard part of new builds and retrofits.

“Smart windows and low-E glass can help regulate temperatures inside a building, delivering major environmental benefits and financial savings, but they remain expensive and challenging to manufacture,” said Gaspera, a senior lecturer and Australian Research Council DECRA Fellow at RMIT.

“We’re keen to collaborate with industry to further develop this innovative type of coating. The ultimate aim is to make smart windows much more widely accessible, cutting energy costs and reducing the carbon footprint of new and retrofitted buildings.”

The method could simplify the fabrication of smart windows, which can be both energy-saving and dimmable, as well as low-emissivity glass, where a conventional glass panel is coated with a special layer to minimise ultraviolet and infrared light.

It can also be optimised to produce coatings tailored to the transparency and conductivity requirements of the many different applications of transparent electrodes.

PhD researcher in Applied Chemistry at RMIT Jaewon Kim said the next steps in the research were developing precursors that will decompose at lower temperatures, allowing the coatings to be deposited on plastics and used in flexible electronics, as well as producing larger prototypes by scaling up the deposition.

“The spray coater we use can be automatically controlled and programmed, so fabricating bigger proof-of-concept panels will be relatively simple,” he said.

The research was supported through funding from the Australian Research Council, with key imaging and analysis conducted at RMIT’s Microscopy and Microanalysis Facility (RMMF).

The work was enabled in part by use of the Central Analytical Research Facility (CARF) at the QUT Institute for Future Environments.