Australian scientists say semi-transparent solar cells that can be incorporated into window glass are a “game- changer” that could transform architecture, urban planning and electricity generation.

The researchers – led by Professor Jacek Jasieniak from the ARC Centre of Excellence in Exciton Science (Exciton Science) and Monash University – have succeeded in producing next-gen perovskite solar cells that generate electricity while allowing light to pass through. They are now investigating how the new technology could be built into commercial products with Viridian Glass, Australia’s largest glass manufacturer.

This technology will transform windows into active power generators, potentially revolutionising building design. Two square metres of solar window, the researchers say, will generate about as much electricity as a standard rooftop solar panel.

The research was also supported by the Australian Renewable Energy Agency (ARENA).

The idea of semi-transparent solar cells is not new, but previous designs have failed because they were very expensive, unstable or inefficient.

Professor Jasieniak and colleagues from Monash’s Materials Science and Engineering Department and Australia’s national science agency, CSIRO, used a different approach.

They used a commonly used solar cell component (known as an organic semiconductor that can be made into a polymer and used it to replace ARC Centre of Excellence in Exciton Science Spiro-OMeTAD), which shows very low stability because it develops an unhelpful watery coating. The substitute produced astonishing results.

“Rooftop solar has a conversion efficiency of between 15 and 20 percent,” Jacek said.

“The semi-transparent cells have a conversion efficiency of 17 percent, while still transmitting more than 10 percent of the incoming light, so they are right in the zone. It’s long been a dream to have windows that generate electricity, and now that looks possible.”

Co-author and CSIRO research scientist, Dr Anthony Chesman, says the team is now working on scaling up the manufacturing process.

“We’ll be looking to develop a large-scale glass manufacturing process that can be easily transferred to industry so manufacturers can readily uptake the technology,” he said.

Solar windows will be a boon for building owners and residents, and will bring new challenges and opportunities for architects, builders, engineers and planners.

“There is a trade-off,” explained Professor Jasieniak, “The solar cells can be made more, or less, transparent. The more transparent they are, the less electricity they generate, so that becomes something for architects to consider.”

He added that solar windows tinted to the same degree as current glazed commercial windows would generate about 140 watts of electricity per square metre.

The first application is likely to be in multistorey buildings.

Large windows deployed in high-rise buildings are expensive to make. The additional cost of incorporating the semi-transparent solar cells into them will be marginal.

“But even with the extra spend, the building then gets its electricity free!” Jasieniak says.

Image: A semi-transparent perovskite solar cell with contrasting levels of light transparency. Credits: Dr Jae Choul Yu

Branko Miletic

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