Engineers from Monash University in Australia have made important breakthroughs with their semi-transparent perovskite cell technology, which is suitable for use as solar windows.

Semi-transparent perovskite solar cells (ST-PeSCs) allow some visible light to pass through while also harvesting solar energy, raising the prospect of buildings like skyscrapers becoming self-powering. In combination with more conventional rooftop solar, window and wall photovoltaics could help bring Melbourne’s CBD buildings close to self-sustaining, according to one study that Monash was involved in.

Previous work by the ARC (Australian Research Centre) Centre of Excellence in Exciton Science had developed a perovskite cell prototype that allowed 10 per cent of visible light to pass through, while simultaneously achieving a 17 per cent power conversion efficiency. Non-transparent silicon rooftop cells generally operate at about 20 per cent efficiency.

Using a combination of caesium and formamidinium in the initial perovskite composition, the Monash team recently developed new formulations of cells, allowing 20.7 per cent and 52.4 per cent of light to pass, with respective power conversion efficiencies of 15.5 per cent and 4.1 per cent. While the power conversion rates are lower than previous prototypes, the amount of visible light is now approaching levels suited to glazing, bringing the prospect of functional solar glass closer to reality.

“This works provides a major step forward towards realising high efficiency and stable perovskite devices that can be deployed as solar windows to fulfil what is a largely untapped market opportunity,” said project leader Professor Jacek Jasieniak, from the Department of Materials Science & Engineering at Monash University.

According to the researchers, these caesium and formamidinium perovskite solar cells demonstrated excellent long-term stability when tested for continuous illumination and heating, which mimics the conditions the devices would encounter in real-world use.

“By using photovoltaic technology commercially available today and incorporating the expected advances in wall and window-integrated solar technology over the next ten years, we could potentially see our CBD on its way to net zero in the coming decades,” Professor Jasieniak said in a previous statement.

“We began importing coal-fired power from the LaTrobe Valley in the 1920s to stop the practice of burning smog-inducing coal briquettes onsite to power our CBD buildings, and it’s now feasible that over one hundred years later, we could see a full circle moment of Melbourne’s buildings returning to local power generation within the CBD, but using clean, climate-safe technologies that help us meet Australia’s Net Zero 2050 target.”