Solar power generating windows could well be on their way to commercial application in the real world, with the latest research demonstrating better efficiency and stability than the initial prototype created in 2020.

Two years ago, members of the ARC Centre of Excellence at Exciton Science created a solar window prototype that allowed 10% of visible light to pass through it, while achieving 17% power-conversion efficiency. This was close to the 20% power-conversion efficiency of normal rooftop silicon solar cells, which are not transparent and can’t be used as windows.

By replacing window glass with semi-transparent solar cells, buildings, particularly those with glass facades, would be able to generate their own power.

The 2020 research was based on solar cells made from perovskite materials, and which could be readily created in a laboratory and tuned to suit different purposes, including the type of energy they conduct and how much light they absorb, reflect and transmit.

Now, the same team, based at Monash University and CSIRO, have demonstrated power conversion efficiencies of 15.5% and 4.1% for different types of prototype semi-transparent solar cells, with visible light transmittance of 20.7% and 52.4% respectively.

Though the power-conversion efficiencies are lower than the previous study, the amount of visible light these new materials allow to pass through is significantly greater, increasing their viability for a wide range of real-world applications.

The combination of caesium and formamidinium in the initial perovskite composition delivered the best performance over different band gaps. In solar cells, the band gap is the minimum energy that is harnessed for delivering power from the sun.

Significantly, 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.

Professor Jacek Jasieniak from the Department of Materials Science & Engineering at Monash University, who led the project, says: “This work 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.”

The results of the new research have been published in the Advanced Science journal.

Image: A prototype semi-transparent perovskite solar cell at Monash University, Australia (Credit: Jae Choul Yu/ Exciton Science)