New transparent solar cells could help scientists create energy-generating windows

(Photo: Isaac Burke/Unsplash)Soon, the natural light filtering through your window will be able to do more than just brighten up your space. Scientists have achieved a level of efficiency for dye-sensitized solar cells (DSC) that could enable the creation of energy-generating windows.

IN paper published this week in the journal Nature, researchers at the École Polytechnique Fédérale de Lausanne in Switzerland detail how they helped DSCs harvest energy from the full spectrum of visible light. DSC, a type of low-cost thin-film solar cell, uses a photosensitized dye attached to the surface of a semiconductor with a wide band gap to convert visible light into energy. Despite their financial and physical practicality, they are not as efficient as conventional solar cells, which delegate both light absorption and power generation to the semiconductor. This means that even though power-generating windows are technically possible for a while, the devices would not be worth the resources.

This new performance record could change that. The team in Switzerland improved DSC efficiency by carefully controlling the assembly of dye molecules on the cells’ nanocrystalline mesoporous titanium dioxide (TiO2) films. Preadsorbing a single layer of a hydroxamic acid derivative on the film surface allowed the scientists to improve the molecular packing and effectiveness of two specially designed sensitizers. These sensitizers were found to be capable of harvesting light from the entire visible spectrum.

During a simulation at a standard air mass of 1.5 sunlight—the air mass factor commonly used to measure solar cell performance—the improved DSCs achieved a power conversion efficiency (PCE) of 15.2 percent. Considering the fact that 12.3 percent was the most prominent DSC PCE in 2019, this figure is impressive, especially when you consider that the improved cells maintain operational stability over 500 hours of testing. Even better, when the scientists tested their improved DSC on devices with a larger active surface area, they achieved a groundbreaking PCE range of 28.4 to 30.2 percent.

The team believes that improved DSCs could pave the way for energy-generating windows, skylights and greenhouses in the near future. They could even find a place in low-power electronic devices that would then use ambient light as a power source.

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