In a paper published this week in the journal Nature, researchers from Switzerland’s École Polytechnique Fédérale de Lausanne detail the way in which they helped DSCs harvest energy from the full visible light spectrum. DSCs, a type of low-cost, thin film solar cell, use photosensitized dye attached to the surface of a wide band gap semiconductor to convert visible light into energy. Despite their financial and physical practicality, they’re not as efficient as conventional solar cells, which delegates both light absorption and energy generation to the semiconductor. This means that even though energy-generating windows have technically been possible for a while, the devices wouldn’t have been worth the resources.
This new efficiency record could change that. The team in Switzerland enhanced DSCs’ efficiency by meticulously controlling the assembly of dye molecules on the cells’ nanocrystalline mesoporous titanium dioxide (TiO2) films. Pre-adsorbing a single layer of hydroxamic acid derivative on the film’s surface allowed the scientists to improve the molecular packing and performance of two custom-designed sensitizers. These sensitizers were found to be capable of harvesting light from the entire visible spectrum.
During a simulation of standard air mass 1.5 sunlight—the air mass coefficient typically used to measure solar cells’ performance—the enhanced DSCs achieved a power conversion efficiency (PCE) of 15.2 percent. Considering the fact that 12.3 percent was the best-known DSC PCE in 2019, that figure is impressive, especially when you factor in that the enhanced cells maintained operational stability over 500 hours of testing. Better yet, when the scientists tested their enhanced DSCs on devices with a larger active surface area, they achieved a groundbreaking PCE range of 28.4 to 30.2 percent.
The team believes the enhanced 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, which would then use ambient light as an energy source.
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