Researchers in China say they have created a window-compatible film that could double the energy efficiency of an average household by combining coatings that block unneeded parts of sunlight with thin solar cells that turn windows into miniature electricity generators.

Their work appears in the journal Joule.

“Building-integrated photovoltaics are a great example of a market where silicon photovoltaics, despite their cheapness and performance, are not the most appropriate due to their dull appearance and heaviness,” says senior author Hin-Lap Yip, a professor of materials science and engineering at the South China University of Technology. “Instead, we can make organic photovoltaics into semi-transparent, lightweight, and colorful films that are perfect for turning windows into electricity generators and heat insulators.”

To construct a prototype capable of simultaneously outputting electricity and preventing excessive heating, the researchers needed to balance harvesting light for electricity generation, blocking it for heat insulation, and transmitting it as a window normally would. They put together a device that let the familiar visible portions of sunlight through, turned back the infrared light (a major heating culprit), and converted the near-infrared region in between into an electric current.

Back-of-the-envelope calculations suggest that in theory, installing windows outfitted with dual electricity-generating and heat-insulating properties could cut an average household’s reliance on external electric sources by over 50 percent. Although that estimate assumes that every square inch of every window would be panelled with multifunctional solar cells, it only requires a slight uptick in power-conversion performance from the 6.5-percent figure realized by Yip, Huang, and their colleagues.

“For this demonstration, we are not even using the best organic photovoltaics that are out there in this field,” says Yip. “Their efficiency is improving rapidly, and we expect to be able to continuously improve the performance of this unified solar-cell window film.”

These dual-function materials are still very much in their infancy, but the authors expect them to pave the way to new beneficial technologies.

“Making heat-insulating multifunctional semitransparent polymer solar cells is just the beginning of exploring new applications of organic photovoltaics,” Yip says. “A version tailored for self-powered greenhouses is only one of many impactful products that we want to develop for the future.”

Leave a Reply

Your email address will not be published. Required fields are marked *