Highly transparent solar cells developed for windows
Courtesy UCLA Highly transparent solar cells developed for windows

The solar-harnessing window has long been on the green-building wish list. A clearly synergistic application, a window that can harvest energy from sunlight—especially on façades that encounter high solar gain—simply makes sense. The challenge has been developing a technology that allows enough light transmission and uninterrupted visibility to meet building occupant demands. Researchers at UCLA may have the answer to this problem, in the form of a highly transparent solar cell developed exclusively for window glazing. The key to the technology is its focus on infrared light, rather than visible light. A photoactive polymer takes advantage of this invisible part of the spectrum, converting the infrared illumination into usable electricity.

"These results open the potential for visibly transparent polymer solar cells as add-on components of portable electronics, smart windows and building-integrated photovoltaics and in other applications," said UCLA materials science professor Yang Yang, who directs the Nano Renewable Energy Center at California NanoSystems Institute (CNSI).

The solar cells offer a 4 percent power conversion, and employ a transparent electrode made of silver nanowire coated with titanium-dioxide nanoparticles. "We are excited by this new invention on transparent solar cells, which applied our recent advances in transparent conducting windows to fabricate these devices," added CNSI director Paul S.Weiss.