Solar power with a view is the latest promise in energy research, as U.S. scientists say they've come up with a transparent method for harvesting the sun's rays for production of electricity.
The development could mean that light-catching windows in houses and buildings could soon provide yet another source of green energy, Michigan State University researchers say.
Their creation, dubbed a transparent luminescent solar concentrator, can be applied to a window to generate solar energy while still allowing a view out through the window, they report in the journal Advanced Optical Materials.
The concentrator consists of a thin layer of organic molecules absorbing near-infrared and ultraviolet wavelengths of sunlight, pushing them to photovoltaic solar cells at the edges of a window's surface to be converted to electricity.
Still in its early stages, the technology needs to be more efficient, the researchers acknowledge, since the coating's solar conversion rate is around just one percent compared to the almost 20 percent of other solar energy technologies.
It is hoped that it can be boosted to 5 percent with more research, they say, and while that may not seem like a lot it could add up with every window in a building being a potential solar energy collector.
It could also be applied to a surface like a smartphone screen or a tablet screen to provide energy to recharge such devices, says researcher Richard Lunt of the university's College of Engineering.
"It opens a lot of area to deploy solar energy in a non-intrusive way," he says. "It can be used on tall buildings with lots of windows or any kind of mobile device that demands high aesthetic quality like a phone or e-reader."
Research into films or coatings to harvest solar energy is not new, Lunt notes, but previous efforts were inefficient and the materials employed were usually highly colored - not an ideal situation.
That's why complete transparency was a goal of the current research and why they developed their coating to absorb non-visible wavelengths of light, he says.
"No one wants to sit behind colored glass," says Lunt, a professor of material science and chemical engineering. "It makes for a very colorful environment, like working in a disco. We take an approach where we actually make the luminescent active layer itself transparent."
"Ultimately we want to make solar harvesting surfaces that you do not even know are there."
