Scientists Create Thin, Transparent Solar Generator

Not many people think clunky solar roof panels are attractive, but we live with the unsightly installations because they provide clean, renewable energy.

It would be better if solar power could be generated by nearly invisible means – say a thin, transparent film that lays on the screen of your cell phone or over the windows of your house.

That’s what a team of researchers at Michigan State University has developed, and the name they came up with sounds like something out of Star Trek: “Transparent luminescent solar concentrator.”

MSU’s Richard Lunt says the key word is “transparent” because previous attempts to make such a panel work have resulted in weak energy production and, worse, the need for a highly colored panel.

“No one wants to sit behind colored glass,” says Lunt, an assistant professor of chemical engineering and materials science. “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.”

In an article in the journal Advanced Optical Materials, Lunt and his team reported developing small organic molecules in clear plastic panels that are used to absorb specific, nonvisible wavelengths of sunlight. He said these materials then react with only near-infrared and ultraviolet wavelengths, which then glow at yet another invisible wavelength within the infrared.

Next, this glowing infrared light is guided to the edge of the plastic panel where thin strips of photovoltaic solar cells convert them to electricity.

And yet with all this going on in your cell phone or on your window, “because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye,” Lunt says.

The new technology has potentially myriad applications. It can work in hand-held devices or be scaled up to commercial and even industrial applications at very little cost. “It opens a lot of area to deploy solar energy in a non-intrusive way,” says Lunt.

Still, there’s the issue of energy efficiency. For now, the device’s solar conversion efficiency is close to 1 percent, though the team’s goal is to optimize it to achieve efficiencies greater than 5 percent. Previous attempts with colored glass had an efficiency of about 7 percent. Conventional solar panels are about 25 percent efficient.

Lunt says his team will get there some day. “Ultimately, we want to make solar harvesting surfaces that you do not even know are there.”

By Andy Tully of Oilprice.com