[Image above] Researchers from Michigan State University have developed a luminescent solar concentrator that’s transparent, offering the promise of completely clear energy-harvesting windows and smartphone screens. Credit: Yimu Zhao

There isn’t much these days that can’t be powered by solar energy.

Whether in planes, toilets, or roadways, solar is everywhere.

Thanks to the work of researchers at Michigan State University, however, that power is now completely transparent.

The team’s recently developed transparent luminescent solar concentrator (LSC) can create solar energy that isn’t visible on clear surfaces like windows or glass displays.


Yimu Zhao, a doctoral student in chemical engineering and materials science, and Richard Lunt, assistant professor of chemical engineering and materials science. Credit: G.L. Kohuth

“No one wants to sit behind colored glass,” says Richard Lunt, an assistant professor of chemical engineering and materials science, in an MSU release. “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.” (Aside: Disco is dead—or is it?)

Not only is the new LSC less colorful than other solar cells designed to encompass plastic materials, it’s also more efficient, offering a conversion efficiency of close to 1 percent.

To create the clear concentrator, Lunt and the MSU team, which includes MSU doctoral student Yimu Zhao, assistant professor of chemistry Benjamin Levine, and doctoral student Garrett Meek, developed small organic molecules that harvest the sun’s power by way of “specific nonvisible wavelengths of sunlight.”

According to Lunt, “We can tune these materials to pick up just the ultraviolet and the near infrared wavelengths that then ‘glow’ at another wavelength in the infrared.”


The transparent luminescent solar concentrator waveguide, shown with colorful traditional luminescent solar concentrators in the background. Credit: G.L. Kohuth

That “glow” is then converted to electricity by way of photovoltaic solar cells that are grouped in thin strips around the edge of the plastic.

“Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye,” he says.

The transparent concentrator’s efficiency could reach 5 percent if fully optimized; the current “best” LSC offering taps out at 7 percent.

Though still in the early stages of development, Lunt believes that the technology offers a great deal of promise in potential commercial or industrial applications—such as in building windows or smartphone screens—at a price that isn’t color- or cost-prohibitive.

The paper, published in a recent issue of Advanced Optical Materials, is “Near-infrared harvesting transparent luminescent solar concentrators (DOI: 10.1002/adom.201400103).

What do you think? Will this new transparent solar concentrator provide a clear path to smartphones that charge themselves?