A group at Michigan State University led by Richard Lunt have put the “transparent” in “transparent” in this existing field. Past efforts by others have led to poor energy efficiency and highly colored materials but that seems to be changing.

sunlight charging

“No one wants to sit behind colored glass,” said 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.”

Solar paneled smartphone: Organic molecules to electricity

The technology was arrived at by Lunt and his team when they began using small organic molecules they developed to absorb on visible wavelengths of sunlight.

“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,” he said. That glowing infrared light is then “walked” over to the edge of the plastic where it meets thin strips of photovoltaic solar cells to convert that light to electricity.

The ramifications and potential uses are myriad but Lunt admits far too expensive and energy inefficient at present, but the group aims to change that. As Americans now list the power needs of smartphones among their biggest causes of stress, god help us, a phone that could charge itself in the sunlight would certainly be welcome.

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

Solar paneled smartphone: Bringing down cost while boosting efficiency

In addition to powering or charging phones and tablets buildings with lots of windows could essentially power themselves as the technology becomes cheaper and more scalable.

“It opens a lot of area to deploy solar energy in a non-intrusive way,” Lunt said. “It can be used on tall buildings with lots of windows or any kind of mobile device that demands high aesthetic quality like a a phone or e-reader. Ultimately we want to make solar harvesting surfaces that you do not even know are there.”

The team is looking to reach a solar conversion efficiency of 5% and beyond but are at under 1% now so there is certainly work to be done. The best non-transparent use of LSC has an efficiency of around 7%.