Transparent Solar Cells a Thing of the Future

A new type of solar cell developed by researchers at Michigan State University (MSU) is changing the game of solar energy.

Organic photovoltaic cells - a type of solar cell that uses polymeric materials to capture sunlight - show tremendous promise as energy conversion devices, eScience News reported. They are both flexible and lost cost. This type of technology has been a challenge in the past because of the complexity of its power conversion processes, which involve separate charge formation and transport processes.

However, MSU researchers have found a way around this hurdle.

They developed what is called a transparent luminescent solar concentrator, which can be used on buildings, cell phones and any other device that has a clear surface. The key breakthrough in this design, one researcher says, is that it is transparent.

"No one wants to sit behind colored glass," Richard Lunt of MSU's College of Engineering said in a statement. "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."

The solar harvesting system uses small organic molecules developed by Lunt and his team to absorb specific nonvisible 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 explained.

As a result, the material appears transparent to the human eye.

While the technology is at an early stage, it has the potential to be scaled to commercial or industrial means while still being affordable. However, Lunt notes that with any new idea there are some kinks to work out. Currently the technology is able to produce a solar conversion efficiency close to one percent, with a goal of reaching five percent - the best luminescent solar concentrator (LSC) has an efficiency of around seven percent.

Still, Lunt and his colleagues are optimistic about their new development.

"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," he said. "Ultimately we want to make solar harvesting surfaces that you do not even know are there."

The research is described in more detail in the journal Advanced Optical Materials.