Michigan State University develops transparent solar cell

Michigan State University (MSU) researchers have unveiled a near-transparent solar cell developed with organic molecules that generate solar energy when exposed to sunlight.

The light harvesting solar concentrator can be layered on top of a clear piece of glass without seriously altering or diminishing sunlight’s ability to pass through. Around the edge of the cell are small photovoltaic strips – effectively a miniaturized version of a standard solar panel – that reacts with infrared light, invisible to the naked eye, to produce solar electricity.

Currently, these panels are only delivering efficiency of 1%, but the MSU team are hopeful that 5% will be possible in the near future. Previous success in the translucent solar panel field – pioneered by Oxford PV and its use of perovskites – has achieved efficiencies in the range of 20-25%, but MSU’s Richard Lunt has argued that the key breakthrough here is the cells’ transparent nature.

"No one wants to sit behind colored glass," said the MSU 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."

Lunt also revealed how the small organic molecules embedded in the luminescent layer absorb specific non-visible wavelengths of sunlight, delivering solar energy and that all-important transparency.

"We can tune these materials to pick up just the ultraviolet (UV) and the near infrared wavelengths that then ‘glow’ at another wavelength in the infrared," Lunt told the University’s MSU Today. "Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye."

Technology you don’t know is there

The MSU researchers believe that this technology’s key appeal to the solar industry is its flexibility. At greater efficiencies and produced at a commercial or industrial scale, transparent solar panels could be integrated, non-intrusively, into most new buildings and even embedded into high-tech items such as smartphones.

"It opens a lot of area to deploy solar energy in a non-intrusive way," added Lunt. "It can be used on tall buildings with lots of windows or any kind of mobile device that demands high aesthetic quality.

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

Fully optimized, Lunt is confident that the solar harvesting technology the MSU team has developed can reach 5% efficiency, which, they feel, would then prove attractive to solar developers.