Research in the production of energy from solar cells placed around luminescent materials is not new.
Past efforts, however, have yielded poor results – the energy production was inefficient and the materials were highly colored.
Now Dr Lunt and his colleagues at Michigan State University have developed transparent luminescent materials that use small organic molecules to absorb specific non-visible wavelengths of sunlight.
“We can tune these materials to pick up just the UV and the near-IR wavelengths that then ‘glow’ at another wavelength in the IR,” explained Dr Lunt, who is the senior author of the paper published in the journal Advanced Optical Materials.
The ‘glowing’ IR light is guided to the edge of the luminescent material where it is converted to electricity by thin strips of photovoltaic solar cells.
“Because the materials do not absorb or emit light in the visible spectrum, they look exceptionally transparent to the human eye,” Dr Lunt said.
One of the benefits of this new development is its flexibility.
While the technology is at an early stage, it has the potential to be scaled to commercial or industrial applications with an affordable cost.
“It opens a lot of area to deploy solar energy in a non-intrusive way. 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. Ultimately we want to make solar harvesting surfaces that you do not even know are there,” Dr Lunt said.
“More work is needed in order to improve its energy-producing efficiency.”
Currently Dr Lunt’s transparent concentrator has an efficiency of around 1 %, which is significantly lower than that of the best colored luminescent solar concentrator (7 %), but the scientists aim to reach efficiencies beyond 5 % when fully optimized.