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Luminescent solar concentrators (LSC) produce electricity by focusing sunlight on a small area, which works in a similar way as setting fire to dry leaves using a magnifying glass.

However, the problem is that they are quite large and not so attractive, as they have the function, but lack beauty. There have been attempts to integrate solar concentrators with windows, but, as a result, they altered the color and transparency of the glass.

Now, material engineers at Michigan State University have designed totally transparent solar concentrators, which could be built into windows without blocking the light and disturbing the view, or even used on smartphone screens.

“No one wants to sit behind colored glass,” said the lead researcher of the study Richard Lunt in a press 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.”

The researchers achieved this by developing a system that diverts wavelengths invisible to the human eye. In particular, the concentrator absorbs light in the ultraviolet and near infrared spectrum and then transmits it in the infrared.

After this, the light is directed to the photovoltaic cells, which generate electricity. Since we are not able to perceive the ultraviolet and infrared wavelengths, the material remains transparent and looks to the human eye like ordinary glass.

The new technology is very promising but needs some improvements in terms of efficiency. The solar concentrator developed by the scientists of Michigan State University reaches only about 1% of solar conversion efficiency. However, they hope to increase it to 5%, as there are some non-transparent luminescent solar concentrators that are operating at an efficiency of about 7%.

Of course, there are other solar technologies that are far more effective, such as conventional solar panels that are typically installed on the roofs of the buildings, which absorb a wider range of wavelengths and thus reach 15-40% of solar conversion efficiency.

At the same time, the transparent technology has the potential to be used in a variety of applications, including commercial and industrial use.

As Lunt said, “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.”

Image credits: Yimu Zhao