Tokyo - Roof-mounted solar panels are an increasingly common sight in many places. As a source of cheap, clean electricity, their advantages are obvious. However, most solar panels are opaque, and therefore cannot be placed over windows. Now, researchers at The University of Tokyo's Institute of Industrial Science (IIS) have made developments in the design of transparent solar materials.
Tokyo - Roof-mounted solar panels are an increasingly common sight in many places. As a source of cheap, clean electricity, their advantages are obvious. However, most solar panels are opaque, and therefore cannot be placed over windows. Now, researchers at The University of Tokyo's Institute of Industrial Science (IIS) have made developments in the design of transparent solar materials.
Conventional solar cells contain silicon, which captures sunlight and converts its energy to electricity. The panels are dark, because silicon absorbs light across a wide spectrum of wavelengths, allowing very little to pass through. This makes them efficient generators, but opaque materials, even though the thin silicon layer is coated on glass. Therefore, the challenge is to create a material that absorbs enough light to produce power, yet still admits enough to remain transparent.
To tackle this, the IIS researchers exploited the properties of the human eye. As recently reported in Scientific Reports, they took account of the fact that, for visual purposes, not all colors are equal. In fact, the eye is much more sensitive to green light, in the middle of the spectrum, than red or blue. According to the rules of "human luminosity," a good supply of green light is the main priority for visibility. Their new material was therefore designed to mostly absorb red and blue light, while letting green through.
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Image: Perovskite solar cell (Credit: University of Oxford Press Office)
