VATIS UPDATE Article

Researchers at The University of Tokyo have developed a semi-transparent solar cell. Instead of conventional silicon, the cell uses the organic-inorganic hybrid material perovskite to generate electricity. This material efficiently absorbs blue light, while nanocubes of metallic silver improve the capture of red light, letting visually important green light through. Because of the efficient light capture, the perovskite layer can be made very thin, improving its transparency. The cell could therefore be used to coat windows.

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 accounted for 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.

The article, “Semi-transparent Perovskite Solar Cells Developed by Considering Human Luminosity Function,” was published in ­Scientific Reports.