Semi-Transparent Solar cells

Researchers at The University of Tokyo have invented a semi-transparent solar cell. which uses the organic-inorganic hybrid material perovskite instead of conventional silicon to generate electricity. This material efficiently absorbs blue light, while nano cubes 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. Therfore the cells can be used to coat windows.

     Conventional solar cells that we have seen so far is contain silicon material, which captures sunlight and turns energy into electricity. These panels are dark, because silicon absorbs light across a wide spectrum of wavelengths, allowing a very little to pass through it and this is why it can efficiently generates electricity but as it is opaque material, same can not be used for both energy generators and transparent windows. 

      So, the challenge is to create a material that absorbs enough light to produce power, and still admits enough to remain transparent.

          Instead of silicon, the cell is based on a material known as perovskite. A thin perovskite layer absorbs sunlight to generate an electric charge, which is transmitted to an electrode layer sandwiched between perovskite and a glass backing. Perovskites are particularly good at absorbing the less visually important blue light.

       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. Their new material was therefore designed to absorb mostly red and Blue light while letting green through. according to Source.

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