Solar panels, though capable of producing clean renewable energy from just the rays of the sun, aren't necessarily aesthetically pleasing. They don't come in a wide range of colors and you can't see through them, which may keep them from being installed in places or for applications where they could be of use, such as on windows or as a decorative element.

 

But a new kind of photovoltaic cell could change all of that, as they can be produced in an ultrathin sheet and in various colors, and in turn might open up a lot of possibilities for wider adoption of solar energy.

 

Researchers at the University of Michigan have invented what they believe to be the "first semi-transparent, colored photovoltaics," which could eventually be used to cover the sides of buildings, as window shades, or even energy-harvesting billboards.

 

These prototype solar cells aren't nearly as efficient as those found in conventional dark-colored solar panels, because the colored areas in them reflect certain light wavelengths back to our eyes, instead of converting them to electricity, as current solar cells do. However, by being semi-transparent, and capable of taking on different colors, the new cells could be one of the missing links in wider adoption of solar energy, because they could be integrated into the design features of a structure.

 

To make the cells, an ultrathin sheet of amorphous silicon is sandwiched between two semi-transparent electrodes, which allow the light to hit the semiconductor, as well as carrying the electrical current generated by the cell.

 

Instead of being dyed to produce a color, the new solar cells are mechanically structured to transmit specific wavelengths of light by varying the thickness of the amorphous silicon layer in them. For example, on the prototype that emulates the US flag, the red regions are 31 nanometers thick, and the blue regions are just 6 nanometers thick, which transmit or reflect those colors to the human eye.