A group of researchers at the Fraunhofer Institute for Applied Optics and Precision Engineering along with a team from the Friedrich-Schiller University are working to develop new cost efficient solar panels available in a wide range of colors. By combining what should be an aesthetically pleasing design along with highly efficient solar cells, the teams hope to get architects and designers interested in using solar panels as part of new construction.
The team came up with semiconductor-insulator-semiconductor (SIS) solar cells made from paper-thin crystalline silicon wafers. Their SIS cells have an insulator layer made from an optically neutral barrier that has a hundred-nanometer thick transparent conductive oxide (TCO) coating serving to guide photons to the semiconductor layer below it. An added bonus is that the TCO layer has a lower refractive index than silicon, so the SIS cells reflects much less light. By changing the thickness or the refractive index of the TCO, they can change the color of the solar cell, and the team found that the TCO coating has barely any impact on the efficiency of the cell. They think that they can hit 20% efficiency with their cells.
The team is currently developing an inkjet printing process that will deposit the TCO layer directly on the silicon semiconductor wafer. Using an inkjet printing process should make the entire manufacturing process faster and more flexible.