Scientists at the University of Southern California have taken a big step towards the creation of solar cells in the form of a liquid ink that can be painted or printed onto clear surfaces.
Liquid nanocrystal solar cells are cheaper to fabricate than current single-crystal silicon wafer solar cells - but aren't nearly as efficient at converting sunlight to electricity.
Previous efforts have involved attaching organic ligand molecules to the nanocrystals to keep them stable and to prevent them from sticking together. All well and good - except that these molecules also insulate the crystals, making the cells terrible at conducting electricity.
Now, though, the USC team has discovered a synthetic ligand that not only works well at stabilizing nanocrystals, but actually builds tiny bridges connecting the nanocrystals to help transmit current.
Because the process used is relatively low-temperature, the solar cells can be printed onto plastic instead of glass, resulting in a flexible solar panel that can be shaped to fit anywhere.
So far, the team's worked with nanocrystals made of the semiconductor cadmium selenide; the next move is to look at using materials other than cadmium, which is restricted in commercial applications because it's so toxic.
"While the commercialization of this technology is still years away, we see a clear path forward toward integrating this into the next generation of solar cell technologies," says assistant professor of chemistry Richard Brutchey.