|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