Imagine a solar cell that comes in a jar instead of a big, clunky panel, and that could be painted on a piece of plastic. It might be closer than you think - scientists at the University of Southern California have developed a new type of solar cell made from nanocrystals that are so small that you could fit about 250 billion of them on the head of a pin. Due to their size, the nanocrystals can be made into an ink and painted or printed onto clear surfaces. The breakthrough could open the door to solar cells that can be printed onto plastic instead of glass, and then bent and shaped to fit anywhere.
Liquid nanocrystal solar cells are cheaper to produce than traditional single-crystal silicon wafer solar cells, but they don’t convert sunlight to electricity as efficiently. Previous attempts to develop liquid solar cells have used organic ligand molecules to to keep nanocrystals stable and to prevent them from sticking together. But the ligand molecules were poor conductors of electricity, and they hurt the efficiency of the solar cells. To overcome that problem, the USC scientists developed a synthetic ligand that builds tiny bridges connecting the nanocrystals to help transmit current.
The new surface coating for the nanocrystals is made of the semiconductor cadmium selenide, which can’t be used commercially because of its toxicity. “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,” USC chemistry professor Richard L. Brutchey said in a press release. The USC researchers now plan to work on building nanocrystals using materials other than cadmium.
Photos by Dietmar Quistorf / USC