Scientists at the University of Southern California have developed new solar cells in the form of a liquid that can be painted or printed onto clear surfaces. The new technology is cheap to produce and relies on stable solar nanocrystals that are only four nanometers in size, which is so small you could fit 250 billion on the head of a pin. These particles are then suspended in liquid like pigment and can be printed like ink.
The liquid solar cell technology can be implemented under a low-temperature process, which means that it can be printed on plastic instead of glass without concern of the plastic melting. This would allow for cheap, flexible solar panels and more options in applying the solar technology.
Although the new liquid solar nanocrystals are cheaper than traditional single-crystal silicon wafer solar cells to produce, they are also much less efficient. In order to keep the particles stable, organic ligand molecules are used to attach to the nanocrystals to keep them from clumping, but in effect, also insulates them and reduces their conductivity.
Additionally, the current nanocrystals used are made of the semiconductor cadmium selenide, which is considered toxic and is restricted in commercial applications. The researchers are still working on alternative materials for the nanocrystals. Hence, it will still be a few years before we see this technology in commercial use.