University of Southern California (USC) scientists have developed a method to produce stable, low-cost solar cells from nanocrystals. These cells can be printed or painted onto surfaces as they are in the form of a liquid ink. These solar nanocrystals can float in a liquid solution and measure around 4 nm.
Assistant professor of chemistry, Richard L. Brutchey, and David H. Webber, a postdoctoral researcher at the USC Dornsife College of Letters, Arts and Sciences, have jointly developed a novel surface coating made of cadmium selenide for the nanocrystals. The study was published in Dalton Transactions, an international journal for inorganic chemistry.
Liquid nanocrystal solar cells have advantages and disadvantages when compared to single-crystal silicon wafer solar cells. Wafer solar cells have a higher efficiency in converting sunlight to electricity, whereas liquid nanocrystal solar cells can be fabricated at a lower cost. The researchers discovered a method to create liquid solar cells that can also conduct electricity effectively.
In order to maintain the stability of nanocrystals, organic ligand molecules were used. These molecules were connected to the nanocrystals. They prevented the nanocrystals from sticking together. As this led to insulation, conduction of electricity was affected.
The researchers found a synthetic ligand that was capable of building bridges for connecting nanocrystals. This helped increase the conductivity of the nanocrystals.
The method developed by the researchers enables printing of solar cells onto plastic, leading to the possibility of flexible solar cells. Further, as cadmium is toxic, the researchers plan to create nanocrystals from other materials.