Friday, April 27, 2012

#ENERGY: "Nanocrystalline Printable Solar Cells Maturing"

The promise of ultra-cheap solar cells that can be printed like ink on almost any surface got closer to realization recently, according to researchers at the University of Southern California. USC claims its scientists that nanocrystals of cadmium selenide in a liquid vehicle can be printed onto polymers with a new kind of highly conductive ligand that should now make the technique commercially feasible.
R. Colin Johnson

A USC scientist treats a glass slide with nanocrystals. (Photo/Dietmar Quistorf)

Here is what USC says about their researcher breakthrough: Scientists at USC have developed a potential pathway to cheap, stable solar cells made from nanocrystals so small they can exist as a liquid ink and be painted or printed onto clear surfaces.

Richard Brutchey, assistant professor of chemistry at the USC Dornsife College of Letters, Arts and Sciences, and USC postdoctoral researcher David Webber developed a new surface coating for the nanocrystals, which are made of the semiconductor cadmium selenide.

Liquid nanocrystal solar cells are cheaper to fabricate than available single-crystal silicon wafer solar cells but are not nearly as efficient at converting sunlight to electricity. Brutchey and Webber solved one of the key problems of liquid solar cells: how to create a stable liquid that also conducts electricity.

In the past, organic ligand molecules were attached to the nanocrystals to keep them stable and to prevent them from sticking together. These molecules also insulated the crystals, making the whole thing terrible at conducting electricity.

Brutchey and Webber discovered a synthetic ligand that not only works well at stabilizing nanocrystals but actually builds tiny bridges connecting the nanocrystals to help transmit current.

With a relatively low-temperature process, the researchers’ method also allows for the possibility that solar cells can be printed onto plastic instead of glass without any issues with melting, resulting in a flexible solar panel that can be shaped to fit anywhere.

As they continue their research, Brutchey said he plans to work on nanocrystals built from materials other than cadmium, which is restricted in commercial applications due to toxicity.

The National Science Foundation and USC Dornsife funded the research.
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