SCIENCE IN THE NEWS DAILY
Solid Advance for Cheap Solar Cells
from ScienceNOW Daily News
The price of solar cells has been gliding downward for decades. Now this trend could get a shove from an improvement to a more than 20-year-old solar technology that captures light with dye molecules, an approach that's never managed to catch on. The advance is "one of the most important breakthroughs in dye cells in the last several years," says Thomas Mallouk, a chemist at Pennsylvania State University, University Park, who was not involved in the study.
Eighty percent of the market for solar cells is taken up by cells made from crystalline silicon wafers, which convert about 20% of the energy in incoming sunlight into electricity. Most of the rest of the market consists of "thin film" cells made from different semiconducting alloys that can be cheaper to produce but require toxic or rare elements.
A third class of solar cells, first developed in 1991 by researchers in Switzerland, are the cheapest to make and are more than 12% efficient. These cells, known as dye-sensitized solar cells (DSSCs), consist of millions of tightly packed titanium dioxide nanoparticles, each coated by a single layer of dye molecules. The titanium dioxide-dye combo is then bathed in an electrically conductive liquid containing mobile ions called an electrolyte.