Solar energy : Seeing red
To make solar cells more efficient, sprinkle them with silver
Source: The Economist, Jan 8th 2009
http://www.economist.com/science/displaystory.cfm?story_id=12887225
MAKERS of solar cells face a dilemma. Purified silicon, the basic material of such cells, is expensive. The temptation, therefore, is to use less of it. As a result, the makers have developed a generation of cells whose silicon layers are only a micron or two deep, as opposed to the usual thickness of 200-300 microns. The thinner the cell, however, the less efficient it is. In particular, thin cells fail to capture much light at the red end of the spectrum. That means they produce up to 20% less electricity than standard cells of equivalent area. And that negates some of the advantage of their initial cheapness. (more…)