Cheap, durable, efficient devices are needed to generate a significant amount of electricity from the sun. So-called thin-film photovoltaic cells may be just the ticketThe sun blasts Earth with enough energy in one hour—4.3 x 1020 joules—to provide all of humanity's energy needs for a year (4.1 x 1020 joules), according to physicist Steven Chu, director of Lawrence Berkeley National Laboratory. The question is how to most effectively harness it. Thin-film solar cells may be the answer: One recently converted 19.9 percent of the sunlight that hit it into electricity, surpassing the amount converted into power by mass-produced traditional silicon photovoltaics and offering the potential to unleash this renewable energy source.
Prices for high-grade silicon (that can generate electricity from sunlight) shot up in 2004 in response to growing demand, reaching as high as $500 per kilogram (2.2 pounds) this year. Enter thin-film solar cells—devices that use a fine layer of semiconducting material, such as silicon, copper indium gallium selenide or cadmium telluride, to harvest electricity from sunlight at a fraction of the cost. More>>>
