GOLDEN, Colo. - The prospect for lower-cost alternatives to crystalline silicon solar cells brightened considerably when the U.S. Department of Energy’s (DOE’s) National Renewable Energy Laboratory (NREL) announced that it has created a thin-film solar cell with a record efficiency.

NREL created the solar cell from thin films of semiconducting materials made from alloys of cadmium, indium, copper, and selenium, or CIGS. The cell achieved a record thin-film conversion efficiency of 19.9 percent, that is, the cell is able to convert 19.9 percent of the sunlight hitting it into electricity. Although solar cells have been built with much higher efficiencies using expensive processes and multiple layers of semiconductors, the more common crystalline silicon solar cells have achieved at most efficiencies of 20.3 percent, which is quite close to the NREL achievement with the thin-film CIGS solar cell.

CIGS solar cells use extremely thin layers of semiconductor material applied to a low-cost backing such as glass, flexible metallic foils, high-temperature polymers, or stainless steel sheets. Thin-film cells require less energy to make and can be fabricated by a variety of processes. Because of this, they provide a promising path for providing more affordable solar cells for residential and other uses.

Publication date: 03/31/2008