Researchers at the US Department of Energy’s National Renewable Energy Laboratory have moved closer to creating a thin-film solar cell that can compete with the efficiency of the more common silicon-based solar cell.

The copper indium gallium diselenide (CIGS) thin-film solar cell recently reached 19.9 percent efficiency, setting a new world record for this type of cell. Multicrystalline silicon-based solar cells have shown efficiencies as high as 20.3 percent. The energy-conversion efficiency of a solar cell is the percentage of sunlight converted by the cell into electricity.

“This is an important milestone,” said Miguel Contreras, NREL senior scientist. “People have always looked for matching silicon in performance [with thin film], and we are reaching that goal.”

CIGS 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. The CIGS cells are suitable in special architectural uses, such as photovoltaic roof shingles, windows, siding and others. Using this technology, a future home’s windows may be able to gather energy as the sun shines through them.