U.S. Department of Energy’s National Renewable Energy Laboratory has
claimed a new world record for copper indium gallium diselenide (CIGS)
thin-film solar cell conversion efficiency of 19.9 percent. In 1994,
NREL researchers had touted CIGS cell efficiencies of only 11 percent.
The conversion efficiency for CIGS is now close to that of
multicrystalline silicon-based solar cells, according to NREL.
“This is an important milestone,” said NREL Senior Scientist Miguel Contreras. “The thin film people have always looked for matching silicon in performance, and we are reaching that goal.”
NREL researchers said that the new efficiency levels were achieved by improvements in the quality of the thin-film materials applied to the substrate. Thin-film cells require less energy to make and can be fabricated by a variety of processes, NREL said.
According to NREL’s own research, 10 different deposition methods for growing the thin CIGS absorber layers are currently used by thin-film PV manufacturers. Molybdenum is used for the back contact deposited by sputtering, while the majority of manufacturers use zinc oxide as the front contact deposited either by sputtering or chemical vapor deposition techniques.