Researchers at the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) were able to squeeze some extra efficiency out of their solar cells through careful design of the materials in the cell stack. Relying on both computational and experimental studies, the scientists grew a gallium arsenide (GaAs) heterojunction solar cell using dynamic hydride vapor phase epitaxy (D-HVPE) with a certified efficiency of 27%, the highest efficiency ever reported for a single-junction GaAs ...