An ultrathin solar cell relies on a nanostructured back mirror to achieve an efficiency of almost twenty percent.
Typically, gallium arsenide-based solar cells require a semiconductor material at least one micrometer thick, which is required for adequate light absorption. However, a new process from the teams at Fraunhofer and the Center for Nanoscience and Nanotechnology slims the solar cells even more while also increasing efficiency. The key to the technology is a nanostructured back mirror that creates overlapping resonances in the solar cell that trap light in the absorber while also improving optical absorption.
According to the research team, “Controlling the fabrication of patterned mirrors at the nanometer scale was a key in the project.” The team believes the cell’s efficiency could be increase to as much as 25 percent and the cells could be slimmed down even more.