A Laser‐Processed Silicon Solar Cell with Photovoltaic Efficiency in the Infrared

Abstract

Hyperdoped and textured silicon created with a femtosecond laser in the presence of SF 6 gas has a highly absorbing surface with extended spectral sensitivity in the infrared. The main drawback of this micro‐ and nanostructured material for photovoltaic (PV) cells is an increase in charge‐carrier recombination at the surface due to the typically poor crystallinity of the surface layer. Laser annealing postprocessing of the black silicon (b‐Si) surface is used to greatly reduce the crystal structure defects while maintaining sub‐bandgap absorption. The back side of the cell is functionalized with spin‐on doping and laser fired contacts to make an interdigitated back‐contact proof‐of‐concept b‐Si solar cell. It is shown that this cell has measurable PV efficiency in the sub‐bandgap infrared, a promising step toward developing intermediate‐band silicon PVs.