Forward and inverse design of single-layer metasurface-based broadband antireflective coating for silicon solar cells

Almost half of the solar energy that reaches a silicon solar cell is lost due to the reflection at the silicon–air interface. Antireflective coatings aim to suppress the reflection and thereby to increase the photogenerated current. The conventional few-layer dielectric antireflective coatings may significantly boost the transmission of solar light, but only in a narrow wavelength range. Using forward and inverse design optimization algorithms, we develop the designs of antireflective coatings for silicon solar cells based on single-layer silicon metasurfaces (periodic subwavelength nanostructure arrays), leading to a broadband reflection suppression in the wavelength range from 500 to 1200 nm for the incidence angles up to 60 deg. The reflection averaged over the visible and near-infrared spectra is at the record-low level of approximately 2% and 4.4% for the normal and oblique incidence, respectively. The obtained results demonstrate the potential of machine learning–enhanced photonic nanostructures to outperform the classical antireflective coatings.