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.