Abstract

The rigorous coupled-wave approach (RCWA) is extensively used to compute optical absorption and photon absorption in thin-film photovoltaic solar cells backed by 1D metallic gratings when the wave vector of the incident light lies wholly in the grating plane. The RCWA algorithm converges rapidly for incident ????s-polarized light over the entire 400–1100 nm solar spectrum. It also performs well for incident ????p-polarized light in the 400–650 nm spectral regime, but even with a large number of Floquet harmonics in the solution, the total reflectance is underestimated in the 650–1100 nm spectral regime. Despite that shortcoming, the RCWA underestimates the solar-spectrum-integrated photon absorption rate only by 5%–10% for ????p-polarized light. As sunlight is almost unpolarized, the RCWA should be considered adequate to design thin-film silicon solar cells with periodically corrugated metallic backreflectors