Light trapping in monocrystalline Si solar cells using back-side diffraction gratings

摘要

Back-side diffraction gratings enhance a solar cell's near-band-gap response by diffracting light into higher orders and thereby reducing front-side escape losses. The resulting increased photon absorption and carrier generation improves short-circuit current densities and solar cell efficiencies. Combining rigorous coupled-wave analysis and ray tracing yields a three-dimensional, polarization sensitive optical model to calculate Si absorbance, front-side and back-side losses. For industrially used, pyramidally textured, 180 μm Si solar cells with 85 nm SiN_x anti-reflection coating, the application of an optimized back-side grating enhances the short-circuit current density by ≈ +1 mA/cm~2, a relative increase of ≈ +2.7%.