Light-Trapping Structure for Solar Cells Based on Boehmite Nanosheets

Current crystalline silicon (c-Si) solar cells typically employ pyramidal texturing and a silicon nitride (SiNx) film to suppress light reflection and improve the power conversion efficiency (PCE). However, appreciable reflection persists at both short and long wavelengths, indicating that further optical optimization is possible. Here, we introduce a boehmite nanosheet layer onto c-Si solar cells by leveraging the refractive index mismatch at the SiNx/air interface. Together with the pyramidal texture, the nanosheets form a micronano-composite structure with a graded refractive index. This architecture reduces the weighted-average reflectivity (300–1100 nm) from 4.66% to 3.80%, increases the short-circuit current density by 0.26 mA cm–2, and improves the PCE by 0.18%. The method provides a low-cost route to add an auxiliary antireflection layer to existing c-Si architectures, enhancing both short- and long-wavelength responses and potentially extending to other solar-cell technologies.