Light Trapping and Carrier Lifetime Improvements of Si Solar Cells by Pyramid/Groove Hierarchical Structures

The textured surface of silicon wafer plays an important role in solar cell to reduce surface reflection, enhance light trapping and thereby improve conversion efficiency. Conventionally, the microstructures are usually achieved in commercial solar cells by isotropic and anisotropic wet etching. However, these structures still reflect about 14% incident light. In contrast, the nanostructures can suppress the reflectance as low as 5% but they easily cause the low carrier lifetime.To break the trade-off between low reflectance and high carrier lifetime for boosting the conversion efficiency of the solar cells, this study combines isotropic and anisotropic wet etching methods in texturing silicon surface, making a hierarchical microstructure consisting of grooves and pyramids and improving the efficiency of the Heterojunction with Intrinsic Thin layer (HIT) solar cells to 12.47%.