Light trapping effect of submicron surface textures in crystalline Si solar cells

Recently, submicron textures have been researched and applied to multicrystalline silicon solar cells in order to improve their optical performance. In this study, the antireflection and light trapping effects of submicron surface textures in crystalline Si (c-Si) solar cells were quantitatively investigated by numerical simulations based on Maxwell's equations with a simple two-dimensional (2D) surface grating model. The calculated results showed that the surface reflection loss can be effectively reduced by using submicron Si surface gratings with appropriate aspect ratios. On the other hand, higher order diffractions that are caused by surface gratings that increase optical path lengths and light absorption near the band gap wavelength are dominant only for those with periods greater than 0-5 μm. From these results, it was inferred that submicron textures are effective for light trapping as well as for antireflection in thin c-Si solar cells if appropriate dimensions are chosen.