Influence of texture feature size on the optical performance of silicon solar cells

Textured silicon solar cells have been generally studied in the geometrical optics approximation. This description predicts no dependence of reflectance or other optical properties on the size of the texture pyramids. In this work textures are represented as two-dimensional periodic diffraction gratings and their optical properties are analyzed with rigourous numerical methods. It is concluded that reflectance significantly increases with respect to the geometrical optics limit for pyramid sizes smaller than around 300 nm. Besides, for small pyramids the light transmitted into the substrate is not tilted with respect to the normal to the surface. Additional calculations are made to assess the effect of the random distribution of the pyramids.