3D Optical Simulation of Scattering in Thin Film Silicon Solar Cells
Efficient light trapping is of great importance for thin-film silicon solar cells. Randomly textured TCO or glass substrates provide excellent light trapping and are frequently applied. Optical simulation of such textures is challenging due to a large variety of occurring geometrical features. In this paper we suggest an approach for the 3D optical simulation of scattering structures. This approach is based on a simulation and investigation of the constituting single structure features and subsequent implementation of the solar cell structure into the rigorous coupled wave analysis (RCWA). In this paper we present first results of this method for a microcrystalline silicon solar cell deposited on a sputtered and etched ZnO surface. The simulated absorption for the single structures is compared to quantum efficiency measurements on large areas. Good agreement between simulation and measurement is found. Comparing periodic and random structures, we find that small periodic structures can increase the absorbed photocurrent density by up to 3 mA/cm2. The best result was obtained for a structure with a diameter of D = 800 nm.