Optical modelling for multilayer and geometric light-trapping structures for crystalline silicon solar cells

The use of thinner wafers, new anti-reflection coating materials and rear passivation layers make necessary a generalized, flexible optical model that can simulate a wide wavelength range without excessive computation time and complexity. This paper presents an optical model based on the transfer matrix method. The crystalline silicon wafer with dielectric layers on both sides is modeled as an incoherent layer between coherent multilayer dielectric structures. In addition, an incident angle distribution from a geometric analysis was also used to extend the application of the model to textured surfaces. The model was validated by comparing simulated and experimental reflectance for a number of alkaline-textured surfaces including the coating materials of silicon nitride and anodic aluminum oxide (AAO). It was used to estimate that the optimum thickness for an AAO ARC was 100 nm and to predict the optimum (optical) combination of thicknesses of dielectric layers on the rear surface of a crystalline silicon solar cell.