Improvements in anti-reflection coatings for high-efficiency silicon solar cells

This paper summarizes a theoretical and experimental optimization of several anti-reflection structures for crystalline silicon solar cells. Cases using SiO2, a Ta2O5 single layer and a MgF2-ZnS double layer over polished surfaces are compared. The optimization was performed using reflection curves and short-circuit current densities obtained from each of the analyzed structures. The optimization procedure was performed as follows: (1) optimizing the thickness and reflection curve of the theoretical structure and (2) obtaining the reflectivity of the closest experimental anti-reflection coating. A very low experimental reflection was observed for the double layer. An experimental short-circuit current density of 37.03 mA cm-2 was obtained for the MgF2-ZnS double layer, while for Ta2O5 and SiO2 single layers the results were 34.84 and 33.00 mA cm-2, respectively. These results were compared with a maximum short circuit current density of 38.70 mA cm-2, for a standard solar cell with no reflection. The reflection curves and short circuit current densities of the double layer are less sensitive to variations in thickness as compared to those of the single layers.