IMPROVEMENTS IN ANTIREFLECTION COATINGS FOR HIGH-EFFICIENCY SILICON SOLAR-CELLS

This paper summarizes a theoretical and experimental optimization of s everal anti-reflection structures for crystalline silicon solar cells. Cases using SiO2, a Ta2O5 single layer and a MgF2-ZnS double layer ov er polished surfaces are compared. The optimization was performed usin g reflection curves and short-circuit current densities obtained from each of the analyzed structures. The optimization procedure was perfor med as follows: (1) optimizing the thickness and reflection curve of t he theoretical structure and (2) obtaining the reflectivity of the clo sest experimental anti-reflection coating. A very low experimental ref lection was observed for the double layer. An experimental short-circu it current density of 37.03 mA cm(-2) was obtained for the MgF2-ZnS do uble layer, while for Ta2O5 and SiO2 single layers the results were 34 .84 and 33.00 mA cm(-2), respectively. These results were compared wit h a maximum short circuit current density of 38.70 mA cm(-2), for a st andard solar cell with no reflection. The reflection curves and short circuit current densities of the double layer are less sensitive to va riations in thickness as compared to those of the single layers. (C) 1 998 Elsevier Science S.A.