Series resistance mapping of III-V multijunction solar cells based on luminescence imaging

A method for spatially resolved series resistance measurements of Ga_0.5In_0.5P/Ga(In)As/Ge triple-junction solar cells based on electro- and photoluminescence imaging is presented. The results gained from luminescence images of all three subcells clearly indicate the main contributions to the series resistance like interrupted gridfingers, the frontside metallization itself and the top cell emitter layer. Test cells with partially electron irradiated areas are used to demonstrate that the method is not sensitive to inhomogeneous dark I-V parameters.