Advanced Series Resistance Imaging for Silicon Solar Cells via Electroluminescence

Herein, a method for advanced series resistance imaging via electroluminescence (EL) for silicon solar cells is presented. The well-known method by Haunschild et al. is revisited. The Fuyuki assumption of a linear relation between diffusion length and EL signal is shown to be not applicable to silicon devices nowadays due to larger minority charge carrier diffusion lengths and thinner solar cells. A new relation derived by Breitenstein is used here instead. The updated method for series resistance and saturation current imaging based on two EL images, which show a far superior separation of contrast and almost 60% shorter data acquisition times in comparison with the original method by Haunschild, is presented. The Weber contrast of the unwanted signal caused by recombination in resistance image is reduced from 0.89 to 0.44, using the advanced method for a prominent feature on the sample cell. The contrast due to resistance stays at the same level. The dark saturation current density images show 20% higher peaks at recombination active areas and also a 5% low.