Advanced characterization of multijunction solar cells with electroluminescence

Characterization is a key process in attaining high efficiency in state-of-the-art multijunction solar cells. However, the characterization of these devices using methods involving optical excitation and measurements of optical response is challenging and time consuming. For instance the experimental access to information about individual subcells is difficult to attain with common methods. This work will present how the characterization of these devices benefits from the use of electroluminescence spectroscopy (EL). In this study we use a low cost EL set-up -which could be easily integrated in any in-line characterization tool at a manufacturing site-to derive the individual performance of each subcell in the multijunction stack. Using electroluminescence measurements, the external quantum efficiency of each subcell, the current-voltage curve of each subcell and the individual quality factors of each subcell are calculated.