On the use of local ideality factor obtained from effective carrier lifetime measurements

Assessing the local ideality factor m is a useful approach to identify performance-limiting mechanisms in solar cells. Typically, m is extracted from the current-voltage curve of a completed solar cell and plotted as a function of voltage. In this study, m is extracted from photoluminescence measurements of the effective carrier lifetime and plotted against the minority carrier concentration Δn or the implied open-circuit voltage V_{oc i}. It is shown that a plot of m(Δn) [or m(V_{oc i})] is a powerful way to analyze recombination processes within a silicon wafer, where its main advantage is that it can be determined from wafers that have neither metal contacts nor a p-n junction.