Extended FF and V _OC Parameterizations for Silicon Solar Cells

This work is concerned with maximal and currently obtained fill factors of crystalline silicon solar cells. Recent research activities have led to a drastically decreased recombination in the volume as well as at the surfaces and interfaces of crystalline silicon solar cells. As a result, open-circuit voltages $( {{V}_{\text{OC}}} )$ and fill factor $( {\textit{FF}} )$ values increased significantly. In order to classify how good the achieved improvements are, it is necessary to know the maximum achievable values. Unfortunately, there is no explicit expression for the ${\textit{FF}}$ in terms of other characteristic solar cell parameters. For this reason, the empirical ${\textit{FF}}_{0}$ -relation by Green is widely used to predict upper ${\textit{FF}}$ bounds for a given ${V}_{\text{OC}}$ . In order to evaluate to what extent Green's relation is a good approximation to recently obtained values, we study ${\textit{FF}}$ – ${V}_{\text{OC}}$ relations for ideal resistance-free single junction silicon solar cells limited by intrinsic recombination using state-of-the-art analytical models. The obtained upper bounds are compared with recently published record values showing that all values stay below the intrinsic limit. We provide parameterizations of ${V}_{\text{OC}}$ and ${\textit{FF}}$ as a function of sample thickness w and base dopant density ${N}_{\text{dop}}$ .