  A general problem arising in computer simulations is the number of material
and device parameters, which have to be determined by dedicated experiments and
simulation-based parameter extraction. In this study we analyze measurements of
the short-circuit current dependence on the active layer thickness and
current-voltage curves in poly(3-hexylthiophene):[6,6]-phenyl-C61-butyric acid
methyl ester (P3HT:PCBM) based solar cells. We have identified a set of
parameter values including dissociation parameters that describe the
experimental data. The overall agreement of our model with experiment is good,
however a discrepancy in the thickness dependence of the current-voltage curve
questions the influence of the electric field in the dissociation process. In
addition transient simulations are analyzed which show that a measurement of
the turn-off photocurrent can be useful for estimating charge carrier
mobilities.
