Carrier mobility is a key parameter for the application of conjugated polymers. In this work, a series of polyfluorenes (PF2/6) with different fractions of crosslinkable acrylate groups is investigated. Mobility measurements are carried out to assess the influence of crosslinking with different photoinitiators on the performance of the material. For the regime of low to medium charge carrier density, relevant for OLEDs and OPVs, we used a novel technique based on the injection of charge carriers from the electrodes of an optoelectronic device: MIS-CELIV (MIS: metal-insulator-semiconductor). For large charge carrier densities we performed OFET measurements. We find that using optimized conditions crosslinking does not influence the hole mobility in the investigated system. Furthermore, we demonstrate that the crosslinking process may be triggered solely by thermal activation and UV-illumination without the need of any initiator. Thus, densely crosslinked networks are obtained without the formation of undesired decomposition products from added photoinitiator. (c) 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017, 55, 112-120