The addition of small amounts of dodecylamine-capped Au nanoparticles into the active layer of organic bulk heterojunction solar cells consisting of poly(3-octylthiophene) (P3OT) and C-60 was recently suggested to have a positive impact on device performance due to improved electron transport. This issue V,was systematically further investigated in the present work. Different strategies to incorporate colloidally prepared Au nanoparticles with a narrow size distribution into organic solar cells with the more common donor/acceptor system consisting of poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C-61-butyric acid methyl ester (PCBM) Were pursued. Au nanoparticles were prepared with either P3HT or dodecylamine as ligands. Additionally efforts were undertaken to incorporate nearly ligand-free AIL nanoparticles into the system. Therefore, I procedure was successfully developed to remove the dodecylamine ligand shell by a postpreparative ligand exchange with pyridine, a Much smaller molecule that call later partly be removed from solid films by annealing. However, for all types of nanoparticles Studied here, the performance of the P3HT/PCBM solar cells was found to decrease With the Au particles as in additive to the active layer, meaning that adding Au nanoparticles is not a suitable strategy in the case of the P3HT/PCBM systern. Possible reasons are discussed oil the basis of detailed investigations of the structure, photophysics and charge transport in the systern.