One material system of interest for photovoltaic cells is the combination of the p-conducting copper-phthalo-cyanine
(CuPc) and the n-conducting fullerene (C60) as donor and acceptor materials, respectively. Therefore the
transport properties for diodes containing neat and blended organic films are analysed in the space charge limited
current regime. The charge carrier mobilities are found to decrease upon dilution of the respective conducting
phase by the other species. Photovoltaic cells can be realised with bilayered or blended organic donor/acceptor
films. The influence of both photo-active layer types on the electronic structure and the open circuit voltage is
investigated. From photoelectron spectroscopy a higher open circuit voltage is predicted for bilayered solar cells.
Due to mixing of the organic materials the intermolecular gap between the highest occupied molecular orbital
of the donor and the lowest unoccupied molecular orbital of the acceptor is reduced. This prediction is proven
true by photocurrent measurements.