Perylene- and phthalocyanine-pigment molecules were systematically modified and consequences were studied for their solid state properties. Thin films (1- 100 nm) of these compounds were prepared by physical vapor deposition on Si- based interdigitated microelectrode arrays or transparent insulating substrates such as (amorphous) glass or (single crystalline) alkali halides. Intermolecular interactions were probed by optical measurements in absorption and emission as well as by measurements of the electrical conductivity and the field effect (OFET). The morphology of films was studied by transmission electron microscopy (TEM) and atomic force microscopy (AFM).Different interactions among the molecules and with the substrate surfaces allowed to prepare either crystalline or amorphous films. Crystalline films were characterized by strong chromophore coupling leading to characteristic splitting, well- defined shifts of optical absorption bands and emission mainly from excimeric species whereas the chromophore coupling in the amorphous films was suppressed sufficiently to provide a significantly increased photoemission yield from uncoupled monomeric states.