Photoelectrical transport in in-plane and sandwich thin film devices was experimentally studied. Multilayer Langmuir-Blodgett corbathiene (CRB) films and regio-regular poly(3-dodecylthiophene) (PDDT) cast films were subjected to the studies. Indium tin oxide (ITO), n-Si, p-Si, Al and Au electrodes were used in the devices. Using different electrode combinations it was possible to observe linear as well as rectifying device characteristics. Hole injection into the films was found to be responsible for the current passing through interfaces, and film resistivity for the current passing through the bulk film. A highly pronounced photoconductivity signal was observed corresponding to light absorption at the film/n-Si substrate interface. Photoconductivity was also observed under the conditions when photoinduced carriers were generated in the bulk film. The data are compared for the two types of the films used, and interpreted in terms of the energy bands diagrams of the devices and chemical interface formation by π-conjugated system and n-Si surface.