Photogeneration of charge carriers in organic superlattices with polarization double barriers

At the interface of molecular organic solids with largely different polarization energies, P the polarization double barrier (PDB) is shown to appear in electronic band structure. Contrary to conventional p-n junctions the PDB has a symmetric effect both on electrons and holes on each side of the interface. PDB originates from the opposite changes of the band gaps in each molecular layer and is estimated to be sizable at the interface between molecules like rubrene and p-iodanil. Photogeneration of charges might be enhanced due to better dissociation of molecular excitons at lower side of PDB, and selective injection of charges into adjacent layers. In organic multilayered superlattices of “fullerene-conducting polymer” (CP) type this may increase the photoseparation of charges between layers of C60 and CP leading to strongly anisotropic photoconductivity and to enhanced photovoltaic effect in multilayered photocell geometry.