Electroabsorption studies of phthalocyanine/perylene solar cells

We report electroabsorption (EA) studies of electric fields in bilayer mole cular organic solar cells made from zinc phthalocyanine (ZnPc) and a methyl substituted perylene pigment (MPP). We have detected an electric field at the metal/organic interface which is sensitive to the external DC bias. The interface field has a different spectral signature from that of the bulk o f the two layers, which we attribute to interface species such as charge tr ansfer-induced dipoles. The electric field is proportional to the applied b ias in devices containing only ZnPc or MPP, but rectifying behavior is obse rved in the bilayer solar cell. (C) 2000 Elsevier Science B.V. All rights r eserved.