RECTIFYING JUNCTIONS IN PERIPHERALLY-SUBSTITUTED METALLOPHTHALOCYANINE BILAYER FILMS

Thin bilayer films formed by the sequential vapor deposition of two different peripherally-substituted metallophthalocyanines exhibit rectifying behavior toward an applied dc voltage. The degree of rectification is shown to be enhanced in the presence of oxygen. These bilayer films demonstrate that device activity can be imparted to a phthalocyanine junction via ''band tuning'' and represent the first examples of non-Schottky type rectification observed in phthalocyanine-based junctions. Analysis of the forward current-voltage characteristics suggests that a possible Frenkel-Poole carrier detrapping mechanism exists in these systems. Preliminary band structure calculations indicate that the bilayers are actually p-p isotype heterojunctions.