Rectifying organic junctions of molecular assemblies based on perylene ion salts

Abstract

Using a solid-state diffusion technique, conducting perylene radical ion salt films have been prepared with alkali ions (Na+ and K+) and antimony hexachloride (SbCl6−) as counter ions. The successful preparation of separate radical anion salt films and cation salt films, respectively, is proved by in situ absorption spectroscopy, conductivity measurements, and electron spin resonance. In contrast to comparatively weakly doped inorganic semiconductors, the ion salts have a high concentration of charge carriers of roughly one charge per molecular unit entailing correlation of the carriers. The sandwich structures consisting of both the cation salt layer and the anion salt layer, form an electrical junction comparable to the PIN-junctions (p-doped, intrinsic, n-doped) known from inorganic diodes. The rectifying ratio amounts up to 105:1 at ±0.5 V and the breakdown voltage in the reverse sense is −20 V at 300 K.