On the Electrical Conductivity of the Organic Thin Films: Perylene, Coronene and Violanthrene

It was found that the various types of conductivity cells of aromatic hydrocarbons possess great discrepancies of their electrical resistivity. The resistivity observed with the sandwich-type cell, perylene; 1018∼19 Ωcm., coronene; 1017∼18 Ωcm., and violanthrene; 1014 Ωcm., is in quite good agreement with that of the bulk specimen. However, a great difference was found between the resistivities of the sandwich-type and the surface-type cells, perylene; 1013 Ωcm., coronene; 1012∼13 Ωcm., and violanthrene ; 109 Ωcm. This discrepancy in resistivity can be assumed to be introduced from the textured structure of the evaporated films and the substantial anisotropy of crystals; the crystals are in alignment with their a·b plane with the film surface. This orientation was found from the X-ray diffraction results, combined with the electron microscopic observation and the electron microdiffraction results.