Electronic Properties of Quaterrylene, C40H20

Quaterrylene (C40H20) is a dark green-coloured aromatic hydrocarbon and is extraordinarily stable, as it can be heated to over 500°C without decomposition. The semiconduction of the aromatic hydrocarbon possesses a substantial anisotropy by a factor of 107∼108; the resistivity in the direction parallel to the b axis is 106Ωcm. (for a single crystal) or 105Ωcm. (for a surface-type cell) and that perpendicular to the b axis is 1013Ωcm. However, their energy gaps are around 0.6 eV. From its pulsed photoconduction of the thin film, a drift mobility has been estimated in the order 10−3 cm2/V. sec. However, the rectifying effect of the photoconduction can scarcely be recognized; that is to say, it seems that the mobilities of the holes and electrons in crystal are almost the same. Further, its photovoltage between aluminium and quaterrylene has a value of 0.1∼0.3 V., while the ionization potential of the hydrocarbon is 4.9 eV. judging from the threshold value of the spectral response of the photoelectric emission. From these results, a energy level diagram has been introduced for the system of the aromatic hydrocarbon-aluminium contact when a band-type model is employed as the organic semiconductor.