The Photoconductivity of Anthracene. I.

Pure crystals of anthracene became photoconducting when illuminated with wavelengths lying within their fundamental absorption band. The majority carriers were positive holes, which, as they drifted through the crystal, took part in trapping processes. From the variation of the photocurrent with temperature it was concluded that the number of positive hole traps fell off exponentially as their height above the valence band increased. From the behavior of the photocurrent at various applied fields and light intensities, it was concluded that the conventional energy band diagram as used for inorganic substances could be applied to organic compounds also. Evidence was found, however, indicating that there were large potential irregularities in the energy levels throughout the crystal.