PHOTOCONDUCTIVITY OF SOME POLYNUCLEAR AROMATIC HYDROCARBONS

Abstract

The spectral response, voltage dependence, and intensity dependence of the surface photocurrent in naphthalene, terphenyl, pyrene, stilbene, and azulene have been measured. Pyrene and naphthalene have a high sensitivity for photoconduction at the long-wavelength edge of the optical absorption spectrum. In the spectral response of pyrene three peaks appear at 4475 Å, 4275 Å, and 4100 Å. It is suggested that these peaks are due to weak optical absorptions to energy levels which are highly efficient in promoting conduction. It is possible that a similar effect occurs in naphthalene, where maximum photoconductivity coincides with a weak absorption reported by McClure and Schnepp. Azulene only shows photoconductivity at wavelengths corresponding to absorption to the second singlet state.