The electronic structure of polyphenyls and poly(p-phenylene)

Abstract

The ultraviolet photoemission, optical absorption, and core-level shakeup spectra of p-phenylene oligomers and poly(p-phenylene) are analyzed using the spectroscopically parametrized CNDO/S3 model. The densities of valence states are calculated for these molecules and shown to provide a good description of available photoemission spectra. Photogenerated radical cation states can be delocalized over four or more phenyl moieties in the solid-state oligomers. The relationship between the density of valence states and the energy band structure of macromolecules of poly(p-phenylene) is established. The energies of the lowest energy electronic excitations of p-phenylene oligomers are evaluated and shown to describe well the available UV absorption and XPS shakeup measurements. The influence of disorder in the solid state is assessed by analysis of the influence of macromolecular conformation on the electronic structure.