Excitons and Interband Excitations in Conducting Polymers Based on Phenylene

A microscopic model for the photoexcitations of polyphenylenes is introduced. It allows for the effects of the "correlation-energy gap" $U$ between charged and charge-neutral excitations and the dipole-dipole interaction $V$ between neighboring monomers. It leads to the generic appearance of three dispersing absorption bands whose relative spacings in energy are largely set by $U$ and the electronic bandwidth $W$, thereby establishing direct experimental access to these microscopic parameters.