MOLECULAR-ORBITAL CALCULATIONS OF ELECTRONIC EXCITED-STATES IN POLY(P-PHENYLENE VINYLENE)

The electronic structures of model oligomers (monomers, dimers,..., he xamers) of poly(p-phenylene vinylene) were studied using the intermedi ate neglect of differential overlap method with spectroscopic parametr ization (INDO/S). The calculated first singlet-to-singlet transitions compare favorably with the experimental spectra. The results from the exciton theory are also presented. Our results show that the conjugati on length is finite and the interactions between polymer chains play a very important role in optical properties. The theoretical results fo r the triplet-to-triplet transitions are in accord with the experiment al values, supporting the experimentally ascribed triplet-to-triplet p hotoinduced absorption feature in oligomers.