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

The electronic structures of model oligomers (monomers, dimers,..., hexamers) of poly(p-phenylene vinylene) were studied using the intermediate neglect of differential overlap method with spectroscopic parametrization (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 conjugation length is finite and the interactions between polymer chains play a very important role in optical properties. The theoretical results for the triplet-to-triplet transitions are in accord with the experimental values, supporting the experimentally ascribed triplet-to-triplet photoinduced absorption feature in oligomers.