ELECTRONIC-STRUCTURE OF PI-CONJUGATED ARYLENE ETHYNYLENE POLYMERS

We investigate theoretically the geometric and electronic structure of pi-conjugated poly(arylene ethynylene) polymers: C drop C-Ar-C drop C -Ar')(n), where Ar and Ar' correspond to a pyridinylene or a phenylene and a thienylene moiety, respectively. It was recently observed that these polymers present a large third-harmonic-generation response as w ell as strong photoluminescence; the latter feature indicates that the y are potentially good candidates as active materials in electrolumine scent devices. Geometry optimizations are carried out at the AM1 level , whereas the electronic properties are derived from valence-effective Hamiltonian calculations. We also simulate the whole UV-Vis optical a bsorption spectra of the oligomers on the basis of an INDO configurati on interaction approach.