This proposal will study the electrical, fluorescence and non- linear optical properties of conjugated polymers associated with pi-pi* excitations in carbon polymers and sigma-sigma* transitions in polysilanes. Solid-state models for either include electron- phonon and electron-electron interactions in extended Hubbard or Pariser-Parr-Pople models. The proposed studies will exploit exact solutions to quantum cell models, including their non-linear optical responses and extend correlated states to include electron- phonon interactions. The idea is to obtain transferable coupling constants from molecular systems. The different photophysics of polysilanes relative to their carbon counterparts is also central to this proposal. Lastly, new symmetry adapted solutions will be applied to the rich singlet and triplet spectra of anthracene, trans-silbene and other conjugated polymers in order to refine parameters and to study the charge and spin dependence of confined bipolarons and polarons. %%% The idea of this proposal is to get at paramaters which describe the photophysics (eg. fluorescence, conductivity) of polymeric carbon and silicon systems from their simpler molecular fragments. These parameters are used within simple electronic models, which describe the basic quantum mechanical physics of these systems, to determine trends of behavior and the reasons for that behavior. Comparisons between the carbon and silicon analogues will be made. The end result is a better understanding of the spectra of these systems. These materials are of interest because of their large non-linear optical response and high-electroluminescence; they might be used for example in large area display technology.
