Excited states of donor and acceptor substituted conjugated oligomers: A perspective from the exciton scattering approach

Quantum-chemical computations allow one to predict a variety of interesting electronic properties of donor and acceptor substituted conjugated molecules. However, the complexity of such systems often limits physical interpretation of the computations and makes them impossible in larger molecules. In this study, the exciton scattering (ES) methodology is extended to analyze the excited-state structure of donor and acceptor substituted conjugated oligomers. The extracted reflection phases, transition charge, and dipole parameters of the modified termini are used to quantify the influence of the substitution on the molecular electronic and optical spectra. In particular, intuitive relationships between the substituent's electron withdrawing or donating ability and the ES parameters are discussed. A good agreement of the absorption spectra between the ES approach and the reference quantum-chemical computations demonstrates that the ES approach is qualified for such conjugated push-pull systems.