Spatial extent of the singlet and triplet excitons in cyano-substituted oligo(phenylene vinylene)s

The singlet and triplet excited states in cyano-substituted phenylene vinylene oligomers are characterized by means of configuration interaction calculations. We first evaluate the vertical singlet-singlet. S0–S1, singlet-triplet. S0–T1, and triplet-triplet T1-Tn, excitation energies in oligomers ranging in size from two to five phenylene rings. We then describe the lattice distortions taking place in the lowest excited states. Finally, we estimate the spatial extent of the S1, T1. and T1 excitons on the basis of a simple analysis of their wavefunctions. In each case, the results are compared to those obtained for the corresponding unsubstituted oligo(phenylene vinylene)s.