J-Aggregates Conjugated Polymers

The first observation of J-aggregates of conjugated polymers in solution is reported. Concentrated solutions 1-8.8 mM of conjugated polyquinolines 1a and 1b exhibited narrow, intense, and red shifted absorption bands, smaller Stokes shifts, and shortened fluorescence lifetimes, compared to isolated chains in dilute solution, which are characteristic of J-aggregation. In the solid state 1b formed highly luminescent J-aggregates whereas la formed excimers, reflecting the greater intermolecular distance in 1b. The excitonic delocalization size of the J-aggregates was estimated to be 15-24. These results provide new insights on the role of intermolecular interactions on the luminescence of conjugated polymers and have implications for the design of more efficient electroluminescent polymers, organic lasing materials, and cubic nonlinear optical materials.