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Exciton–vibrational coupling in pinwheel aggregates of π-conjugated molecules

1999; Elsevier BV; Volume: 314; Issue: 5-6 Linguagem: Inglês

10.1016/s0009-2614(99)01078-7

1873-4448

Frank C. Spano, S. Siddiqui,

Luminescence and Fluorescent Materials

Absorption spectra of para-distyrylbenzene (DSB) aggregates are calculated based on a Hamiltonian which includes excitonic coupling between molecules, each containing a single electronic transition coupled to an intramolecular vibration (with frequency ω0 and Huang–Rhys factor λ2). Aggregates are based on the four-molecule pinwheel unit which maximizes the favorable edge–face interactions. Pinwheel aggregates of DSB lie within the intermediate coupling regime, J≈λ2ℏω0, where the excitonic bandwidth J is of the order of the nuclear relaxation energy. A square lattice of pinwheel units lies primarily within the strong coupling regime J≫λ2ℏω0. Theoretical spectra compare favorably with experiment.