Abstract: The absorption and emission spectra of one-dimensional linear aggregates and two-dimensional herringbone aggregates were investigated via Frenkel exciton model. The introduction of the exciton delocalization length bridges a link between spectral lineshape fuctions of molecular aggregates and single molecule. The results show that the spectra of molecular aggregates are closely dependent on the molecular alignment. The red\|shift absorption in linear J aggregates and splitting of J and H bands in herringbone aggregates are analyzed. The simulated absorption and emission spectra are in consistent with experimental results.

Key words: Molecular aggregate, Absorption and emission spectrum, Frenkel exciton, Exciton delocalization length