Aggregation of a network of conjugated polymer chains: symmetry of the excitonic states and spectral features

Abstract

In this paper, we have theoretically studied the nature of symmetry of the interchain excitonic states for a conjugated polymer aggregate system consisting of N equivalent polymer chains. This approach is applied to show that for any such N-mer aggregate, the 0–0 emission peak is absent at low temperature. The system is studied beyond the nearest-neighbour approximation considering both the electronic and vibrational degrees of freedom. For example, for equivalent tetramer aggregates with square planar (2D) and tetrahedral (3D) structures, the permutation symmetry approach is an appropriate general recipe to classify the symmetry of the eigenstates of both the tetramer systems. The absorption and emission spectra for different classes of aggregates, over a wide range of temperatures, are explained in terms of the symmetry properties of the coupled excitonic states.