Excitons in two coupled conjugated polymer chains

We have studied the exciton states in two coupled conjugated polymer chains which are modelled individually by the Su-Schrieffer-Heeger Hamiltonian and coupled by an interchain electron-transfer term. Both the intra- and interchain long-range Coulomb interactions are taken into account. The properties of the lowest symmetric and anti-symmetric exciton states are extensively discussed for both the parallel and anti-parallel ordering between these two chains. It is found that, for these two kinds of ordering, the features of excitons are quite different. Possible implications for the experiment of luminescent polymers are also addressed.