Exciton formation with interchain couplings in organic polymers

Based on the framework of the tight binding approach and the nonadiabatic dynamics, the formation of an exciton in inter-coupled polymer chains is studied. Both a localized exciton in one single chain and a spread exciton between chains are obtained. It is found that an excited electron-hole pair is more inclined to evolve into a localized exciton, and the long range Coulomb e–e interaction is favorable to the exciton formation. By calculating the formation time of an exciton, we show that the optical response time is faster in a dilute solution than that in a solid film of polymer molecules.