Effect of electron-electron interaction on scattering process of oppositely charged polarons in conjugated polymers

Abstract

By using one-dimensional tight-binding Su-Schrieffer-Heeger model modified to include electron-electric field interaction and electron-electron interaction, we simulate the scattering process of oppositely charged polarons with spin parallel and antiparallel, respectively. It is found that at weak field, the electron-electron interaction is dominant. Under the effect of strong Coulomb attraction, the polarons with spin antiparallel could not be separated after collision, and ultimately recombine into the singlet exciton. While in case of spin parallel, the strong Coulomb repulsion makes no collision occur unless strengthening the electric field. At moderate field, the electron-electron interaction could facilitate the recombination of polarons into triplet exciton rather than singlet. It is obtained that there exists competition between electron-electric field interaction and electron-electron interaction, a suitable strength of which could promote the formation of exciton in conjugated polymers.