Electron correlation effects on exciton dissociation in the presence of an electric field in polyacetylene

• The dynamics of exciton dissociation in conjugated polymers are investigated.
• Both the effects of electron-lattice and electron-electron interactions are considered.
• The different dynamic dissociation behaviors of SE and TE are emphasized.
• The critical dissociation field for TE is 3 times higher than that of the SE.
• The dissociation behaviors are analyzed by calculating the total energy difference.

Based on the Su–Schrieffer–Heeger and Pariser–Parr–Pople (SSH + PPP) model and the multiconfigurational time-dependent Hartree-Fock formalism, the dynamics of exciton dissociation in conjugated polymers systems has been simulated using a nonadiabatic molecular dynamics method. Within this approach, the appropriate spin symmetry of the electronic wavefunction is taken into account, which allows us to distinguish between singlet and triplet excited states. The different dynamic dissociation behaviors in the presence of an electric field of singlet excitons (SE) and triplet excitons (TE) due to electron correlation are emphasized. Using numerical simulations, it is found that the dissociation of TE under an applied electric field is more difficult than in the case for SE. The critical dissociation electric field strength for TE is about 3 times higher than that of SE. When the conjugated length of a polymer chain is short, SE and TE can each remain as one entity even under high electric field strengths owing to the confinement effect of the chain ends. In addition, the dependence of exciton dissociation on the Coulomb interaction strength, shielding factor and the conjugated length is discussed.

Figure optionsDownload as PowerPoint slide