title: Forbidden singlet exciton transitions induced by localization in polymer light-emitting diodes in a strong electric field.
abstract: Through combining the electron transition process and dipole moment evolution as well as electron-phonon coupling, molecular dynamics calculations show that the radiative decay of singlet excitons in a conjugated polymer, such as a polymer light-emitting diode (PLED), is largely determined by the evolution of the dipole moment. Without an electric field, the decay life of a singlet exciton is about 1 ns. Once an electric field is applied and exceeds a critical value, with electron-phonon coupling, the original lattice structure evolves into two new localized lattice distortions, consistent with the experimental results. Owing to the new lattice structure and self-trapping, the dipole moment rapidly decreases to zero within 5 fs, eliminating the radiative decay of the singlet exciton.
authors.affiliation: Department of Physics, Zhejiang Normal University, Jinhua, Zhejiang, China.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Sun
authors.forename: Yuan-Ping
authors.initials: YP
authors.lastname: Xu
authors.forename: Sheng
authors.initials: S
authors.lastname: Li
authors.forename: Thomas F
authors.initials: TF
authors.lastname: George