title: Singlet-singlet exciton recombination: theoretical insight into the influence of high density regime of excitons in conjugated polymers.
abstract: Using a modified version of the Su-Schrieffer-Heeger (SSH) model combined with the extended Hubbard model (EHB), the recombination between a singlet exciton pair is investigated under the influence of an external electric field, electron-electron interactions, and temperature effects in the scope of a nonadiabatic evolution method. The excitons are positioned very close to each other in a way to mimic a high-density region in monomolecular conjugated polymer systems. Results show that there are mainly three possible channels resulting from singlet-singlet exciton recombination: (1) forming an excited negative polaron and an excited positive bipolaron, (2) forming two free and excited oppositely charged polarons, and (3) forming a biexciton. These results suggest that the recombination processes critically depends on the condition imposed to the system. The description of this dependence, as carried out in the present work, may provide guidance to improve the generation of free charge carriers in organic optoelectronic devices.
authors.affiliation: Institute of Physics, Universidade de Brasília , 70.919-970 Brasilia, Brazil.
authors.forename: Luiz Antonio
authors.initials: LA
authors.lastname: Ribeiro Junior
authors.forename: Wiliam Ferreira
authors.initials: WF
authors.lastname: da Cunha
authors.forename: Geraldo Magela
authors.initials: GM
authors.lastname: E Silva