Z. An

Dynamical study on polaron formation in a metal/polymer/metal structure

By considering a metal/polymer/metal structure within a tight-binding one-dimensional model, we have investigated the polaron formation in the presence of an electric field. When a sufficient voltage bias is applied to one of the metal electrodes, an electron is injected into the polymer chain, and then a self-trapped polaron is formed at a few hundreds of femtoseconds while it moves slowly under a weak electric field (not larger than

Recombination of polaron and exciton in conjugated polymers

1.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m}).

Interchain coupling effects on dynamics of photoexcitations in conjugated polymers

At an electric field between

Effects of e-e interactions on the dynamics of polarons in conjugated polymers

1.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m}

Dynamics of exciton transfer in coupled polymer chains.

and

Correlation effects on the dynamics of bipolarons in nondegenerate conjugated polymers

8.0\ifmmode\times\else\texttimes\fi{}{10}^{4}\mathrm{V}/\mathrm{c}\mathrm{m},

Spin-flip processes of polarons by magnetic impurities in conjugated polymers

the polaron is still formed, since the injected electron is bounded between the interface barriers for quite a long time. It is shown that the electric field applied at the polymer chain reduces effectively the potential barrier in the metal/polymer interface.

Dynamics of polaron formation in a polymer/metal structure

Both polarons and excitons, which are composite particles with internal lattice structure, play an important role in the transport and light-emitting properties of conjugated polymers for the use in, e.g., polymer based light-emitting diodes (LEDs). The scattering and recombination processes between a triplet exciton and a polaron are investigated using a nonadiabatic evolution method based on an extended Su-Schrieffer-Heeger model including interchain interactions. The results show that an excited polaron state can be formed, besides a triplet exciton is converted into a singlet exciton by the polaron. Moreover, the yields of both the singlet exciton and the excited polaron states increase with increasing interchain coupling strength. The excited polaron is luminescent due to radiative decay as is the singlet exciton. Therefore, our results indicate that the quantum efficiency of polymer LEDs could be enhanced by polaron-exciton recombination.

Dynamic dissociation of trions in conjugated polymers

Within an extended Su-Schrieffer-Heeger model including interchain interactions and the extended Hubbard model, the dynamical relaxation of photoexcitations in two coupled conjugated polymer chains is investigated by using a nonadiabatic evolution method. Initially, one of the two chains is photoexcited and the other chain is in the dimerized ground state. Due to the interchain interactions, the electron and/or the hole can be transferred from one chain to the other chain. For weak interchain coupling, the dynamical evolution of the lattice on the photoexcited chain is similar to that found in an isolate single chain case. With interchain interactions increasing, the amplitude of the distortions on the photoexcited chain decreases, and simultaneously, that on the other chain gradually increases. Until stronger interchain coupling, the deformations of the two chains have almost the same amplitude. Besides intrachain polaron-excitons and intrachain oppositely charged polaron pairs as found in single chain case, interchain polaron-excitons and interchain separated charged polaron pairs are obtained. The results show that the yield of interchain products increases and that of intrachain products decreases with interchain coupling increasing. Totally, the yield of charged polarons (including intrachain oppositely charged polaron pairs and interchain oppositely charged polaron pairs) is about 25%, in good agreement with results from experiments.

Correlation effects on the scattering of soliton pairs in conjugated polymers

Combining the one-dimensional tight-binding Su-Schrieffer-Heeger (SSH) model and the extended Hubbard model (EHM), we investigate the effect of electron-electron interactions on the dynamics of a charged polaron in a conjugated polymer chain, by using a nonadiabatic dynamical method. Both the localization and the velocity of the polaron will vary with the on-site Coulomb interactions U and the nearest-neighbor interactions V. It is found that the local extremum of the stationary velocity of the polaron occurs at U≈2 V (U,V>0). Additionally, the relation between the velocity and the lattice structure of the polaron is shown qualitatively.