Impurity effects and temperature influence on the exciton dissociation dynamics in conjugated polymers

Energetics of exciton binding and dissociation in polythiophenes: a tight binding approach

A tight-binding exciton model that describes the continuum from the bound exciton to the free hole and electron polarons in conjugated polymer chains is introduced and applied to polythiophenes.

Organic Optoelectronic Materials: Mechanisms and Applications

Organic (opto)electronic materials have received considerable attention due to their applications in thin-film-transistors, light-emitting diodes, solar cells, sensors, photorefractive devices, and many others. The technological promises include low cost of these materials and the possibility of their room-temperature deposition from solution on large-area and/or flexible substrates. The article reviews the current understanding of the physical mechanisms that determine the (opto)electronic properties of high-performance organic materials. The focus of the review is on photoinduced processes and on electronic properties important for optoelectronic applications relying on charge carrier photogeneration. Additionally, it highlights the capabilities of various experimental techniques for characterization of these materials, summarizes top-of-the-line device performance, and outlines recent trends in the further development of the field. The properties of materials based both on small molecules and on conjugated polymers are considered, and their applications in organic solar cells, photodetectors, and photorefractive devices are discussed.

Impact of the electron–phonon coupling symmetry on the polaron stability and mobility in organic molecular semiconductors

Schematic representation of a pentacene stack with two inter-molecular degrees of freedom.

Concentration effects on intrachain polaron recombination in conjugated polymers

The influence of different charge carrier concentrations on the recombination dynamics between oppositely charged polarons is numerically investigated using a modified version of the Su–Schrieffer–Heeger (SSH) model that includes an external electric field and electron–electron interactions.

Polaron stability in molecular semiconductors: theoretical insight into the impact of the temperature, electric field and the system dimensionality

A semi-empirical Holstein–Peierls model is used to study the temperature effects on the polaron stability in organic semiconductors at a molecular scale.

Critical temperature and products of intrachain polaron recombination in conjugated polymers

The intrachain recombination dynamics between oppositely charged polarons is theoretically investigated through the use of a version of the Su–Schrieffer–Heeger (SSH) model modified to include an external electric field, an extended Hubbard model, Coulomb interactions, and temperature effects in the framework of a nonadiabatic evolution method.

Impurity effects on polaron-exciton formation in conjugated polymers

Combining the one-dimensional tight-binding Su-Schrieffer-Heeger model and the extended Hubbard model, the collision of two oppositely charged polarons is investigated under the influence of impurity effects using a non-adiabatic evolution method. Results show that electron-electron interactions have direct influence on the charge distribution coupled to the polaron-exciton lattice defect. Additionally, the presence of an impurity in the collisional process reduces the critical electric field for the polaron-exciton formation. In the small electric field regime, the impurity effects open three channels and are of fundamental importance to favor the polaron-exciton creation. The results indicate that the scattering between polarons in the presence of impurities can throw a new light on the description of electroluminescence in conjugated polymer systems.