Бимолекулярная рекомбинация носителей заряда в чистом и молекулярно допированном разветвленном полифениленвинилене
Abstract—General problems of bimolecular recombination of charge carriers in both pure and molecularly doped branched polyphenylenevinylenes are addressed. Experiments are performed via the nonstationary radiationinduced electricalconductivity method. Transientcurrent curves are numerically calculated in terms of the multipletrapping model. Good agreement between the calculated and experimental curves is attained. In the investigated polymers, the Langevin mechanism of bimolecular recombination is active.
We present a simple model of the bimolecular charge carrier recombination in polar amorphous organic semiconductors in which the dominant part of the energetic disorder is provided by permanent dipoles and show that the recombination rate constant could be much smaller than the corresponding Langevin rate constant. The reason for the strong decrease of the rate constant is the long-range spatial correlation of the random energy landscape in amorphous dipolar materials; without spatial correlation, even strong disorder does not modify the Langevin rate constant. Our study shows that the signi ﬁ cant suppression of the bimolecular recombination could take place in homogeneous amorphous organic semiconductors and does not need large-scale inhomogeneity of the material.
Abstract—General questions about hole transport and bimolecular recombination of charge carriers in molecularly doped polycarbonate with a low dopant concentration (10 wt %) are considered. The experiment is performed via a radiationinduced timeofflight technique with bulk generation of charge carriers. Tran sientcurrent curves are calculated numerically via a multipletrapping model. There is good agreement between the calculated and experimental results on the transientcurrent waveform. Nonequilibrium hole transport is observed in the studied molecularly doped polymer, and the bimolecular recombination is close to the Langevin recombination as described by the multipletrapping model.
We consider the bimolecular charge carrier recombination in amorphous organic semiconductors having a special kind of energetic disorder where energy levels for electrons and holes at a given transport site move in the same direction with the variation of some disorder governing parameter (the parallel disorder). This particular kind of disorder could be found in materials where the dominant part of the energetic disorder is provided by the conformational disorder. Contrary to the recently studied case of electrostatic disorder, the conformational disorder, if spatially correlated, leads to the increase of the recombination rate constant which becomes greater than the corresponding Langevin rate constant. Probably, organic semiconductors with the dominating conformational disorder represent the first class of amorphous organic semiconductors where the recombination rate constant could overcome the Langevin limit.
The dynamics of a two-component Davydov-Scott (DS) soliton with a small mismatch of the initial location or velocity of the high-frequency (HF) component was investigated within the framework of the Zakharov-type system of two coupled equations for the HF and low-frequency (LF) fields. In this system, the HF field is described by the linear Schrödinger equation with the potential generated by the LF component varying in time and space. The LF component in this system is described by the Korteweg-de Vries equation with a term of quadratic influence of the HF field on the LF field. The frequency of the DS soliton`s component oscillation was found analytically using the balance equation. The perturbed DS soliton was shown to be stable. The analytical results were confirmed by numerical simulations.
Radiation conditions are described for various space regions, radiation-induced effects in spacecraft materials and equipment components are considered and information on theoretical, computational, and experimental methods for studying radiation effects are presented. The peculiarities of radiation effects on nanostructures and some problems related to modeling and radiation testing of such structures are considered.