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The photoelectric properties and bulk photovoltaic effect were observed in ferroelectric polyvinylidene fluoride with trifluoroethylene doped with carbon nanotubes and dye on the ground of ruthenium, which are spectral sensitizers to laser beam 532 nm. The efficiency of conversion of light energy into electricity is low and amounts to 0.02% for the composite with carbon nanotubes.

The present study is aimed to elucidate main structural features of polymeric sulfonic acids (the rigidity of main chain, the distance between sulfonic groups on the chain, the hydrophobicity of main chain or side fragments) on the course of 3,4-ethylenedioxythiophene (EDOT) electropolymerization and electronic and chemical structure of the poly(3,4-ethylenedioxythiophene) (PEDOT) films obtained. The films were prepared by electrochemical polymerization in cyclic voltammetry, potentiostatic, and galvanostatic regimes in aqueous solutions of different polyacids in the absence of supporting electrolyte. The effect of the chemical structure of polyacid on the course and rate of PEDOT synthesis was traced by electrochemical and in situ UV-Vis spectroscopic methods. It was shown that the highest rate of EDOT electropolymerization is achieved in the presence of flexible-chain polyacid having hydrophobic fragments (groups) in its structure, followed by hydrophobic rigid-chain polyacids. The lowest rate was observed in the presence of hydrophilic flexible-chain polyacid. The electronic and chemical structure of the PEDOT films obtained was studied by in situ UV-Vis-NIR and Raman spectroelectrochemistry. The films prepared in the presence of rigid-chain polyacids at high anodic potentials demonstrate decreased content of bipolaronic fragments in their structure, while PEDOT complexes with flexible-chain polyacids are very much like conventional polymer prepared in non-aqueous medium. The results are discussed in terms of conformational state (ability to form coils and thus concentrate the monomer) of different polyacids in aqueous solution and hydrophobic interactions between the polyacids and EDOT.

The optical and photoelectric properties of present-day photosensitive polymers are of particular interest due to their prospects for use in various photoelectric applications. Here the absorption edge is studied by the constant photocurrent method which is widely used for studies of inorganic materials. For the objects to be studied, PCDTBT and PTB7 polymers and their mixtures with the PC71BM fullerene derivative are chosen. The spectral dependences of the absorption coefficient for the pure polymers and mixtures are approximated on the assumption of the Gaussian distribution of the density of states in the bands of the components, which provides a means for estimating the electrical band gaps. In addition, such processing of the spectra makes it possible to confirm some important inferences about the states responsible for optical transitions in the low-energy absorption region.

Nanocomposites based on graphene and polyaniline–polyacid complexes with tunable electrical conductivity are elaborated. An influence of graphene oxidation degree on conductivity of the nanocomposites is investigated. The change of optical and electrical properties after graphene introduction into polyaniline–polyacid complexes is explained by the formation of graphene nanostacks of different size and their different distribution in the film bulk. The role of (i) internal interactions between graphene sheets revealed by high-resolution TEM and AFM and (ii) external interactions between graphene and polyaniline or polyacid of different hydrophobicity elucidated by UV–vis, FTIR-spectroscopies and pH-measurements is discussed. In case of uniform distributed graphene sheets having a low oxidation degree, the electrical conductivity of the nanocomposites based on polyaniline complexed with more hydrophilic polyacid increases up to 20 times in respect to initial polyaniline complex.

Electrodeposition of polyaniline (PANI) complexes with a polymeric sulfonic acid of variable molecular weight has been studied with the purpose to explain specific features of aniline electropolymerization in the presence of polyelectrolytes. Poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA) was taken as a model polyelectrolyte due to the ease of varying its molecular weight during polymerization of the monomer. Depending on the polyacid molecular weight, crucial changes in the shape of charge– and potential–time dependences and cyclic voltammograms have been observed during potentiostatic, galvanostatic, and cyclic voltammetry syntheses of PANI, respectively. The results are considered in terms of the influence of molecular weight on proton condensation ability of the polyacid and, therefore, on the degree of aniline protonation and its local concentration in the vicinity of polyacid macromolecule. The PANI films obtained are characterized by cyclic voltammetry and UV–vis and Raman spectroelectrochemistry, and the influence of the polyacid molecular weight on these properties is discussed.

A crystallographic analysis of optical fluorescent images of two-dimensional polygonal structures of J-aggregates of 3,3′-di(γ-sulfopropyl)-5,5′-dichlorothiamonomethinecyanine (MCD) cyanine dye has been performed. In aqueous solutions, MCD forms striplike J-aggregates in the form of extended strips with parallel sides and an oblique or right-angled end. It is found that the acute angle in oblique J-aggregates has a single value close to 45°. The staircase model of molecular packing in oblique J-aggregates is proposed with a slippage angle of 25° expected from the molecular simulation. Within this model the sides of aggregates are formed by the [100] and $$[\bar 110]$$ faces, and the acute angle between them is equal to the experimentally observed angle. Right-angled rectangular J-aggregates are presumably described by the ladder model.

We demonstrate that the solvent-free mechanochemical method, previously used for the synthesis of polyaniline (PANI) protonated with low molecular weight inorganic acids, can be extended to the preparation of conductive, all-polymeric PANI/polyacid molecular composites. Two polymeric sulfonic acids differing in their chain rigidity were selected as PANI protonating agents, namely: poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (PAMPSA, flexible backbone polyacid) and poly(p,p′-(2,2′-disulfonic acid)-diphenylene- tere -phthalamide) ( t -PASA, rigid backbone polyacid). Spectroscopic (UV–vis–NIR, FTIR, EPR), morphological, structural (TEM), electrochemical and spectroelectrochemical properties of the mechanochemically prepared molecular composites were compared with those determined for their analogs synthesized by oxidative polymerization in aqueous solution. The mechanochemically synthesized molecular composites show a characteristic layer-type morphology, distinctly different from that observed for the composites prepared chemically in aqueous solutions. UV–vis–NIR and FTIR spectroscopy clearly indicate better polaron delocalization in the mechanochemically prepared samples. These results are in line with those obtained in ESR, electrochemical and spectroelectrochemical investigations unequivocally showing better charge carrier delocalization in the mechanochemically prepared composites. The measured dc-conductivity of the mechanochemically prepared samples is 24 mS/cm and 31 mS/cm for PANI/PAMPSA and PANI/ t -PASA, respectively.

The effect of cyanine dye additives on the photoelectric, nonlinear optical, and photorefractive properties of polyvinyl carbazole composites based on closed singlewalled carbon nanotubes has been inves� tigated. It has been found that these characteristics are affected by the dye in which the lowest unoccupied molecular orbital (LUMO) lies below the level of the photoexcited nanotube. The addition of this dye to the composite leads to a 14�fold increase in the quantum efficiency of the generation of mobile charge carriers under irradiation by a laser (1064 nm) in the absorption region of the nanotubes. Moreover, the addition of the dye to the composite decreases the thirdorder susceptibility χ (3) , presumably, due to the opposite orien� tations of dipoles of the dye and the nanotube upon adsorption of the dye on the nanotube. The addition of the dye to the composite also provides a twofold increase in the twobeam photorefractive amplification factor of the laser beam with a wavelength of 1064 nm. The obtained values of the twobeam photorefractive ampli� fication factor reach 120 cm -1 .

Photophysical and electrical properties of new synthesized 2,6-polyphenylquinolines (PPQs) containing an oxygen or phenylamine bridging group between quinoline cycles and, as an arylene radical, alkylated derivatives of carbazole or indolo[3,2-b]carbazole are studied. It is shown that the photosensitivity for new PPQs is 104–105 cm2/J and the photogeneration quantum yield of free carriers is as high as 0.15. Photophysical parameters increase with the phenylamine bridging group in place of the oxygen one and when using indolocarbazole instead of carbazole. It is found that a film of polyphenylquinoline containing an oxygen bridging group and an alkylcarbazole fragment in the polymer repeat unit exhibits “white” luminescence. Both electron and hole transport with a mobility of ∼10−6 cm2/(V s) are detected in films of all studied polymers. The conductivity value and type can be controlled by varying the chemical structure of the (oxygen or phenylamine) bridging group between PPQ cycles and by choosing carbazole or indolo[3,2-b]carbazole derivatives as an arylene radical.

Atomic force microscopy (AFM) was used to obtain high-resolution images of nanosized organic J-aggregate molecular crystals of 3,3′-di(gamma-sulfopropyl)-5,5-dichlorotiamonomethinecyanine (TC) and 3,3′-bis(2-sulfopropyl)-5,5′,6,6′-tetrachloro-1,1′-dioctylbenzimidacarbocyanine (C8S3) and precise height measurements of J-aggregates monolayers were conducted. It was found that TC J-aggregates obtained both in the solution bulk and by self-assembly on the mica surface are extended monolayer sheets of high mechanical flexibility. The height of TC is 1.05 ± 0.05 nm, which corresponds to the crystallographic size of a single molecule along the short axis. A model of asymmetric single-layer molecular packing is suggested in which sulfopropyl groups are located on the same side of the layer plane. In the case of C8S3, narrow multilayer ribbonlike structures with heights of 3 to 30 nm were observed. The heights are strictly quantized with a step of 3 nm. A bilayer model of C8S3 molecular packing in J-aggregates is discussed with partially interpenetrating monolayers with hydrophobic sides oriented face to face. A model of structural C8S3 units as “elementary ribbons” with the transverse dimensions of 3 × 4 nm is suggested on the basis of the comparison of AFM data with electron microscopy data from other works.

The model of metallic type or enhanced hopping conductivity with reduced activation energy at the donor–acceptor interface formed by organic dielectrics is suggested. High density of electrons and holes at the interface arises due to the integer charge transfer from donor to acceptor molecules. Significant part of charge carriers can avoid thermal activation and tunneling in course of their transport if the interfacial energy barrier is low enough. The critical value of an interfacial energy barrier, density of free electrons, the values of two-dimensional mobility and conductivity of charge carriers are estimated by numerical modeling and compared with experimental data.

The electron-hole transport in poly(diphenylene phthalide) films has been investigated. The dependence of the drift mobility of charge carriers on the excessive mechanical pressure has been studied using the time-of-flight method. It has been revealed that, with an increase in the thickness of the polymer film, the dispersive transport of charge carries gives way to the quasi-dispersive transport. In thin films in the prethreshold range (i.e., before switching of the samples to the highly conductive state under excessive pressure), the electron mobility increases and exceeds the hole mobility. The experimental results have been discussed in the framework of the model describing the transport through the channels formed by metastable electron-hole pairs.

The photophysical properties of new synthesized indolocarbazoles, i.e., indolo[3,2-b]carbazole and its derivatives, have been comparatively analyzed. It is shown that their photosensitivity (total photosensitivity to (5–8) × 10−2 (lx s)−1, spectral photosensitivity ∼105 cm2 J−1, and free carrier photogeneration quantum yield of 0.1) and transport (effective mobility in 5,11-dioctyl indolo[3,2-b]carbazole is more than 10−5 cm2/(V s)) parameters significantly exceed those of pentacene, which, among molecular media (organic crystals), exhibits the highest carrier photogeneration quantum yields. The high photoluminescence intensity of synthesized indolo[3,2-b]carbazole derivatives shows promise for their applicability in electroluminescent devices.

With the purpose of determining prospects of possible applications of interpolymer complexes of polyaniline (PANI) with poly(amidosulfonic acid)s, we have performed a comparative study of polyaniline films prepared by electrochemical polymerization of aniline in the presence of the polyacids distinguished by different rigidities of the polymer backbone: (1) poly(2-acrylamido-2-methyl-1-propanosulfonic acid) (flexible backbone); (2) poly-p,p′-(2,2′-disulfoacid)-diphenylen-iso-phthalamid (semi-rigid backbone); (3) poly-p,p′-(2,2′-disulfoacid)-diphelylen-tere-phthalamid (rigid backbone); and (4) a copolymer of the latter two acids with monomer feed ratio 1:1 (co-PASA). Spectroelectrochemical studies in the UV–vis–NIR range showed that PANI complexes with rigid-chain polyacids far more effectively modulate absorbance in the Vis–NIR range and can be considered as promising candidates for “smart windows” development. Due to the presence of bulky unmovable polyacid anion, PANI interpolymer complexes (particularly those with the semi-rigid-chain polyacids) possess much wider pH range of electroactivity than common PANI, which is of great importance for biosensor applications. The interpolymer complexes with flexible-chain and semi-rigid-chain polyacids exhibit good optical response to ammonia vapors at conditions of high humidity, which make them promising materials for the development of ammonia optical sensors.

Various polyaniline (PANI) interpolymer complexes with polyacids in the form of molecular solutions were synthesized by chemical oxidative polymerization of aniline in the presence of water-soluble poly-(2-acrylamido-2-methyl-1-propanesulfonic acid) (flexible backbone), poly-p,p′-(2,2′-disulfoacid)-diphenylene-terephthalamide (t-PASA, rigid backbone), and their mixtures in different ratios. The complexes were characterized by UV-Vis-near infrared spectroscopy in solutions; also, the films’ drop-casts from these solutions were investigated by cyclic voltammetry, spectroelectrochemical, direct current (DC) conductivity, and atomic force microscopy (AFM) measurements. It was shown that the nature of polyacid affects the shape of spectra and the dynamics of their changes. The character of spectral changes during the matrix synthesis of PANI in the presence of mixtures of the rigid-chain and flexible-chain matrixes and the study of spectral properties of the obtained PANI solutions demonstrates the existence of the rigid-matrix domination effect in the process of formation of PANI interpolymer complexes. Spectral properties of the obtained PANI complexes with the mixtures of flexible-chain and rigid-chain polyacids of different ratios (3:1, 1:1, 1:3, and 1:6) are very similar to those ones for the complex with rigid-chain t-PASA. At the same time, there is a correlation between the electrical conductivity and morphology of the films of PANI complexes and their composition, the conductivity passing through a minimum for the complexes with the polyacid mixtures (6:1, 3:1, and 1:1).

The hopping mobility of charge carriers (both at the surface and in the bulk) is analyzed theoret� ically in the presence of electron-hole pairs. A physical model is suggested for the metal conductivity over the interface between organic materials, each being an insulator by itself. The conductivity is due to the rather high surface density of geminate pairs formed at the interface. Conditions are established wherein the transi� tions of a significant portion of charge carriers between molecules do not require thermal activation or tun� neling. The surface conductivity and mobility of charge carriers are estimated by numerical simulation.

The electroluminescence and charge carrier transport in an organic light-emitting diode based on a thin polymer film are investigated. The initial kinetics of transient electroluminescence is analyzed theoretically. Both the theoretical and experimental curves are characterized by an anomalous dispersion and universality, which can be considered a consequence of the nonequilibrium field-assisted dispersion of charge carriers. It is demonstrated that the drift mobility of charge carriers should be determined from the time corresponding to the half-height of the steady-state electroluminescence intensity rather than from the delay time of the electroluminescence.

Photoelectric and electrical properties of polyphenylquinolines differing in the structure of donor bridge groups between quinoline moieties have been studied. It is demonstrated that films of the polymers synthesized exhibit a photosensitivity at the level of 105 cm2 J−1 (integrated sensitivity 5 × 10−4 lx−1 · s−1), with a quantum yield of carrier photogeneration of 0.07 and a carrier drift mobility on the order of 10−6 cm2 V−1 s−1. The fact that the electron and hole drift mobilities in polyphenylquinoline with a phenylamine bridge group are balanced makes the polymer promising for development of film-type devices based on the bipolar conductivity of a material (e.g., single-layer light-emitting diode).

Nanostructured polymer materials doped by molecular aggregates and chromophores; the mechanism of electron conductivity in these systems; the effects of a combination of conductivity with optical, photophysical, emissive properties of thin-film polymer systems; and various devices on the basis of these properties and effects and discussed.

The effect of energetic disorder on charge carrier transport in organic materials has been reexamined. A reliable method for mobility calculation and subsequent evaluation of relevant disorder parameters has been discussed. This method is well suited for a direct calculation of the magnitude of dipolar disorder σdip in polar organic materials from the current transients. Calculation of σdip for several transport materials with varying concentration of polar dopants gives concentration dependences that are in reasonable agreement with theoretical predictions. A possible solution of the puzzle concerning the disorder effect on the mobility temperature dependence has been suggested.

Photorefractive materials based on unplasticized polymers that have a high glass transition temperature and the frozen random orientation of chromophores are prepared by layer casting. Under these conditions, only the third-order susceptibility has a nonzero value, by increasing with an increase in the conjugation chain length and reaching considerable values in the case of nano-sized molecules, such as single wall carbon nanotubes. In single wall carbon nanotubes containing poly-N-vinylcarbazole, the photoelectric sensitivity and photorefractive characteristics are measured at 1064 and 1550 nm.

Theoretical analysis of transient electroluminescence in thin organic films controlled by non-equilibrium charge transport is carried out including space-charge effects. Results are compared with experimental data for a 100-nm-thick film of a phenylenevinylene co-polymer. Normalized transients are highly dispersive and universal at the initial time interval, which is considered as a manifestation of the non-equilibrium field-assisted dispersion of holes. Transit time is the half-rise time rather than the delay time.

The correlation between morphology and charge-carrier mobility in the vertical direction in thin films of poly(2-methoxy-5-(2′ethylhexyloxy)-1,4-phenylenevinylene) (MEH-PPV) is investigated by a combination of X-ray reflectivity (XRR), field-emission scanning electron microscopy (FESEM), atomic force microscopy (AFM), fluorescence optical microscopy (FOM), photoluminescence spectroscopy (PL), photoluminescence excitation spectroscopy (PLE), as well as time-of-flight (TOF) and transient electroluminescence (TrEL) techniques. The mobility is about two orders of magnitude greater for drop-cast films than for their spin-cast counterparts. Drop-casting in the presence of a vertical static electric field (E-casting) results in films with an additional increase in mobility of about one order of magnitude. While PL and PLE spectra vary with the method of film preparation, there is no correlation between emission spectra and charge-carrier mobility. Our XRR measurements on spin-cast films indicate layering along the film depth while no such structure is found in drop-cast or E-cast films, whereas FESEM examination indicates that nanodomains within drop-cast films are eliminated in the E-cast case. These observations indicate that carrier transport is influenced by structure on two different length scales. The low mobility observed in spin-cast films is a direct result of a global layered structure with characteristic thickness of ca. 4 nm: in the absence of this layered structure, drop-cast films with inherent nanoscale heterogeneities (ca. 20 nm in size) exhibit much better hole mobility. Elimination of nanodomains via electric-field alignment results in further improved charge mobility.

Heterogeneity relates to the principal features of polyaniline (PAn). For the most part the heterogeneity in PAn belongs to redox type. Our detailed investigation of the vacuum deposited PAn and the study of the luminescence of PAn base (by Shimano and MacDiarmid) reveal the existence of a block structure of PAn molecules formed of quinoid and amine units. There are also direct evidences of existence of the redox heterogeneity in PAn in nano scale (Kelvin scanning microscopy). We have observed by optical and Kelvin the microscopy the formation of various types of the redox heterogeneous structures in microscopic scale in the course of the chemical or electrochemical treatment of the vacuum thermally deposited or electrochemically produced PAn films. Macroscopic scale redox heterogeneity was observed also under chemical oxidation of the vacuum deposited PAn and in the course of PAn matrix synthesis. Hence, multilevel redox heterogeneity from molecular to macroscopic scale takes place in PAn. The fundamental reason for the redox heterogeneity formation is the autocatalytic, non-equilibrium character of the oxidation processes in PAn coupled with non-linear mass transfer processes. Evidently this type of heterogeneity influences markedly the whole range of PAn properties including conductivity.

The hole and electron drift mobility, photoelectric properties as well as influence of temperature, dark current and also relative position of oxidation potentials of the interacting components on photorefractive characteristics of the composites from aromatic polyimide doped with nanocrystalline J-aggregates of a cyanine dye are presented. The nanocrystalline J-aggregates were used as the photosensitizers and also as nonlinear optical chromophores. The experimental electric field dependence of the charge carrier photogeneration efficiency is well fitted by Onsager equation when the quantum yield of the bound thermalized electron-hole pairs φ0=1 and the initial separation of the charges in the pair r0=14.1A. The charge photogeneration time constant determines the response time of the photorefractive grating formation. The polymer composites exhibit gain coefficient Γ=218cm-1 and response time shorter than 20ms at applied electric field 50V/μm and a intensity of each writing beam 30mW/cm2. The net gain coefficient Γ-α=143cm -1.

In this paper we have investigated organic light emitting diodes with such electroluminescent materials as aromatic polyimide, poly∼N-vinylcarbazole (PVK) and dye doped PVK. N-type current–voltage characteristics with negative differential resistance for the thin polymeric and organic films are analyzed. No reasonable explanation has been provided for this phenomenon until now. Here we suggest that a polymer(organic)/metal interface containing various inhomogeneities and metal spikes is responsible for this effect. We detect also the black-body radiation, whose temperature exceeds both the melting point and the sublimation temperature of the metal of the electrode. We suppose that the current density through the spike in any cases is large enough to cause the explosion of the tip of the spike and the detected radiation has the hot plasma origin. (© 2003 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

In bispyrazolopyridine derivatives dispersed into polystyrene, transient currents have been studied using a conventional time-of-flight method. A field dependent electron drift mobility, in the range of 4 × 10 -7 -2 × 10 -5 cm 2 /(Vs) at an electric field of (0.6-7.0) × 10 5 V/cm, has been found. The correlation between chemical structure and measured mobility is found to fit the correlated disorder model reasonably when the charge transport is represented in terms of the one-electron transfer between frontier molecular orbitals. Optimisation of molecule configuration and calculation of the orbital energy and wave-function decay constant have been computed by the semi-empirical methods. The PM3 approach is shown to approximate experimental data more better than the AM1.

The paper demonstrates photorefractive characteristics of the aromatic polyimide (T_g=230\,^\circ\hbox{C}) containing J-aggregates of the thiacarbocyanine dye. The two wavelengths 647\,\hbox{nm} and 514\,\hbox{nm} of Ar-Kr-laser were used. The J-aggregates of the dye are responsible for optical absorption at 647\,\hbox{nm} . At that wavelength the net gain coefficient increases from \Gamma-\alpha=217\,\hbox{cm}^{-1} to 361\,\hbox{cm}^{-1} with growth of external electric field E_0 from 16 to 123\,\hbox{V}/\rmu\hbox{m} . Only samples containing J-aggregates exhibit the PR effect at wavelength 514\,\hbox{nm} at which the laser excites monomeric form of the dye. The estimated at 514\,\hbox{nm} and E_0=16\,\hbox{V}/\rmu\hbox{m} two-beam gain coefficient is near 480\,\hbox{cm}^{-1} and the net gain \Gamma-\alpha is about 118\,\hbox{cm}^{-1} . The high glass temperature of aromatic polyimide should appreciably limit the orientation...

Explicit formula connecting roughness profile of an electrode with the distribution of the electric field at its surface is derived for the case of smooth roughness, when typical height of rough ness element is small in comparison to its size across a surface. An efficient numerical method is suggested for the calculation of the field distribution at the surface of very rough electrode. This gives us a possibility to calculate various injection properties of the electrode for a particular kind of injection rate: integral injection rate, surface distribution of injection peaks etc. It is shown also that rough surface of electrodes generates an additional energy disorder in the bulk of transport layer. This principal result indicates that electrode roughness affects not only carrier injection but carrier transport as well.

Hole and electron transport has been studied by the time-of-flight technique on disubstituted diaryldiacetylene layers prepared by the vacuum deposition method. Basic transport characteristics and their dependence on the electric field, temperature and chemical structure of molecules are determined. The data are fit well into a correlated disorder model. Results of an semiempirical quantum-chemistry calculation (PM3, ZINDO/S) on diaryldiacetylene molecules are in agreement with the experimental data.

Recently it was found that the mobility field dependence in disordered organic materials is closely connected with the spatial decay of the energy correlation function. For example, a dipolar glass produces a correlation function decaying as inverse distance, thus leading to a well-known Poole-Frenkel (PF) field dependence. From this point of view a frequent experimental observation of the PF dependence in nonpolar organic materials cannot be explained. We show that the model of quadrupolar glass which is suitable to describe transport properties of nonpolar materials produces a field dependence that is very close to the PF one if measured in not very wide field range. Dispersive effects bring this dependence even more close to the PF one.

Electron and hole drift mobilities were measured by the time-of-flight technique in films of aromatic polyimides based on 9,10-bis(p-aminophenyl)anthracene or 9,10-bis(phenylthio)anthracene and a series of diimide fragments. The electric field and temperature dependences of the mobilities were detected. In amorphous films of the soluble polyimide the drift mobility was found to reach the value of 10 -4 cm 2 v -1 s -1 at 5.5×10 5 V cm -1 . In the insoluble polyimides films, the mobility was lower by one or two orders of magnitude. This is attributed to the presence of cavities in the films of the insoluble polyimides.

The electroluminescence of J-aggregates was detected in polymer systems doped with cyanine dye molecules. J-aggregate/polymer composites exhibiting intense absorption band with a maximum in the red range were developed on the base of polyimides and a copolymer formed from phenylacetylene and 4-methylcoumarin-4-pentynoate. Efficient electrolumunescence was revealed in these systems. It was found out that J-aggregates play an active role in charge carrier transport in the composite materials.

For the doped polystyrene transport films, it was experimentally found that drift mobility decreased when disordered dipole transport molecules were oriented along the external electric field. The trend of decreasing mobility when dipole moment of molecules increases appears to be observed among derivatives of compounds of a kind.

For doped polymer transport films, it has been experimentally found that electron and hole drift mobilities are decreased when disordered dipole transport molecules are oriented along the external electric field.

Thin homogeneous films exhibiting effective hole transport with drift mobility values up to 10 −4 cm 2 V −1 s −1 are formed in the process of vacuum thermal deposition of monomeric diaryldiacetylenes. Basic transport characteristics and their dependence on the electric field, temperature and chemical composition of the monomers are determined.

Using a dipole trap model we propose an explanation of the experimentally observed drastic decrease of the carrier drift mobility with the increase of average distance between transport sites. We demonstrate that in general case mobility activation energy depends on this distance. In addition we demonstrate that observation of the decreasing dependence of activation energy on average intersite distance must be a very rare event, in full agreement with experimental data. We show that the absolute value of the mobility, calculated using our approach, is in good agreement with the experimental one. We demonstrate that it is natural to expect the approximate independence of the activation enery on the average intersite distance for dopants with high dipole moments. Such correlation was really observed in experiments.

Using a dipole trap model we propose an explanation for the different types of behaviour of the charge carrier mobility dependence on the average intersite distance. We show that the whole variety of mobility behaviours may be described within one framework. We predict that, at least for one system, the mobility ‘prefactor’ at low temperature must be an increasing function of an intersite distance.

The pecularities of charge carriers transport in conjugated polymers are discussed.

Calculations of the electric field effect on the escape rate of charge carriers from dipole traps were carried out by the Monte Carlo method. The results obtained are in good agreement with the experimental data on the temperature and field dependence of the charge carrier mobility in disordered organic matrices. We suggest some possible experimental tests for the verification of the dipole trap model.

A realistic model is presented which describes the influence of an electric field E on charge mobilities μ in polymers. This influence is explained by the decrease of the activation energy of the escape of the charge carriers from dipole traps with increase of E . The relations obtained are in good coincidence with experimental data. The model explains the observation of the Pool-Frenkel-type relation, ln μ∼ E 1 2 , without unreal assumptions about the presence of charged traps in high concentration in the polymer matrix.

This article corrects: Nanostructure-Dependent Vertical Charge Transport in MEH-PPV Films Vol. 17, Issue 15, 2902–2910. Article first published online: 28 AUG 2007

Transient radiation-induced conductivity (TRIC) of some 14 polymers is investigated under pulse (0.8 to 3.6 ms) irradiation by 7.7 MeV protons and 20 MeV α-particles at room temperature. TRIC per unit dose rate tends to decrease appreciably for protons and even more so for α-particles compared to electrons. The effect is especially pronounced (reduction factor 10 to 23) for polymers whose TRIC is due to free electron–hole pairs (PET, PS, PPMI). In polymers with dominating geminate electrons (PE, PTFE, PA etc.) this factor is no more than five. An interpretation is given in the framework of the grossly simplified model of track structure. Bei Zimmertemperatur wird die transiente strahlungsinduzierte Leitfahigkeit (TRIC) von vierzehn Polymeren unter Impulsbestrahlung (0,8 bis 3,6 ms) von 7,7 MeV-Protonen und 20 MeV-α-Teilchen untersucht. Die TRIC pro Einheitsdosisrate scheint sich betrachtlich zu verringern fur Protonen und noch mehr fur α-Teilchen im Vergleich zu Elektronen. Der Effekt ist besonders ausgepragt (Reduzierungsfaktor 10 bis 23) fur Polymere deren TRIC durch freie Elektronen–Lochpaare (PET, PS, PPMI) verursacht wird. In Polymeren mit dominierenden Geminate-Elektronen (PE, PTFE, PA usw.) ist dieser Faktor nicht hoher als funf. Eine Erklarung wird im Rahmen eines stark vereinfachten Modells der Track-Struktur angegeben.

The emeraldine base was deposited on SnO2 glass substrates in vacuum by thermal evaporation in the temperature range 275–325 °C. The as-deposited films differ dramatically from the native polyaniline and are formed by the reduction of oligoanilines with molecular weight about 1500. The cycling acid-base treatment of vacuum thermally deposited films gives rise to formation of polyaniline-like material. The property restoration of sublimed films is apparently determined by the restoration of 3D associates in the film body. Molecular structure defects in vacuum-deposited films are responsible for the lower rates of coloration/decoloration, the lower contribution to imine formation and irreversible injection of anodic charge under the first oxidation/reduction cycle. The lower imine concentration in sublimed polyaniline films results in more coloration/decoloration cycles.

We present results of computer simulations of the charge carrier mobility dependence on the electric field and trap concentration in disordered polar organic materials. Recently an unusual dependence of the charge carrier drift mobility in molecularly doped polymers on the concentration of traps has been reported. This dependence differs from the expected inverse proportionality that should be valid for trap-controlled transport. Using our results we argue that this dependence is caused by the existence of different regimes of charge carrier transport for layers with different trap concentrations, i.e. dispersive transport for small trap concentrations and nondispersive transport for high trap concentrations. Our results also show that the mobility, estimated from the time of intersection of the asymptotes to plateaus and trailing edge of photocurrent transient, is very sensitive to variation of transient shape and, in some case, effectively masquerades real concentration and field dependence of the true mobility. Change of the shape with the change of electric field in trap-containing matrices distorts significantly the field dependence of the mobility, calculated by the intersection procedure, and even transforms the usual Poole-Frenkel dependence to the linear one.© (1999) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The time-of-flight electron mobility measurements were carried out for studying the influence of applied electric field and temperature on the transport of charge carriers in ferroelectric vinylidene fluoride-trifluoroethylene copolymers, doped with ortho-dinitrobenzene. The value of electron mobility (mu) equals 3 by 10-10 m2/(Vs) at E equals 1.4 by 108 V/m and T equals 20 degrees C, and was independent of temperature from 20 degrees C to 110 degrees C.© (1998) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

We present results of the Monte Carlo simulation of charge carrier transport in a simple model of randomly oriented dipoles which orientations are locally correlated and compare our results with those obtained for the previously studied model of totally non-correlated dipoles. Also we have Studied the influence of the anisotropic transfer rate on the mobility field dependence. The major result is that Poole -Frenkel field dependence is a very stable phenomenon - it was observed in simulation results for locally correlated media as well as for non-correlated one. The most significant difference is the shift of Poole-Frenkel region to higher fields in the lattice with micro-ferroelectric local ordering. We also study anisotropic charge carrier mobility in the globally sterically ordered dipolar lattice. At last, we made comparison of the simulation results with the analytical solution of 1D model.

We present results of the Monte Carlo simulation of charge carrier transport in a simple model of randomly oriented and orientationally noncorrelated dipoles and compare our results with those obtained for standard Gaussian disorder model. The most significant difference is a shift of the Poole-Frenkel region of the mobility field dependence to lower fields and widening of this region. We have found that in some particular cases the mean carrier velocity is a decreasing function of the electric field.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.