E. V. Mokrinskaya

Croconium dye as a sensitizer of photothermoplastic holographic media for the near-IR region

This paper discusses the spectral and photoconductive properties of films based on a co-oligomer of glycidylcarbazole with additives of croconium dye in comparison with similar films with squarylium, merocyanine, and cationic polymethine dyes. It is concluded that croconium dye, like merocyanine dye, belongs to the electron-nonsymmetric organic dyes. The possibility of using croconines as sensitizers of photothermoplastic holographic recording media for the near-IR region is demonstrated for the first time. The lower holographic sensitivity of recording media with croconium dye by comparison with squarylium and merocyanine dyes is associated with the presence of deep traps for charge carriers, which are formed by the molecules of an intraionic dye and are liberated when heated in the process of development of the holograms.

Sensitization of Photosemiconducting Properties of Holographic Recording Media Based on Glycidylcarbazole Cooligomers by Organic Dyes

Photophysical and information properties of the holographic recording media (HRM) based on films of ferrocenyl-containing siloxane oligomer, glycidylcarbazole-butylglycidylic ether cooligomer, ferrocenemethylated oligoglycidylcarbazole, and cooligomer of o-carboxybenzoilferrocene glycidylic ether doped with squarilic dye and(or) with merocyanine dye based on ferrocene and tetranitrofluorene are investigated. It is found that the holographic sensitivity is absent for the media based on ferrocenyl-containing siloxane oligomer, and that the holographic sensitivity is present for the films based on glycidylcarbazole. It has been found that the holographic sensitivity and the photoconductivity of the media based on glycidylcarbazole cooligomers increases with the ferrocene content. This effect has been explained by the influence of iron ions on the rate of singlet–triplet conversion in photogenerated pairs of charges.

Photoconductivity of Polymeric Composites Doped with Porous Silicon Nanoparticles and Additions of Ionic Polymethine Dyes of Different Types

Features of the electrical conductivity and the photoconductivity of polyvinylbutyral films containing silicon nanoparticles and similar films doped with cationic and anionic polymethine dyes are studied. Sensitization of the photoelectric effect by dyes with various ionicities in films is explained by the possible photogeneration of holes and electrons from dye molecules and the intrinsic bipolar conductivity of silicon nanoparticles. It is assumed that the electronic conductivity in silicon nanoparticles is higher as compared with that in nanoparticles with p-type conductivity.

EFFECT OF THE STRUCTURE AND CONTENT OF CARBAZOLYL-CONTAINING CO-OLIGOMERS ON THE DIFFRACTION EFFICIENCY OF HOLOGRAPHIC RECORDING MEDIA

We have established that as the content of glycidyl carbazolyl fragments increases in their copolymers with α-naphthyl glycidyl ether, the photoconductivity of the films increases but the diffraction efficiency of the holograms decreases. Media based on bromine-containing co-oligomers are more holographically sensitive due to the high surface discharge rate for the films during exposure and formation of a latent electrostatic image.

Donor Oligomer Based Film Heterostructures Doped with Squarilium Organic Dye and their Photoelectric Properties

The new heterostructures comprising a squarylium dye (SQ) film deposited onto a oligo-N-epoxypropylcarbazole (OGC) film have been created, and their photoconducting, photodielectric, and photovoltaic properties have been studied. The OGC/SQ heterostructures exhibit the photodiode properties. It is concluded that the p–n junction in these heterostructures is ensured by the hole character of conductivity in the oligomer and the bipolar conductivity of the deposited dye film.

PHOTOVOLTAIC CHARACTERISTICS OF FILM COMPOSITES BASED ON GLYCIDYLCARBAZOLE COOLIGOMER WITH SYMMETRICAL CATIONIC POLYMETHINE DYES

It was found that film composites based on carbazolyl-containing cooligomer with additions of cationic polymethine dyes exhibit photovoltaic characteristics in the absorption region of the dyes. If the length of the polymethine chain is reduced the value of the photovoltaic response is increased as a result of decrease in the energy of the highest occupied orbital of the dye molecule. In samples of the composite films with free surface area the photovoltaic effect is determined by diffusion of the more mobile positive carriers (the Dember effect) and by their recombination time.

Effect of Chromophore Structure of Azo Dyes on Their Diffraction Efficiency in Polarization Holograms of Recording Media

Recording media for polarization holography derived from styrene copolymer films with octyl methacrylate and azobenzene and azonaphthol dyes have been prepared and their informational properties have been studied. We are the first to show that when the orientation of the recording beams changes from parallel to orthogonal, the diffraction efficiency of the holograms increases when using azobenzene and decreases when using azonaphthol. The observed effect of the dependence of the diffraction efficiency on the structure of the chromophores is attributed to the breakdown of symmetry of the chromophore upon going from azobenzene to azonaphthol dye.

Effect of the Dipole Moment of Azo Chromophores on the Information Characteristics of Polymeric Recording Media for Polarization Holography

Recording media for polarization holography have been created using copolymers of azobenzene monomers and octyl methacrylate, and the electrophysical and information properties of these materials have been studied. The increase in the diffraction efficiency of holograms in an external electric field has been found to be faster in copolymers with an azo chromophore possessing a larger dipole moment.

Effect of the Structure of Branched Carbazolyl Oligomers on the Photoconductivity of Film Composites Based on Them

The photoconductivity of film composites based on branched carbazolyl-containing oligomers with the branching center at a silicon atom was investigated. It was found that the photocurrent increases and the photoresponse time in the film composites decreases in the transition to oligomers with greater branching. It is suggested that the increase in photoconductivity is determined by increase in the effective mobility of the holes.

Sensitization of Photoconductivity in Polymeric Compositions with Fe2O3 and CdS Nanoparticles by an Organic Compound with Intramolecular Charge Transfer

The electric conductivity and photoconductivity of films based on polyvinylbutyral and containing Fe2O3 and CdS nanoparticles and an organic compound with intramolecular charge transfer as photoconductivity sensitizer in the visible and near infrared regions were investigated. In the absorption region of the sensitizer the activation energy of the photocurrent is somewhat greater than 0.1 eV and is close to the activation energy of the electric conductivity current.