I. I. Davidenko

Information media based on electron donor oligomers with different structures

Information properties of recording media for photothermoplastic techniques were investigated. The films consisted of oligomer composites based on carbazole containing co-oligomers of linear and radial structures with branching centers on silicon and germanium atoms. It was ascertained that the media based on the radial oligomers possessed high holographic sensitivity because of the high plasticity and its ability to accumulate volume electric charge during the exposure. Examples of practical applications of the investigated recording media are presented.

Reversible holographic recording media based on polymeric composites and their use in energy-saving technologies.

The principle of the photothermoplastic method of hologram recording and the general requirements for photothermoplastic holographic recording media based on photoconductive polymer films are considered. The holographic recording media obtained by the authors based on carbazolyl- and ferrocenyl-containing oligomers doped with respective squarillium or merocyanine dyes are discussed. Some examples of practical application of such media in holographic interferometry are demonstrated.

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.

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 External Electric Field on Diffraction Efficiency of Polarized Holograms in Films of 4-[(2-Nitrophenyl)Diazenyl]Phenyl Methacrylate Copolymer With Octyl Methacrylate

Holograms with a plane wavefront for parallel and orthogonal orientation of polarization of the light beams were obtained in films of the 4-[(2-nitrophenyl)diazenyl]phenyl methacrylate copolymer with octyl methacrylate, and the effect of an external electric field on their diffraction efficiency was investigated. Two effects from the electric field on the diffraction efficiency of the reconstructed holograms were observed: a fast effect leading to decrease of the diffraction efficiency and a slow effect leading to increase of the diffraction efficiency in the reconstructed holograms. The mechanism of formation of the latent holographic image and the effect of the external electric field on it are due not to the photosemiconducting properties of the films but to optical anisotropy in the isomers of the azobenzene groups and the formation of regular surface relief in the films.

Effect of Oligomer Structure on the Diffraction Efficiency of Holographic Recording Media

A study was carried out on the photophysical properties of photothermoplastic holographic recording media based on film composites derived from linear and branched cooligomers. The diffraction efficiency of the recorded holograms was enhanced by using branched oligomers in the holographic recording media.

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.

Photoconducting Characteristics of Films of Poly(Vinyl Butyral)/Hetero-Polyoxometalate Composite

It was found that the photophysical characteristics of film composites based on poly(vinyl butyral) with additions of particles of the hetero-polyoxometalate complex (NH4)5{[Cu(en)2][PMo8V4O40]}·9H2O have an unusual dependence on the duration of illumination with visible light, which is expressed as change in the sign of the photocurrent during long-term illumination. It is suggested that the negative photoconductivity is due to the formation of significant volume charge in the volume of the composite film. It was concluded from analysis of the photovoltaic characteristics that the volume charge is formed by non-equilibrium negative electric charges. A phenomenological model that describes the observed effect is proposed.