Eugene I. Mal'tsev

Near-infrared electroluminescence in polymer composites based on organic nanocrystals

IR electroluminescence was revealed in single-layer light-emitting diodes based on a type of electroactive polymer nanocomposites-electron-hole conducting aromatic polyimide and organic nanocrystalline particles of cyanine molecules, known as J-aggregates. These materials exhibit a very narrow emission band with a maximum at 815 nm. Dramatic increase of charge-carrier mobility was observed for these layers containing the J-aggregate nanocrystalline phase.

Nanostructured polymer materials and polymer-based devices

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.

Charge carrier transport in aromatic polyimides and polyimide/J-aggregate composites

In aromatic polyimides based on 9,10- bis(aminophenyl)anthracene or 9,10- bis(phenylthio)anthracene, charge carrier transport has been studied by conventional time-of-flight techniques. The electric field and temperature dependencies of both hole and electron drift mobility were observed. In amorphous film of the soluble polyimide, the drift mobility was found to reach the value of 10-4cm2V-1s-1. In film of the insoluble polyimide containing a crystalline phase, the mobility was lower by one or two orders of magnitude. The result is attributed to the presence of cavities in the crystalline film. The applicability of known theoretical models describing the temperature and electric field dependencies of mobility is discussed. It was found out that J-aggregates, formed in the soluble polyimides doped with cyanine dye molecules, play an active role in charge carrier transport in the electroluminescence composites.

Electroluminescence of polymer nanocomposites

Abstract 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.

J-aggregate electroluminescence in polymer matrices

Cyanine dye electroluminescence was observed in single layer light-emitting diodes based on electron-hole conducting polymers. The appearance of light emission in the visible range depended on the reduction/oxidation potentials of the dyes used. In polymer systems, the electroluminescence of cyanine dye J-aggregate nanocrystalline phase was detected for the first time. 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 coformed from phenylacetylene and 4-methylcoumarin-4-pentynoate doped with the dye luminophores. Efficient electrolumunescence was revealed in these systems. It was demonstrated that J- aggregates play an active role in charge carrier transport in the composite materials. In particular, anthracene-containing polyimides exhibiting electron-hole transport appeared to be appropriate media for the generation of J-aggregate electroluminescence.

A study of hole mobility in diaryldiacetylenes

Abstract 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.

Electroluminescent nanocomposites based on molecular crystals for polymer optoelectronics. Part 1

Experimental data on electroluminescence of new light emitting materials, semiconducting organic polymers doped with nanosized J-aggregates of cyanine dyes, are described. OLED structures are considered. New light-emitting diode structures are developed. Polyaniline electroluminescence band is observed. High-resolution atomic force microscopy (AFM) is used to study J-aggregate structures. The AFM procedure is improved to increase accuracy in determination of J-aggregate dimensions. Certain supramolecular species are long ribbons with high flexibility.

ELECTROLUMINESCENCE OF POLY(HYDROXYAMINO ESTERS) : ALUMINUM COMPLEXES

Abstract We demonstrate that the synthesis of polymer complexes (PHAE-A1) occurs between poly(hydroxyamino esters) (PHAEs) and aluminum by using the conventional vacuum deposition method in the process of thin metal layer formation on the surface of the polymer. These complexes exhibit electroluminescence similar in spectral characteristics to the well-known low-molecular tris(8-quinolinolato) aluminum complex (Alq 3 ). Spectral and electrical data for the polymer light-emitting diodes A1/PHAE-A1/PHAE/PANI with PHAEs of various chemical structure are reported.

Photochemical recording of an image with nonlinear optical properties in polymer layers

The resistless process of the photochemical formation of nonlinear optical pattern in the polymer layer was elaborated. The illumination of the polymer donor-acceptor layers consisting of poly(hydroxyaminoester) as a donor and tetrabromomethane as an acceptor provides second harmonic generation (SHG) due to the photochemical formation of the Michlers hydrol blue like fragment (MHB+). The square root of the SH intensity, I0.5, linearly increases with the increase of exposure dose in region H <EQ 120 mJ cm-2. SHG is absent on unexposed areas of the same layer. SHG arises due to transformation of the geometry of MHB+ cation from centrosymmetric to noncentrosymmetric because of bond-length alternation under influence of Br counteranion.

Electroluminescence and electron–hole mobility of 6,12-di(thien-2-il)indolo[3,2-b]carbazoles

Novel compounds—substituted indolo[3,2-b]carbazoles (SIC)—which demonstrate semiconducting properties are synthesized. Electroluminescence (EL) is studied in multilayer diode structures based on SIC. The values of hole (6.38 × 10–5 cm2/(V s)) and electron mobilities (1.31 × 10–5 cm2/(V s)) of these electroactive materials are measured. It is estimated that heteroaromatic nuclei are the electron transport centers of SIC molecules.