M. A. Brusentseva

Electroluminescence of polymer/J-aggregate composites

Efficient electroluminescence was revealed in single-layer light-emitting diodes based on electron-hole conducting polymers containing the nanocrystalline phase of cyanine dyes (J-aggregates). These species exhibit a very narrow emission band with a maximum in the red to infrared spectrum range. The J-aggregates play an active role in the charge carrier transport of the composites.

Bright blue–green electroluminescence from aromatic polyimides

New polyimide type of polymers, aromatic polyimides (APIs) containing sulphur atoms in the backbone, were investigated as electron-hole transporting and light-emitting materials for use in unilayer electroluminescent diodes. The simplicity of synthesis, high thermal stability, organic solvent solubility together with excellent film-forming properties make the APIs potentially of interest for technological applications.

Aromatic Polyimides as Efficient Materials for Organic Electroluminescent Devices

Derivatives of newly synthesized aromatic polyimides containing sulphur atoms in the backbone were studied as electron-hole-transporting and light-emitting materials for use in combination with tris(8-hydroxyquinoline)-aluminium in multilayer organic electroluminescent devices. Efficient bipolar charge transport has been revealed in the polymers. Bright electroluminescence (15 000 cd m -2 at 14V) was observed in the visible range. The possible role of intermolecular donor-acceptor interactions in the mechanism of electroluminescence is discussed.

J-AGGREGATE ELECTROLUMINESCENCE IN DYE DOPED POLYMER LAYERS

The electroluminescence (EL) of a dye nanocrystalline phase was revealed in single layer light-emitting diodes based on polymers doped with cyanine dye molecules. Observation of light emission in the visible range depended on the redox potentials of the dyes used. The 9,10-dithioanthracene-containing polyimides exhibiting efficient electron-hole transport appeared to be appropriate media for the generation of J-aggregate EL.

Electrophosphorescence of aromatic polyimides doped with platinum porphyrins

The mechanism of electroluminescence in polymeric thin-layer devices based on aromatic polyimides and various molecular complexes of Pt porphyrins as heavy-atom-containing luminophores was studied. On the basis of spectral and electron-hole transport properties of aromatic polyimides and Pt porphyrins, as well as the current concepts adopted in polymer photonics, the processes of singlet-singlet and triplet-triplet energy transfer in the examined single-layer systems aromatic PI-Pt porphyrin with a high electrophosphorescence quantum yield exceeding 2% are discussed.

Infrared Electroluminescence in Polymer Composites Based on Organic Nanocrystals

Electroluminescence in polymer nanocomposite structures with electron–hole transport, called J-aggregates, which are based on aromatic polyimides and nanosized crystals of cyanine dyes, is studied. In the near-IR range, the electroluminescence with a narrow emission spectrum (with a maximum at 815 nm) is observed for the first time. It is shown that not only are the organic nanosized crystals of the J-aggregates effective acceptors of the exciton state energy, but they play the role of active electron–hole transport centers in these novel polyfunctional polymer materials.

Molecular nanocrystals in polyaniline-based light-emitting diode structures

It is found that one of the types of molecular organic nanocrystals, the so-called J-aggregates, is able to modify optoelectronic properties of electroactive polymers. It is intrinsic that the polyaniline interpolymeric complex, known as p-type semiconductor, turns into electroluminescent material in the presence of J-aggregates of 3,3-di(gamma-sulfopropyl)-5,5-dichlorotiamonomethincyanine triethylammonium salt. During the studying of new organic light-emitting diode structures, in which the polyaniline/J-aggregates polymeric composite forms both recombination and emitting layers, a polyaniline intrinsic electroluminescence spectrum is obtained. The electroluminescence band completely coincides with the polyaniline photoluminescence spectrum; it has maximum at 400 nm. The electroluminescence mechanism in the studied nanocomposites is discussed.

Synthesis and photophysical properties of polyphenylquinoxalines with thiophene and benzothiophene units in side chains

New bis(α-diketones) with thiophene and benzothiophene moieties were synthesized. A series of new polyphenylquinoxalines containing these moieties in side chains was prepared via polycondensation of these diketones with different aromatic tetramines. The polymers are soluble in a variety of organic solvents, and their solutions form transparent films having a tensile strength of σ = 80–100 MPa and an elongation at break of ɛ = 5–12%. The polymers exhibit fluorescence in solution in trifluoroacetic acid and in films with a maximum at 430–570 and 460–480 nm. The 10% mass loss temperature in air ranges within 440–490°C.

Electroluminescent polymer nanomaterials and structures based on J aggregates

566 An important line in the design of new high-molecular-weight structures with electroluminescent properties is the study of electroactive polymer composites containing a particular type of organic nanosized crystals with semiconductor properties known as J aggregates. Such polymer composites possess a number of advantages as compared to polymer systems doped with low-molecular-weight luminophores or inorganic nanosized particles [1, 2]. We have developed and studied electroluminescent layers doped with nanocrystals of cyanine dye (CD) J aggregates. These particles are efficient luminophores [3] and are used as spectral sensitizers of photographic materials [4].

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.