Laser photolysis of polymer EDA complexes including 4,4′-diaminodiphenylmethane derivatives

Transient optical absorption spectra were obtained and photochemical transformations of aromatic amine derivatives (Am) used as electron donors in polymer EDA complexes were studied. It was shown that successive electron — proton — electron processes in (Am.CBr₄) complexes are strongly influenced by whether the Am is monomer or a molecular fragment chemically incorporated into a macromolecular chain.     

Infrared electroluminescence of organic nanocrystals in polymer composites

Electroluminescent polymeric nanocomposite structures that are based on aromatic polyimides and cyanine dye nanosized crystals known as J aggregates and emit light in the IR region were prepared. For the first time, doped polymer systems were found to display IR luminescence whose spectrum had the form of a very narrow band that peaked at 1100 nm. Nanosized J-aggregate crystals in these new polymer materials act not only as effective acceptors of energy of excitonic states but also as active electron-hole transport sites.     

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.     

Radiation-Chemical Degradation of Azo Dye Solutions

The radiation-chemical discoloration of evacuated alcoholic solutions of the azo dye 1-(2-pyridylazo)-2-naphthol was studied using a pulse radiolysis technique. The spectral characteristics of radicals were determined, and the radiation-chemical yields of their formation and dye decomposition were measured. The degradation of the azo dye Acid Yellow 99 under irradiation with -quanta and vacuum UV radiation was compared. The radical mechanism of azo dye degradation in aqueous and alcoholic solutions under exposure to high-energy particles was confirmed.     

Electronic processes at the interfaces between photoactive layers and TiO<Subscript> <Emphasis Type="Italic">x</Emphasis> </Subscript> buffer layers in organic solar cells

The effect a layer of TiO_x located between a photoactive layer and a metallic Al electrode has on the photovoltaic properties of an organic solar cell based on P3HT:PC₇₀BM polymer is studied. The optimum thickness of the TiO_x layer at which the efficiency of the solar cells is highest and the TiO_x layer ensures the transfer of electrons from the photoactive polymer layer to the electrode while blocking vacancies is found to be 10 nm. The effect oxygen has on electronic processes during the operation of the photovoltaic cell is discussed.     

The influence of polyacid nature on poly(3,4-ethylenedioxythiophene) electrosynthesis and its spectroelectrochemical properties

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 conduction switching effect in thin polymer layers

The effect of pressure-induced and field-induced conduction switching in thin polymer layers was experimentally studied. Conduction switching was observed in thin layers of poly(diphenylene phthalide), polyvinylcarbazole, some aromatic polyimides, and methoxypoly(phenylene-vinylene). It was found that conduction switching depends in a critical manner on the formation mode of the metal/polymer contact.