Polycarbazole (PCZ) thin films have been electrochemically synthesized on SnO2 coated glass substrates. The electrolyte used was the anhydric LiClO4. It is shown that, after optimization of the potential scanning domain, PCZ films are systematically obtained. The physical and morphological properties of films are described. The films obtained with LiClO4 as electrolyte are homogeneous and their coverage efficiency on the SnO2 underlayer is very high. Films are exempt of pinholes, cracks and other morphological defaults as shown by scanning electron microscopy. Cyclic voltammograms are reversible, attesting the high quality of the structural properties of the films. Moreover these films are photoluminescent. After deposition of an aluminum upper layer, the structures SnO2/PCZ/Al behave like diodes with a forward polarization when the SnO2 electrode is positively biased. Also these structures exhibit electroluminescent properties.

Transparent conductive oxide (SnO2)/organic layers/aluminum thin film sandwich structures have been obtained by vacuum evaporation. The organic component was either a thin carbazole film or a bilayer. In that case, the carbazole film was deposited on a thin insulating polymer film. The polymer used was the poly(tetrabromo-p-phenylenediselenide) (PBrPDSe). Photoluminescence measurements have shown that the carbazole thin films emit blue light. The I–V measurements have shown that the structures exhibit diode characteristics. The forward direction is obtained when the TCO is positively biased. However, the reproducibility of the results obtained with a single carbazole layer is poor. It appears that the stability of the sample is improved when a thin PBrPDSe film (50 nm) is introduced between the carbazole and the SnO2. The polymer film avoids short circuit effect. In that case, the turn-on voltage of the diode is about 3 V, when the thickness of the carbazole film is around 250 nm and the electroluminescence appears at a voltage of about 4 V.

We have performed semi-empirical calculations on a Eu(III)-imidazole complex. We use a Scaled Quantum Mechanical Force field approach from the MOPAC software. We obtain molecular force constants used in the normal mode calculation to modelize experimental Raman frequencies. Furthermore, we discuss the structure and the electronic properties of this complex by means of spectroscopic techniques such as photoluminescence and X-Ray Absorption Near-edge Spectroscopy (XANES).

We present results of calculation of the electronic structure of localized charged excitations induced on the PPV backbone by p-type doping. Dynamical calculations are performed on the basis of model compounds or oligomers. The model compounds approach has allowed to calculate the geometrical distortions of polaronic and bipolaronic segments. The structures obtained are discussed as compared to those presented in other works for n-doped PPV. Results that we present would indicate the absence of electron-hole symmetry in this polymer.

In this work, photoconverted PPV film is characterized by means of optical absorption, photoluminescence, infrared absorption (IR), X-ray diffraction and electrochemical doping. The photoconverted PPV has optical properties close to standard PPV, and electrochemical ones close to thermoconverted PPV at 180 degrees C.

Sintered samples of beta-aluminogallates, Na1+x(Al0.5Ga0.5)(11) O17 + x/2, have been synthesized and studied by high-frequency conductivity and dielectric spectroscopy in the broad frequency range 10(3) to 10(10) Hz. The dielectric measurements have been performed as a function of temperature (290 to 420 K), porosity (18 to 50%) and sodium content y=1+x (1<y<1.5). For frequencies below 10(7) Hz, the complex resistivity plots have made it possible to determine the bulk de-conductivity of beta-aluminogallates with respect to the sodium content by taking account of grain boundaries and porosity effects. For frequencies above 10(7) Hz, two types of dielectric relaxations corresponding to Na+ motions have been observed.

Dielectric and conductivity studies of V2O5 and sodium aluminogallate performed in a broad frequency range (10kHz-10kHz) have evidenced several relaxations due to interface effects, grains boundaries polarization phenomena, hopping of charged species (ions, electrons). Grains boundaries phenomena are depending on the density and the grains size (microstructure). It has been shown that is possible to determine the real static permittivity and de-conductivity of these polycrystalline materials by using the general effective medium theory of D.S.Mc Lachlan.

Dielectric and conductivity studies have been performed on compacted powders of vanadium pentoxide V2O5 in a broad frequency range 1 kHz-10 GHz, as a function of temperature and density (porosity). The spectra show the existence of relaxation due to grain boundary polarization phenomena. These depend on the synthesis method, i.e., on the microstructure: when the density increases and the average size of the grains decreases the relaxation frequencies increase. Moreover, it has been shown that is possible to determine the real static permittivity and dc-conductivity of polycrystalline V2O5 by taking account of grain boundaries and porosity effects.