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Thin films of new pyrrolo [ 1 , 2 - a ] [ 1 , 10 ] phenanthroline derivatives have been investigated by ultraviolet photoelectron spectroscopy, with a view of future applications in optoelectronic devices. The electronic band structure of investigated compounds (for electron energies ⩽ 25 eV ) is to a great extent determined by substituent (R = NO 2 , Cl) induced transformations of molecular orbitals.

The investigation of conversion of new soluble poly( p -phenylenevinylene) (PPV) precursor and PPV patterns by irradiation with UV light of a film is reported. We obtained patterns by this method with well-defined edges and channel width up to 10 μm. Also, it was found that the PPV precursor polymer is a photoresist material. This allows the fabrication of PPV patterns, which can directly act as luminescent structures in organic light-emitting diodes (OLEDs). Using the atomic force microscopy (AFM) technique, investigations on the PPV thin films show that at 200 °C well-defined crystalline domains of PPV are detected, thus indicating the complete transformation of the precursor into the final polymer. The current–voltage characteristics of single and double PPV layer devices indicate that turn-on voltages around 9 and 8 V were recorded for double and single PPV layer devices, respectively. From the electroluminescence–voltage plot, an onset voltage at 10 V is detected for two PPV layers OLED. In addition, we investigate the optical, electrical and EL characteristics of pyrrolo[1,2-a][1,10]phenanthroline derivatives [Leontie L, Druta I, Danac R, Rusu GI. Synth Met 2005;155/1:138; Zugravescu I, Petrovanu M. 3+2 Dipolar cycloaddition. Bucharest: Roman Academic Publishing House; 1987 [in Romanian]; Druta I, Andrei M, Aburel P. Tetrahedron 1998;54:2107; Druta I, Dinica R, Bacu E, Humelnicu I. Tetrahedron 1998;54:10811; Dinica R, Druta I, Pettinari C. Synlett 2000;7:1013; Danac R, Rotaru A, Drochioiu G, Druta I. J Heterocyclic Chem 2003;40:283; Druta I, Danac R, Barbieru R, Tapu D, Andrei M. Sci Ann Al I Cuza Univ Iasi S Chem 2001;IX:149] as potential candidates for OLED applications. In this case, PPV was used as the hole-transport layer (HTL) and pyrrolo[1,2-a][1,10]phenanthroline derivatives, which were spin coated onto PPV, as the emissive layer. The structure of all PPV devices reported in this paper was fabricated using UV light for patterning.

The temperature dependence of d.c. electrical conductivity, σ , and Seebeck's coefficient, S , for seven new synthesized 1-( p -R-benzoyl)-1,2,3,3 a -tetrahydropyrrolo-[1,2- a ][1,10]-phenanthrolin-2,3-( N -R′)-dicarboximide compounds, has been investigated. Thin film samples ( d = 0.09–0.94 μm) deposited from dimethylformamide solutions, by an immersion technique, onto glass were used. X-ray diffraction (XRD) analyses were performed for the investigation of crystalline structure of as-prepared films, while atomic force microscopy (AFM) technique, corroborated to optical microscopy was used for the examination of surface morphology. The behavior of σ and S as a function of temperature is typical for polycrystalline semiconducting (n-type) materials. The activation energy of electrical conduction laid in the range 1.21–1.82 eV, while the ratio of charge carrier mobilities ranged between 1.05 and 1.15. Some correlations between semiconducting properties and molecular structure of the compounds were established. The model based on band gap representation can be satisfactory used for the explanation of electronic transport in investigated compounds.

Temperature-dependent d.c. electric conductivity of some recently synthesized organic compounds, stable disubstituted 4-(4-pyridyl)pyridinium ylides, is studied. Thin-film samples ( d = 0.100.80 μm) spin-coated from dimethylformamide solutions onto glass substrates have been used. Organic films with reproducible electron transport properties can be obtained if, after deposition, they are submitted to a heat treatment within temperature range of 297 − 527 K. The studied polycrystalline compounds exhibit typical n -type semiconductor behavior. The activation energy of the electric conduction ranges between 0.59 and 0.94 eV. Some correlations between semiconducting parameters and molecular structure of the organic compounds have been discussed. In the higher temperature range ( T > 400 K), the electron transport in examined compounds can be interpreted in terms of the band gap representation model, while in the lower temperature range, the Mott's variable-range hopping conduction model was found to be appropriate. Some of the investigated compounds hold promise for thermistor applications.

We discuss in this progress report whether the surface investigations, means by ellipsometry, atomic force microscopy, spectroscopy and profilometry of Teflon (polytetrafluoroethlylene - PTFE) thin films deposed by electron sputtering in vacuum on different materials. The substrates materials can be used in bioengineering and medicine applications. We found that the surface morphology and structures properties of Teflon thin films depend of parameters selected in deposition process as deposition rate, substrates temperature, deposition temperature, electron activation energy. This study can be used to improve new medical applications and new optoelectronic devices. Recent reports in transfer cold friction of Teflon thin film layers are discussed in the context of material requirements for such special applications because the formation of or oriented networks gives new benefits of the surface obtained.

Thermally stimulated processes have been studied in thin films of phenanthroline derives to describe the states that had been localized. Ultraviolet Photoelectron Spectroscopy had checked out before thin films of new pyrrolo[l,2-a][l,10] phenanthroline derivatives [1], in order to further applications in optoelectronic devices. The investigated compounds have an electronic band structure which is due to the substituent (R=NO2, Cl) induced transformations of molecular orbitals. Thermally stimulated discharge currents (TSDC) attested dipolar and charge transport mechanisms. Each TSDC peak has been assigned to elementary processes that are different utilizing in addition dielectric spectroscopy (DES), and the mean trap depths have been approximated from thermally stimulated luminescence (TSL) curves.