Based upon the concept of charge carrier hopping within a disordered organic solid a formalism for the temperature and field assisted charge injection from an electrode into an organic dielectric has been developed. Both back flow of charges towards the injecting electrode and the dependence of the injection efficiency upon the charge carrier mobility has implicitly been taken care of. Experimental results for electrode limited injection are in good agreement with the theory.

The effect of pre-crystallization pulsed magnetic field (PMF) treatment of linear flexible-chain polymers on kinetics of their crystallization and structure in the crystalline state has been studied in polydimethylsiloxane (PDMS) and polyethylene oxide (PEO). It was established that the PMF treatment can destruct the initial net of non-chemically bonded “physical nodes” of the polymer and thus turn the melt into a metastable state with the increased sensitivity to regimes of crystallization. The effect revealed can lay the foundation for the development of new effective methods of controlled crystallization of the flexible-chain polymers, including fractionation and crystallization of polymorphic polymers in the chosen structural modification.

For the last years, especially after the creation of conducting polymers, much prominence has been given to the works on creation and working out the new technologies of implantation of different metals and, on the whole, inorganic components into the structure of different polymers.

Of special interest are rapidly developing researches in the field of creation and application of different nanomaterials also including metals in the processes of synthesis of different polymers.

The data on electrophysical properties of polyvinyl acetate with doping amorphous molybdenum, obtained for the first time in SPE “ATOM” of Armenia, are being presented and discussed for the first time in the given paper.

It is shown, that the dopes of amorphous nanosize molybdenum and crystalline nanosize molybdenum in the process of polymerization lead to its implantation into the structure of polymer. Amorphous molybdenum practically always lowers substantially electrical resistance of composite materials.

Compressive stresses in thin capping films deposited onto low-k dielectric substrates are particularly prone to relaxation through buckling. This is due to insufficient cap/low-k film adhesion energy and to the compliance of low dielectric constant films. Low-k dielectric films, especially when porous, have low elastic modulus and demonstrate poor adhesion to other layers.

When adhesion is poor the cap film can locally buckle as if unconstrained. The buckle front can propagate like a crack and lead to complete delamination of the cap layer. If the cap/low-k film adhesive energy is high, wrinkling instabilities can take place under specific conditions determined by the geometry and the mechanical properties of the stack. In this case the dielectric also deforms due to stress relaxation. A theoretical and experimental evaluation of the parameters influencing the occurrence of these instabilities is presented. This study was carried out to explore the application and reliability of low-k materials as dielectrics for advanced interconnects.

Organic electroluminescence (EL) single layer devices using electroactive dyes incorporated in poly-vinylcarbazole (PVK) were fabricated. The molecular structures of the two-photon dyes are the generic D-π-A;, D-π-D, and A-π-A;, structural motif, composed of a diphenylamine donor (D), a distyrylfluorene π-bridge, and an oxadiazole acceptor (A). A single layer type of EL device of ITO/PVK:DYE/Ca/Al was fabricated. The light emission peak and the threshold of the electroluminescence emission depend on the structure and concentration of the dye. The EL intensity increases with the dye concentration and it was found that as the voltage is increased the brightness increases and reaches a value 498 cd/m2 at an applied voltage of 25 V for the D-π-A; dye. We present a physical explanation of this observed behavior and show that this has significant impact on the design of light emitting devices using these organic dyes.

PET-steel interfaces were studied with FTIR. Differences in conformations of PET in free standing films and supported films in laminates are attributed to the presence of the PET-metal interface. These differences could be accentuated by varying the physical environment ie. by annealing or mechanically loading both free and supported films.

We present microscopic study of electronic and transport properties of single molecules sandwiched between two metallic contacts using Green's function based modeling approach within both ab initio and self-consistent semi-empirical framework. The methods are applied to thiol-based organic molecules and finite-size single-wall carbon nanotubes respectively. Results on electrostatics, transmission and current-voltage characteristics are presented.

Novel diamine monomers, containing fluorine and phosphine oxide - bis(3-aminophenyl)-3,5-bis(trifluoromethyl)phenyl phosphine oxide (mDA6FPPO) and bis(3-aminophenyl)-4-(trifluoromethyl)phenyl phosphine oxide (mDA3PPO) - were utilized to prepare polyimides with dianhydrides such as 6FDA, BTDA or ODPA by the conventional two-step route, i.e., preparation of poly(amic-acid), followed by solution imidization. Adhesion property of the polyimides was evaluated via a peel test with bare Cu foil, as well as Cr/silane coated Cu foils, and failure surfaces were analyzed by SEM/EDX to elucidate the adhesion mechanism. The polyimides with 3FDAm exhibited the highest Tg, followed by mDAPPO-, mDA3FPPO- and mDA6FPPO-based polyimides, but the mDAPPO-based polyimides exhibited the highest adhesion properties, followed by mDA3FPPO, mDA6FPPO, mDDS and 3FDAm, attributing to phosphine oxide and fluorine moieties.

Electrical impedance spectroscopy is used to show that time-dependent charge trapping processes occur in double-layer polymer light-emitting diodes based on poly(ethylene-dioxythiophene):poly(styrene sulfonic acid) (PEDOT:PSS) and poly(p-phenylene vinylene) (PPV). No time-dependent charge trapping processes are observed in single-layer devices based on PPV only. Furthermore, in double-layer devices based on poly(2,7-spirofluorene) (PSF) instead of PPV, such processes are also absent. Traps are probably created in the PPV layer close to the PEDOT:PSS interface due to chemical reactions that occur specifically between PEDOT:PSS and PPV.

Atomic force microscopy observations of the fine structure of cracks have been carried out on Nickel thin films on polyimide substrates under tensile test. For strains of the order of 10%, the cracking of the metallic thin film induces notable damaging of the polymeric substrate. Post-mortem observations of the substrate and finite element simulations of the stress field at the cracks head have been performed to characterize this unexpected damaging: the crack propagation at the film/substrate interface and inside the substrate.

The goal of this research was to determine the molecular structure of interfaces between plasma polymerized acetylene films and steel substrates and to elucidate the mechanisms by which the films adhere to the substrates. Inductively-coupled, RF-powered plasma reactors interfaced to an FTIR spectrometer and to an XPS spectrometer were used to deposit films ranging in thickness from a few tens of nanometers to approximately one nanometer onto polished steel substrates. As the thickness of the films was decreased, features in the XPS and FTIR spectra that were characteristic of the bulk of the films decreased in intensity and features characteristic of the interface increased in intensity. A band was observed near 1706 cm−1 in FTIR spectra of the thickest films and attributed to carbonyl groups. Bands were observed near 1600 and 1045 cm−1 in spectra of the thinnest films and attributed to iron carboxylate and iron alkoxide groups that were responsible for adhesion of the films to the substrates. Oxygen required to form these groups was available from water or oxygen molecules adsorbed onto the walls of the reactor.

There are a vast number of organic compounds that could be considered for use in molecular electronics. Because of this, the need for efficient and economical screening tools has emerged. We have demonstrated that the substituent parameter values (σ), commonly found in advanced organic chemistry textbooks, correlate very strongly with features of the charge migration process. This result supports the use of the σ values as a low cost time saving tool in the selection of compounds for use in molecular electronic devices.

We have studied defect structures in the crystalline organic molecular semiconductor pentacene. Our investigations included the calculation of free surface energies on low index planes. It was found that that the (001) surface had the lowest energy ∼50 mJ/m2, roughly half that of the other low index planes, (100) and (010) ∼120 mJ/m2 and ∼140 mJ/m2 respectively. These calculations were then compared to experimental data from vapor grown crystals using optical microscopy, Scanning Electron Microscopy (SEM) and High Resolution Transmission Electron Microscopy (HRTEM). We also modeled dislocations dipoles of varying Burgers vector and dipole length. It was found that dislocations were accommodated by extensive molecular deformation near the defect core, as well as a well defined stacking fault that occurred down the length of the dipole. Finally, we investigated low angle tilt grain boundaries. It was seen that low angle boundaries relaxed through molecular deformation in the first layer of molecules at the boundary as well as bending of the (001) planes.

We have investigated interface effects in C60/Cu-oxide/Cu structures. C60 thin films were grown under high vacuum by thermal evaporation and the well-known “pentagonal pinch mode” of C60, Ag(2) band was examined by Raman spectroscopy. We observe Raman-active bands centered at 1420, 1448, 1455, and 1465 cm−1 in C60/Cu-oxide/Cu samples with a thin (∼40 nm) C60 overlayer. The 1420, 1448, and 1455 cm−1 Raman bands are not observed in the spectra of pristine C60 powder, copper-oxide substrate, and C60/Cu-oxide/Cu samples with thick (∼1.3 μm) C60 overlayer. We associate these new Raman-active bands with C60/copper-oxide interface.

Electro-optic polymer thin-films were characterized at microwave frequencies, for possible applications in GHz modulators. Single layers of the polymers were spin coated on low loss magnesium oxide substrates for characterizing the polymers at microwave frequencies. Coplanar waveguide test structures were designed for evaluation of the relative dielectric permittivity as well as the loss-tangent of the polymers at microwave frequencies. A conformal mapping technique was used for the extraction of relative dielectric constant of the polymer films based on the microwave scattering parameter measurements. As an example, a DR1-PMMA polymer had a relative dielectric permittivity of 3.01 and a loss-tangent of 0.075 at 8 GHz. The design of the test structures, the procedure for the accurate determination of the dielectric permittivity and the loss-tangent of the polymer films are discussed in this paper.

Although integrated circuit design principles are well understood, they lead to the possibility of radically new modes of device operation when applied to conjugated polymers. Design for speed is very important, even when this is not a primary requirement for a particular application, since supply voltage can be reduced and with it power dissipation. For all-polymer circuits, on thermally insulating plastic substrates, device operating temperature will also be reduced. This has implications for device stability. There are a number of factors that are important in increasing circuit speed. Reduction of channel length must be accompanied by a reduction of gate overlap capacitance and this makes the conventional versions of bottom gate TFT perform badly. Vertical devices are a particularly attractive proposition providing that off-currents can be maintained at a low level. One approach is to use Schottky barriers as the source and drain. Examples will be explained, as will the very unusual mode of operation of such devices. Optimum load structures will also be defined.

The effect of defects introduced by high-energy electron irradiation on microstructure and properties in poly(vinylidene fluoride- trifluoroethylene) [P(VDF-TrFE)] is reported. In studies of the copolymers, it is found that as defect concentration increases, the material can be changed from a normal ferroelectrics to a relaxor ferroelectrics (RFE) and then to a simple relaxor. Correspondingly, the crystalline morphology changes from a coexistence of polar and non-polar phases to a macroscopically uniform non- polar phase, as revealed by x -ray data. It was observed that the dielectric property in the copolymers with a different amount of defects was well described by the Vogel-Fulcher (V-F) relationship. Based on the experimental data, a critical size, which is the smallest size of crystal with ferroelectric phase, of about 5 nm was obtained for the copolymer. The RFE developed here exhibits a massive electrostrictive strain which is very attractive for many actuator and transducer applications and a high dielectric constant which is attractive for development of high- density energy storage capacitors and electronic packaging.

Cu/C films were prepared at room temperature under Cu(hfac)2-Ar-H2 atmosphere in order to obtain metallized polymer by using ECR-MOCVD (Electron Cyclotron Resonance Metal Organic Chemical Vapor Deposition) coupled with periodic DC bias system. Room temperature MOCVD was possible when periodic negative voltage was applied on the polymer substrate. The periodic negative voltage induces ions and radicals to have nucleation reaction on the surface of the substrate. Formation of Cu/C films strongly depends on the periodic negative pattern of DC bias and the electric sheet resistance of the films was controlled from 108 to 100ohm/sq ranges by process parameters such as microwave power and magnet current. The increase in microwave power and magnet current brought on copper-rich film formation with low electric resistance. On the other hand carbon-rich films with high sheet electric resistance were prepared with decreased values for process parameters aforementioned.

The shear activation volumes of miscible polystyrene-poly(2,6-dimethyl-1,4-phenylene oxide) (PS-PPO) blends at different PS-PPO ratios were determined experimentally by both plane strain and uniaxial compression at constant strain rates. We find that the same correlation between the shear activation volume and the entanglement density ρe holds for the blend as well as for various pure glassy polymers: . Since the shear activation volume is closely related to the size of the plastic shear zones, this correlation suggests that the cooperativity of the elementary processes of plastic deformation in glassy polymers scales with the entanglement density.

Conjugated polymer Schottky diodes have been directly written onto glass and alumina substrates. The rectifying contact was made between the p-type semiconductor poly(3,4-ethylene-dioxythiophene) doped with polystyrene sulfonic acid and Zn. The devices exhibit rectification ratios in the range of 102:1 to 103:1 at biases of ±1 V and ±10 V, respectively. The devices demonstrate rectification at frequencies up to 250 kHz. A full-wave bridge rectifier circuit written onto a glass substrate converts ac to dc up to 250 kHz and ±5 V.