A series of polyphenylene derivative polymers with a variety of heterocyclic units along the main chain, and various pendant groups, have been synthesized and their optoelectrochemical properties examined. Polyphenylenes containing electronically isolated emitter centers have optical absorption and luminescence characteristics which are a function of the length of the conjugated unit. A water soluble electroactive rigid-rod poly (p-phenylene), specifically Poly[2,5-bis (propoxy-3-sulfonate)-1,4-phenylene-alt,4-phenylene], has been prepared. Solution cast films of this polymer exhibit optical evidence for bipolarons via both p-type and n-type electrochemical doping. Further poly (p-phenylene) (PPP) derivatives are being pursued, including PPP's bearing pendant donor molecules for charge transfer complex formation. A series of polymers containing alternating p-phenylene units with bithienylene and bifuranylene units, specifically poly[1,4-bis (2-heterocycle)-2,5-disubstituted-1,4-phenylenes], have been synthesized with both alkyl and alkoxy pendant groups. Steric interactions disrupt the ability of the redox doped polymers to attain planarity, strongly affecting the polymer's oxidation potentials and DC conductivities. The substituent length has little effect on the electronic properties of the polymer, but greatly affects the polymer's solubility and transport properties during redox switching.

Chemically synthesized polyaniline films were studied during the doping and dedoping process by imaging the polymer surface using in-situ Atomic Force Microscopy (AFM). The polymer, which was initially in the base non-conducting form was doped using aqueous acidic solutions of both tosylic (pH=0.2) and HCl (pH of 0.2 and 1.0). Dedoping was accomplished by exposing the same doped polymer surface to NH4OH (pH=12) base solution. AFM images showed that it was necessary to cycle the polymer surface 3 times between acid and base before a reproducible surface morphology was established between the doped and dedoped states. For the case of doping with tosylic acid AFM images showed that the polyaniline surface was immediately roughened. In addition there appeared to be an increase in the size of surface channels and cracks. When doping with HC1 (pH=1.0), no change in surface morphology was observed; however, noticeable surface roughening occurred over 10 Minutes for the case of the lower pH=0.2 solution. The complex permittivity and DC conductivity was measured to estimate the level of protonation in the AFM samples.

We demonstrate that a single monolayer of alkyl-trichlorosilane Molecules, covalently grafted to the native oxide of a silicon substrate, allows to fabricate silicon based MIS (Metal-Insulator-Semiconductor) devices with excellent electrical properties. The thickness of the organic monolayer is in the range 1.5–2.8 nm, corresponding to long alkyl chains with 8 to 18 carbon atoms. We have fabricated MIS capacitors with a leakage current density as low as 10-8 A/cm2 at 6 MV/cm, high dielectric breakdown field (12 MV/cm), electrically active defect density lower than 1011 cm-2, and low field dc conductivity as low as 10-16–10-15 Scm-1. Thermal stability has been demonstrated up to 450 °C.

Conducting polymers have novel electrical and optical properties that are potentially useful for applications in electroluminescence display, rechargeable batteries, electrochromic windows, chemical sensors, electromagnetic shielding and anti-electrostatic films. However, these new materials are less adaptable to industrial processes than the traditional synthetic polymers. One of the problems is that conducting polymers are difficult to be solubilized in any solvent, thus lacking solution processability during a manufacturing process. In this article we discuss a new molecular complex of polyaniline that is soluble in water and in polar organic solvents.

Designed synthesis and architectural assembly of head-to-tail polythiophene derivatives provide the ability to control π orbital topology and orbital interactions in conjugated polymers. The preparation of polythiophene derivatives with essentially 100% head-to tail (HT) couplings leads to defect free polythiophenes. These new HT polythiophenes can undergo macromolecular self-assembly to give self-oriented conducting polymers. Study of these materials has led to new insights on structure-property relationships in this class of Materials. In addition, these results show that the molecular orbital overlap, the band dimensionality, and the solid state structure are quite sensitive to the nature of the side chains attached to the polymer's backbone. In addition, we have now synthesized the first heteroatom functionalized HT polythiophenes. These polythiophene derivatives can bind cations, and ion recognition can be used to tune conjugation lengths and properties in polythiophenes. Also presented are a class of random HT coupled 3-alkylthiophenes whose optical and electrochemical properties and possibly electronic properties can be altered by recipe.

The electronic properties of the isomerie (C2S2)n conjugated sulfur containing polymers 1, 2, and 3 were characterized using ab initio and PRDDO Molecular orbital calculations, as well as EH band structure calculations. It is anticipated that such structures might exhibit enhanced electrical conductivities when doped owing to the possibility of the peripheral sulfur atoms extending orbital interactions transverse to the chain axis direction. Such increased dimensionality is demonstrated for the structurally similar superconductive Molecular TTF and ET charge-transfer salts. Of the three polymeric structures, indications are that polymer 2 is highest in energy. Polymer 3 can exist in both “chair” and “boat” conformations, with the chair form slightly more stable. Both the chair and boat forms of 3 were found to be of lower energy than 1. Calculated band gaps and band widths are reported along with preliminary synthetic attempts to prepare these polymers and observed properties.

A new conducting polymer, poly (benzo[1,2-b:4,5-b′]dithiophene-4,8-diyl vinylene) (1), has been prepared by pyrolysis of a precursor polymer 2, which, in turn, was prepared by a multistep synthetic sequence (Scheme 1). The polymer has a UV-vis spectral maximum at 501 nm (2.48 eV), band-gap (band edge) of 1.92 eV and with FeC?3 doping a conductivity of 15 S cm1. Quantum Mechanical calculations using PRDDO, ab-initio and modified extended Hiickel Methodology on the Monomers, trimers and polymers, both aromatic and quinoid, provided structures and an absorption maximum band-gap which is consistent with either a planar aromatic polymer or a polymer which has both aromatic and quinoid units.

Stacked transition Metal Macrocycles [Macm (L)]n with M e.g. Fe, Ru, Os, Co, Rh and Mac = phthalocyanine (Pc) 1,2- or 2,3-naphthalocyanine (1,2-, 2,3-Nc) have been synthesized by us. The bridging ligands (L) are e.g. pyrazine (pyz) or s-tetrazine (tz). In general, these complexes [Macm (L)]n are insoluble in organic solvents, however, soluble oligomers [R4Pcm (L)]n can be prepared using Metallomacrocycles RnPcm, R = t-bu, et, OR, M = Fe, Ru, which are substituted in the périphérie positions.

A systematic investigation of the influence of the bridging ligánds on the semiconducting properties in [Macm (L)]n reveal, that changing L, e.g from dabco over pyz to tz leads to a steady increase of the semiconducting properties without external oxidative doping. Powder conductivities in the order of 0.1 S/cm can be reached by using s-tetrazine, 3,6-dimethyl-j-tetrazine (Me2tz) and others, e.g. fu marodini tri le as the bridging ligands. The intrinsic conductivities are a result of the low oxidation potential of tz and Me2tz and due to the low lying LUMO in the corresponding bridged systems [Macm (tz)]n.

The electrical and physical properties, especially the UV and the Möβbauer spectra for the tetrazine-bridged Macrocyclic Metal complexes are discussed in respect to intrinsic semiconducting properties of these compounds.

The complex dielectric constant ε* (ε* = ε′-iε″) of conducting polymers (polyaniline and poly (3-alkyl thiophene)) is studied over a frequency range spanning from 130 MHz to 20 GHz. The effects of structural parameters (counter-anion size, Molar Mass, length of the alkyl chain on the substituted Monomer) on electrical properties (σdc and ε* values) have been investigated.

In electron beam lithography, charging on photoresist usually causes image distortion and placement error. To dissipate the charge, a conductive polymeric layer can be introduced either over or under the photoresist coating. In this paper, we will discuss the approach of using toluene and xylene soluble polyalkylthiophcne in combination with photoacid generator as a discharge underlayer or interlayer beneath photoresist to dissipate the accumulated charge during li-bcam exposure. We will also discuss the use of water soluble acid or ammonium salt form of poly 3- (cthanesulfonate) thiophene as discharge. toplayer. During the resist image developing process, the toplayer will be removed by aqueous base. Therefore, it is advantageous to use discharge toplayer due to its simplicity. In this study, the salt and acid form of poly 3- (ethanesulfonate) thiophene was synthesized through chemical polymerization of the corresponding methanesulfonate ester. It exhibits the same properties as that of electrochemically synthesized polymer reported in the literature.

Blending polyaniline (PAn) with a host polymer has the advantage of reducing the amount of polyaniline necessary for conductivity, increasing the stability of this conduction, and enhancing the overall mechanical integrity, versatility, and processability of PAn. PAn blends have generally been observed to be immiscible, reducing many of the above mentioned advantages. In this work, PAn was solution blended with poly (vinyl pyrrolidone) (PVP) in either NMP or DMAc, both polar solvents with an amide linkage. We have found PAn to be miscible with PVP under certain processing conditions. The extent of this compatibility and resulting mechanical properties were assessed by DMA, DSC, TGA, SAXS, and light Microscopy. DSC thermograms exhibit a single Tg for all blends ranging from 3 to 30 % by weight PAn. Light Microscopy and SAXS also suggest no phase separation. TGA results show that NMP binds very tightly to both PAn and PVP, with solvent cast blends retaining up to 20 wt% NMP, even after relatively vigorous drying. Electrical conductivity measurements of cast films show conductivity to range from 10-3to 2 S/cm over the same composition range.

We present a general approach for the formation of conducting polymer based sensory materials which employ well-known Molecular recognition elements. These Methods are based upon impeding carrier transport through a conductive polymer's backbone with a barrier or by localizing a carrier with a trap. We have designed polythiophene derivatives which exhibit large changes in bandgap in the presence of specific ions. These Materials are based upon novel crown ether containing bithiophene monomers and we will discuss the details of the synthesis of the monomers and polymers. Sensory polymers which are selective for K+ and Na+ will be described. In such Materials, specific ions induce a twisting of the polymer's backbone.

The doping effects on optical and electrical properties of polysilanes have been investigated by in-situ Measurement. An optical absorption associated with σ–σ* transition was observed near 330 nm for polymethylphenylsilane. By iodine doping, a new absorption was observed at the longer wavelength around 420 nm, which should originate from the charge transfer between dopant and Σ-conjugated system. Similar spectral changes have also been observed for most of investigated linear polysilanes.

Furthermore, we have found drastic spectral change upon iodine doping into polysilane with p-N,N-dimethyIaminophenyI substituent. It has very strong absorption up to 700 nm. It Might originate from a strong interaction between the substituent and iodine. At the same time, Σ-conjugation Might also play a significant role on doping into this system.

A new oxydative-resistant, fusible and processible ethylene/acetylene copolymer has been synthesized. The content of rigid (acetylene) and flexible (ethylene) fragments has been widely varied. The structure of the nascent powders and the films compressed at room temperature have been investigated by SEM and WAXS. DSC has been used for studying the thermal properties. DC conductivity of the iodine doped samples has been measured as a function of temperature. It is shown that the doping leads to arising conductivity in the samples even at 10 Mol % acetylene fragments in copolymer. The conductivity up to 10−3 S/cm is reached for the samples with acetylene fragment concentration about 20 Mol %. It is found that a charge carrier transport in investigated copolymers is caused by doped polyacetylene fragments and described by the hopping Mechanism.

Thin films (18 μ thickness) of ladder polymer poly[(7-oxo-7H,10H-benz (d,e) imidazo (4′,5′:5,6) -benzimidazo (2,l-a) isoquinoline-3,4:10,ll-tetrayl)-10-carbonyl} (BBL), which were cast from an isotropie methanesulfonic acid solution of BBL, were characterized for electrical conductivity in the temperature range of 25–480 °C. The electrical conductivity was Measured in situ while the films were heated at a rate of 2 °C/Minute under vacuum. The in-plane conductivity of BBL films increased rapidly from below 10−10 S/cm at the room temperature to 5 × 10-3 S/cm at 280 °C and then increased slowly to a peak value of 5 × 10-2 S/cm at about 460 °C. The out-of-plane conductivity of the films was comparable to their in plane conductivity at temperatures below 270 °C, however, was lower by a factor of 10 than in-plane conductivity at temperatures above 270 °C. This anisotropy in conductivity of BBL films is discussed with respect to the film morphology determined by wide angle x-ray scattering studies.

2,5-dimethylthio-TCNQ has been newly synthesized, and its optical and electrical properties have been investigated in evaporated films. A high electrical conductivity of σ=2× 10−5 Scm−l has been measured at room temperature. The present single-component system is found to contain 2×1017 spins/cm3. The charge carriers are presumably due to incorporated impurities which give the ESR signals. Carrier hopping is considerably facilitated by close intermolecular S-N contacts between the S atom of the -SCH3 group of one molecule and the N atom of -C≡N group of the neighboring Molecule.

FT-Raman and infrared (IR) spectra of a series of TTF-fluorene derivative family were obtained using a conventional IR spectrometer and a FT-Raman spectrometer. The Raman shifts of the observed band (ν3 stretching band) changes from sample to sample and we correlate these changes with the degree of charge transfer between the donor (TTF) and the acceptor (fluorene derivative) Molecules. These results are compared with those obtained from changes in the IR absorption frequencies of the C≡N stretching mode in the acceptor Molecule.

Thin films of oxotitanium phthalocyanine were grown on optical flat PYREX glass substrates at 0.05 – 1.5 nm/s under 2×l0-4 Pa. The films were analyzed by X-ray diffraction patterns (XRD) and polarized absorption spectra to reveal a preferred molecular orientation in the films evaporated at 0.05 nm/s, but amorphous nature of the films prepared at higher deposition rates. All the films were changed in the crystallinity to α-form Microcrystals upon exposure to vapor of methylene chloride or tetrahydrofuran. XRD analysis of the vapor-treated films at 0.05 nm/s showed only an intense peak at 2θ = 7.50°, demonstrating that the (010) face of the α-form crystal is highly oriented perpendicularly to the substrate surface. The Molecular orientation was again demonstrated by polarized absorption spectra. The photoconductive behavior of the films was found to depend on the deposition rates as well as on the vapor treatment.

We report our results for the temperature dependence of the Hall coefficient and in-plane resistivity for the asymmetric-donor-based quasi-2D Molecular crystal τ- (P-S,S-DMEDT-TTF)2 (AuBr2)1(AuBr2)y (y≈0.75). Using a recent “geometrical representation” of the weak-field 2D Hall conductivity developed by N.P. Ong [Phys. Rev. B 43, 193 (1991)], we model the temperature dependence of these electronic transport properties in terms of the temperature dependence of the scattering path length and its anisotropy along the 2D Fermi surface.

A series of new stable fiinctionalised aryl ethynyl compounds bearing nitronyl-nitroxy and galvinoxyl radicals were synthesised as potential organic magnets with optical properties. Our goal is to construct biradicals in linear or broken rod molecules with the aim of probing i) the efficiency of the conjugation for the intramolecular spin exchange, and / or ii) the inter-Molecular Magnetic interaction between the neighboring radicals in the solid state Materials.

We focused our attention on the preparation of phenoxy, and galvinoxyl biradicals of the conjugated phenyl and thienyl diethynyl Moieties. The synthesis of these new components will be presented. Their optical and magnetic properties will be discussed both in solution and in the solid state.