Highly conjugated acrylate-functionalized polythiophenes from anodic coupling of thiophene- and bithiophene-hexyl acrylates

Anodic coupling of thiophene- (1) and cyclopentadithiophene- (2) hexyl acrylates in acetonitrile to polythiophenes is reported. The resulting polymers have been characterized by cyclic voltammetry, UV–vis and FTIR spectroscopy and in-situ conductivity. The produced polythiophene films, for which FTIR analysis show that the acrylate moiety is kept unchanged, display high conjugation lengths (λ_max=520 (1) and 600 (2) nm) and conductivities (20 (1) and 100 (2) S cm⁻¹).     

Electrical conductivity of organosilicon polymers II: Synthesis and electrical conductivities of iodine-doped polysilanes containing amino groups

A series of polysilanes containing an N,N-dimethylaminophenyl group and N-pyrrolyalkyl group as in the side chain were prepared by the Wurtz coupling polymerization. The polymerization of N-pyrrolylbutyl or N-pyrrolylhexyl-substituted dichlorosilane with sodium gave successfully the polysilanes with higher molecular weight than 10⁵. The electrical conductivities of I₂-doped polysilanes were dependent on the chemical structure of the amino side chain. Moreover, by use of excess iodine, the conductivity of the polymer was enhanced. The electrical conductivity of poly[bis(6-(N-pyrrolyl)hexyl]silane] (7a) increased to a maximum value of 8 × 10⁻² S/cm.     

Synthesis and properties of aromatic amine-bridged phthalocyaninatoruthemum(II) coordination compounds

Phthalocyaninatoruthenium(II) (PcRu) was reacted with aromatic amines 1–5 to form polymers 6–10. The products were characterized spectroscopically and were oxidized with iodine. The oxidized products 6′–10′ have conductivities in the region of 10⁻⁴ S cm⁻¹.     

AlCl3-assisted formation of charge-transfer complexes between polyacetylene and tetracyanoethylene,TCNE

Polyacetylene, (CH)_x, the simplest conjugated polymer, can be converted into a conducting materials (8 Ω⁻¹ cm⁻¹) by treating it with TCNE/ AlCl₃/benzene solution. An electron transfer π-complex was obtained, as shown by EPR and XPS spectroscopies.     

In situ conductivity and photoconductivity measurements of polyaniline films

In situ conductivity measurements on a polyaniline film with a fourprobe electrode are performed in NH₄F, 2.3HF and in propylene carbonate in the dark and under illumination. The conductivity is also determined on a pellet of chemically prepared polyaniline mixed with carbon black as for a battery electrode. The upper values of conductivities are 120 ohm⁻¹ cm⁻¹ in the hydrofluoric medium, 25 ohm⁻¹ cm⁻¹ in propylene carbonate and 8 ohm⁻¹ cm⁻¹ in the solid dry state. For a pellet with 20% carbon black it is 0.5 ohm⁻¹ cm⁻¹. The increase in conductivity of the polyaniline film in the solid state upon illumination is about 0.7 ohm⁻¹ cm⁻¹ (10%).     

Synthesis,crystal structure and electrical properties of [Pd(dmit)2]2− and [Pd(dmit)2]0.5− anion complexes with 2-dimethylamino-1,3-dithiolanylium as counter cation

The synthesis, structural characterization and electrical conductivity measurement of [MDA]₂[Pd(dmit)₂] (1 and [MDA] [Pd(dmit)₂]₂ (2) (MDA = 2-dimethylamino-1,3-dithiolanylium, dmit = 1,3-dithiole-2-thione-4,5-dithiolate) are reported. Complex 1 consists of two Pd(dmit)₂ anions and four MDA cations in the unit cell and the anions are separated by cations in the crystal; the conductivity is about 10⁻⁷ S cm⁻¹. The structure of complex 2 is made of stacked Pd(dmit)₂ dimers. The modes of intra- and inter-dimer molecular overlapping are both of slide-away types. Pd atoms deviate from planes formed by four ligand S atoms 0.07 Å apart to approach each other. Room-temperature conductivity is 10–70 S cm⁻¹. Temperature-dependent conductivity measurement of this compound indicated that it is a semiconductor with a low activation energy (0.043 eV).     

Quantitative optical study of I2-doped polyacetylene

The relation between dopant concentration and adsorption spectra of iodine-doped polyacetylene films is studied quantitatively with films whose iodine contents are analysed by radioactivation analysis. It is shown that the dopant content of thin polyacetylene film can be estimated from the absorption spectra. For heavily iodine-doped film, optical constants are determined from measured infrared, visible and ultraviolet spectra by the aid of the Kramers–Kronig relation. The absorption coefficient of 64% iodine-doped film at the absorption maximum of the mid-gap band, 7500 cm⁻¹, is 2.5 × 10⁵ cm⁻¹ and that of the same film at the adsorption maximum of the pentaiodide ion, 19 000 cm⁻¹, is 2.9 × 10⁵ cm⁻¹, whereas the maximum value for undoped film at 18 500 cm⁻¹ is 1.5 × 10⁵ cm⁻¹ (cis-rich form).     

A thermally resistant and air-stable n-type organic semiconductor: Naphthalene diimide of 3,5-bis-trifluoromethyl aniline

We report a thermally resistant and air-stable n-type semiconductor based on our study of naphthalene diimide (NTCDI) derivatives (N1, N2, and N3) with various numbers of electron-withdrawing CF₃ groups. The device using N3, which contains aromatic NTCDI, was found to exhibit an electron mobility (μ_e) of 0.15 (±0.04) cm²/V s (the maximum μ_e observed was 0.24 cm²/V s) and an I_on/I_off (at V_d = 80 V) of approximately 2 × 10⁵. Moreover, the N3 device exhibits excellent air stability, even when exposed to the open air for 42 days, and significantly better thermal resistance than the previously reported benzylic imide derivative R1.     

Synthesis and electrical conductivities of charge-transfer complexes of bis(vinylenedithio)tetrathiafulvalene and its methyl derivatives with strong acceptors

Charge-transfer complexes of bis(vinylenedithio)tetrathiafulvalene (VT), bis(methylvinylenedithio)tetrathiafulvalene (DMVT) or bis(dimethylvinylenedithio)t tetrathiafulvalene (TMVT) with several strong acceptors, such as TCNQ, F₄TCNQ, DDQ, TCNE, Bu₄NBr₃ and I₂, were synthesized by leaving the mixed solution of a donor and an acceptor to stand at ambient temperature. Not only the usual 1:1 (donor:acceptor) complexes but also 2:1, 1:2, 3:1, 3:2 and 5:2 ones were obtained. Unfortunately, a single crystal of good quality was not obtained. The electrical conductivities of the compressed pellet samples were measured by van der Pauw's method. Most of them showed high conductivities of 10⁰–10⁻¹ S cm⁻¹ at room temperature. However, the TCNQ complexes were insulators. The electrical conductivities could be explained on the basis of the i.r. spectra of the complexes and the redox potentials of the donor and acceptor molecules.     

Solid-state photoelectrochemical device using poly(o-methoxy aniline) as sensitizer and an ionic conductive elastomer as electrolyte

We report on a photoelectrochemical cell based on polymers (electrolyte and sensitizer) and TiO₂. Poly(epichlorohydrin-co-ethylene oxide) filled with NaI/I₂ was used as electrolyte and poly(o-methoxy aniline) doped with p-toluenesulfonic (PoAni-TSA) as dye. The short-circuit current and open-circuit voltage obtained with illumination at 120 mW cm⁻² are 12.2 μA cm⁻² and 0.048 V, respectively, indicating that the ionic conductive elastomer is appropriated for assembling a totally solid device. The monochromatic photon-to-current conversion efficiency decreases from 1.3% to 0.1%, from 410 to 600 nm, respectively, showing that the conducting polymer acts as a dye for TiO₂, injecting electrons into its conduction band.     

Infrared absorption in K-doped (CH)χ

The infrared absorption of polyacetylene doped with high concentrations of potassium has been studied. The samples, doped by a vapor-phase technique to y≈0.08 and y≈0.18, showed doping-induced infrared absorption at ∼900, 1270, and 1390 cm⁻¹ which was comparable in strength to that seen in [CH(ClO₄)_y]_χ with y≈0.06. These experiments were motivated by calculations of the infrared absorption which showed that whereas there are only small differences in the infrared spectra for isolated solitons and isolated polarons there is a dramatic difference between the high-concentration polaron lattice and soliton lattice. The shapes of the absorption spectra are rather similar but the absorption for the polaron lattice is 13 orders of magnitude weaker than that of soliton lattice. The observation of these features at high doping levels appears to be inconsistent with the polaronic metal and strongly disordered Peierls insulator models for highly doped polyacetylene.     

Annealing behaviors of vacancy in varied neutron irradiated Czochralski silicon

The difference of annealing behaviors of vacancy-oxygen complex (VO) in varied dose neutron irradiated Czochralski silicon: (S1 5×10¹⁷ n/cm³ and S2 1.07×10¹⁹ n/cm³) were studied. The results show that the VO is one of the main defects formed in neutron irradiated Czochralski silicon (CZ-Si). In this defect, oxygen atom shares a vacancy, it is bonded to two silicon neighbors. Annealed at 200 °C, divacancies are trapped by interstitial oxygen(O_i) to form V₂O (840 cm⁻¹). With the decrease of the 829 cm⁻¹ (VO) three infrared absorption bands at 825 cm⁻¹ (V₂O₂), 834 cm⁻¹ (V₂O₃) and 840 cm⁻¹ (V₂O) will rise after annealed at temperature range of 200–500 °C. After annealed at 450–500 °C the main absorption bands in S1 sample are 834 cm⁻¹, 825 cm⁻¹ and 889 cm⁻¹ (VO₂), in S2 is 825 cm⁻¹. Annealing of A-center in varied neutron irradiated CZ-Si is suggested to consist of two processes. The first is due to trapping of VO by O_i in low dose neutron irradiated CZ-Si (S1) and the second is due to capture the wandering vacancy by VO, etc, in high dose neutron irradiated CZ-Si (S2), the VO₂ plays an important role in the annealing of A-center. With the increase of the irradiation dose, the annealing behavior of A-center is changed.     

The effect of a novel organic compound chiral macrocyclic tetraamide-I interfacial layer on the calculation of electrical characteristics of an Al/tetraamide-I/p-Si contact

The Al/tetraamide-I/p-Si Schottky barrier diode (SBD) has been prepared by adding a solution of a novel nonpolymeric organic compound chiral macrocylic tetraamide-I in chloroform on top of a p-Si substrate and then evaporating the solvent. It has been seen that the forward-bias current–voltage (I–V) characteristics of Al/tetraamide-I/p-Si SBD with a barrier height value of 0.75 eV and an ideality factor value of 1.77 showed rectifying behaviour. The energy distribution of the interface state density determined from I–V characteristics increases exponentially with bias from 5.81 × 10¹² cm⁻² eV⁻¹ at (0.59-E_v) eV to 1.02 × 10¹³ cm⁻² eV⁻¹ at (0.40-E_v) eV. It has showed that space charge limited current (SCLC) and trap charge limited current (TCLC) are the dominant transport mechanisms at large forward-bias voltages.     

Field effect transistor using poly(o-metoxyaniline) films

A thin-film transistor (TFT) with good carrier mobility and environmental stability has been fabricated using poly(o-metoxyaniline) (POMA) as the active layer. The carrier mobility has been determined to be approximately 2×10⁻⁴ cm² V⁻¹ s⁻¹, for the best transistors with low conductivity (<10⁻⁷ Ω⁻¹ cm⁻¹). High dynamic ranges have been found, with source–drain currents varying four orders of magnitude with different gate voltages.     

Multi-component molecular conductors with supramolecular assembly based on ET radical cation salts with (NO3)− anion

Synthesis, structure and conducting properties of two new multi-component radical cation ET salts with the (NO₃)⁻ counterion: (ET)₂(NO₃)·C₂H₄(OH)₂ (I) and (ET)₂(NO₃)·0.5[C₂H₄(OH)₂]·H₂O (II) are described. Both salts have layered structures with the distinguishing feature of hydrogen bonds being present between the radical cation layers and anion sheets. It was found that introduction of glycol molecules to compositions of I and II significantly affects the structure of their cation and anion layers and, as a result, their conducting properties. I is a semiconductor, while II demonstrates metallic conductivity down to 4.2 K.     

Optical study on bis(propylenedithio)tetrathiafulvalenium (BPDT-TTF) salts

Polarized reflectance spectra of (BPDT-TTF)₃(PF₆)₂ and (BPDT-TTF)₂I₃ were measured at room temperature over the spectral region from 720 cm⁻¹ to 25 000 cm⁻¹. Both of these salts exhibited one-dimensional behaviour in contrast to the BEDT-TTF (bis-(ethylenedithio)tetrathiafulvalenium) salts. The transfer integrals and the on-site Coulomb energy of these materials were estimated by analysing the optical spectra, and the on-site Coulomb energy of (BPDT-TTF)₃(PF₆)₂ was found to be significantly larger than that of TCNQ salts.     

Resonant Raman scattering of Er3+ doped and partially isomerized polyacetylene

The results of experimental studies of resonant Raman scattering (RRS) spectra from Er³⁺ implantation doped and partially isomerized polyacetylene are presented. Thin cis-(CH)_x films were synthesized by the method of rare earth complex catalysis polymerization. Doping technique is ion implantation. The surface density of implanted Erbium ion is about 5×10¹³/cm². In the case of cis-(CH)_x, RRS bands at 1160, 1270 and 1540 cm⁻¹ have been observed λ_L = 488 nm (10K) and it was shown clearly that a shift in frequency of the peaks assigned to the remaining trans segments occurs during the isomerization process. In the case of Er³⁺ doped cis-(CH)_x, Er³⁺ induced Raman bands at 1145, 1320 and 1510 cm⁻¹ have been measured (λ_L = 488 nm, RT) for the first time and it is observed that the Raman bands from Er³⁺ doped trans/cis-(CH)_x are shifted to lower frequencies. We point out that the effect of Er³⁺ dopant is associated with the defects.The experimental results are discussed by using the model based on the hypothesis that the sample properties can be interpreted in terms of a bimodal distribution of long and short conjugation length segments (for trans-(CH)_x) and the bipolaron microscopic model on the basis of multi-phonon lattice relaxation theory (for cis-(CH)_x). Our studied results support further the bimodal distribution model and the bipolaron microscopic model.     

Polymerization of dicarbonyl(η5-cyclopentadienyl) (η1-pyrrolyl)iron(II) : A new class of conducting polymers

Force field and semi-empirical MO calculations are used to predict the behavior of dicarbonyl(η⁵-cyclopentadienyl) (η¹-pyrrolyl)iron(II) (Fp-pyr, 1) under conditions commonly used to polymerize pyrrole. We also discuss similar calculations which were performed on a hypothetical tetramer. Details of chemical and electrochemical oxidations of 1 are presented, as well as thermal and spectroscopic analyses of the products. The product of the electrochemical oxidation does not appear to be electrically conducting, but those from the chemical polymerization have conductivities ranging from 5.2 × 10⁻⁵ to 2.5 × 10⁻¹ S/cm.     

Mass spectrometric characterization of halogen doped polyacetylene

Mass spectrometry was used to investigate the volatile species given off when polyacetylene, which had been exposed to I₂, Br₂, Cl₂, or F₂, was heated in vacuo. A correlation of the conductivity of the samples with the amount of molecular halogen ions (X₂⁺) evolved was observed. These results are consistent with the present concept for the form of the dopant in the polymer. In the I₂ case, two sources of iodine in the (CH)_xwere found and these were related to the presence of I₃^? and I₅^? in the polymer films.     

Polyene films prepared by poly(ethylene glycol)s-catalyzed dehydrochlorination of poly(vinyl chloride): chemical and electrochemical properties

Poly(vinyl chloride) (PVC) film containing certain amounts of poly(ethylene glycol)s (PEG) catalyst can be extensively dehydrochlorinated by aqueous potassium hydroxide. The molar mass of the PEG used as phase transfer catalyst is ranged from 200 to 800 g mol⁻¹. According to the results of elemental analysis and UV–visible, Fourier transform-infrared (FT-IR) and FT-Raman spectra, the polyene films obtained from these systems are polyacetylene-like and contain relatively long conjugated sequences. The highest conversion of the reaction at room temperature is measured to be about 90% (f_H). The conductivity of iodine-doped polyene films can reach to the order of 10⁻² S cm⁻¹. The electrochemical doping process of dehydrochlorinated PVC film is controlled by diffusion mechanism like polyacetylene, and some irreversible degradation at the polyene surface occurs when the potential is rising above 1.6 V.