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Stable Schottky barrier diodes with tetracyanoquinodimethane doped with 5% by weight bis(β-naphthyl)-tetrathiafulvalene as active ndoped semiconductor have been fabricated by physical vapor deposition. Gold and aluminum were used as ohmic and Schottky contacts, respectively. An ideality factor of 3.5 was deduced from current-voltage measurements. Several cycles of voltage sweeping were necessary before the diodes showed optimal characteristics. Charge migration is most likely the dominating mechanism behind this phenomenon. From capacitance-voltage measurements, at different frequencies, a charge carrier concentration of 2.2 × 10 16 cm −3 was determined. A high charge carrier mobility of 14 cm 2 V −1 s −1 was deduced. These devices showed no degradation after a month of storage in a laboratory environment.

Bithiophenes, when used as starting material for polythiophene synthesis, offer advantages over corresponding thiophenes. Polymerization proceeds at lower oxidation potentials and lower monomer concentration and gives polymers with higher yield and better regularity as shown by cyclic voltammetry and 1H NMR spectroscopy.

In this paper fabrication and characterization of Schottky gate planar field-effect transistors using poly(3-alkylthiophene) as an active semiconductor region are reported. This is the first time that planar MESFET transistors utilizing a polymer semiconductor have been fabricated and measured. Aluminum metal is used for the rectifying contact and two gold electrodes are constructed as source and drain. From the MESFET characteristic the channel carrier mobility is evaluated as 10 −5 cm 2 V −1 s −s , which is one order of magnitude larger than a MOSFET utilizing the same polymer.

The synthesis of three new bis(aryl)substituted tetrathiafulvalenes is presented together with their cyclovoltammetric behaviour.

The three step synthesis of 2,3,6,7-Tetrakis(methylthio)naphthalene (TMTN) 1 is described. The title donor gives a 1:1 salt with hexafluoroarsenate anion. The crystal structure consists of a dimerized donor stack, with alternate stacking. The conductivity is activated, room temperature conductivity; ≈10 −3 ·10 −4 Scm −1 . The susceptibility is quite low, χ (300K) = 7·10 −7 emu/mol, and the ESR linewidth is Δ B pp (300K)≈5 G.

The high yield, one-pot synthesis of three new donors for cation radical salts is described. These are 2,6-Dimethoxy-3,7-bis(methylthio)naphthalene 2a , 2,6-Dimethoxy-3,7-bis(methylseleno)naphthalene 2b , and 2,6-Dimethoxy-3,7-bis(methyltelluro)naphthalene 2c . They show a quasireversible halfwave potential with the values 1.05, 0.85, and 0.53 Volts respectively, the one for 2c being irreversible. 2a gives 3:2 salts when electrocrystallized in the presence of perchlorate and hexafluoroarsenate anions. The perchlorate salt is a semiconductor with a fairly high room temperature conductivity, 0.4–0.7 S/cm. This higher conductivity than the corresponding salt of 1a (2,7-Dimethoxy-3,6-bis(methylthio)-naphthalene) can be attributed to a high mobility, due to fewer stacking defects.

1,2-ethanedisulfenyl chloride 1 has been utilized as a electrophilic reagent for the preparation of dihydro-1,4-dithiino substituted aromatics. The title reagent reacts with activated aromatics to give several new heterocyclic systems in modest yields.

The synthesis of a series of new tetrathiafulvalenes (TTF:s), substituted with alkylthiol groups, is described. The synthetic procedure allows a range of substituents to be present.

Two new ethylenedithio substituted thiophenes (I; R = H, Br) have been synthesized. Starting from I (R = Br), oligomers II (n = 0, 1, 2) were synthesized. Their cyclic voltammetric behavior and ele ...

Results from cation radical salt synthesis with the donors DMOX 8 and ETOX 9 are presented together with the synthesis of a new unsymmetrical 1,4-dihydrooxathiino fused TTF; MDTOX 10.

Two series of chalcogen substituted thiophene monomers have been synthesised; 3-(4-alkylchalcogenophenyl)thiophenes 1a-c and 3-(4-alkylphenylchalcogeno)thiophenes 2a-d. Polymerisations of examples of these with iron(III)chloride gave regiorandom polymers. Light-emitting diodes with low efficiency could be fabricated from poly-1a and poly-1b.

Three isomeric tetramethyldithienothiophenes, 2,3,2′,3′-tetramethyldithieno(5,4-b:4′,5′-d)thiophene 1 , 2,3,2′,3′-tetramethyldithieno(4,5-b:5′,4′-d)thiophene 2 , and 2,5,2′,5′-tetramethyldithieno(3,4-b:3′,4′-d)thiophene 3 , have been synthesized. 2 and 3 show quasireversible cyclovoltammetric behaviour with halfwave potentials 0.92, and 0.95 V vs SCE respectively. Two new cation radical salts, ( 2 ) 2 PF 6 and ( 2 ) 2 PF 6 , have also been isolated.

The title compound (“Pooh”) has been synthesized from mercaptoethanol and methylbromoacetate in 6 steps with a total yield of 2–2.5 %. Upon electrocrystallization “Pooh” forms 2:1 salts with ClO 4 , PF 6 and BF 4 as anions. (Pooh) 2 ClO 4 has a powder conductivity of 5 S/cm and Pauli-paramagnetic behaviour down to 70K.

In this communication we present the electronic properties of (TMN)3(ClO4)2 and (TMN)3(AsF6)2. The properties were studied by ESR and conductivity measurements on single crystals and absorption measurements on powder. The cation stacks are trimerized causing the charge transport to be thermally activated. The spin properties are described by triplet spin excitations from a diamagnetic ground state. Differences in the electronic properties can be related to differences in the structures, caused by the different sizes of the anions.

The cation radical salts (crs) of tetramethoxydibenzofuran, (TMDBF)X, form non-stoichiometric salts with different anions (X = BF4−, ClO4−, AsF6− and PF6−). All investigated salts contained the solvent used in the electrocrystallization (CH2Cl2). The X-ray investigation showed that the crs were disordered. Conductivity measurements showed that the crs were thermally activated with Δ < 110 meV at high temperatures; at lower temperatures there are different deviations from this behaviour. All crs have σrt ∼ 10−2 (Ω cm)−1. The susceptibilities are large, χ ∼ 10−4 emu/mole, and barely temperature dependent between 300 and 50 K. Below 50 K, χ increases less than 1/T. These results are interpreted using a common model for σ and χ. Due to the quasi one-dimensionality of the crs, the disorder present causes all states to be localized. This leads to charge transport by phonon-assisted hopping between localized states near the Fermi level, and a paramagnetic susceptibility due to antiferromagnetic order in one dimension. Interacting chain segments exist with weak exchanges ϵJ at a random concentration among uniform nearest-neighbour exchanges J. The narrow e.s.r. lines (about 100 mG at room temperature) are caused by exchange narrowing, with an exchange frequency of about 1012 Hz.

The susceptibility of the title compound is large, χ (300 K) = 3.8 × 10 −4 emu/mol, and the temperature dependence of the susceptibility is explained by the random exchange Heisenberg antiferromagnetic chain model. The localization of the electrons in an antiferromagnetic order is proved by the angular dependence of the e.s.r. linewidth, which corresponds to dipole-dipole interaction. A comparison of the spin properties between the title compound and the non-deurated compound exhibits only minor differences.

The synthesis and cyclovoltammetric behaviour of nine donors based on dimethoxylated-dimethylchalcogenated naphthalenes is presented.