Showing papers on "Organic semiconductor published in 1992"

Electroluminescence and electrical transport in poly(3‐octylthiophene) diodes

Abstract: We report visible light emission from diodes made from poly(3‐octylthiophene). Use of a soluble derivative of polythiophene allows fabrication of the light emitting diodes by casting the polymer film from solution with no subsequent processing or heat treatment required. The devices emit dim red‐orange light with relatively low external quantum efficiencies, below 2.5×10−5 photons per electron at room temperature. Electrical characterization reveals diode behavior with rectification ratios greater than 102. The temperature dependence indicates that tunneling phenomena dominate the charge injection.

Characterization of the interaction between poly(pyrrole) films and methanol vapor

Abstract: A combination of mass, optical spectroscopy, and work function measurements has been used to study the interaction of methanol vapor with poly(pyrrole) thin films. The steady-state measurements carried out in this study open the way for qualitative and quantitative evaluation oF the charge-transfer and sorption interactions of organic vapors with the «network solids». It is shown that the chemical nature of the dopant anion incorporated in the poly(pyrrole) matrix strongly influences the reversible doping by the vapor

Gas-sensing properties of semiconducting films of crown-ether-substituted phthalocyanines

Abstract: The effects of nitrogen dioxide and ammonia on the semiconductivity properties of solution-deposited thin films of the tetra-substituted 15-crown-5, 18-crown-6 and 21-crown-7 metal-free and copper phthalocyamnes are reported. The 15-crown-5 films showed good reversible conductivity changes at room temperature in NO2 concentrations up to 5 ppm. The sensor characteristics worsen as the size of the crown-ether ring increases and this is consistent with the effect of greater separation of adjacent adsorbed species as molecular size increases. Lateral repulsions, which are believed to play a dominant role in controlling the response and reversal processes, are reduced by this increase. Treatment of the films with aqueous KCl solution led to dramatic changes in gas-sensing properties and, for the 15-crown-5 derivative, in film morphology. After KCl treatment the film conductivity decreased very rapidly and reversibly on exposure to NO2, even at room temperature, and the 15-crown-5 film changed from a polycrystalline needle structure to an extremely smooth structure. These effects are tentatively ascribed to pronounced changes in the molecular assembly induced by the interaction of the potassium ions with the crown-ether moieties, and to consequent changes in the porosity of the film to small gas molecules. Above 3 ppm NO2 the response begins to saturate, suggesting depletive chemisorption on an n-type material. However, similar responses are also observed for the electron-donor gas ammonia, indicating the presence of both donor and acceptor impurities in the materials. The gas-sensing properties of the KCl treated films at room temperature are the best of any organic semiconductor film yet reported.

Electrical properties of highly ordered and amorphous thin films of pentacene doped with iodine

Abstract: Studies on electrical properties of highly ordered and amorphous thin films of pentacene (PEN) doped with iodine have been made. Highly ordered film heavily doped with iodine (PEN1I2.2) showed electrical conductivity of 150 Ω−1 cm−1 with a hole mobility of 0.2 to 1 cm2 V−1 s−1 at room temperature. Metallic temperature dependence of the conductivity of the film from 240 to 4 K was observed as the first metallic transport phenomenon ever noted in an acenic compound. In contrast, amorphous film of PEN doped with iodine showed a conductivity of 10−3 Ω−1 cm−1 with an estimated hole mobility of 2×10−5 cm2 V−1 s−1 and semiconductive transport. These results revealed that the electrical properties of PEN thin films are strongly correlated with the degree of molecular orientation.

Carrier injection characteristics of the metal/organic junctions of organic thin‐film devices

Abstract: The junction characteristics of metal/organic thin film (M/Org) interfaces were investigated by measuring the displacement currents for the structure of M/Org/SiO2/Si devices. The observed currents were ascribed to the carriers injected from metal electrodes into organic films, which were markedly dependent both on metals and organic materials employed. The threshold bias for carrier injection was also found to be dependent on the metal work function. The results can thus provide some detailed information about the junction properties including the potential barriers formed at the M/Org interfaces.

Hall-effect observation in the new organic semiconductor bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole)(BTQBT)

Abstract: Single crystals of bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole)(BTQBT) were grown either by recrystallization from a nitrobenzene solution or by sublimation in nitrogen atmosphere The electrical resistivities were 1.2 × 103Ω cm and 2.7 × 105Ω cm at room temperature for a crystal grown by recrystallization and that obtained by sublimation, respectively. These values are remarkably low for a single-component organic crystal. In addition, the BTQBT crystals have a small anisotropy in resistivity (ρ⊥/ρ∥, ≈ 2), which is ascribed to strong intermolecular interactions inherent in the crystal structure. They show a Hall effect which is an unusual observation in organic semiconductors. The sign of carriers was determined to be positive and the Hall mobility was found to be ca. 4 cm2 s–1 V–1 at room temperature.

Observation and modeling of quasiepitaxial growth of a crystalline organic thin film

Abstract: We directly observe, using the scanning tunneling microscope, a two‐dimensional crystal of the organic compound 3, 4, 9, 10‐perylenetetracarboxylic dianhydride (PTCDA). The surface unit cell dimension is found to be 21.6±2.2 A by 15.2±1.6 A, or approximately 20% larger than the bulk unit cell. Furthermore, the organic lattice is oriented with respect to the graphite substrate even though the two lattices are incommensurate. These observations are consistent with reflection high energy electron diffraction measurements, and energy minimization calculations, assuming that the van der Waals bond is the predominant intermolecular force which determines the equilibrium crystal structure. The combination of measurement and theory provides the first step in developing tools for predicting the conditions which lead to quasiepitaxial growth of these technologically important van der Waals solids.

Instability in electrical performance of organic semiconductor devices

Abstract: A field effect transistor (FET) has been fabricated with the hexamer of thiophene (α-sexithienyl) in order to assess the performance of such electronic devices based on an organic material. Particular emphasis has been given to the determination of the origin of the instability in the electrical performance. From this study it is confirmed that charged species, possibly chemical impurities present in the processed material, can migrate through the film under an applied electric field, even at room temperature.

Evolution of quasi‐epitaxial growth of a crystalline organic semiconductor on graphite

Abstract: We have studied the evolution of the growth of a crystalline organic semiconductor thin film using reflection high energy electron diffraction (RHEED). Our results indicate that highly ordered crystalline films of an organic compound; namely 3, 4, 9, 10‐perylenetetracarboxylic dianhydride (PTCDA), can be grown on graphite by the ultrahigh vacuum process of organic molecular beam deposition even though the crystal structures of the two materials are highly mismatched. The RHEED patterns show the evolution of planar crystal growth from 2 monolayer (∼6 A) coverage until at least 50 A as the films are deposited onto substrates cooled to 100 K. At larger film thicknesses, somewhat nonplanar but still crystalline growth occurs. Furthermore, crystalline thin films were obtained independent of growth rate, which was as high as 3.0 A/s. To our knowledge, this is the first direct experimental evidence of the evolution of growth from monolayer to bulk film coverage into an ordered, quasi‐epitaxial structure.

Crystalline organic semiconductor optical directional couplers and switches using an index-matching layer

Abstract: A directional coupler using crystalline organic semiconductor waveguides grown by the vacuum process of organic molecular beam deposition is demonstrated An index-matching layer placed between two coupled waveguides separated by a 1 mu m gap greatly increases the coupling coefficient, significantly decreasing the coupling length and making the device very compact Switching of 106 mu m wavelength light from one guide to another in the coupler has been observed by pumping the surface of one guide in the coupling region with 0514 mu m >

Influence of the molecular structure on the refractive index of semiconducting di‐β‐alkylated sexithiophenes

Abstract: The optical absorption of thin solid films of dialkylated sexithiophene derivatives (2A6T) has been measured at incident energies below the fundamental absorption edge, where these semiconducting organic materials are transparent. The absorption spectra present interference patterns that have been used for determining their refractive index n. A value of 1.904 was measured on unsubstituted sexithiophene. Alkyl substitution leads to a decrease of n, which is more pronounced as the alkyl chain length increases. This behavior is attributed to the corresponding decrease of the density of the material. Our data are compared to other experimental determinations of the optical parameters of thiophene oligomers and polymers published to date.

Field-effect transistor and manufacture thereof

Abstract: PURPOSE: To improve a carrier mobility in a field-effect transistor using an organic semiconductor layer as a semiconductor layer. CONSTITUTION: A gate electrode 2 is formed on a glass substrate 1 and a silicon oxide film is formed thereon as an insulating film 3. Control of molecular weights is performed by an ultrafiltration or the like, a poly (3-ockyl thiophane) chloroform solution set several mean molecular weights at 50000 or more is spin-coated and a high-molecular organic semiconductor layer 6 is formed. Gold electrodes, which are used as source and drain electrodes 4 and 5, are formed thereon. A carrier mobility is 2.2×10 -5 cm - 2/V.sec. COPYRIGHT: (C)1994,JPO&Japio

Electronic Properties of Conjugated Polymers : Proceedings of an International Winter School, Kirchberg, Tirol, March 14-21, 1987

Abstract: I Conductivity.- Electronic Transport in Low-Conductivity Metals and Comparison with Highly Conducting Polymers.- Synthesis of New Conductive Electronic Polymers.- Long Mean Free Path Coherent Transport in Doped Polyacetylene.- Frequency- and Temperature-Dependent Dielectric Losses in Lightly Doped Conducting Polymers.- Variable-Range Hopping in Polymers Prepared from Iodo-(2-nitrophenyl)-acetylene.- Transport Studies on Polypyrrole Films Prepared from Aqueous TsONa Solutions of Different Concentrations.- II Defects and Conjugation Length.- Influence of the Conjugation Length of Polyacetylene Chains on the DC-Conductivity..- Conjugation Length and Localization in Conjugated Polymers.- Theoretical Investigations of Segmented Polyacetylene.- Analysis of the Raman Spectra of Modified trans-(CH)x.- Conformation of Conjugated Polymers and Their Relation to Electron Delocalisation.- Polyacetylene Segments in a Polyvinylidene-Chloride Matrix: Anisotropic Optical Properties.- III Electron Energy Loss, Optical and Raman Spectroscopy.- Electronic Structure of Conducting Polymers by Electron Energy-Loss Spectroscopy.- Electronic Structure of Undoped and Doped Polyphenylenevinylene..- Electronic Structure of Doped Highly Oriented Polyacetylene.- Polarization Dependence of Recombination Kinetics in Stretch-Oriented trans-Polyacetylene.- Photogeneration Mechanism and Mobility in Polydiacetylene.- Polarised Photoexcitation in Oriented Polyacetylene.- Radiative and Non-radiative Recombination Processes in Photoexcited Poly(p-phenylene vinylene).- Photoinduced Absorption in Poly(p-phenylene vinylene).- Spectroscopy of Photo-Induced Solitons in cis-rich and trans- Polyacetylene.- Photoinduced Infrared Absorption in Polydiacetylene.- Towards Solid State Investigations on Polyacetylene.- Raman Scattering of Highly Oriented Polyacetylene.- Experimental Raman Investigation of Oriented Undoped and Iodine Doped Polyacetylene.- Polarization Properties of the Raman Spectra in trans- and cis-Polyacetylene.- Interpretation of the Raman Spectra of n-doped trans-(CH)x Films..- IV Magnetic Resonance.- 10.1007/978-3-642-83284-0_28Pulsed ENDOR and TRIPLE Resonance on trans-Polyacetylene a 1a Durham Route.- ESR Study of Metallic Complexes of Alkali-Doped Polyacetylene.- In situ ESR Study During the Electrochemical Intercalation of Potassium in Polyacetylene.- 7Li NMR Study of the Electrochemical Doping of Poly(acetylene).- pz-Radical Electron Structure in Polydiacetylene (PDA) Molecules.- Triplet State ODMR of Polydiacetylene Crystals.- V Theory.- Electronic and Nonlinear Optical Properties of Conjugated Polymers: A Quantum Chemistry Approach.- On the Role of the Coulomb Interaction in Conjugated Polymer.- Lattice Relaxation Approach to Soliton and Polaron Dynamics in Conducting Polymers..- VI Polyaniline.- Photoelectrochemistry of Polyaniline.- Redox Mechanisms in Polyaniline Films.- In situ FTIR Spectroscopy of Polyaniline.- Spectroscopic Investigation of Polyaniline.- In situ Ellipsometry of Early Steps of Polyaniline Electrosynthesis.- Electronic Properties of Polyaniline.- On the Acidic Functions of Polyaniline.- Thermochromism and Acidochromism in Substituted Polyanilines.- Spectroscopic Studies of some Model Molecules for Polyaniline.- ESCA Studies of Polyaniline and Polypyrrole.- Mass Spectroscopy of Chemical Processes in Conducting Polymers: Polyaniline..- Synthesis and Properties of a Conducting Polymer Derived from Diphenylamine..- VII Polypyrrole, Polythiophene and Polyparaphenylene.- On Polaron and Bipolaron Formation in Conducting Polymers.- ESR of BF?4-Doped Poly(3-methylthiophene).- Influence of the Monomer Size on the Electronic Structure of Thiophene-Like Polymers.- Ion Implantation of Polythiophene.- Characterization of Polypyrrole-Polyvinyl Alcohol Composite Prepared by Chemical Oxidation of Pyrrole.- Electrochemistry of Polypyrrole-Ferrocyanide Films.- Synthesis and Physical Properties of 3,4-Disubstituted Polypyrroles..- A New Polyparaphenylene Thin Film Obtained by Electroreduction: Characterization and Electrochemical Studies.- VIII Special Materials.- Control of the State of Order in Poly(p-phenylene vinylene) and Its Effect on Iodine Doping.- Electronic Excitations in Polysilanes.- Doping Experiments with ?-(Pyrazine)phthalocyaninatoiron(II).- Optical and Electrical Properties of a New Conductive Polyheterocycle: Poly( 1,4-di(2-thienyl))benzene.- Preparation, Spectroscopic and Electrical Characterization of a New Polyheterocycle: Poly-benzo(l,2-6 4, 3-b)dithiophene.- Investigation of Undoped and Alkali-Metal Doped Poly(p-phenylene Selenide).- Structural Characterization of Polymers Prepared from Iodophenylacetylene by Heating at Different Temperatures.- Metallic Coordination Polymers Using CS2 as Starting Material.- (QP)4(SbF6)3: A Model Compound for Doped Polymers?.- IX Related Topics.- Supermolecular Structures Based on Langmuir-Blodgett Films.- Preparation and Structure of Langmuir-Blodgett Films of Polymers..- BEDT-TTF Radical Salts: Organic Metals and Superconductors.- Electrical Conducting Molecular Crystals in a Polymer Matrix.- X Applications.- Grafting, Ionomer Composites, and Auto-doping of Conductive Polymers..- On the Charge Storage Mechanism of Conducting Polymers.- Electrochemical Investigations and Neutron Activation Analysis of Polyacetylene.- Low Frequency Impedance Measurements on Polypyrrole.- Poly(alkyl thiophenes) and Poly(substituted heteroaromatic vinylenes): Versatile, Highly Conductive, Processible Polymers with Tunable Properties.- Electrical Conductivity in Heterogeneous Polymer Systems.- Organic and Polymeric Non-linear Optical Materials: Properties and Applications..- Preparation of Conducting Polymers by UHV-Compatible Methods..- Organic Semiconducting Polymers for New Electronic Devices.- Polymer-Based Conducting Material Used for Water Vapour Detection in Air.- A Novel Application of Conducting Polymers: Remotely Readable Indicator Devices..- Index of Contributors.

Organic Semiconductor Gas Sensors

Abstract: The electrical properties of semiconductors are drastically altered by the presence of small quantities of impurities. This phenomenon is well-known for impurities introduced into the bulk of semiconductors (doping) and has found wide application. Impurities present at the surface by adsorption of gases from the ambient can also considerably affect the semiconductivity. This is of growing technical interest as it may offer opportunities for the detection of gases.

Organic based thin film transistors

Abstract: The author discusses developments in high performance TFT's using organic semiconductors including new conjugated polymers and short conjugated oligomers. >

Studies of the Interactions between Organic Vapours and Organic Semiconductors. Applications to Chemical Sensing

Abstract: A combination of mass, optical spectroscopy and work function measurements has been used to study the interaction of organic vapours with conducting polymers. These steady-state measurements open the way for a qualitative and quantitative evaluation of the charge transfer and sorption interactions of organic vapours with these “network solids”.

Photoelectric properties in microscopic p‐n junctions of organic semiconductors

Abstract: Photodiodes containing microscopic p‐n junctions of organic dyes were fabricated using the Langmuir–Blodgett technique. Their action as p‐n junctions was confirmed by measurement of transient photoinduced voltage responses to impulsive laser light irradiation. The signal is characterized by a rapid rise followed by a slow decay, which are assignable to the photoinduced electron transfer from n‐type dye to p‐type dye and the reverse transfer through the junction, respectively. The decay process shows a long‐time tail and cannot be described by a single exponential function.

A.C. dielectric spectroscopy of oxonol dyes . A versatile probe for the examination of charge in organic semiconductors

Abstract: Low-frequency a.c. dielectric spectroscopy has been used to probe contact effects on, and the dielectric behaviour of, a series of structurally related organic dyes (hydroxypyridone trimethine oxonol salts) as compressed powders. The technique reveals contributions from dipolar relaxation, small-particle migration, and electronic conductivity depending on the nature of the counter cation. In general, whilst changing contacts to the samples modified the relaxation rate, neither the spectral form nor the magnitude of the a.c. response were affected.

Electron delocalization length in organic semiconductors and magnetic field effect

Abstract: New method is suggested and applied for an estimation of the delocalization length of charge carriers in photoconductive polymers based on the magnetic field effect (MFE) on the photoconductivity (PC). The method was applied to photoconductive polymers PTS, PPV, PPPV, DMOP-PPV and has permitted to estimate delocalization lengths as large as 60 A. It makes questionable the usage of Onsager's model of charge separation for conjugated polymers (CP).

Manufacture of active matrix substrate and liquid crystal display element using the same

Abstract: PURPOSE:To reduce the manufacturing cost by decreasing all forming processes of switching elements, electric conductors, and picture element electrodes which constitute the active matrix substrate. CONSTITUTION:A gate electrode 2 is formed by plating on a transparent substrate 1 whose surface is made of an insulator, an organic insulator such as polyimide is applied and set to form a gate insulating film 3, and an organic semiconductor is printed thereupon to form a semiconductor layer 4. A channel protection film 23 is formed at the part of a thin film transistor which becomes a channel and a source electrode 5 and a drain electrode 6 are formed by plating. Lastly, a picture element electrode 7 is formed by printing.

Solar cell having photo-conduction layer containing polysilane and organic semiconductor compound

Abstract: PURPOSE:To obtain solar cells having a high production efficiency and a low cost by providing a photo-conduction layer obtained by scattering an organic semiconductor compound and polysilane having alkyl group or/and aryl group for side chain and providing a metal electrode on or below the photo-conduction layer. CONSTITUTION:On a supporting body 101, sequentially formed are the first conduction layer 102, a photo-conduction layer 103 comprising a layer made by dispersing an organic semiconductor compound and polysilane having alkyl group and/or aryl group as side chain, the second conduction layer 104 forming a Schottky barrier with the photo-conduction layer and a reflection preventive layer 105. Also, lead wires 106 and 107 are provided. The Schottky barrier type solar cell having the configuration as stated above will not be deteriorated even after a long period of use, will stably provide a photo-electric conversion efficiency desired and can be efficiently produced with a good yield. By doing this, the solar cells can be produced efficiently with a good yield at a low cost.

Formation of pattern

Abstract: PURPOSE:To form various kinds of patterns without using any organic photoresist and organic solvent in the least by providing a photosensitive inorganic semiconductor on a semiconductor substrate and bringing the organic semiconductor into contact with an electrolyte so as to emit light having energy stronger than the band gap of the inorganic semiconductor. CONSTITUTION:After a gold layer 2 is formed on an insulating substrate 1 as a conductive metallic layer and a p-type silicon layer 3 is deposited on the layer 2, a tungsten oxide layer is formed as one of the n-type semiconductor layers 9 made of a photosensitive material. Then the substrate 1 is dipped in an electrolyte 11 and the semiconductor 9 is irradiated with ultraviolet rays by using a photomask 10. As a result, the part irradiated with the ultraviolet rays is removed and the p-type silicon film 3 is exposed. An n-type silicon layer 4 is formed to a desired shape by depositing the layer 4 and removing the remaining n-type photosensitive semiconductor layer 9. After another n-type photosensitive semiconductor layer 9 is vapor-deposited, a desired p-type silicon 5 pattern is formed in the same way. After forming the silicon 5 pattern, an n-type photosensitive semiconductor 9 is vapor-deposited and the semiconductor 9 is irradiated with ultraviolet rays so as to form a desired pattern. After forming the desired pattern, gold is vapor-deposited and tungsten oxide is again etched. Thus a field effect transistor is produced.

Thin Film Crystalline Organic Semiconductors: A New Class of Engineered Materials for Optoelectronics

Abstract: We have demonstrated that a class of stable aromatic compounds based on perviene and naphthalene can be deposited in extensive single crystalline thin films using the ultrahigh vacuum process of organic molecular beam deposition (OMBD). Furthermore, highly ordered ‘quasi-epitaxial’ structures consisting of alternating, ultra-thin (to 10A) layers of two or more crystalline organic compounds have also been grown using this novel process, thus opening the door to a wide range of artificially ‘engineered’ structures analogous to conventional semiconductor multiple quantum wells (MQWs). Unlike the case of inorganic semiconductors, however, organic materials bonded by the flexibly van der Waals forces are free of the need to choose layer compositions from materials whose crystal structures are matched. In this paper we summarize many of the unusual growth and materials characteristics of quasi-epitaxial organic thin films grown by OMBD.

Organic thin film element

Abstract: PURPOSE:To provide an organic thin film element which is of sandwich-type structure and takes advantage of an open-ended voltage (Voc) that is considered to be induced basing on an inner electric field without applying an outer bias voltage and whose principle of operation is basically different from that of a conventional sandwich-type organic thin film element composed of a back electrode, an organic semiconductor layer, and a front electrode CONSTITUTION:A sandwich-type organic thin film element of this design is composed of a back electrode 2, an organic semiconductor layer 3, and a front electrode 4, where the back electrode 2 is formed of metal larger than the organic semiconductor layer 3 in work function, the front electrode 4 is formed of metal whose work function is smaller than that of the organic semiconductor layer 3, and the organic semiconductor layer 3 is formed of lead phthalocyanine evaporation film, and therefore the degree of vacuum can be quantitatively detected by measuring an open-ended voltage

Photoconductive liquid crystal light valve

Abstract: PURPOSE:To form the organic semiconductor liquid crystal light valve having advantages, such as good yield, short film-forming time of the semiconductor layer, low cost, sufficient photosensitivity, high dark resistivity, short switching reaction time, and high contrast image storage, as compared with the case of using an amorphous silicon semiconductor. CONSTITUTION:As the photoconductive layer 3 of the liquid crystal light valve for storing optical information the organic compound semiconductor is used. This photoconductive layer 3 may be composed of a carrier generating layer containing dibromoanthanthrone and a carrier generating layer containing a hydrazone derivative material.

Gas‐Sensing Properties of Semiconducting Films of Crown‐Ether‐ Substituted Phthalocyanines.

Abstract: The effects of nitrogen dioxide and ammonia on the semiconductivity properties of solution-deposited thin films of the tetra-substituted 15-crown-5, 18-crown-6 and 21-crown-7 metal-free and copper phthalocyamnes are reported. The 15-crown-5 films showed good reversible conductivity changes at room temperature in NO2 concentrations up to 5 ppm. The sensor characteristics worsen as the size of the crown-ether ring increases and this is consistent with the effect of greater separation of adjacent adsorbed species as molecular size increases. Lateral repulsions, which are believed to play a dominant role in controlling the response and reversal processes, are reduced by this increase. Treatment of the films with aqueous KCl solution led to dramatic changes in gas-sensing properties and, for the 15-crown-5 derivative, in film morphology. After KCl treatment the film conductivity decreased very rapidly and reversibly on exposure to NO2, even at room temperature, and the 15-crown-5 film changed from a polycrystalline needle structure to an extremely smooth structure. These effects are tentatively ascribed to pronounced changes in the molecular assembly induced by the interaction of the potassium ions with the crown-ether moieties, and to consequent changes in the porosity of the film to small gas molecules. Above 3 ppm NO2 the response begins to saturate, suggesting depletive chemisorption on an n-type material. However, similar responses are also observed for the electron-donor gas ammonia, indicating the presence of both donor and acceptor impurities in the materials. The gas-sensing properties of the KCl treated films at room temperature are the best of any organic semiconductor film yet reported.

Hall‐Effect Observation in the New Organic Semiconductor Bis(1,2,5‐ thiadiazolo)‐p‐quinobis(1,3‐dithiole) (BTQBT).

Abstract: Single crystals of bis(1,2,5-thiadiazolo)-p-quinobis(1,3-dithiole)(BTQBT) were grown either by recrystallization from a nitrobenzene solution or by sublimation in nitrogen atmosphere The electrical resistivities were 1.2 × 103Ω cm and 2.7 × 105Ω cm at room temperature for a crystal grown by recrystallization and that obtained by sublimation, respectively. These values are remarkably low for a single-component organic crystal. In addition, the BTQBT crystals have a small anisotropy in resistivity (ρ⊥/ρ∥, ≈ 2), which is ascribed to strong intermolecular interactions inherent in the crystal structure. They show a Hall effect which is an unusual observation in organic semiconductors. The sign of carriers was determined to be positive and the Hall mobility was found to be ca. 4 cm2 s–1 V–1 at room temperature.