Showing papers on "Organic semiconductor published in 1986"
TL;DR: In this article, a vibrational analysis of the title compound and of its monomeric radical anion is reported, based on the Raman depolarization ratio measurements and on infrared data of solutions of both neutral and ionic species as well as on polarized infrared spectra of oriented crystals of the neutral molecule.
Abstract: A fundamental aspect in the study of the charge–transfer (CT) organic crystals with ionic or partially ionic ground states is the investigation of the spectroscopic effect of the electron–molecular vibration coupling. 7,7,8,8‐tetracyano‐2,3,5,6‐tetrafluoroquinodimethane (TCNQF4), an electron acceptor much stronger than TCNQ, is an outstanding component of many interesting CT systems. A thorough vibrational analysis of the title compound and of its monomeric radical anion is reported. The analysis is based on the Raman depolarization ratio measurements and on infrared data of solutions of both neutral and ionic species as well as on polarized infrared spectra of oriented crystals of the neutral molecule. The vibrational assignment, completed by a normal coordinate analysis (NCA), brings to the identification of the ionization frequency shifts and to the choice of the fundamentals (b1uν19 and b2uν33) whose frequencies are diagnostic of the degree of charge transfer for a TCNQF4 moiety partner of a CT system...
138 citations
TL;DR: In this article, the electrical conductivity of alkylthio-substituted tetrathiafulvalene (TTCn-TTF) single crystal has been measured in a vacuum of 10−4 Pa with the two probe method.
Abstract: The electrical conductivity of alkylthio-substituted tetrathiafulvalene (TTCn-TTF) single crystal has been measured in a vacuum of 10−4 Pa with the two probe method. The room temperature dark condu...
120 citations
TL;DR: In this paper, the currentvoltage and frequency-dependent admittancevoltage characteristics for OI diodes employing 3,4,9,10 perylenetetetracarboxylic dianhydride (PTCDA) and related compounds as the organic thin-film material were analyzed.
Abstract: Organic‐on‐inorganic (OI) contact barrier devices have been applied to the study of InP and In0.53Ga0.47As surfaces. The characteristics of these devices differ from OI diodes fabricated using Si or Ge substrates in that the contact barriers for InP‐based devices are relatively small (≤0.55 eV), and the diode characteristics are governed by a high density of states at the organic/inorganic interface. We present current‐voltage and frequency‐dependent admittance‐voltage characteristics for OI diodes employing 3,4,9,10 perylenetetracarboxylic dianhydride (PTCDA) and related compounds as the organic thin‐film material. Analysis of characteristics using a theory presented previously [S. R. Forrest and P. H. Schmidt, J. Appl. Phys. 59, 513 (1986)] indicates that the surface state density is (i) independent of the organic material employed, and (ii) sensitive to the exposure of the surface to chemical treatment prior to the organic thin‐film deposition. Using techniques derived previously, we determine the magn...
53 citations
TL;DR: In this article, the p-n heterojunction cells were successfully overcome and full visible solar spectrum coverage has been achieved and internal current generation quantum efficiencies of the order of 7% have been demonstrated.
47 citations
TL;DR: In this paper, the influence of surface charge transfer interactions on the magnitude, rate and reversibility of conductivity changes is reviewed and data presented on reversal rate as a function of temperature for NO2 on lead phthalocyanine films, yielding a desorption energy of 76 kJ mol−1.
Abstract: Experiments to evaluate several factors affecting the performance of organic semiconductors as gas sensors are reported. The influence of the strength of surface charge-transfer interactions on the magnitude, rate and reversibility of conductivity changes is reviewed and data presented on reversal rate as a function of temperature for NO2 on lead phthalocyanine films, yielding a desorption energy of 76 kJ mol−1. For copper phthalocyanine, surface heterogeneity prevents analysis of desorption rates in terms of a single desorption energy. Effects of the physical form of organic semiconductor surfaces on their gas sensing properties are reviewed and data presented showing these properties independent of film thickness for lead phthalocyanine on rough substrates. Studies of the effect of humidity on the response of lead phthalocyanine films to No2 are reported. At 12% relative humidity the conductivity increase is smaller than in dry conditions and proportional to NO2 concentration up to 0.1 ppm, sat...
29 citations
TL;DR: In this paper, an in situ study of the absorption spectra of poly(p-phenylene) films during the electrochemical doping with AsF 6 has been carried out.
Abstract: Poly( p -phenylene) films with a conductivity of ca . 100 S/cm are synthesized by a new method of electrical oxidation of benzene using the composite electrolytes of CuCl 2 /LiAsF 6 . An in situ study of the absorption spectra of the poly( p -phenylene) films during the electrochemical doping with AsF 6 has been carried out. From the absorption spectrum of undoped state, we find a strong absorption peak at ca . 3.4 eV which is associated with the transition from ground-state to excited-state. The remarkable changes of the absorption spectra below the photon energy of 3.0 eV are observed, which are related to the polaron and/or bipolaron states of this polymer. The electrochemical n -type doping is also demonstrated.
27 citations
TL;DR: Tetrakis(alkylthio)tetrathiafulvalenes constitute a new class of organic semiconductors offering unusually high conductivities; ultraviolet photoelectron spectroscopic experiments have been performed to investigate the valence electronic structures of these molecular solids as discussed by the authors.
Abstract: Tetrakis(alkylthio)tetrathiafulvalenes constitute a new class of organic semiconductors offering unusually high conductivities; ultraviolet photoelectron spectroscopic experiments have been performed to investigate the valence electronic structures of these molecular solids. The results have been analysed with help from extended-Huckel molecular-orbital calculations. In this series of compounds the central tetrathiotetrathiafulvalene portion is non-planar, but the degree of departure from planarity has little effect on the electronic structure. On the other hand, members of the series with many (≳8) carbon atoms in each alkyl chain possess extraordinarily low photoionisation thresholds (4.65 eV at minimum). For such solids large polarisation energies have been deduced, implying a relatively strong intermolecular interaction. Organic semiconductors in which, between adjacent molecules, the close packing of side chains enhances the interaction between the conjugated part of the molecule, are candidates for which high conductivity is desired.
22 citations
TL;DR: In this article, thin organic polymer films were prepared by plasma polymerization in the heated system and the electrical conductivities ranged from 10−6 to 10−7 S cm−1 and the Al/Polymer/Au cells with polymers produced from fumaronitrile and p-aminobenzonitrile.
Abstract: Thin organic polymer films were prepared by plasma polymerization in the heated system. The films obtained were very smooth and free of pinholes. The electrical conductivities ranged from 10−6 to 10−7 S cm−1 and the Al/Polymer/Au cells with polymers produced from fumaronitrile and p-aminobenzonitrile showed rectifying effect. Both IR observations and electrical measurements confirmed that the conjugated double bonds formed by plasma polymerization in the heated system were responsible for high electrical conductivity. The plot of logσ vs. 1/T gave straight line and 0.29 eV of the activation energy was determined for fumaronitrile polymer.
17 citations
TL;DR: In this paper, a process of molecular tuning of the physicochemical properties of organic semiconductors is described, with special reference being made to natural tetrapyrrole pigments, in the form of thin films, with emphasis being placed upon relative performance characteristics.
Abstract: A process of molecular tuning of the physicochemical properties of organic semiconductors is described, with special reference being made to natural tetrapyrrole pigments. The use of such organic semiconductors, in the form of thin films, is covered, with emphasis being placed upon relative performance characteristics. The view is expressed that chemical discrimination is possible.
13 citations
TL;DR: In this article, the application of copper phthalocyanine (CuPc) films to the detection of air-borne NH3 was investigated and a linear relation between minimum current intensity and partial pressure (concentration) of NH3 in the gas sample was obtained.
Abstract: The objective was to investigate the application of copper phthalocyanine (CuPc) films to the detection of air-borne NH3. The phenomenon of gas adsorption on the available surface area of an organic semiconductor was studied. Repeatable results can be obtained relatively quickly provided that a certain state of the semiconductor (which may be adopted as a reference system) will be re-established prior to each measurement of air-borne NH3. The development of an appropriate method for the regeneration of the CuPc film following completion of the detection procedure is described. A linear relation between minimum current intensity and partial pressure (concentration) of NH3 in the gas sample is obtained. The method proposed in this study for the measurement of atmospheric NH3 has analytical potential.
6 citations
Patent•
01 Jul 1986
TL;DR: In this paper, a wiring layer 7 made of a deposited film of phthalocyanines, such as nickel phothalocyanine is formed on a substrate 3b using alkali halide (KCl, KBr or NaCl) or graphite single crystal as a substrate.
Abstract: PURPOSE:To clearly and effectively achieve ON/OFF operation of a phthalocyanine film by using a highly clean crystal surface of alkali halide or graphite single crystal as a substrate. CONSTITUTION:A wiring layer 7 made of a deposited film of phthalocyanines, such as nickel phothalocyanine is formed on a substrate 3b. The substrate 3b uses alkali halide (KCl, KBr or NaCl) or graphite single crystal. The highly clean crystal surface of the single crystal can grow a crystal having much less defects, such as phthalocyanine. In the writing operation of a memory, a writing voltage of a certain value or higher is applied to specific lower aud upper electrodes 4b, 6b of matrix-like upper and lower electrodes 4b, 6b. In the reading operation of the memory, when a reading voltage of a certain value or lower is applied between specific lower and upper electrodes 4b and 6b and a current amount is read, whether the corresponding specific memory position is ON or OFF can be determined.
Patent•
10 Jan 1986
TL;DR: In this paper, it is shown that it is possible to polymerize a specified carbazole compound and deposit it on the positive electrode of a positive electrode in a nonaqueous organic solvent (e.g., propylene carbonate).
Abstract: PURPOSE:To produce the titled polymer which is moldable, excellent in oxidation stability and useful as an organic semiconductor material, by electrochemically polymerizing a specified carbazole compound CONSTITUTION:0001-10mol/l of a carbazole compound of the formula (wherein R is H, or a 10C or lower alkyl) and 0001-10mol/l of a supporting electrolyte (eg, LiPF6) are dissolved in a nonaqueous organic solvent (eg, propylene carbonate) Gold or platinum positive and negative electrodes are inserted into the solution, a potential is applied to this solution to polymerize the carbazole compound and deposit it on the positive electrode EFFECT:It is possible to produce in one step an electroconductive polymer (electric conductivity of 10 -10 OMEGA cm ) doped with 3mol or below of the anions of the supporting electrolyte per mol of the repeating units of the polymer
TL;DR: In this paper, the effects of iodine and xenon bombardment on organic semiconductors are investigated and a poly-N-vinylearbazole thin film is used for the ion implantation at energies in the range 30 to 80 keV.
Abstract: Effects of iodine and xenon bombardment on organic semiconductors are investigated. A poly-N-vinylearbazole thin film is used for the ion implantation at energies in the range 30 to 80 keV. The implantation profiles are measured by secondary ion mass spectrometry (SIMS). Changes in the light absorption due to formation of charge transfer (CT) complexes are measured.
[Russian Text Ignored].
TL;DR: In this paper, a new xerographic photoreceptor was formulated using a 1:4 mixture of copper phthalocyanine (CuPc) semiconductor powder and acrylate resin.
Abstract: A new xerographic photoreceptor was formulated using a 1:4 mixture (by weight) of copper phthalocyanine (CuPc) semiconductor powder and acrylate resin. Electrophotographic measurements on these films show that the photosensitivity, charge acceptance, light absorbance and dark decay could be optimised for xerographic applications when the annealing temperature was around 60°C and the film thickness was about 10 ?m.
TL;DR: In this article, the electron bombardment technique was used for the study of electrical transport properties in organic semiconductors and the lifetime of minority charge carriers in silicon solar cells was determined from the decay of the concentration of excess minority carriers.
Abstract: This paper describes in some detail the electron bombardment technique used for the study of electrical transport properties in organic semiconductors. A platelet specimen is fitted with electrodes on opposite sides and charge carriers are generated near the top electrode by a short bombarding pulse. Both light and electron pulses have been used for irradiating the crystal specimen and the particular advantages of electron beam excitation are discussed. A steady or pulsed applied field draws one type of carriers across the specimen and the transit time ‘T’ is determined by charge integration. This leads directly to the drift mobility. However, in the case ofp-n junction solar cells, the samples were bombarded with electron beam under reverse-biased conditions and the lifetime of minority charge carriers was determined from the decay of the concentration of excess minority charge carriers. Lifetime of minority charge carriers in silicon solar cells was found to be ∼25 μs, whereas in silicon specimens the lifetime of charge carriers was ∼8 μs. Measurement of carrier lifetimes, drift mobilities and carrier yields in organic semiconductors with the electron bombardment technique provides valuable information regarding the generation and recombination mechanisms, and the evaluation of the perfection of organic semiconductors which are to be used later for the fabrication of a variety of devices. Details of a space charge avoidance technique are given.
Book•
01 Jan 1986