Showing papers on "Organic semiconductor published in 1989"
TL;DR: In this paper, a metal-insulator-semiconductor field effect transistors (MISFET) with vacuum evaporated α-conjugated sexithienyl (α-6T) was fabricated and characterized.
467 citations
TL;DR: A series of α-conjugated thiophene oligomers α-nT (n = 4, 5, 6, 8) were synthesized and vacuum evaporated as thin films on various substrates in order to characterize their structural and electronic properties.
108 citations
TL;DR: In this paper, the influence of thermal treatment and gas exposure history on the kinetics of electrical conductivity changes occurring in sublimed films of lead phthalocyanine, chloroal aluminium phTHC, fluoroal aluminium PHTHC and its copper complex on exposure to sub-parts per million (ppm) concentrations of nitrogen dioxide (NO 2 ) in air have been studied.
107 citations
TL;DR: In this article, the authors studied the changes in the absorption, fluorescence emission, and fluorescence excitation spectra as the film order is increased from amorphous to crystalline.
Abstract: Zinc octakis(P-octoxyethyl)porphyrin, a new, liquid crystalline organic semiconductor, forms more highly ordered thin films than its non liquid crystalline analogue zinc octaethylporphyrin. Films of these two porphyrins are employed to study the changes in the absorption, fluorescence emission, and fluorescence excitation spectra as the film order is increased from amorphous to crystalline. The blue-shift of the B band and the red-shift of the Q bands in the absorption spectra are described, for all but the most highly ordered films, in terms of the molecular exciton model. The quantum yield for fluorescence increases with increasing order and, in the most crystalline samples, becomes strongly wavelength-dependent, decreasing for shorter excitation wavelengths. This is evidence for possible ring-to-ring charge-transfer (RRCT) state formation in competition with internal conversion. Emission, excitation, and absorption spectra in the solid, liquid crystalline, and liquid phases show that the observed spectral shifts are a function of the organization, not merely the proximity, of the neighboring chromophores.
86 citations
TL;DR: In this paper, a brief overview is given on literature dealing with purification, purity assessment, and crystal growth methods which are applicable to organic photoconductors and semiconductors under the aspect of the required high purity.
Abstract: First, a brief overview is given on literature dealing with purification, purity assessment, and crystal growth methods which are applicable to organic photoconductors and semiconductors under the aspect of the required high purity. Then some recent examples are presented of purification, material handling and crystal growth of some selected compounds (perylene, naphthalene, phenanthrene, TTF:chloranil and bipyridylammonium: (TCNQ)2). Progress is reflected in greatly improved electrical properties of these materials which allowed detection of entirely new features, such as enhanced charge carrier scattering at phase transitions and non-Ohmic transport. Finally, some advanced crystal growth techniques are presented: Czochralski growth of organic molecular crystals under high purity conditions, flux growth of donor:acceptor crystals from a melt solution in one of the two components, oriented epitaxial growth “organic on organic” and epitaxial growth of organic materials on inorganic substrates.
42 citations
TL;DR: In this article, high-efficiency high-bandwidth organic-on-inorganic (OI) semiconductor heterojunction photodetectors are discussed, which consist of a thin layer of the organic semiconductor perylenetetetracarboxylic dianhydride (PTCDA) in contact with an inorganic semiconductor (Si) substrate.
Abstract: High-efficiency high-bandwidth organic-on-inorganic (OI) semiconductor heterojunction photodetectors are discussed. The devices consist of a thin layer of the organic semiconductor perylenetetracarboxylic dianhydride (PTCDA) in contact with an inorganic semiconductor (Si) substrate. Indium tin oxide (ITO) is used as a transparent ohmic contact to the organic film. The external quantum efficiency of the detector was 85%, giving an internal quantum efficiency approaching 100%. The response time to fast optical pulses was 5 ns. Response times of OI detectors can be further reduced to about 100 ps by optimization of device parameters. >
38 citations
TL;DR: Oligomers of thiophene α-5T and α-6T were synthesized and vacuum evaporated as thin solid films onto platinized glass slides They all behave as p-type semiconductors, and good rectifying barriers were obtained at α-nT/Ag junctions as discussed by the authors.
32 citations
TL;DR: In this article, Goldmann and Kalandyk separated photoconduction from photoelectric emission, observing it in anthracene under U.V. irradiation, and also deduced the formula linking specific conductivity a with absolute temperature T, [sgrave] = [ sgrave]0,exp(-Eact/kT).
Abstract: The earliest studies concerned photoelectric emission of negative charges from dyestuff solutions,1,2 and anthracene layers.3 The negative charges were identified as electrons,4 then in 1911 Goldmann and Kalandyk5 separated photoconduction from photoelectric emission, observing it in anthracene under U.V. irradiation, while Pauli6 and Volmer7 studied photoconduction in anthracene in the visible. Petrikaln8 discussed gas effects on visible light photoconduction in dyestuffs, Koenigsberg and Schilling9 studied dark conduction in anthracene, naphthalene and alizarine and also deduced the formula linking specific conductivity a with absolute temperature T, [sgrave] = [sgrave]0,exp(-Eact/kT). Further dark conduction studies were carried out by Rabinowitsch.
27 citations
TL;DR: In this paper, a novel class of optoelectronic devices utilizing thin films of stable crystalline organic semiconductors layered onto inorganic semiconductor substrates is described. And the electrical properties of these devices are determined by the energy barrier at the heterojunction contact between the organic and inorganic materials, and in many ways are similar to those of ideal diffused-junction inorganic devices.
Abstract: A novel class of optoelectronic devices utilizing thin films of stable crystalline organic semiconductors layered onto inorganic semiconductor substrates is described. The electrical properties of these devices are determined by the energy barrier at the heterojunction contact between the organic and inorganic materials, and in many ways are similar to those of ideal diffused-junction inorganic semiconductor devices. The organic materials can be layered onto semiconductor substrates without inducing large strains in either material, hence allowing a wide range of material combinations with a similarly broad range of optoelectronic functions to be realized. As examples, high-bandwidth photodetectors and field-effect transistors made using organic/inorganic semiconductor heterojunctions are discussed. Modification of the optical and electronic properties of the organic films by irradiation with energetic electron and ion beams is considered. >
26 citations
TL;DR: In this paper, the deposition and characterization of Langmuir-blodgett films containing the organic semiconductor perylene are described, using a number of techniques, including absorption and fluorescence spectroscopy, surface plasmon resonance and ellipsometry.
18 citations
TL;DR: In this article, the ionization energy and carrier mobility measurements for the purpose of elucidating the conduction mechanism were performed for a series of single component organic semiconductors called molecular fasteners.
Abstract: The two major categories of organic solids are known to offer the present of good electrical conduction. The first group consists of charge-transfer complexes. Conductivity measurements on a large number of the charge-transfer complexes have been carried out. Among them, organic conductors (synthetic metals) and also organic superconductors have been discovered. The other group comprises single component materials; typical examples are polycyclic aromatic compounds and phthalocyanines. Their conductivities, generally speaking, are not as good as those of the charge transfer kind. We recently discovered a series of single component organic semiconductors having fairly good conductivity, which we called molecular fasteners. We also present, in this article, the experimental work on the ionization energy and carrier mobility measurements for the purpose of elucidating the conduction mechanism.
Patent•
30 Oct 1989TL;DR: In this paper, a phthalocyanine compound having amino groups is mixed with stearic acid to form a bonded substance capable of being dissolved in an organic solvent, and an organic solution is made by dissolving this bonded substance in the organic solvent.
Abstract: A method for manufacturing an organic semiconductor thin film (24) having an improved characteristic as a semiconductor is provided. A phthalocyanine compound having amino groups is mixed with stearic acid to form a bonded substance capable of being dissolved in an organic solvent. Then, an organic solution is made by dissolving this bonded substance in the organic solvent. By developing this organic solution on a water (20) surface, the thin layer (23) of this bonded substance is formed on the water (20) surface. Thereafter, this thin layer is moved onto a substrate (30) and accumulated to be deposited on the substrate (30). Next, the stearic acid is volatilized and removed from the above described thin film (23) deposited on the substrate (30) by baking the whole substrate. The thus structured organic semiconductor thin film (24) is used as a semiconductor material such as a photoelectric transfer device, a gas sensor, a transistor and the like.
TL;DR: In this paper, the first organic polymer semiconductor superlattices designed as periodic block conjugated copolymers, (−AxBy−)m, were synthesized by a two-step strategy that ensure strict control of sequence, block length and periodicity.
Abstract: We describe the synthesis and study of the first organic polymer semiconductor superlattices designed as periodic block conjugated copolymers, (−AxBy−)m. The observed variation of electronic spectra and wavelength of the lowest energy absorption maxima with block length y are interpreted in terms of quantum confinement size effects predicted for semiconductor superlattices. The periodic block conjugated copolymers were synthesized by a two-step strategy that ensure strict control of sequence, block length and periodicity. It is suggested that organic semiconductor superlattices provide a rational and systematic approach to the molecular engineering of electronic, optical, nonlinear optical, and electro–optical properties in polymeric materials and hold promise for molecular electronics and molecular photonics.
TL;DR: In this article, an introductory review on synthesis and properties of polyacetylene, a typical semiconducting and conducting organic polymer, is presented, along with an appropriate chemical and/or electrochemical doping with electron accepting or electron donating reagents, spanning the range of insulators and metals.
Abstract: This paper presents an introductory review on synthesis and properties of polyacetylene, a typical semiconducting and conducting organic polymer. Electrical conductivity of polyacetylene can be tailored by an appropriate chemical and/or electrochemical doping with electron accepting or electron donating reagents, spanning the range of insulators (10−12 S/cm) and metals (105 S/cm).
TL;DR: In Japan, the initiation of the studies of organic semiconductors was the work on carbons materials such as graphite and carbon black as discussed by the authors, and the work was carried out in the early 1970s.
Abstract: In Japan, the initiation of the studies of organic semiconductors was the work on carbons materials such as graphite and carbon black.
TL;DR: In this paper, the activation energies of the dimerized compounds with one radical electron per dimer are derived and a comparison of the available experimental data with those calculated from the hopping model is presented.
TL;DR: In this paper, the free-carrier concentration in n and p-type Hg1−yCdyTe layers was obtained and the valence-band discontinuity energy (ΔEv ) equal to (110±20) meV was obtained.
Abstract: Capacitance‐voltage data are utilized to obtain the free‐carrier concentration in n‐ and p‐type Hg1−yCdyTe layers, and to measure the valence‐band discontinuity energy of a p‐type Hg0.7Cd0.3Te/Cd(4% Zn)Te isotype heterojunction. To facilitate measurement, rectifying contact was made to the Hg1−yCdyTe layers using one of two organic materials—metal‐free phthalocyanine and copper phthalocyanine. Contrary to previous results with this heterojunction system, we find that holes are accumulated near the Cd(4% Zn)Te side (rather than Hg1−yCdyTe side). We obtain a valence band discontinuity energy (ΔEv ) equal to (110±20) meV, and a fixed interface charge density of σ=−(5.9±0.3)×1010 cm−2.
TL;DR: A review of the contribution of Canadian scientist to the field of organic semiconductors can be found in this paper, where the authors discuss semiconducting properties of organic materials like electrical conductivity, carrier transport, and photoconductivity.
Abstract: In Canada the systematic investigation of organic semiconductors started in the mid 1950's. This review of the contribution of Canadian scientist to the field of organic semiconductors will be limited to discussing semiconducting properties of organic materials like electrical conductivity, carrier transport, and photoconductivity. Substantial spectroscopic work on organic semiconductors has been performed including optical spectroscopy (absorption, reflectance, luminescence, Raman), NMR, and ESR. Here spectroscopic measurements will only be covered inasmuch as they illuminate semiconductive material properties. Significant work has also been reported on organic xerographic photoreceptors and photovoltaic solar cells. This work will be covered to the extent of contributing to our understanding of electrical properties and material parameters in organic semiconductors. In recent years electrical properties of polymers have also attracted significant attention. These developments, however, are outs...
TL;DR: In this article, the reflectance of the organic semiconductor 2,7-dimethoxy-3,6-bis(methylthio)naphthalene-perchlorate has been measured in the VIS and near-IR regime.
TL;DR: In this article, the junction characteristics of organic semiconductor-metal and organic inorganic semiconductor devices were studied and the effect of an electro-polymerization condition, film thickness, and doping density in junction characteristics was investigated.
TL;DR: The publication of the book by Mott and Gurney as discussed by the authors explaining the electronic properties of ionic crystals in quantum mechanical terms played a significant role in establishing the latter part of 1940 as the beginning of modern studies of organic semiconductors.
Abstract: Although isolated studies of organic semiconductors and photoconductors were made starting from the beginning of this century, there was no comprehensive theory to rationalize the results. The publication of the book by Mott and Gurney1 explaining the electronic properties of ionic crystals in quantum mechanical terms played a significant role in establishing the latter part of 1940 as the beginning of modern studies of organic semiconductors.
Book•
01 Jan 1989
Patent•
21 Nov 1989
TL;DR: In this article, the electron donative organic compound is fabricated on an electrode substrate or a substrate by application process or vacuum depositing process, and then an organic semiconductor film or an organic conductor film is fabricated by dipping the substrate or the substrate formed with the electron-donative organic film, together with the opposing electrode if necessary, into an electrolyte solution which does not dissolve the electrondonative compound, and applying a voltage between both electrodes to carry out the electrolytic oxidation reaction.
Abstract: PURPOSE:To efficiently manufacturing an organic semiconductor film or an organic conductor film by including a process for fabricating a film of an electron donative organic compound on an electrode substrate or a substrate and a process for electrolytically oxidizing the film. CONSTITUTION:A film of an electron donative organic compound is fabricated beforehand on an electrode substrate or a substrate by application process or vacuum depositing process. Then, an organic semiconductor film or an organic conductor film is fabricated by dipping the electrode substrate or the substrate formed with the electron donative organic film, together with the opposing electrode if necessary, into an electrolyte solution which does not dissolve the electron donative organic compound, and applying a voltage between both electrodes to carry out the electrolytic oxidation reaction. As the electron donative organic compound, fulvalenes having chalcogen atom in a molecule are used.
TL;DR: In this article, the acceptors for charge transfer complexes in the first decade of the organic semiconductor research were discussed, and properties and characterization of the following combinations with organic donor compounds were described in detail: perylene-bromine, peryleneiodine, phenothiazine-iodine and aromatic diamine-p-chloranil and -p-bromanil.
Abstract: This review will deal mainly with the acceptors frequently employed for charge-transfer complexes in the first decade of the organic semiconductor research. Particularly, the properties and characterization of the following combinations with organic donor compounds will be described in detail: perylene-bromine, perylene-iodine, phenothiazine-iodine, and aromatic diamine-p-chloranil and -p-bromanil. Many of these complexes have been known long before their recognition as organic semiconductors. The author attempted to present how their close examinations have provided useful features to further studies.
TL;DR: The photo-induced area-selective reactions occurring on semiconductor electrodes can be utilized as a new method of the micro patterning of polymer materials as mentioned in this paper, which can be applied not only to an imaging system but also to an integrated electronic device.
Abstract: Publisher Summary When a partial area of a semiconductor electrode surface that is in contact with an electrolyte solution is irradiated with light, an electrochemical reaction takes place selectively on the irradiated surface area. These kinds of reactions are named as “area-selective reactions.” The photo-induced area-selective reactions occurring on semiconductor electrodes can be utilized as a new method of the micro patterning of polymer materials. The chapter shows that both the conductive and the insulating polymers are deposited area-selectively on the electrodes employed, giving examples of photodeposition of polypyrrole and photo-assisted electrodeposition coating on TiO 2 . The organic materials have a wide variety of compounds and thus the photo-induced micro patterning with organic polymers can be applied not only to an imaging system but also to an integrated electronic device. In addition, when an organic semiconductor is employed as an electrode a total organic intelligent device can be realized combining the conductive and insulating polymers.