JP2006108220A - Organic thin-film transistor, material thereof, field effect transistor, and switching device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic thin-film transistor which is superior in characteristic as a transistor and whose deterioration with time lapse is suppressed, and to provide an organic thin-film transistor using the same, a field effect transistor, and a switching device. <P>SOLUTION: The organic thin-film transistor material contains compound represented by a general formula (1). In the formula R<SP>1</SP>-(Z)<SB>n</SB>-R<SP>2</SP>, R<SP>1</SP>is an aromatic hydrocarbon group or an aromatic heterocyclic group, and R<SP>2</SP>is a monovalent substituent. R<SP>1</SP>does not become the same as R<SP>2</SP>. Z stands for a partial structure having a conjugated system region, and n is an integer of 1 to 5. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic thin film transistor material, an organic thin film transistor, a field effect transistor, and a switching element.

  With the widespread use of information terminals, there is an increasing need for flat panel displays as computer displays. In addition, with the progress of computerization, information that has been provided on paper media in the past has become more and more electronically provided. As a mobile display medium that is thin, light, and easy to carry, electronic paper or There is a growing need for digital paper.

  In general, in a flat display device, a display medium is formed using an element utilizing liquid crystal, organic EL, electrophoresis, or the like. In such display media, a technique using an active drive element (TFT element) as an image drive element has become mainstream in order to ensure uniformity of screen brightness, screen rewrite speed, and the like. For example, in a normal computer display, these TFT elements are formed on a glass substrate, and liquid crystal, organic EL elements, etc. are sealed.

  Here, semiconductors such as a-Si (amorphous silicon) and p-Si (polysilicon) can be mainly used for the TFT element, and these Si semiconductors (and metal films as necessary) are formed into a multilayer structure. The TFT element is manufactured by sequentially forming the drain and gate electrodes on the substrate. The manufacture of such TFT elements usually requires sputtering or other vacuum manufacturing processes.

  However, in the manufacture of such a TFT element, the vacuum system manufacturing process including the vacuum chamber must be repeated many times to form each layer, and the apparatus cost and running cost have become enormous. . For example, in a TFT element, it is usually necessary to repeat processes such as vacuum deposition, dope, photolithography, development, etc. many times to form each layer, and the element is formed on a substrate through tens of steps. Yes. As for the semiconductor portion that is the key to the switching operation, a plurality of types of semiconductor layers such as p-type and n-type are stacked. In such a conventional manufacturing method using a Si semiconductor, it is not easy to change the equipment, for example, a design change of a manufacturing apparatus such as a vacuum chamber is required in response to the need for a large display screen.

  In addition, since the conventional TFT element using the Si material includes a process at a high temperature, the substrate material must be a material that can withstand the process temperature.

  Therefore, in practice, glass must be used, and when the above-described thin display such as electronic paper or digital paper is configured using such a conventionally known TFT element, the display is heavy and flexible. Products that may break due to chipping or dropping impact. These characteristics resulting from the formation of TFT elements on a glass substrate are undesirable in satisfying the need for an easy-to-carry-type thin display accompanying the progress of computerization.

  On the other hand, in recent years, organic semiconductor materials have been energetically studied as organic compounds having high charge transport properties. In addition to charge transport materials for organic EL devices, these compounds are expected to be applied to organic laser oscillation devices (for example, Non-Patent Document 1) and organic thin film transistors reported in many papers. (For example, nonpatent literature 2.).

  If these organic semiconductor devices can be realized, there is a possibility of obtaining a semiconductor that can be made into a solution by simplifying the manufacturing process by vacuum or low-pressure deposition at a relatively low temperature and further improving the molecular structure appropriately. It is conceivable that the organic semiconductor solution is made into an ink and manufactured by a printing method including an ink jet method. Manufacturing by these low-temperature processes has been considered impossible for conventional Si-based semiconductor materials, but there is a possibility for devices using organic semiconductors, so the above-mentioned restrictions on substrate heat resistance are relaxed. For example, a TFT element may be formed on the transparent resin substrate. If a TFT element is formed on a transparent resin substrate and the display material can be driven by the TFT element, the display is lighter and more flexible than conventional ones, and will not crack even if dropped (or very difficult to break) It could be a display.

  However, organic semiconductors for realizing such TFT elements have been studied so far as acenes such as pentacene and tetracene (for example, see Patent Document 1), phthalocyanines including lead phthalocyanine, perylene and its tetra. Low molecular weight compounds such as carboxylic acid derivatives (for example, see Patent Document 2), aromatic oligomers typically represented by thiophene hexamers called α-thienyl or sexithiophene (for example, see Patent Document 3), naphthalene, Compounds in which a 5-membered heteroaromatic ring is condensed symmetrically on anthracene (for example, see Patent Document 4), mono, oligo and polydithienopyridines (for example, see Patent Document 5), polythiophene, polythienylene vinylene, poly -Conjugated polymers such as p-phenylene vinylene Etc. limited number of compounds (e.g., see Non-Patent Documents 1 to 3.) Have only in the development of the semiconductor composition using the novel charge-transporting material showing high carrier mobility has been awaited.

  Although a pentacene derivative-containing layer that has been reported to have good TFT characteristics as a conventionally known organic semiconductor material is not formed through a vapor deposition step, a large cost advantage in manufacturing can be expected if solution coating such as an inkjet method can be applied. However, it has been pointed out that the coating solution has insufficient stability, such as insufficient solubility in various organic solvents, and crystallization and precipitation are likely to occur after solution preparation. In view of this, for the purpose of improving solubility and coating solution stability, a technique relating to an organic TFT material using a pentacene derivative having a substituent introduced therein (for example, see Patent Documents 9 and 10) is disclosed. However, it is difficult to obtain sufficient solubility by introducing an alkyl group or the like, operability such as temperature control at the time of coating is difficult, and it is difficult to produce a uniform coating film.

In addition, in Japanese Patent Application Laid-Open No. 2003-292588, US Patent Application Publication Nos. 2003/136958, 2003/160230, and 2003/164495, “a polymer TFT in an integrated circuit logic element for microelectronics” is disclosed. However, most of the semiconductor polythiophenes are oxidatively doped with ambient oxygen, which increases the conductivity, and thus increases the electrical conductivity. As a result, devices made from these materials have higher off-currents, and therefore lower current on / off ratios, so many of these materials are used in material processing and device manufacturing. Eliminate or minimize environmental oxygen in the meantime to prevent or minimize oxidative doping This precautionary measure raises manufacturing costs, and the appeal of certain polymer TFTs as an economical alternative to amorphous silicon technology, especially for large area devices, is diminished. These and other disadvantages are avoided or minimized in embodiments of the present invention, and electronic devices that have a strong resistance to oxygen and that exhibit a relatively high current on / off ratio are desired. Although there is a description of “rarely” and various solutions have been proposed (see, for example, Patent Documents 6 to 8), the level of improvement is not satisfactory, and further improvement is desired. .
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A JP 2003-261655 A JP 2003-264327 A JP 2003-268083 A International Publication No. 03/016599 Pamphlet US Patent Application Publication No. 2003/0105365 “Science” 289, 599 (2000) “Nature” 403, 521 (2000) Advanced Material, 2002, No. 2, page 99

  An object of the present invention is to provide an organic thin film transistor material which has good characteristics as a transistor and further suppresses deterioration with time, an organic thin film transistor, a field effect transistor and a switching element using the organic thin film transistor material.

  The above object of the present invention has been achieved by the following constitution.

(Claim 1)
An organic thin film transistor material comprising a compound represented by the following general formula (1):

Formula ^{(1) R 1 - (Z} ) n -R 2
(In the formula, R ¹ represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and R ² represents a monovalent substituent. However, R ¹ and R ² are not the same. Z is conjugated. (It represents a partial structure having a system part, and n represents an integer of 1 to 5.)
(Claim 2)
^2. The organic thin film transistor material according to claim 1, wherein R ² represents an aromatic hydrocarbon group, an aromatic heterocyclic group, or an aliphatic group.

(Claim 3)
The organic thin film transistor material according to claim 2, wherein the aliphatic group represented by R ² represents an alkyl group or a cycloalkyl group.

(Claim 4)
The organic thin-film transistor material according to any one of claims 1 to 3, wherein the Z includes an aromatic hydrocarbon ring or an aromatic heterocyclic ring.

(Claim 5)
The organic thin film transistor material according to claim 4, wherein the number of the aromatic hydrocarbon ring or the aromatic heterocyclic ring is 4 to 12.

(Claim 6)
The organic thin film transistor material according to claim 1, wherein the Z includes a five-membered ring.

(Claim 7)
The organic thin-film transistor material of any one of Claims 1-6 is used for a channel layer, The organic thin-film transistor characterized by the above-mentioned.

(Claim 8)
An organic charge transporting material and a gate electrode directly or indirectly in contact with the organic charge transporting material, and by applying a charge between the gate electrode and the organic charge transporting material, the organic charge transporting property A field effect transistor for controlling a current in a material, wherein the organic charge transporting material is the organic thin film transistor material according to any one of claims 1 to 6.

(Claim 9)
A switching element using the organic thin film transistor according to claim 7 or the field effect transistor according to claim 8.

  According to the present invention, it was possible to provide an organic thin film transistor material that has favorable characteristics as a transistor and further suppresses deterioration over time, an organic thin film transistor, a field effect transistor, and a switching element using the organic thin film transistor material.

  In the organic TFT material of the present invention, an organic TFT material useful for thin film transistor applications can be obtained by using the configuration defined in any one of claims 1 to 6. Further, the organic TFT of the present invention manufactured using the organic TFT material and the field effect transistor of the present invention have high carrier mobility, and the ratio between the maximum current value and the minimum current value when the gate voltage is changed, that is, ON. It was found that the transistor exhibited excellent transistor characteristics such as good / OFF characteristics and high durability. Moreover, it turned out that the switching element produced using this organic TFT or this field effect transistor shows a favorable switching characteristic.

  Hereinafter, details of each component according to the present invention will be sequentially described.

As the compound represented by the general formula (1) according to the present invention shows, by introducing substituents having different R ¹ and R ^{2 at} both ends (for example, a phenyl group and an alkyl group), the general formula It is considered that the orientation of the compound represented by (1) can be controlled. When a Si wafer is treated with octadecyltrichlorosilane (OTS), there is a high possibility that orientation control is facilitated by the interaction between the alkyl group and the treated surface. That is, the uniform orientation of the semiconductor layer makes it possible to provide an organic TFT material having excellent TFT characteristics.

<< Organic thin film transistor materials >>
The organic thin film transistor material of the present invention will be described.

In the general formula (1), examples of the aromatic heterocyclic group represented by R ¹ include a pyridyl group, pyrimidinyl group, furyl group, pyrrolyl group, imidazolyl group, benzoimidazolyl group, pyrazolyl group, pyrazinyl group, triazolyl group (for example, , 1,2,4-triazol-1-yl group, 1,2,3-triazol-1-yl group, etc.), oxazolyl group, benzoxazolyl group, thiazolyl group, isoxazolyl group, isothiazolyl group, furazanyl group, Thienyl group, quinolyl group, benzofuryl group, dibenzofuryl group, benzothienyl group, dibenzothienyl group, indolyl group, carbazolyl group, carbolinyl group, diazacarbazolyl group (one of the carbon atoms constituting the carboline ring is a nitrogen atom) Quinoxalinyl group, pyridazinyl group, Azinyl group, quinazolinyl group, and phthalazinyl group.

  The above aromatic heterocyclic group may be unsubstituted or may have a substituent. Examples of the substituent include an alkyl group (for example, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert group, -Butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (for example, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (for example, vinyl group, allyl group) Group), alkynyl group (eg, ethynyl group, propargyl group, etc.), aryl group (eg, phenyl group, naphthyl group, etc.), aromatic heterocyclic group (eg, furyl group, thienyl group, pyridyl group, pyridazinyl group, Pyrimidinyl, pyrazinyl, triazinyl, imidazolyl, pyrazolyl, thiazolyl, quinazolinyl , Phthalazinyl group, etc.), heterocyclic group (eg, pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (eg, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyl group) Oxy group, dodecyloxy group, etc.), cycloalkoxyl group (eg, cyclopentyloxy group, cyclohexyloxy group, etc.), aryloxy group (eg, phenoxy group, naphthyloxy group, etc.), alkylthio group (eg, methylthio group, ethylthio group) Propylthio group, pentylthio group, hexylthio group, octylthio group, dodecylthio group, etc.), cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), arylthio group (eg, phenylthio group, naphthylthio group, etc.) , Alkoxycarbonyl groups (for example, methyloxycarbonyl group, ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl groups (for example, phenyloxycarbonyl group, naphthyloxycarbonyl group) ), Sulfamoyl group (for example, aminosulfonyl group, methylaminosulfonyl group, dimethylaminosulfonyl group, butylaminosulfonyl group, hexylaminosulfonyl group, cyclohexylaminosulfonyl group, octylaminosulfonyl group, dodecylaminosulfonyl group, phenylaminosulfonyl) Group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbon) Bonyl group, pentylcarbonyl group, cyclohexylcarbonyl group, octylcarbonyl group, 2-ethylhexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyl group) Oxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonylamino group, Pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino , Phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group) Group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexyl) Ureido group, octylureido group, dodecylureido group, phenylureido group naphthylureido group, 2-pyridylaminoureido group), sulfinyl group For example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethylhexylsulfinyl group, dodecylsulfinyl group, phenylsulfinyl group, naphthylsulfinyl group, 2-pyridylsulfinyl group, etc.), alkylsulfonyl group (for example, Methylsulfonyl group, ethylsulfonyl group, butylsulfonyl group, cyclohexylsulfonyl group, 2-ethylhexylsulfonyl group, dodecylsulfonyl group, etc.), arylsulfonyl group (phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), amino group (For example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, Lino group, naphthylamino group, 2-pyridylamino group, etc.), halogen atom (eg, fluorine atom, chlorine atom, bromine atom), fluorinated hydrocarbon group (eg, fluoromethyl group, trifluoromethyl group, pentafluoroethyl) Group, pentafluorophenyl group, etc.), cyano group, nitro group, hydroxy group, mercapto group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.). These substituents may be further substituted with the above substituents. In addition, a plurality of these substituents may be bonded to each other to form a ring.

Examples of the aromatic hydrocarbon group represented by R ¹ include a phenyl group, a naphthyl group, an anthryl group, a phenanthryl group, a pentaphenyl group, a pentacenyl group, and the like. These aromatic hydrocarbon groups are substituted with the above substituents. May be.

Examples of the monovalent substituent represented by R ² include an aromatic hydrocarbon group, an aromatic heterocyclic group, and an aliphatic group. The aromatic hydrocarbon group and the aromatic heterocyclic group are the same as those described above for R ¹ . Examples are listed. Examples of the aliphatic group include an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, a cycloalkenyl group, and the like, which may be substituted with the above substituents. Among these, an alkyl group and a cycloalkyl group are preferable. Specifically, a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a pentyl group, a hexyl group, an octyl group, a dodecyl group, a tridecyl group, A tetradecyl group, a pentadecyl group, a cyclopentyl group, a cyclohexyl group, and the like. R ¹ and R ² must not be the same as specific groups.

  Z represents a partial structure having a conjugated moiety, but the entire Z may be a conjugated structure, or may not be a conjugated structure as a whole, but may be partially a conjugated structure.

  Hereinafter, although the specific example of a compound represented by General formula (1) based on this invention is shown, this invention is not limited to these.

  As an example of the synthesis of the compound represented by the general formula (1) according to the present invention, a synthesis example of the compound <2> is shown below, but the present invention is not limited thereto. Moreover, as a synthesis method, it can synthesize | combine with reference to the synthesis method of a conventionally well-known organometallic compound.

Synthesis example 1
Synthesis of compound <2>

The 200 ml three-necked flask was purged with nitrogen, 50 ml of a tetrahydrofuran solution containing 2.0 g of the compound <2-1> (compound described in Chem. Lett., 5, 1999, 443-444) was added, and the reaction system was reduced to −70 ° C. or lower. After cooling, 1.5 ml of n-butyllithium (1.6 mol / L) was added dropwise. After completion of the dropwise addition, the mixture was stirred at the same temperature for 1 hour, and then 5 ml of a tetrahydrofuran solution of 0.6 g of 1-bromododecane was dropped. After completion of the dropwise addition, the mixture was stirred at the same temperature for 1 hour and at room temperature for 1 hour, then washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure using a rotary evaporator. The residue was purified by column chromatography to obtain 1.8 g of a yellow solid. It was confirmed by ¹ H-NMR and mass spectrum that there was no contradiction with compound <2-2>.

The 200 ml three-necked flask was purged with nitrogen, 50 ml of a solution of compound <2-2> 1.8 g in tetrahydrofuran was added, the reaction system was cooled to −70 ° C. or lower, and n-butyllithium (1.6 mol / L) 1. 2 ml was added dropwise. After completion of the dropwise addition, the mixture was stirred at the same temperature for 1 hour, and then 5 ml of a tetrahydrofuran solution containing 0.2 g of trimethoxyborane was dropped. After completion of the dropwise addition, the mixture was stirred at the same temperature for 1 hour and at room temperature for 1 hour, and then 2 ml of concentrated hydrochloric acid was added and stirred for 30 minutes. After completion of stirring, the mixture was washed with saturated brine, dried over magnesium sulfate, and concentrated under reduced pressure using a rotary evaporator. The residue was washed by stirring with hexane to obtain 1.5 g of a yellow solid. It was confirmed by ¹ H-NMR and mass spectrum that there was no conflict with compound <2-3>.

A 200 ml three-necked flask was purged with nitrogen, 10 ml of an aqueous solution of compound <2-3> 1.5 g, bromobenzene 0.3 g, tetrakis (triphenylphosphine) palladium (0) 0.1 g, tetrahydrofuran 50 ml, potassium carbonate 2.0 g. And heated to reflux for 6 hours. After completion of the reaction, diatomaceous earth filtration was performed at room temperature, and the filtrate was washed with saturated brine, dried over magnesium sulfate, and then concentrated under reduced pressure using a rotary evaporator. The residue was purified by column chromatography to obtain 1.2 g of a yellow solid. It was confirmed by ¹ H-NMR and mass spectrum that there was no conflict with compound <2>.

<< Organic TFT, field effect transistor and switching element >>
The organic TFT, the field effect transistor and the switching element using them according to the present invention will be described. Here, the switching element is sometimes referred to as an organic TFT element depending on its usage, and is sometimes referred to as a field effect transistor element.

  The organic TFT material of the present invention can be used for a channel layer of an organic TFT or a field effect transistor, thereby providing a switching element (also referred to as a transistor device) that is driven satisfactorily. An organic TFT (organic thin film transistor) has a source electrode and a drain electrode connected by a semiconductor semiconductor channel as a channel on a support, and a top gate type having a gate electrode on the support and a support on the support First, it is roughly classified into a bottom gate type having a gate electrode and having a source electrode and a drain electrode connected by an organic semiconductor channel through a gate insulating layer.

  An organic thin film transistor material containing the compound represented by the general formula (1) according to the present invention is placed in a channel (also referred to as a channel layer) of a switching element using an organic TFT or a field effect transistor. Can be placed on the substrate by vacuum deposition, but the solution prepared by dissolving in an appropriate solvent and adding additives as necessary is cast substrate, spin coating, printing, inkjet method, ablation method, etc. It is preferable to install on top.

  In this case, the solvent for dissolving the organic TFT material of the present invention is not particularly limited as long as the organic TFT material can be dissolved to prepare a solution having an appropriate concentration. Specifically, diethyl ether or diisopropyl is used. Chain ether solvents such as ether, cyclic ether solvents such as tetrahydrofuran and dioxane, ketone solvents such as acetone and methyl ethyl ketone, alkyl halide solvents such as chloroform and 1,2-dichloroethane, toluene, o-dichlorobenzene, Aromatic solvents such as nitrobenzene and m-cresol, N-methylpyrrolidone, carbon disulfide and the like can be mentioned.

  In the present invention, the material for forming the source electrode, the drain electrode and the gate electrode is not particularly limited as long as it is a conductive material. Platinum, gold, silver, nickel, chromium, copper, iron, tin, antimony lead, tantalum, indium , Palladium, tellurium, rhenium, iridium, aluminum, ruthenium, germanium, molybdenum, tungsten, tin oxide / antimony, indium tin oxide (ITO), fluorine doped zinc oxide, zinc, carbon, graphite, glassy carbon, silver paste and carbon Paste, lithium, beryllium, sodium, magnesium, potassium, calcium, scandium, titanium, manganese, zirconium, gallium, niobium, sodium, sodium-potassium alloy, magnesium, lithium, aluminum, magnesium / Copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, lithium / aluminum mixture etc. are used, especially platinum, gold, silver, copper, aluminum, indium, ITO and Carbon is preferred. Alternatively, known conductive polymers whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylenedioxythiophene and polystyrenesulfonic acid, and the like are also preferably used. Among them, those having low electrical resistance at the contact surface with the semiconductor layer are preferable.

  As a method for forming an electrode, a method for forming an electrode using a known photolithographic method or a lift-off method, using a conductive thin film formed by a method such as vapor deposition or sputtering using the above as a raw material, a metal foil such as aluminum or copper There is a method of etching using a resist by thermal transfer, ink jet or the like. Alternatively, a conductive polymer solution or dispersion, or a conductive fine particle dispersion may be directly patterned by ink jetting, or may be formed from a coating film by lithography or laser ablation. Furthermore, a method of patterning an ink containing a conductive polymer or conductive fine particles, a conductive paste, or the like by a printing method such as relief printing, intaglio printing, planographic printing, or screen printing can also be used.

  Various insulating films can be used as the gate insulating layer, and an inorganic oxide film having a high relative dielectric constant is particularly preferable. Inorganic oxides include silicon oxide, aluminum oxide, tantalum oxide, titanium oxide, tin oxide, vanadium oxide, barium strontium titanate, barium zirconate titanate, lead zirconate titanate, lead lanthanum titanate, strontium titanate, Examples thereof include barium titanate, barium magnesium fluoride, bismuth titanate, strontium bismuth titanate, strontium bismuth tantalate, bismuth tantalate niobate, and yttrium trioxide. Of these, silicon oxide, aluminum oxide, tantalum oxide, and titanium oxide are preferable. Inorganic nitrides such as silicon nitride and aluminum nitride can also be suitably used.

  Examples of the method for forming the film include a vacuum process, a molecular beam epitaxial growth method, an ion cluster beam method, a low energy ion beam method, an ion plating method, a CVD method, a sputtering method, an atmospheric pressure plasma method, and a spray process. Wet processes such as coating methods, spin coating methods, blade coating methods, dip coating methods, casting methods, roll coating methods, bar coating methods, die coating methods, and other wet processes such as printing and ink jet patterning methods, etc. Can be used depending on the material.

  The wet process is a method of applying and drying a liquid in which fine particles of inorganic oxide are dispersed in an arbitrary organic solvent or water using a dispersion aid such as a surfactant as required, or an oxide precursor, for example, A so-called sol-gel method in which a solution of an alkoxide body is applied and dried is used. Among these, the atmospheric pressure plasma method and the sol-gel method are preferable.

  The method for forming an insulating film by plasma film formation under atmospheric pressure is a process in which a reactive gas is discharged under atmospheric pressure or a pressure near atmospheric pressure to excite reactive gas to form a thin film on a substrate. The method is described in JP-A-11-61406, JP-A-11-133205, JP-A-2000-121804, JP-A-2000-147209, JP-A-2000-185362 (hereinafter referred to as atmospheric pressure). Also called plasma method). Accordingly, a highly functional thin film can be formed with high productivity.

  In addition, as an organic compound film, polyimide, polyamide, polyester, polyacrylate, photo radical polymerization type, photo cation polymerization type photo curable resin, or a copolymer containing an acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, Also, cyanoethyl pullulan or the like can be used. As the method for forming the organic compound film, the wet process is preferable. An inorganic oxide film and an organic oxide film can be laminated and used together. The thickness of these insulating films is generally 50 nm to 3 μm, preferably 100 nm to 1 μm.

  Moreover, a support body is comprised with glass or a flexible resin-made sheet | seat, for example, a plastic film can be used as a sheet | seat. Examples of the plastic film include polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyethersulfone (PES), polyetherimide, polyetheretherketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC). And a film made of cellulose triacetate (TAC), cellulose acetate propionate (CAP), or the like. Thus, by using a plastic film, weight reduction can be achieved compared with the case where a glass substrate is used, portability can be improved, and resistance to impact can be improved.

  Below, the field effect transistor using the organic thin film formed using the organic TFT material of this invention is demonstrated.

  FIG. 1 is a diagram showing a configuration example of an organic TFT according to the present invention. In FIG. 2A, a source electrode 2 and a drain electrode 3 are formed on a support 6 with a metal foil or the like, an organic semiconductor layer 1 made of the organic TFT material of the present invention is formed between the two electrodes, and on that, An insulating layer 5 is formed, and a gate electrode 4 is further formed thereon to form a field effect transistor. FIG. 2B shows the organic semiconductor layer 1 formed between the electrodes in FIG. 1A so as to cover the entire surface of the electrode and the support using a coating method or the like. (C) shows that the organic semiconductor layer 1 is first formed on the support 6 by using a coating method or the like, and then the source electrode 2, the drain electrode 3, the insulating layer 5, and the gate electrode 4 are formed.

  In FIG. 4D, after forming the gate electrode 4 on the support 6 with a metal foil or the like, the insulating layer 5 is formed, and the source electrode 2 and the drain electrode 3 are formed on the metal foil or the like on the insulating layer 5. An organic semiconductor layer 1 made of the organic TFT material of the present invention is formed between the electrodes. In addition, the configuration as shown in FIGS.

  FIG. 2 is a diagram showing an example of a schematic equivalent circuit diagram of an organic TFT sheet.

  The organic TFT sheet 10 has a large number of organic TFTs 11 arranged in a matrix. 7 is a gate bus line of each TFT 11, and 8 is a source bus line of each TFT 11. An output element 12 is connected to the source electrode of each TFT 11, and this output 12 is, for example, a liquid crystal, an electrophoretic element or the like, and constitutes a pixel in the display device. The pixel electrode may be used as an input electrode of the photosensor. In the illustrated example, a liquid crystal as an output element is shown by an equivalent circuit composed of a resistor and a capacitor. 13 is a storage capacitor, 14 is a vertical drive circuit, and 15 is a horizontal drive circuit.

  EXAMPLES Hereinafter, although an Example demonstrates this invention, the embodiment of this invention is not limited to these.

Example 1
<< Preparation of Organic Thin Film Transistor Element 1 >>
A 0.2 μm thick thermal oxide film was formed on a Si wafer having a resistivity of 0.01 Ω · cm as a gate electrode to form a gate insulating layer, and then a surface treatment with octadecyltrichlorosilane was performed. Comparative compound <1> (poly (3-hexylthiophene) (regioregular, manufactured by Aldrich, average molecular weight 89000,
A chloroform solution of PHT)) was applied using an applicator, and air-dried to form a cast film (thickness 50 nm), followed by heat treatment at 50 ° C. for 30 minutes in a nitrogen atmosphere. Furthermore, gold was deposited on the surface of this film using a mask to form source and drain electrodes. An organic thin film transistor element 1 having a width of 100 μm, a thickness of 200 nm, a channel width W = 3 mm, and a channel length L = 20 μm was prepared.

<< Production of Organic Thin Film Transistor Elements 2-9 >>
An organic thin film transistor element 2 was produced in the same manner as the organic thin film transistor element 1, except that the comparative compound <1> was replaced with the comparative compound <2> (pentacene, a commercially available reagent manufactured by Aldrich was used after sublimation purification). . Further, organic thin film transistor elements 3 to 9 were produced in the same manner as the organic thin film transistor element 1 except that the comparative compound <1> was replaced with the exemplary compounds according to the present invention shown in Table 1.

<< Evaluation of Organic Thin Film Transistor Elements 1-9 >>
The organic thin film transistor elements 1 to 9 produced as described above showed good operating characteristics of a p-channel enhancement type FET. Further, for the organic thin film transistor elements 1 to 9, the carrier mobility is obtained from the saturation region of the IV characteristic, and further the ON / OFF ratio (the drain bias value is the ratio of the drain current when the gate bias is -50V and 0V, assuming the drain bias is -50V. ) The obtained element was left in the atmosphere for one month, and the carrier mobility and the ON / OFF ratio were obtained again. The results are shown in Table 1.

  From Table 1, it was found that the organic thin film transistor element of the present invention had better characteristics as a transistor and further suppressed deterioration over time as compared with comparison.

It is a figure which shows the structural example of the organic TFT which concerns on this invention. It is an example of the schematic equivalent circuit schematic of the organic TFT of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic-semiconductor layer 2 Source electrode 3 Drain electrode 4 Gate electrode 5 Insulating layer 6 Support body 7 Gate bus line 8 Source bus line 10 Organic TFT sheet 11 Organic TFT
12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit

Claims (9)

An organic thin film transistor material comprising a compound represented by the following general formula (1):
Formula ^{(1) R 1 - (Z} ) n -R 2
(In the formula, R ¹ represents an aromatic hydrocarbon group or an aromatic heterocyclic group, and R ² represents a monovalent substituent. However, R ¹ and R ² are not the same. Z is conjugated. (It represents a partial structure having a system part, and n represents an integer of 1 to 5.) ^2. The organic thin film transistor material according to claim 1, wherein R ² represents an aromatic hydrocarbon group, an aromatic heterocyclic group, or an aliphatic group. The organic thin film transistor material according to claim 2, wherein the aliphatic group represented by R ² represents an alkyl group or a cycloalkyl group. The organic thin-film transistor material according to any one of claims 1 to 3, wherein the Z includes an aromatic hydrocarbon ring or an aromatic heterocyclic ring. The organic thin film transistor material according to claim 4, wherein the number of the aromatic hydrocarbon ring or the aromatic heterocyclic ring is 4 to 12. The organic thin film transistor material according to claim 1, wherein the Z includes a five-membered ring. The organic thin-film transistor material of any one of Claims 1-6 is used for a channel layer, The organic thin-film transistor characterized by the above-mentioned. An organic charge transporting material and a gate electrode directly or indirectly in contact with the organic charge transporting material, and by applying a charge between the gate electrode and the organic charge transporting material, the organic charge transporting property A field effect transistor for controlling a current in a material, wherein the organic charge transporting material is the organic thin film transistor material according to any one of claims 1 to 6. A switching element using the organic thin film transistor according to claim 7 or the field effect transistor according to claim 8.

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