JP2006040934A - Organic thin film transistor material, organic thin film transistor, field effect transistor and switching element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic TFT having both high carrier mobility and high durability by molecule designing the organic TFT material useful for a thin film transistor application and using the obtained organic TFT material and to further provide a field effect transistor using the organic TFT and a switching element having the organic TFT or the field effect transistor. <P>SOLUTION: The organic thin film transistor material contains a compound having substitute groups in the fourth place and the fifth place and having thiophene rings at both ends and combining with a conjugate system containing a composite aromatic ring at the second place. <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. A plurality of types of semiconductor layers, such as p-type and n-type, are also stacked on the semiconductor portion that is the key to the switching operation. 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 formation of such a conventional TFT element using a Si material includes a process at a high temperature, the substrate material is restricted to 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. These compounds are reported in numerous papers such as organic laser oscillation elements as discussed in Non-Patent Document 1, etc., and Non-Patent Document 2, for example, in addition to charge transport materials for organic EL elements. Application to organic thin-film transistors is expected. 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 The development of a semiconducting composition using a novel charge transporting material that exhibits high carrier mobility, and is limited to only a limited number of types of compounds (for example, see Non-Patent Documents 1, 2, and 3). It was.

  In addition, in Japanese Patent Application Laid-Open No. 2003-292588, US Patent Application Publication Nos. 2003/136958, 2003/160230, and 2003/164495, “integrated circuit logic element for microelectronics and polymer TFT However, many 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. To eliminate or minimize oxidative doping by eliminating environmental oxygen in between This precautionary measure raises the cost of manufacturing, 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.

Therefore, an electronic device having a strong resistance against oxygen and a relatively high current on / off ratio is desired ", and various solutions have been proposed (for example, patents). (Refs. 6, 7, 8, and 9)), but the level of improvement is not satisfactory, and further improvements are 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 2002-1000078 A JP 2003-261655 A JP 2003-264327 A JP 2003-268083 A “Science” 289, 599 (2000) “Nature” 403, 521 (2000) Advanced Material, 2002, No. 2, page 99

  An object of the present invention is to design an organic TFT material (organic thin film transistor material) useful for thin film transistor applications, and to use the obtained organic TFT material to provide an organic TFT (organic) with high carrier mobility and high durability. A thin film transistor), a field effect transistor using the organic TFT, and a switching element having the organic TFT or the field effect transistor.

  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 having a thiophene ring having substituents at the 4-position and 5-position at both ends, each bonded with a conjugated system containing a heteroaromatic ring at the 2-position.

(Claim 2)
The organic thin film transistor material according to claim 1, wherein the heteroaromatic ring is a thiophene ring.

(Claim 3)
The organic thin film transistor material according to claim 2, wherein the number of the thiophene rings is 8 or more and 20 or less.

(Claim 4)
The organic thin-film transistor material of any one of Claims 1-3 is used for a channel layer, The organic thin-film transistor characterized by the above-mentioned.

(Claim 5)
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 The field effect transistor which controls the electric current in material, This organic charge transport material is the organic thin-film transistor material of any one of Claims 1-3, The field effect transistor characterized by the above-mentioned.

(Claim 6)
A switching element comprising the organic thin film transistor according to claim 4 or the field effect transistor according to claim 5.

  According to the present invention, an organic TFT material useful for a thin film transistor application can be designed, and an organic TFT having high carrier mobility and high durability can be provided by using the obtained organic TFT material. A field effect transistor using an organic TFT, a switching element having the organic TFT or the field effect transistor could be provided.

  Pentacene is well known as an organic semiconductor material, but since pentacene is insoluble, a film can be conventionally formed only by vapor deposition, and it is difficult to produce a coating film. A thiophene oligomer having no substituent as represented by unsubstituted 6T easily forms a π stack between molecules, but is insoluble, and has a problem that a film can be formed only by vapor deposition like pentacene. Further, since the activity at the 5-position of the terminal thiophene is high, there was a problem in the temporal stability of the material and the coating film.

  On the other hand, materials that can be applied such as thiophene polymers represented by PHT have been proposed. However, in the case of polymers having a molecular weight distribution, the formation of a coating film causes partial formation of π stacks, which disrupts molecular alignment. There were many portions that were insufficient to obtain satisfactory TFT performance.

  When a compound having a thiophene ring having substituents at the 4-position and 5-position according to the present invention at both ends and bonded with a conjugated system each containing a heteroaromatic ring at the 2-position is improved in the following points: Therefore, it is possible to provide an organic TFT material having ideal TFT characteristics.

  1) The solubility is improved by introducing a substituent.

  2) Inactivation by capping the 5-position of the active terminal thiophene ring with a substituent improves the temporal stability of the material and the coating film.

  The compound which has a thiophene ring having substituents at the 4-position and 5-position at both ends according to the present invention and is bonded with a conjugated system each containing a heteroaromatic ring at the 2-position will be described. Here, examples of the substituent at the 4-position and 5-position include an alkyl group (for example, methyl group, ethyl group, propyl group, isopropyl group, tert-butyl group, pentyl group, hexyl group, octyl group, dodecyl group, tridecyl group). Group, tetradecyl group, pentadecyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (eg, vinyl group, allyl group, etc.), alkynyl group (eg, ethynyl group, propargyl group, etc.), Aryl group (for example, phenyl group, p-chlorophenyl group, mesityl group, tolyl group, xylyl group, naphthyl group, anthryl group, azulenyl group, acenaphthenyl group, fluorenyl group, phenanthryl group, indenyl group, pyrenyl group, biphenylyl group, etc.) , Aromatic heterocyclic group (for example, furyl group, thienyl group) Pyridyl group, pyridazyl group, pyrimidyl group, pyrazyl group, triazyl group, imidazolyl group, pyrazolyl group, thiazolyl group, benzoimidazolyl group, benzoxazolyl group, quinazolyl group, phthalazyl group, etc.), heterocyclic group (for example, pyrrolidyl group, Imidazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxyl group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxyl group (for example, 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, octyl) Thio group, dodecylthio group etc.), cycloalkylthio group (eg cyclopentylthio group, cyclohexylthio group etc.), arylthio group (eg phenylthio group, naphthylthio group etc.), alkoxycarbonyl group (eg methyloxycarbonyl group, ethyloxy) Carbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylamino) Sulfonyl, dimethylaminosulfonyl, butylaminosulfonyl, hexylaminosulfonyl, cyclohexylaminosulfonyl, octylaminosulfonyl, dodecylaminosulfonyl Phonyl group, phenylaminosulfonyl group, naphthylaminosulfonyl group, 2-pyridylaminosulfonyl group, etc.), acyl group (for example, acetyl group, ethylcarbonyl group, propylcarbonyl 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, ethylcarbonyloxy group, butylcarbonyloxy group, octylcarbonyloxy group, dodecylcarbonyloxy group) Group, phenylcarbonyloxy group, etc.), amide group (for example, methylcarbonylamino group, ethylcarbonylamino group, dimethylcarbonylamino group, propylcarbonyl) Amino group, pentylcarbonylamino group, cyclohexylcarbonylamino group, 2-ethylhexylcarbonylamino group, octylcarbonylamino group, dodecylcarbonylamino group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, aminocarbonyl group) , Methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl group, phenylaminocarbonyl group, naphthylamino Carbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentyl) Raid group, cyclohexylureido group, octylureido group, dodecylureido group, phenylureido group, naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group) 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 (for example, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridyl group) Diylsulfonyl group, etc.), amino group (for example, amino group, ethylamino group, dimethylamino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group) Group), halogen atom (eg fluorine atom, chlorine atom, bromine atom etc.), fluorinated hydrocarbon group (eg fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group etc.), cyano Group, silyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethylsilyl group, etc.).

  These substituents may be further substituted with the above substituents, or a plurality thereof may be bonded to each other to form a ring. Among them, a preferable substituent is an alkyl group, more preferably an alkyl group having 2 to 20 carbon atoms, and particularly preferably an alkyl group having 6 to 12 carbon atoms.

  The conjugated system is one in which multiple bonds and single bonds are alternately bonded. In the present invention, a conjugated system includes a heteroaromatic ring such as a thiophene ring or a furan ring. The heteroaromatic ring may be substituted with the substituent described as the substituent at the 4- and 5-positions. In the present invention, the heteroaromatic ring is preferably a thiophene ring, and more preferably 8 or more and 20 or less.

  Hereinafter, specific examples of the compound according to the present invention having a thiophene ring having substituents at the 4-position and 5-position at both ends, each bonded with a conjugated system containing a heteroaromatic ring at the 2-position will be shown. The invention is not limited to these.

<< 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. The organic TFT has a source electrode and a drain electrode connected by an organic semiconductor channel as a channel on a support, a top gate type having a gate electrode through a gate insulating layer thereon, and a gate on the support first. A bottom-gate type having an electrode and having a source electrode and a drain electrode connected by an organic semiconductor channel through a gate insulating layer.

  An organic TFT or a field effect transistor was used as a compound according to the present invention having a thiophene ring having substituents at the 4-position and 5-position at both ends, and binding each with a conjugated system containing a heteroaromatic ring at the 2-position. To install in the channel of the switching element (also referred to as channel layer), it can be installed on the substrate by vacuum deposition, but it is cast-coated with a solution prepared by dissolving in an appropriate solvent and adding additives as necessary. It is preferable to install on the substrate by spin coating, printing, inkjet method, ablation method or the like.

  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, cycloalkane solvents such as N-methylpyrrolidone, carbon disulfide, and cyclohexane can be used.

  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, magnesi Copper / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide mixture, lithium / aluminum mixture, etc., but especially platinum, gold, silver, copper, aluminum, indium, ITO And carbon are 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 the 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, the weight can be reduced as compared with the case of using a glass substrate, the portability can be improved, and the resistance to impact can be improved.

  Hereinafter, an organic TFT using an organic thin film formed using the organic TFT material of the present invention (the same applies to a field effect transistor) will be described.

  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 by a metal foil or the like, an organic semiconductor layer 1 made of the organic thin film transistor 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 thin film transistor 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.

  Hereinafter, the present invention will be described by way of examples. However, embodiments of the present invention are not limited to these examples.

Example 1
(Synthesis of Exemplified Compound 1)

  (Synthesis of Intermediate 1) Under a nitrogen atmosphere, 30 g of 2,3-dibromothiophene and 1.3 g of dichloro [1,3-bis (diphenylphosphino) propane] nickel (II) were added to 100 ml of diethyl ether and stirred to hexyl. 150 ml of magnesium bromide (2M hexane solution) was added dropwise. After refluxing for 2 hours, the reaction mixture was washed with water and saturated brine, and dried over magnesium sulfate. After the solvent was distilled off, 20 g of Intermediate 1 was obtained by column chromatography (yield 65%).

  (Synthesis of Intermediate 2) 20 g of the obtained Intermediate 1 was dissolved in a mixed solvent of 100 ml of dichloroethane and 100 ml of acetic acid, and 15.5 g of bromosuccinimide was added in portions while cooling with ice. After stirring for 1 hour, the mixture was further stirred at room temperature for 2 hours, and the resulting reaction mixture was washed with 5% aqueous potassium hydroxide solution, water and saturated brine. After the solvent was distilled off, the target product was isolated by column chromatography to obtain 21.2 g of Intermediate 2 (yield 81%).

  (Synthesis of Intermediate 3) Under a nitrogen atmosphere, 21.2 g of Intermediate 2 was dissolved in 60 ml of THF, and the obtained solution was slowly dropped into 100 ml of THF in which 5.4 g of magnesium was suspended. After completion of dropping, the mixture was stirred at room temperature for 2.5 hours, and further stirred at 50 ° C. for 1 hour. The obtained reaction mixture was suspended in 22.8 g of 5,5′-dibromo-2,2′-bithiophene and 0.7 g of dichloro [1,3-bis (diphenylphosphino) propane] nickel (II). The solution was slowly added dropwise to 200 ml of THF solution. After completion of the dropwise addition, the mixture was stirred for 18 hours under reflux. The obtained reaction mixture was washed with water, 5% hydrochloric acid and saturated brine, and then dried over magnesium sulfate. After the solvent was distilled off, 13.6 g of Intermediate 3 was obtained by column chromatography (43% yield).

  (Synthesis of Intermediate 4) Under a nitrogen atmosphere, 13.6 g of Intermediate 3 was dissolved in 250 ml of THF and cooled to -78 ° C. Under cooling, 19 ml of 1.6M n-lithium bromide / hexane solution was slowly added dropwise, and the mixture was further stirred for 2 hours. Next, 6.6 g of trimethoxyboron was dropped into the mixture and stirred for 1 hour, and further stirred at room temperature for 2 hours. The obtained reaction mixture was added to 5% hydrochloric acid and stirred at room temperature for 1 hour, and then washed with water and saturated brine. The solvent was distilled off to obtain Intermediate 4.

  (Synthesis of Exemplified Compound 1) In a nitrogen atmosphere, 8.5 g of intermediate 4,5,5′-dibromo-2,2′-bithiophene obtained above in 150 ml of THF, tetrakis (triphenylphosphine) palladium (0) 1.6 g, 20% aqueous potassium carbonate solution 30 ml was added, and the mixture was stirred under reflux for 24 hours. The obtained reaction mixture was washed with water and saturated brine, and then the solvent was distilled off. Thus, 7.2 g of Compound 1 was obtained by column chromatography (yield 28%). From the HPLC measurement result, it was confirmed that the purity of the obtained compound 1 was 99% or more.

Example 2
A silicon oxide having a resistivity of 0.01 Ω · cm as a gate electrode was formed with a thermal oxide film having a thickness of 2000 mm to form a gate insulating layer, and then surface treatment with octadecyltrichlorosilane was performed. A chloroform solution of the comparative compound (1) (poly (3-hexylthiophene) (regioregular, Aldrich, average molecular weight 89000, PHT)) was applied using an applicator and dried naturally to give a cast film (thickness 50 nm) And was heat-treated 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.

  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). .

  Further, organic thin film transistor elements 3 to 8 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.

  The organic thin film transistor elements 1 to 8 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 8, the carrier mobility is obtained from the saturation region of the IV characteristics, and further the ON / OFF ratio (the drain bias is −50V and the drain current value when the gate bias is −50V and 0V). Ratio). 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 the results shown in Table 1, it was found that the organic thin film transistor of the present invention had good characteristics as a transistor and further suppressed deterioration over time.

It is a figure which shows the structural example of the organic TFT of 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 (6)

An organic thin film transistor material comprising a compound having a thiophene ring having substituents at the 4-position and 5-position at both ends, each bonded with a conjugated system containing a heteroaromatic ring at the 2-position. The organic thin film transistor material according to claim 1, wherein the heteroaromatic ring is a thiophene ring. The organic thin film transistor material according to claim 2, wherein the number of the thiophene rings is 8 or more and 20 or less. The organic thin-film transistor material of any one of Claims 1-3 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 The field effect transistor which controls the electric current in material, This organic charge transport material is the organic thin-film transistor material of any one of Claims 1-3, The field effect transistor characterized by the above-mentioned. A switching element comprising the organic thin film transistor according to claim 4 or the field effect transistor according to claim 5.

Images