JP2006222251A - Organic semiconductor material, organic thin-film transistor, field effect transistor, and switching element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a useful organic semiconductor material, and to provide an organic TFT element using the organic semiconductor material which exhibits an excellent transistor characteristic and has a high durability as well. <P>SOLUTION: The organic semiconductor material has a repeated unit having such partial structures that at least an aromatic ring A having substitutional groups and an aromatic ring B having no substitutional group are coupled to each other therein, and compounds having Head-To-Tail type solid regularity are included in the repeated unit. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an organic semiconductor 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 a TFT element 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 has to be repeated many times to form each layer, and the apparatus cost and running cost have become enormous. For example, in the case of TFT elements, it is usually necessary to repeat processes such as sputtering, CVD, photolithography, etching, cleaning, etc. many times in order to form each layer, and elements are formed on the substrate through tens of processes. is doing. 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 have been reported in many 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 symmetrically fused to anthracene (see, for example, Patent Document 4), mono, oligo, and polydithienopyridines (see, for example, 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.

  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 and 8)), 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 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

  The object of the present invention is to design an organic semiconductor material that is useful for thin film transistor applications, and using the obtained organic semiconductor material, an organic TFT, a field effect transistor, having high carrier mobility and high durability, Furthermore, it is providing the switching element which has this organic TFT or this field effect transistor.

  The above object of the present invention has been achieved by the following configurations 1 to 6.

(Claim 1)
A repeating unit having a partial structure in which at least one of the aromatic ring A having a substituent and at least one of the unsubstituted aromatic ring B are connected to each other; An organic semiconductor material comprising a compound having stereoregularity of To-Tail type.

(Claim 2)
The organic semiconductor material according to claim 1, wherein the repeating unit is represented by the following general formula (1).

General formula (1)
-[A1-A2- (L) m-] n-
[In the formula, A1 represents a divalent group derived from an aromatic ring A having a substituent, A2 represents a partial structure in which an even number of unsubstituted aromatic rings B are connected, and L represents a divalent group. Represents a linking group. Moreover, the structure which can produce Head-To-Tail type stereoregularity by repeating the unit represented by General formula (1) 2 or more is represented. n represents an integer of 2 or more, and m represents an integer of 0 or 1 or more. ]
(Claim 3)
The organic semiconductor material according to claim 1 or 2, wherein the aromatic ring A or the aromatic ring B is a 5-membered aromatic heterocyclic ring.

(Claim 4)
An organic thin film transistor comprising the organic semiconductor material according to claim 1 in a semiconductor layer.

(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 In a field effect transistor that controls the current in a material,
A field effect transistor, wherein the organic charge transporting material is the organic semiconductor material according to claim 1.

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

  Useful for manufacturing organic thin-film transistors (hereinafter abbreviated as organic TFTs), molecular design of organic semiconductor materials, using these organic semiconductor materials, high carrier mobility, excellent ON / OFF characteristics, etc. An organic TFT and a field effect transistor having transistor characteristics and high durability were obtained. Moreover, by using them, it was possible to provide a switching element with good switching characteristics.

  In the organic semiconductor material of the present invention, an organic semiconductor material useful for thin film transistor applications can be obtained by using the configuration defined in any one of claims 1 to 3.

  In addition, organic TFTs and field-effect transistors manufactured using the organic semiconductor material exhibit excellent transistor characteristics such as high carrier mobility and good ON / OFF characteristics, and are highly durable. I understood it. Moreover, it turned out that the switching element produced using this organic TFT or this field effect transistor shows a favorable switching characteristic.

  In pentacene and the like that have been reported to have good TFT characteristics so far, it is known that molecules are regularly arranged while forming a π stack between molecules. However, conventionally known polythiophenes such as PHT have a problem that regular arrangements between molecules are only partially formed.

  For example, when the polythiophene described in Patent Documents 6, 7, 8 and the like is used, the π stack is only partially formed because of a huge polymer molecule, and the portion not related to the π stack is oriented. It was estimated that sufficient carrier mobility and ON / OFF characteristics could not be obtained because there were many disordered parts.

  Moreover, in the conventionally known PHT, substituents are introduced on all thiophene rings, which is not necessarily an advantageous structure from the viewpoint of forming a π stack between thiophene rings, but on the other hand, according to the organic semiconductor material of the present invention. The compound has a structure in which the side chain substituents have regularity in a certain direction as represented by the HT (Head to Tail) structure, and the positional relationship with adjacent molecules tends to be regular. The compound having such stereoregularity is easy to form a lamellar structure advantageous for exhibiting TFT characteristics, and is advantageous for stacking polymers by providing an HT structure among the positional regularity. We think that the characteristic was given. The HT structure according to the present invention will be described in detail later.

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

  As a result of various studies on the above problems, the present inventors have linked at least one aromatic ring A having a substituent and at least one unsubstituted aromatic ring B according to the present invention. A compound having a repeating unit having a partial structure, and a molecule designed to have Head-To-Tail type stereoregularity in the repeating unit has a soluble site (aromatic ring having a substituent). A portion having A) and a π stack forming portion (a portion having an unsubstituted aromatic ring B) as a partial structure, and a head-to-tail type steric structure in the repeating unit The compound having regularity can form a coating film having an ideal molecular arrangement as found in conventionally known pentacene, and as a result, TFT performance has been greatly improved.

  Moreover, the compound which concerns on the organic-semiconductor material of this invention is a compound which can form a macroscopic HT structure (Head-To-Tail type structure) while having the site | part which promotes (pi) stack formation.

《Organic semiconductor material》
The organic semiconductor material of the present invention has a repeating unit having a partial structure in which at least one of the aromatic ring A having a substituent and at least one of the unsubstituted aromatic ring B are connected, and A compound having stereoregularity of Head-To-Tail type in the repeating unit will be described.

(Aromatic ring A having a substituent)
As the aromatic ring A according to the present invention, an aromatic heterocyclic ring, an aromatic hydrocarbon ring and the like can be used. As the aromatic heterocyclic ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a pyridine ring. , Pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, benzimidazole ring, oxadiazole ring, triazole ring, imidazole ring, pyrazole ring, thiazole ring, thienothiophene ring, dithienobenzene ring, indole ring, benzimidazole ring, Benzothiazole ring, benzoxazole ring, quinoxaline ring, quinazoline ring, phthalazine ring, carbazole ring, carboline ring, diazacarbazole ring (one of the carbon atoms of the hydrocarbon ring constituting the carboline ring is further substituted with a nitrogen atom) A ring is shown). Furthermore, the aromatic heterocyclic ring may have a substituent described later.

  As aromatic hydrocarbon rings, benzene ring, biphenyl ring, naphthalene ring, azulene ring, anthracene ring, phenanthrene ring, pyrene ring, chrysene ring, naphthacene ring, triphenylene ring, o-terphenyl ring, m-terphenyl ring. Ring, p-terphenyl ring, acenaphthene ring, coronene ring, fluorene ring, fluoranthrene ring, naphthacene ring, pentacene ring, perylene ring, pentaphen ring, picene ring, pyrene ring, pyranthrene ring, anthraanthrene ring, etc. It is done. Furthermore, the aromatic hydrocarbon ring may have a substituent described later.

  Among these, a 5-membered aromatic heterocycle is preferably used, and examples thereof include a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an imidazole ring, a pyrazole ring, and a thiazole ring.

(Substituent)
Examples of the substituent of the aromatic ring A 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, tetradecyl group). 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, naphthyl group, etc.), aromatic heterocyclic group (for example, furyl group, thienyl group, pyridyl group, pyridazinyl group, pyrimidinyl group, pyrazinyl group, triazinyl group, imidazolyl group, pyrazolyl group, thiazolyl group, quinazolinyl group , Phthalazinyl group, etc.), heterocyclic group (for example, pyrrolidyl group, Midazolidyl group, morpholyl group, oxazolidyl group, etc.), alkoxy group (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy 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, octylthio 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, etc.) Ethyloxycarbonyl group, butyloxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, 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, 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) 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 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) Group, phenylaminocarbonyl group, naphthylaminocarbonyl group, 2-pyridylaminocarbonyl group, etc.), ureido group (for example, methylureido group, ethylureido group, pentylureido group, cyclohexylureido group, octylureido group, dodecylureido group, phenyl) Ureido group naphthylureido group, 2-pyridylaminoureido group, etc.), sulfinyl group (for example, methylsulfinyl group, ethylsulfinyl group, butyl) Rufinyl 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, dimethyl) Amino group, butylamino group, cyclopentylamino group, 2-ethylhexylamino group, dodecylamino group, anilino group, naphthylamino group, 2-pyridylamino group, etc.), halogen Atom (for example, fluorine atom, chlorine atom, bromine atom, etc.), fluorinated hydrocarbon group (for example, fluoromethyl group, trifluoromethyl group, pentafluoroethyl group, pentafluorophenyl group, etc.), cyano group, nitro group, Examples thereof include a hydroxy group, a mercapto group, and a silyl group (for example, a trimethylsilyl group, a triisopropylsilyl group, a triphenylsilyl group, and a phenyldiethylsilyl group).

  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.

  A preferable substituent is an alkyl group, and among them, a preferable substituent is an alkyl group having 2 to 20 carbon atoms, and particularly preferably an alkyl group having 6 to 12 carbon atoms.

(Unsubstituted aromatic ring B)
Examples of the aromatic ring of the unsubstituted aromatic ring B according to the present invention include an aromatic heterocycle and an aromatic hydrocarbon ring, and the aromatic heterocycle and the aromatic hydrocarbon ring are both And the aromatic heterocycle and the aromatic hydrocarbon ring described in the above-mentioned aromatic ring A having a substituent, respectively.

(Head-To-Tail type stereoregularity)
The head-to-tail type stereoregularity according to the present invention will be described using the general formula (1) and the following general formulas (2) and (3).

  Paying attention to the repeating structure forming the partial structure of the compound according to the organic semiconductor material of the present invention, the case where the atom connected to the atom present at one end of the repeating unit has a substituent is “Head”, the other of the repeating unit If the atom connected to the atom existing at the end of the is defined as “Tail”, it is a structure that produces Head-To-Tail type stereoregularity by repeating this unit.

  The case where the compound according to the present invention has a head-to-tail type stereoregularity can be specifically expressed by, for example, the following general formula (2) or the following general formula (3).

  Here, the general formula (2) is a case where A1 in the general formula (1) corresponds to one thiophene ring having a substituent, A2 corresponds to one unsubstituted thiophene ring, and L does not exist. . Further, the general formula (3) is a case where A1 in the general formula (1) corresponds to one thiophene ring having a substituent, A2 corresponds to two unsubstituted thiophene rings, and L does not exist.

  In the general formula (2), there is only one direction of the substituent on the thiophene ring with respect to the main chain, and in the general formula (3), the direction of the substituent on the thiophene ring with respect to the main chain is Exists in both directions. When there is an even number of unsubstituted thiophene rings, the steric configuration represented by the general formula (3) is obtained, and a more preferable steric configuration can be taken for the expression of transistor characteristics.

(Repeat unit)
The compound according to the present invention has a repeating unit having a partial structure in which at least one of the aromatic ring A having the above substituent and at least one of the unsubstituted aromatic ring B are connected. The repeating unit represented by the general formula (1) is preferably used.

  In the general formula (1), A1 is a divalent group derived from an aromatic ring A having a substituent, and A2 is a divalent group derived from an unsubstituted aromatic ring B.

  The divalent linking group represented by L in the general formula (1) may be a hydrocarbon group such as alkylene, alkenylene, alkynylene, and arylene, and may contain a hetero atom. A divalent linking group derived from a compound having an aromatic heterocycle (also referred to as a heteroaromatic compound), such as, 5-diyl group or pyrazine-2,3-diyl group, or oxygen Or a chalcogen atom such as sulfur. Further, it may be a group such as an alkylimino group, a dialkylsilanediyl group, or a diarylgermandiyl group that connects and connects heteroatoms.

《Compound end group》
The terminal group of the compound according to the present invention will be described.

  Preferred groups as terminal groups of the compounds according to the present invention include aryl groups (eg, 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.), 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.).

  Specific examples of the compound according to the present invention are shown below, but the present invention is not limited thereto.

<< Organic TFT, field effect transistor and switching element >>
The organic TFT of the present invention, the field effect transistor and the switching element using them 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.

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

  In order to install the organic semiconductor material according to the present invention in a semiconductor layer of a switching element using an organic TFT or a field effect transistor, it can be installed on a substrate by vacuum deposition, but it can be dissolved in an appropriate solvent and used as necessary. A solution prepared by adding an additive is preferably placed on a substrate by cast coating, spin coating, printing, an inkjet method, an ablation method, or the like.

  In this case, the solvent for dissolving the organic semiconductor material of the present invention is not particularly limited as long as the organic semiconductor 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, magnesi A copper / gold mixture, a magnesium / silver mixture, a magnesium / aluminum mixture, a magnesium / indium mixture, an aluminum / aluminum oxide mixture, a lithium / aluminum mixture, etc., in particular, platinum, gold, silver, copper, aluminum, indium, ITO and carbon are preferred. Alternatively, a known conductive polymer whose conductivity is improved by doping or the like, for example, conductive polyaniline, conductive polypyrrole, conductive polythiophene, a complex of polyethylenedioxythiophene and polystyrenesulfonic acid, or the like is 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, or 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.

  Below, the field effect transistor using the organic thin film formed using the organic-semiconductor 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 by a metal foil or the like, an organic semiconductor layer 1 made of the organic semiconductor material of the present invention is formed between the two electrodes, and a substrate is formed thereon. 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 semiconductor 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, this invention is not limited to these.

Example 1
<< Preparation of Organic Thin Film Transistor Element 1 >>
A Si oxide having a specific resistance 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 cast film (thickness 50 nm) was prepared by applying a chloroform solution of the comparative compound (1) (poly (3-hexylthiophene) (regio regular, Aldrich, average molecular weight 89000, PHT)) using an applicator and air-drying. ) And 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.

<< Production of Organic Thin Film Transistor Element 2 >>
In the production of the organic thin film transistor element 1, the organic thin film transistor element was similarly obtained except that the comparative compound (1) was replaced with the comparative compound (2) (exemplary compound 3 described in US 2003/0164495). 2 was produced.

<< Production of Organic Thin Film Transistors 3-6 >>
Organic thin film transistor elements 3 to 6 were produced in the same manner as in the production of the organic thin film transistor element 1, except that the compound (1) was replaced with the compound shown in Table 1 (organic semiconductor material of the present invention).

  The organic thin film transistor elements 1 to 6 fabricated as described above showed good operating characteristics of a p-channel enhancement type FET. Further, for the organic thin film transistor elements 1 to 6, the carrier mobility is obtained from the saturation region of the IV characteristic, and further the ON / OFF ratio (the drain bias is −50 V and the drain current value when the gate bias is −50 V and 0 V is set). 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 obtained results are shown in Table 1.

  From Table 1, it can be seen that the organic thin film transistor of the present invention exhibits excellent transistor characteristics even immediately after fabrication and has high durability with little deterioration with time.

Example 2
The organic thin film transistor element was the same as the organic thin film transistor element 1 except that the comparative compound (1) in Example 1 was replaced with the comparative compound (3) (pentacene, a commercially available reagent manufactured by Aldrich). 11 was produced.

  Furthermore, organic thin-film transistor elements 12-15 were produced by the same method as the organic thin-film transistor element 1 except that the comparative compound (1) was replaced with the exemplified compound which is the organic semiconductor material of the present invention shown in Table 2.

  The organic thin film transistor elements 1 and 12 to 15 manufactured as described above exhibited good operating characteristics of p-channel enhancement type FETs. Further, for the organic thin film transistor elements 1 and 11 to 15, from the saturation region of the IV characteristics, the carrier mobility and the ON / OFF ratio (the drain bias is −50 V, the drain current value when the gate bias is −50 V and 0 V are set) 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 obtained results are shown in Table 2.

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 (6)

A repeating unit having a partial structure in which at least one of the aromatic ring A having a substituent and at least one of the unsubstituted aromatic ring B are connected to each other; An organic semiconductor material comprising a compound having stereoregularity of To-Tail type. The organic semiconductor material according to claim 1, wherein the repeating unit is represented by the following general formula (1).
General formula (1)
-[A1-A2- (L) m-] n-
[In the formula, A1 represents a divalent group derived from an aromatic ring A having a substituent, A2 represents a partial structure in which an even number of unsubstituted aromatic rings B are connected, and L represents a divalent group. Represents a linking group. Moreover, the structure which can produce Head-To-Tail type stereoregularity by repeating the unit represented by General formula (1) 2 or more is represented. n represents an integer of 2 or more, and m represents an integer of 0 or 1 or more. ] The organic semiconductor material according to claim 1 or 2, wherein the aromatic ring A or the aromatic ring B is a 5-membered aromatic heterocyclic ring. An organic thin film transistor comprising the organic semiconductor material according to claim 1 in a semiconductor layer. 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 In a field effect transistor that controls the current in a material,
A field effect transistor, wherein the organic charge transporting material is the organic semiconductor material according to claim 1. A switching element comprising the organic transistor according to claim 4 or the field effect transistor according to claim 5.

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