JP5034196B2 - Organic semiconductor material, organic semiconductor film, organic semiconductor device, and organic thin film transistor - Google Patents

Description

  The present invention relates to an organic semiconductor material, an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor.

  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 in paper media has been increasingly digitized, and as a mobile display medium that is thin, light, and portable, electronic paper or digital paper can be used. The need for is increasing.

  In general, in a flat panel display device, a display medium is formed using elements utilizing liquid crystal, organic EL (organic electroluminescence), 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 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 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., for example, Non-Patent Document 2, etc., in addition to charge transport materials for organic EL elements. Application to organic thin film transistor elements (organic TFT elements) 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 5-membered aromatic heterocycles are condensed symmetrically to anthracene (for example, see Patent Document 4), mono-, oligo- and polydithienopyridines (for example, see Patent Document 5), polythiophene, polythienylene vinylene, High conjugated content such as poly-p-phenylene vinylene There are not only limited types of compounds (see, for example, Non-Patent Documents 1 to 3), and materials that exhibit sufficient carrier mobility and ON / OFF ratio while maintaining sufficient solubility in a solvent are observed. It has not been issued.

  Recently, it has been reported that a single crystal of rubrene, which is a highly soluble acene, has a very high mobility (see, for example, Non-Patent Document 4). The film formed by solution casting is amorphous, and sufficient mobility is not obtained.

Further, a compound in which a functional group is added to pentacene, which is a compound having high carrier mobility by vacuum deposition, is disclosed, and it has been reported that relatively good carrier mobility can be obtained by solution coating. (For example, see Patent Document 6.)
However, it is known that acene-based compounds such as rubrene and pentacene are easily oxidized by air and converted into an oxidant called endperoxide, which greatly deteriorates the performance as a field effect transistor. There are still problems to be solved regarding storage stability and coating film stability.

  With respect to the stability over time of such an organic semiconductor element, for example, Japanese Patent Application Laid-Open No. 2003-292588, US Patent Application Publication Nos. 2003/136958, 2003/160230, and 2003/164495. "Using polymer TFTs as integrated circuit logic elements for microelectronics greatly improves their mechanical durability and extends their useful life. However, many of the semiconductor polythiophenes are oxidized by surrounding oxygen. It is considered unstable when exposed to air because it increases the conductivity and results in a large off-current for devices made from these materials, and thus a low current on / off ratio. Therefore, many of these materials eliminate environmental oxygen during material processing and device manufacturing. Care must be taken to avoid or minimize oxidative doping, as this precautionary measure increases manufacturing costs, and as an economical alternative to amorphous silicon technology, especially for large area devices. The attractiveness of certain polymer TFTs is diminished, and these and other disadvantages are avoided or minimized in embodiments of the present invention, thus having a strong resistance to oxygen and comparison As an electronic device that exhibits a high current ON / OFF ratio is desired, "the issue of how to prevent organic semiconductor materials from deteriorating over time is a major issue in commercialization. It has become an issue.

  As an example of an acene compound that is relatively stable against oxidation, in Non-Patent Documents 5 and 6, and Patent Document 7, some compounds in which the 6th and 13th positions of pentacene are substituted with silylethynyl groups are used. There are some reports that stability is good.

  However, these reports only describe qualitative properties in the text that stability against oxidation has been improved, and have not yet obtained stability enough to withstand practical use.

In Non-Patent Document 7, a part of pentacene mother nucleus of a compound in which 6th and 13th positions of pentacene are substituted with a silylethynyl group is substituted with an electron withdrawing group such as a halogen atom or a cyano group. Attempts have been made to increase the potential, but these compounds have a maximum mobility of only 4.5 × 10 ⁻² cm ² / Vs, which is an organic compound that combines high mobility and device durability. Semiconductor materials have not yet been obtained.
JP-A-5-55568 Japanese Patent Laid-Open No. 5-190877 JP-A-8-264805 JP-A-11-195790 JP 2003-155289 A International Publication No. 03/016599 Pamphlet US Pat. No. 6,690,029B1 “Science” 289, 599 (2000) “Nature”, 403, 521 (2000) Advanced Material, 2002, No. 2, page 99 Science, vol. 303 (2004), page 1644 Org. Lett. , Vol. 4 (2002), page 15 J. et al. Am. Chem. Soc. , Vol. 127 (2005), p. 4986 Org. Lett. , Vol. 7 (2005), p. 3163

  Accordingly, an object of the present invention is an organic semiconductor material which is manufactured by a simple process, has good characteristics as a transistor, is stable against oxygen in the air, and sufficiently suppresses deterioration over time, and an organic semiconductor using the organic semiconductor material It is to provide a film, an organic semiconductor device and an organic thin film transistor.

  The above object of the present invention is achieved by the following configurations.

  (1) An organic semiconductor material comprising a compound represented by the following general formula (1).

(In the formula, Y ₁ and Y ₂ are each substituted with an unsubstituted methyl group, ethyl group or propyl group which may be linked to each other , or from an unsubstituted cycloalkyl ring, cycloalkenyl ring or heterocyclic ring. Represents an alicyclic 5-membered or 6-membered structure selected, Z represents an unsubstituted aromatic ring, and n represents an integer of 0 or 1.)
(2) The organic semiconductor material as described in (1) above, wherein Y ₁ = Y ₂ and n = 1 in the compound represented by the general formula (1).

(3) The organic semiconductor material as described in (1) or (2) above, wherein in the compound represented by the general formula (1), Y ₁ and Y ₂ are both heterocyclic rings.

  (4) In the compound represented by the general formula (1), the aromatic ring represented by Z is an unsubstituted benzene ring, any one of the above (1) to (3) The organic semiconductor material described in 1.

  (5) An organic semiconductor material comprising a compound represented by the following general formula (2).

(Wherein, L is represents a non-substituted methyl group, or is substituted with ethyl group or propyl group, or unsubstituted carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom or et linking group selected, R ₁ to R ₈ is a hydrogen atom, a halogen atom, or represents an unsubstituted methyl group, ethyl group or propyl group, the unsubstituted methyl group, ethyl group or propyl group substituting the L and the R ₁ The unsubstituted methyl group, ethyl group or propyl group constituting ˜R ₈ may be linked to each other , and Z represents an unsubstituted aromatic ring.)
(6) The organic semiconductor material as described in (5) above, wherein in the compound represented by the general formula (2), the aromatic ring represented by Z is an unsubstituted benzene ring.

  (7) An organic semiconductor film comprising the organic semiconductor material according to any one of (1) to (6).

  (8) An organic semiconductor formed by dissolving the organic semiconductor material according to any one of (1) to (6) above in an organic solvent, and applying and drying the obtained solution. film.

  (9) An organic semiconductor device using the organic semiconductor material according to any one of (1) to (6).

  (10) An organic thin film transistor using the organic semiconductor material according to any one of (1) to (6) for a semiconductor layer.

  According to the present invention, there are provided an organic semiconductor material that is manufactured by a simple process, has good characteristics as a transistor, and further suppresses deterioration over time, and an organic semiconductor film, an organic semiconductor device, and an organic thin film transistor using the organic semiconductor material. be able to.

  Regarding the above problems, the researchers of the present invention studied further improvements with reference to the above-mentioned known information. As a result, the acene compound substituted with a silylethynyl group is an acene-based compound substituted with an alkyl group, an aryl group, or the like. Compared to the compound, it was confirmed to have improved oxygen stability.

  As an effect obtained by substitution with a silylethynyl group, in Non-Patent Document 5, a large substituent such as a silylethynyl group is introduced at the peri-position of pentacene so that the aromatic ring in the crystal is “Face to Face”. It was said that when a crystal having only a structure was produced, a stable thin film was obtained only in the case of a substituent having a specific size that gave a stable crystal structure.

  Further, in Non-Patent Document 6, “the introduction of the silylethynyl group has made it possible to deepen the HOMO level by 300 mV or more with respect to the unsubstituted aromatic ring, so that stability against oxidation has not been obtained. "". Further, as described in Non-Patent Document 7, it is known that substitution of a pentacene mother nucleus with an electron-withdrawing group increases the redox potential and imparts oxidation stability.

  Thus, in order to improve the stability of an acene compound such as pentacene against oxidation, it is presumed that not only electronic factors but also three-dimensional factors are involved.

  Based on such knowledge, the researchers of the present invention use a structure having a ring structure in place of the end of the ethynyl group with a linear alkyl group, a branched alkyl group, or an alkylsilyl group having a similar structure. It was thought that a film with higher crystallinity could be obtained. This is apparent from the fact that even organic compounds having the same size and molecular weight change the melting point (crystallinity), boiling point, and density (intermolecular force) depending on the structure. As an example, a comparison table of the melting point, boiling point, and density of the C6 compound and its analogs is given below.

  In the organic semiconductor material of the present invention, an organic semiconductor material useful for thin film transistor applications can be obtained by using a compound having a structure defined in any one of claims 1 to 6. In addition, the organic semiconductor film, organic semiconductor device, and organic thin film transistor (hereinafter also referred to as organic TFT) of the present invention produced using the organic semiconductor material have high carrier mobility and good ON / OFF characteristics. It has been found that the transistor has excellent durability and high durability.

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

[Organic semiconductor materials]
The organic semiconductor material of the present invention is an organic semiconductor material having a structure in which an acene mother nucleus is connected to a cyclic structure by an ethynyl group as represented by the general formula (1).

In the general formula (1), Y ₁ and Y ₂ represent an alicyclic structure selected from a substituted or unsubstituted cycloalkyl ring, cycloalkenyl ring, and heterocyclic ring, and Z represents a substituted or unsubstituted aromatic ring. . n represents an integer of 0 or 1.

The effect of the ethynyl group is to reduce the redox potential of the acene mother nucleus to a level stable against oxidation, and the sterically large substituents Y ₁ and Y ₂ can be substituted with the “Face to The “Face” packing structure has two effects of moving away to a position that does not hinder the packing structure. Further, the cyclic structures Y ₁ and Y ₂ that are the characteristics of the general formula (1) can further increase the crystallinity of the coating film, and as a result, not only can the mobility of the coating film be increased. It is presumed that the thin film is difficult to permeate deterioration factors such as oxygen and moisture and the durability can be improved.

  Examples of the cyclic structure include aromatic ring structures such as benzene, but aromatic rings may form a “Face to Edge” packing structure, resulting in a change in the makeup structure and movement of the coating film. The cyclic structure for substituting one end of the ethynyl group needs to be not an aromatic ring because the degree of the reaction may decrease or the stability against oxidation may decrease.

Examples of such a cyclic structure represented by Y ₁ and Y ₂ in the general formula (1) include a hydrocarbon-based cyclic structure such as a cyclopropane ring, a cyclopropene ring, a cyclopropanone ring, a cyclobutane ring, and a cyclobutene. Ring, cyclobutanone ring, cyclopentane ring, cyclopentene ring, cyclopentadiene ring, cyclopentanone ring, cyclohexane ring, cyclohexene ring, cyclohexadiene ring, cyclohexanone ring, cyclohexanedione ring, cyclooctane ring, cyclooctadiene ring, norbornane ring , Norbornene ring, camphor ring, decalin ring, cubane ring, bicyclo [2,2,2] -octane ring, adamantane ring and the like.

  As the heterocyclic structure, epoxy group, aziridine ring, thiirane ring, oxetane ring, azetidine ring, thietane ring, tetrahydrofuran ring, dioxolane ring, pyrrolidine ring, pyrazolidine ring, imidazolidine ring, oxazolidine ring, tetrahydrothiophene ring, sulfolane ring, Thiazolidine ring, ε-caprolactone ring, ε-caprolactam ring, piperidine ring, hexahydropyridazine ring, hexahydropyrimidine ring, piperazine ring, morpholine ring, tetrahydropyran ring, 1,3-dioxane ring, 1,4-dioxane ring, Examples include trioxane ring, tetrahydrothiopyran ring, thiomorpholine ring, thiomorpholine-1,1-dioxide ring, pyranose ring, diazabicyclo [2,2,2] -octane ring.

  Further, a ring structure in which a part of the ring structure is replaced with oxygen, nitrogen, silicon, phosphorus, sulfur, or the like may be used. Moreover, you may have a substituent as mentioned later in a part of ring structure.

  The acene mother nucleus connected to the cyclic structure by an ethynyl group represents a condensed aromatic ring in which four rings are condensed when n = 0 in the general formula (1), and when n = 1 Represents a condensed aromatic ring in which five rings are condensed. When the number of condensed rings in the acene-based mother nucleus is less than 4, it is difficult to obtain good mobility, and when it is 6 or more rings, it is difficult to ensure stability against oxidation.

  Examples of such acene-based nuclei include tetracene, naphthoindole, anthrafuran, anthrathiophene, naphthoquinoline, naphthoisoquinoline, naphthoquinoxaline, naphthophthalazine, naphthoquinazoline, pentacene, pyrrolonaphthacene, thienonaphthacene, anthradithiophene, anthradithiophene, Examples include 1-azapentacene, 1,8-diazapentacene, 2,9-diazapentacene, hexacene, dibenzopentacene, hexacene, dithienopentacene and the like. These acene-based nuclei may have a substituent as described later.

  Examples of the substituent that replaces the acene mother nucleus and the cyclic structure include a substituted or unsubstituted alkyl group, alkenyl group, alkynyl group, cycloalkyl group, aryl group, heteroaryl group, and heterocyclic group. It is done. These may be connected to each other to form a ring.

  Examples of the alkyl group include a cycloalkyl group such as a methyl group, an ethyl group, a propyl group, an isopropyl group, a tert-butyl group, a neopentyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group, a tetradecyl group, and a pentadecyl group. Are the above-mentioned cyclopentyl group, cyclohexyl group, etc., alkenyl groups are, for example, vinyl groups, allyl groups, etc., and alkynyl groups are, for example, ethynyl groups, propargyl groups, diethynyl groups, etc., aryl groups (aromatic carbocyclic groups) As an aromatic hydrocarbon group), for example, phenyl group, p-chlorophenyl group, tolyl group, xylyl group, mesityl group, biphenylyl group, naphthalene ring, anthracene ring, azulene ring, acenaphthene ring, fluorene Ring, phenanthrene ring, indene ring, pyrene ring, te Helene ring, pentacene ring, hexacene ring, benzopyrene ring, benzoazulene ring, chrysene ring, benzochrysene ring, acenaphthene ring, acenaphthylene ring, triphenylene ring, coronene ring, benzocoronene ring, hexabenzocoronene ring, benzofluorene ring, fluoranthene ring, perylene A part of hydrogen of a condensed aromatic hydrocarbon ring such as a ring, a naphthoperylene ring, a pentabenzoperylene ring, a benzoperylene ring, a pentaphen ring, a picene ring, a pyrene ring, a coronene ring, a naphtho coronene ring, an ovarene ring and an anthraanthrene ring. Examples of the substituted aryl group heteroaryl group (also referred to as aromatic heterocyclic group) include, for example, a pyridine ring, pyridazine ring, pyrimidine ring, pyrazine ring, triazine ring, tetrazine ring, quinoline ring, isoquinoline ring, acridine ring, F Nantridine ring, quinoxaline ring, cinnoline ring, phthalazine ring, quinazoline ring, naphthyridine ring, pteridine ring, phenazine ring, phenanthroline ring, pyrrole ring, pyrazole ring, imidazole ring, triazole ring, indole ring, benzimidazole ring, carbazole ring, purine Ring, pyrrolopyrrole ring, pyrazolotriazole ring, benzoquinoline ring, carbazole ring, azacarbazole ring, phenazine ring, phenanthridine ring, phenanthroline ring, carboline ring, cyclazine ring, kindrin ring, tepenidine ring, quinindrine ring, triphenodi Thiazine ring, triphenodioxazine ring, phenanthrazine ring, anthrazine ring, perimidine ring, diazacarbazole ring (any one of the carbon atoms constituting the carboline ring is replaced by a nitrogen atom) Phenanthroline ring, furan ring, benzofuran ring, isobenzofuran ring, dibenzofuran ring, oxazole ring, isoxazole ring, oxadiazole ring, furazane ring, thiophene ring, benzothiophene ring, thieno [2,3 -A] thiophene ring, thieno [2,3-b] thiophene ring, anthradithiophene ring, dithiafulvene ring, thiazole ring, benzothiazole ring, dibenzothiophene ring, benzodithiophene ring, anthradithiophene ring, thiothiophene ring, etc. Examples of the heterocyclic group such as a substituent in which a part of hydrogen of the condensed aromatic hydrocarbon ring is replaced include the aforementioned pyrrolidyl group, imidazolidyl group, morpholyl group, oxazolidyl group, piperidinyl group, piperazinyl group and the like.

  In addition to the above substituents, alkoxy groups (for example, methoxy group, ethoxy group, propyloxy group, pentyloxy group, hexyloxy group, octyloxy group, dodecyloxy group, etc.), cycloalkoxy groups (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.), A cycloalkylthio group (eg, cyclopentylthio group, cyclohexylthio group, etc.), an arylthio group (eg, phenylthio group, naphthylthio group, etc.), an alkoxycarbonyl group (eg, methyloxycarbonyl group, ethyloxycarbonyl group, butyrate) Oxycarbonyl group, octyloxycarbonyl group, dodecyloxycarbonyl group, etc.), aryloxycarbonyl group (eg, phenyloxycarbonyl group, naphthyloxycarbonyl group, etc.), sulfamoyl group (eg, aminosulfonyl group, methylaminosulfonyl group, dimethyl) Aminosulfonyl 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-ethyl Hexylcarbonyl group, dodecylcarbonyl group, phenylcarbonyl group, naphthylcarbonyl group, pyridylcarbonyl group, etc.), acyloxy group (for example, acetyloxy group, ethylcarbonyloxy 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 group, phenylcarbonylamino group, naphthylcarbonylamino group, etc.), carbamoyl group (for example, amino Nocarbonyl group, methylaminocarbonyl group, dimethylaminocarbonyl group, propylaminocarbonyl group, pentylaminocarbonyl group, cyclohexylaminocarbonyl group, octylaminocarbonyl group, 2-ethylhexylaminocarbonyl group, dodecylaminocarbonyl 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, phenylureido group, naphthylureido group) , 2-pyridylaminoureido 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, etc.), 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, nitro group, hydroxy group, mercapto group, alkylsilyl group (for example, trimethylsilyl group, triisopropylsilyl group, triphenylsilyl group, phenyldiethyl) Silyl group, etc.), alkoxysilyl group (eg, trimethoxysilyl group, triethoxysilyl group, silatrane group, etc.), sulfinyl group (eg, methylsulfinyl group, ethylsulfinyl group, butylsulfinyl group, cyclohexylsulfinyl group, 2-ethyl) Ruhexylsulfinyl 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) Group, dodecylsulfonyl group, etc.), arylsulfonyl group or heteroarylsulfonyl group (eg, phenylsulfonyl group, naphthylsulfonyl group, 2-pyridylsulfonyl group, etc.), disulfide group, sulfoxide group, sulfone group, sulfoximine group, oxo group ( = O), a thione group (= S), a phosphate ester group (eg, dihexyl phosphoryl group), a thiophosphate ester group, a phosphorylamino group, a phosphite ester group (eg, Diphenylphosphinyl 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.

  By the way, the organic semiconductor material is preferably crystalline as described above. When the coating film becomes a crystal, the arrangement of the compounds is adjusted, and a thin film with higher mobility can be obtained. In addition, there is an effect that deterioration factors such as oxygen and moisture are less likely to penetrate into the thin film, and deterioration is less likely to occur.

Since compounds having higher symmetry tend to have higher crystallinity, among the compounds represented by the general formula (1), there are compounds having Y ₁ = Y ₂ and n = 1 (5-ring condensed acene mother nucleus). preferable. This is because such a structure can provide a point-symmetric structure or a line-symmetric structure.

Moreover, it is preferable that both of the substituents Y ₁ and Y ₂ in the cyclic structure are heterocyclic groups. This is because the heterocyclic ring structure has a stronger intermolecular force than the hydrocarbon ring structure and tends to form a more stable crystal structure.

In addition, it is known that acene-based nuclei are generally oxidized by singlet oxygen, but cyclic structures having atoms such as nitrogen, oxygen, and sulfur may function as singlet oxygen quenchers, When the substituents Y ₁ and Y _{2 in the} structure have a heterocyclic structure, singlet oxygen can be deactivated before reacting with the acene-based nucleus, and deterioration of the performance of the organic semiconductor film can be prevented. Examples of the singlet oxygen quencher include compounds SQ1 to SQ9 described on pages 38 to 39 of JP-A-11-288066.

  Among these compounds having a heterocyclic structure, a compound having a structure represented by the general formula (2) is more preferable.

In General Formula (2), L represents a linking group selected from a substituted or unsubstituted carbon atom, nitrogen atom, oxygen atom, sulfur atom, and a single bond, and R _{1 to} R ₈ are a hydrogen atom, a halogen atom, or It represents a substituted or unsubstituted alkyl group and may be linked to each other. Z represents a substituted or unsubstituted aromatic ring.

  By adopting such a structure, structures such as N-alkylpiperidine, N, N′-dialkylpiperazine, thiomorpholine ring, thiomorpholine-1,1-dioxide ring which are one of typical singlet oxygen quenchers In the molecule, the stability to oxygen can be further improved. In addition, it is possible to obtain a thin film having high mobility and high crystallinity because the substituent is appropriately sterically sized. Among these, a compound in which the aromatic ring represented by Z is an unsubstituted benzene ring and the acene-based mother nucleus is pentacene is preferable. With such a structure, the compound has high symmetry and excellent crystallinity, and the coating film of these compounds can achieve both excellent mobility and oxidation stability.

  The molecular weight of the compound represented by the general formula (1) or (2) is preferably in the range of 300 to 5,000. By setting the molecular weight to 300 or more, the volatility of the compound can be sufficiently lowered, and volatilization during production and process contamination can be prevented. Moreover, the solubility to a solvent can be kept in a favorable range by setting it as 5000 or less. Moreover, the stacking property between molecules can be made good, and the TFT performance can be made good. The molecular weight is more preferably in the range of 500 to 2000. The molecular weight of the organic semiconductor material of the present invention can be measured with a mass spectrometer or the like.

  Hereinafter, although the specific example of a compound represented by General formula (1) and (2) based on this invention is shown, this invention is not limited to these.

  The above compounds can be synthesized with reference to the following documents. Synthesis of ethynyl alicyclic compounds is described, for example, in J. Org. Org. Chem. , Vol. 56 (1991), p1500. Synthesis of ethynyl heterocyclic compounds is described, for example, in J. Org. Am. Chem. Soc. , Vol. 124 (2002), p2456, supporting information. The addition reaction to the acene mother nucleus is described, for example, in J. Org. Am. Chem. Soc. , Vol. 123 (2001), p9482, supporting information.

[Organic semiconductor film, organic semiconductor device, organic thin film transistor]
The organic semiconductor film, organic semiconductor device, and organic thin film transistor of the present invention will be described.

  When the organic semiconductor material of the present invention is used for a semiconductor layer of an organic semiconductor film, an organic semiconductor device, or an organic thin film transistor, an organic semiconductor device and an organic thin film transistor that are driven well can be provided. An organic thin film transistor has a top gate type having a source electrode and a drain electrode connected by an organic semiconductor as a semiconductor layer on a support, and having a gate electrode on the support via a gate insulating layer, and a gate on the support. It is roughly classified into a bottom gate type having an electrode and having a source electrode and a drain electrode connected by an organic semiconductor through a gate insulating layer.

  In order to install the organic semiconductor material of the present invention on a semiconductor layer of an organic semiconductor film, an organic semiconductor device, or an organic thin film transistor, it can be installed on a substrate by vacuum deposition, but it can be dissolved in an appropriate solvent and added as necessary. It is preferable to place the solution prepared by adding the solution on the substrate by cast coating, spin coating, printing, inkjet method, 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, but specifically, diethyl ether or diisopropyl ether. Linear 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, nitrobenzene And aromatic solvents such as m-cresol, N-methylpyrrolidone, carbon disulfide and the like. Of these solvents, a solvent containing a non-halogen solvent is preferable, and a non-halogen solvent is preferable.

  In the organic thin film transistor of the present invention, the organic semiconductor material of the present invention is preferably used for the semiconductor layer as described above. The semiconductor layer is preferably formed by applying a solution or dispersion containing these organic semiconductor materials. The solvent for dissolving the organic semiconductor material is preferably a solvent containing the non-halogen solvent, and is preferably composed of a non-halogen solvent.

  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, 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 of forming an electrode, a method of forming an electrode using a known photolithographic method or a lift-off method with a conductive thin film formed using a method such as vapor deposition or sputtering using the above as a raw material, on 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, laser ablation, or the like. 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 trioxide yttrium. 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 the like, spraying Examples include a wet process such as a coating method, a spin coating method, a blade coating method, a dip coating method, a casting method, a roll coating method, a bar coating method, a coating method such as a die coating method, and a patterning method such as printing or inkjet. Can be used depending on the material.

  The wet process is a method of applying and drying a liquid in which inorganic oxide fine particles 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 an alkoxide solution 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 Nos. 11-61406, 11-133205, 2000-121804, 2000-147209, 2000-185362, and the like. Accordingly, a highly functional thin film can be formed with high productivity.

  In addition, as an organic compound film, polyimide, polyamide, polyester, polyacrylate, photo-curing polymer of photo radical polymerization system, photo cation polymerization system, or copolymer containing acrylonitrile component, polyvinyl phenol, polyvinyl alcohol, novolac resin, and Cyanoethyl pullulan or the like can also 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 triacetyl cellulose (TAC), diacetyl cellulose (DAC), 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 organic thin-film transistor using the organic-semiconductor film formed using the organic-semiconductor material of this invention is demonstrated.

  FIG. 1 is a diagram showing a configuration example of an organic thin film transistor of 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 both electrodes, and insulation is formed thereon. The layer 5 is formed, and the gate electrode 4 is further formed thereon to form an organic thin film 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 thereon, and the source electrode 2 and the drain electrode 3 are formed on the metal foil or the like. An organic semiconductor layer 1 formed 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 thin film transistor sheet.

  The organic thin film transistor sheet 10 has a large number of organic thin film transistors 11 arranged in a matrix. 7 is a gate bus line of each organic thin film transistor 11, and 8 is a source bus line of each organic thin film transistor 11. An output element 12 is connected to the source electrode of each organic thin film transistor 11, and the 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.

As the performance of the organic thin film transistor, the required performance varies depending on its application. For example, in applications such as electronic paper, the carrier mobility is in the range of 0.01 to 1.0 cm ² / Vsec. The ON / OFF ratio is preferably in the range of 1.0 × 10 ^{5 to} 1.0 × 10 ⁷ . By setting it as such a range, a display can be driven at sufficient speed and a favorable gradation can be provided to a display.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.

<< Production of Organic Thin Film Transistor 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.

  On the Si wafer subjected to such surface treatment, Comparative Compound 1 (pentacene, manufactured by Aldrich Corporation, used after purification by sublimation of a commercially available reagent) was added to toluene which was bubbled with nitrogen for 30 minutes in a nitrogen atmosphere. Dissolved at a concentration of 5% by mass, spin-coated under a nitrogen atmosphere (rotation speed: 2500 rpm, 15 seconds), naturally dried to form a cast film, and then subjected to heat treatment at 50 ° C. for 30 minutes in a nitrogen atmosphere. gave.

  Further, gold was deposited on the surface of this film using a mask to form a source electrode and a drain electrode. An organic thin film transistor 1 having a source electrode and a drain electrode 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 produced.

<< Production of Organic Thin Film Transistor 2 >>
Comparative compound 2 (2,3,9,10-tetrahexylpentacene) is described in Organic Letters, vol. 2 (2000), p85.

  An organic thin film transistor 2 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 2.

<< Production of Organic Thin Film Transistor 3 >>
Comparative compound 3 is described in J. Org. Am. Chem. Soc. , Vol. 123 (2001), p9482, supporting information.

  An organic thin film transistor 4 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 4.

<< Production of Organic Thin Film Transistor 4 >>
Comparative compound 4 was synthesized by the method described in Non-Patent Document 6, supporting information.

  An organic thin film transistor 5 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 5.

<< Production of Organic Thin Film Transistor 5 >>
Comparative compound 5 is described in J. Org. Org. Chem. , Vol. 34 (1969), p1734.

  An organic thin film transistor 5 was produced in the same manner as in the production of the organic thin film transistor 1, except that the comparative compound 1 was changed to the comparative compound 5.

<< Production of Organic Thin Film Transistors 6-11 >>
Organic thin-film transistors 6 to 11 were produced in the same manner except that the organic semiconductor material of the present invention described in Table 1 was used instead of the comparative compound 1 in the production of the organic thin-film transistor 1.

<< Evaluation of carrier mobility and ON / OFF value >>
About the obtained organic thin-film transistors 1-14, the carrier mobility and ON / OFF value of each element were measured immediately after element preparation. In the present invention, the carrier mobility is obtained from the saturation region of the IV characteristic, and the ON / OFF ratio is obtained from the ratio of the drain current value when the drain bias is −50 V and the gate bias is −50 V and 0 V.

  Moreover, after putting each element into the environmental chamber of 40 degreeC90% RH for 48 hours for the same evaluation, the carrier mobility and the ON / OFF ratio were measured again. The obtained results are shown in Table 2.

  From the results of Table 2, Comparative Compound 1 has low solubility, and a film cannot be formed by coating, and organic thin film transistor 1 could not be confirmed to be driven as an organic semiconductor.

Comparative compound 2 has improved solubility as compared with comparative compound 1, and organic thin film transistor 2 has been confirmed to be driven as an organic semiconductor. However, the ON / OFF ratio is relatively low at 10 ³ units and is durable. It can be seen that the material is greatly deteriorated in performance after the test.

Organic thin-film transistors 3 and 4 showed sufficient TFT performance immediately after coating, but the mobility was 10 ⁻³ units and the ON / OFF ratio was 10 ⁴ units after the durability test, and the display could be driven. The value is not retained. In addition, in the organic thin film transistor 5 using the comparative compound 5 having an acene structure substituted with a phenylethynyl group, a thin film with high mobility could not be obtained.

On the other hand, the organic thin film transistors 6 to 11 manufactured using the organic semiconductor material of the present invention exhibit excellent characteristics in both carrier mobility and ON / OFF ratio immediately after manufacturing, and the mobility is 10 ⁻² even after the durability test. It can be seen that it has a high durability with little deterioration with time and an ON / OFF ratio of 10 ⁵ or more.

Among the organic semiconductor elements of the present invention, the organic TFT elements 9 and 10 using a compound in which the substituent for substituting the ethynyl group is a piperidine ring retains a mobility of 10 ⁻¹ even after the durability test. It was confirmed that the organic semiconductor element had good semiconductor performance and durability.

Example 2
<< Production of organic EL element >>
The organic EL device was produced by referring to the method described in Nature, Vol. 395, pages 151 to 154, and producing a top emission type organic EL device having a sealing structure as shown in FIG. 3, 101 denotes a substrate, 102a denotes an anode, 102b denotes an organic EL layer (specifically, an electron transport layer, a light emitting layer, a hole transport layer, and the like), 102c denotes a cathode, and the anode 102a The light emitting element 102 is formed by the organic EL layer 102b and the cathode 102c. Reference numeral 103 denotes a sealing film. The organic EL element of the present invention may be either a bottom emission type or a top emission type.

  The organic EL element of the present invention and the organic thin film transistor of the present invention (herein, the organic thin film transistor of the present invention is used as a switching transistor, a driving transistor, etc.) were produced to produce an active matrix light emitting element. For example, as shown in FIG. 4, a mode in which a substrate in which a TFT 602 (or an organic thin film transistor 602 may be formed) is formed on a glass substrate 601 is used as an example. Here, a known TFT manufacturing method can be referred to for the TFT 602 manufacturing method. Of course, the TFT may be a conventionally known top gate TFT or bottom gate TFT.

  The organic EL device produced above showed good light emission characteristics in various light emission forms such as single color, full color, and white.

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. It is a schematic diagram which shows an example of the organic EL element which has a sealing structure. It is a schematic diagram which shows an example of the board | substrate which has TFT used for an organic EL element.

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 thin-film transistor sheet 11 Organic thin-film transistor 12 Output element 13 Storage capacitor 14 Vertical drive circuit 15 Horizontal drive circuit 101, 201 substrate 102 organic EL element 102a, 202 anode 102b organic EL layer 102c, 204 cathode 103 sealing film 205 driving element 206 hole transport layer 207 light emitting layer 208 electron transport layer 601 substrate 602 TFT

Claims (10)

An organic semiconductor material comprising a compound represented by the following general formula (1):

(In the formula, Y ₁ and Y ₂ are each substituted with an unsubstituted methyl group, ethyl group or propyl group which may be linked to each other , or from an unsubstituted cycloalkyl ring, cycloalkenyl ring or heterocyclic ring. Represents an alicyclic 5-membered or 6-membered structure selected, Z represents an unsubstituted aromatic ring, and n represents an integer of 0 or 1.) _2. The organic semiconductor material according to claim 1, wherein in the compound represented by the general formula (1), Y ₁ = Y ₂ and n = 1. 3. The organic semiconductor material according to claim 1, wherein in the compound represented by the general formula (1), Y ₁ and Y ₂ are both heterocyclic rings.   The organic semiconductor material according to any one of claims 1 to 3, wherein in the compound represented by the general formula (1), the aromatic ring represented by Z is an unsubstituted benzene ring. . An organic semiconductor material comprising a compound represented by the following general formula (2):

(Wherein, L is represents a non-substituted methyl group, or is substituted with ethyl group or propyl group, or unsubstituted carbon atom, a nitrogen atom, an oxygen atom, a sulfur atom or et linking group selected, R ₁ to R ₈ is a hydrogen atom, a halogen atom, or represents an unsubstituted methyl group, ethyl group or propyl group, the unsubstituted methyl group, ethyl group or propyl group substituting the L and the R ₁ The unsubstituted methyl group, ethyl group or propyl group constituting ˜R ₈ may be linked to each other , and Z represents an unsubstituted aromatic ring.)   6. The organic semiconductor material according to claim 5, wherein in the compound represented by the general formula (2), the aromatic ring represented by Z is an unsubstituted benzene ring.   The organic-semiconductor film of any one of Claims 1-6 is contained, The organic-semiconductor film characterized by the above-mentioned.   It forms by melt | dissolving the organic-semiconductor material of any one of Claims 1-6 in an organic solvent, apply | coating and drying the obtained solution, The organic-semiconductor film characterized by the above-mentioned.   The organic-semiconductor device using the organic-semiconductor material of any one of Claims 1-6.   An organic thin film transistor using the organic semiconductor material according to claim 1 for a semiconductor layer.

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