JP2012206953A - Dithienobenzodithiophene derivative, and organic thin-film transistor using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new dithienobenzodithiophene derivative having excellent solubility in solvents, thereby allowing easy development into an organic semiconductor material, etc., and expectation of high carrier mobility, and to provide an organic thin-film transistor using the same.SOLUTION: There is provided the dithienobenzodithiophene derivative represented by general formula(1) (wherein, substituents Rand Rare the same or different, and represent each a substituent selected from the group consisting of n-heptyl, n-octyl, 10C alkyl, 12C alkyl and 14C alkyl).

Description

  The present invention relates to a dithienobenzodithiophene derivative that can be developed into an electronic material such as an organic semiconductor material, and an organic thin film transistor using the same. In particular, the organic semiconductor material can be easily used because of its excellent solubility in a solvent. The present invention relates to a novel dithienobenzodithiophene derivative that can be developed into a thin film and the like, and an organic thin film transistor using the same.

  Organic semiconductor devices typified by organic thin film transistors have been attracting attention in recent years because they have features not found in inorganic semiconductor devices such as energy saving, low cost, and flexibility. This organic semiconductor device is composed of several kinds of materials such as an organic semiconductor layer, a substrate, an insulating layer, and an electrode. Among them, the organic semiconductor layer responsible for charge carrier movement has a central role of the device. And since organic-semiconductor device performance is influenced by the carrier mobility of the organic material which comprises this organic-semiconductor layer, the appearance of the organic material which gives a high carrier mobility is desired.

  In addition, as a method for producing the organic semiconductor layer, a method such as a vacuum deposition method in which an organic material is vaporized under a high temperature vacuum, a coating method in which an organic material is dissolved in an appropriate solvent, and a solution thereof is applied is generally used. Known. In the coating method, the coating can be performed using a printing technique without using a high temperature and high vacuum condition. Therefore, the coating method is an economically preferable process because it can greatly reduce the manufacturing cost of device fabrication by printing. And the organic-semiconductor material used for such an application | coating method has a low molecular type and a high molecular type, and it is preferable that it has a solubility of 1.0 weight% or more. In general, a low molecular weight material having a high carrier mobility is preferable, but the types of low molecular weight organic semiconductor materials that have a solubility of 1.0% by weight or more and provide high mobility are extremely limited. Currently.

  Examples of the low molecular weight material include bis ((triisopropylsilyl) ethynyl) pentacene (see, for example, Non-Patent Document 1) and dialkyl-substituted benzothienobenzothiophene (highly soluble in nonpolar solvents such as hexane). For example, refer to Patent Document 1), dihexyl dithienobenzodithiophene (for example, refer to Patent Document 2), and the like.

Re-published patent WO2008 / 047896 (see, for example, the claims) WO 2010/000670 (see, for example, claims)

Applied Physics Letters (USA), 2007, Vol. 91, 06354-1 to 063514-3

However, bis ((triisopropylsilyl) ethynyl) pentacene described in Non-Patent Document 1 shows high solubility in nonpolar solvents such as hexane, but the mobility is 0.05 to 1.8 cm ² / Vs. The problem was that it fluctuated greatly depending on the film forming conditions. In addition, the dialkyl-substituted benzothienobenzothiophene described in Patent Document 1 can achieve a mobility of 1.0 cm ² / Vs or more by heat treatment at 100 ° C. or more as a spin coat film. When not applied, the temperature was as low as 0.08 to 0.17 cm ² / Vs, the melting point was as low as 120 to 130 ° C., and there was a problem in heat resistance. The dihexyl dithienobenzodithiophene proposed in Patent Document 2 shows a mobility of 0.112 cm ² / Vs by a drop cast method, but has a problem in solubility in a solvent at room temperature.

In order to drive a display such as organic electroluminescence, the transistor needs to have a mobility of at least 0.5 cm ² / Vs. However, the transistor stably gives a high mobility without heat treatment and is 1. An organic semiconductor material having a solubility of 0% by weight or more is not known, and the appearance of such an organic semiconductor material is desired.

  Accordingly, an object of the present invention is to provide a novel organic semiconductor material that can be easily developed into an organic semiconductor material or the like because of its excellent solubility in a solvent.

  As a result of intensive studies to solve the above problems, the present inventors have found that a novel dithienobenzodithiophene derivative gives high carrier mobility and exhibits excellent solubility in a solvent. It came to completion.

  That is, the present invention relates to a dithienobenzodithiophene derivative represented by the following general formula (1) and an organic thin film transistor using the same.

（ここで、置換基Ｒ^１及びＲ^２は同一又は異なって、ｎ−ヘプチル基、ｎ−オクチル基、炭素数１０のアルキル基、炭素数１２のアルキル基及び炭素数１４のアルキル基からなる群より選択される置換基を示す。）
以下に本発明を詳細に説明する。

(Wherein, the substituents R ¹ and R ² are the same or different and are composed of an n-heptyl group, an n-octyl group, an alkyl group having 10 carbon atoms, an alkyl group having 12 carbon atoms, and an alkyl group having 14 carbon atoms. The substituent selected from the above is shown.)
The present invention is described in detail below.

The dithienobenzodithiophene derivative of the present invention is a derivative represented by the above general formula (1), and the substituents R ¹ and R ² are the same or different, and are an n-heptyl group, an n-octyl group, a carbon number of 10 The substituent is selected from the group consisting of an alkyl group, an alkyl group having 12 carbon atoms, and an alkyl group having 14 carbon atoms. Here, when the substituents R ¹ and R ² are substituents other than an n-heptyl group, an n-octyl group, an alkyl group having 10 carbon atoms, an alkyl group having 12 carbon atoms, and an alkyl group having 14 carbon atoms, The dithienobenzodithiophene derivative has problems such as low solubility in a solvent and unsatisfactory carrier mobility.

Specific examples of the substituents R ¹ and R ² include, for example, an n-heptyl group, an n-octyl group; an alkyl group having 10 carbon atoms such as an n-decyl group, a methylnonyl group, a dimethyloctyl group, and an ethyloctyl group. An alkyl group having 12 carbon atoms such as n-dodecyl group, methylundecyl group, dimethyldecyl group and ethyldecyl group; an alkyl group having 14 carbon atoms such as n-tetradecyl group, methyltridecyl group, dimethyldodecyl group and ethyldodecyl group; Among them, since it becomes a dithienobenzodithiophene derivative that is particularly excellent in solubility in a solvent and gives high carrier mobility, an n-heptyl group, an n-octyl group, an n-decyl group, It is preferably an n-dodecyl group or an n-tetradecyl group.

  Specific examples of the dithienobenzodithiophene derivative of the present invention include the following.

そして、より好ましいものとしては、ジｎ−ヘプチルジチエノベンゾジチオフェン、ジｎ−オクチルジチエノベンゾジチオフェン、ジｎ−デシルジチエノベンゾジチオフェン、ジｎ−ドデシルジチエノベンゾジチオフェン、ジｎ−テトラデシルジチエノベンゾジチオフェン、等を挙げることができる。

More preferably, di-n-heptyldithienobenzodithiophene, di-n-octyldithienobenzodithiophene, di-n-decyldithienobenzodithiophene, di-n-dodecyldithienobenzodithiophene, din -Tetradecyl dithienobenzodithiophene, etc. can be mentioned.

The dithienobenzodithiophene derivative of the present invention is suitable for film formation by a drop cast method, particularly an ink jet method, and therefore preferably exhibits a solubility of 1% by weight or more with respect to a solvent at room temperature. Examples of the solvent used here include aromatic hydrocarbon solvents such as toluene, xylene, mesitylene, biphenyl, ethylbenzene, hexylbenzene, and octylbenzene; aliphatic hydrocarbon solvents such as hexane, heptane, octane, decane, dodecane, and tetradecane. Halogen compounds such as o-dichlorobenzene, chlorobenzene, trichlorobenzene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chloroform, dichloromethane; tetrahydrofuran (hereinafter referred to as THF), dioxane, etc. Ether solvent; acetic acid Ester solvents such as til and γ-butyrolactone; amide solvents such as N, N-dimethylformamide and N-methyl-2-pyrrolidone (hereinafter referred to as NMP); Since it can be obtained, an aromatic hydrocarbon solvent having 7 to 13 carbon atoms such as toluene, xylene, and ethylbenzene is preferable, and toluene and xylene are particularly preferable. Here, room temperature is generally referred to as room temperature, and examples thereof include a temperature of 20 to 28 ° C. The above-mentioned solvents and dithienobenzodithiophene represented by the general formula (1) A solution of the dithienobenzodithiophene derivative represented by the general formula (1) can be prepared by mixing the derivatives and heating and stirring. The temperature at the time of heating and stirring is preferably 30 to 150 ° C, particularly preferably 40 to 100 ° C. The concentration of the dithienobenzodithiophene derivative represented by the general formula (1) when stirring is preferably 0.1 to 10.0% by weight.

  As a method for producing the dithienobenzodithiophene derivative of the present invention, any production method can be used as long as the dithienobenzodithiophene derivative can be produced. Since it is possible to produce a dithienobenzodithiophene derivative, it is preferable to produce a dithienobenzodithiophene derivative by a production method through at least the following steps (A) to (D).

  Step (A): 1,4-di (3-bromothienyl) -2,5- with 3-bromothiophene-2-zinc derivative and 1,4-dibromo-2,5-difluorobenzene in the presence of a palladium catalyst. A process for producing difluorobenzene.

  Step (B): Dithienobenzodithiophene by intramolecular cyclization of 1,4-di (3-bromothienyl) -2,5-difluorobenzene obtained in Step (A) in the presence of an alkali metal sulfide. Manufacturing process.

  Step (C): A diacylate of dithienobenzodithiophene is produced by Friedel-Crafts acylation reaction of dithienobenzodithiophene obtained in step (B) and an acyl chloride compound in the presence of aluminum chloride as a catalyst. Process.

  (D) Process; The process of using the diacyl body of the dithienobenzodithiophene obtained by the (C) process for a reductive reaction, and manufacturing a dithienobenzodithiophene derivative.

  And the more specific manufacturing scheme of a preferable manufacturing method is shown below.

ここで、（Ａ）工程は、パラジウム触媒の存在下、３−ブロモチオフェン−２−亜鉛誘導体と１，４−ジブロモ−２，５−ジフルオロベンゼンのクロスカップリングにより１，４−ジ（３−ブロモチエニル）−２，５−ジフルオロベンゼンを製造する工程である。

Here, in the step (A), 1,4-di (3- (3) is obtained by cross-coupling of a 3-bromothiophene-2-zinc derivative and 1,4-dibromo-2,5-difluorobenzene in the presence of a palladium catalyst. This is a process for producing bromothienyl) -2,5-difluorobenzene.

  The 3-bromothiophene-2-zinc derivative is prepared by using an organometallic reagent such as isopropylmagnesium bromide, ethylmagnesium chloride, phenylmagnesium chloride, etc., replacing bromine at the 2-position of 2,3-dibromothiophene with magnesium halide, and then chlorinating. It can be prepared by exchanging metal with zinc. It is also possible to prepare a Grignard reagent of 2,3-dibromothiophene using magnesium metal instead of the organometallic reagent. The conditions for preparing the 2,3-dibromothiophene Grignard reagent can be carried out, for example, in a solvent such as THF or diethyl ether within a temperature range of -80 ° C to 70 ° C. A 3-bromothiophene-2-zinc derivative can be prepared by reacting the Grignard reagent solution with zinc chloride. Zinc chloride may be used as it is, or it may be THF or diethyl ether solution. As temperature, it can implement within the range of -80 degreeC-30 degreeC.

  1,4-di (3-bromothienyl)-by cross-coupling the prepared 3-bromothiophene-2-zinc derivative and 1,4-dibromo-2,5-difluorobenzene in the presence of a palladium catalyst. 2,5-difluorobenzene can be synthesized. In this case, examples of the palladium catalyst include tetrakis (triphenylphosphine) palladium, bis (triphenylphosphine) dichloropalladium, and the like. The reaction temperature is 20 to 80 ° C. it can.

  Step (B) is a step of producing dithienobenzodithiophene by intramolecular cyclization of 1,4-di (3-bromothienyl) -2,5-difluorobenzene in the presence of an alkali metal sulfide.

  Examples of the alkali metal sulfide include sodium sulfide, potassium sulfide, lithium sulfide, rubidium sulfide, and hydrates thereof. Examples of the intramolecular cyclization reaction include NMP, N, N-dimethylformamide, and the like. In the temperature range of 80 ° C. to 200 ° C.

  Step (C) is a step of producing a diacylate of dithienobenzodithiophene by Friedel-Crafts acylation reaction of dithienobenzodithiophene and an acyl chloride compound in the presence of aluminum chloride as a catalyst.

  Examples of the acyl chloride compound include heptanoyl chloride, octanoyl chloride, decanoyl chloride, dodecanoyl chloride, and tetradecanoyl chloride. The Friedel-Crafts acylation reaction can be carried out in a temperature range of 0 ° C. to 40 ° C. in a solvent such as dichloromethane, 1,2-dichloroethane, toluene and the like.

  Step (D) is a step of producing a dithienobenzodithiophene derivative by subjecting a diacyl derivative of dithienobenzodithiophene to a reduction reaction.

  The reduction reaction of dithienobenzodithiophene diacyl is, for example, using hydrazine as a reducing agent, in diethylene glycol, ethylene glycol or triethylene glycol in the presence of potassium hydroxide or sodium hydroxide at a temperature of 80 ° C. to 250 ° C. Can be done in a range. Further, for example, lithium aluminum hydride / aluminum chloride can be used as a reducing agent, and the reaction can be performed in a temperature range of −10 ° C. to 80 ° C. in a solvent of diethyl ether, diisopropyl ether, methyl tertiary butyl ether or THF.

  Furthermore, the produced dithienobenzodithiophene derivative can be purified by subjecting it to column chromatography and the like. As the separating agent, for example, silica gel, alumina, and as solvents, hexane, heptane, toluene, chloroform Etc.

  Further, the produced dithienobenzodithiophene derivative may be further purified by recrystallization, and the number of recrystallizations is preferably 2 to 5 times. Purity can be improved by increasing the number of recrystallizations. Examples of the solvent used for recrystallization include hexane, heptane, octane, toluene, xylene, chloroform, chlorobenzene, dichlorobenzene, and the like, and a mixture of any ratio thereof may be used. As the recrystallization method, a solution of a dithienobenzodithiophene derivative is prepared by heating (the concentration of the solution is preferably in the range of 0.01 to 10.0% by weight, and 0.05 to 5.0% by weight). The crystal of the dithienobenzodithiophene derivative is precipitated and isolated by cooling the solution, and the final cooling temperature during the isolation is in the range of −20 ° C. to 40 ° C. It is preferable that it exists in. In addition, when measuring purity, it can measure by analyzing by liquid chromatography.

  The dithienobenzodithiophene derivative of the present invention has excellent identification as an organic semiconductor material because it provides high carrier mobility, and has high solubility in a solvent, so it has a drop cast method, particularly an inkjet method, etc. By this method, an organic semiconductor layer can be formed easily and efficiently.

  The organic thin film transistor is obtained by laminating an organic semiconductor layer provided with a source electrode and a drain electrode on a substrate and a gate electrode through an insulating layer, and the dithienobenzo of the present invention is formed on the organic semiconductor layer. By using an organic semiconductor layer made of a dithiophene derivative, an organic thin film transistor can be obtained.

  FIG. 1 shows a structure of a general organic thin film transistor by a sectional shape. Here, (A) is a bottom gate-top contact type, (B) is a bottom gate-bottom contact type, (C) is a top gate-top contact type, and (D) is a top gate-bottom contact type. 1 is an organic semiconductor layer, 2 is a substrate, 3 is a gate electrode, 4 is a gate insulating layer, 5 is a source electrode, 6 is a drain electrode, and is composed of the dithienobenzodithiophene derivative of the present invention. The organic semiconductor layer can be applied to any organic thin film transistor.

  Examples of the substrate include polyethylene terephthalate, polyethylene naphthalate, polymethyl methacrylate, polymethyl acrylate, polyethylene, polypropylene, polystyrene, cyclic polyolefin, polyimide, polycarbonate, polyvinyl phenol, polyvinyl alcohol, poly (diisopropyl fumarate), poly ( (Diethyl fumarate), poly (diisopropyl maleate), polyethersulfone, polyphenylene sulfide, cellulose triacetate and other plastic substrates; glass, quartz, aluminum oxide, silicon, highly doped silicon, silicon oxide, tantalum dioxide, tantalum pentoxide, indium Inorganic material substrates such as tin oxide; Metal substrates such as gold, copper, chromium, titanium, aluminum, etc. Can. When highly doped silicon is used for the substrate, the substrate can also serve as the gate electrode.

  As the gate electrode, for example, aluminum, gold, silver, copper, highly doped silicon, tin oxide, indium oxide, indium tin oxide, chromium, titanium, tantalum, chromium, graphene, carbon nanotube and other inorganic materials; doped An organic material such as a conductive polymer (for example, PEDOT-PSS) can be given.

  Examples of the gate insulating layer include inorganic materials such as silicon oxide, silicon nitride, aluminum oxide, aluminum nitride, titanium oxide, tantalum dioxide, tantalum pentoxide, indium tin oxide, tin oxide, vanadium oxide, barium titanate, and bismuth titanate. Material substrate: Plastic materials such as polymethyl methacrylate, polymethyl acrylate, polyimide, polycarbonate, polyvinyl phenol, polyvinyl alcohol, poly (diisopropyl fumarate), poly (diethyl fumarate), polyethylene terephthalate, polyethylene naphthalate, polyethersulfone Can be mentioned. The surfaces of these gate insulating layers are, for example, octadecyltrichlorosilane, decyltrichlorosilane, decyltrimethoxysilane, octyltrichlorosilane, octadecyltrimethoxysilane, β-phenethyltrichlorosilane, β-phenethyltrimethoxysilane, phenyltrichlorosilane. Silanes such as phenyltrimethoxysilane; and those modified with silylamines such as hexamethyldisilazane can also be used. In general, the surface treatment of the gate insulating layer is preferable in order to increase the crystal grain size and molecular orientation of the organic semiconductor material, and to improve the carrier mobility and current on / off ratio, and to lower the threshold voltage. Results are obtained.

  As a material of the source electrode and the drain electrode, the same material as that of the gate electrode can be used, and the material may be the same as or different from the material of the gate electrode, or different materials may be stacked. In order to increase the carrier injection efficiency, surface treatment can be performed on these electrode materials. Examples thereof include benzene thiol and pentafluorobenzene thiol.

  When the organic semiconductor layer made of the dithienobenzodithiophene derivative of the present invention is used as the organic semiconductor layer, for example, a drop casting method such as spin coating, cast coating, or inkjet; blade coating; dip coating, screen printing, It is possible to use a method such as gravure printing, and among them, it is possible to easily and efficiently make an organic semiconductor layer, so that it is preferably a drop cast method such as spin coating, cast coating, inkjet, In particular, inkjet is preferable. Moreover, there is no restriction | limiting in the film thickness of the organic-semiconductor layer in that case, Preferably they are 1 nm-1 micrometer, Most preferably, they are 10 nm-300 nm.

  The organic semiconductor layer containing the dithienobenzodithiophene derivative of the present invention can be annealed at 40 to 150 ° C. after coating and drying.

  The dithienobenzodithiophene derivative of the present invention is used for organic semiconductor layers of transistors for electronic paper, organic EL displays, liquid crystal displays, IC tags (RFID tags), etc .; organic EL display materials; organic semiconductor laser materials; Battery materials; can be used for electronic materials such as photonic crystal materials.

  The novel dithienobenzodithiophene derivative of the present invention provides high carrier mobility and is excellent in solubility in a solvent, so that an organic semiconductor thin film can be easily produced, and a semiconductor represented by an organic thin film transistor The effect is extremely high as a device material.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

For the identification of the product, ¹ H-NMR spectrum and mass spectrum were used. The ¹ H-NMR spectrum was measured using JEOL GSX-270WB (270 MHz) manufactured by JEOL. Mass spectrum (MS) was measured by electron impact (EI) method (70 electron volts) using JEOL JMS-700 (trade name) manufactured by JEOL directly with the sample introduced.

  Confirmation of the progress of the reaction was performed by thin layer chromatography, gas chromatography (GC) and gas chromatography-mass spectrum (GCMS) analysis.

Gas chromatography analyzer; manufactured by Shimadzu Corporation (trade name) GC14B
Column; made by J & W Scientific, (trade name) DB-1, 30 m
Gas chromatography-mass spectrum analyzer; manufactured by PerkinElmer, (trade name) Auto System XL (MS unit: Turbomass Gold)
Column; J & W Scientific (trade name) DB-1, 30 m.

Liquid chromatographic analysis was used to determine the purity of the dithienobenzodithiophene derivative.
Device: manufactured by Tosoh (controller; PX-8020, pump; CCPM-II, degasser; SD-8022)
Column: manufactured by Tosoh (trade name) ODS-100V, 5 μm, 4.6 mm × 250 mm
Column temperature: 23 ° C
Eluent: dichloromethane: acetonitrile = 4: 6 (volume ratio)
Flow rate: 1.0 ml / min detector; UV (manufactured by Tosoh, (trade name) UV-8020, wavelength: 254 nm).

Example 1
(Synthesis of 1,4-di (3-bromothienyl) -2,5-difluorobenzene (step (A)))
Under a nitrogen atmosphere, 4.5 ml (3.6 mmol) of THF solution of isopropylmagnesium bromide (manufactured by Tokyo Chemical Industry Co., Ltd., 0.80M) and 10 ml of THF were added to a 100 ml Schlenk reaction vessel. The mixture was cooled to −75 ° C., and 873 mg (3.61 mmol) of 2,3-dibromothiophene (manufactured by Wako Pure Chemical Industries, Ltd.) was added dropwise. After aging at −75 ° C. for 30 minutes, 3.6 ml (3.6 mmol) of a diethyl ether solution of zinc chloride (manufactured by Sigma-Aldrich, 1.0 M) was added dropwise. After the temperature was gradually raised to room temperature, the produced white slurry was concentrated under reduced pressure, and 10 ml of light boiling was distilled off. To the obtained white slurry (3-bromothienyl-2-zinc chloride), 272 mg (1.00 mmol) of 1,4-dibromo-2,5-difluorobenzene (manufactured by Wako Pure Chemical Industries, Ltd.) and tetrakis (tri Phenylphosphine) palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) 39.1 mg (0.0338 mmol, 3.38 mol% with respect to 1,4-dibromo-2,5-difluorobenzene) and 10 ml of THF were added. After carrying out the reaction at 60 ° C. for 8 hours, the vessel was cooled with water and the reaction was stopped by adding 3 ml of 3N hydrochloric acid. Extraction was performed with toluene, and the organic phase was washed with brine and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the resulting residue was purified by silica gel column chromatography (hexane to hexane / dichloromethane = 10/1), recrystallized from hexane / toluene = 6/4, and 1,4-di (3- 227 mg of a light yellow solid of bromothienyl) -2,5-difluorobenzene was obtained (52% yield).
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 7.44 (d, J = 5.4 Hz, 2H), 7.39 (t, J = 7.8 Hz, 2H), 7.11 (d, J = 5.4 Hz, 2H).
MS m / z: 436 (M ^<+> , 100%), 276 (M ^<+ > ^- 2Br, 13).

(Synthesis of dithienobenzodithiophene (step (B)))
In a 100 ml Schlenk reaction vessel under a nitrogen atmosphere, 1,4-di (3-bromothienyl) -2,5-difluorobenzene 200 mg (0.458 mmol), NMP 10 ml, and sodium sulfide 9 hydrate (manufactured by Wako Pure Chemical Industries, Ltd.) ) 240 mg (1.00 mmol) was added. The resulting mixture was heated at 170 ° C. for 6 hours and the resulting reaction mixture was cooled to room temperature. After adding toluene and water, the phases were separated, and the organic phase was washed with water twice and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the resulting residue was washed twice with hexane to obtain 95 mg of a light yellow solid of dithienobenzodithiophene (yield 69%).
¹ H-NMR (CDCl ₃ , 60 ° C.): δ = 8.28 (s, 2H), 7.51 (d, J = 5.2 Hz, 2H), 7.30 (d, J = 5.2 Hz, 2H).
MS m / z: 302 (M ^<+> , 100%), 270 (M ^<+> -S, 5), 151 (M ^<+ > / 2, 10).

(Synthesis of di-n-octanoyldithienobenzodithiophene (step (C)))
To a 100 ml Schlenk reaction vessel were added 86.8 mg (0.286 mmol) of dithienobenzodithiophene and 14 ml of dichloromethane. This mixture was ice-cooled, and 134 mg (1.00 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries) and 140 mg (0.858 mmol) of octanoyl chloride (manufactured by Wako Pure Chemical Industries) were added. The resulting mixture was stirred at room temperature for 30 hours, then ice-cooled and water was added to stop the reaction. Toluene was added to the resulting slurry mixture for phase separation. The organic phase of the yellow slurry was washed with water and concentrated under reduced pressure. The obtained residue was washed with hexane / toluene = 1/1 and methanol and dried under reduced pressure to obtain 137 mg of di-n-octanoyldithienobenzodithiophene yellow solid (yield 86%).
¹ H-NMR (heavy benzene, 80 ° C.): δ = 7.73 (s, 2H), 7.26 (s, 2H), 2.58 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 16H), 0.86 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 554 (M}} +, 100%), 470 (M + -C 6 H 13 +1,43), 455 (M + -C 7 H 15, 15).

(Synthesis of di-n-octyldithienobenzodithiophene (step (D)))
In a 100 ml Schlenk reaction vessel, di n-octanoyldithienobenzodithiophene 108 mg (0.194 mmol), potassium hydroxide 223 mg (3.97 mmol), diethylene glycol 12 ml, and hydrazine monohydrate (manufactured by Wako Pure Chemical Industries) 412 mg (8.23 mmol) was added, and the mixture was stirred at 120 ° C for 1 hour, and further stirred at 230 ° C for 30 hours. After cooling to room temperature, toluene and water were added, and after phase separation, washing of the organic phase with water was repeated three times. The organic phase was dried over anhydrous sodium sulfate and concentrated under reduced pressure. The obtained residue was purified by silica gel column chromatography (hexane / toluene = 10/1, volume ratio) and recrystallized and purified once from hexane (pure grade manufactured by Wako Pure Chemical Industries, Ltd.). Furthermore, recrystallized and purified twice from hexane / toluene (both Wako Pure Chemical Industries pure grade) = 10/1 (volume ratio) and twice from chloroform, and white scaly crystals of di-n-octyldithienobenzodithiophene. 21 mg was obtained (yield 21%). In hexane / toluene = 10/1 recrystallization, 0.23 ml of the mixed solvent was used per 1 mg of the crude product. The final cooling temperature for recrystallization was set to room temperature (27 ° C.).

The purity of the obtained di-n-octyldithienobenzodithiophene was 99.4% by liquid chromatography.
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 8.16 (s, 2H), 7.00 (s, 2H), 2.96 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 20H), 0.88 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 526 (M}} +, 100%), 427 (M + -C 7 H 15, 48), 328 (M + -2C 7 H 15, 35).
Melting point: 180.7-181.2 ° C.

  15.0 mg of the obtained di-n-octyldithienobenzodithiophene and 1.48 g of toluene (Pure grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 60 ° C., and then allowed to stand at room temperature (27 ° C.). It was confirmed that the compound was completely dissolved and suitable for film formation by drop casting and ink jet.

  Di n-octyl dithieno was added by adding 3.0 g of the obtained di n-octyl dithienobenzodithiophene and 1.4 g of toluene (Pure grade manufactured by Wako Pure Chemical Industries, Ltd.) and heating to 50 ° C. to dissolve the compound. An organic semiconductor material containing benzodithiophene was prepared (0.21% by weight colorless solution). According to liquid chromatography analysis, the purity of di-n-octyldithienobenzodithiophene was 99.4%. Further, the solution was allowed to stand in the air for 48 hours and then subjected to liquid chromatography analysis. However, there was no decrease in purity and no oxide was detected.

  Then, an organic semiconductor material 0 obtained on an n-type highly doped silicon substrate (manufactured by Semi-Tech, resistance value: 0.001 to 0.004Ω, with a silicon oxide film of 200 nm on the surface) having a diameter of 2 inches in air. .5 ml was filled in a syringe, and the solution passed through a 0.2 μm filter was drop-cast. The film was naturally dried at room temperature (27 ° C.) to prepare a thin film of di-n-octyldithienobenzodithiophene having a film thickness of 58 nm.

  A shadow mask having a channel length of 45 μm and a channel width of 1500 μm was placed on the organic thin film, and gold was vacuum-deposited to form an electrode. Thus, a bottom gate-top contact type p-type organic thin film transistor was produced.

The electrical properties of the organic thin film transistor thus produced were measured in 1V increments with a drain voltage (Vd = -50V) and a gate voltage (Vg) of +5 to -60V using a semiconductor parameter analyzer (manufactured by Agilent Technologies, (trade name) B1500A). And the transfer characteristics were evaluated. The hole carrier mobility was 1.28 cm ² / V · s, and the current on / off ratio was 8.1 × 10 ⁷ .

Example 2
Dithienobenzodithiophene was obtained by the same method as in Steps (A) and (B) of Example 1.

(Synthesis of di-n-decanoyldithienobenzodithiophene (step (C)))
A yellow solid of di-n-decanoyldithienobenzodithiophene was obtained in a yield of 84% by the same method as in Example 1 except that decanoyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of octanoyl chloride. .
¹ H-NMR (heavy benzene, 80 ° C.): δ = 7.72 (s, 2H), 7.26 (s, 2H), 2.58 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 24H), 0.86 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 610 (M}} +, 100%), 498 (M + -C 8 H 17 +1,41), 483 (M + -C 9 H 19, 16).

(Synthesis of di-n-decyldithienobenzodithiophene (step (D)))
Under a nitrogen atmosphere, 251 mg (1.88 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries), 102 mg (2.68 mmol) of lithium aluminum hydride (manufactured by Wako Pure Chemical Industries), and 10 ml of diethyl ether were added to a 100 ml Schlenk reaction vessel. To this mixture, a suspension mixture of 192 mg (0.314 mmol) of di-n-decanoyldithienobenzodithiophene and 25 ml of diethyl ether was added at room temperature. After stirring at 30 ° C. for 48 hours, the reaction was stopped by cooling with water and adding water. Further, 3N hydrochloric acid was added, followed by extraction with toluene. The organic phase was washed with water and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the obtained residue was purified by silica gel column chromatography (hexane / toluene = 10/1, volume ratio) and recrystallized and purified twice from hexane (pure grade manufactured by Wako Pure Chemical Industries, Ltd.). Furthermore, recrystallization purification was performed twice from toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) to obtain 75 mg of pale yellow scaly crystals of di-n-decyldithienobenzodithiophene (yield 41%). In the recrystallization, 0.26 ml of the solvent was used per 1 mg of the crude product. The final cooling temperature for recrystallization was set to room temperature (27 ° C.).

The purity of the obtained di-n-decyldithienobenzodithiophene was 99.5% according to liquid chromatography.
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 8.16 (s, 2H), 7.00 (s, 2H), 2.94 (t, J = 7.2 Hz, 4H), 1.76 (M, 4H), 1.27 (m, 28H), 0.88 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 582 (M}} +, 100%), 455 (M + -C 9 H 19, 43), 328 (M + -2C 9 H 19, 23).
Melting point: 169.6-170.2 ° C.

  Add 18.2 mg of the obtained di-n-decyldithienobenzodithiophene and 1.50 g of toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.), heat and dissolve at 60 ° C., and leave it at room temperature (27 ° C.) for a solution. Was prepared. It was confirmed that the compound was completely dissolved and suitable for film formation by drop casting and ink jet.

A bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1 except that di-n-decyldithienobenzodithiophene was used instead of di-n-octyldithienobenzodithiophene. . The hole carrier mobility was 1.50 cm ² / V · s, and the current on / off ratio was 1.0 × 10 ⁸ .

Example 3
Dithienobenzodithiophene was obtained by the same method as in Steps (A) and (B) of Example 1.

(Synthesis of di-n-dodecanoyldithienobenzodithiophene (step (C)))
A yellow solid of di-n-dodecanoyldithienobenzodithiophene was obtained in a yield of 87% by the same method as in Example 1 except that dodecanoyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of octanoyl chloride. .
¹ H-NMR (heavy benzene, 80 ° C.): δ = 7.72 (s, 2H), 7.25 (s, 2H), 2.58 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 32H), 0.86 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 667 (M}} +, 100%), 526 (M + -C 10 H 21 +1,39), 511 (M + -C 11 H 23, 15).

(Synthesis of di-n-dodecyldithienobenzodithiophene (step (D)))
The pale yellow color of di-n-dodecyldithienobenzodithiophene was obtained in the same manner as in Example 1 except that di-n-dodecanoyldithienobenzodithiophene was used instead of di-n-octanoyldithienobenzodithiophene. Scale-like crystals were obtained with a yield of 38%.

The purity of the obtained di-n-dodecyldithienobenzodithiophene was 99.6% by liquid chromatography.
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 8.15 (s, 2H), 6.99 (s, 2H), 2.94 (t, J = 7.2 Hz, 4H), 1.76 (M, 4H), 1.27 (m, 36H), 0.88 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 639 (M}} +, 100%), 483 (M + -C 11 H 23, 37), 328 (M + -2C 11 H 23, 18).
Melting point: 160.2-160.6 ° C.

  19.4 mg of the obtained di-n-dodecyldithienobenzodithiophene and 1.87 g of toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 60 ° C., and then allowed to stand at room temperature (27 ° C.) Was prepared. It was confirmed that the compound was completely dissolved and suitable for film formation by drop casting and ink jet.

A bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1 except that di-n-dodecyldithienobenzodithiophene was used instead of di-n-octyldithienobenzodithiophene. . The hole carrier mobility was 1.46 cm ² / V · s, and the current on / off ratio was 1.1 × 10 ⁸ .

Comparative Example 1
Dithienobenzodithiophene was obtained by the same method as in Steps (A) and (B) of Example 1.

(Synthesis of di-n-hexanoyldithienobenzodithiophene)
A yellow solid of di-n-hexanoyldithienobenzodithiophene was obtained in a yield of 70% by the same method as in Example 1 except that hexanoyl chloride (manufactured by Wako Pure Chemical Industries, Ltd.) was used instead of octanoyl chloride. .
¹ H-NMR (heavy benzene, 80 ° C.): δ = 7.73 (s, 2H), 7.26 (s, 2H), 2.58 (t, J = 7.2 Hz, 4H), 1.71 (M, 4H), 1.28 (m, 8H), 0.86 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 498 (M}} +, 100%), 442 (M + -C 4 H 9 +1,46), 427 (M + -C 5 H 11, 13).

(Synthesis of di-n-hexyldithienobenzodithiophene)
A white solid of di-n-hexyldithienobenzodithiophene was prepared in the same manner as in Example 1 except that di-n-hexanoyldithienobenzodithiophene was used instead of di-n-octanoyldithienobenzodithiophene. Was obtained in a yield of 31%.

The purity of the obtained di-n-hexyldithienobenzodithiophene was 99.1% according to liquid chromatography.
¹ H-NMR (CDCl ₃ , 21 ° C.): δ = 8.17 (s, 2H), 7.00 (s, 2H), 2.97 (t, J = 7.2 Hz, 4H), 1.78 (M, 4H), 1.28 (m, 12H), 0.88 (t, J = 7.0 Hz, 6H).
_{^{MS m / z: 470 (M}} +, 100%), 399 (M + -C 5 H 11, 57), 328 (M + -2C 5 H 11, 47).
Melting point: 190.2-190.4 ° C.

  When 16.5 mg of the obtained di-n-hexyldithienobenzodithiophene and 1.63 g of toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 60 ° C., and then allowed to stand at room temperature (27 ° C.) The solid was immediately precipitated, and the compound was not suitable for film formation by drop casting or ink jet.

  The novel dithienobenzodithiophene derivative of the present invention provides high carrier mobility and is excellent in solubility in a solvent, so that an organic semiconductor thin film can be easily produced, and a semiconductor represented by an organic thin film transistor Application as a device material can be expected.

; It is a figure which shows the structure by the cross-sectional shape of an organic thin-film transistor.

(A): Bottom gate-top contact type organic thin film transistor (B): Bottom gate-bottom contact type organic thin film transistor (C): Top gate-top contact type organic thin film transistor (D): Top gate-bottom contact type organic thin film transistor 1: Organic semiconductor layer 2: Substrate 3: Gate electrode 4: Gate insulating layer 5: Source electrode 6: Drain electrode

Claims (7)

A dithienobenzodithiophene derivative represented by the following general formula (1):

(Wherein, the substituents R ¹ and R ² are the same or different and are composed of an n-heptyl group, an n-octyl group, an alkyl group having 10 carbon atoms, an alkyl group having 12 carbon atoms, and an alkyl group having 14 carbon atoms. The substituent selected from the above is shown.) Di-n-heptyldithienobenzodithiophene, di-n-octyldithienobenzodithiophene, di-n-decyldithienobenzodithiophene, di-n-dodecyldithienobenzodithiophene and di-n-tetradecyldithienobenzodithiophene The dithienobenzodithiophene derivative according to claim 1, which is a compound selected from the group consisting of: 3. The dithienobenzodithiophene derivative according to claim 1, wherein the dithienobenzodithiophene derivative exhibits a solubility of 1 wt% or more at room temperature in an aromatic hydrocarbon solvent having 7 to 13 carbon atoms. The dithienobenzodithiophene derivative according to any one of claims 1 to 3, which exhibits a solubility of 1% by weight or more with respect to toluene at room temperature. The organic semiconductor layer made of the dithienobenzodithiophene derivative according to any one of claims 1 to 4 provided with a source electrode and a drain electrode on a substrate, and a gate electrode are laminated via an insulating layer. An organic thin film transistor characterized by the above. The organic semiconductor layer is an organic semiconductor layer formed by subjecting the solution of the dithienobenzodithiophene derivative according to any one of claims 1 to 4 to a drop casting method. Organic thin film transistor. The organic thin film transistor according to claim 5, wherein the organic thin film transistor is a p-type transistor.

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