JP6079259B2 - Organic semiconductor layer and organic thin film transistor - Google Patents

Description

  The present invention relates to an organic semiconductor layer and an organic thin film transistor using a novel dithienobenzodifuran derivative that can be developed into an electronic material such as an organic semiconductor material, and is particularly easy to form a film because of its excellent heat resistance. The present invention relates to an organic semiconductor layer and an organic thin film transistor using a novel dithienobenzodifuran derivative that can be developed into an organic semiconductor solution.

  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-semiconductor material which comprises this organic-semiconductor layer, the appearance of the organic-semiconductor 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. Organic semiconductor materials used for such coating methods include low molecular weight and high molecular weight materials, but low molecular weight materials that can obtain carrier mobility exceeding 1.0 cm ² / Vs are preferred. preferable. Furthermore, it is preferable from the viewpoint of device fabrication process that it has a solubility of 1.5% by weight or more at room temperature and also has a heat resistance of 150 ° C. or more. However, there is currently no known low molecular weight organic semiconductor material that combines high carrier mobility, high solubility, and high heat resistance.

  Examples of the low molecular weight material include bis ((triisopropylsilyl) ethynyl) pentacene (see, for example, Non-Patent Document 1), dialkyl-substituted benzothienobenzothiophene (see, for example, Patent Document 1), and dialkyldithienobenzo. Dithiophene (see, for example, Patent Document 2) has been proposed.

Republished WO2008 / 047896 (see, for example, the claims) JP-T-2011-526588 (see, for example, the claims)

Journal of Polymer Science: Part B: Polymer Physics, 2006, 44, 3631-3641

However, bis ((triisopropylsilyl) ethynyl) pentacene described in Non-Patent Document 1 has a coating film mobility of 0.3 to ¹ cm ² / Vs. It is reported to drop to ² cm ² / Vs. Also, in the case of dialkyl-substituted benzothienobenzothiophene described in Patent Document 1, it has been reported that transistor operation is lost when heat treatment is performed at 130 ° C. 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.

  Therefore, an organic semiconductor layer made of a coating-type organic semiconductor material having high carrier mobility, high heat resistance and high solubility is desired, and the present invention consists of a novel organic semiconductor material that solves the conventional problems. An object of the present invention is to provide an organic semiconductor layer and an organic thin film transistor using the same.

  As a result of intensive studies to solve the above problems, the present inventor has found that an organic semiconductor layer made of a novel dithienobenzodifuran derivative exhibiting high solubility provides high carrier mobility and high heat resistance. The headline and the present invention have been completed.

  That is, the present invention relates to an organic semiconductor layer characterized by comprising a dithienobenzodifuran 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、水素、炭素数１〜１２のアルキル基、炭素数４〜２０のアリール基を示す。）
以下に、本発明を詳細に説明する。

(Here, the substituents R ¹ and R ² are the same or different and each represents hydrogen, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 4 to 20 carbon atoms.)
The present invention is described in detail below.

The organic semiconductor layer of the present invention is composed of a dithienobenzodifuran derivative represented by the above general formula (1). Here, the substituents R ¹ and R ² are the same or different and each represents hydrogen, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 4 to 20 carbon atoms.

Examples of the alkyl group having 1 to 12 carbon atoms in the substituents R ¹ and R ² include a methyl group, n-propyl group, n-butyl group, isobutyl group, tert-butyl group, n-pentyl group, neopentyl group, n -Hexyl group, n-heptyl group, n-octyl group, n-nonyl group, n-decyl group, n-dodecyl group, 2-ethylhexyl group, cyclohexyl group, cyclooctyl group and other alkyl groups.

Examples of the aryl group having 4 to 20 carbon atoms in the substituents R ¹ and R ² include a phenyl group, p-tolyl group, p- (n-hexyl) phenyl group, p- (n-octyl) phenyl group, p- (Nonyl) phenyl group, 2-thienyl group, 5- (n-butyl) -2-thienyl group, 5- (n-hexyl) -2-thienyl group, 5- (n-octyl) -2-thienyl group, A 2-furyl group, a 5- (n-butyl) -2-furyl group, a 5- (n-hexyl) -2-furyl group, a 5- (n-octyl) -2-furyl group, and the like can be given.

  Among them, an alkyl group having 1 to 12 carbon atoms is preferable because of its high heat resistance and high solubility, and an excellent organic semiconductor layer. An n-butyl group, an n-pentyl group, an n-hexyl group, n -Heptyl group, n-octyl group and n-nonyl group are particularly preferred.

  Specific examples of the dithienobenzodifuran derivative include the following.

そして、より好ましいものとしては、ジｎ−ペンチルジチエノベンゾジフラン、ジｎ−ヘキシルジチエノベンゾジフラン、ジｎ−ヘプチルジチエノベンゾジフラン、ジｎ−オクチルジチエノベンゾジフラン等を挙げることができる。

More preferable examples include di-n-pentyldithienobenzodifuran, di-n-hexyldithienobenzodifuran, di-n-heptyldithienobenzodifuran, di-n-octyldithienobenzodifuran, and the like. be able to.

The dithienobenzodifuran derivative is excellent in solubility in a solvent, and is suitable for film formation by a drop cast method for forming an organic semiconductor layer, particularly an ink jet method. Among them, it is preferable that it exhibits a solubility of 1.5% by weight or more with respect to the solvent at room temperature. Examples of the solvent used in this case include toluene, xylene, mesitylene, ethylbenzene, pentylbenzene, hexylbenzene, and octyl. C7-14 aromatic hydrocarbon solvent such as benzene, cyclohexylbenzene, indane, tetralin; C6-C14 aliphatic hydrocarbon solvent such as hexane, heptane, octane, decane, dodecane, tetradecane; o -Halogen solvents having 1 to 7 carbon atoms such as dichlorobenzene, chlorobenzene, trichlorobenzene, 1,2-dichloroethane, 1,1,2,2-tetrachloroethane, chloroform, dichloromethane; tetrahydrofuran (hereinafter referred to as THF). 1,2-dimethoxyethane, dioxy Ether solvents such as ethyl; ester solvents such as ethyl acetate and γ-butyrolactone; amide solvents such as N, N-dimethylformamide and N-methyl-2-pyrrolidone (hereinafter referred to as NMP); Among them, since it is possible to obtain a high boiling point solution, it is preferably an aromatic hydrocarbon solvent having 7 to 14 carbon atoms such as toluene, xylene, mesitylene, pentylbenzene, cyclohexylbenzene, tetralin, In particular, toluene, xylene, mesitylene, pentylbenzene, and tetralin are preferable. Here, room temperature is generally also referred to as room temperature, and examples thereof include a temperature of 20 to 26 ° C. The above-mentioned solvents and dithienobenzodifuran represented by the general formula (1) A solution for forming a drop cast film of a dithienobenzodifuran derivative represented by the general formula (1) can be prepared by mixing the derivatives and heating and stirring. The temperature during heating and stirring is preferably 15 to 70 ° C, particularly preferably 20 to 60 ° C. The concentration of the dithienobenzodifuran derivative represented by the general formula (1) when heated and stirred is preferably 0.1 to 10.0% by weight.

  As a method for producing the dithienobenzodifuran derivative, any production method can be used as long as the dithienobenzodifuran derivative can be produced. Since it is possible to produce a benzodifuran derivative, a dithienobenzodifuran derivative is produced by a production method that includes at least the following steps (A) to (C) or at least the following steps (A) to (E). It is preferable to do.

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

  Step (B): In the presence of boron tribromide, 1,4-di (3-bromothienyl) -2,5-dimethoxybenzene obtained by Step (A) was demethylated to give 1,4-di ( 3-bromothienyl) -2,5-dihydroxybenzene production step.

  (C) Step: Dithienobenzodifuran is produced by intramolecular cyclization of 1,4-di (3-bromothienyl) -2,5-dihydroxybenzene obtained in Step (B) in the presence of a palladium catalyst. Process.

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

  (E) step; a step of producing a dithienobenzodifuran derivative by subjecting the diacyl derivative of dithienobenzodifuran obtained in step (D) to a reduction reaction.

  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−ジメトキシ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−ジメトキシベンゼンを製造する工程である。

Here, in 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-dimethoxybenzene in the presence of a palladium catalyst. This is a process for producing bromothienyl) -2,5-dimethoxybenzene.

  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.

  By cross-coupling the prepared 3-bromothiophene-2-zinc derivative and 1,4-dibromo-2,5-dimethoxybenzene in the presence of a palladium catalyst, 1,4-di (3-bromothienyl)- 2,5-dimethoxybenzene 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.

  (B) The process comprises 1,4-di (3-bromothienyl) -2 by demethylation of 1,4-di (3-bromothienyl) -2,5-dimethoxybenzene in the presence of boron tribromide. , 5-dihydroxybenzene.

  The demethylation reaction can be performed in a temperature range of 0 ° C. to 30 ° C. in a solvent such as dichloromethane and chloroform.

  Step (C) is a step of producing dithienobenzodifuran by intramolecular cyclization of 1,4-di (3-bromothienyl) -2,5-dihydroxybenzene in the presence of a palladium catalyst.

  The intramolecular cyclization reaction is performed using, for example, palladium acetate as a catalyst, 2-ditertiarybutylphosphinobiphenyl, 2-ditertiarybutylphosphino-2′-methylbiphenyl as a ligand, and 2,6-ditertiarybutyl. It can be carried out in a temperature range of 80 ° C. to 120 ° C. in a solvent such as toluene and dimethoxyethane in the presence of potassium acetate base using -4-methylphenol as a stabilizer.

  Other examples of the palladium catalyst include tetrakis (triphenylphosphine) palladium and bis (triphenylphosphine) dichloropalladium.

  In addition, this cyclization reaction can also be implemented, for example using the method described in Journal of Organic Chemistry (USA), 2007, 72, 5119-5128.

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

  Examples of the acyl chloride compound include pentanoyl chloride, hexanoyl chloride, heptanoyl chloride, octanoyl chloride and the like. 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 (E) is a step of producing a dithienobenzodifuran derivative by subjecting a diacyl derivative of dithienobenzodifuran to a reduction reaction.

  In the reduction reaction of dithienobenzodifuran diacyl, for example, hydrazine is used as a reducing agent in diethylene glycol, ethylene glycol or triethylene glycol in the presence of potassium hydroxide or sodium hydroxide in a temperature range of 80 ° C to 250 ° C. It can be carried out. Further, for example, sodium borohydride / aluminum chloride can be used as a reducing agent, and the reaction can be carried out in a temperature range of −10 ° C. to 80 ° C. in a solvent of diethyl ether, diisopropyl ether, methyl tertiary butyl ether or THF.

  Further, the produced dithienobenzodifuran derivative can be purified by subjecting it to column chromatography or the like, and as a separating agent in that case, for example, silica gel, alumina, as a solvent, hexane, heptane, toluene, chloroform Etc.

  Further, the produced dithienobenzodifuran 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 dithienobenzodifuran derivative solution 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). In this case, by cooling the solution, crystals of the dithienobenzodifuran derivative are precipitated and isolated, and the final cooling temperature in 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 dithienobenzodifuran derivative has excellent characteristics as an organic semiconductor material because it provides high carrier mobility, and has high solubility in a solvent, so that it is a drop casting method, particularly an inkjet method. Thus, the organic semiconductor layer can be formed easily and efficiently.

  An 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 dithienobenzodifuran derivative is formed on the organic semiconductor layer. An organic thin film transistor can be obtained by using an organic semiconductor layer.

  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 formed of the dithienobenzodifuran derivative. This 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.

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

  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: polymethyl methacrylate, polymethyl acrylate, polyimide, polycarbonate, polyvinyl phenol, polyvinyl alcohol, poly (diisopropyl fumarate), poly (diethyl fumarate), polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polycyclopentane, Polycyclohexane, polycyclohexane-ethylene copolymer, polyfluorinated cyclopentane, polyfluorinated cyclohexane, polyfluorinated cyclohexane-ethylene The plastic material of the polymer, and the like can be given. The surfaces of these gate insulating layers are, for example, octadecyltrichlorosilane, decyltrichlorosilane, decyltrimethoxysilane, octyltrichlorosilane, octadecyltrimethoxysilane, β-phenethyltrichlorosilane, β-phenethyltrimethoxysilane, phenyltrichlorosilane. Silanes such as phenyltrimethoxysilane; phosphonic acids such as octadecylphosphonic acid, decylphosphonic acid and octylphosphonic acid, 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 of the present invention is used, for example, a drop casting method such as spin coating, cast coating, inkjet, slit coating, etc .; blade coating; dip coating, screen printing, gravure printing, flexographic printing, etc. It is possible to use, and among them, it is possible to easily and efficiently form an organic semiconductor layer, and therefore it is preferable to use a drop casting method such as spin coating, cast coating, and inkjet, and particularly preferably inkjet. . 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 of the present invention can be annealed at 40 to 200 ° C. after coating and drying.

  The organic semiconductor layer and the organic thin film transistor of the present invention are used for an organic semiconductor layer of a transistor such as an electronic paper, an organic EL display, a liquid crystal display, and an IC tag (RFID tag); an organic EL display material; an organic semiconductor laser material; Battery materials; can be used for electronic materials such as photonic crystal materials.

  The organic semiconductor layer made of the novel dithienobenzodifuran derivative of the present invention has high carrier mobility and high heat resistance, and is extremely effective as a semiconductor device material typified by an organic thin film transistor. Is.

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

  Mass spectra were used for product identification. The mass spectrum (MS) was measured by an electron impact (EI) method (70 electron volts) by directly introducing a sample using (trade name) JEOL JMS-700 (manufactured by JEOL).

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

Liquid chromatographic analysis was used to measure the purity of the dithienobenzodifuran derivative.
Apparatus; manufactured by Tosoh (controller; PX-8020, pump; CCPM-II, degasser; SD-8022).
Column: manufactured by Tosoh Corporation (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).

Synthesis Example 1 (Synthesis of 1,4-di (3-bromothienyl) -2,5-dimethoxybenzene (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), 296 mg (1.00 mmol) of 1,4-dibromo-2,5-dimethoxybenzene (manufactured by Sigma-Aldrich) and tetrakis (triphenyl) as a catalyst Phosphine) palladium (manufactured by Tokyo Chemical Industry Co., Ltd.) 116 mg (0.0338 mmol, 10 mol% with respect to 1,4-dibromo-2,5-dimethoxybenzene) and 10 ml of THF were added. After carrying out the reaction at 65 ° C. for 30 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 = 5/1) and further recrystallized from toluene to obtain 1,4-di (3-bromothienyl) -2, 189 mg of 5-dimethoxybenzene pale yellow solid was obtained (yield 41%).
MS m / z: 460 (M ⁺ , 100%), 300 (M ⁺ -2Br, 23).

Synthesis Example 2 (Synthesis of 1,4-di (3-bromothienyl) -2,5-dihydroxybenzene (step (B)))
Under a nitrogen atmosphere, 189 mg (0.411 mmol) of 1,4-di (3-bromothienyl) -2,5-dimethoxybenzene and 6 ml of dichloromethane were added to a 100 ml Schlenk reaction vessel. The mixture was cooled to 0 ° C., and 1.2 ml (1.2 mmol) of a solution of boron tribromide (manufactured by Wako Pure Chemical Industries, Ltd., 1.0 M) in dichloromethane was added. The obtained mixture was stirred at 0 ° C. for 10 hours, and then the reaction was stopped by adding water at 0 ° C. 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 washed twice with hexane to obtain 158 mg of a light yellow solid of 1,4-di (3-bromothienyl) -2,5-dihydroxybenzene (yield 89%). .
MS m / z: 432 (M ^<+> , 100%), 151 (M ^<+ > / 2, 10).

Synthesis Example 3 (Synthesis of dithienobenzodifuran (step (C)))
Under a nitrogen atmosphere, in a 100 ml Schlenk reaction vessel, 179 mg (1.82 mmol) of potassium acetate (manufactured by Wako Pure Chemical Industries), 34.4 mg (manufactured by Sigma-Aldrich) of 2-ditertiary butylphosphino-2′-methylbiphenyl. 110 mmol), 2,6-ditertiary butyl-4-methylphenol (manufactured by Wako Pure Chemical Industries) 161 mg (0.730 mmol), 1,4-di (3-bromothienyl) -2,5-dihydroxybenzene 158 mg (0 365 mmol), toluene 2 ml, dimethoxyethane 1 ml, and palladium acetate (manufactured by Wako Pure Chemical Industries, Ltd., for organic synthesis) 16.4 mg (0.073 mmol) were added. Heated at 100 ° C. for 3 days. The resulting reaction mixture was cooled to room temperature, toluene and water were added, phase separation was performed, and the organic phase was washed twice with water and dried over anhydrous sodium sulfate. After concentration under reduced pressure, the resulting residue was washed twice with hexane to obtain 57 mg of a dithienobenzodifuran pale yellow solid (yield 57%).
MS m / z: 270 (M ^<+> , 100%), 135 (M ^<+ > / 2, 14).

Synthesis Example 4 (Synthesis of dihexanoyl dithienobenzodifuran (step (D)))
Dithienobenzodifuran 55.0 mg (0.203 mmol) and dichloromethane 10 ml were added to a 100 ml Schlenk reaction vessel. This mixture was ice-cooled, and 95.3 mg (0.715 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries) and 76.5 mg (0.568 mol) of hexanoyl chloride (manufactured by Sigma-Aldrich) were added. The resulting mixture was stirred at room temperature for 30 hours, then ice-cooled and water was added to stop the reaction. The resulting slurry mixture was heated and dichloromethane was removed by distillation. Water dispersion obtained by adding water was filtered. The resulting yellow solid was further washed with water and methanol. After drying under reduced pressure, 87.1 mg of dihexanoyl dithienobenzodifuran yellow solid was obtained (yield 92%).
^{MS m / z: 466 (M} +, 100%), 410 (M + -C 4 H 9 +1,49).

Synthesis Example 5 (Synthesis of di-n-hexyldithienobenzodifuran (step (E)))
To a 100 ml Schlenk reaction vessel, 87.1 mg (0.187 mmol) of dihexanoyl dithienobenzodifuran, 10 ml of THF, and 125 mg (0.935 mmol) of aluminum chloride (manufactured by Wako Pure Chemical Industries, Ltd.) were added. After cooling to 0 ° C., 70.7 mg (1.87 mmol) of sodium borohydride (Wako Pure Chemical Industries) was further added. After heating at 60 ° C. for 5 hours, the reaction was stopped by cooling to 0 ° C. and carefully adding water. The aqueous phase was acidified with 3N hydrochloric acid and extracted with toluene. After phase separation, water washing of the organic phase was repeated 3 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), recrystallized and purified three times from toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.), and di-n-hexyldithienobenzo 33.6 mg of difuran pale yellow crystals were obtained (41% yield).

The purity of the obtained di-n-hexyldithienobenzodifuran was 99.7% by liquid chromatography.
_{^{MS m / z: 438 (M}} +, 100%), 367 (M + -C 5 H 11, 58), 296 (M + -2C 5 H 11, 43)
Example 1
10.4 mg of di-n-hexyldithienobenzodifuran obtained in Synthesis Example 5 and 0.683 g of toluene (Pure Grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 50 ° C., and then at room temperature (25 ° C.) The solution was allowed to cool to a drop casting film-forming solution. The solution state is maintained even after 10 hours at 25 ° C. (di-n-hexyldithienobenzodifuran concentration is 1.50% by weight), and it is confirmed that the compound is suitable for film formation by drop casting and ink jet. did.

  And the drop cast obtained on a silicon substrate (semi-tech, resistance value: 0.001 to 0.004Ω, with a silicon oxide film of 200 nm on the surface) that is n-type highly doped with arsenic having a diameter of 2 inches under air The microsyringe was filled with 0.2 ml of the solution for film formation and drop cast. The film was naturally dried at room temperature (25 ° C.) to prepare an organic semiconductor layer of di-n-hexyldithienobenzodifuran having a film thickness of 75 nm.

  A shadow mask having a channel length of 30 μm and a channel width of 250 μm was placed on the organic semiconductor layer, and gold was vacuum-deposited to form a source / drain electrode pair, thereby producing a bottom gate-top contact type p-type organic thin film transistor.

The electrical properties of the produced organic thin film transistor were scanned using a semiconductor parameter analyzer with a drain voltage (Vd = -50V) and a gate voltage (Vg) from +5 to -60V in increments of 1V to evaluate transfer characteristics. The hole carrier mobility was 1.38 cm ² / V · s, and the current on / off ratio was 6.5 × 10 ⁷ .

Furthermore, the electrical properties of the organic thin film transistor after annealing at 150 ° C. for 15 minutes were measured. The hole carrier mobility was 1.31 cm ² / V · s, the current on / off ratio was 5.4 × 10 ⁷ , and no deterioration in performance due to heat treatment was observed.

Synthesis Example 6 (Synthesis of diheptanoyl dithienobenzodifuran (step (D)))
A yellow solid of diheptanoyl dithienobenzodifuran was obtained in the same manner as in Synthesis Example 4 except that heptanoyl chloride (manufactured by Sigma-Aldrich) was used instead of hexanoyl chloride used in Synthesis Example 4. %.

Synthesis Example 7 (Synthesis of di-n-heptyldithienobenzodifuran (step (E)))
Di n-heptyl dithienobenzodifuran was prepared in the same manner as in Synthesis Example 5 except that diheptanoyl dithienobenzodifuran was used instead of dihexanoyl dithienobenzodifuran used in Synthesis Example 5. Was obtained in a yield of 38%.

Example 2
11.6 mg of di-n-heptyldithienobenzodifuran obtained in Synthesis Example 7 and 0.763 g of toluene (Pure Grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 50 ° C, and then at room temperature (25 ° C) The solution was allowed to cool to a drop casting film-forming solution. The solution state is maintained even after 10 hours at 25 ° C. (di-n-heptyldithienobenzodifuran concentration is 1.50% by weight), and it is confirmed that the compound is suitable for film formation by drop casting and ink jet. did.

Then, a bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1. The hole carrier mobility was 1.43 cm ² / V · s, and the current on / off ratio was 1.3 × 10 ⁸ .

Furthermore, the electrical properties of the organic thin film transistor after annealing at 150 ° C. for 15 minutes were measured. The carrier mobility of holes was 1.36 cm ² / V · s, the current on / off ratio was 1.0 × 10 ⁸ , and no deterioration in performance due to heat treatment was observed.

Synthesis Example 8 (Synthesis of dioctanoyl dithienobenzodifuran (step (D)))
A yellow solid of dioctanoyldithienobenzodifuran was obtained in the same manner as in Synthesis Example 4 except that octanoyl chloride (manufactured by Sigma-Aldrich) was used instead of hexanoyl chloride used in Synthesis Example 4. %.

Synthesis Example 9 (Synthesis of di-n-octyldithienobenzodifuran (step (E)))
Di n-octyl dithienobenzodifuran was prepared in the same manner as in Synthesis Example 5 except that dioctanoyl dithienobenzodifuran was used instead of dihexanoyl dithienobenzodifuran used in Synthesis Example 5. Was obtained in a yield of 42%.

Example 3
11.1 mg of di-n-octyldithienobenzodifuran obtained in Synthesis Example 9 and 0.730 g of toluene (Pure Grade manufactured by Wako Pure Chemical Industries, Ltd.) were added and dissolved by heating at 50 ° C., and then at room temperature (25 ° C.) The solution was allowed to cool to a drop casting film-forming solution. The solution state is maintained even after 10 hours at 25 ° C. (di-n-octyldithienobenzodifuran concentration is 1.50% by weight), and it is confirmed that the compound is suitable for film formation by drop casting and ink jet. did.

Then, a bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1. The hole carrier mobility was 1.51 cm ² / V · s, and the current on / off ratio was 2.0 × 10 ⁷ .

Furthermore, the electrical properties of the organic thin film transistor after annealing at 150 ° C. for 15 minutes were measured. The hole carrier mobility was 1.44 cm ² / V · s, the current on / off ratio was 1.5 × 10 ⁷ , and no deterioration in performance due to heat treatment was observed.

Comparative Example 1
Di n-octylbenzothienobenzothiophene was synthesized as follows according to the method described in the republished WO2008 / 047896.

In a 100 ml Schlenk reaction vessel, 2,7-di (1-octynyl) (1) benzothieno (3,2-b) (1) benzothiophene 286 mg (0.626 mmol), 10% Pd / C (manufactured by Wako Pure Chemical Industries, Ltd.) 62 mg and 10 ml of toluene (dehydration grade manufactured by Wako Pure Chemical Industries) were added. A hydrogen balloon was attached, and pressure reduction-hydrogen replacement with an aspirator was repeated three times, followed by stirring at room temperature for 10 hours. The solvent was distilled off under reduced pressure, and the residue was purified by silica gel column chromatography (hexane) and recrystallized and purified twice from hexane (pure grade manufactured by Wako Pure Chemical Industries, Ltd.). White solid of di-n-octylbenzothienobenzothiophene 227 mg was obtained (yield 78%).
MS m / z: 464 (M ^<+> , 100%).

  12.1 mg of the obtained di-n-octylbenzothienobenzothiophene and 0.801 g of toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, dissolved by heating at 50 ° C., and then allowed to cool to room temperature (25 ° C.). A solution (di-n-octylbenzothienobenzothiophene concentration of 1.50% by weight) was prepared.

Then, a bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1. The hole carrier mobility was 0.167 cm ² / V · s, and the current on / off ratio was 1.3 × 10 ⁶ .

  Furthermore, the electrical properties of the organic thin film transistor after annealing at 150 ° C. for 15 minutes were measured. However, the transistor operation cannot be obtained, and the material is inferior in heat resistance.

Comparative Example 2
11.8 mg of 6,13-bis ((triisopropylsilyl) ethynyl) pentacene (manufactured by Sigma-Aldrich) and 0.775 g of toluene (pure grade manufactured by Wako Pure Chemical Industries, Ltd.) were added, and the mixture was heated and dissolved at 50 ° C. at room temperature ( 25 ° C.) to prepare a solution (6,13-bis ((triisopropylsilyl) ethynyl) pentacene concentration of 1.50% by weight).

Then, a bottom gate-top contact type p-type organic thin film transistor was produced in the same manner as in Example 1. The hole carrier mobility was 0.0524 cm ² / V · s, and the current on / off ratio was 1.2 × 10 ⁵ .

Furthermore, the electrical properties of the organic thin film transistor after annealing at 150 ° C. for 15 minutes were measured. The hole carrier mobility was 0.00814 cm ² / V · s, the current on / off ratio was 1.5 × 10 ⁴ , and the performance was poor, and the material was inferior in heat resistance.

  The organic semiconductor layer comprising the novel dithienobenzodifuran derivative of the present invention provides high carrier mobility and is excellent in heat resistance of transistor elements, so that it can be expected to be applied as a semiconductor device material typified by organic thin film transistors. .

; 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 (4)

An organic semiconductor layer comprising a dithienobenzodifuran derivative represented by the following general formula (1).

(Here, the substituents R ¹ and R ² are the same or different and each represents hydrogen, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 4 to 20 carbon atoms.) The substituents R ¹ and R ² in the general formula (1) are the same or different, and are composed of a dithienobenzodifuran derivative which is an alkyl group having 1 to 12 carbon atoms. Organic semiconductor layer. The organic semiconductor layer according to claim 1, wherein the organic semiconductor layer is formed by a drop cast method. An organic thin film transistor, comprising: an organic semiconductor layer according to any one of claims 1 to 3, wherein a source electrode and a drain electrode are provided on a substrate; and a gate electrode stacked via an insulating layer.

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