JPWO2014115749A1 - Organic semiconductor material for solution process and organic semiconductor device - Google Patents

Abstract

The organic semiconductor material for solution process is represented by Formula 1. In Formula 1, Y1 and Y2 are each independently a chalcogen atom, one of R1 and R2 is a branched alkyl group, and the other is hydrogen.

Description

  The present invention relates to an organic semiconductor material for solution processing and an organic semiconductor device.

  In recent years, thin film devices using organic semiconductors such as organic FET devices and organic EL devices have attracted attention and have been put into practical use. Various compounds have been researched and developed as organic semiconductor materials. For example, dinaphthothienothiophene (hereinafter referred to as DNTT) has attracted attention as a material that exhibits excellent charge mobility and exhibits organic semiconductor material properties (patents). References 1, 2).

International Publication No. 2008/050726 International Publication No. 2010/098372

  The DNTT derivatives disclosed in Patent Documents 1 and 2 have poor solubility in organic solvents. For this reason, the subject that the organic-semiconductor layer cannot be manufactured by solution processes, such as the apply | coating method, occurred.

  The present invention has been made in view of the above matters, and provides an organic semiconductor material and an organic semiconductor device for solution process that are excellent in solubility in an organic solvent and can be used for manufacturing an organic semiconductor layer by a solution process such as a coating method. The purpose is to do.

The organic semiconductor material for solution process according to the first aspect of the present invention,
Including a compound represented by Formula 1,
(In Formula 1, Y ¹ and Y ² are each independently a chalcogen atom, one of R ¹ and R ² is a branched alkyl group, and the other is hydrogen.)
It is characterized by that.

  The main chain of the branched alkyl group is preferably C3 or more.

  The main chain of the branched alkyl group is preferably C6 or more.

  The side chain of the branched alkyl group is preferably C2 or more.

  Moreover, it is preferable that the side chain of the branched chain alkyl group is bonded to carbon at the 2-position or more of the main chain.

  Moreover, it is preferable that the side chain of the branched chain alkyl group is bonded to carbon at the 3-position or more of the main chain.

Further, it is preferable that the Y ¹ and Y ² is a sulfur atom or a selenium atom.

The organic semiconductor device according to the second aspect of the present invention is
Including an organic semiconductor material for solution processing according to the first aspect of the present invention,
It is characterized by that.

  The organic semiconductor material for solution process according to the present invention is excellent in solubility in an organic solvent. For this reason, it is possible to produce an organic semiconductor layer by a solution process such as a coating method.

It is a graph which shows the absorption spectrum (FIG. 1 (A)), photoelectron spectrum (FIG. 1 (B)), and out-of-plane XRD (FIG. 1 (C)) of a 2,9-EH-DNTT thin film. It is a graph which shows the absorption spectrum (FIG. 2 (A)), photoelectron spectrum (FIG. 2 (B)), and out-of-plane XRD (FIG. 2 (C)) of a 2-2EH-DNTT thin film. 6 is a graph showing transfer characteristics (FIG. 3A) and output characteristics (FIG. 3B) of a 2-2EH-DNTT transistor element. It is a graph which shows the transfer characteristic (FIG. 4 (A)) and output characteristic (FIG. 4 (B)) of an ODTS processing element.

(Organic semiconductor materials for solution process)
The organic semiconductor material for solution process according to the present embodiment includes a compound represented by Formula 1.

In Formula 1, Y ¹ and Y ² are each independently a chalcogen atom (oxygen, sulfur, selenium, tellurium). Y ¹ and Y ² are preferably a sulfur atom or a selenium atom. Y ¹ and Y ² are preferably the same.

In Formula 1, any ^one of R ¹ and R ² is a branched alkyl group, and the other is hydrogen. The main chain of the branched alkyl group is preferably C3 or more, and more preferably C6 or more. The side chain of the branched alkyl group is C1 or more, and more preferably C2 or more. Further, the side chain is preferably bonded to the carbon at the 2-position or more of the main chain, and more preferably bonded to the carbon at the 3-position or more of the main chain. By separating the side chain from the condensed ring, the intermolecular interaction is increased and the carrier mobility is improved. The branched alkyl group is preferably a saturated branched alkyl group.

  Although it is considered that the branched chain alkyl group has higher solubility in organic solvents as the number of carbon atoms increases, in the examples described later, the main chain carbon number is C6, indicating sufficiently good solubility, If the branched alkyl group is long, the packing at the time of producing the organic semiconductor layer is deteriorated and the semiconductor characteristics may be deteriorated. Therefore, the carbon number of the main chain may be C10 or less.

In the formula 1, in the case where one of R ¹ and R ² is a linear alkyl group and the other is hydrogen, this compound has poor solubility in an organic solvent. For this reason, it is not suitable for manufacturing an organic semiconductor layer using a solution process such as a coating method.

In addition, in the case where a compound in which R ¹ and R ² are both branched alkyl groups in Formula 1, the solubility in an organic solvent is good, while an organic semiconductor produced by a coating method or the like using this compound The layer does not exhibit transistor properties and cannot be used as an organic semiconductor material for solution processing.

  The compound represented by the above formula 1 can be synthesized with reference to known methods disclosed in Patent Document 1 and Patent Document 2. For example, although it can synthesize | combine as follows, it is not limited to this.

As shown in the following Scheme 1, first, from 6-halogeno-2-methoxynaphthalene or 7-halogeno-2-methoxynaphthalene (compound (A)), 6-alkyl-2-methoxynaphthalene or 7-alkyl- 2-methoxynaphthalene (compound (B)) is synthesized. It can be synthesized by reacting compound (A) with a Grignard reagent such as an alkylmagnesium bromide having a branched alkyl group.
Subsequently, the compound (C) is synthesized. The compound (C) can be synthesized by reacting the compound (B) with dimethyl sulfide or the like.
Subsequently, the compound (D) is synthesized. It can be synthesized by reacting compound (C) with tribromoborane or the like.
Subsequently, the compound (E) is synthesized. It can be synthesized by reacting compound (D) with trifluoromethanesulfonic acid.
In the compound (A), ^one of X ¹ and X ² is a halogen atom, and the other is hydrogen. In the compounds (B) to (E), ^one of R ¹ and R ² is a branched alkyl group, and the other is hydrogen.

Moreover, as represented in the following scheme 2, compound (I) is synthesized from 2-methoxynaphthalene (compound (F)) via compound (G) and compound (H). The compounds (G), (H) and (I) can be synthesized in the same manner as the compounds (C), (D) and (E), respectively.

Subsequently, as shown in Scheme 3 below, the compound (J) is synthesized by condensing the above two compounds (compounds (E) and (I)). Furthermore, compound (K) which is a target compound is synthesize | combined by ring-closing compound (J). It can be synthesized by carrying out a ring-closing reaction using iodine in chloroform. In the compounds (E), (J), and (K), ^one of R ¹ and R ² is a branched alkyl group, and the other is hydrogen.

In the above synthesis method, as an example, a synthesis example of a compound in which Y ¹ and Y ² in formula 1 are sulfur atoms has been described, but by using dimethyl selenide or dimethyl ether instead of the above dimethyl sulfide, In Formula 1, a compound in which Y ¹ and Y ² are a selenium atom and an oxygen atom can be synthesized.

  The organic semiconductor material for solution process contains the compound represented by Formula 1, and the compound represented by Formula 1 has high solubility in an organic solvent. Therefore, an organic semiconductor material for solution process containing the compound represented by Formula 1 is used and a solution process such as a coating method such as a spin coating method, an ink jet method, a screen printing method, an offset printing method, or a micro contact printing method is used. Thus, an organic semiconductor layer can be manufactured. In the solution process, it is not necessary to use a vacuum or a high temperature state unlike the vapor deposition method, and a large-area organic semiconductor layer can be realized at low cost.

  Examples of organic solvents in which organic semiconductor materials for solution process are soluble include halogeno hydrocarbon solvents such as chloroform, methylene chloride, and dichloroethane, alcohol solvents such as methanol, ethanol, propyl alcohol, and butanol, octafluoropentanol, and pentane. Fluorinated alcohol solvents such as fluoropropanol, ester solvents such as ethyl acetate, butyl acetate, ethyl benzoate, diethyl carbonate, toluene, hexylbenzene, xylene, mesitylene, chlorobenzene, dichlorobenzene, methoxybenzene, chloronaphthalene, methylnaphthalene , Aromatic hydrocarbon solvents such as tetrahydronaphthalene, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, cyclohexane, dimethylforma De, dimethyl acetamide, amide solvents such as N- methyl pyrrolidone, tetrahydrofuran, diisobutyl ether, ether solvents diphenyl ether, octane, decane, etc. hydrocarbon solvents cyclohexane.

  In addition to the compound represented by Formula 1, the organic semiconductor material for solution process may be mixed with additives and other semiconductor materials for improving the film forming property of the organic semiconductor layer, doping, and the like.

(Organic semiconductor device)
The organic semiconductor device according to the present embodiment is a device using the above-described organic semiconductor material for solution process. Examples of the organic semiconductor device include a field effect transistor having an organic semiconductor layer and a light emitting device having an organic carrier transport layer and / or a light emitting layer. The organic semiconductor device can be manufactured using various conventionally known manufacturing methods, and is not particularly limited.

  As described below, stepwise 2- (2-ethylhexyl) dinaphtho [2,3-b: 2 ′, 3′-f] thieno [2,3-b] thiophene (hereinafter referred to as 2-2-2EH−) DNTT) was synthesized.

(Synthesis of 6- (2-ethylhexyl) -2-methoxynaphthalene (hereinafter, compound 1))
To a solution of 6-bromo-2-methoxynaphthalene (7.14 g, 30 mmol) and Ni (dppp) Cl ₂ (813 mg, 1.5 mmol) in tetrahydrofuran (hereinafter referred to as THF) (30 mL), 2-ethylhexylmagnesium bromide was added. Was added at room temperature and refluxed for 24 hours. A THF solution of 2-ethylhexyl magnesium bromide was prepared by adding 1-bromo-2-ethylhexyl bromide (9.0 mL, 45 mmol) and magnesium (1.17 g, 48 mmol) to THF (7.5 mL). did.
After cooling, the mixture was diluted with water (30 mL) and unreacted magnesium and the resulting solid was filtered off.
The filtrate was extracted with ether (15 mL × 3). The extracted composite was washed with brine (30 mL × 3) and dried over magnesium sulfate. This was dried under reduced pressure to obtain pale yellow oily compound 1 (5.4 g, yield 50%).

The measurement data of the obtained compound 1 are shown below.
¹ H NMR (500MHz, CDCl ₃ ) δ 0.87 (t, J = 7.1 Hz, 3H), 0.92 (t, J = 7.5 Hz, 3H) 1.22 1.37 (m, 8H), 1.67 (sept, J = 6.2 Hz, 2H), 2.68 (t, J = 6.6 Hz, 2H), 3.93 (s, 3H), 7.13 (s, 1H), 7.16 (dd, J = 8.8, 2.6 Hz, 1H), 7.31 (dd, J = 8.6 , 1.3 Hz, 1H), 7.53 (s, 1H), 7.67 (d, J = 8.6 Hz, 1H), 7.69 (d, J = 8.6 Hz, 1H),
¹³ C NMR (126 MHz, CDCl ₃ ); δ11.2, 14.5, 23.4, 23.6, 25.8, 29.2, 32.7, 40.5, 41.4, 55.6, 106.0, 118.9, 126.8, 127.5, 128.9, 129.3, 129.4, 133.2, 137.5 , 157.4;
EIMS (70 eV) m / z = 270 (M ⁺ ). HRMS (APCI) Calcd for C ₁₉ H ₂₆ O: 270.19782; Found: 270.19791.

(Synthesis of 6- (2-ethylhexyl) -3-methylthio-2-methoxynaphthalene (hereinafter Compound 2))
To a solution of Compound 1 (730 mg, 2.7 mmol) in THF (2.7 mL), a 1.59 M hexane solution of n-butyllithium (2.0 mL, 3.2 mmol) was added at −78 ° C.
After the mixture was stirred at room temperature for 1 hour, dimethyl disulfide (0.36 mL, 4.1 mmol) was added at −78 ° C. The resulting mixture was then stirred at room temperature for 18 hours.
The mixture was poured into saturated aqueous ammonium chloride solution (5 mL) and extracted with ether (5 mL × 3).
The extracted composite was washed with brine (5 mL × 3) and dried over magnesium sulfate. This was concentrated under reduced pressure to obtain almost pure yellow oily compound 2 (853 mg, quant.).
The sample for analysis was separated and purified by silica gel column chromatography (developing solvent: dichloromethane-hexane (v / v = 1: 1, R _f = 0.35)).

The measurement data of the obtained compound 2 are shown below.
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.87 (t, J = 7.0 Hz, 3H), 0.89 (t, J = 7.2 Hz, 3H) 1.25-1.36 (m, 8H), 1.64 (sept, J = 6.6 Hz, 2H), 2.55 (s, 1H), 2.66 (t, J = 6.5 Hz, 2H), 3.99 (s, 3H), 7.07 (s, 1H), 7.22 (d, J = 8.3 Hz, 1H), 7.42 (s, 1H) 7.47 (s, 1H), 7.62 (d, J = 8.3 Hz, 1H),
¹³ C NMR (126 MHz, CDCl ₃ ); δ11.2, 14.5, 14.9, 23.4, 25.8, 29.3, 32.8, 40.5, 41.5, 56.2, 105.0, 123.2, 126.3, 126.5, 127.9, 129.6, 129.7, 130.7, 128.0 , 154.3;
EIMS (70 eV) m / z = 316 (M +). HRMS (APCI) Calcd for C ₂₀ H ₂₈ OS: 316.18554; Found: 316.18576.

(Synthesis of 6- (2-ethylhexyl) -3-methylthio-2-hydroxynaphthalene (hereinafter, compound 3))

To a solution obtained by adding compound 2 (681 mg, 2.2 mmol) to dichloromethane (5 mL) was added dropwise a solution of tribromoborane in dichloromethane (about 2 M, 1.1 mL, 4.3 mmol) at −78 ° C.
The mixture was stirred at room temperature for 5 hours and then added to ice (ca. 2 g).
The purified mixture was extracted with dichloromethane (5 mL × 3).
The organic phase was washed with brine (5 mL × 3), dried over magnesium sulfate and concentrated under reduced pressure.
The residue was separated and purified by silica gel column chromatography (developing solvent: dichloromethane-hexane (v / v = 1/1, R _f = 0.28)) to obtain yellow oily compound 3 (650 mg, quant.). It was.

The measurement data of the obtained compound 3 are shown below.
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.88 (t, J = 6.9 Hz, 3H), 0.91 (t, J = 7.3 Hz, 3H) 1.25-1.36 (m, 8H), 1.66 (sept, J = 6.0 Hz, 2H), 2.43 (s, 1H), 2.65 (t, J = 6.4 Hz, 2H), 6.60 (s, 1H), 7.26 (d, J = 8.4 Hz, 1H), 7.47 (s, 1H) 7.60 (d, J = 8.4 Hz, 1H), 7.95 (s, 1H),
¹³ C NMR (126 MHz, CDCl ₃ ); δ11.2, 14.5, 20.2, 23.4, 02325.8, 29.2, 32.7, 40.5, 41.3, 109.4, 124.4, 126.5, 127.0, 129.4 129.6, 133.8 (× 2), 137.8, 152.4; IR (KBr) ν 3411 cm ^-1 (OH);
EIMS (70 eV) m / z = 302 (M ⁺ ). HRMS (APCI) Calcd for C ₁₉ H ₂₆ O: 302.16989; Found: 302. 17023.

(Synthesis of 6- (2-ethylhexyl) -3-methylthio-2- (trifluoromethanesulfonyloxy) naphthalene (hereinafter, compound 4))
To a solution degassed by adding compound 3 (640 mg, 2.1 mmol) and pyridine (0.89 mL, 6.4 mmol) to dichloromethane (7 mL) was added trifluoromethanesulfonic anhydride (0.7 mL, 4.2 mmol) to 0. Added at ° C.
After stirring at room temperature for 25 minutes, the mixture was diluted with water (5 mL) and hydrochloric acid (4M, 2 mL), and extracted with dichloromethane (5 mL × 3).
The organic phase was washed with brine (5 mL × 3), dried over magnesium sulfate, and concentrated under reduced pressure to give a yellow oil, almost pure compound 4 (800 mg, 87%).

The measurement data of the obtained compound 4 are shown below.
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.87 (t, J = 7.2 Hz, 3H), 0.89 (t, J = 7.5 Hz, 3H) 1.24-1.36 (m, 8H), 1.67 (sept, J = 6.4 Hz, 2H), 2.59 (s, 3H), 2.67 (d, J = 7.0 Hz, 1H), 2.69 (d, d, J = 7.2 Hz, 1H), 7.32 (dd, J = 1.5, 8.4 Hz, 1H ), 7.54 (s, 1H),, 7.63 (s, 1H) 7.68 (s, 1H), 7.71 (d, J = 8.4 Hz, 1H),
¹³ C NMR (126 MHz, CDCl ₃ ); δ 11.1, 14.5, 16.2, 23.4, 25.8, 29.2, 32.7, 40.7, 41.4, 120.0, 120.3 (q, J = 315 Hz) 126.5, 126.7, 127.8, 129.2, 129.8, 130.0, 131.0, 133.2, 142.1, 145.2;
IR (KBr) ν1425, 1210 cm ^-1 (-O-SO _2- );
EIMS (70 eV), HRMS (APCI) Calcd for C ₂₀ H ₂₅ F ₃ O ₃ S ₂ : 434.11917; Found: 434.11905.

(Synthesis of trans-1- (3-methylthionaphthalen-2-yl) -2- (6- (2-ethylhexyl) -3-methylthionaphthalen-2-yl) ethene (hereinafter, compound 5))
Compound 4 (2.58 g, 5.94 mmol), 3-methylthio-2- (trifluoromethanesulfonyloxy) naphthalene (1.91 g, 5.94 mmol) and trans- were added to DMF (N, N-dimethylformamide) (48 mL). Pd (PPh ₃ ) ₄ (343 mg, 0.3 mmol, 5 mol%) was added to a solution degassed by adding 1,2-bis (tributylstannyl) ethylene (3.6 g, 5.94 mmol).
The mixture was heated at 90 ° C. in the dark for 24 hours. Then, it diluted with water and extracted with chloroform.
The extract was washed with brine, dried over magnesium sulfate and concentrated under reduced pressure.
The residue was passed through a silica gel pad (developing solvent: dichloromethane) to obtain a yellow solid compound 5 (910 mg, 32%).

The measurement data of the obtained compound 5 are shown below.
Mp 78-79 ° C;
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.88 (t, J = 7.1 Hz, 3H), 0.92 (t, J = 8.6 Hz, 3H), 1.24-1.38 (m, 8H), 1.67 (sept, J = 7.4 Hz, 1H), 2.60 (s, 1H), 2.69 (d, d, J = 6.7, 6.8 Hz, 2H), 7.27 (s, 1H), 7.44 (tt, J = 1.1, 7.5 Hz, 2H), 7.50 (s, 1H), 7.60 (s, 1H), 7.64 (s, 1H), 7.65 (s, 1H), 7.66 (d, J = 7.5 Hz, 1H), 7.74 (d, J = 8.3 Hz, 1H ), 7.77 (d, J = 8.3 Hz, 1H), 7.85 (d, J = 7.5 Hz, 1H), 8.06 (s, 1H), 8.09 (s, 1H);
¹³ C NMR (126 MHz, CDCl ₃ ); δ 11.2, 14.5, 16.7, 16.8, 23.4, 25.8, 29.3, 32.8, 40.8, 41.4, 124.3, 124.5, 125.3, 125.4, 126.0, 126.4, 126.8, 126.9, 128.0, 128.2, 128.3, 128.4, 129.1, 130.3, 131.9, 133.7, 133.8, 134.5, 135.4, 136.0, 136.2, 140.7;
EIMS (70 eV) m / z = 484 (M ⁺ ). HRMS (APCI) Calcd for C ₃₂ H ₃₆ S ₂ : 484.22529; Found: 484.22568.

(Synthesis of 2-2EH-DNTT)
Compound 5 (720 mg, 1.5 mmol) and iodine (11 g, 45 mmol) were added to chloroform (15 mL), and the mixture was stirred at 80 ° C. for 20 hours.
This mixture was added to aqueous sodium bisulfite (20 mL).
Thereafter, the mixture was extracted with chloroform, and the extract was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure.
The residue was washed with hexane to obtain 2-2EH-DNTT (186 mg, 28%) as a pale yellow solid.

The measurement data of the obtained 2-2EH-DNTT are shown below.
Mp> 300 ° C;
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.88 (t, J = 7.0 Hz, 3H), 0.92 (t, J = 7.4 Hz, 3H), 1.26-1.38 (m, 8H), 1.72 (sept, J = 6.4 Hz, 1H), 2.74 (d, d, J = 7.2, 7.1 Hz, 2H), 7.36 (d, J = 8.4 Hz, 1H) 7.52-7.54 (m, 2H), 7.67 (s, 1H), 7.94 (d, J = 8.4 Hz, 1H), 7.94-7.96 (m, 1H), 8.03-8.05 (m, 1H), 8.33 (s, 1H), 8.34 (s, 1H), 8.36 (s, 1H), 8.42 (s, 1H);
¹³ C NMR (126 MHz, CDCl ₃ ); δ 11.2, 14.5, 23.3, 25.9, 29.2, 32.8, 40.8, 41.2, 120.2, 120.3, 122.1, 122.7, 126.0, 126.2, 126.8, 127.7, 128.3, 128.4, 128.6, 130.2, 130.7, 131.6, 131.7, 132.0 (× 2), 132.8, 133.6, 134.2, 140.1, 141.1;
EIMS (70 eV) m / z = 452 (M ⁺ ). HRMS (APCI) Calcd for C ₃₀ H ₂₈ S ₂ : 452.16269; Found: 452.16248.

  As a comparative example, 2,9-di (2-ethylhexyl) dinaphtho [2,3-b: 2 ′, 3′-f] thieno [2,3-b] thiophene (stepwise as described below) Hereinafter, 2,9-EH-DNTT) was synthesized.

(Synthesis of trans-1,2-bis (6- (2-ethylhexyl) -3-methylthionaphthalen-2-yl) ethene (hereinafter, compound 6))
To a solution degassed by adding Compound 4 (1.48 g, 3.4 mmol) and trans-1,2-bis (tributylstannyl) ethylene to DMF (27 mL), Pd (PPh ₃ ) ₄ (158 mg, 0. 13 mmol, 4 mol%) was added.
The mixture was heated at 90 ° C. in the dark for 24 hours. Then, it diluted with water and extracted with chloroform.
The extract was washed with brine, dried over magnesium sulfate and concentrated under reduced pressure.
The residue was passed through a silica gel pad (developing solvent: dichloromethane) to obtain a yellow solid compound 11 (880 mg, 87%).

The measurement data of the obtained compound 6 are shown below.
Mp 64-65 ° C;
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.87 (t, J = 7.2 Hz, 6H), 0.90 (t, J = 7.4 Hz, 6H) 1.25-1.37 (m, 16H), 1.69 (sept, J = 6.1 Hz, 4H), 2.59 (s, 2H), 2.67 (d, J = 6.9 Hz, 4H), 2.69 (d, J = 7.1 Hz, 2H), 7.25 (d, J = 8.4 Hz, 2H), 7.49 ( s, 2H), 7.59 (s, 2H), 7.64 (s, 2H) 7.75 (d, J = 8.4 Hz, 2H), 8.01 (s, 2H),
¹³ C NMR (126 MHz, CDCl ₃ ); δ11.2, 14.5, 17.8, 23.4, 25.8, 29.3, 32.8, 40.8, 41.4, 124.3, 125.2, 126.4, 127.9, 128.2, 128.6, 130.4, 133.8, 134.6, 136.0 , 140.6;
EIMS (70 eV) m / z = 596 (M ⁺ ). HRMS (APCI) Calcd for C ₄₀ H ₅₂ S ₂ : 596.35049; Found: 596.35077.

(Synthesis of 2,9-EH-DNTT)
Compound 6 (2.2 g, 3.7 mmol) and iodine (28 g, 111 mmol) were added to chloroform (37 mL), and the mixture was stirred at 80 ° C. for 20 hours.
This mixture was added to aqueous sodium bisulfite (20 mL).
Thereafter, the mixture was extracted with chloroform, and the extract was washed with brine, dried over magnesium sulfate, and concentrated under reduced pressure.
The residue was washed with hexane to obtain 2,9-EH-DNTT (966 mg, 46%) as a pale yellow solid.

The measurement data of the obtained 2,9-EH-DNTT are shown below.
Mp 218-219 ° C;
¹ H NMR (500 MHz, CDCl ₃ ) δ 0.87 (t, J = 7.1 Hz, 6H), 0.92 (t, J = 7.5 Hz, 6H) 1.25-1.37 (m, 16H), 1.72 (sept, J = 6.0 Hz, 4H), 2.73 (d, J = 6.7 Hz, 2H), 2.74 (d, J = 7.1 Hz, 2H) 7.34 (d, J = 8.5 Hz, 2H), 7.65 (s, 2H), 7.92 (d , J = 8.5 Hz, 2H), 8.29 (s, 2H), 8.32 (s, 2H);
¹³ C NMR (126 MHz, CDCl ₃ ); δ 11.2, 14.5, 23.4, 25.9, 29.2, 32.8, 40.8, 41.3, 120.1, 122.1, 126.8, 128.3 (× 2), 130.2, 132.1, 133.7, 140.0, 141.1;
EIMS (70 eV) m / z = 564 (M ⁺ ). HRMS (APCI) Calcd for C ₃₈ H ₄₄ S ₂ : 594.28789; Found: 594.28815.

As a comparative example, 2-decyl-dinaphtho [2,3-b: 2 ′, 3] was prepared in the same manner as the synthesis of 2-2EH-DNTT, except that 2-ethylhexylmagnesium bromide was replaced with decylmagnesium bromide. '-F] thieno [2,3-b] thiophene (hereinafter, 2-D-DNTT) was synthesized.

(Synthesis of 2,9-D-DNTT)
As a comparative example, 2,9-didecyldinaphtho [2,3-b: 2 ′, 3] was prepared in the same manner as the synthesis of 2,9-EH-DNTT except that 2-ethylhexylmagnesium bromide was replaced with decylmagnesium bromide. '-F] thieno [2,3-b] thiophene (hereinafter, 2,9-D-DNTT) was synthesized.

(Evaluation of solubility)
2-2EH-DNTT, 2,9-EH-DNTT, 2-D-DNTT, and 2,9-D-DNTT were each dissolved in chloroform at room temperature, and the solubility was measured. The results are shown in Table 1.

  Compounds having a branched alkyl group (2-2EH-DNTT, 2,9-EH-DNTT) showed good solubility. On the other hand, it is clear that compounds having a linear alkyl group (2-D-DNTT, 2,9-D-DNTT) do not dissolve in a solvent and cannot be used as an organic semiconductor material for coating.

(Evaluation of thin film properties)
Thin films were prepared using 2-2EH-DNTT and 2,9-EH-DNTT, which had good solubility in solvents, and their physical properties were evaluated.

(Production and evaluation of 2-2EH-DNTT thin film and 2,9-EH-DNTT thin film)
2-2EH-DNTT was dissolved in chloroform to prepare a 0.3 g / L solution, filtered through a membrane filter, and then spin-coated on the surface-treated n-type silicon substrate to a thickness of about 100 nm. A 2-2EH-DNTT thin film was prepared. In addition, a 2,9-EH-DNTT thin film was prepared in the same manner as described above using 2,9-EH-DNTT.

  The absorption spectrum of the 2,9-EH-DNTT thin film is shown in FIG. In the absorption spectrum of a thin film of 2,9-EH-DNTT, dinaphtho [2,3-b: 2 ′, 3′-f] thieno [2,3-b] thiophene (hereinafter, DNTT) having no substituent As compared with the deposited film, a remarkable short wavelength shift is observed. This shows that the intermolecular interaction is weak in the thin film state.

  A photoelectron spectrum of the 2,9-EH-DNTT thin film is shown in FIG. The ionization potential of the 2,9-EH-DNTT thin film estimated from the photoelectron spectrum is 5.7 eV, which is larger than 5.4 eV of unsubstituted DNTT. This can be explained by the weak intermolecular interaction.

  Further, the out-of-plane X-ray diffraction result of the 2,9-EH-DNTT thin film is shown in FIG. Although a crystal peak can be seen in FIG. 1C, the estimated interlayer distance is as short as 16 angstroms, and the molecular orientation is not desirable.

  Subsequently, an absorption spectrum of the 2-2EH-DNTT thin film is shown in FIG. The absorption spectrum of the 2-2EH-DNTT thin film showed an absorption peak similar to that of DNTT, and a clear long wavelength shift was observed as compared with the 2,9-EH-DNTT thin film. This indicates that the intermolecular interaction in the thin film state is recovered as compared with the 2,9-EH-DNTT thin film.

A photoelectron spectrum of the 2-2EH-DNTT thin film is shown in FIG. The ionization potential in the thin film estimated from the photoelectron spectrum is 5.0 eV, which is lower than 5.4 eV of unsubstituted DNTT, and is similar to that of an asymmetric linear alkyl compound. Is suggested to exist.
Further, the out-of-plane X-ray diffraction result of the 2-2EH-DNTT thin film is shown in FIG. The peak observed by out-of-plane X-ray diffraction suggests that the crystal structure is oriented with the molecular long axis on the substrate surface, and the estimated interlayer distance is 26 Å, including alkyl groups. Corresponds to the length of the molecular long axis.

(Production and evaluation of transistor elements)
Using 2-2EH-DNTT and 2,9-EH-DNTT, which had good solubility as described above, bottom-gate transistor elements were fabricated and their characteristics were evaluated.

After thoroughly cleaning a highly doped n-type silicon substrate having a 200 nm thick silicon oxide film to be a gate electrode, the silicon oxide film surface of the n-type silicon substrate is perfluorodecyltriethoxysilane (FDTS). Silane-treated.
2-2EH-DNTT was dissolved in chloroform to prepare a 0.3 g / L solution, filtered through a membrane filter, and then spin-coated on the surface-treated n-type silicon substrate to a thickness of about 100 nm. A 2-2EH-DNTT thin film was prepared.
This thin film was heated at 200 ° C. for 30 minutes in a nitrogen atmosphere.
Gold was vacuum-deposited on the 2-2EH-DNTT thin film to form a source electrode and a drain electrode. In this manner, a bottom gate / top contact transistor element having a channel length of 50 μm and a channel width of 1.5 mm was produced. Hereinafter, this transistor element is referred to as a transistor element 2-2EH-DNTT.

  Further, using 2,9-EH-DNTT, a bottom gate / top contact transistor element was fabricated in the same manner as described above. Hereinafter, this transistor element is referred to as transistor element 2, 9-EH-DNTT.

Using 2-2EH-DNTT, changing the gate voltage Vg to 20 to -60 V and the source-drain voltage Vd to 0 to -60 V on the fabricated transistor element 2-2EH-DNTT It was measured. FIG. 3A shows transfer characteristics, and FIG. 3B shows output characteristics. From these characteristics, the mobility was calculated to be 0.3 cm ² / Vs.

  On the other hand, for the transistor element 2, 9-EH-DNTT, an attempt was made to measure the transistor characteristics in the same manner as described above, but it is clear that the transistor element 2, 9-EH-DNTT does not respond at all and does not behave as a transistor. became. The above-described physical property analysis of the 2,9-EH-DNTT thin film strongly suggests that the two ethylhexyl groups are sterically bulky, thus preventing dense molecular packing and significantly reducing intermolecular interactions. Yes. This also confirms that the transistor element 2, 9-EH-DNTT has no response, that is, the carriers injected into the thin film cannot move.

(Synthesis of 2- (3-ethylheptyl) dinaphtho [2,3-b: 2 ′, 3′-f] thieno [2,3-b] thiophene (hereinafter referred to as 2-3-3-EH-DNTT)
Except for using 3-ethylheptylmagnesium bromide instead of 2-ethylhexylmagnesium bromide, the synthesis of compound 1, synthesis of compound 2, synthesis of compound 3, synthesis of compound 4, synthesis of compound 5, In the same manner as the synthesis of 2-EH-DNTT, 2-3-3-EH-DNTT was synthesized.

The measurement data of the obtained 2-3-3-EH-DNTT are shown below.
mp> 300 ° C;
¹ H-NMR (500 MHz, CDCl ₃ ) δ 0.90 (t, J = 7.2 Hz, 3H), 0.92 (t, J = 6.6 Hz, 3H), 1.25-1.43 (m, 9H), 1.67-1.73 (m , 2H), 2.80 (t, J = 8.4 Hz, 2H), 7.40 (dd, J = 8.8 and 1.5 Hz, 1H), 7.52 (d, J = 6.7 Hz, 1H), 7.53 (d, J = 6.4 Hz , 1H), 7.71 (s, 1H), 7.94-7.97 (m, 1H), 7.96 (d, J = 8.8 Hz, 1H), 8.03-8.05 (m, 1H), 8.33 (s, 1H), 8.35 ( s, 1H), 8.36 (s, 1H), 8.43 (s, 1H);
¹³ C-NMR (126 MHz, CDCl ₃ ) 11.0, 14.2, 23.3, 26.2, 29.2, 33.1, 33.8, 35.2, 39.0, 120.1 (x3), 120.2, 121.9, 122.0, 122.5, 122.6, 125.5, 125.6, 125.8 ( x2), 126.0 (x2), 127.5, 127.7, 127.8, 128.4, 128.5, 130.2, 131.6, 131.7, 132.0, 132.1, 132.7, 133.5, 134.2, 141.0, 141.1, 141.4 (x2);
EI-MS (70 eV) m / z 466 (M ⁺ ); HR-MS (APCI) m / z calcd for C ₃₁ H ₃₁ S ₂ [M + H] ⁺ 467.18617, found 467.18637; Anal. Calcd for C ₃₁ H ₃₀ S ₂ C; 79.78, H; 6.48%. Found. C; 79.97, H; 6.46%.

(Evaluation of solubility)
2-3-3-EH-DNTT was dissolved in chloroform at room temperature, and the solubility was measured. The solubility of 2-3-3-EH-DNTT was 0.67 g / L, which was better than 2-2EH-DNTT (0.43 g / L).

(Production and evaluation of transistor elements)
Using 2-3-3-EH-DNTT, a bottom-gate / top-contact transistor element was fabricated and the characteristics were evaluated.
A highly doped n-type silicon substrate having a 200 nm thick silicon oxide film to be a gate electrode was sufficiently cleaned.
2-3EH-DNTT was dissolved in chloroform to prepare a 0.3 g / L solution, filtered through a membrane filter, and then spin-coated onto the surface-treated n-type silicon substrate. 2-3-3-EH-DNTT thin films were prepared.
This thin film was heated at 100 ° C. for 30 minutes in a nitrogen atmosphere.
Gold was vacuum-deposited on the 2-3-3-EH-DNTT thin film to form a source electrode and a drain electrode. In this way, a bottom-gate / top-contact transistor element (an integrated element) having a channel length of 40 μm and a channel width of 3 mm was produced.

After cleaning the n-type silicon substrate, the surface of the silicon oxide film is treated with silane with 1,1,1,3,3,3-hexamethyldisilazane (HMDS), and a bottom gate / top contact type transistor is formed as described above. An element (HMDS processing element) was produced.
After cleaning the n-type silicon substrate, the surface of the silicon oxide film was subjected to silane treatment with octadecyltrichlorosilane (ODTS) to produce a bottom gate / top contact transistor element (ODTS treatment element) in the same manner as described above.
Further, after cleaning the n-type silicon substrate, the silicon oxide film surface was treated with octyltrichlorosilane (OTS) to produce a bottom-gate / top-contact transistor element (OTS-treated element) in the same manner as described above.

For each of the fabricated transistor elements, the transistor characteristics were measured by changing the gate voltage Vg to 20 to −60 V and the source-drain voltage Vd to 0 to −60 V. Table 2 shows carrier mobility (μ [cm ² V ⁻¹ s ⁻¹ ]), threshold voltage (V _th [V]), and _{on / off} ratio (I _{on / off} ) of each transistor element. Further, FIG. 4A shows the transfer characteristics and FIG. 4B shows the output characteristics of a transistor element manufactured by silane treatment of the substrate with ODTS. In addition, 15 or more transistor elements are respectively produced, and the carrier mobility in Table 2 shows the average value and the maximum value (in parentheses).

In the transistor element manufactured by 2-3-3-EH-DNTT, the carrier mobility is improved as compared with the transistor element 2-2EH-DNTT. In particular, an ODTS element manufactured by subjecting a substrate to ODTS treatment had a maximum carrier mobility of 1.6 cm ² / Vs (average: 1.02 cm ² / Vs), and showed good transistor characteristics. This is probably because the ethyl group in the side chain of the ethyl heptyl group is separated from the DNTT skeleton, and the intermolecular interaction is increased.

  From the above results, the molecular design in which a branched alkyl group is introduced only into one naphthalene as in the compound represented by Formula 1 is indispensable to satisfy both the solubility in organic solvents and the transistor characteristics. It is believed that there is.

  It should be noted that the present invention can be variously modified and modified without departing from the scope of the present invention. Further, the above-described embodiment is for explaining the present invention, and does not limit the scope of the present invention.

  This application is based on Japanese Patent Application No. 2013-9153 filed on January 22, 2013 and Japanese Patent Application No. 2013-175678 filed on August 27, 2013. In the present specification, the specifications, claims and entire drawings of Japanese Patent Application No. 2013-9153 and Japanese Patent Application No. 2013-175678 are incorporated by reference.

  As described above, since the organic semiconductor material for solution process according to the present invention is excellent in solubility in a solvent, an organic semiconductor layer can be formed using a solution process such as a coating method, so that a semiconductor such as a field effect transistor can be formed. It can be used to manufacture the device.

Claims (8)

Including a compound represented by Formula 1,
(In Formula 1, Y ¹ and Y ² are each independently a chalcogen atom, one of R ¹ and R ² is a branched alkyl group, and the other is hydrogen.)
An organic semiconductor material for solution process. The main chain of the branched alkyl group is C3 or more,
The organic semiconductor material for solution processing according to claim 1. The main chain of the branched alkyl group is C6 or more,
The organic semiconductor material for solution processing according to claim 2. The side chain of the branched alkyl group is C2 or more,
The organic semiconductor material for solution process according to any one of claims 1 to 3. The side chain of the branched alkyl group is bonded to the carbon at the 2-position or more of the main chain,
The organic semiconductor material for solution processing according to any one of claims 1 to 4, wherein the organic semiconductor material is used for solution processing. The side chain of the branched alkyl group is bonded to the carbon at the 3-position or more of the main chain,
The organic semiconductor material for solution process according to claim 5. Y ¹ and Y ² are a sulfur atom or a selenium atom,
The organic semiconductor material for solution processing according to any one of claims 1 to 6, wherein the organic semiconductor material is used for solution processing. The organic semiconductor material for solution processing according to any one of claims 1 to 7,
An organic semiconductor device characterized by that.