KR100622026B1 - Insulator containing soluble polyimides and organic thin film transistor using them - Google Patents

Abstract

The present invention relates to an insulating film containing a soluble polyimide resin and an all-organic thin film transistor using the same, and more particularly, to an aromatic diamine containing a specific photosensitive enhancer, a diamine monomer containing a low polar group, and a specific tetracarboxylic acid. Soluble polyimide resin prepared by polymerizing dianhydride, containing a polyamic acid derivative, containing a new insulating film excellent in heat resistance, surface hardness, transparency and electrical insulation properties, and the new insulating film is deposited, the electric field effect The present invention relates to an all-organic thin film transistor with improved electric mobility.

Soluble polyimide resin, polyamic acid, insulating film, all organic thin film transistor

Description

Insulator containing soluble polyimides and organic thin film transistor using them}             

1 is an I-V (output) curve of an all organic thin film transistor device in which BPAA-1 prepared according to Example 1 of the present invention is introduced as a gate dielectric.

FIG. 2 is an I-V (transfer) curve of an all organic thin film transistor element having BPAA-1 prepared according to Example 1 of the present invention as a gate dielectric.

3 is an I-V (output) curve of an all-organic thin film transistor device having BPAA-3 prepared according to Example 3 of the present invention as a gate dielectric.

4 is an I-V (transfer) curve of an all-organic thin film transistor device in which BPAA-3 prepared according to Example 3 of the present invention is introduced as a gate dielectric.

5 is a cross-sectional view showing the structure of a top-contact device manufactured in an embodiment of the present invention.

The present invention relates to an insulating film containing a soluble polyimide resin and an all-organic thin film transistor using the same, and more particularly, to an aromatic diamine containing a specific photosensitive enhancer, a diamine monomer containing a low polar group, and a specific tetracarboxylic acid. Soluble polyimide resin prepared by polymerizing dianhydride, containing a polyamic acid derivative, containing a new insulating film excellent in heat resistance, surface hardness, transparency and electrical insulation properties, and the new insulating film is deposited, the electric field effect The present invention relates to an all-organic thin film transistor with improved electric mobility.

In general, the polyimide resin refers to a high heat resistant resin prepared by condensation polymerization of an aromatic tetracarboxylic acid or a derivative thereof with an aromatic diamine or an aromatic diisocyanate, followed by imidization.

The polyimide resin may have various molecular structures depending on the type of monomer used. As a typical aromatic tetracarboxylic acid component, pyromellitic dianhydride (PMDA) or nonphthalic anhydride (BPDA) is used, and as aromatic diamine component, para-phenylenediamine ( p- PDA) and meta-phenylenediamine ( m -PDA), 4,4-oxydianiline (ODA), 4,4-methylenedianiline (MDA), 2,2-bisaminophenylhexafuluropropane (HFDA), metabisaminophenoxydiphenylsulfone ( m- BAPS), parabisaminophenoxydiphenylsulfone ( p- BAPS), 1,4-bisaminophenoxybenzene (TPE-Q), 1,3-bisaminophenoxybenzene (TPE-R), 2, It is produced by polycondensation polymerization using aromatic diamines such as 2-bisaminophenoxyphenylpropane (BAPP) and 2,2-bisaminophenoxyphenylhexafuluropropane (HFBAPP).

Most polyimide resins are insoluble and insoluble ultra-high heat resistant resins, which include (1) excellent thermal oxidation resistance, (2) high usable temperature, and (3) long-term temperature of about 260 ° C and short-term temperature of about 480 ° C. It has characteristics such as excellent heat resistance, (4) radiation resistance, (5) excellent low temperature property, and (6) excellent chemical resistance.

Such aromatic polyimide resins have advantages of retaining excellent heat resistance characteristics, on the other hand, have high surface tension due to high polar group density, low dielectric constant, and the like, which are not easy to apply as an insulator for thin film transistors.

On the other hand, as an insulating material for thin film transistors, inorganic thin films having a high dielectric constant such as silicon nitride, barium strontium, and barium titanate are generally used. There is a disadvantage that expensive vacuum equipment is required for deposition. Thus, U.S. Patent No. 5,946,551 et al. Reported the result of forming an inorganic thin film from a precursor of an inorganic thin film by a chemical solution process at a relatively low temperature. In this case, however, a high process temperature of about 300 to 700 ° C. is required. The low temperature thinning process on plastic substrates such as polycarbonate, polysulfone, polyethersulfone, etc., which is limited to 200 ° C. or less, has a difficult disadvantage.

As one of the main characteristics of the insulator for high mobility of the thin film transistor, it is particularly required to minimize the interfacial tension with low polar organic semiconductor materials such as pentacene. There is a great demand for the development of new controlled organic materials.

Accordingly, the inventors of the present invention have made efforts to solve the problem of performing a thinning process of the insulating material used in the thin film transistor. As a result, specific soluble polyimide (SPI) resins and polyamic acid derivatives that have excellent solubility and photosensitivity, are capable of forming micropatterns by ultraviolet ancestors without using an initiator, and have excellent field effect charge mobility. The present invention has been completed by developing a novel polyimide insulating film having excellent electrical insulating properties by mixing a solution.

Accordingly, an object of the present invention is to provide a novel insulating film having excellent heat resistance, transparency and vertical alignment of liquid crystals, solubility and low surface tension and electrical insulation.

In addition, another object of the present invention is to provide an all-organic thin film transistor in which the insulating film is deposited to have excellent properties such as an electric field effect and can perform a low temperature process in a range of 150 to 180 ° C.

The present invention is characterized by an insulating film comprising a mixed composition of a soluble polyimide resin represented by the following formula (1) and a polyamic acid derivative represented by the following formula (2).

In Chemical Formula 1 or 2,

은

,

,

,

,

,

,

,

,

,

중에서 선택된 1종 또는 2종 이상의 4가기로서, 반드시 구조식 (a), (b), (c), (d) 및 (e) 중에서 선택된 1종 또는 2종 이상의 지방족 고리계 4가기를 포함하며; 및

silver

,

,

,

,

,

,

,

,

,

One or two or more tetravalent groups selected from the group consisting of at least one aliphatic ring system tetravalent group selected from the structural formulas (a), (b), (c), (d) and (e); And

및

는 각각

,

,

,

,

,

,

,

,

,

,

및

(이때, n은 1 내지 30 범위의 자연수) 중에서 선택된 1종 이상의 2가기로서, 반드시 상기

는 상기 구조식 (f)의 알킬숙시닉이미드 측쇄를 가지는 방향족 2가기를 포함하며;

And

Are each

,

,

,

,

,

,

,

,

,

,

And

Wherein n is a natural number in the range of 1 to 30.

Comprises an aromatic divalent group having an alkylsuccinimide side chain of formula (f);

L and m each represent a natural number ranging from 1 to 300.

In addition, the present invention has another feature of an all-organic thin film transistor prepared by depositing the above insulating film.

Referring to the present invention in more detail as follows.

The present invention is a novel polyimide insulating film suitable for an all organic thin film transistor by mixing a soluble polyimide resin represented by the formula (1) and a polyamic acid derivative represented by the formula (2), and an all organic thin film transistor using the insulating film It is about.

The soluble polyimide resin represented by the formula (1) is a novel soluble polyimide resin developed by the present inventors, and has a structural feature having a low polar alkylsuccinic imide group and a specific aliphatic ring group at the same time as a side chain group. Application No. 04-43766.

The soluble polyimide resin represented by Chemical Formula 1 and the polyamic acid derivative represented by Chemical Formula 2 according to the present invention are prepared by condensation polymerization of an aromatic tetracarboxylic acid or a derivative thereof and an aromatic diamine or an aromatic diisocyanate. Depending on the type can have several molecular structures. Generally, aromatic tetracarboxylic acid monomers include pyromellitic dianhydride (PMDA), benzophenone tetracarboxylic dianhydride, oxydiphthalic dianhydride, nonphthalic dianhydride (BPDA) and hexafluoroisopropylidene diphthalic acid. It selects and uses from anhydrides. And, as the aromatic diamine monomer, generally para-phenylenediamine ( p- PDA), meta-phenylenediamine ( m- PDA), 4,4-oxydianiline (ODA), 4,4-methylenedianiline (MDA) ), 2,2-bisaminophenylhexafluoropropane (HFDA), metabisaminophenoxydiphenylsulfone ( m- BAPS), parabisaminophenoxydiphenylsulfone ( p- BAPS), 1,4-bisamino Phenoxybenzene (TPE-Q), 1,3-bisaminophenoxybenzene (TPE-R), 2,2-bisaminophenoxyphenylpropane (BAPP), 2,2-bisaminophenoxyphenylhexafulo It is selected and used from roperopan (HFBAPP).

The soluble polyimide resin represented by the formula (1) or the polyamic acid derivative represented by the formula (2) forming the polyimide insulating film according to the present invention is represented by the structural formulas (a) to (e) in addition to the general aromatic monomers described above. It is prepared using an aliphatic tetracarboxylic dianhydride monomer and a diamine monomer containing an aromatic diamine substituted with the alkyl succinimide group represented by the formula (f) as an essential component.

That is, the soluble polyimide resin represented by the formula (1) or the polyamic acid derivative represented by the formula (2) is an acid dianhydride monomer, 1,2,3 as an aliphatic tetracarboxylic dianhydride monomer in addition to the usual aromatic tetracarboxylic acid monomer. , 4-cyclobutane tetracarboxylic dianhydride [CBDA; (a)], 1,2,3,4-cyclopentane tetracarboxylic dianhydride [CPDA; (b)], 5- (2,5-dioxotetrahydrofuryl) -3-methylcyclohexane-1,2-dicarboxylic dianhydride [DOCDA; (c)], 4- (2,5-dioxotetrahydrofuryl-3-yl) -tetraline-1,2-dicarboxylic dianhydride [DOTDA; (d)], and bicyclooctene-2,3,5,6-tetracarboxylic dianhydride [BODA; (e)] one or two or more aliphatic tetracarboxylic dianhydride selected from among the essential components. At this time, the aliphatic tetracarboxylic dianhydride represented by the structural formulas (a) to (e) is used in the range of 1 to 99 mol% based on the total amount of the acid dianhydride monomers.

The soluble polyimide resin represented by Chemical Formula 1 has a structural feature in which an alkyl succinimide group is simultaneously bonded with an aliphatic ring group as a side chain group, and as a diamine monomer, the structural formula (f) It is prepared by including an aromatic diamine substituted with an alkyl succinimide group represented by the essential component as an essential component. At this time, the aromatic diamine represented by the structural formula (f) is used in the range of 1 to 99 mol% based on the total amount of the diamine monomer.

Thus, the novel mixture prepared by using the aromatic diamine represented by the above (f) as an essential monomer component has transparency by mixing a polyamic acid and a soluble polyimide resin having a succinimide side chain substituted with a low polar alkyl group. In addition, the printability and mechanical properties are improved, and in particular, the electrical insulating properties are excellent, and thus the use as an insulating film for an organic thin film transistor is expected.

The soluble polyimide resin represented by Formula 1 prepared by condensation polymerization and imidization with the monomer composition as described above has a weight average molecular weight (Mw) of 5,000 to 150,000 g / mol, an intrinsic viscosity range of 0.1 to 1.5 dL / g, It has the characteristic of glass transition temperature range 150-300 degreeC. In addition, the soluble polyimide resin represented by Formula 1 is aprotic polarity such as dimethylacetamide (DMAc), dimethylformamide (DMF), N -methyl-2-pyrrolidone (NMP), acetone, ethyl acetate Easily dissolved at room temperature with respect to organic solvents such as meta-cresol, including the solvent. In particular, low solubility solvents such as tetrahydrofuran (THF), chloroform and low absorption solvents such as gamma-butyrolactone exhibit high solubility of 10% by weight or more at room temperature. Moreover, high solubility is shown also about these mixed solvents. Such soluble polyimide resins are in the range of 35 to 45 dyne / cm in surface tension and in the range of 3 to 5 in the dielectric constant.

In addition, the polyamic acid derivative represented by Chemical Formula 2 has an aliphatic tetracarboxylic dianhydride represented by the structural formulas (a) to (e) as an essential monomer as an acid dianhydride monomer to improve mechanical properties and minimize heat resistance reduction. At the same time, it was possible to prepare a polyamic acid derivative having improved printability. Polyamic acid derivative represented by the formula (2) prepared by solution polymerization in the composition of the monomer is a weight average molecular weight (Mw) range 10,000 ~ 200,000 g / mol, intrinsic viscosity range 0.3 ~ 2.0 dL / g, glass transition temperature range 200 It has the characteristic of -400 degreeC and imidation temperature range 130-300 degreeC. In addition, the polyamic acid derivative represented by Formula 2 is an aprotic polar solvent such as dimethylacetamide (DMAc), dimethylformamide (DMF), N -methyl-2-pyrrolidone (NMP), acetone, ethyl acetate In addition, the organic solvent such as meta-cresol has a characteristic that is easily dissolved at room temperature. In particular, low solubility solvents such as tetrahydrofuran (THF), chloroform and low absorption solvents such as gamma-butyrolactone exhibit high solubility of 10% by weight or more at room temperature. Moreover, high solubility is shown also about these mixed solvents.

The insulating film for an all-organic thin film transistor of the present invention is prepared by dissolving a soluble polyimide resin represented by the formula (1) and a polyamic acid derivative represented by the formula (2) having the characteristics of monomer composition as described above in a solvent. In this case, in addition to the above-described soluble polyimide resin and polyamic acid derivative, various additives for improving the physical properties of the insulating film may be further mixed and used within the scope of the present invention.

On the other hand, after fabricating an all-organic thin film transistor from the soluble polyimide resin represented by the formula (1) and the polyamic acid derivative represented by the formula (2) according to the present invention, the electro-optical characteristics of the all-organic thin film transistor device is evaluated The dielectric breakdown voltage was in the range of 3-7 MV / cm. In addition, it was found that the dielectric constant of 3 to 6 and the surface tension were in the range of 35 to 45 dyne / cm at a frequency of 10 KHz, and 10 to 50 by irradiation with ultraviolet light having a wavelength of 300 to 400 nm. It was shown that it is possible to form a micro pattern of μm.

As described above, the polyamic acid mixed composition containing the soluble polyimide resin according to the present invention is excellent in solubility and thus has a plastic substrate such as polycarbonate, polysulfone polyether sulfone, or the like. In addition to the low-temperature process is possible, the introduction of a low polar side chain group, in particular, is a novel polymer material with improved surface properties and electrical insulation properties.

Such a present invention will be described in more detail based on the following examples, but the present invention is not limited thereto.

Preparation Example 1 Preparation of 1- (3,5-dinitrophenyl) -3- (1-octadecene) -succinicimide (DN-IM-18)

While slowly passing nitrogen gas through a 250 mL reactor equipped with a stirrer and a nitrogen injector, 9.2 g (0.05 mole) of 3,5-dinitroaniline was dissolved in 50 mL of acetic acid as a reaction solvent, and then passed through nitrogen gas. 9.1 g (0.05 mole) of 2-octadecen-1-yl succinic anhydride was added and refluxed for 24 hours. After the reaction solution was cooled to room temperature, a precipitated solid was obtained. The obtained solid was recrystallized in methanol to prepare 1- (3,5-dinitrophenyl) -3- (1-octadecene) -succinimide (DN-IM-18) (yield 63%).

Preparation Example 2 Preparation of 1- (3,5-diaminophenyl) -3-octadecyl-succinicimide (DA-IM-18)

After dissolving 10.3 g (0.02 mole) of DN-IM-18 obtained in Preparation Example 1 in 100 mL of NMP and ethanol (1/3 volume ratio), Pd / C (5%) catalyst (metal on the surface of the carbon particles) 0.5 g of palladium applied in an amount of 5%) was added to a hydrogen reactor, followed by reduction for 2 hours at 60 ° C. After filtering the reaction mixture, the reaction solvent was distilled under reduced pressure. 6.87 g of 1- (3,5-diaminophenyl) -3-octadecyl-succinimide (DA-IM-18) was prepared by recrystallization in hexane / ethyl acetate cosolvent (yield 75%).

The obtained DA-IM-18 is a diamine monomer having a succinimide side chain substituted with a low polar alkyl group, and it can be confirmed that the yield after recrystallization can be prepared at 50% or more, and also excellent storage in air. Stability was shown.

Preparation Example 3 Preparation of Polyamic Acid (CPAA)

19.8 g (0.1 mole) of methylene dianiline was dissolved in the reaction solvent N-methyl-2-pyrrolidone while slowly passing nitrogen gas through a 500 mL reactor equipped with a stirrer and a nitrogen injection device, and then passed through nitrogen gas. 19.6 g (0.1 mole) of 1,2,3,4, -cyclopentanetetracarboxylic anhydride in solid phase was slowly added. At this time, the solid content (solid content) was fixed to 15% by weight, and stirred for 36 hours while maintaining the reaction temperature below 0 ℃ to obtain a polyamic acid solution (CPAA).

Preparation Example 4 Preparation of Soluble Polyimide Resin (SPI)

1- (3,5-diaminophenyl) -3-octadecyl-succinate obtained in Preparation Example 2 while slowly passing nitrogen gas into a 250 mL reactor equipped with a stirrer, a temperature controller, a nitrogen injection device, and a cooler. 9.15 g (0.02 mole) of nickimide (DA-IM-18) was dissolved in the reaction solvent N-methyl-2-pyrrolidone, and then passed through nitrogen gas to solid dioxotetrahydrofuryl-3-methylcyclo 5.28 g (0.02 mole) of hexane-1,2-dicarboxylic dianhydride was added slowly. At this time, the solid content (solid content) was fixed to 20% by weight, and stirred for 24 hours while maintaining the reaction temperature below 0 ℃ to obtain a polyamic acid solution (SPI). 6.12 g (0.06 mole) of acetic anhydride and 0.1 g (0.1 mole) of pyridine were added to the polyamic acid solution, and the mixture was stirred at room temperature for 24 hours, stirred at 120 ° C. for 3 hours, and then washed with methanol several times. Mid (SPI) was obtained.

Example 1 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-1).

50 g of the polyamic acid solution obtained in Preparation Example 3 and 0.15 g of the soluble polyimide obtained in Preparation Example 4 were gradually passed while passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 80 g of 2-pyrrolidone, 120 g of gamma -butylolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 2 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-2).

50 g of the polyamic acid solution obtained in Preparation Example 3 and 0.4 g of the soluble polyimide obtained in Preparation Example 4 were slowly mixed with nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 80 g of methyl-2-pyrrolidone, 120 g of gamma -butyrolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 3 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-3)

50 g of the polyamic acid solution obtained in Preparation Example 3 and 0.8 g of the soluble polyimide obtained in Preparation Example 4 were slowly passed while passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 80 g of methyl-2-pyrrolidone, 120 g of gamma -butyrolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 4 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-4)

50 g of the polyamic acid solution obtained in Preparation Example 3 and 3.2 g of the soluble polyimide obtained in Preparation Example 4 were slowly passed while passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 75 g of methyl-2-pyrrolidone, 120 g of γ-butylolactone, and 60 g of 2-n-butoxyethanol were added thereto, and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 5 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-5)

50 g of the polyamic acid solution obtained in Preparation Example 3 and 7.5 g of the soluble polyimide obtained in Preparation Example 4 were gradually passed while passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 75 g of methyl-2-pyrrolidone, 120 g of γ-butylolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 6 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-6)

50 g of the polyamic acid solution obtained in Preparation Example 3 and 1.75 g of the soluble polyimide obtained in Preparation Example 4 were gradually passed while passing nitrogen gas through a 1000 v reactor equipped with a stirrer and a nitrogen injector. 75 g of methyl-2-pyrrolidone, 120 g of gamma -butyrolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Example 7 Preparation of Soluble Polyimide and Polyamic Acid Mixture (BPAA-7)

50 g of the polyamic acid solution obtained in Preparation Example 3 and 6.75 g of the soluble polyimide obtained in Preparation Example 4 were gradually passed while passing nitrogen gas slowly through a 1000 mL reactor equipped with a stirrer and a nitrogen injector. 75 g of methyl-2-pyrrolidone, 120 g of γ-butylolactone, and 60 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Comparative Example 1: Preparation of Soluble Polyimide Solution

While slowly passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injector, 52 g of N-methyl-2-pyrrolidone (3 g) of the soluble polyimide (SPI) resin obtained in Preparation Example 4 was diluted. , 52 g of γ-butylolactone and 26 g of 2-n-butoxyethanol were stirred for 24 hours to prepare a solution having a viscosity of 20 cps.

Comparative Example 2: Preparation of Polyamic Acid Solution

While slowly passing nitrogen gas through a 1000 mL reactor equipped with a stirrer and a nitrogen injection device, 20 g of the polyamic acid (CPAA) solution obtained in Preparation Example 3 was 34 g of N-methyl-2-pyrrolidone, 50 g of γ-butylolactone and 25 g of 2-n-butoxyethanol were added and stirred for 24 hours to prepare a solution having a viscosity of 25 cps.

Experimental Example 1 Measurement of Properties of Thin Films

The thin films were prepared by spin coating the solutions prepared according to Examples 1 to 7 and Comparative Examples 1 to 2 to a thickness of 0.05 to 0.2 μm on an ITO glass plate, and then thermosetting at a temperature of 230 ° C. for 30 minutes. The physical properties of the thin film prepared as described above are shown in Table 1 below.

division Composition Thin Film Properties Polyimide (% by weight) Polyamic acid (% by weight) Intrinsic viscosity ^*) (dL / g) MDT (℃) RW (%) Surface tension (dyne / cm) Pencil hardness Example 1 (BPAA-1) SPI CPAA 0.98  492 43 39.5 H Example 2 (BPAA-2) SPI CPAA 0.95  488 37 36.2 2H Example 3 (BPAA-3) SPI CPAA 0.91  484 34 36.1 2H Example 4 (BPAA-4) SPI CPAA 0.72  476 29 35.5 2H Example 5 (BPAA-5) SPI CPAA 0.54  476 25 35.2 2H Example 6 (BPAA-6) SPI CPAA 0.82  476 23 35.2 2H Example 7 (BPAA-7) SPI CPAA 0.64 472 20 35.0 2H Comparative Example 1 (SPI) SPI - 0.11  492 14 35.4 B Comparative Example 2 (CPAA) - CPAA 1.00  496 44 44.6 B *): Measured at 30 ° C with a concentration of 0.5 g / dL using NMP as a solvent

As shown in Table 1, the intrinsic viscosity of Comparative Example 1 containing the soluble polyimide resin alone component was 0.11 dL / g, the intrinsic viscosity of Comparative Example 2 containing the polyamic acid alone component was 1.0 dL / g, these It was confirmed that all were bright amber transparent resins. In addition, the resin of Comparative Example 1 and Comparative Example 2 was found to be very excellent in the film forming and mechanical properties by the solvent casting.

On the other hand, according to the present invention, the composition containing the soluble polyimide resin and the polyamic acid derivative was found to maintain the intrinsic viscosity in the range of 0.54 to 0.98, excellent mechanical properties, especially pencil hardness of the polyimide thin film H Surface hardness was remarkably improved compared with Comparative Example 1 and Comparative Example 2 in the order of -2H. In addition, the thin film prepared using this composition showed a tendency to decrease with increasing content of the diamine into which the succinimide side chain group having the imide ring-containing ring side chain group was introduced in the surface tension. Surface tensions in the dyne / cm range are shown.

Experimental Example 2 Preparation and Characterization of Polyimide Thin Films

After spin coating the soluble solutions prepared in Examples 1 to 7 and Comparative Examples 1 to 2 to form a thin film having a thickness of 3000 to 5000 Pa, heat treatment at 90 ° C. for 2 minutes to remove the solvent, followed by 150 to 210 ° C. Dry at temperatures between 1 to 60 minutes.

1. Characterization of Organic Insulator: Dielectric Constant

In order to evaluate the electrical insulation properties of the thin films prepared in Examples 1 to 7 and Comparative Examples 1 and 2, a simple device having a gold electrode-polyimide thin film-gold electrode (MIM) structure was fabricated on glass and plastic substrates. The same conditions were produced through vacuum deposition and spin coating.

In order to measure the dielectric constants of the polyimide thin films prepared from Examples 1 to 7 and Comparative Examples 1 and 2, 40 nm thick gold was thermally deposited on a glass substrate under a vacuum of about 6 to 10 torr. Here, the polyamic acid (PAA) solution was spin-coated and thinned to a thickness of 3000 to 5000 Pa, and then heat-treated at 90 ° C. for 2 minutes to remove the solvent. Subsequently, ultraviolet rays of 100 to 5000 mJ were irradiated with a mercury lamp, and then partial imidization reaction was performed for 1 to 60 minutes at a temperature between 90 and 150 ° C.

The photo-thermally cured polyimide film is immersed in a 2.38% by weight aqueous solution of tetramethylammonium hydroxide (TMAH) to remove the non-exposed sites, and then heat-treated at a temperature of 200 to 300 ° C. for 1 to 180 minutes. The dehydration reaction was completed.

After depositing a thin film of gold with a diameter of 2 cm on the polyimide thin film obtained above to a thickness of 40 nm, the dielectric constant was calculated by measuring the capacitance at a frequency of 1 MHz using an impedance analyzer. Dielectric constant and surface tension measurement results are shown in Table 2 below.

Polyamic acid derivatives Dielectric Constant (at 10 kHz) Surface tension (dyne / cm) Example 1 (BPI-1) 3.49 42.5 Example 2 (BPI-2) 3.45 40.2 Example 3 (BPI-3) 3.33 39.7 Example 4 (BPI-4) 3.20 38.9 Example 5 (BPI-5) 3.15 36.5 Example 6 (BPI-6) 3.51 45.0 Example 7 (BPI-7) 3.50 47.0 Comparative Example 1 (SPI) 2.50 35.0 Comparative Example 2 (CPAA) 3.68 50.0

As shown in Table 2, the polyimide resins prepared according to Examples 1 to 7 according to the present invention had a dielectric constant in the range of 3.15 to 3.51 and a surface tension in the range of 36.5 to 47.0 dyne / cm, As the content of DA-L-18IM, a monomer containing an octadecyl side group, increased, both dielectric constant and surface tension decreased.

2. Fabrication and Characterization of Organic Thin Film Transistor

The organic thin film transistor was produced using the photocured polyimide of this invention, and the characteristic was measured.

As an organic semiconductor, pentacene, which is widely used in organic thin film transistors and has a relatively good performance, was used. Substrates used plastic substrates such as glass and polyethersulfone.
FIG. 5 illustrates a structure of a phase contact device, and a method of manufacturing the top-contact device is as follows.

delete

First, since substrate cleanliness is one of the most important factors when manufacturing electronic devices, the ultrasonic cleaning using detergent, distilled water, acetone, and isopropyl alcohol was used, followed by drying sufficiently in an oven, and the plastic substrate 2 was commercially available. After detaching only the protective film without a separate washing process, it was used as it is. On the well cleaned substrate, gold was first thermally vacuum deposited in a vacuum of 1 × 10 ⁻⁶ torr using a shadow mask to form a 2 mm wide gate electrode 1 having a thickness of 40 nm. The photocurable polyamic acid solution of the present invention thereon is spin-coated to 300 nm thickness, dried at 90 ° C. for 2 minutes, irradiated with ultraviolet light at 365 nm and partially imidized at a temperature of 90-150 ° C. It was then developed with a 2.38% by weight aqueous tetramethylammonium hydroxide solution and patterned to the desired shape. Next, the polyimide insulating film was obtained by heating at 200-300 degreeC. Pentacene (6), an organic semiconductor, was deposited on the polyimide insulating film (3) to a thickness of 50 nm using thermal vacuum deposition in a vacuum of 1 × 10 ⁻⁶ torr. At this time, the temperature of the substrate having a great influence on the crystallization of pentacene was kept constant at 90 ℃. Finally, gold was deposited to a thickness of 40 nm in the same manner as the gate deposition to form the source and drain electrodes 4 and 5.

Bottom-contact devices were fabricated by changing the order of formation of pentacene, source, and drain electrodes.

The characteristics of the device manufactured as described above were measured in the saturation region by measuring the drain voltage-drain current according to the gate voltage and the gate voltage-drain current curve according to the drain voltage using an E5272 device manufactured by Agilent Technologies. Various characteristics were evaluated using the current and voltage equations.

In Equation 1, V T is a threshold voltage, Vgs is an applied gate voltage, μ is a field effect charge mobility, W and L are channel width and length, and C is capacitance of an insulating film.

와 Vgs의 그래프로부터 Ids 가 0인 게이트 전압으로 결정되고, 전계효과 전하이동도는

와 Vgs의 그래프의 기울기로부터 산출하였다. 도 1 ∼ 4는 각각 실시예 1(BPAA-1)과 실시예 3(BPAA-3)을 게이트 유전체로 도입하여 제조한 전유기 박막트랜지스터 소자의 게이트 전압에 따른 드레인 전압-드레인 전류 및 드레인 전압에 따른 게이트 전압-드레인 전류 곡선들을 측정하여 나타낸 것이다.
이외에도 실시예 1 ∼ 7 및 비교예 1 ∼ 2로 부터 제조된 유기박막 트랜지스터의 특성을 정리하여 그 결과를 다음 표 3에 나타내었다. Threshold voltage

From the graphs of and Vgs, Ids is determined as the gate voltage with zero, and the field effect charge mobility is

Calculated from the slope of the graph of and Vgs. 1 to 4 show drain voltages, drain currents, and drain voltages according to gate voltages of the organic thin film transistor elements manufactured by introducing Example 1 (BPAA-1) and Example 3 (BPAA-3) into the gate dielectric, respectively. The measured gate voltage-drain current curves are shown.
In addition, the characteristics of the organic thin film transistors manufactured from Examples 1 to 7 and Comparative Examples 1 to 2 are summarized and the results are shown in Table 3 below.

Polyamic acid derivatives Field Effect Charge Mobility (cm ² / Vs) Off current (A) On / Off ratio Threshold Voltage (V) Subthreshold Swing (V / dec) Example 1 (BPI-1) 4.84 1.6 × 10 ^-9 3 × 10 ⁴ -2.5 0.5 Example 2 (BPI-2) 4.30 6.5 × 10 ^-10 4.7 × 10 ⁴ -2.6 0.7 Example 3 (BPI-3) 3.13 5.0 × 10 ^-10 7 × 10 ⁴ -3.0 0.5 Example 4 (BPI-4) 4.50 5.0 × 10 ^-10 2 × 10 ⁵ -3.5 0.9 Example 5 (BPI-5) 5.00 3.0 × 10 ^-12 5 × 10 ⁵ -3.0 0.7 Example 6 (BPI-6) 5.07 4.0 × 10 ^-12 7 × 10 ⁵ -2.5 0.6 Example 7 (BPI-7) 7.05 2.0 × 10 ^-12 7 × 10 ⁵ -2.0 0.8 Comparative Example 1 (SPI) 0.5 1.0 × 10 ^-9 2 × 10 ⁴ -8.0 3.0 Comparative Example 2 (CPAA) 1.34 1.0 × 10 ^-9 1 × 10 ⁴ -5.5 2.0

As shown in Table 3, the insulating film of Examples 1 to 7 containing DA-L-18IM according to the present invention compared to the insulating film of Comparative Example 1 and Comparative Example 2 that does not contain DA-L-18IM Field effect charge mobility, off current, threshold voltage, on / off ratio, subthreshold swing (V / dec), etc. You can see that the performance is greatly improved.

In summary, Experimental Example 1 and Experimental Example 2, the polyimide resin according to the present invention has a weight average molecular weight (Mw) of 10,000 to 200,000 g / mol range, intrinsic viscosity of 0.05 to 2.0 g / dL range, thermal decomposition temperature of 380 ~ 450 ℃ Range, dielectric constant 3-6 range at 10 KHz, surface tension 35-45 dyne / cm range. The overall characteristics of the organic thin film transistor fabricated using the organic insulating film of the present invention were improved, in particular, the field effect mobility was greatly improved, and the charge mobility was in the range of 3.0 to 10.0 cm 2 / Vs. .

As indicated above, the present invention is composed of a mixed composition of a soluble polyimide resin represented by the formula (1) and a polyamic acid solution represented by the formula (2), low temperature process characteristics in the range of 130 ~ 250 ℃, excellent electrical properties, By retaining chemical resistance and heat resistance, not only the application as an insulator material for transistors applied to all-organic display devices is possible, but also the effect of shortening the complicated process of manufacturing the liquid crystal display device can be shortened.

Claims (10)

delete A soluble polyimide resin represented by the following formula (1) and a polyamic acid derivative represented by the following formula (2) comprises a mixed composition comprising a mixing ratio of 1 to 99% by weight: 1 to 99% by weight, The polyimide resin and the polyamic acid derivative may be one or two or more aliphatic ring-based tetravalent groups selected from the following structural formulas (a), (b), (c), (d) and (e), and the following structural formulas An insulating film characterized by having a structure in which an aromatic divalent group having an alkylsuccinimide side chain of (f) is necessarily contained: [Formula 1]

[Formula 2]

In Chemical Formula 1 or 2,

silver

,

,

,

,

,

,

,

,

,

And

One or two or more tetravalent groups selected from the group consisting of at least one aliphatic ring system tetravalent group selected from the structural formulas (a), (b), (c), (d) and (e); And

And

Are each

,

,

,

,

,

,

,

,

,

,

, And

Wherein n is a natural number in the range of 1 to 30.

Comprises an aromatic divalent group having an alkylsuccinimide side chain of formula (f); L and m each represent a natural number ranging from 1 to 300. The insulating film according to claim 2, wherein the intrinsic viscosity of the soluble polyimide resin represented by Chemical Formula 1 is in the range of 0.1 to 1.5 dL / g, and the weight average molecular weight is in the range of 5,000 to 150,000 g / mol. The soluble polyimide resin represented by Formula 1 is dimethylacetamide, dimethylformamide, N -methyl-2-pyrrolidone, tetrahydrofuran, chloroform, acetone, ethyl acetate and gamma-butyro. An insulating film, characterized in that it has a dissolution property for a solvent selected from lactones. 3. The insulating film according to claim 2, wherein the intrinsic viscosity of the polyamic acid derivative represented by Chemical Formula 2 is in the range of 0.3 to 2.00 dL / g, and the weight average molecular weight of the polyamic acid derivative is in the range of 10,000 to 200,000 g / mol. The insulating film according to claim 2, wherein the imidation temperature range of the polyamic acid derivative represented by Chemical Formula 2 is 130 to 300 ° C. An all-organic thin film transistor, characterized in that manufactured by depositing the insulating film of any one of the claims 2 to 6. 8. The thin film transistor of claim 7, wherein the insulating film is deposited in a thickness range of 30 to 500 nm. The organic active layer of claim 7, further comprising depositing one or two or more compounds selected from pentacene, metal petalocyanine, polythiophene, polyphenylenevinylene, and derivatives thereof on the upper surface of the insulating film. An all-organic thin film transistor, characterized in that forming. 8. The organic thin film transistor of claim 7, wherein the organic thin film transistor maintains a field mobility of 0.1 to 10 cm 2 / Vs.

Images