JP2009295420A - Flexible organic electroluminescence device - Google Patents

Abstract

To provide an image display device and a flexible transparent organic electroluminescence device having a flexible polyimide film with high light transmittance, high heat resistance, high toughness and low water absorption.
An image display device using a polyimide film containing at least 10 mol% or more of a repeating unit represented by formula [1] as an optical film, and at least 10 mol% of a repeating unit represented by formula [1]. The transparent organic electroluminescent element provided with the board | substrate which consists of a polyimide film contained above.

Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. Represents a cycloalkyl group having 3 to 7 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.)
[Selection figure] None

Description

  The present invention relates to an image display device and a flexible transparent organic electroluminescence element. More specifically, the present invention relates to an image display device and an organic electroluminescence element using a flexible polyimide film having an alicyclic structure.

Conventionally, glass has been used for electrical insulating films, organic electroluminescence (hereinafter abbreviated as organic EL) display substrates, liquid crystal display substrates, electronic paper substrates, and solar cell substrates in various electronic devices.
However, recently, with the increase in screen size of these devices, the problem of weight increase due to the use of glass substrates, and mobile information communication devices such as mobile information terminals such as mobile phones, electronic notebooks, laptop computers, etc. As the display device becomes thinner, the problem of breakage of the glass substrate has become serious.

Accordingly, there is a demand for the use of a plastic substrate that is lighter and more flexible, has impact resistance, and can be easily molded.
A transparent, flexible and tough plastic substrate makes it possible to realize a flexible display panel that can be bent and rolled.
In the organic EL display substrate field, an example using polyethylene naphthalate (PEN) is known (Patent Document 1). The heat resistant temperature of PEN is 150 ° C., and low-temperature film formation is required, but the practical manufacturing method has not yet been established.

By the way, since polyimide resin has high mechanical strength, heat resistance, insulation, and solvent resistance, it is widely used as a thin film for electronic materials such as protective materials, insulation materials, and color filters in liquid crystal display elements and semiconductors. It has been.
However, since the conventional wholly aromatic polyimide resin is colored with a deep amber color, a problem arises in thick films in the field of electronic devices that require high transparency.
As one method to realize transparency, if a polyimide precursor is obtained by polycondensation reaction between an alicyclic tetracarboxylic dianhydride and an aromatic diamine, the precursor is imidized to produce a polyimide, and then a comparison. It is known that a highly transparent polyimide can be obtained with less chromatic coloring (Patent Document 2).

  However, 3,5,6-tricarboxy-2-carboxymethylnorbornane-2: 3,5: 6-dianhydride (hereinafter abbreviated as NDA) represented by the formula [5] and the formula [6] NDA-BAPB polyimide obtained by polycondensation with a substituted bis (aminophenoxy) benzene compound (hereinafter abbreviated as BAPB) represented by the formula is not specifically described in Patent Document 2, and its physical properties are unknown. In addition, it has not been known what kind of characteristics it will exhibit in its application.

Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms, an alkenyl group having 2 to 20 carbon atoms, or an alkoxy group having 1 to 20 carbon atoms. Represents a cycloalkyl group having 3 to 20 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.)

JP 2006-73636 A Japanese Patent Publication No. 2-24294

  The present invention has been made in view of such circumstances, and is an image display device and a flexible transparent organic electroluminescence element having a flexible polyimide film with high light transmittance, high heat resistance, high toughness and low water absorption. The purpose is to provide.

As a result of intensive studies to achieve the above object, the present inventor has obtained a transparency, a machine, and a polyimide film obtained from a combination of many alicyclic tetracarboxylic dianhydrides and diamine compounds. It has been found that the above-mentioned combination of NDA and BAPB is excellent as a monomer having a combination of mechanical strength, heat resistance, low water absorption, flexibility, film surface smoothness and the like.
That is, a film containing NDA-BAPB polyimide obtained by polycondensation and imidization of NDA represented by the above formula [5] and BAPB represented by the formula [6] has high light transmittance, high heat resistance, The present invention has been completed by discovering that it is flexible, has high toughness and low water absorption, and is useful as a substrate (optical film) for an image display device such as an organic EL display or a liquid crystal display.

That is, the present invention
1. An image display device using, as an optical film, a polyimide film containing at least 10 mol% of the repeating unit represented by the formula [1],
Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. Represents a cycloalkyl group having 3 to 7 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.)
2. 1. The image display device according to 1, wherein the optical film is a polyimide film containing at least 10 mol% of the repeating unit represented by the formula [2].
(In the formula, n represents the same meaning as described above.)
3. A flexible transparent organic electroluminescence device comprising a substrate made of a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [1],
Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. Represents a cycloalkyl group having 3 to 7 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.)
4). A substrate made of a polyimide film containing at least 10 mol% or more of the repeating unit represented by the formula [1], and an anode, a hole injection layer, a hole transport layer, and an organic material laminated on the substrate in the following order. 3 flexible transparent organic electroluminescence devices comprising a light emitting layer, an electron injection layer and a cathode;
(Wherein R ¹ , R ² , R ³ and n represent the same meaning as described above.)
5. 3 or 4 flexible transparent organic electroluminescent elements, wherein the substrate is made of a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [2]
(In the formula, n represents the same meaning as described above.)
I will provide a.

  According to the present invention, it is possible to provide an image display device and an organic electroluminescence element having a flexible polyimide film with high light transmittance, high heat resistance, high toughness and low water absorption.

Hereinafter, the present invention will be described in more detail.
In the above formula [1], examples of the halogen atom include a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom.
The alkyl group having 1 to 10 carbon atoms may be linear or branched, and specific examples thereof include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, s-butyl, t -Butyl, n-pentyl, i-amyl, t-amyl, neo-pentyl, n-hexyl, heptyl, octyl, nonyl, decyl group and the like can be mentioned.

Examples of the alkenyl group having 2 to 5 carbon atoms include vinyl, propenyl, butenyl and pentenyl groups.
Examples of the alkoxyl group having 1 to 5 carbon atoms include methoxy, ethoxy, n-propoxy, i-propoxy, n-butoxy, s-butoxy, t-butoxy, and n-pentoxy group.
Examples of the cycloalkyl group having 3 to 7 carbon atoms include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and cycloheptyl groups.
In the above, n represents normal, i represents iso, s represents secondary, and t represents tertiary.

In the present invention, the number average molecular weight of the polyimide is preferably at least 5000, more preferably 6000 to 100,000, considering the flexibility of the film.
For this reason, n in the above formulas [1] and [2] is preferably an integer having a polyimide number average molecular weight of 5000 or more. Specifically, 8 to 180 is preferable, and 10 to 100 is particularly preferable.

  The polyimide film used in the present invention may contain 10 mol% or more of the repeating structure represented by the above formula. In particular, in order to obtain a polyimide film having high heat resistance and transparency and excellent flexibility. Preferably contains 50 mol% or more of the above structure, more preferably 70 mol% or more, and most preferably 90 mol% or more.

  The polyimide which has a repeating unit represented by the said Formula [1] and [2] can be obtained by imidating the polyamic acid which has a repeating unit represented by following formula [3] and [4]. These polyamic acids represented by the formulas [3] and [4] can be synthesized by polycondensation of NDA represented by the formula [5] and BAPB represented by the formula [6] as described above.

(In the formula, R ^{1 to} R ³ and n represent the same meaning as described above.)

  In the present invention, BAPB is 1,3-bis (4-aminophenoxy) benzene (hereinafter abbreviated as DA4P), 1,4-bis (4-aminophenoxy) benzene, 1,3-bis (4- Amino-3-methylphenoxy) benzene, 1,3-bis (4-aminophenoxy) -5-methylbenzene, 3-bis (4-aminophenoxy) -5-decylbenzene, 1,3-bis (4-amino) Phenoxy) -5-eicosylbenzene, 3-bis (4-amino-3-dodecylphenoxy) -5-benzene, 1,3-bis (4-aminophenoxy) -5-cyanobenzene, 1,3-bis ( 4-aminophenoxy) -5-chlorobenzene, 1,3-bis (4-aminophenoxy) -5-decylbenzene, 1,3-bis (4-aminophenoxy) -5-me Xibenzene, 1,3-bis (4-aminophenoxy) -5-vinylbenzene, 1,3-bis (4-aminophenoxy) -5-allylbenzene, 1,3-bis (4-aminophenoxy) -5 Carboxybenzene, 1,3-bis (4-aminophenoxy) -5-cyclopropylbenzene, 3-bis (4-aminophenoxy) -5-cyclohexylbenzene, 1,3-bis (4-aminophenoxy) benzene, 1 , 4-bis (3-aminophenoxy) benzene, 1,3-bis (3-amino-4-methylphenoxy) benzene, 3-bis (3-aminophenoxy) -5-methylbenzene, 1,3-bis ( 3-aminophenoxy) -5-decylbenzene, 1,3-bis (3-aminophenoxy) -5-eicosylbenzene, 3-bis (3-amino 4-dodecylphenoxy) -5-benzene, 1,3-bis (3-aminophenoxy) -5-cyanobenzene, 1,3-bis (3-aminophenoxy) -5-chlorobenzene, 3-bis (3-amino Phenoxy) -5-decylbenzene, 1,3-bis (3-aminophenoxy) -5-methoxybenzene, 1,3-bis (3-aminophenoxy) -5-vinylbenzene, 1,3-bis (3- Minophenoxy) -5-allylbenzene, 1,3-bis (3-aminophenoxy) -5-carboxybenzene, 1,3-bis (3-aminophenoxy) -5-cyclopropylbenzene, 3-bis (3- Aminophenoxy) -5-cyclohexylbenzene and the like. Among these, DA4P is preferable from the viewpoint of physical properties of the obtained film.

  The polyimide film used in the present invention contains 10 mol% or more of the repeating unit of the above-mentioned formula [1] or [2] as long as it does not affect the physical properties of the obtained polyimide film. You may use simultaneously the tetracarboxylic-acid compound used for the synthesis | combination of a normal polyimide, and its derivative (s).

Specific examples thereof include 1,2,3,4-cyclobutanetetracarboxylic acid, 2,3,4,5-tetrahydrofurantetracarboxylic acid, 1,2,4,5-cyclohexane acid, 3,4-dicarboxy- 1-cyclohexyl succinic acid, 3,4-dicarboxy-1,2,3,4-tetrahydro-1-naphthalene succinic acid, bicyclo [3.3.0] octane-2,4,6,8-tetracarboxylic acid And alicyclic tetracarboxylic acids such as these, dianhydrides thereof, and dicarboxylic acid diacid halides thereof.
Also, pyromellitic acid, 2,3,6,7-naphthalenetetracarboxylic acid, 1,2,5,6-naphthalenetetracarboxylic acid, 1,4,5,8-naphthalenetetracarboxylic acid, 2,3,6 , 7-anthracenetetracarboxylic acid, 1,2,5,6-anthracenetetracarboxylic acid, 3,3 ′, 4,4′-biphenyltetracarboxylic acid, 2,3,3 ′, 4-biphenyltetracarboxylic acid, Bis (3,4-dicarboxyphenyl) ether, 3,3 ′, 4,4′-benzophenonetetracarboxylic acid, bis (3,4-dicarboxyphenyl) methane, 2,2-bis (3,4-di Carboxyphenyl) propane, 1,1,1,3,3,3-hexafluoro-2,2-bis (3,4-dicarboxyphenyl) propane, bis (3,4-dicarboxyphenyl) dimethyl Aromatic tetracarboxylic acids such as silane, bis (3,4-dicarboxyphenyl) diphenylsilane, 2,3,4,5-pyridinetetracarboxylic acid, 2,6-bis (3,4-dicarboxyphenyl) pyridine And acid dianhydrides thereof, and dicarboxylic acid diacid halides thereof. In addition, these tetracarboxylic acid compounds may be used individually by 1 type, or may be used in mixture of 2 or more types.

On the other hand, as long as the diamine contains 10 mol% or more of the repeating unit of the above formula [1] or [2] and does not affect the physical properties of the resulting polyimide film, other diamine compounds other than the above BAPB May be used.
Specific examples thereof include p-phenylenediamine, m-phenylenediamine, 2,5-diaminotoluene, 2,6-diaminotoluene, 4,4′-diaminobiphenyl, 3,3′-dimethyl-4,4′-. Diaminobiphenyl, 3,3′-dimethoxy-4,4′-diaminobiphenyl, diaminodiphenylmethane, diaminodiphenyl ether, 2,2′-diaminodiphenylpropane, bis (3,5-diethyl-4-aminophenyl) methane, diaminodiphenyl Sulfone, diaminobenzophenone, diaminonaphthalene, 1,4-bis (4-aminophenoxy) benzene, 1,4-bis (4-aminophenyl) benzene, 9,10-bis (4-aminophenyl) anthracene, 1,3 -Bis (4-aminophenoxy) benzene, 4,4'-bis (4- Minophenoxy) diphenylsulfone, 2,2-bis [4- (4-aminophenoxy) phenyl] propane, aromatic diamines such as 2,2′-trifluoromethyl-4,4′-diaminobiphenyl, bis (4- Alicyclic diamine compounds such as aminocyclohexyl) methane, bis (4-amino-3-methylcyclohexyl) methane, 4,4′-methylenebis (2-methylcyclohexylamine) and aliphatics such as tetramethylenediamine and hexamethylenediamine A diamine compound etc. are mentioned, These diamine compounds can be used individually by 1 type or in mixture of 2 or more types.

The ratio of the number of moles of all tetracarboxylic dianhydride compounds to the number of moles of all diamine compounds when synthesizing the polyamic acid is preferably carboxylic acid compound / diamine compound = 0.8 to 1.2. Similar to the normal polycondensation reaction, the closer the molar ratio is to 1, the higher the degree of polymerization of the polymer produced. If the degree of polymerization is too small, the strength of the polyimide coating film becomes insufficient, and if the degree of polymerization is too large, workability at the time of forming the polyimide coating film may be deteriorated.
Therefore, the degree of polymerization of the product in this reaction is 0.05 to 5.0 dl / g (in N-methyl-2-pyrrolidone at 30 ° C., concentration 0.5 g / dl) in terms of reduced viscosity of the polyamic acid solution. Is preferred.

Examples of the solvent used for polyamic acid synthesis include m-cresol, N-methyl-2-pyrrolidone (NMP), N, N-dimethylformamide (DMF), N, N-dimethylacetamide (DMAc), and N-methyl. Examples include captolactam, dimethyl sulfoxide, tetramethyl urea, pyridine, dimethyl sulfone, hexamethyl phosphoramide, and γ-butyrolactone. These may be used alone or in combination. Furthermore, even if it is a solvent which does not melt | dissolve a polyamic acid, you may use it in addition to the said solvent within the range in which a uniform solution is obtained.
The temperature of the polycondensation reaction can be selected from -20 to 150 ° C, preferably -5 to 100 ° C.

The polyimide used in the present invention can be obtained by subjecting the polyamic acid synthesized as described above to dehydration ring closure (thermal imidization) by heating. At this time, it is also possible to convert polyamic acid to imide in a solvent and use it as a solvent-soluble polyimide.
Moreover, the method of chemically ring-closing using a well-known dehydration ring-closing catalyst is also employable.
The method by heating can be performed at an arbitrary temperature of 100 to 300 ° C, preferably 120 to 250 ° C.
The chemical ring closure method can be performed, for example, in the presence of pyridine, triethylamine, and the like, and acetic anhydride, and the temperature at this time can be selected from -20 to 200 ° C. .

The polyimide solution thus obtained can be used as it is, or precipitated by adding a poor solvent such as methanol or ethanol, and the resulting polyimide is used as a powder or the polyimide powder is appropriately used. It can be used by re-dissolving in a solvent.
The solvent for re-dissolution is not particularly limited as long as it can dissolve the obtained polyimide. For example, m-cresol, 2-pyrrolidone, NMP, N-ethyl-2-pyrrolidone, N-vinyl-2 -Pyrrolidone, DMAc, DMF, γ-butyrolactone and the like.

  Moreover, even if it is a solvent which does not melt | dissolve a polyimide independently, if it is a range which does not impair solubility, it can be used in addition to the said solvent. Specific examples thereof include ethyl cellosolve, butyl cellosolve, ethyl carbitol, butyl carbitol, ethyl carbitol acetate, ethylene glycol, 1-methoxy-2-propanol, 1-ethoxy-2-propanol, and 1-butoxy-2-propanol. 1-phenoxy-2-propanol, propylene glycol monoacetate, propylene glycol diacetate, propylene glycol-1-monomethyl ether-2-acetate, propylene glycol-1-monoethyl ether-2-acetate, dipropylene glycol, 2- (2-Ethoxypropoxy) propanol, lactate methyl ester, lactate ethyl ester, lactate n-propyl ester, lactate n-butyl ester, lactate isoamyl ester, etc.

The polyimide film used in the present invention is obtained by applying a polyamic acid solution obtained by polymerization and an organic solvent solution of polyimide obtained by reprecipitation after chemically imidizing the solution onto a substrate such as a glass plate, Can be produced by evaporating.
In that case, after pre-baking at 50 to 100 ° C. for 1 to 5 hours under reduced pressure of 1 to 1000 Pa, more than 100 ° C. to 160 ° C. for 1 to 5 hours, then more than 160 ° C. to 200 ° C. for 1 to 5 hours, Furthermore, by adopting a multi-step temperature raising method in which baking is performed at a temperature exceeding 200 ° C. to 300 ° C. for 1 to 5 hours, a polyimide film with little coloration and high surface smoothness can be produced.

The polyimide film thus prepared has a film thickness of 50 to 500 μm, light transmittance of 80% or more at 400 nm, 10% weight loss temperature of 300 ° C. or more, water absorption of 1% or less, Young's modulus of 2.0 GPa or more, maximum It has high transparency with an elongation of 5% or more, high mechanical strength, high heat resistance, low water absorption, and flexibility.
This polyimide film can be suitably used as a substrate for an image display device such as an organic EL display substrate and a liquid crystal display substrate. Since the image display apparatus and the organic EL element of the present invention are characterized by the use of the polyimide film, other constituent members may be appropriately selected from conventionally known ones.
As typical examples, application examples to an organic EL display device will be described below.

The flexible transparent organic electroluminescent element of the present invention comprises a substrate made of the above-described polyimide film. Specific examples thereof include a transparent anode, a hole injection layer, a hole transport layer, and an organic substance on the polyimide film substrate. A light emitting layer, an electron injection layer, and a transparent cathode are laminated in this order.
As the anode and the cathode, an amorphous transparent electrode in which a metal oxide is generally formed by sputtering or ion plating is used.
The anode and the cathode are formed in a matrix, and a pixel is caused to emit light by applying a voltage between the anode and the cathode and passing a current through the organic EL layer. The generated light is extracted outside from the anode electrode side.

EXAMPLES Hereinafter, although a synthesis example and an Example are given and this invention is demonstrated more concretely, this invention is not limited to the following Example. The measuring device for each physical property in the examples is as follows.
[1] Molecular weight apparatus: room temperature GPC measurement apparatus (SSC-7200, manufactured by Senshu Kagaku Co., Ltd.)
Eluent: DMF
[2] TG / DTA (differential calorific value simultaneous measurement device)
Device: Thermoplus TG8120 (manufactured by Rigaku Corporation)
[3] FT-IR
Device: NICOLET 5700 (Thermo ELECTRON CORPORATION)
[4] Film thickness measuring device: Micrometer (manufactured by Suntop Co., Ltd.)
[5] UV-Vis spectrum apparatus: UV-VIS-NIR SCANNING SPECTROTOPOMETER (self-recording spectrophotometer) (manufactured by Shimadzu Corporation)
[6] Testronics Co., Ltd. (1) Maximum stress (2) Yield strength (3) Young's modulus (4) Breaking load (5) Maximum elongation Film dimension W × t (mm): 10.2 × 0.144
Cross-sectional area (mm ² ): 1.4688

[Synthesis Example 1] Synthesis of NDA-DA4P polyamic acid and polyimide

In a 50 mL four-neck reaction flask equipped with a stirrer placed in a 25 ° C. water bath, 1.96 g (7 mmol) of DA4P and 15.0 g of NMP were charged and dissolved. Subsequently, 1.75 g (7 mmol) of NDA was added while the solution was being stirred. Furthermore, it stirred at 25 degreeC for 27 hours, the polymerization reaction was performed, and the polyamic acid solution with a solid content of 20 mass% was obtained.
DMF was added to this solution to adjust the solid content to 5% by mass, and the molecular weight was measured by the GPC method. As a result, the number average molecular weight (Mn) was 12,449 and the weight average molecular weight (Mw) was 13,016. Mw / Mn was 1.05.

After casting this solution on a 75 mm × 100 mm glass plate, it is put in a vacuum dryer and subjected to stepwise baking at 80 ° C./2 hours, 120 ° C./2 hours, 180 ° C./2 hours and 240 ° C./2 hours. went. Then, the glass substrate with a film was immersed in a 80 degreeC hot water bath for 5 hours, and the film was peeled off from the glass plate. The peeled film was again put into a vacuum dryer and dried under reduced pressure at 140 ° C./2 hours.
170.48 cm ⁻¹ (5-membered cyclic imide) was confirmed from the infrared absorption spectrum of the obtained film, and the imidization rate was calculated to be 96%. Various physical property values were as follows.

Film thickness: 144μm
Light transmittance: 81%
Maximum stress (kg / mm ² ): 7.17
Yield strength (kg / mm ² ): 5.00
Young's modulus (GPa): 2.14
Breaking load (kgf): 9.977
Maximum elongation (%): 5.43
Glass transition point: None 10% Weight loss temperature (° C): 393
Water absorption rate (%): 0.4

  From the above physical property values, the NDA-DA4P polyimide film obtained in Synthesis Example 1 is a flexible film having high transparency, high mechanical strength, high heat resistance, low water absorption, and flexibility. confirmed.

[Example 1] Preparation and evaluation of organic EL device (1) Synthesis of NDA-DA4P polyamic acid and polyimide In a 50 mL four-necked reaction flask equipped with a stirrer placed in a 25 ° C water bath, 1.67 g (6 mmol) DA4P and NMP18 0.0 g was charged and dissolved. Subsequently, the solution was added while dissolving 1.50 g (6 mmol) of NDA while stirring. Furthermore, it stirred at 27 degreeC for 32 hours, the polymerization reaction was performed, and the polyamic acid solution with a solid content of 15 mass% was obtained.
The solution was cast on a 12 cm × 8 cm glass plate, and then placed in a vacuum dryer at 80 ° C./2 hours, 120 ° C./2 hours, 180 ° C./2 hours, and 240 ° C./2 hours under a reduced pressure of 10 Pa. The stepwise firing was performed. Furthermore, the glass substrate with a film was immersed in an 80 ° C. hot water bath for 5 hours, and the film was peeled off from the glass plate. The peeled film was again put into a vacuum dryer and dried under reduced pressure at 200 ° C./2 hours. The obtained film had a thickness of 83 μm and a light transmittance of 84%.

(2) Examination results of NDA-DA4P polyimide organic EL element substrate Using the NDA-DA4P polyimide film prepared in (1) above as a substrate, a polymer organic EL element was prepared under the following conditions, and its performance evaluation was performed. Went. The performance was measured using an organic EL luminous efficiency measuring device (EL1003, manufactured by Precise Gauge Co., Ltd.).

(A) Cleaning process: UV ozone cleaning (b) Anode film forming process Equipment: RF conical target sputtering (manufactured by ALS Technology)
Substrate temperature: Room temperature (25 ° C)
Ultimate vacuum: ≦ 5.0 × 10 ⁻⁴ Pa
Deposition vacuum: ≦ 1.0 × 10 ⁻¹ Pa
Output: 200W
Pre-sputtering time: 5 min.
Sputtering time: 120 min.
Gas flow rate: Ar (10.0 sccm)
(C) Organic vapor deposition film process Vacuum degree: ≦ 7.0 × 10 ⁻⁴ Pa
Deposition rate: ≤0.2nm / sec
(D) Cathode film forming conditions Vacuum degree: ≦ 7.0 × 10 ⁻⁴ Pa
Deposition rate: ≦ 0.7nm / sec
(E) Organic EL element structure Film substrate / ITO (350 nm) / PEDOT-PSS (70 nm) / NPB (30 nm) / Alq ₃ (40 nm) / Al—Li (40 nm)
/ Al (100 nm)
PEDOT-PSS (Aldrich) was formed by spin coating.
Film formation conditions: 2750 rpm, 30 sec
Drying conditions after film formation: in air, baking temperature: 200 ° C., baking time: 10 minutes

[Evaluation results]
(1) Appearance of the device The device produced in Example 1 in the non-light-emitting state is shown in the left diagram of FIG. 1, and the light-emitting mode in the luminance measurement is shown in the right diagram of FIG. The luminance was about 200 cd / m ² .
(2) Luminance vs. Voltage Characteristics The relationship between emission luminance and voltage is shown in FIG. The luminance was 8 V: 10 ² cd / m ^{2 to 20} V: 10 ³ cd / m ² .
(3) Current density-voltage characteristics The relationship between current density and voltage is shown in FIG. 1V: 1mA / cm ² ~20V: shows a current range of 30 mA / cm ^2.
(4) Luminous efficiency-current density characteristics The relationship between luminous efficiency and current density is shown in FIG. The light emission efficiency was 5 mA / cm ² : 3.5 cd / A.
As described above, the element using the present invention the flexible polyimide film substrate, the maximum emission luminance: about 1000 cd / m ^2, the maximum luminous efficiency: reached about 3.5 cd / m ^2.

It is a figure which shows the mode at the time of the light emission at the time of the non-light emission of the organic EL element produced in Example 1, and a brightness | luminance measurement. FIG. 4 is a diagram showing light emission luminance-voltage characteristics of the organic EL element produced in Example 1. FIG. 4 is a diagram showing current density-voltage characteristics of an organic EL element produced in Example 1. FIG. 3 is a graph showing the light emission efficiency-current density characteristics of the organic EL device produced in Example 1.

Claims (5)

An image display device using, as an optical film, a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [1].
Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. Represents a cycloalkyl group having 3 to 7 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.) The image display device according to claim 1, wherein the optical film is a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [2].
(In the formula, n represents the same meaning as described above.) A flexible transparent organic electroluminescence device comprising a substrate made of a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [1].
Wherein R ¹ , R ² and R ³ are each independently a hydrogen atom, a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkenyl group having 2 to 5 carbon atoms, or an alkoxyl group having 1 to 5 carbon atoms. Represents a cycloalkyl group having 3 to 7 carbon atoms, a nitrile group, or a carboxyl group, and n represents an integer.) A substrate made of a polyimide film containing at least 10 mol% or more of the repeating unit represented by the formula [1], and an anode, a hole injection layer, a hole transport layer, and an organic material laminated on the substrate in the following order. The flexible transparent organic electroluminescent element according to claim 3, comprising a light emitting layer, an electron injection layer, and a cathode.
(Wherein R ¹ , R ² , R ³ and n represent the same meaning as described above.) The flexible transparent organic electroluminescent element according to claim 3 or 4, wherein the substrate is made of a polyimide film containing at least 10 mol% of a repeating unit represented by the formula [2].
(In the formula, n represents the same meaning as described above.)