JPH05194943A - Organic electroluminescent device - Google Patents

Abstract

(57) [Abstract] [Purpose] To develop an organic electroluminescence device having a high Tg and melting point and a long life. [Structure] General formula (I) (In the formulae, R ¹ , R ² , R ⁷ , R ⁸ and X are as described in the specification.) Or, the compound represented by the general formula (II): (In the formula, R ¹ , R ² , R ⁷ , R ⁸ and X are as described in the specification.) An organic electroluminescence device using a compound as a hole injection material.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device, and more particularly to a long-life organic electroluminescence device using a hole injection material having a high glass transition temperature (Tg) and a high melting point.

[0002]

PRIOR ART AND PROBLEMS TO BE SOLVED BY THE INVENTION
Ctroluminescence elements (EL elements) are self-luminous.
Therefore, it has high visibility, and it is a solid-state element, and it is shock resistant.
Since it has excellent characteristics,
Various devices using organic and organic compounds have been proposed, and
Practical application is being attempted. Of these elements, organic E
L element can significantly reduce the applied voltage
Therefore, the development of various materials and devices is in progress. The organic
There are various EL element configurations, but ITO
/ Hole injection layer / light-emitting layer / hole injection in cathode device configuration
The use of aromatic tertiary amines as the material for the layer
It has been disclosed (JP-A-63-295695).
Particularly preferable examples of the aromatic tertiary amine include Q
¹-G-Q²It is represented by the structural formula. Where Q¹When
Q²Are each independently an aromatic tertiary amine, and G is
Of arylene, cycloalkylene or alkylene groups
Such linking groups or carbon-carbon bonding groups. This element
Depending on the configuration, an applied voltage of 20 V or more will cause several hundred cd / m ²High
Brightness made possible. However, the hole injection used here
The material is, for example, N, N, N ', N'-tetraphenyl
Ru-4,4'-diaminobiphenyl; 1,1-bis (4
-Di-p-tolylaminophenyl) -cyclohexane etc.
Recrystallization occurs in the hole injection layer using
Therefore, the formation of pinholes in the element and deterioration of energization over time
However, there was a problem in obtaining a device having a long life.
This is an aromatic tertiary amine used as a hole injection material.
Has a low melting point of less than 200 ° C, and in the amorphous state
The glass transition temperature (Tg) is 90 ° C or lower,
As a result, heat resistance is low, and thermal deterioration progresses even at room temperature.
Because it was. Also, inject the styrylamine derivative with holes.
A technique used as an entrance layer is disclosed (JP-A-3-5).
4289), the Tg of the hole injection layer is also 9
Since the temperature was 0 ° C. or lower, the above problems were not solved. It
In addition, a distyrylbenzene derivative was used as the device material.
Japanese Patent Laid-Open No. 3-163187
However, this also shows that the Tg of the hole injection layer is below 90 ° C.
The problem was not solved.

[0003]

Therefore, the present inventors have
As a result of intensive studies to solve the above problems, it was found that a long-life organic EL device can be obtained by using a distyrylbenzene derivative having a high Tg and a high melting point as a hole injection material.

The present invention has been completed based on such findings. That is, the present invention has the general formula (I)

[0005]

[Chemical 4]

(In the formula, R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkyl group-substituted aryl group having 6 to 20 carbon atoms, and 6 to 6 carbon atoms. 20 shows an aryloxy group-substituted aryl group having 20 or an alkoxy group-substituted aryl group having 6 to 20 carbon atoms.
R ⁷ and R ⁸ are each independently hydrogen and having 1 to 10 carbon atoms.
Alkyl group, C6-20 aryl group, C1
It shows an alkoxy group having 10 to 10 or an aryloxy group having 6 to 20 carbon atoms. Also, X is the formula

[0007]

[Chemical 5]

(Here, R ^{3 to} R ⁶ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms or 1 to 10 carbon atoms.
Is an alkoxy group. ) Is a divalent group. ) Or general formula (II)

[0009]

[Chemical 6]

(Wherein R ¹ , R ² , R ⁷ , R ⁸ and X
Is the same as above. The present invention provides an organic electroluminescence device characterized by using the compound represented by the formula (1) as a hole injection material.

In the present invention, the compound used as the hole injecting material is a compound represented by the above general formula (I) or (II). Here, R ¹ and R ² are each independently an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group,
n-propyl group, i-propyl group, n-butyl group, i-
Butyl group, sec-butyl group, tert-butyl group, isopentyl group, t-pentyl group, neopentyl group, isohexyl group, heptyl group, octyl group, nonyl group, decyl group, etc.), aryl group having 6 to 20 carbon atoms ( Phenyl group, naphthyl group, biphenyl group, anthranyl group, phenanthranyl group, etc.), alkyl group-substituted aryl group having 6 to 20 carbon atoms (tolyl group, dimethylphenyl group, ethylphenyl group, methylnaphthyl group, dimethylnaphthyl group, etc.), C6-C20 alkoxy group-substituted aryl group (methoxyphenyl group, ethoxyphenyl group, methoxynaphthyl group,
Ethoxynaphthyl group, etc.), aryloxy group-substituted aryl group having 6 to 20 carbon atoms (phenoxyphenyl group, naphthooxyphenyl group, phenoxynaphthyl group, phenoxyanthranyl group, etc.), and R ⁷ and R ⁸ are independently hydrogen. , An alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert-butyl group,
Isopentyl group, tert-pentyl group, neopentyl group,
Isohexyl group, heptyl group, octyl group, nonyl group,
Decyl group), aryl group having 6 to 20 carbon atoms (phenyl group, naphthyl group, biphenyl group, anthranyl group, phenanthranyl group, etc.), alkoxy group having 1 to 10 carbon atoms (methoxy group, ethoxy group, n-propoxy group) , I-propoxy group, n-butoxy group, i-butoxy group, sec-
Butoxy group, tert-butoxy group, t-pentoxy group, etc.) or aryloxy group having 6 to 10 carbon atoms (phenoxy group, naphthyloxy group, etc.). Furthermore, X is an expression

[0012]

[Chemical 7]

A divalent group represented by: Where R ³
To R ⁶ are each independently hydrogen, an alkyl group having 1 to 10 carbon atoms (methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, sec-butyl group, tert. -Butyl group, isopentyl group, t-pentyl group,
Neopentyl group, isohexyl group, heptyl group, octyl group, nonyl group, decyl group, etc.), or C1-10
Alkoxy group (methoxy group, ethoxy group, n-propoxy group, i-propoxy group, n-butoxy group, i-butoxy group, sec-butoxy group, tert-butoxy group, isopentyloxy group, t-pentyloxy group , Neopentyloxy group, isohexyloxy group, heptyloxy group, octyloxy group, nonyloxy group, decyloxy group, etc.)
Indicates.

The compound represented by the general formula (I) or the general formula (II) used in the present invention has two methylidyne (-HC = CH-) units in one molecule, and the geometry of the methylidyne unit is Depending on the isomerism, there are four possible combinations: cis-cis, trans-cis, cis-trans and trans-trans. The hole injection material of the present invention may be any of them, or may be a mixture of geometric isomers. Particularly preferably, all are trans.

In the compound represented by the general formula (I) or the general formula (II) in the EL device of the present invention, the divalent group as described above is used as X, and the structure in which Tg exceeds 90 ° C. Is preferably selected. For example, the bonding position is 1,4 bond position for phenylene group, 4,4 'bond position for biphenylene or 4,4''' bond position for terphenylene group, and as a divalent group that cuts the conjugated system, ,

[0016]

[Chemical 8]

And the like. Such a general formula (I)
Or as a specific example of the hole injection material represented by (II),

[0018]

[Chemical 9]

[0019]

[Chemical 10]

[0020]

[Chemical 11]

[0021]

[Chemical formula 12]

[0022]

[Chemical 13]

[0023]

[Chemical 14]

[0024]

[Chemical 15]

[0025]

[Chemical 16]

[0026]

[Chemical 17]

[0027]

[Chemical 18]

[0028]

[Chemical 19]

And the like. The compounds H1 to H30 represented by the general formula (I) or (II) are mixed solutions of phosphonate ester and aldehyde (solvent: ethanol, benzene, tetrahydrofuran (THF), N, N-dimethylformamide (DMF), Dimethyl sulfoxide (DMSO) etc. is used as a base (NaH, NaNH ₂ , ROM)
(R: alkyl group, M: Li, Na, K, etc.) to give a high yield of olefin.
It can be easily synthesized by the r reaction (Horner L ,;
HoffmannH .; Wippel HG; Chem. Be r., (1959) 92, 24
99).

The hole injection material used in the present invention comprises a compound represented by the above general formula (I) or (II),
This can be used not only as a material for the hole injection layer but also as a material for the light emitting layer. The hole injection layer in the organic EL device of the present invention is made of the above hole injection material and has a function of transmitting the holes injected from the anode to the light emitting layer.
By sandwiching this layer between the anode of the EL element and the light emitting layer, more holes are injected into the light emitting layer at a low voltage, and the brightness of the element is improved. The hole injecting material of the hole injecting layer is disposed between two electrodes provided with an electric field to facilitate the injection of holes from the anode, and at the same time, appropriately transfer the holes to the light emitting layer. It is a compound that can By sandwiching the hole injection layer between the anode and the light emitting layer, many holes are injected into the light emitting layer with a lower electric field. Further, the electrons injected from the cathode or the electron injection layer into the light emitting layer are accumulated near the interface in the light emitting layer due to the electron barrier existing at the interface between the light emitting layer and the hole injection layer, and the luminous efficiency is improved. Preferred hole injecting materials herein are at least 10 ^-6 c when the layer is placed between electrodes that are provided with an electric field of 10 ⁴ -10 ⁶ volts / cm.
It has a hole mobility of m ² / volt · second.

The laminated structure in the organic EL device of the present invention is as follows: (1) anode / hole injection layer / light emitting layer / electron injection layer / cathode laminated in this order, (2) anode / hole injection layer / light emitting layer / cathode. It is preferable that the layers are laminated in this order, (3) anode / light emitting layer / electron injection layer / cathode are laminated in this order, or (4) anode / light emitting layer / cathode are laminated in this order. It should be noted that these organic EL elements are preferably formed on a supporting substrate. The substrate that can be used in the organic EL device of the present invention is preferably a substrate having transparency, and generally glass, transparent plastic,
Quartz or the like is used. As the positive electrode in this EL element, a material having an electrode substance of a metal, an alloy, an electrically conductive compound having a large work function (4 eV or more) and a mixture thereof is preferably used. Specific examples of such an electrode material include metals such as Au, CuI, ITO, SnO ₂ ,
A conductive transparent material such as ZnO may be used. The positive electrode is
These electrode materials can be produced by forming a thin film by a method such as vapor deposition or sputtering. When taking out light emission from this electrode, the transmittance is set to 1
It is desirable to make it larger than 0%, and the sheet resistance as an electrode is preferably several hundred Ω / □ or less. Further, although the film thickness depends on the material, it is usually selected in the range of 10 nm to 1 μm, preferably 10 to 200 nm. On the other hand, as the cathode, one having a low work function (4 eV or less) metal, alloy, electrically conductive compound or a mixture thereof as an electrode substance is used. Specific examples of such electrode materials include sodium, sodium-potassium alloys, magnesium, lithium, magnesium / copper mixtures, Al / Al.
Examples include ₂ O ₃ and indium. The cathode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. The sheet resistance of the electrode is preferably several hundred Ω / □ or less, and the film thickness is usually 10 to 500 nm, preferably 5
It is selected in the range of 0 to 200 nm. In order to transmit the emitted light, it is convenient that either the anode or the cathode of the organic EL element is transparent or semi-transparent so that the luminous efficiency is improved.

Further, in the present invention, the light emitting material of the light emitting layer is not particularly limited, and any one of conventionally known compounds can be selected and used. In addition,
The compound represented by the general formula (I) or (II) can be mixed in a part of the light emitting layer.

Examples of the light-emitting material include polycyclic condensed aromatic compounds, benzoxazole-based, benzothiazole-based, benzimidazole-based optical brighteners, metal chelated oxanoide compounds, distyrylbenzene-based compounds, and the like. It is possible to use a compound having a good Here, as the polycyclic fused aromatic compound, for example, a condensed ring light-emitting substance containing anthracene, naphthalene, phenanthrene, pyrene, chrysene, and perylene skeleton, or another condensed ring light-emitting substance containing about eight condensed rings is used. Can be mentioned.

As the above-mentioned fluorescent whitening agents of the benzoxazole type, benzothiazole type, benzimidazole type and the like, for example, those described in JP-A-59-194393 can be used, and representative examples thereof can be used. ,
2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) -1,3,4-thiadiazole; 4,
4'-bis (5,7-t-pentyl-2-benzoxazolyl) stilbene; 4,4'-bis (5,7-di-
(2-Methyl-2-butyl) -2-benzoxazolyl) stilbene; 2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) thiophene; 2,5-
Bis (5- (α, α, -dimethylbenzyl) -2-benzoxazolyl) thiophene; 2,5-bis (5,7-
Di- (2-methyl-2-butyl) -2-benzoxazolyl) -3,4-diphenylthiophene; 2,5-bis (5-methyl-2-benzoxazolyl) thiophene;
4,4'-bis (2-benzoxazolyl) biphenyl; 5-methyl-2- (2- (4- (5-methyl-2-
Benzoxazolyl) phenyl) vinyl) benzoxazole; benzoxazoles such as 2- (2- (4-chlorophenyl) vinyl) naphtho (1,2-d) oxazole, 2,2 '-(p-phenylenedivinylene) ) -Bisbenzothiazole and other benzothiazoles, 2- (2-
(4- (2-benzimidazolyl) phenyl) vinyl)
Benzimidazole; Fluorescent brighteners such as benzimidazole series such as 2- (2- (4-carboxyphenyl) vinyl) benzimidazole.

As the metal chelated oxanoide compound, for example, those described in JP-A-63-295695 can be used. Typical examples are tris (8-quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo (f) -8-quinolinol) zinc, bis (2-methyl-).
8-quinolinolato) aluminum oxide, tris (8-quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, 8-quinolinol lithium, tris (5-chloro-8-quinolinol) gallium, bis (5-chloro-) 8-quinolinol) calcium, poly (zinc (II) -bis (8-hydroxy-5-
Examples thereof include 8-hydroxyquinoline-based metal chain bodies such as quinolinonyl) methane) and dilithium epindridione.

Besides, distyrylbenzene derivatives described in European Patent No. 0373582, 038876.
Dimethylidene derivative described in Japanese Patent No.
Coumarin derivative of Japanese Patent No. 91694, JP-A-2-252
Distyrylpyrazine derivatives disclosed in Japanese Patent No. 793, JP-A-2-
Perylene derivative of 196885, JP-A 2-25
Naphthalene derivatives disclosed in Japanese Patent No. 5789, JP-A-2-289
The phthaloperinone derivative of JP-A No. 676 and JP-A No. 2-88689, the styrylamine derivative of JP-A No. 2-250292, and the cyclopentadiene derivative of JP-A No. 2-289675 are appropriately selected depending on the desired emission color and performance. be able to. The light emitting layer made of the above organic compound may have a laminated structure of two or more layers as desired, and may be formed by adding a fluorescent substance as disclosed in US Pat. No. 4,769,292. Good. In this case, the above-mentioned organic compound is a thin film-like layer and is responsible for a part of the injection function and the light-emitting function of the function of the light emitting region, while the fluorescent substance is present in the layer of the organic compound in a trace amount (several mol% or less). It plays a part of a light emitting function of emitting light in response to recombination of electrons and holes. Further, the organic compound used in the light emitting region may be a compound having no thin film property, and examples of such a compound include 1,4
-Diphenyl-1,3-butadiene; 1,1,4,4-
Tetraphenyl-1,3-butadiene; tetraphenylcyclopentadiene and the like. However, these materials that do not have a thin film property have a shortcoming that the life of the device is short. On the other hand, in the organic EL device of the present invention, the electron injection layer may be omitted, but a device having an electron injection layer is more preferable, and the light emission performance is further improved. The electron injection layer is composed of a compound that transmits electrons. Preferred examples of the electron injection material forming the electron injection layer include:

[0037]

[Chemical 20]

Nitro-substituted fluorenone derivatives such as those described above, anthraquinodimethane derivatives described in JP-A-57-149259, 58-55450, 63-104061 and the like, Polymer Preprints, Japan Vol.
37, No. 3 (1988), p.681 etc.

[0039]

[Chemical 21]

Diphenylquinone derivatives such as thiopyran dioxide derivatives such as JJ APPl. Phys., 27, L
269 (1988) etc.

[0041]

[Chemical formula 22]

Thiopyran dioxide derivatives such as J.
J. Appl. Phys., 27, L 269 (1988) etc.

[0043]

[Chemical formula 23]

A compound represented by: JP-A-60-6965
No. 7, No. 61-143764, No. 61-148159.
Fluorenylidene methane derivatives described in JP-A Nos. 61-225151 and 61-23375.
Examples thereof include the anthraquinodimethane derivative and anthrone derivative described in JP-A-0.
In addition, the following general formulas (III) and (IV)

[0045]

[Chemical formula 24]

(In the formula, Ar³~ Ar^FiveAnd Ar⁷Haso
Each independently represents an aryl group, Ar ⁶Is an arylene group
Indicates. These aryl and arylene groups are substituted
It may or may not be substituted. )
Compounds can be mentioned. Where the aryl group and
Phenyl group, naphthyl group, biphenyl group,
Examples thereof include a tolanyl group, a perylenyl group, a pyrenyl group, and the like,
As the arylene group, a phenylene group, a naphthylene group,
Biphenylene group, Anthracenylene group, Perylene
Group, pyrenylene group and the like. Also, as a substituent
Is an alkyl group having 1 to 10 carbon atoms and an alkyl group having 1 to 10 carbon atoms.
Examples thereof include lucoxy group and cyano group. This general formula
The compounds represented by (III) and (IV) are thin film-forming compounds.
Those are preferable. This is represented by the general formulas (III) and (IV)
Specific examples of the compound

[0047]

[Chemical 25]

[0048]

[Chemical formula 26]

[0049]

[Chemical 27]

And the like. In order to prepare an organic EL device having the above-mentioned constitution (1) anode / hole injection layer / light emitting layer / electron injection layer / cathode using such a device material, for example, the following procedure is used. Good. That is, first, an electrode is formed on the substrate by vapor deposition or sputtering. At this time, the film thickness of the film-like electrode is generally 10 nm to 1 μm, and particularly preferably 200 nm or less in order to increase the transmittance of light emission. Next, a hole injection material is formed in a thin film on this electrode to form a hole injection layer. The thinning method at this time includes spin coating, casting, vapor deposition and the like, but the vacuum vapor deposition is particularly preferable because a uniform film is easily obtained and pinholes are not formed. When the vapor deposition method is adopted for thinning, the vapor deposition conditions are, for example, boat heating temperature 50 to 400 ° C., vacuum degree 10 ⁻⁵ to 10 ⁻³ Pa, vapor deposition rate 0.01 to 50 nm / sec, substrate temperature −50. ~ + 300 ℃
The film thickness may be selected to be 5 nm to 5 μm in the range. The above-mentioned conditions differ depending on the type of compound and the target crystal structure, association structure, etc. of the molecular deposited film,
Although it cannot be uniquely determined, it is preferable to keep the heating temperature of the boat at a temperature at which the compound does not decompose. After forming the hole injection layer, a light emitting material is laminated on the light emitting layer to form a thin film by, for example, a vacuum deposition method. The vapor deposition conditions at this time are the same as the conditions at the time of forming the said light emitting layer. Then, the electron injection layer is formed in the same manner. After that, a counter electrode is formed by a vapor deposition method or a sputtering method to have a film thickness of 50 to 200 nm, whereby a target organic EL element is prepared. Here, the order of hole injection layer / light emitting layer / electron injection layer is changed to electron injection layer / light emitting layer / hole injection layer, and the order of electrode / electron injection layer / light emitting layer / hole injection layer / electrode is changed. You may produce.

(2) Anode / hole injection layer / light emitting layer /
In order to prepare an EL device having a cathode structure, first, the electrode, the hole injecting and transporting layer, the light emitting layer, and the counter electrode are formed by the organic EL device of (1)
If formed in the same manner as the element, the intended organic EL element having the above-mentioned configuration (2) is produced.

Further, (3) to prepare an organic EL device having the structure of anode / light emitting layer / cathode, a hole injection layer and an electron injection are carried out when the organic EL device of the above structure (1) is prepared. The formation of layers may be omitted. Further, as a manufacturing method in the case of an element composed of an anode / a light emitting layer / a cathode, in which a hole injecting material, a light emitting material and an electron injecting material are mixed between a pair of electrodes and sandwiched between the electrodes to form a light emitting layer, , For example, a thin film made of an anode material is formed on a suitable substrate, and a solution of a hole injecting material, a light emitting material, an electron injecting material, a binder such as polyvinylcarbazole, or the like is applied, or this solution is applied. To form a thin film by a dip coating method from
There is one in which a thin film made of a substance for a cathode is formed thereon. Here, an element material which is a material of the light emitting layer may be further vacuum-deposited on the manufactured light emitting layer, and a thin film made of a substance for a cathode may be formed thereon.

Organic E of the present invention obtained as described above
When the voltage applied to the L element is AC (AC drive), light emission is observed only in the bias state in which a positive voltage is applied to the anode side. Further, when the applied voltage is DC (DC drive), light emission is always observed by applying a positive voltage to the anode side.

[0054]

EXAMPLES The present invention will be described in more detail with reference to synthesis examples, examples and comparative examples. Synthesis example 1

[0055]

[Chemical 28]

1.8 g of a phosphonate ester represented by is dissolved in 20 ml of DMSO under an argon atmosphere,
1.0 g of potassium-t-butoxide (tBuOK) was added. Then, 2.0 g of N-ethylcarbazole-3-carboxaldehyde was added, and the mixture was stirred at room temperature for 5 hours. As a result of adding 100 ml of methanol to the obtained reaction product, a yellow powder was deposited. A benzene solution containing I ₂ was added to this powder and recrystallized to obtain 0.8 g of a yellow powder. The melting point of the obtained product was 300 ° C. or higher.

Further, proton nuclear magnetic resonance ( ¹ H-NMR
Spectrum), infrared absorption (IR) spectrum, and measurement results of elemental analysis are shown below. ¹ H-NMR (solvent: CDCl ₂ , standard: tetramethylsilane (TMS)) δ (ppm) = 6.9 to 8.5 (m, 26H: H of central biphenylene ring and carbazole ring) δ (ppm) = 4.3 (q, 4H: methylene (—CH ₂ —) of ethyl group) δ (ppm) = 1.4 (t, 6H: methyl of ethyl group (−)
CH ₃ -)) IR spectrum (KBr tablet ^{_{method) ν C = C; 1600cm -1}} ( stretching vibration of _{C = C) δ CH; 975cm} -1 ( out-of-plane deformation vibration of CH) Elemental analysis (in parentheses Is the theoretical value) C: 88.82% (89.15) H: 5.98% (6.12) N: 4.45% (4.73) Elemental composition: C ₄₄ H ₃₆ N ₂ Therefore, the obtained compound is

[0058]

[Chemical 29]

It was confirmed that

Synthesis Example 2

[0061]

[Chemical 30]

1.8 g of a phosphonate ester represented by is dissolved in 20 ml of DMSO under an argon atmosphere,
1.0 g of tBuOK was added. Then, 2.0 g of N-ethylcarbazole-3-carboxaldehyde was added, and the mixture was stirred at room temperature for 5 hours. 100 to the obtained reaction product
As a result of adding milliliter, a white powder was deposited. When a benzene solution containing I ₂ was added to this powder for recrystallization, 0.8 g of a white powder was obtained. The melting point of the obtained product was 237 to 238 ° C.

Further, proton nuclear magnetic resonance ( ¹ H-NM
The measurement results of R) spectrum, infrared absorption (IR) spectrum and elemental analysis are shown below. ¹ H-NMR (solvent: CDCl ₂ , standard: tetramethylsilane (TMS)) δ (ppm) = 6.9 to 8.1 (m, 28 H: H of aromatic ring and carbazole ring) δ (ppm) = 4.25 (q,
4H: methylene of ethyl group (—CH ₂ —)) δ (ppm) = 1.4 (t, 6H: methyl of ethyl group (−)
CH ₃ -)) IR spectrum (KBr tablet ^{_{method) ν C = C; 1600cm -1}} ( stretching vibration of _{C = C) δ CH; 975cm} -1 ( out-of-plane deformation vibration of CH) Elemental analysis (in parentheses Is the theoretical value) C: 86.53% (86.81) H: 5.72% (5.96) N: 4.32% (4.60) Elemental composition: C ₄₄ H ₃₆ N ₂ O From the results, the obtained compound is

[0064]

[Chemical 31]

It was confirmed that

Synthesis Examples 3 to 20 Phosphonates, aldehydes shown in Table 1 below,
The same reaction as in Synthesis Example 1 was performed except that a solvent and a base were used.

[0067]

[Table 1]

[0068]

[Table 2]

[0069]

[Table 3]

[0070]

[Table 4]

[0071]

[Table 5]

[0072]

[Table 6]

Reference Example 1 (Tolerance test of hole injection material) Hole injection materials (H1), (H2), (H) used in the present invention.
15), (H16) and other hole injection materials (see US Pat. No. 4,127,412), 1,1-bis (4-di-p-tolylaminophenyl) -cyclohexane (TPAC). The melting point and Tg of N, N, N ', N'-tetraphenyl-4,4'-diaminobiphenyl (TPD) are measured by a melting point measuring device and a differential scanning calorimeter (DS).
It measured using C). The results obtained are shown in Table 2.

[0074]

[Table 7]

Reference Example 2 (Measurement of Thermal Deterioration 1) A 25 mm × 75 mm × 1.1 mm glass substrate was ultrasonically cleaned with isopropyl alcohol for 3 minutes, and then,
The solvent was removed from the substrate surface by blowing dry nitrogen. Further, this glass substrate was treated with a UV / O ₃ dry stripper (manufactured by Samco International) for 3 minutes to remove organic substances on the substrate surface. This glass substrate was fixed to a substrate holder of a commercially available vapor deposition device (manufactured by Nippon Vacuum Technology Co., Ltd.), and a hole injection material (H
200 mg of 2) was added and the vacuum chamber was evacuated to 1.5 × 10 ⁻⁴ Pa. Then heat the boat to 330 ° C,
H2 was vapor-deposited on the transparent supporting substrate at a vapor deposition rate of 0.1 to 0.3 nm / sec to form a layer having a thickness of 60 nm. The substrate temperature at this time was room temperature. As a result of leaving the obtained thin film in the air, it was confirmed that recrystallization did not occur even after 3 weeks.

Reference Example 3 (Measurement of Thermal Degradation 2) A film was formed in the same manner as in Reference Example 2 except that 200 mg of TPD was put in a resistance heating boat made of molybdenum and the boat was heated to 220 ° C. As a result of leaving the obtained thin film in the air, after about 2 weeks, a cloudy point began to appear in the transparent thin film. Observation of this cloudy point with an optical microscope revealed that it was crystal growth, and it was found that recrystallization occurred. From the results obtained in Reference Examples 1 to 3 above, it can be seen that the hole injection material used in the present invention has a high melting point and Tg, and a small thermal deterioration.

Example 1 ITO was formed on a glass substrate of 25 mm × 75 mm × 1.1 mm.
A film formed by vapor deposition to a thickness of 100 nm (HOY
A product) was used as a transparent support substrate. Next, this transparent supporting substrate was ultrasonically cleaned in order using propyl alcohol, pure water and isopropyl alcohol, and then dry nitrogen was blown to remove the solvent from the substrate surface. Further, this transparent supporting substrate was treated with a UV / O ₃ dry stripper (manufactured by Samco International) for 3 minutes to remove organic substances on the substrate surface. This transparent support substrate was fixed to a substrate holder of a commercially available vapor deposition device (manufactured by Japan Vacuum Technology Co., Ltd.), 200 mg of Al complex (Alq) of 8-hydroxyquinoline was put in a resistance heating boat made of molybdenum, and another molybdenum product was made. Hole injection material (H2: BCzVBi) 200m in the boat
g, and the vacuum chamber was evacuated to 1 × 10 ⁻⁴ Pa. After that, the boat containing H2 is heated to 330 ° C.
Was vapor-deposited on the transparent supporting substrate at a vapor deposition rate of 0.1 to 0.3 nm / sec to form a hole injection layer having a film thickness of 60 nm. The substrate temperature at this time was room temperature. Next, without taking this out from the vacuum chamber, Alq was laminated and vapor-deposited to a thickness of 50 nm on the hole injection layer from another boat as a light emitting layer. At this time, the boat temperature is 240 to 250 ° C, and the vapor deposition rate is 0.2.
˜0.4 nm / sec, the substrate temperature was room temperature. The obtained laminate was taken out of the vacuum chamber, a stainless steel mask was set, and the substrate was again fixed to the substrate holder. Next, 1 g of a magnesium ribbon was placed in a resistance heating boat made of molybden, and 500 mg of Ag was attached to another resistance heating filament made of tungsten. Then, the vacuum chamber is set to 2 x 10
^{-Decompress to -4} Pa, heat the above boat to deposit Ag.
Magnesium was vapor-deposited at a vapor deposition rate of 1-2 nm / sec by heating the other boat at the same time of 0.1-0.2 nm / sec. In this way, a mixed metal electrode of magnesium and Ag was laminated and vapor-deposited on the light emitting layer in a thickness of 150 nm to form a counter electrode. A DC current of 8 V was applied using the mixed metal electrode as a cathode and the ITO electrode as an anode, and as a result, a current of about 23 mA / cm ² flowed and a uniform green light was obtained. As a result of the spectroscopic measurement, the emission luminance is 700 cd.
/ M ² , and the luminous efficiency was 1.2 lumen / W. Also,
As a result of carrying out a life test on this element in a nitrogen gas atmosphere, the half-life at an initial luminance of 100 cd / m ² was 600 hours.

Examples 2 to 19 Organic EL devices were prepared in the same manner as in Example 1 except that the compounds shown in Table 3 were used as the hole injection material. The result of the evaluation test conducted in the same manner as in Example 1 is the third.
Shown in the table.

[0079]

[Table 8]

Comparative Example 1 ITO was formed on a glass substrate of 25 mm × 75 mm × 1.1 mm.
A film formed by vapor deposition to a thickness of 100 nm (HOY
A product) was used as a transparent support substrate. Next, this transparent supporting substrate was ultrasonically cleaned in order using propyl alcohol, pure water and isopropyl alcohol, and then dry nitrogen was blown to remove the solvent from the substrate surface. Further, this transparent supporting substrate was treated with a UV / O ₃ dry stripper (manufactured by Samco International) for 3 minutes to remove organic substances on the substrate surface. This transparent support substrate was fixed to a substrate holder of a commercially available vapor deposition device (manufactured by Japan Vacuum Technology Co., Ltd.), 200 mg of TPD was put in a resistance heating boat made of molybdenum, and 200 mg of Alq was put in another molybdenum boat to make a vacuum chamber. Was reduced to 1 × 10 ⁻⁴ Pa. Then, the boat containing TPD is heated to 220 ° C., and the deposition rate of TPD is reduced to 0.2.
Deposition is performed on a transparent supporting substrate at a film thickness of 1 to 0.3 nm / sec.
A 0 nm hole injection layer was formed. The substrate temperature at this time was room temperature. Next, without taking this out from the vacuum chamber, Alq was laminated and vapor-deposited to a thickness of 50 nm on the hole injection layer from another boat as a light emitting layer. At this time, the boat temperature is 240 to 250 ° C, and the vapor deposition rate is 0.2 to 0.4 nm /
Second, the substrate temperature was room temperature. Take out the obtained laminate from the vacuum chamber, install a stainless steel mask,
It was fixed to the substrate holder again. Next, put 1g of magnesium ribbon into a molybdenum resistance heating boat and add 500m Ag to another tungsten resistance heating filament.
g was attached. After that, the vacuum chamber was decompressed to 2 × 10 ⁻⁴ Pa, the boat was heated, and Ag was deposited at a deposition rate of 0.1 to 0.2
The other boat was also heated at the same time for m / sec to deposit magnesium at a deposition rate of 1 to 2 nm / sec. In this way, a mixed metal electrode of magnesium and Ag is formed on the light emitting layer.
A 50 nm laminated vapor deposition was carried out to form a counter electrode. A DC voltage of 6 V was applied using the mixed metal electrode as a cathode and the ITO electrode as an anode. As a result, an electric current of about 32 mA / cm ² flowed and a uniform green light was obtained. As a result of the spectroscopic measurement, the emission luminance was 900 cd / m ² and the emission efficiency was 1.5 lumen / W. Further, as a result of performing a life test on this element in a nitrogen gas atmosphere, the half-life at an initial luminance of 100 cd / m ² was 100 hours. This comparative example is excellent in the initial luminous efficiency, but has a drawback that the device life is short due to deterioration due to energization and thermal deterioration.

[0081]

As described above, the organic EL device of the present invention is
It prevents the energization deterioration, the thermal deterioration and the pinhole formation and enables the life of the element to be extended. Therefore, the organic EL element of the present invention is expected to be effectively used as a display element for various devices, a display element such as a light emitting element.

Claims (2)

[Claims] 1. A compound represented by the general formula (I): (In the formula, R ¹ and R ² each independently have 1 to 1 carbon atoms.
0 alkyl group, C 6-20 aryl group, C 6-20 alkyl group-substituted aryl group, C 6-20
Aryloxy group-substituted aryl group having 6 to 2 carbon atoms
And 0 represents an aryl group substituted with an alkoxy group. R ⁷ and R
⁸ independently represents hydrogen, an alkyl group having 1 to 10 carbon atoms, an aryl group having 6 to 20 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, or an aryloxy group having 6 to 20 carbon atoms. In addition, X is the formula (Here, R ^{3 to} R ⁶ are independently hydrogen and a carbon number of 1
It shows an alkyl group having 10 to 10 or an alkoxy group having 1 to 10 carbon atoms. ) Is a divalent group. ) Or general formula (II) (In the formula, R ¹ , R ² , R ⁷ , R ⁸ and X are the same as the above.) An organic electroluminescence device using a compound as a hole injection material. 2. An organic electroluminescent device using a thin film made of the compound according to claim 1 as a hole injection layer.