JPH1180111A - Enamine group-containing hydrazone derivative and electroluminescent element using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new compound, useful as a material for an electroluminescent element such as a hole injecting transport material and capable of providing the electroluminescent element, having a low driving voltage and manifesting a good luminous efficiency. SOLUTION: This compound is represented by formula I Q is (CH2 )m [(m) is 0-4] or a(n) (un)substituted arylene; R<1> and R<2> are each H, an alkyl or a(n) (un)substituted aryl; R<3> and R<4> are each an alkyl or a(n) (un)substituted aryl ; R<5> is a(n) (un) substituted aryl ; R<6> is a(n) (un)substituted aryl, an alkyl or H}, e.g. a compound represented by formula II. The compound represented by formula I is obtained by reacting, e.g. a hydrazone compound represented by formula III with 2-5 equiv. aldehyde compound represented by formula IV in an aromatic solvent such as benzene or toluene using an organic acid such as p-toluenesulfonic acid as a catalyst under heating and refluxing and removing water which is a by-product from the reactional system.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a novel hydrazone derivative containing two enamine groups. Further, the present invention provides a luminescent material comprising the hydrazone derivative,
The present invention relates to a material for an electroluminescent element such as a hole injecting / transporting material, and an electroluminescent element using the hydrazone derivative, which has a low driving voltage and good luminous efficiency.

[0002]

2. Description of the Related Art An electroluminescent device (EL device) has features such as high visual recognition of self-luminescence and excellent impact resistance because it is a completely solid device. Because of these features, the use of EL elements in various display devices, backlight lamps, and the like has recently attracted attention.

[0003] The EL element includes an inorganic EL element using an inorganic compound for a light emitting layer and an organic EL element using an organic compound. Particularly, organic EL devices have been actively studied for practical application in order to reduce the applied voltage and support full color.

[0004] Regarding the structure of the organic EL element, the basic structure of the anode / light-emitting layer / cathode includes a hole injection / transport layer having a function of efficiently transmitting holes injected from the anode to the light-emitting layer.
Alternatively, a structure in which an electron injection / transport layer having a function of efficiently transmitting electrons injected from a cathode to a light emitting layer is appropriately provided is well known. For example, US Pat. No. 4,539,
507, U.S. Pat. No. 4,769,299,
JP-A-9-194393 and JP-A-63-29556
No. 95 discloses various organic EL devices having a structure of anode / hole injection / transport layer / light emitting layer / cathode. In the organic EL device having this configuration, the total thickness of the hole injecting and transporting layer and the light emitting layer can be reduced to 150 nm or less by using a material that can easily form a thin film in the hole injecting and transporting layer.
As a result, high-luminance light emission has been successfully obtained with a drive voltage of 20 V or less. Further, Appl. Phys. L
ett. 51, 913 (1987) discloses that a hole injection / transport layer uses a triphenylamine-based hole transfer compound capable of acting as a barrier to electrons and is present at the interface between the hole injection / transport layer and the light emitting layer. The electron barrier accumulates electrons at the interface of the light-emitting layer, thereby increasing the luminous efficiency.
It discloses that green light emission of high luminance of 10 ³ cd / m ² was realized at an efficiency of 1.5 (lm / V) with the following applied voltage.

On the other hand, an EL element that emits light by recombination of electrons and holes should theoretically be able to be driven by a low voltage (about 2 to 6 V) comparable to a light emitting diode. However, at present, the driving voltage of the EL element is 6
V or more. This is due to the energy barrier for hole injection at the interface between the anode and the hole injection / transport layer or the interface between the hole injection / transport layer and the light emitting layer, or the energy for the electron injection at the interface between the light emitting layer and the cathode. Because of the barrier. Further, it is said that the theoretical upper limit of the emission quantum yield is close to 40%, but in the current EL device,
Only a quantum yield of about 3% has been obtained. As described above, in the organic EL device having the structure of the anode / hole injection / transport layer / light emitting layer / cathode, although the performance is better than the EL devices having other configurations, the driving voltage and the luminous efficiency are not necessarily sufficient. Is not satisfactory.

Further, the material of the organic EL element is inorganic EL.
It is inferior in durability to the element, and therefore is not suitable for long-time use.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic compound for an EL device which satisfies high luminous efficiency, high-luminance luminescence and low driving voltage.

[0008] It is a further object of the present invention to provide an organic EL device which satisfies good luminous efficiency, high-luminance luminescence and low driving voltage.
An L element is to be provided.

A further object of the present invention is to provide an organic EL device which has a small chemical degradation due to environmental substances such as water and oxygen, a small physical degradation due to light, heat and the like, and a long life.

[0010]

The present inventor has synthesized various organic compound materials in order to develop an EL device having the above-mentioned excellent characteristics, and tested the characteristics thereof. It has been found that the novel hydrazone derivative shows excellent properties as at least a hole injection transport material and a light emitting material.

According to the present invention, the formula

[0012]

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(Wherein Q represents-(CH ₂ ) _m -or a substituted or unsubstituted arylene group, m represents an integer of 0 to 4, and R ¹ and R ² each represent a hydrogen atom, an alkyl group or R ³ and R ⁴ each represent an alkyl group or a substituted or unsubstituted aryl group; R ⁵ represents a substituted or unsubstituted aryl group; and R ⁶ represents a substituted or unsubstituted aryl group. A hydrazone derivative containing two enamine groups represented by a substituted aryl group, an alkyl group or a hydrogen atom) is provided.

According to a preferred embodiment of the present invention, the formula

[0015]

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Wherein R ³ , R ⁴ and R ⁶ are as defined above, R ³ and R ⁴ are the same, and R ⁷ is a halogen atom, a lower alkoxy group, a lower alkyl group or a hydrogen atom And n represents an integer of 1 to 3).

Further according to the present invention, the formula

[0018]

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Wherein Q, R ¹ , R ² , R ³ and R ⁴
Is as defined above, and R ⁸ and R ⁹ each represent a hydrogen atom, a lower alkyl group or a substituted or unsubstituted aryl group, or R ⁸ and R ⁹ are substituted or unsubstituted together with two carbon atoms of the cycloalkane. A hydrazone derivative containing two enamine groups is provided, which forms part of a substituted aromatic hydrocarbon and r represents an integer from 3 to 6.

Further according to a preferred embodiment of the present invention,

[0021]

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[0022] (wherein, R ^1, R ^2, R ³ and R ⁴ are as defined above, which is the same as R ¹ and R ^2, R ³
And R ⁴ are the same, and R ¹⁰ represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a halogen atom, and s represents an integer of 1 to 3). .

Further according to the present invention, the formula

[0024]

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Wherein R ¹ , R ² , R ³ , R ⁴ and s
Is as defined above, and R ¹ and R ² are the same,
R ³ and R ⁴ are the same, and X is an oxygen atom, a sulfur atom or

[0026]

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[0027] represents, R ¹³ represents and t represents 0 or 1 hydrogen atom or a lower alkyl group, and R ¹¹
And R ¹² each represent a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group), and a hydrazone derivative containing two enamine groups is provided.

Further according to a preferred embodiment of the present invention,

[0029]

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Wherein R ¹ , R ² , R ³ , R ⁴ and s
Is as defined above, and R ¹ and R ² are the same,
And R ³ and R ⁴ are the same).

In the compound of the above formula, the alkyl group includes
Lower alkyl groups are preferably used, for example, having 1 to 4 carbon atoms including methyl, ethyl, propyl and butyl.
Is preferably used. In the compounds of the above formula, for the lower alkyl group, for example, an alkyl group having 1 to 4 carbon atoms including methyl, ethyl, propyl and butyl is preferably used, and for the lower alkoxy group, methoxy, ethoxy, propoxy, butoxy A C1-C4 alkoxy group containing is preferably used. Examples of the halogen atom include chlorine, bromine and iodine.

The present inventors have found that, in an EL device having a basic structure of anode / light-emitting layer / cathode, the compound of the above formula exhibits excellent properties as a hole injection / transport material or a light-emitting material. The compound of the above formula reduces the energy barrier and enables a lower driving voltage in the EL device. Further, the compound of the above formula can provide high luminous efficiency. Further, the compound of the above formula is an EL which operates stably for a long time.
An element can be provided.

Therefore, according to the present invention, there is provided a hole injecting / transporting material for an EL device comprising a hydrazone derivative represented by any of the general formulas (I) to (VI).

According to the present invention, the compounds represented by the general formulas (I) to (V)
There is provided a light emitting material for an EL device comprising the hydrazone derivative represented by any one of I).

Further, according to the present invention, there is provided an EL device using the compound of the above general formula. According to the present invention, in an EL device in which an anode, a hole injecting and transporting layer, a light emitting layer, and a cathode are sequentially stacked, the hole injecting and transporting layer or the light emitting layer is represented by any one of formulas (I) to (VI). A device containing the derivative is provided.

Further, according to the present invention, in an EL device in which an anode, a hole injecting and transporting layer, a light emitting layer, an electron transporting layer and a cathode are laminated in this order, the hole injecting and transporting layer or the light emitting layer has the general formula (I) to (VI) And a device containing the hydrazone derivative represented by any one of the above.

Furthermore, the present inventor has found that the luminous efficiency is further improved by providing a charge blocking layer in an EL device using the compound of the above formula. Therefore, according to the present invention, there is provided an EL device further comprising a charge barrier layer between the anode and the cathode. The charge barrier layer is preferably an electron barrier layer.

[0038]

DETAILED DESCRIPTION OF THE INVENTION A hydrazone compound containing two enamine groups according to the present invention is prepared by the following synthetic route. In the synthesis of the compounds of the general formulas (I) to (VI), first, an aldehyde compound or a ketone compound represented by the general formula (VII) and a compound of the general formula (VIII-
The hydrazine compound represented by formula (IX) is obtained by heating and refluxing a) and the hydrazine compound represented by formula (VIII-b) in a solvent under acidic conditions. Formulas (VIII-a) and (VIII)
-B) the compounds of general formula (VII)
Can be heated and refluxed. The above reaction is
It is represented by the following equation.

[0039]

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Wherein Q, R ¹ , R ² , R ³ and R ⁴
Has the same meaning as described above, R ¹ and R ² may be the same or different, and R ³ and R ⁴ may be the same or different. ) And (II),
The obtained hydrazone compound (IX) is mixed with 2 to 5 equivalents of the aldehyde compound represented by the general formula (X) in an aromatic solvent such as benzene or toluene using an organic acid such as p-toluenesulfonic acid as a catalyst. The reaction is performed by heating to reflux. By removing water as a by-product from the reaction system, a hydrazone compound represented by the general formula (I) or (II) can be easily obtained. This reaction is represented by the following reaction formula.

[0041]

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(Wherein Q, R ¹ , R ² , R ³ , R ⁴ , R
⁵ and R ⁶ are as defined above, and R ¹ and R ² may be the same or different, and R ³ and R ⁴ may be the same or different. General formula (III) When preparing the compound represented by (IV) and (IV), the resulting hydrazone compound (IX)
The reaction is carried out by heating to reflux 5 to 5 equivalents of the aldehyde compound represented by the general formula (XI) in an aromatic solvent such as benzene or toluene using an organic acid such as acetic acid or p-toluenesulfonic acid as a catalyst. Let it. By removing water as a by-product from the reaction system, a hydrazone compound represented by the general formula (III) or (IV) can be easily obtained.
This reaction is represented by the following reaction formula.

[0043]

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(Wherein Q, R ¹ , R ² , R ³ , R ⁴ , R
⁸ , R ⁹ and r are as defined above, and R ¹ and R ² may be the same or different, and R ³ and R ⁴ may be the same or different.) General formulas (V) and ( When preparing the compound of VI),
To the obtained hydrazone compound (IX), 2 to 5 equivalents of the aldehyde compound represented by the general formula (XII) is added with acetic acid,
The reaction is carried out by heating and refluxing in an aromatic solvent such as benzene or toluene using an organic acid such as p-toluenesulfonic acid as a catalyst. By removing water as a by-product from the reaction system, the hydrazone compound represented by the general formula (V) or (VI) can be easily obtained. This reaction is represented by the following reaction formula.

[0045]

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(Wherein R ¹ , R ² , R ³ , R ⁴ , R ¹¹ ,
R ¹² and X are as defined above, and R ¹ and R ² may be the same or different, and R ³ and R ⁴ may be the same or different. According to the above process, for example, Synthesized.

The hydrazone compounds corresponding to the general formula (I) or (II) are exemplified below. Compound 1

[0048]

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Compound 2

[0050]

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Compound 3

[0052]

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Compound 4

[0054]

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Compound 5

[0056]

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Compound 6

[0058]

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Compound 7

[0060]

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Compound 8

[0062]

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Compound 9

[0064]

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Compound 10

[0066]

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Compound 11

[0068]

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Compound 12

[0070]

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Compound 13

[0072]

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Compound 14

[0074]

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Compound 15

[0076]

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Compound 16

[0078]

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Compound 17

[0080]

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Compound 18

[0082]

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Compound 19

[0084]

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Compound 20

[0086]

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Compound 21

[0088]

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Compound 22

[0090]

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Compound 23

[0092]

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Compound 24

[0094]

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Compound 25

[0096]

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Compound 26

[0098]

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Compound 27

[0100]

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Compound 28

[0102]

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Compound 29

[0104]

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Compound 30

[0106]

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Compound 31

[0108]

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Compound 32

[0110]

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Compound 33

[0112]

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Compound 34

[0114]

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Compound 35

[0116]

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Compound 36

[0118]

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Among these, compounds 6, 9, 10, 1
3, 16, 26 and 32 have the general formulas (I) and (I)
This corresponds to both of I).

Compounds 1, 4, 8, 10, 13, 20, 2
Except for 3, 29, 30 and 35, the remaining other hydrazone compounds have melting points above 200 ° C. The hydrazone compound having such a high melting point is difficult to be separated by recrystallization or column chromatography using a common organic solvent (for example, toluene, ethyl acetate, methyl ethyl ketone, alcohol, etc.), and thus N, N-
Purification was performed by reprecipitation or sublimation using a special solvent such as dimethylformamide (DMF). In the identification of these compounds, the infrared absorption spectrum (IR
Spectrum), NMR spectrum, elemental analysis, mass spectrometry and the like. Mass spectrometry was the most reliable in identification.

The methods of synthesizing compounds according to the present invention will be described in more detail by showing more detailed synthetic processes for some of the above compounds.

Synthesis Example 1 (Production of Compound 19) 4,4'-Diacetylbiphenyl (melting point: 194.5 to 1)
96.0 ° C.) 2.4 g, 10 g of phenylhydrazine and a small amount of acetic acid are added to 200 ml of n-butyl alcohol. The resulting mixture is heated at reflux in an oil bath for about 10 hours,
4,4'-di (acetyl-N-phenylhydrazono)-
3.4 g of a yellow-white powder of biphenyl are obtained. The product is I
Identified by R spectrum and mass spectrometry.

IR spectrum: (KBr tablet, cm ^-1 )
3246 (Aromatic secondary amine) Mass spec: (m / z) 418 NMR spectrum: (CDCl ₃ , δ value, ppm)
15 to 1.55 (6H, m, CH ₃ ) 2.2 g of the obtained hydrazone compound was added to benzene 1
In 100 ml, to which 4.4 g of diphenylacetaldehyde (oil) are added, followed by a trace amount of p-toluenesulfonic acid as a dehydrating agent. Using a Soxhlet extractor, the resulting mixture is heated to reflux in an oil bath for about 5 hours while adsorbing by-product water on anhydrous sodium sulfate. After distilling off benzene, the precipitated yellow-orange powder is thoroughly washed with water. The powder is then dissolved in 50 ml of dimethylformamide and the insolubles are removed. Next, the obtained solution is added to 300 ml of an ethyl alcohol solution, and the precipitated powder is taken out. Take out the extracted powder with hot acetone 5
After washing with 0 ml, 2.4 g of compound 19 (mp 295-296.5 ° C.) are obtained. For the compound obtained, the absorption based on the secondary amine at 3246 cm ^-1 in the IR spectrum disappears. Mass spectrometry shows a parent peak at 774 for this compound.

Synthesis Example 2 (Production of Compound 16) 6.7 g of terephthalaldehyde, 6.7 g of phenylhydrazine and 0.5 ml of acetic acid are added to ethanol.
The obtained mixture is heated and refluxed for 3 hours to obtain 10.2 g of precipitated yellow-white needle-like crystals.

IR spectrum: (KBr tablet, cm ^-1 )
3295 (Aromatic secondary amine) Mass spec: (m / z) 314 NMR spectrum: (CDCl ₃ , δ value, ppm)
_{13 (5H, m, C 6} H 5) thus obtained p-N, N'-diphenyl - dissolved di hydrazono benzene 3.1g and diphenylacetaldehyde 8g benzene 50 ml, a small amount of acetic acid to Add. The obtained mixture is heated and refluxed for 5 hours in a glass container having a trap filled with anhydrous sodium sulfate. After distilling off benzene, the precipitated yellow powder was recrystallized in toluene to give yellow-brown needle-like crystals.
2 g are obtained. (Compound 16) melting point 238.5-240
C, mass spectrometry: (m / z) 670 Synthesis Example 3 (Production of Compound 26) In the same manner as in Synthesis Example 1, 4,4'-diformylbiphenyl was reacted with α-hydrazinonaphthalene to give 4,
4'-di (formyl-N-α-naphthylhydrazino)-
A yellow powder of biphenyl is obtained. Next, the obtained compound is reacted with diphenylacetaldehyde to obtain a red-orange compound 26. 303-306 ° C.

Synthesis Example 4 (Production of Compound 15) A yellow-brown compound 15 is obtained in the same manner as in Synthesis Example 3, except that 2,4-dimethylterephthalaldehyde is used instead of 4,4'-diformylbiphenyl. Melting point 261.5
~ 264 ° C.

Other compounds can be synthesized according to the above synthesis examples. The compounds according to the invention have a relatively high melting point and thermal stability. Compounds 1 to 3
No. 6 shows strong blue to orange light emission with respect to ultraviolet light.

Tables 1 to 6 summarize the reaction conditions and analytical values for Compounds 1 to 36.

[0129]

[Table 1]

[0130]

[Table 2]

[0131]

[Table 3]

[0132]

[Table 4]

[0133]

[Table 5]

[0134]

[Table 6]

The appearance (colored state) of each of Compounds 1 to 36 was visually confirmed. Further, 355 nm was added to a tablet obtained by pressing each of Compounds 1 to 36 into a disk shape.
Irradiation with ultraviolet light of ± 2 nm was performed, and the maximum wavelength of the resulting fluorescence was measured. Tables 7 and 8 show the results.

[0136]

[Table 7]

[0137]

[Table 8]

From the table, it can be seen that the hydrazone compound according to the present invention is a PL (ultraviolet light emitting) material exhibiting blue to green fluorescence in the range of 425 nm to 550 nm. Among these compounds, compounds 6, 7, 15, 1
6, 17 and 18 show particularly intense blue emission.

The thermal decomposition temperatures of four hydrazone compounds, Compounds 6, 7, 16 emitting strong blue light and Compound 26 emitting strong green light, were measured by differential thermal analysis. Further, the degree of coloring of each material in a molten state was visually examined. Table 9 shows the results. As shown in the table,
It can be seen that the hydrazone compound according to the present invention has excellent thermal stability.

[0140]

[Table 9]

Further, compounds corresponding to the general formula (III) or (IV) are exemplified below. Compound 37

[0142]

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Compound 38

[0144]

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Compound 39

[0146]

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Compound 40

[0148]

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Compound 41

[0150]

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Compound 42

[0152]

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Compound 43

[0154]

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Compound 44

[0156]

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Compound 45

[0158]

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Compound 46

[0160]

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Compound 47

[0162]

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Compound 48

[0164]

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Compound 49

[0166]

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Compound 50

[0168]

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Compound 51

[0170]

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Compound 52

[0172]

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Compound 53

[0174]

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Compound 54

[0176]

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Compound 55

[0178]

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Compound 56

[0180]

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Compound 57

[0182]

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Compound 58

[0184]

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Compound 59

[0186]

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Of these compounds, compounds 38, 3
9, 41, 45, 47, 49, 52, 56, and 58
Corresponds to both general formulas (III) and (IV).

Further, the compounds corresponding to the general formula (V) or (VI) are exemplified below. Compound 60

[0189]

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Compound 61

[0191]

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Compound 62

[0193]

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Compound 63

[0195]

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Compound 64

[0197]

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Compound 65

[0199]

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Compound 66

[0201]

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Compound 67

[0203]

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Compound 68

[0205]

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Compound 69

[0207]

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Compound 70

[0209]

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Compound 71

[0211]

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Compound 72

[0213]

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Compound 73

[0215]

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Compound 74

[0219]

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Of these compounds, compounds 63 and 6
5, 67, 70, 73 and 74 correspond to both general formulas (V) and (VI).

Of compounds 37 to 74, compounds 38 and 4
The melting points of the compounds excluding 0 and 43 are 200 ° C. or higher. Accordingly, the glass transition point of most compounds is 1
Exceeds 00 ° C. Therefore, a compound having a relatively high melting point and a glass transition point is particularly excellent in thermal stability. In particular, compounds 39, 42, 44, 46, 5
2, 54, 58 and compounds 63 to 74 are excellent not only in terms of thermal stability but also in terms of the synthesis process.

Since many of the above-mentioned hydrazone compounds have poor solubility in ordinary organic solvents (eg, toluene, alcohol, ethyl acetate), recrystallization of hydrazone compounds using ordinary organic solvents or Separation by column column chromatography is relatively difficult.
Therefore, it is preferable to purify the hydrazone compound by recrystallization or reprecipitation in a specific organic solvent such as dimethylformamide or dimethylsulfoxide, or by sublimation. These compounds are mainly identified by IR spectrum, elemental analysis and mass spectrometry.

A specific example using a typical synthesis process will be described in detail below. Synthesis Example 5 (Production of Compound 39) 13.4 g of terephthalaldehyde and 25.0 g of phenylhydrazine are dissolved in 100 ml of ethanol, and 2 drops of glacial acetic acid are added thereto. The obtained mixture is heated under reflux for about 1 hour to obtain 24.5 g of precipitated yellow needle crystals. From the measurement of the IR spectrum, while absorbing the aldehydes of 1690 cm ^-1 disappears, confirms that the absorption of the aromatic secondary amine occurs 1310cm ^-1. By this reaction, a bishydrazone represented by the following structural formula is generated.

[0222]

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6.3 g of the obtained bishydrazone compound and 10 g of 1,2,3,4-tetrahydronaphthalene-1-carbaldehyde were dissolved in 150 ml of benzene.
To this is added a small amount of p-toluenesulfonic acid. The obtained mixture is heated and refluxed by a Dean-Stark reactor, and the reaction is carried out while removing water as a by-product out of the system until generation of water is no longer observed. After the reaction, benzene is removed, and the precipitated yellowish white powder is washed with alcohol. Recrystallization with ethyl acetate gives 7.8 g of crystals (compound 39). 253.5-256 ° C.
From the IR spectrum, 1310 cm ⁻¹ and 3470 c
It is confirmed that the absorption based on the aromatic secondary amine around m ^-1 disappears. Mass spectrometry value: (as C ₄₂ H ₃₈ N ₄
m / z) 598. The obtained compound 39 shows sky blue fluorescence.

[0224] Other bishydrazone compounds are synthesized in the same manner. Tables 10 to 13 summarize the reaction conditions, analysis values, presence / absence of fluorescence, and fluorescence color of Compounds 37 to 59.

[0225]

[Table 10]

[0226]

[Table 11]

[0227]

[Table 12]

[0228]

[Table 13]

The bishydrazone compound represented by the general formula (V) or (VI) is also synthesized by substantially the same process as in Synthesis Example 5. Since the reaction proceeds relatively slowly, it is preferable that the reaction time is relatively long or the reaction temperature is relatively high. As the dehydrating agent, titanium tetrachloride or the like is more preferable than an organic acid such as p-toluenesulfonic acid. Tables 14 to 1 show the reaction conditions, analytical values, the presence or absence of fluorescence, and the color tone of the fluorescent color for Compounds 60 to 74.
Summarize in 6.

[0230]

[Table 14]

[0231]

[Table 15]

[0232]

[Table 16]

The purification of compounds 37 to 74 is generally achieved by recrystallization in a solvent such as dimethylformamide, dimethylsulfoxide and the like. If the purity of the obtained crystals is not sufficient, a sublimation purification method is applied. In particular, in the purification of compounds 60 to 74, the sublimation method is more preferable.

The structure of the EL device according to the present invention will be described below. The organic EL device according to the present invention has a basic structure of anode / light-emitting layer / cathode. A hole injection transport layer and / or an electron injection transport layer can be added to this basic structure. Further, it is preferable to provide a charge barrier layer as needed. The charge blocking layer can be provided as an electron blocking layer, a hole blocking layer, or both. When the charge barrier layer is an electron barrier layer, it is provided between the light emitting layer and the anode, preferably in contact with the anode side surface of the light emitting layer. On the other hand, when the charge blocking layer is a hole blocking layer, it is provided between the light emitting layer and the cathode, preferably in contact with the cathode side surface of the light emitting layer.

A typical structure of an EL device having a charge blocking layer is shown below. Element structure 1: anode / hole injection / transport layer / electron barrier layer / emission layer / cathode Element structure 2: anode / emission layer / hole barrier layer / electron injection / transport layer / cathode Element structure 3: anode / hole injection / transport Layer / Electronic Barrier Layer / Emitting Layer / Hole Barrier Layer / Electron Injection / Transport Layer / Cathode A buffer layer may be provided between the electrode and the organic material layer and / or between a plurality of organic material layers. The buffer layer can contribute to prevention of delamination and improvement of hole or electron injection efficiency. Materials for the buffer layer include various phthalocyanine pigments, various organic metal salts such as trialkoxyaluminum, zinc stearate, indium acetylacetonate, magnesium acetylacetone, and carbon black. The thickness of the buffer layer is 10 to 1000 nm, preferably 10 to 5 nm.
00 nm, more preferably 50 to 500 nm. The thickness of the buffer layer slightly changes depending on the position where the buffer layer is provided. The buffer layer is provided at a position where peeling easily occurs. For example, in the case of the element structure 1, the preferred positions are between the anode and the hole injection / transport layer and between the light emitting layer and the cathode. In the case of the element structure 2, preferred positions are between the anode and the light emitting layer and between the electron injection / transport layer and the cathode. In the case of the device structure 3, the positions between the anode and the hole injection / transport layer and between the electron injection / transport layer and the cathode are preferred positions for the buffer layer.

The above-described element structure is preferably supported on a substrate. As the substrate, there is no particular limitation, and a substrate usually used for an organic EL element, for example, glass, transparent plastic, quartz or the like can be used.

As the number of layers constituting the element increases, the control of the manufacturing process becomes more difficult, and problems such as peeling increase. Therefore, it is preferable to obtain an element having a higher luminous efficiency and a lower driving voltage with a simpler structure.

The hydrazone compound according to the present invention can be used as a main material of a hole injection / transport layer or a main material of a light emitting layer. Further, by using the compound according to the present invention together with another light emitting layer material or transport layer material,
An organic EL element which emits light with high luminance at a lower driving voltage and better luminous efficiency can be obtained. Other organic materials include the following compounds.

As other light emitting materials, for example, polycyclic fused aromatic compounds, benzothiazole, benzimidazole,
A fluorescent whitening agent such as benzoxazole, a metal chelated oxinoid compound, a styrylbenzene-based compound, or the like can be used. Examples of the polycyclic condensed aromatic compound include an anthracene, naphthalene, phenanthrene, pyrene, chrysene, condensed ring light-emitting substance containing a perylene skeleton, and other condensed ring light-emitting substances containing about eight condensed rings. As the fluorescent whitening agent, for example, those described in JP-A-59-194393 can be used. A typical example is 2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) -1,3,3.
4-thiadiazole, 4,4'-bis (5,7-t-pentyl-2-benzooxazolyl) stilbene, 4,
4'-bis [5,7-di- (2-methyl-2-butyl)
-2-benzoxazolyl] stilbene, 2,5-bis (5,7-di-t-pentyl-2-benzooxazolyl) thiophene, 2,5-bis [5- (α, α-dimethylbenzyl) ) -2-Benzoxazolyl] thiophene,
2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzooxazolyl] -3,4-diphenylthiophene, 2,5-bis (5-methyl-2-benzo Oxazolyl) thiophene, 4,4'-bis (2-benzoxazolyl) biphenyl, 5-methyl-2- [2-
Benzoxazole-based compounds such as [4- (5-methyl-2-benzooxazolyl) phenyl] vinyl] benzoxazole and 2- [2- (4-chlorophenyl) vinyl] naphtho (1,2-d) oxazole; 2,2'-
Benzothiazole compounds such as (p-phenylenedivinylene) -bisbenzothiazole, 2- [2- [4-
(2-benzimidazolyl) phenyl] vinyl] benzimidazole, 2- [2- (4-carboxyphenyl)
Vinyl] benzimidazole and the like.

As the metal chelated oxinoid compound, for example, those described in JP-A-63-29569 can be used. Typical examples are tris (8-quinolinol) aluminum, bis (8-quinolinol) magnesium, bis (benzo [f] -8-quinolinol) zinc, bis (2-methyl-8-quinolinolate) aluminum oxide, tris (8 -Quinolinol) indium, tris (5-methyl-8-quinolinol) aluminum, lithium 8-quinolinol, tris (5-chloro-8-quinolinol) gallium, bis (5
-Chloro-8-quinolinol) calcium, poly [zinc (II) -bis (8-hydroxy-5-quinolinonyl)]
[Methane]] and dilithium epindridione.

Further, in addition to the above compounds, for example, 12
-Phthaloberinone (Journal of Applied Physics, J. Appl. Phys.), Vol. 27, L.
713 (1988), stilbene compounds (Japanese Patent Application No.
No. 2-312356, Japanese Patent Application No. 63-80257, Japanese Patent Application No. 63-313932, and Japanese Patent Application No. 63-308859) can also be used for the light emitting layer.

When the hydrazone compound according to the present invention is used in a light-emitting layer, an organic compound having an electron-transporting property, which is capable of exhibiting a function of transferring electrons injected from a cathode to the light-emitting layer, is used as an electron-transporting material. Can be used. Such an organic electron transfer compound is not particularly limited, and any compound can be selected from known compounds. Preferred organic electron transfer compounds include:

[0243]

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[0244]

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A nitro-substituted fluorenone derivative such as

[0246]

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Thiopyran dioxide derivatives such as

[0248]

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Diphenylquinone derivatives (described in Polymer Preprints, Japan, Vol. 37, No. 3, p. 681 (1988), etc.);

[0250]

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[0251]

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Compounds such as those described in Journal of Applied Physics (J. Appl. Phys.), Vol. 27, L269 (1988), etc., and anthraquinodimethane derivatives (JP-A-57-149259). JP, JP-A-58-55450, JP-A-61-22
No. 5151, JP-A-61-233750, JP-A-63-104061, etc.), fluorenylidenemethane derivatives (JP-A-60-69657, JP-A-61-143768, JP-A-61-1
48159) and anthrone derivatives (JP-A-61-225151, JP-A-61-2).
No. 33750) and copper-phthalocyanine.

As a method of forming a thin film of an organic light emitting material, for example, there are a spin coating method, a casting method, an LB method, an evaporation method and the like. The vapor deposition method is preferable because a uniform film is easily obtained and a pinhole is hardly generated. When forming a thin film of a light emitting material by a vapor deposition method, generally,
Boat heating temperature 50-500 ° C, degree of vacuum 10 ^-5 -10 ^-3
Pa, deposition rate 0.01-50 nm / sec, substrate temperature -5
It is desirable to select appropriate conditions within a range of 0 to + 300 ° C. and a thickness of 5 nm to 5 μm. The deposition conditions are selected according to the sublimation temperature of the organic compound used for the light emitting layer, the selection of the state of the thin film to be obtained (for example, microcrystal or amorphous), crystallinity, crystal orientation, and the like.

In the EL device, the electron barrier layer has a role of keeping electrons that are going to the anode side from the light emitting layer in the light emitting layer. By providing an electron barrier layer between the hole injecting and transporting layer and the light emitting layer, preferably in contact with the anode side surface of the light emitting layer, the luminous efficiency of the EL element is improved. The electron barrier layer is preferably a layer having a lower electron mobility than that of the light emitting layer or a layer having an electron affinity smaller than the electron affinity of the light emitting layer.

As a preferred electron barrier layer, a layer composed of a triphenyldiamine-based compound (Applied Physics Letters (Appl. Phys. Lett.), No. 5)
1, p. 913 (1987)), and a layer composed of an aromatic tertiary amine compound (see JP-A-59-194393 and JP-A-63-295695). These act as barriers by not transporting electrons. In addition, the present inventor has proposed that inorganic amorphous material a
-Si _1-X C _X (0.4 <X <1) or a-Si
_A layer consisting of _1-X N _x (0.4 <X <1), wherein the value of X is selected such that the electron affinity of this layer is smaller than the electron affinity of the light-emitting layer, or the range of manufacturing conditions Was found to be suitable for the electron barrier layer. The value of X is more preferably in the range of 0.4 to 0.6. Also in the field of light emitting diodes, values in this range are common. The inorganic amorphous material used for the electron barrier layer need not be a p-type semiconductor.

The electron barrier layer has (1) an ionization energy value between the ionization energy of the hole injection layer and the ionization energy of the light emitting layer, and (2) an ionization energy value larger than that of the light emitting layer. Have two categories. In the (1) type electron barrier layer, the ionization energy increases in the order of anode / hole injection / transport layer / electron barrier layer / light emitting layer, thereby facilitating hole injection. The hole mobility of the electron barrier layer is preferably larger than 10 ⁻⁶ cm ² / V · S. In the (2) type electron barrier layer, holes need to pass through by a tunnel effect, and therefore, the thickness of the electron barrier layer is preferably 20 nm or less.

On the other hand, the hole blocking layer has a role of retaining holes which are going to exit from the light emitting layer to the cathode side in the light emitting layer. Usually, by providing a hole blocking layer so as to be in contact with the cathode side surface of the light emitting layer, the luminous efficiency of the device is improved. The hole barrier layer is preferably a layer whose hole mobility is lower than that of the light emitting layer or a layer whose ionization energy is smaller than that of the light emitting layer. The present inventor has reported that, as a hole barrier layer,
A-Si _1-X C _X (0.4 <
It has been found that an n-type material of X <1) is a preferable material having a small hole mobility. The hole blocking layer made of an inorganic amorphous material has (1) an electron affinity of a value between the electron affinity of the hole injection / transport layer and the electron affinity of the light emitting layer, and (2) a value smaller than that of the light emitting layer. Those having electron affinity are classified into two. (1) type and (2)
Each of the molds has substantially the same effect as described for the electron barrier layer.

The inorganic amorphous thin film can be prepared by a usual method,
For example, plasma CVD, ECR plasma CVD, light C
H by VD etc._Two, SiH_Four, CH_Four, C
_TwoH₆, NH_ThreeCan be prepared from such gases.
For example, a-SiC is H_Two, SiH_FourAnd CH_Four
Can be prepared from A-SiC or a-S
Perform valence electron control and control electric conductivity with i etc.
Usually, B_TwoH₆, PH _ThreeAdd a gas such as a thin film
Is formed, and B, P, etc. are doped in the film. B-doped
In this case, a p-type semiconductor is obtained, and in the case of P-doping, an n-type semiconductor is obtained.

Usually, SiH ₄ , CH ₄ , C ₂ H ₆ , NH
The gas ₃ is used after being diluted to about 10% with hydrogen gas. B ₂ H ₆ and PH ₃ are 500 pp
It is used in a state diluted to about m. These gases are introduced into a CVD furnace by adjusting their mixing ratio, pressure and the like via a mass flow controller. Next, by applying energy such as high frequency, light and electric discharge to decompose the gas in the furnace, a thin film is formed on the substrate. At this time, the substrate is set at an appropriate temperature. The formation rate of the thin film is usually 0.1
It is selected in the range of 10 to 10 nm / min. The formation rate of the thin film is
The choice is made according to the manufacturing method, the type of the raw material, the manufacturing conditions, and the like.

As the anode of the organic EL device according to the present invention, metals, alloys, electrically conductive compounds, and mixtures thereof having a large work function (4 eV or more) are preferably used. Specific examples of the electrode material include metals such as Au, Cu
There are conductive transparent materials such as I, ITO, SnO ₂ and ZnO. The anode can be made by evaporation or sputtering of these electrode materials. When light is extracted from the electrode, it is desirable that the transmittance be greater than 10%. Further, the sheet resistance of the electrode is preferably several hundred Ω / □ or less. The film thickness can be generally 500 nm or less, preferably 10 to 200 nm, depending on the material.

For the cathode, a metal, an alloy, an electrically conductive compound, or a mixture thereof having a small work function (4 eV or less) is used. Specific examples of the cathode material include sodium, sodium - potassium alloy, magnesium, lithium, magnesium / copper mixture, Al / AlO _3, ytterbium, and the like indium. The cathode can be formed by vapor deposition, sputtering, or the like of these substances. The sheet resistance as an electrode is preferably several hundred Ω / □ or less. The film thickness is usually 500 nm or less, preferably 10 nm, depending on the material.
It is selected in the range of -200 nm. In the device of the present invention, it is preferable that one of the anode and the cathode is transparent or translucent in order to allow light to pass therethrough and to efficiently extract the light.

The light emitting layer in the organic EL device of the present invention comprises:
5 thickness of organic compound which has fluorescent property in solid state
It is a thin film of about nm to 5 μm. The light emitting layer has (1) an injection function capable of injecting holes from an anode or a hole injection transport layer and applying electrons from a cathode or an electron injection transport layer when an electric field is applied, and (2) injection function. Transport function to move the electrified (electrons and holes) by the force of the electric field,
(3) It has a light-emitting function of providing a field for recombination of electrons and holes and connecting it to light emission. In the light-emitting layer, there may be a difference between the ease of injecting holes and the ease of injecting electrons, and the transport function represented by the mobility of holes and electrons may be large or small. However, the light-emitting layer preferably transfers either one of the charges.

Regarding the injection function, the ionization energy of the light-emitting layer is preferably 6.0 eV or less, since holes can be relatively easily injected by selecting an appropriate anode material. On the other hand, the electron affinity of the light emitting layer is preferably 2.5 eV or more from the viewpoint that if a proper cathode material is selected, electrons can be relatively easily injected. Further, regarding the light emitting function, it is desirable that the solid state has strong fluorescence. This is because such a light emitting layer has a large ability to convert an excited state such as a compound forming the compound itself, an aggregate of the compound or a crystal into light.

When a DC voltage is applied to the organic EL device of the present invention, the positive polarity is applied to the anode and the negative polarity is applied to the cathode.
When a voltage of about 30 V is applied, light emission is observed from the transparent or translucent electrode layer side. No light emission occurs when a voltage is applied with the opposite polarity. On the other hand, when an AC voltage is applied, light emission occurs only when the anode is in a positive state and the cathode is in a negative state. The waveform of the applied AC voltage may be arbitrary.

Production of EL Devices Examples 1 to 3 EL devices using the hydrazone compound according to the present invention as a hole injecting / transporting material were produced.

A glass substrate (25 mm × 75 mm × 1.1
mm, manufactured by HOYA) was used as a transparent support substrate for the EL element. The substrate was ultrasonically cleaned with isopropyl alcohol for 30 minutes and then dried with dry nitrogen gas. On the dried substrate, a metal mask from which a 2 mm wide stripe was die-cut was placed, and an indium-tin oxide (ITO) film was deposited to a thickness of 1000 ° by sputtering to produce a transparent hole injection electrode. On the glass substrate on which the hole injection electrode was formed, the above compounds 6, 9 and 17 were heated under vacuum,
The thickness was evaporated. Next, bis (2-methyl-8-quinolinol) zinc was heated under vacuum and evaporated to a thickness of 500 ° to form a light emitting layer. Next, magnesium and aluminum were deposited on the light-emitting layer under vacuum at a deposition rate of 10 ° / sec and 1 ° / sec, respectively, for about 1000
A cathode having a thickness of Å was formed. FIG. 1 shows the structure of the organic EL device manufactured by the above process. The organic EL device 10 includes a substrate 1 made of glass, an anode 2 made of ITO, a hole injection / transport layer 3 made of a hydrazone compound of the present invention, a light emitting layer 4, and a cathode 5 made of magnesium and aluminum.

With respect to the three types of EL devices prepared using Compounds 6, 9 and 17, respectively, the emission start applied voltage, the emission color tone, the maximum luminance, and the half-life at 100 cd / m ² were measured. Table 17 shows the obtained results.

[0268]

[Table 17]

Examples 4 to 6 EL devices obtained by adding a charge barrier layer to the EL devices of Examples 1 to 3
Was prepared. There is a charge barrier between the light emitting layer and the hole injection transport layer.
As a wall layer, a thickness of 250Å (25
nm) of an a-SiC film. About other parts
Was similar to each of Examples 1-3. Got
FIG. 2 shows the structure of the EL element. The organic EL element 20 is
Plate 1, anode 2, hole injection / transport layer 3, charge barrier layer 6, light emission
Consists of layer 4 and cathode 5. For the three types of devices obtained
And the emission start applied voltage, emission color tone, maximum brightness, and
100 cd / m^TwoThe half-life at
Was. As a result, the emission color tone and the starting applied voltage change almost
However, the maximum brightness and half-life were 20-30.
% Increase was observed. In particular, Example 1 is an improvement of Example 1
6100 cd / m^TwoExample 5 is an improvement of Example 2
6200 cd / m ^TwoExample 6 is an improved version of Example 3
7100 cd / m^TwoThe highest luminance of each was obtained.

Example 7 In the organic EL device of Example 4, a was used instead of a-SiC.
-Si was formed in a thickness of 50 ° (5 nm) by a vapor deposition method to form an electron barrier layer. As a result, 6300 cd / m ²
Was obtained, which was about 1.5 times that of Example 1.

Examples 8 to 10 EL devices using the hydrazone compound according to the present invention as a light emitting material were prepared.

In the same manner as in Examples 1 to 3, an ITO film was formed on each of the transparent glass substrates. Next, a bisenamine compound represented by the following structural formula was heated under vacuum on the ITO film, and was deposited to a thickness of 700 °.

[0273]

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Next, Compounds 2, 15 and 26 according to the present invention were each heated under vacuum and deposited to a thickness of 500 ° to form a light emitting layer. Next, on the compound film, magnesium and silver were added in an atomic ratio of 10: 1 (Mg: Ag) for 15 minutes.
Co-deposition was performed to a thickness of 00 ° to form a cathode. FIG. 3 shows the structure of the obtained organic EL device. Organic EL element 30
Comprises a substrate 1, an anode 2, a hole injection / transport layer 13 made of a bisenamine compound, a light emitting layer 14 made of a hydrazone compound of the present invention, and a cathode 15 made of magnesium and silver.

With respect to the three types of EL devices prepared using Compounds 2, 15, and 26, respectively, the emission start applied voltage, the emission color tone, the maximum luminance, and the half-life at 100 cd / m ² were measured. Table 18 shows the results.
It can be seen that also when the hydrazone compound of the present invention is used as a light-emitting material, an EL element that emits blue light with high luminance can be obtained.

[0276]

[Table 18]

Example 11 An EL device was prepared by adding an electron injection / transport layer to the device of Example 1. A diphenylquinone derivative represented by the following structural formula was deposited to a thickness of 300 ° between the light emitting layer and the cathode to form an electron injection transport layer.

[0278]

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The other parts were the same as in Example 1. FIG. 4 shows the obtained organic EL device. The EL element 40 includes a substrate 1 made of glass having a thickness of 1.1 mm, an anode 2 made of ITO having a thickness of 1000 °, a hole injection / transport layer 3 having a thickness of 500 ° made of a compound 6 of the present invention, and bis (2-methyl-8).
(Quinolinol) a light emitting layer 4 made of zinc having a thickness of 500 °, an electron injection / transport layer 7 having a thickness of 300 ° made of a diphenylquinone derivative, and a cathode 5 made of a mixed solution of magnesium and aluminum.

In the obtained EL device, the light emission start time, the light emission color tone, the maximum luminance and the half time were measured in the same manner as in Example 1. As a result, the maximum luminance was 6000 cd / m ² , and the maximum luminance was increased by 25% by forming the electron injecting and transporting layer.

Example 12 A device using the hydrazone compound of the present invention as a hole injection / transport material was produced.

A glass substrate provided with a 100-nm-thick ITO transparent electrode (25 mm × 75 mm × 1.1 mm, H
OYA) was used as a transparent support substrate. After the substrate was ultrasonically cleaned with isopropyl alcohol for 30 minutes, it was further immersed and washed in isopropyl alcohol. After the substrate was dried with dry nitrogen gas, it was fixed to a substrate holder of a commercially available vacuum evaporation apparatus.

Each of the three molybdenum resistance heating boats was charged with the hydrazone compound (compound 46)
0 mg, 4,4′-bis (2,
200 mg of 2-diphenylvinyl) biphenyl (hereinafter abbreviated as BDVB) and 200 mg of bis [(2-methyl-8-quinolinolato), (2-naphthrate)] aluminum complex were put in, and they were attached to a vacuum evaporation apparatus. Was.

[0284]

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First, the pressure in the vacuum layer was reduced to 4 × 10 ⁻⁴ Pa, and then the heating boat containing the compound 46 was energized to supply 280
Heated to ° C. Compound 46 was vapor-deposited on the substrate at a vapor deposition rate of 0.1 to 0.3 nm / sec to provide a 60-nm thick hole injection / transport layer. Next, the heating boat containing BDVB was energized and heated to 240 ° C. Deposition rate 0.1-0.3
BDVB was deposited on the hole injecting and transporting layer at a rate of nm / sec to provide a 40 nm thick light emitting layer. Further, the heating boat containing the aluminum complex was energized and heated to 314 ° C.
An aluminum complex was vapor-deposited on the light emitting layer at a vapor deposition rate of 0.1 nm / sec to form an electron injection transport layer having a thickness of 20 nm.
In addition, the substrate temperature at the time of vapor deposition was room temperature. Next, the vacuum layer was opened, and a stainless steel mask was placed on the electron injection transport layer. 3 g of magnesium was placed in a molybdenum resistance heating boat, and 0.5 g of silver was placed in a tungsten evaporation basket. After the pressure in the vacuum chamber was again reduced to 2 × 10 ⁻⁴ Pa, the boat containing magnesium was energized to deposit magnesium at a deposition rate of 1.5 to 2.0 nm / sec. At the same time, the silver basket was heated to deposit silver at a deposition rate of 0.1 nm / sec. A counter electrode made of a mixture of magnesium and silver was formed to complete an organic EL device. FIG. 5 shows the structure of the obtained device. EL element 50
Are a glass substrate 51, an ITO transparent electrode 52, a compound 46
, A light-emitting layer, an electron injection-transport layer 57, and a cathode 55.

The ITO electrode of the obtained device was used as an anode, and a counter electrode made of a mixture of magnesium and silver was used as a cathode.
When a DC voltage of 1 V was applied, the current density was 5.8 mA.
/ Cm ² flows and develops blue color (chromaticity coordinates: 0.1
8, 0.20). The maximum wavelength of this emission is 46
8 nm, luminance was 84 cd / m ² , and luminous efficiency was 0.41 lumen / W. Even after 100 hours from the energization under an argon gas flow, there was no peeling or clouding of the electrode surface, and blue light emission was still observed.

Examples 13 to 18 The same procedures as in Example 12 were carried out except that the hole injecting / transporting layer was formed using the compounds shown in Table 19 instead of the compound 46, and the heating temperature during the deposition was changed as shown in Table 19. A device was prepared and evaluated. Table 19 shows the obtained results.

[0288]

[Table 19]

Example 19 An element using the hydrazone compound of the present invention as a light emitting material was produced.

A light emitting layer was formed by using the compound 46 of the present invention in place of BDVB, a bisenamine compound represented by the following structural formula was used as a material for the hole injecting and transporting layer, and the heating boat temperature during the deposition was 285 A device was prepared and evaluated in the same manner as in Example 12 except that the temperature was changed to 300C and 300C.

[0291]

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In the obtained device, when a DC voltage of 12.5 V was applied using an ITO electrode as an anode and a counter electrode made of a mixture of magnesium and silver as a cathode, a current density of 11.6 mA / cm ² flowed. And green light emission (chromaticity coordinates: X = 0.253, Y = 0.467) was obtained. The maximum wavelength of this light emission is 513 nm and the luminance is 110
cd / m ² , and the luminous efficiency was 0.24 lumen / W. Even after 200 hours from the energization under an argon gas flow, no peeling or turbidity of the electrode surface was observed, and green light emission with a luminance of 55 cd / m ² continued.

Example 20 A device was prepared and evaluated in the same manner as in Example 19, except that Compound 63 was used as the material for the light emitting layer, and the temperature of the heating boat during vapor deposition was changed to 314 ° C. Anode for ITO electrode,
When a DC voltage of 11 V was applied using a counter electrode made of a mixture of magnesium and silver as a cathode, the current density was 7.
Current flowed at 1 mA / cm ² , and green light emission was obtained.
The maximum wavelength of this light emission is 507 nm, and the luminance is 100 cd /
m ² , and the luminous efficiency was 0.4 lumen / W. Even after 200 hours from the energization under an argon gas flow, there was no peeling or clouding of the electrode surface, and green light emission with a luminance of 50 cd / m ^{2 was} still maintained.

Example 21 A device was produced using the hydrazone compound of the present invention as a hole injecting and transporting material.

The transparent support substrate prepared in Example 12 was used.
Compound 46 of the present invention and BDVB were placed in different molybdenum resistance heating boats, and they were attached to a vacuum evaporation apparatus. In the same manner as in Example 12, a hole injection / transport layer made of Compound 46 was formed on the ITO transparent electrode, and a BDVB layer was further formed thereon. Next, a counter electrode made of a mixture of magnesium and silver was laminated to obtain a two-layer EL element. The thicknesses of the hole injection transport layer and the BDVB light emitting layer were 40 nm and 35 nm, respectively. The emission luminance of the obtained EL device was 60 cd / m ² . This value is
, But no significant decrease was observed for the other properties.

Example 22 A device was prepared using the hydrazone compound of the present invention as a hole injection / transport material and provided with an electron barrier layer.

A device was prepared by adding an electron barrier layer to the EL device of Example 12. As an electron barrier layer, a 10 nm-thick pa-SiC layer was formed between the hole injection / transport layer and the light emitting layer. This layer was prepared by RF plasma CVD. SiH ₄ and CH ₄ are each 10% with hydrogen gas
And B ₂ H ₄ was further diluted to 5000 ppm with hydrogen. The diluted source gas and doping gas were respectively introduced into the chamber via a mass flow controller, and p-a-SiC was deposited with an RF plasma output of 40 W. The other parts were formed in the same manner as in Example 12. FIG. 6 shows the structure of the obtained EL element. The organic EL element 60 includes a glass substrate 51, an ITO electrode 52, a hole injection / transport layer 53,
It includes an electron barrier layer 68, a light emitting layer 54, an electron injection / transport layer 57, and a cathode 55.

The characteristics of the obtained EL device were measured in the same manner as in Example 12. When a DC voltage of 11 V was applied, the current density was 5.3 mA / cm ² , and blue color was obtained. The maximum wavelength of this light emission is 516 nm, and the luminance is 890.
cd / m ² and the luminous efficiency were 1.6 lumen / W.
As a result, the electron barrier layer has improved brightness and efficiency.

[0299]

The novel hydrazone derivative according to the present invention exhibits excellent properties as a hole injecting / transporting material or a light emitting material for an EL device. By using the compound of the present invention, it is possible to provide an organic EL device having excellent adhesion between an electrode and a film, exhibiting high luminance and high luminous efficiency, and having a long lifetime. In addition, the compound of the present invention can be suitably used as a photoconductive material, a waveguide material, and the like by utilizing the above-mentioned properties as an electronic material.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing a structure of an element prepared in Production Examples 1 to 3 of an EL element.

FIG. 2 is a schematic cross-sectional view showing a structure of an element manufactured in Production Examples 4 to 6 of an EL element.

FIG. 3 is a schematic cross-sectional view showing a structure of an element prepared in Production Examples 8 to 10 of an EL element.

FIG. 4 is a schematic sectional view showing the structure of an element prepared in Production Example 11 of an EL element.

FIG. 5 is a schematic sectional view showing the structure of an element prepared in Production Example 12 of an EL element.

FIG. 6 is a schematic sectional view showing the structure of an element prepared in Production Example 22 of an EL element.

[Explanation of symbols]

 1, 51 Substrate 2, 52 Anode 3, 13, 53 Hole Injection / Transport Layer 4, 14, 54 Emitting Layer 5, 15, 55 Cathode 6 Charge Barrier Layer 7, 57 Electron Injection / Transport Layer 10, 20, 30, 40, 50, 60 Organic EL device 66 Electron barrier layer

Claims (14)

[Claims] (1) Formula (1) (Wherein Q represents — (CH ₂ ) _m — or a substituted or unsubstituted arylene group, m represents an integer of 0 to 4, and R ¹ and R ² each represent a hydrogen atom, an alkyl group or a substituted or unsubstituted R ³ and R ⁴ each represent an alkyl group or a substituted or unsubstituted aryl group; R ⁵ represents a substituted or unsubstituted aryl group;
⁶ represents a substituted or unsubstituted aryl group, an alkyl group or a hydrogen atom), and is a hydrazone derivative containing two enamine groups. 2. The formula: (Wherein, R ³ , R ⁴ and R ⁶ are as defined above, R ³ and R ⁴ are the same, and R ⁷ represents a halogen atom, a lower alkoxy group, a lower alkyl group or a hydrogen atom, And n is an integer of 1 to 3). 3. The formula: (Wherein, Q, R ¹ , R ² , R ³ and R ⁴ are as defined above, and R ⁸ and R ⁹ each represent a hydrogen atom, a lower alkyl group or a substituted or unsubstituted aryl group, or R ⁸ and R ⁹ together with the two carbon atoms of the cycloalkane form part of a substituted or unsubstituted aromatic hydrocarbon, and r represents an integer from 3 to 6)
A hydrazone derivative containing two enamine groups. 4. The formula: Wherein R ¹ , R ² , R ³ and R ⁴ are as defined above, R ¹ and R ² are the same, R ³ and R ⁴ are the same, and R ¹⁰ is hydrogen The hydrazone derivative according to claim 3, which represents an atom, a lower alkyl group, a lower alkoxy group or a halogen atom, and s represents an integer of 1 to 3). 5. A compound of the formula (Wherein, R ¹ , R ² , R ³ , R ⁴ and s are as defined above, R ¹ and R ² are the same, R ³ and R ⁴ are the same, and X is Oxygen atom, sulfur atom or Wherein R ¹³ represents a hydrogen atom or a lower alkyl group and t represents 0 or 1, and R ¹¹ and R ¹² each represent a hydrogen atom, a halogen atom, a lower alkyl group or a lower alkoxy group. 2. A hydrazone derivative containing two enamine groups. 6. The formula: Wherein R ¹ , R ² , R ³ , R ⁴ and s are as defined above, R ¹ and R ² are the same, and R ³ and R ⁴ are the same. The hydrazone derivative according to claim 5, which is represented. 7. A hole injection / transport material for an electroluminescent element, comprising the hydrazone derivative according to claim 1. Description: 8. A luminescent material for an electroluminescent device, comprising the hydrazone derivative according to claim 1. Description: 9. An electroluminescent device in which an anode, a hole injecting and transporting layer, a light emitting layer, and a cathode are sequentially stacked, wherein the hole injecting and transporting layer comprises the hydrazone derivative according to any one of claims 1 to 6. An electroluminescent device, comprising: 10. An electroluminescent device in which an anode, a hole injecting and transporting layer, a light emitting layer, an electron transporting layer, and a cathode are sequentially laminated, wherein the hole injecting and transporting layer is any one of claims 1 to 6. An electroluminescent device comprising a hydrazone derivative of the formula (1). 11. An electroluminescent device in which an anode, a hole injecting and transporting layer, a light emitting layer and a cathode are sequentially stacked, wherein the light emitting layer contains the hydrazone derivative according to any one of claims 1 to 6. An electroluminescent element characterized by the above-mentioned. 12. An electroluminescent device in which an anode, a hole injecting and transporting layer, a light emitting layer, an electron transporting layer, and a cathode are sequentially laminated, wherein the light emitting layer is a hydrazone derivative according to any one of claims 1 to 6. An electroluminescent device comprising: 13. The electroluminescent device according to claim 9, further comprising a charge barrier layer between said anode and said cathode. 14. The electroluminescent device according to claim 13, wherein the charge barrier layer is an electron barrier layer.