JPH0517765A - Organic electroluminescence element - Google Patents

Abstract

PURPOSE:To obtain an organic electroluminescence element having high brightness regardless of low voltage and having practical emitting efficiency and blue based emission by using a specific compound as a luminous material. CONSTITUTION:The objective element using a compound expressed by formula I (X and Z are formula II, formula III, etc.; Y is formula IV, formula V, etc.) as a luminous material and simultaneously having >=0.8 lumen/W emitting efficiency. Preferably, the element has a laminated structure in the order of anode/ positive hole injecting layer/luminescent layer/electron-injecting layer/cathode on a supporting sheet. Furthermore, a compound expressed by formula I is preferably obtained by subjecting a mixed solution obtained by dissolving an ester phosphonate and an aldehyde in a solvent such as ethanol to Witting- Horner reaction in the presence of a base such as NaH.

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 an organic electroluminescence device capable of emitting blue light at low voltage, high brightness and high efficiency.

[0002]

2. Description of the Related Art Electroluminescent devices (hereinafter referred to as EL devices) have the characteristics that they are self-luminous and have high visibility, and because they are completely solid devices, they are excellent in impact resistance. At present, various EL elements using inorganic or organic compounds in the light emitting layer have been proposed and are being put into practical use. Of these, organic thin film E
Since the applied voltage of the L element can be greatly reduced, various materials are being developed. For example, JP-A-59
Japanese Patent Laid-Open No. 194393 discloses an organic thin film EL element that exhibits high brightness when a low voltage of 25 V or less is applied. This organic EL element is a laminated type of anode / hole injection layer / light emitting layer / cathode, but it is necessary that the film thickness between electrodes is 1 μm or less, and therefore it is used for the light emitting layer. Depending on the compound, there is a problem that pinholes are likely to occur and the productivity is low, and in the examples using tetraphenylbutadiene for the light emitting layer, the luminous efficiency in blue light emission is extremely low. Also, European Patent Publication 028138
According to Japanese Patent Laid-Open No. 1, an anode / hole injection / transport zone / emission zone /
A laminated type cathode is disclosed. Here, the emission band is composed of a thin film composed of a host material and a trace amount of fluorescent material in the host material. However, the E disclosed here
With respect to light emission in the green to red region, the L element can achieve high output by applying a low voltage, but cannot achieve blue light emission.

Further, US Pat. Nos. 4,672,265, 4,725,513 and 4,734,338.
No. 474,1976, No. 4775
No. 820, JP-A-61-37890, and the like disclose a two-layer stack of a light emitting layer made of an electron-accepting electroluminescent compound and a light emitting layer made of an electron-donating electroluminescent compound. An organic EL device having a laminated structure including a basic structure is disclosed. Here, the electroluminescent compound is a compound that has high emission quantum efficiency, has a π-electron system that is susceptible to external perturbation, and can be electrically excited. However, in these, it is essential that the light emitting layer has two layers, and various interactions represented by the formation of an exciplex of an electron donating compound and an accepting compound forming the two layers near the interface between the two layers are essential. Since the light emission is caused by the light emission, and the light emission performance greatly depends on the state of the interface, the manufacturing conditions are difficult, and the light emission significantly decreases due to the deterioration of the interface.

In the organic EL devices disclosed in US Pat. Nos. 4,672,265 and 4,725,513, at least one of the two light emitting layers is a molecular cumulative film by the LB method. The long-chain alkyl chain used has a heat-resistant temperature of about 100 ° C. and is weak to heat (Journal of Polymer Science, 36,267 (1987)). Therefore, when the counter electrode is vapor-deposited, the above-mentioned molecular cumulative film or the like is damaged and the yield of the device becomes poor. An important drawback to this is that long-chain alkyl chains generally have significantly low mobility, which significantly dissipates charge mobility, which makes the device unsatisfactory in luminous performance and impractical. . U.S. Pat. No. 4,734,338, No. 4741
Nos. 976 and 4775820 disclose a two-layer structure of a light emitting layer having an insulating layer added, but the light emitting performance is not sufficient because charge mobility is similarly excluded. , Lacks in practicality. Incidentally, as a light emitting layer using a distyrylbenzene derivative alone, Japanese Patent Application No.
No. 63-308859. The organic EL device shown here is of a single layer type having only a light emitting layer, and although the emission intensity and the light emitting efficiency are good as a single layer type, there is still room for improvement in practical use.

European Patent Publication No. 0373582
In JP-A No. 2004-242, by using a light-emitting material that is a novel distyrylbenzene derivative, a high-luminance organic EL device that emits blue light is obtained, but it has not been possible to obtain a practical light-emission efficiency. Low voltage, high brightness and high efficiency organic E
L element has been reported (The 51st Japan Society of Applied Physics, Academic Lecture, Proceedings 1204 pages, JSAP, Co, No. AP901125-0
0 and the same announcement), but it has not yet reached the practical luminous efficiency (more than 0.8 lumen / W).

[0006]

SUMMARY OF THE INVENTION Therefore, the present inventors have solved the above-mentioned drawbacks of the prior art, have a high luminance despite a low voltage, and have a practical luminous efficiency (0.8 lumen / W or more). ) Was obtained, and further, earnest research was repeated to develop an organic EL device that emits blue light. As a result, they have found that by using a light emitting material having a specific structure, the light emission efficiency can be remarkably improved and the above object can be sufficiently achieved. The present invention has been completed based on such findings. That is, the present invention has the general formula (I)

[0007]

[Chemical 4]

(In the formula, X and Z are independently

[0009]

[Chemical 5]

And Y is

[0011]

[Chemical 6]

Is shown. The present invention provides an organic electroluminescence device characterized by using a luminescent material represented by the formula (1) and having a luminous efficiency of 0.8 lumen / W or more. Further, the present invention includes (1) anode / light emitting layer / electron injection layer / cathode, (2) anode / hole injection layer / light emitting layer / electron injection layer / cathode, (3) anode / hole injection layer / light emitting layer / The present invention also provides an organic electroluminescence device using the above light emitting material, which is formed by stacking a cathode or (4) anode / light emitting layer / cathode in this order.

In the present invention, the compound used as the light emitting material is a compound represented by the above general formula (I). Here, each symbol in the formula is as described above. There are various compounds represented by the general formula (I).

[0014]

[Chemical 7]

[0015]

[Chemical 8]

[0016]

[Chemical 9]

[0017]

[Chemical 10]

[0018]

[Chemical 11]

And the like. The compound represented by the general formula (I) is a mixed solution of phosphonate ester and aldehyde (solvent: ethanol, benzene, tetrahydrofuran (THF), N, N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO).
Etc.) in the presence of a base (NaH, NaNH ₂ , ROM (R: alkyl group, M: Li, Na, K)) to give a high yield of olefin, which is easily synthesized by the Wittig-Horner reaction. Can (Horner L ,; Hoffmann H .;
Wippel HG; Chem. Ber., (1959) 92, 2499).

In the organic EL device of the present invention, the compound of the general formula (I) is used as a light emitting material, and at the same time, it is preferable to have a laminated structure with a hole injection layer and / or an electron injection layer. With such a laminated structure, the emission intensity can be significantly improved as compared with a single layer type having only a light emitting layer. The laminated structure in the organic EL device of the present invention has the following structure: (1) Anode / light emitting layer / electron injection layer / cathode in order, (2) Anode / hole injection layer / light emitting layer / electron injection layer / cathode in order, (3) Anode / hole injecting layer / light emitting layer / cathode are laminated in this order or (4) Anode / light emitting layer / cathode are laminated in this order. Note that these EL elements are preferably formed on a supporting substrate.

The light emitting layer in the organic EL device of the present invention is
It has the following two functions. That is, a. Injection transport function When an electric field is applied, holes can be injected from the anode or the hole injection layer, electrons can be injected from the cathode or the electron injection layer, and the injected charges (electrons and holes) Function to move by force b. Light-emitting function Function to provide a field for recombination of electrons and holes and connect it to light emission. However, there may be a difference between the ease with which holes are injected and the ease with which electrons are injected. Although the transport capacity represented by the mobility may be large or small, it is preferable to transfer either one of the charges. In the organic EL device of the present invention, the compound of the general formula (I) used as the light emitting material (light emitting layer) preferably has an ionization energy.
It is 6.0 eV or less, and it is relatively easy to inject holes if an appropriate anode metal or anode compound is selected. Further, the electron affinity is preferably 2.5 eV or more, and if a suitable cathode metal or cathode compound is selected, it is relatively easy to inject electrons, and the positive hole mobility is superior to the electron mobility. It is a luminescent material having a hole transporting property. Furthermore, since the solid-state fluorescence is strong, the compound has a large ability to convert the excited state of the above-mentioned compound formed at the time of recombination, its associated body, crystal or the like into light.

The substrate that can be used in the organic EL device of the present invention is preferably one having transparency, and generally glass, transparent plastic, quartz or the like is used. Further, as the electrodes (anode, cathode), metals, alloys, mixtures or indium tin oxide (a mixed oxide of indium oxide and tin oxide; I
It is preferable to use transparent materials such as TO), SnO _{2 and} ZnO. A metal or an electrically conductive compound having a large work function is suitable for the anode, and a metal or an electrically conductive compound having a small work function is suitable for the cathode. At least one of these electrodes is preferably transparent or semi-transparent.

In the organic EL device of the present invention, the hole injecting layer and the electron injecting layer may be omitted, but those having both layers are more preferable and the light emitting performance is further improved. Here, the hole injection layer is made of a hole transfer compound and has a function of transferring holes injected from the anode to the light emitting layer. By sandwiching this layer between the anode of the EL device and the light emitting layer, more holes are injected into the light emitting layer at a low voltage, and the brightness of the device is improved. The hole-transporting compound of the hole-injection layer used here is disposed between two electrodes provided with an electric field to facilitate injection of holes from the anode, and at the same time, the holes are appropriately introduced into the light-emitting layer. It is a compound that can be transmitted. 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-transporting compounds here are at least 10 ⁻⁶ when the layer is arranged between electrodes which are provided with an electric field of 10 ⁴ to 10 ⁶ volts / cm.
It has a hole mobility of cm ² / volt · second. Therefore, preferable examples include various compounds used as hole transport compounds in photoconductive materials.

Examples of such a hole transfer compound include the following. Triazole derivatives described in U.S. Pat. No. 3,121,197, oxadiazole derivatives described in U.S. Pat. No. 3,189,447, etc., imidazole derivatives described in Japanese Patent Publication No. 37-16096, etc., US Patent No. 36154
No. 02, No. 3820989, No. 3542544, Japanese Patent Publication Nos. 45-555, 51-10983, and JP-A Nos. 51-93224 and 55-1710.
No. 5, No. 56-4148, No. 55-108667,
Polyarylalkane derivatives described in JP-A-55-156953 and JP-A-56-36656, US Pat. Nos. 3,180,729 and 4,278,746, and JP-A-55-88064, 55-88065, and JP-A-55-88065. Four
9-105537, 55-51086, 56-
No. 80051, No. 56-88141, No. 57-455.
No. 45, No. 54-112637, No. 55-74546.
Pyrazoline derivatives and pyrazolone derivatives described in Japanese Patent Publication No. 3615404 and Japanese Patent Publication Nos. 51-10105, 46-3712 and 47.
No. 25336 and Japanese Patent Laid-Open No. 54-53435.
Nos. 54-110536, 54-119925, and the like, phenylenediamine derivatives, and US Pat. Nos. 3,567,450, 3,180,703 and 3,
240597, 3658520, and 423210.
No. 3, No. 4175961, No. 4012376, Japanese Patent Publication No. 49-35702, No. 39-27577, and JP-A Nos. 55-144250 and 56-11.
No. 9132, No. 56-22437, West German Patent No. 1
Arylamine derivatives described in 110518, etc., amino-substituted chalcone derivatives described in US Pat. No. 3,526,501, US Pat. No. 32
57203 and the like, styrylanthracene derivatives described in JP-A-56-46234 and JP-A-54-1108.
Fluorenone derivatives described in JP-A-37-37, U.S. Pat. No. 3,717,462 and JP-A-54-591.
No. 43, No. 55-52063, No. 55-52064
No. 55-46760, No. 55-85495, No. 57-11350, No. 57-148749, and other hydrazone derivatives described in JP-A No. 61-210.
No. 363, No. 61-228451, No. 61-1464
2, No. 61-72255, No. 62-47646,
62-36674, 62-10652, 62.
-30255, 60-93445, 60-94
No. 462, No. 60-174749, No. 60-1750.
The stilbene derivatives described in Japanese Patent No. 52, etc. can be enumerated.

A particularly preferred example is JP-A-63-2.
Examples thereof include a compound (aromatic tertiary amine) as a hole transport layer and a compound (porphyrin compound) as a hole injection zone, which are disclosed in Japanese Patent Publication No. 95695. Further, a particularly preferable example of the hole transfer compound is disclosed in JP-A-Sho 5
No. 3-27033, No. 54-58445, No. 54-149634, No. 54-64299, No. 55-79450, No. 55-144250.
No. 56-119132, No. 61-295.
No. 558, No. 61-98353, US Pat. No. 4,127,412, and the like. The examples are as follows.

[0026]

[Chemical 12]

[0027]

[Chemical 13]

[0028]

[Chemical 14]

[0029]

[Chemical 15]

A hole injection layer is formed from these hole transfer compounds, but the hole injection layer may be composed of one layer,
Alternatively, a hole injecting and transporting layer using a compound different from the above layer may be laminated.

On the other hand, the electron injection layer is made of a compound that transmits electrons. Preferred examples of the electron transfer compound forming the electron injection layer include:

[0032]

[Chemical 16]

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

[0034]

[Chemical 17]

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

[0036]

[Chemical 18]

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

[0038]

[Chemical 19]

A compound represented by the formula: 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 anthraquinodimethane derivatives and anthrone derivatives described in JP-A No. 0-publication. In addition, the following general formulas (II) and (III)

[0040]

[Chemical 20]

(In the formula, Ar ^{1 to} Ar ³ and Ar ⁵ each independently represent an aryl group, and Ar ⁴ represents an arylene group. These aryl groups and arylene groups may or may not be substituted. May be used). Here, examples of the aryl group include a phenyl group, naphthyl group, biphenyl group, anthranyl group, perylenyl group, pyrenyl group, and the like, and examples of the arylene group include a phenylene group, a naphthylene group, a biphenylene group, an anthracenylene group, a perylenylene group, Examples thereof include a pyrenylene group. Moreover, as a substituent, a C1-C10 alkyl group, a C1-C10 alkoxy group, a cyano group, etc. are mentioned. The compounds represented by the general formulas (II) and (III) are preferably those capable of forming a thin film. Specific examples of the compounds represented by the general formulas (II) and (III) include:

[0042]

[Chemical 21]

[0043]

[Chemical formula 22]

[0044]

[Chemical formula 23]

And the like. In order to produce the organic EL device having the above-mentioned configuration (1) anode / light emitting layer / electron injection layer / cathode, for example, the following procedure may be followed. 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, particularly 200 nm or less is preferable in order to increase the transmittance of light emission. Next, a light emitting material is formed in a thin film on this electrode to form a light emitting 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 a vapor deposition method is adopted for thinning, the vapor deposition conditions are, for example, boat heating temperature of 50 to 400 ° C., vacuum degree of 10 ⁻⁵ to 10 ⁻³ Pa, vapor deposition rate.
The film thickness may be selected to be 5 nm to 5 μm in the range of 0.01 to 50 nm / sec and the substrate temperature of −50 to + 300 ° C. The above-mentioned conditions differ depending on the type of compound and the intended crystal structure, association structure, etc. of the molecular deposited film, and cannot be uniquely determined, but the heating temperature of the boat can be limited to a temperature at which the compound does not decompose. preferable. After forming the light emitting layer, an electron injection 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 light emitting layer. After that, the counter electrode is formed with a film thickness of 50 to 20 by a vapor deposition method or a sputtering method.
If it is formed with a thickness of 0 nm, the target organic EL element is created.

(2) Anode / hole injection layer / light emitting layer /
In order to prepare an EL device having an electron injection layer / cathode structure, first, an electrode, a hole injecting and transporting layer, and a light emitting layer are formed on the organic E of the above (1).
The electron injection material (electron transfer compound) is formed into a thin film by the vapor deposition method to form an electron injection transport layer on the light emitting layer, and finally, the organic EL device of the above (1) is formed. Similar to the case of forming the element, by forming the counter electrode, the intended organic EL element having the above-mentioned configuration (2) is formed. 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.

Furthermore, (3) In order to prepare an organic EL element having a structure of anode / hole injection layer / light emitting layer / cathode, electron injection is carried out when the organic EL element of the above-mentioned structure (2) is prepared. The formation of layers may be omitted.

(4) Organic E having a constitution of anode / light emitting layer / cathode
To create an L element, the organic EL having the above-mentioned configuration (2) is used.
The formation of the hole injection layer and the electron injection layer may be omitted when the device is formed. In addition, a hole injection layer between the pair of electrodes,
Anode sandwiching a mixture of a light emitting layer and an electron injection layer /
In the case of an element composed of a light emitting layer / cathode,
For example, a thin film made of a substance for an anode 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 to the thin film, or from this solution. There is one in which a thin film is formed by a dip coating method to form a light emitting layer, and 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 produced light emitting layer, and a thin film made of a substance for a cathode may be formed thereon.

The 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.

[0050]

EXAMPLES The present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples. Synthesis example 1

[0051]

[Chemical formula 24]

1.8 g of a phosphonate represented by the following formula was 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-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 8.5 (m, 26H: H of central biphenylene ring and carbazole ring) δ (ppm) = 4.3 (q, 4H: methylene ethyl group _{(-CH 2 -)) δ (} ppm) = 1.4 (t, 6H: methyl ethyl (-
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

[0054]

[Chemical 25]

It was confirmed that

Synthetic Examples 2 to 11 The same reaction as in Synthetic Example 1 was carried out except that the phosphonate ester, aldehyde, solvent and base shown in Table 1 were used.

[0057]

[Table 1]

[0058]

[Table 2]

[0059]

[Table 3]

[0060]

[Table 4]

Example 1 ITO on a 25 mm x 75 mm x 1.1 mm glass substrate
A film formed by vapor deposition to a thickness of 100 nm (HOY
A) was used as a transparent support substrate. Then, this transparent support group
Plate is propyl alcohol, pure water, isopropyl alcohol
Ultrasonic cleaning in order, and then blow dry nitrogen.
The solvent was removed from the surface of the dipped substrate. Furthermore, this transparent branch
Holding substrate UV / O₃Dry stripper (Samco Inter
(Made by National) for 10 minutes to remove the organic substances on the substrate surface.
Removed. A commercially available vapor deposition device (Japan
Made in molybden by fixing to a substrate holder of Sky Technology Co., Ltd.
The compound 1 (DP
200 mg of ABi) and another molybdenum bow
TBu-PBD (manufactured by Dojin Chemical Co., Ltd.) in 200 mg
1 x 10 vacuum chamber^-FourThe pressure was reduced to Pa. Then D
The boat containing PABi is heated to deposit DPABi
Deposition on a transparent support substrate at a speed of 0.1 to 0.3 nm / sec,
A light emitting layer having a film thickness of 60 nm was formed. Substrate temperature at this time
Was at room temperature. Then remove it from the vacuum chamber.
Without heating the other boat on the luminescent layer
By using tBu-PBD as an electron injection layer with a thickness of 20 nm
It was vapor-deposited. Vapor deposition rate at this time is 0.2-0.4 nm / sec.
The plate temperature was room temperature. Take the resulting stack from the vacuum chamber
Out, install a stainless steel mask, and
It was fixed to the plate holder. Next, a resistance heating switch made of molybden
Put 1g of Magnesium ribbon in the box and add another tongue
A resistance heating filament made of stainless steel is loaded with 500 mg of Ag.
I wore it. Then, the vacuum chamber is set to 2 x 10^-FourDecompress to Pa,
The deposition rate of Ag is 0.07 to 0.09 nm / sec.
Deposition rate of magnesium from one boat is 1.5-2.0 nm
It vapor-deposited at the rate of / sec. In this way, magnesium and Ag
The mixed metal electrode of 150 nm is laminated and vapor-deposited on the light emitting layer to face it.
It was used as an electrode. This mixed metal electrode is the anode and the ITO electrode is the shadow.
As a result of applying 6 V DC as a pole, the current is 56 mA / cm
²A uniform light of blue-green color was obtained. The result of the spectroscopic measurement,
Maximum wavelength is 478 nm, emission brightness is 1260 cd /
m², Luminous efficiency was 1.2 lumen / W. Also, this
Element is stable at 3100 cd / d when DC 10V is applied.
m ²The brightness of

Example 2 An organic EL device was prepared and evaluated in the same manner as in Example 1 except that the compound 8 obtained in Synthesis Example 1 was used as the light emitting material. When a direct current of 6 V was applied to the obtained organic EL device, a current flowed at 16.4 mA / cm ² and blue-green uniform light was obtained. As a result of the spectroscopic measurement, the emission luminance is 560 cd /
m ² , and the luminous efficiency was 1.8 lumen / W. In addition, when a direct current of 7 V was applied, a current of 61 mA / cm ² flowed through this element, and a stable luminance of 2000 cd / m ² was obtained. Luminous efficiency was 1.5 lumen / W

Example 3 An organic EL device was prepared in the same manner as in Example 1 except that the compound 8 obtained in Synthesis Example 1 was used as the luminescent material and no electron injection layer was prepared. It was As a result of applying DC 5V to the obtained organic EL device, the current was 10.8 mA.
/ Cm ² flow and a uniform light of blue-green color was obtained. As a result of the spectroscopic measurement, the light emission luminance was 102 cd / m ² , and the light emission efficiency was 0.8 lumen / W.

Examples 4 to 12 Compound 2 obtained in Synthesis Example 3 (Example 4), compound 3 obtained in Synthesis Example 4 (Example 5), compounds obtained in Synthesis Example 5 as luminescent materials 4 (Example 6), compound 5 obtained in Synthesis Example 6 (Example 7), compound 6 obtained in Synthesis Example 7 (Example 8), compound 7 obtained in Synthesis Example 8 (Example 9) ), Compound 9 obtained in Synthesis Example 9 (Example 10), compound 10 obtained in Synthesis Example 10 (Example 11) or compound 11 obtained in Synthesis Example 11 (Example 12) was used. An organic EL element was produced in the same manner as in Example 1 except for the above. The results of the evaluation test are shown in Table 2.

[0065]

[Table 5]

Comparative Examples 1 to 3 Organic EL devices were prepared in the same manner as in Examples except that the light emitting materials shown in Table 3 were used. The results of the evaluation test are shown in Table 3.

[0067]

[Table 6]

[0068]

[Table 7]

[0069]

As described above, the organic EL device of the present invention can obtain high brightness by simply applying a low voltage and has a very high luminous efficiency. In addition, this device enables blue light emission, which was conventionally difficult, with high brightness and high efficiency. Therefore, the organic EL device of the present invention can be used as a display device for various devices, a display device such as a light emitting device.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tadashi Kusumoto             1280 Kamizumi, Sodegaura, Chiba Prefecture Idemitsu Kosan Co., Ltd.             Inside the company

Claims (4)

[Claims] 1. A compound represented by the general formula (I): (In the formula, X and Z are independently Is shown, and Y is Indicates. ). An organic electroluminescence device characterized by using a luminescent material represented by the formula (1) and having a luminous efficiency of 0.8 lumen / W or more. 2. The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is formed by laminating an anode / a light emitting layer / an electron injection layer / a cathode in this order. 3. The organic electroluminescence device according to claim 1, wherein the organic electroluminescence device is formed by laminating in the order of anode / hole injection layer / light emitting layer / electron injection layer / cathode. 4. The organic electroluminescence device according to claim 1, which is formed by laminating an anode / a light emitting layer / a cathode in this order.