JP2003064355A - Organic electroluminescent element and full-color display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having an improved emission luminance and a display device having a low power consumption and a high luminance using the organic electroluminescent element. SOLUTION: This organic electroluminescent element has a light-emitting layer containing both a fluorescent compound and a phosphorescent compound. The organic electroluminescent element is characterized in that the ratio (N/C) of the number of nitrogen atoms to the number of carbon atoms in the molecule of the fluorescent compound is >=0 and <=0.05 and the emission maximum wavelength obtained by the electroluminescence in a state of the fluorescent compound converted into the element is a longer wavelength than the fluorescence maximum wavelength of the fluorescent compound.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic electroluminescence (hereinafter abbreviated as organic EL) element and a display device. More specifically, the present invention relates to an organic electroluminescence device having excellent emission brightness,
And a display device having the organic electroluminescence element.

[0002]

2. Description of the Related Art An electroluminescent display (ELD) is used as a light emitting type electronic display device.
There is. Examples of the ELD constituent elements include an inorganic electroluminescent element and an organic electroluminescent element. Inorganic electroluminescent elements have been used as a flat light source, but a high alternating voltage is required to drive the light emitting element. An organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and electrons and holes are injected into the light emitting layer to recombine to generate excitons (excitons). It is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when the excitons are generated and deactivated, and can emit light at a voltage of several V to several tens of V. Further, it is a self-luminous type. Therefore, it has a wide viewing angle and high visibility, and since it is a thin-film type complete solid-state element, it is attracting attention from the viewpoints of space saving, portability, and the like.

However, in the organic EL element for practical use in the future, it is desired to develop an organic EL element which emits light with high efficiency and low power consumption.

The full color system of the organic EL device of the present invention is characterized by using a fluorescent light emitting material as a host compound and a phosphorescent compound as a dopant.

In Japanese Patent No. 3093796, a stilbene derivative, a distyrylarylene derivative or a trisstyrylarylene derivative is doped with a small amount of a phosphor to improve the emission brightness and prolong the life of the device.

Further, a device having an organic light-emitting layer in which an 8-hydroxyquinoline aluminum complex is used as a host compound and a slight amount of phosphor is doped therein (Japanese Patent Laid-Open No. 63-264).
No. 692), an element having an organic light-emitting layer obtained by doping an 8-hydroxyquinoline aluminum complex as a host compound with a quinacridone dye (JP-A-3-25).
No. 5190) is known.

As described above, when light emission from excited singlet is used, the production ratio of singlet excitons and triplet excitons is 1 :.
Therefore, the limit of the external extraction quantum efficiency (η _ext ) is set to 5% because the generation probability of the luminescent excited species is 25% and the light extraction efficiency is about 20%.
However, Princeton et al. Reported on an organic EL device using phosphorescence emission from excited triplet (MA Baldo.
et al. , Nature, Volume 395, 151-1
Since page 54 (1998)), research on materials that exhibit phosphorescence at room temperature has become active (eg,
M. A. Baldo et al. , Nature, 4
Vol. 03, No. 17, pp. 750-753 (2000
), US Pat. No. 6,097,147). When the excited triplet is used, the upper limit of the internal quantum efficiency becomes 100%, so that in principle, the luminous efficiency is four times higher than that of the excited singlet, and the performance is almost the same as that of a cold cathode tube. It can be applied to and attracts attention.

It is needless to say that the host when the phosphorescent compound is used as a dopant is required to have an emission maximum wavelength in a region shorter than the emission maximum wavelength of the phosphorescent compound, but other requirements should be satisfied. I understand that there are conditions.

The 10th Internet
nal Workshop on Inorganic
and Organic Electrolumine
Science (EL '00, Hamamatsu) has made some reports on phosphorescent compounds. For example, I
Kai et al. use a hole-transporting compound as a host for a phosphorescent compound. In addition, M. E. Tampson et al. Use various electron-transporting materials as a host of a phosphorescent compound by doping them with a novel iridium complex. Furthermore, Tsutsui et al. Obtained high luminous efficiency by introducing a hole blocking layer.

Regarding the host compound of the phosphorescent compound,
For example, C.I. Adachi et al. , Appl. P
hys. Lett. , 77, 904 (2000
However, it is necessary to take a new approach from the viewpoint of the properties required for the host compound to obtain a high-brightness organic electroluminescent device.

[0011]

DISCLOSURE OF THE INVENTION The present invention has been made for the purpose of improving the light emission brightness, and an organic electroluminescence device having an improved light emission brightness, and a low power consumption using the organic electroluminescence device of the present invention. ,
A high-brightness display device is provided.

[0012]

The objects of the present invention have been achieved by the means described below.

1. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound is 0 or more and 0. An organic electroluminescence device having a wavelength of not more than 05 and having a maximum emission wavelength obtained by electroluminescence in a device state is longer than the maximum fluorescence wavelength of the fluorescent compound.

2. The ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound is 0 or more and 0.03 or less, and the organic electroluminescence device described in 1 above.

3. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) in the molecule of the fluorescent compound is larger than 0, And 0.
An organic electroluminescence device having a wavelength of less than 05 and having a maximum emission wavelength obtained by electroluminescence in a device-state is longer than the maximum fluorescence wavelength of the fluorescent compound.

4. The ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) in the molecule of the fluorescent compound is larger than 0, and
0.03 or less, The organic electroluminescent element of the said 3 characterized by the above-mentioned.

5. The maximum fluorescence wavelength of the fluorescent compound is 350
1 to 4 characterized in that it is from nm to 440 nm
The organic electroluminescence element according to any one of 1.

6. 6. The organic electroluminescence device according to any one of 1 to 5 above, wherein the fluorescent compound has a molecular weight of 600 or more.

7. 7. The organic electroluminescence device according to any one of 1 to 6 above, wherein the phosphorescence quantum yield in a solution of the phosphorescent compound is 0.01 or more at 25 ° C.

8. The hole transport layer adjacent to the light emitting layer, or the electron transport layer further contains at least one fluorescent compound, the fluorescent maximum wavelength of the fluorescent compound is from 350nm to 440nm, the above 1 7. The organic electroluminescence device according to any one of 7 above.

9. The fluorescence emission maximum wavelength of the fluorescent compound is 3
1 characterized in that it is 90 nm to 410 nm
7. The organic electroluminescence device according to any one of items 7 to 7.

10. 9. The organic electroluminescent device as described in 8 above, wherein the fluorescent compounds contained in the light emitting layer and the hole transporting layer or the electron transporting layer each have a fluorescence emission maximum wavelength of 390 nm to 410 nm.

11. At least 1 between the cathode and the light emitting layer
1 characterized in that it has a cathode buffer layer of a layer
10. The organic electroluminescence device according to any one of items 10 to 10.

12. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the fluorescent compound contains the compound represented by the general formula (I) and is in the state of being a device. The maximum emission wavelength obtained by electroluminescence of 1. is longer than the maximum fluorescence wavelength of the fluorescent compound.

13. In an organic electroluminescence device having a light-emitting layer containing both a fluorescent compound and a phosphorescent compound, the fluorescent compound contains the compound represented by the general formula (II), The maximum emission wavelength obtained by electroluminescence of 1. is longer than the maximum fluorescence wavelength of the fluorescent compound.

14. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the fluorescent compound contains a compound represented by the following general formula (III) The maximum emission wavelength obtained by electroluminescence of 1. is longer than the maximum fluorescence wavelength of the fluorescent compound.

15. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the fluorescent compound contains the compound represented by the general formula (IV), The maximum emission wavelength obtained by electroluminescence of 1. is longer than the maximum fluorescence wavelength of the fluorescent compound.

16. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the fluorescent compound contains the compound represented by the general formula (V) and becomes an element. The maximum emission wavelength obtained by electroluminescence of 1. is longer than the maximum fluorescence wavelength of the fluorescent compound.

17. The general formulas (I), (II) and (II
The ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound represented by I), (IV) or (V) is 0 or more and 0.05 or less. The organic electroluminescence device according to any one of 12 to 16.

18. The general formulas (I), (II) and (II
The ratio (N / C) of the number of nitrogen atoms to the number of carbon atoms in the molecule of the fluorescent compound represented by I), (IV) or (V) is greater than 0 and less than 0.05. 17. The organic electroluminescence device according to any one of 12 to 16 above, which is characterized.

19. 19. The organic electroluminescence device according to any one of 1 to 18 above, wherein the phosphorescent compound is a heavy metal complex compound.

20. 20. The organic electroluminescence device as described in 19 above, wherein the phosphorescent compound is a complex compound containing a Group VIII metal in the periodic table of elements as a central metal.

21. 20. The organic electroluminescence device as described in 19 above, wherein the phosphorescent compound is an osmium, iridium, or platinum complex compound.

22. 22. In any one of the above items 1 to 21, further containing at least one second fluorescent compound having a fluorescence maximum wavelength in a region having a longer wavelength than the maximum wavelength of light emitted from the phosphorescent compound. The organic electroluminescence device described.

23. 23. A display device comprising the organic electroluminescence element according to any one of 1 to 22 above.

24. 23. A full-color display device, wherein two or more kinds of the organic electroluminescent elements according to any one of 1 to 22 having different maximum wavelengths of light emission are juxtaposed on the same substrate.

The present invention will be described in detail below. The inventors of the present invention have conducted extensive studies on the fluorescent compound used as the host compound of the phosphorescent compound, and as a result, have found that the emission brightness of the device and the ratio of the number of nitrogen atoms and the number of carbon atoms in the molecule of the host compound (N / C ), There is a certain correspondence. As a result, when N / C takes a small value to some extent, further improvement in emission luminance was recognized. This is N
When / C becomes large to some extent, it is presumed that the emission brightness is limited due to some action of the nitrogen atom in the molecule of the host compound. Therefore, it was found that it is effective to reduce the N / C of the host compound in order to improve the emission brightness of the organic EL device using the phosphorescent compound as a dopant.

In the present invention, a fluorescent compound is a compound in which light emission from an excited singlet in which two electron spins are antiparallel to each other is observed by photoexcitation, and a phosphorescent compound is excited by photoexcitation. It is a compound in which light emission from an excited triplet in which electron spins are parallel is observed. Here, in the phosphorescent compound according to the present invention, an excited triplet state is formed at room temperature (15 to 30 ° C.) by energy transfer from the excited singlet state or the excited triplet state of the fluorescent compound. Is believed to be. Normal,
Phosphorescence was thought to be observable only at a low temperature of 77 ° K, but since the discovery of compounds capable of observing phosphorescence at room temperature in recent years, many compounds have focused on heavy metal complex compounds such as iridium complex compounds. Have been studied synthetically (for example, S. Lamansky et al., J. Am.
Chem. Soc. , 123, 4304, 20
2001).

In the present invention, the fluorescence maximum wavelength of the fluorescent compound is the maximum value when the fluorescence spectrum of the vapor deposition film when the fluorescent compound is vapor-deposited on a glass substrate to a thickness of 100 nm is measured.

In the present invention, in an organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the ratio (N / C) of the number of nitrogen atoms to the number of carbon atoms in the molecule is 0 or more and 0 or more. When a host compound of 0.05 or less was used in combination with a phosphorescent compound, a specific improvement in emission brightness was observed. Therefore, in the present invention, the fluorescent compound to be combined as the host of the phosphorescent compound is a nitrogen compound in the molecule. The ratio (N / C) of the number of carbon atoms to the number of carbon atoms is preferably 0 or more and 0.05 or less. The reason for this is not so clear, but as described above, when the ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) increases to some extent,
It is presumed that the emission brightness is limited due to some action of the nitrogen atom in the molecule of the host compound.

In the present invention, the fluorescent compound to be combined as the host of the phosphorescent compound has a ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) in the molecule of more than 0 and 0.03 or less. This is preferable because the light emission life is lengthened specifically. Although the reason for this is not so clear, it is preferable to use a host compound having a nitrogen atom in order to have a luminescence lifetime longer than a certain level, but the ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) is to some extent. It is presumed that the life is limited due to some action of nitrogen atoms when it becomes larger.

In the present invention, the maximum wavelength of phosphorescence emission of the phosphorescent compound incorporated as a dopant must be longer than that of the maximum fluorescence wavelength of the fluorescent compound of the host. This makes it possible to obtain an organic electroluminescence (EL) device utilizing the light emission by the excited triplet of the phosphorescent compound incorporated as a dopant.
Therefore, the maximum emission wavelength obtained by electroluminescence in the state where the device is configured is the maximum fluorescence wavelength of the fluorescent compound used as the host alone (fluorescence in a vapor deposition film when the fluorescent compound is vapor-deposited 100 nm on glass). It is a longer wave than the maximum value when the spectrum was measured).

In the present invention, the maximum fluorescent wavelength of the fluorescent compound used as the host compound is 350 nm to 440.
nm, more preferably 390 n
It is m-410 nm.

Further, the low molecular weight organic material has a poor thermal stability when the molecular weight is small, so that the emission brightness may not be sufficient. The fluorescent compound used as the host of the phosphorescent compound used in the present invention preferably has a molecular weight of 600 or more from the viewpoint of thermal stability.

The phosphorescent compound of the present invention has a phosphorescence quantum yield in solution of 0.001 or more at 25 ° C. It is preferably 0.01 or more. More preferably, 0.1
That is all.

The means for measuring the quantum yield φ _p in the excited triplet state and the theory therefor will be described below.

Excitation energy is lost from the excited singlet state to the ground state due to non-radiative transition and fluorescence emission at rate constants k _sn and k _f , respectively. In addition to this, a transition to an excited triplet state occurs with a rate constant, k _isc , and deactivates. Here, the lifetime of the excited singlet state, τ _s, is defined by the following equation.

Τ _s = (k _sn + k _f + _{ki sc} ) ^{−1 Further} , the quantum yield of fluorescence, φ _f is defined by the following equation.

Φ _f = k _f · τ _s Excited triplet state to ground state is deactivated by rate constants, k _tn and k _p by non-radiative transition and phosphorescence emission, respectively. The lifetime of the excited triplet state, τ _t, is defined by the following equation.

Τ _t = (k _tn + k _p ) ⁻¹ τ _t is 10 ⁻⁶ to 10 ⁻³ seconds, and a long one may reach several seconds. The quantum yield of phosphorescence, φ _p, is defined as follows using the quantum yield of excited triplet state generation, φ _ST .

Φ _p = φ _ST · k _p · τ _{t The} above parameters are the same as those in Spectroscopic II of 4th edition Experimental Chemistry Course 7.
It can be measured by the method described on page 98 (1992 version, Maruzen). Among the above parameters, the phosphorescence quantum yield in a solution of the phosphorescent compound can be measured using various solvents, but in the present invention, it is measured using tetrahydrofuran as the solvent.

Steric parameter E of the substituent in the present invention
s is a substituent constant defined by Taft, and is, for example, “Structure-Activity Correlation of Chemistry.
No. 22, published by Nankodo Publishing Co., Ltd. In particular, the Es value referred to in the present invention is based on a hydrogen atom, that is, the value of Es (H = 0), and the Es value defined as Es (CH ₃ = 0) based on a methyl group. The value obtained by subtracting 1.24 from is shown. The typical values are shown in Table 1.

[0053]

[Table 1]

The light emitting layer will be described below. In a broad sense, the light emitting layer as used herein refers to a layer that emits light when a current is applied to an electrode composed of a cathode and an anode. Specifically, it refers to a layer containing a fluorescent compound that emits light when a current is applied to an electrode composed of a cathode and an anode. In general, an electroluminescent element (EL element) has a structure in which a light emitting layer is sandwiched between a pair of electrodes. The organic EL device of the present invention has a hole transport layer, an electron transport layer, an anode buffer layer, a cathode buffer layer, and the like in addition to the light emitting layer as necessary, and has a structure sandwiched between a cathode and an anode.

Specifically, (i) anode / light emitting layer / cathode (ii) anode / hole transport layer / light emitting layer / cathode (iii) anode / light emitting layer / electron transport layer / cathode (iv) anode / positive Hole transport layer / light emitting layer / electron transport layer / cathode (v) anode / anode buffer layer / hole transport layer / light emitting layer /
There is a structure represented by electron transport layer / cathode buffer layer / cathode.

As a method of forming a light emitting layer using the above compound, there is a method of forming a thin film by a known method such as a vapor deposition method, a spin coating method, a casting method and an LB method. Preferably there is. Here, the molecular deposition film is a thin film formed by depositing the above compound in a vapor phase state, or a film formed by solidifying a molten state or a liquid phase state of the compound. Usually, this molecular deposition film can be distinguished from a thin film (molecular cumulative film) formed by the LB method, based on the difference in aggregation structure, higher order structure, and functional difference caused by it.

Further, this light emitting layer is disclosed in JP-A-57-517.
No. 81, it can be obtained by dissolving the above compound as a light emitting material together with a binder such as a resin in a solvent to form a solution, and then applying this solution by a spin coating method or the like to form a thin film. it can.

The thickness of the light emitting layer thus formed is not particularly limited and may be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.

Here, the phosphorescent compound according to the present invention is
Specifically, it is a heavy metal complex compound, preferably a complex compound having a Group VIII metal as a central metal in the periodic table of elements, and more preferably an osmium, iridium or platinum complex compound.

These phosphorescent compounds have a phosphorescence quantum yield of 0.001 or more at 25 ° C. as described above, and a phosphorescence emission maximum wavelength longer than the fluorescence maximum wavelength of the fluorescent compound serving as the host. Accordingly, for example, by using a phosphorescent compound having a wavelength longer than the maximum emission wavelength of the fluorescent compound as a host, the emission of the phosphorescent compound, that is, the maximum fluorescence wavelength of the host compound using the triplet state is obtained. It is possible to obtain an EL element that emits light at longer wavelengths. Therefore, the maximum wavelength of phosphorescence emission of the phosphorescent compound used is not particularly limited,
In principle, the emission wavelength obtained can be changed by selecting the central metal, the ligand, the substituent of the ligand, and the like.

For example, by using a fluorescent compound having a fluorescence maximum wavelength in the region of 350 nm to 440 nm as a host compound and using an iridium complex having phosphorescence in the green region, for example, an organic EL element which emits light in the green region by electroluminescence. Can be obtained.

Specific examples of the phosphorescent compound used in the present invention are shown below, but the invention is not limited thereto.
These compounds are described, for example, in Inorg. Chem. Four
Volume 0, 1704-1711 and the like.

[0063]

[Chemical 6]

[0064]

[Chemical 7]

[0065]

[Chemical 8]

In another embodiment, in addition to the fluorescent compound (A) as the host compound and the phosphorescent compound, it has a maximum fluorescence wavelength in a region longer than the maximum wavelength of light emitted from the phosphorescence compound. In some cases, at least one fluorescent compound (B) may be contained. In this case, energy transfer from the fluorescent compound (A) and the phosphorescent compound causes the organic E
As electroluminescence as the L element, light emission from the fluorescent compound (B) can be obtained. The fluorescent compound (B) is preferably one having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, and particularly preferably 30% or more. Specifically, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squaryl dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes, pyrylium dyes, perylene dyes, stilbene dyes ， Polythiophene dye,
Alternatively, a rare earth complex-based phosphor may be used.

The fluorescence quantum yield here can also be measured by the method described on page 362 (1992, Maruzen) of Spectroscopy II in the Fourth Edition Experimental Chemistry Course 7, and in the present invention, in tetrahydrofuran. To measure.

The fluorescent compound used in the present invention is a phosphorescent compound using a compound having a ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the fluorescent compound molecule of 0 or more and 0.05 or less as a host compound. It is preferable to use them together. This allows
Although it is possible to provide an organic EL device having higher emission brightness and excellent emission life, from another viewpoint, in the present invention, as the host compound used in combination with the phosphorescent compound, the compound represented by the general formula (I )-(V) are useful.

The following are the general formulas (I) to (I) in the present invention.
The compound represented by (V) will be described in detail.

In the general formula (I), n is 0 to 3
In which R ₁ and R ₂ each represent a substituent, and the substituent is preferably an alkyl group (methyl, ethyl, i
-Propyl, hydroxyethyl, methoxymethyl, trifluoromethyl, t-butyl, etc.), halogen atom (fluorine, chlorine, etc.), alkoxy group (methoxy, ethoxy, i
-Propoxy, butoxy, etc.). Ar represents an aromatic hydrocarbon ring or an aromatic heterocyclic group which may have a substituent, and preferably naphthyl, binaphthyl, quinolyl, isoquinolyl, benzoxazolyl, benzimidazolyl and the like. When n represents an integer of 2 or more, a plurality of R ₁ and R ₂ may be the same or different.

In the general formula (II), n4, n5 and n6
Each represents an integer of 0 to 7. One or more R ₆ , R ₇
And R ₈ each represents a substituent selected from an alkyl group, a cycloalkyl group, an aryl group, a halogen, an alkoxy group, an aryloxy group and a heterocyclic group, and a methyl group and a naphthyl group are particularly preferable.

When n4 to n6 represent an integer of 2 or more, a plurality of R _{6 to} R ₈ may be the same or different.

In the general formula (III), R _{11 to} R ₁₆ , X ₁
To X ₉ represent a hydrogen atom or a substituent, and may be different or the same. The group represented by R _{11 to} R ₁₆ is preferably an alkyl group (eg, methyl group, ethyl group, isopropyl group, trifluoromethyl group, t-butyl group, etc.). However, the total value of the three-dimensional parameters Es _{R11 to} Es _{R16 of} R _{11 to} R ₁₆ is Es.
_R11 + Es _R12 + Es _R13 + Es _R14 + Es _R15 + Es _R16 ≤
-2.0 is satisfied. In addition, adjacent substituents may be condensed with each other to form a ring structure. The substituent represented by X _{1 to} X ₉ is an alkyl group, an aryl group, a heterocyclic group,
Halogen atom, alkoxy group, amino group and the like are preferable,
In particular, X ₂ , X ₅ and X ₈ are more preferably an aryl group or an amino group (particularly a diarylamino group).

In the general formula (IV), R _{101 to} R ₁₂₈ each represent a hydrogen atom or a substituent, and R _{101 to} R ₁₀₄
At least one of the above represents a substituent. When R _{101 to} R ₁₂₈ represent a substituent, the substituent is preferably an alkyl group (eg, methyl group, ethyl group, isopropyl group, hydroxyethyl group, methoxymethyl group, trifluoromethyl group, perfluoropropyl group, perfluoropropyl group, Fluoro-n-butyl group, perfluoro-t-butyl group, t-butyl group, etc.), cycloalkyl group (eg, cyclopentyl group, cyclohexyl group, etc.), aralkyl group (eg, benzyl group, 2-phenethyl group, etc.), aryl Group (eg phenyl group, naphthyl group, p-tolyl group, p-chlorophenyl group etc.), alkoxy group (eg methoxy group, ethoxy group, isopropoxy group, butoxy group etc.), aryloxy group (eg phenoxy group etc.), An arylamino group (for example, a diphenylamino group, etc.) and the like can be mentioned. These groups may be further substituted, and as the substituent, a halogen atom, a hydrogen atom, a trifluoromethyl group,
Examples thereof include an alkyl group, an aryl group, an alkoxy group, an aryloxy group, an alkylthio group, a dialkylamino group, a dibenzylamino group, and a diarylamino group.

In the general formula (IV), the substituent of R _{101 to} R ₁₀₄ is preferably an alkyl group, and among them, R ₁₀₁
Most preferably, any two or four of R ₁₀₄ to R ₁₀₄ are methyl groups.

In the general formula (V), R _{201 to} R ₂₀₆ each represents a hydrogen atom or a substituent. R _{201 to} R ₂₀₆
When R represents a substituent, the substituent may be any of R ₁₀₁ to
The substituents mentioned in the examples of R ₁₂₈ are preferred. An aryl group or a substituted aryl group is more preferable, and a phenyl group or a substituted phenyl group is most preferable.

Among the compounds represented by the general formulas (I) to (V), the ratio of the number of nitrogen atoms to the number of carbon atoms in the molecule (N /
C) is preferably 0.05 or less, and most preferably the ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) in the molecule is 0.03 or less.

The following are the general formulas (I) to (I) in the present invention.
Specific examples of the compound represented by (V) are shown below, but the invention is not limited thereto.

[0079]

[Chemical 9]

[0080]

[Chemical 10]

[0081]

[Chemical 11]

[0082]

[Chemical 12]

[0083]

[Chemical 13]

[0084]

[Chemical 14]

[0085]

[Chemical 15]

[0086]

[Chemical 16]

[0087]

[Chemical 17]

[0088]

[Chemical 18]

[0089]

[Chemical 19]

[0090]

[Chemical 20]

[0091]

[Chemical 21]

[0092]

[Chemical formula 22]

[0093]

[Chemical formula 23]

[0094]

[Chemical formula 24]

[0095]

[Chemical 25]

[0096]

[Chemical formula 26]

[0097]

[Chemical 27]

[0098]

[Chemical 28]

[0099]

[Chemical 29]

[0100]

[Chemical 30]

[0101]

[Chemical 31]

[0102]

[Chemical 32]

[0103]

[Chemical 33]

[0104]

[Chemical 34]

[0105]

[Chemical 35]

[0106]

[Chemical 36]

[0107]

[Chemical 37]

[0108]

[Chemical 38]

The ratio (N / C) of the number of nitrogen atoms to the number of carbon atoms in the molecule which can be used in the present invention is 0 or more and 0.0 or more.
Examples of the fluorescent compound having 5 or less include those represented by the general formula (I).
In addition to the compounds represented by (V) to (V), the following compounds may be mentioned.

[0110]

[Chemical Formula 39]

The color emitted by the fluorescent compound of the present specification is
In Fig. 4.16 on page 108 of "Handbook of New Color Science" (edited by The Color Society of Japan, The University of Tokyo Press, 1985), the results measured by the spectral radiance meter CS-1000 (manufactured by Minolta) are shown in CIE chromaticity coordinates. It is determined by the color when fitted.

Since the compounds represented by the general formulas (I) to (V) have a high glass transition temperature (Tg), they have sufficient thermal stability as a material for an organic electroluminescence device. Tg is preferably 100 degrees or more.

The molecular weight of the compounds represented by formulas (I) to (V) is preferably 600 or more and 5000 or less. When the molecular weight is within this range, the light emitting layer can be easily produced by the vacuum vapor deposition method, and the production of the organic EL device becomes easy. Further, the thermal stability of the fluorescent compound in the organic EL device is improved.

Next, other layers constituting the EL device in combination with the light emitting layer such as the hole injecting layer, the hole transporting layer, the electron injecting layer and the electron transporting layer will be described.

The hole injection layer and the hole transport layer have a function of transmitting the holes injected from the anode to the light emitting layer. The hole injection layer and the hole transport layer are provided between the anode and the light emitting layer. By interposing, many holes are injected into the light emitting layer at a lower electric field, and moreover, the electrons injected from the cathode, the electron injection layer or the electron transport layer into the light emission layer, the holes are injected into the light emitting layer and the hole injection layer or the positive layer. Due to the electron barrier existing at the interface of the hole transport layer, the element is accumulated at the interface in the light emitting layer and the light emission efficiency is improved. The material of the hole injecting layer and the hole transporting layer (hereinafter referred to as the hole injecting material and the hole transporting material) has a property of transmitting the holes injected from the anode to the light emitting layer. There is no particular limitation as long as it is one
Conventionally, in an optical transmission material, an arbitrary material is selected and used from materials conventionally used as charge injection / transport materials for holes and known materials used in hole injection layers and hole transport layers of EL elements. be able to.

The above hole injecting material and hole transporting material have any of hole injecting or transporting and electron blocking properties, and may be either organic or inorganic.
Examples of the hole injection material and the hole transport material include triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, oxazoles. Examples thereof include derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aniline-based copolymers, and conductive polymer oligomers, especially thiophene oligomers. As the hole injecting material and the hole transporting material, the above materials can be used, but it is preferable to use a porphyrin compound, an aromatic tertiary amine compound and a styrylamine compound, particularly an aromatic tertiary amine compound. preferable.

Typical examples of the aromatic tertiary amine compound and the styrylamine compound are N, N, N ', N'.
-Tetraphenyl-4,4'-diaminophenyl; N,
N'-diphenyl-N, N'-bis (3-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine (TPD); 2,2-bis (4-di-p-tolyl) Aminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ′,
N'-tetra-p-tolyl-4,4'-diaminobiphenyl; 1,1-bis (4-di-p-tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2-methylphenyl ) Phenylmethane; bis (4-di-p-tolylaminophenyl) phenylmethane; N, N'-diphenyl-N, N'-di (4-methoxyphenyl) -4,4'-diaminobiphenyl; N,
N, N ', N'-tetraphenyl-4,4'-diaminodiphenyl ether; 4,4'-bis (diphenylamino) quadriphenyl; N, N, N-tri (p-tolyl) amine; 4- ( Di-p-tolylamino) -4'-
[4- (di-p-tolylamino) styryl] stilbene; 4-N, N-diphenylamino- (2-diphenylvinyl) benzene; 3-methoxy-4'-N, N-diphenylaminostilbenzene; N-phenyl Carbazoles, as well as those having in the molecule two fused aromatic rings as described in US Pat. No. 5,061,569, such as 4,4′-bis [N- (1-naphthyl) −
N-phenylamino] biphenyl (NPD), JP-A-4
No. 3,308,688 discloses three starburst-type linked triphenylamine units 4,
4 ', 4 "-tris [N- (3-methylphenyl) -N
-Phenylamino] triphenylamine (MTDAT
A) etc. are mentioned.

Further, it is also possible to use a polymer material in which these materials are introduced into the polymer chain, or where these materials are used as a polymer main chain.

Inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injecting material and the hole transporting material. The hole injecting layer and the hole transporting layer are formed by thinning the above hole injecting material and hole transporting material by a known method such as a vacuum vapor deposition method, a spin coating method, a casting method, and an LB method. Can be formed. The thickness of the hole injection layer and the hole transport layer is not particularly limited, but is usually about 5 nm to 5 μm. The hole injection layer and the hole transport layer may have a single layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

Further, the electron-transporting layer used as required may have a function of transmitting the electrons injected from the cathode to the light-emitting layer, and its material is any of conventionally known compounds. One can be selected and used.

Materials used for this electron transport layer (hereinafter, referred to as
Examples of the electron transport material) include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, heterocyclic tetracarboxylic acid anhydrides such as naphthaleneperylene, carbodiimides, fluorenylidene methane derivatives, anthraquinodimethane and Examples thereof include anthrone derivative and oxadiazole derivative. Furthermore, in the above oxadiazole derivative, a thiadiazole derivative in which an oxygen atom of the oxadiazole ring is substituted with a sulfur atom, or a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group can also be used as the electron transport material.

Further, a polymer material obtained by introducing these materials into a polymer chain or using these materials as a polymer main chain can also be used.

Further, metal complexes of 8-quinolinol derivatives, such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-).
Quinolinol) aluminum, tris (2-methyl-8)
-Quinolinol) aluminum, tris (5-methyl-)
8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metal of these metal complexes is In, Mg, Cu, Ca, Sn, Ga or Pb.
The metal complex replaced with can also be used as an electron transport material. In addition, metal-free or metal phthalocyanine, or those whose terminal is substituted with an alkyl group, a sulfonic acid group, or the like can be preferably used as the electron transport material. Further, the distyrylpyrazine derivative exemplified as the material of the light emitting layer can also be used as the electron transporting material, and like the hole injecting layer and the hole transporting layer, it is an inorganic material such as n-type-Si or n-type-SiC. Semiconductors can also be used as electron transport materials.

This electron transporting layer can be formed by forming the above compound by a known thin film forming method such as a vacuum vapor deposition method, a spin coating method, a casting method and an LB method. The thickness of the electron transport layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The electron-transporting layer may have a single-layer structure composed of one or more of these electron-transporting materials, or a laminated structure composed of a plurality of layers having the same composition or different compositions.

Further, in the present invention, the fluorescent compound is not limited to only the light emitting layer, and a fluorescent compound which becomes a host compound of the phosphorescent compound is provided in the hole transport layer or the electron transport layer adjacent to the light emitting layer. At least one fluorescent compound having a fluorescence maximum wavelength may be contained in the same region as the compound, which can further increase the emission efficiency of the EL device. The fluorescent compound contained in these hole transporting layer or electron transporting layer has a fluorescence maximum wavelength in the range of 350 nm to 440 nm, more preferably 390 nm to 410 nm, like the one contained in the light emitting layer. A compound is used.

The substrate preferably used in the organic EL device of the present invention is not particularly limited in the kind of glass, plastic, etc., and is not particularly limited as long as it is transparent.
Examples of the substrate preferably used for the electroluminescent element of the present invention include glass, quartz, and a light-transmissive plastic film.

As the light-transmissive plastic film,
For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyetherimide, polyether ether ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose Examples thereof include films made of acetate propionate (CAP) and the like.

Next, a suitable example for producing the organic EL element will be described. As an example, a method for manufacturing an EL device composed of the above-mentioned anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode will be described.

First, on a suitable substrate, a desired electrode material,
For example, a thin film made of an anode material is formed by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 10 to 200 nm to produce an anode. Then, a thin film composed of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer, which are element materials, is formed thereon.

Further, a buffer layer (electrode interface layer) may be provided between the anode and the light emitting layer or the hole injecting layer and between the cathode and the light emitting layer or the electron injecting layer.

The buffer layer is a layer provided between the electrode and the organic layer in order to reduce the driving voltage and improve the luminous efficiency.
2nd volume of "January 30 issued by TS Co., Ltd."
It is described in detail in Chapter “Electrode Materials” (pages 123 to 166), and includes an anode buffer layer and a cathode buffer layer.

The anode buffer layer is described in JP-A-9-4547.
The details are also described in No. 9, No. 9-260062, No. 8-288069 and the like, and as a specific example, a phthalocyanine buffer layer represented by copper phthalocyanine,
Examples thereof include an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) and polythiophene.

The cathode buffer layer is described in JP-A-6-3258.
No. 71, No. 9-17574, No. 10-74586, etc., the details are also described, and specifically, a metal buffer layer typified by strontium, aluminum, etc.,
Examples thereof include an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide and lithium oxide.

It is desirable that the buffer layer is a very thin film, and the film thickness is 0.1 to 10 depending on the material.
The range of 0 nm is preferred.

In addition to the above-mentioned basic constituent layers, if desired, layers having other functions may be laminated. For example, JP-A Nos. 11-204258 and 11-204359, and "organic EL element and its industrialization." Frontline (1998 1
It may have a functional layer such as a hole blocking (hole blocking) layer described in page 237, etc. of January 30, 30).

The buffer layer may function as a light emitting layer when at least one kind of the compound of the present invention is present in at least one of the cathode buffer layer and the anode buffer layer.

Next, the electrodes of the organic EL element will be described. The electrodes of the organic EL element consist of a cathode and an anode.

As the anode in this organic EL device,
A material having a high work function (4 eV or more), an alloy, an electrically conductive compound or a mixture thereof as an electrode material is preferably used. Specific examples of such electrode substances include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ and ZnO.

For the anode, a thin film of these electrode materials may be formed by a method such as vapor deposition or sputtering, and a pattern of a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much. (About 100 μm or more), a pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material. When the emitted light is taken out from this anode, it is desirable that the transmittance is higher than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, the film thickness depends on the material, but is usually 10 nm to 1 μm.
m, preferably 10 nm to 200 nm.

On the other hand, as the cathode, a metal having a low work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, or a mixture thereof as an electrode substance is used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum /
Aluminum oxide (Al ₂ O ₃ ) mixture, indium, lithium / aluminum mixture, rare earth metal and the like can be mentioned. Among these, from the viewpoint of electron injecting property and durability against oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value, for example, a magnesium / silver mixture or magnesium. Aluminium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, lithium / aluminum mixture and the like are suitable. The cathode is
These electrode materials can be produced by forming a thin film by a method such as vapor deposition or sputtering. The sheet resistance of the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually selected in the range of 10 nm to 1 μm, preferably 50 to 200 nm. In addition, since light is transmitted, it is convenient that either the anode or the cathode of the organic EL element is transparent or semi-transparent so that the light emission efficiency is improved.

Next, a method for manufacturing an organic EL element will be described. As a method for thinning the film, there are the spin coating method, the casting method, the vapor deposition method and the like as described above, but the vacuum vapor deposition method is preferable from the viewpoints that a uniform film is easily obtained and pinholes are not easily generated. When a vacuum vapor deposition method is used for thinning, the vapor deposition conditions are the type of compound used,
Generally, the boat heating temperature is 50 to 450 ° C., the degree of vacuum is 10 ⁻⁶ to 10 ⁻³ Pa, and the deposition rate is 0.01 to 50 nm, although it depends on the desired crystal structure, association structure, etc. of the molecular deposited film.
Second, substrate temperature is preferably -50 to 300 [deg.] C. and film thickness is 5 nm to 5 [mu] m.

As described above, a thin film of a desired electrode material, for example, an anode material, is vapor-deposited or sputtered on a suitable substrate to a film thickness of 1 μm or less, preferably 10 to 200 nm. Etc. to form an anode, and after forming a thin film of each layer consisting of a hole injection layer, a hole transport layer, a light emitting layer, and an electron transport layer / electron injection layer on the anode as described above, By forming a thin film made of a substance for a cathode on it by a method such as vapor deposition or sputtering so as to have a film thickness of 1 μm or less, preferably in the range of 50 to 200 nm, and by providing a cathode,
A desired organic EL device can be obtained. In this organic EL device, it is preferable to consistently manufacture from the hole injection layer to the cathode in this way by vacuuming once, but the manufacturing order is reversed, and the cathode, the electron injection layer, the light emitting layer, It is also possible to fabricate the hole injection layer and the anode in this order. When a direct current voltage is applied to the thus obtained organic EL element, light emission can be observed by applying a voltage of about 5 to 40 V with the anode having a positive polarity and the cathode having a negative polarity. Moreover, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the − state. The waveform of the alternating current applied may be arbitrary.

[0143]

The present invention will be described in detail below with reference to examples, but the embodiments of the present invention are not limited thereto.

Example 1 Electroluminescence element No. 1-1 to 1-22
Was prepared as follows.

<Production of Organic EL Element> 100 as anode
ITO on a glass substrate of mm × 100 mm × 1.1 mm
After patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) on which (indium tin oxide) was deposited to a thickness of 150 nm, the transparent supporting substrate provided with this ITO transparent electrode was ultrasonically cleaned with isopropyl alcohol and dried with nitrogen gas. After drying, the substrate was dried with UV ozone for 5 minutes.

This transparent support substrate was fixed to a substrate holder of a commercially available vacuum evaporation system, while 200 mg of α-NPD was put in a resistance heating boat made of molybdenum and 200 mg of CBP was put in another resistance heating boat made of molybdenum. Bathocuproine (BC) on another molybdenum resistance heating boat
200 mg, put 100 mg of Ir-1 (phosphorescent compound) in another molybdenum resistance heating boat, and further put 200 mg of Alq ₃ in another molybdenum resistance heating boat.
It was put in and attached to a vacuum vapor deposition apparatus. Then 4x vacuum chamber
After the pressure was reduced to 10 ⁻⁴ Pa, the heating boat containing α-NPD was energized to heat up to 220 ° C. and vapor-deposited on a transparent support substrate at a vapor deposition rate of 0.1 nm / sec to give a film thickness of 45.
nm hole transport layer was provided. Furthermore, CBP and Ir-1
Is heated to 220 ° C. by energizing the above heating boat containing the vapor deposition rate of 0.1 nm / sec and 0.01 n, respectively.
Co-deposition on the hole transport layer at a film thickness of 20 n
m emission layer was provided. The substrate temperature during vapor deposition was room temperature. Further, the heating boat containing BC is energized and heated to 250 ° C., vapor-deposited on the light-emitting layer at a vapor deposition rate of 0.1 nm / sec, and electron transport also having a role of blocking holes with a thickness of 10 nm. Layers were provided. On top of that, A
The heating boat containing 1q ₃ was energized and heated to 250 ° C., and vapor deposition was performed on the electron transport layer at a vapor deposition rate of 0.1 nm / sec to further provide an electron transport layer having a film thickness of 40 nm. The substrate temperature during vapor deposition was room temperature.

Next, the vacuum chamber was opened, and a rectangular perforated mask made of stainless steel was placed on the electron transport layer, while 3 g of magnesium was placed in a resistance heating boat made of molybdenum.
0.5 g of silver was placed in a tungsten vapor deposition basket, the vacuum chamber was decompressed again to 2 × 10 ⁻⁴ Pa, and a boat containing magnesium was energized to deposit a vapor deposition rate of 1.5 to 2.
Magnesium is vapor-deposited at 0 nm / sec, and at the same time, a silver basket is heated at a vapor deposition rate of 0.1 nm / se.
In the organic EL device No. No. 3 by depositing silver with the organic EL device No. c to form a counter electrode made of a mixture of magnesium and silver. 1
-1 (for comparison) was prepared.

In the above, the organic EL device No. 1 was manufactured by the same method except that the CBP and phosphorescent compound in the light emitting layer were replaced with the compounds shown in Table 2. 1-2 to 1-22 were produced.

The structures of the compounds used above are shown below.

[0150]

[Chemical 40]

<Organic EL Element No. Evaluation of Light-Emitting Luminance and Light-Emitting Life of Each of 1-1 to 1-22> Organic EL Element No. 1
At -1, a current started to flow at an initial drive voltage of 3 V, and light emission from the phosphorescent compound that was a dopant for the light emitting layer was exhibited.
Organic EL element No. The light emission luminance when a DC voltage of 9 V was applied in a dry nitrogen gas atmosphere at a temperature of 1-1 at 23 ° C. was measured using a CS-1000 manufactured by Minolta, and this value was 100.
Table 2 shows the value (relative value) of the emission luminance ratio of each sample of the organic EL device.

[0152]

[Table 2]

As is clear from Table 2, since the electroluminescence device using the compound of the present invention in the light emitting layer has a high emission brightness, it was found to be very useful as an organic EL device. The point became clear. (1) A device using a host compound having an N / C of 0.05 (5%) or less has a high emission luminance, and in particular, an N / C of 0.
When it is at most 03 (3%), the emission brightness is further improved. (2) Even if the N / C is 0.05 (5%) or less, the emission brightness is high when the fluorescence maximum wavelength of the host compound is 350 to 440 nm. (3) When N / C is 0.05 (5%) or less, the fluorescence maximum wavelength is 350 to 440 nm, and the molecular weight is 600 or more, the emission brightness is highest.

The phosphorescent quantum yields of the phosphorescent compounds of Ir-1, 2, 3, 5, 8, 9 were 0.36, 0.32, and 0.36, 0.32, respectively.
The values were 0.27, 0.12, 0.34 and 0.21.

The fluorescent maximum wavelength of the fluorescent compound serving as a host is the maximum value when the fluorescent spectrum of the vapor deposition film when the fluorescent compound is vapor-deposited on a glass substrate to a thickness of 100 nm is measured.

Example 2 Furthermore, the organic EL device No. For 1-1 to 1-22, the hole transport material is α-NPD (fluorescence maximum emission wavelength is 4
When an organic EL device was produced in exactly the same manner as in Example 1, except that 52 nm) was replaced with m-MTDATXA (fluorescent maximum emission wavelength was 399 nm), an improvement in emission brightness was observed.

[0157]

[Chemical 41]

Example 3 The cathode of the organic EL device produced in Example 1 was replaced with Al, and a cathode buffer layer was provided between the cathode and the electron transport layer.
Organic EL device No. 1 in Example 1 except that LiF was vapor-deposited at 0.5 nm to provide a cathode buffer layer. 1-1 ~
1-22, the organic EL element No. 3-1
3-22 was produced. When the emission brightness was measured using CS-1000 manufactured by Minolta in the same manner as in Example 1, organic E
L element No. 3-8 is the organic EL element No. 1-8
The emission luminance was 142 in relative comparison with. In addition, the organic EL element No. The introduction of the cathode buffer layer was also effective for the other elements among 3-1 to 3-22.

Example 4 Organic EL device No. 1 in Example 1 In 1-1 and 1-8, phosphorescent compounds were added from Ir-1 to Pt-3, respectively.
(2,3,7,8,12,13,17,18-octaethyl-21H-23H-porphine platinum (II)
(PtOEP); Porphyrin Products Co., Ltd.)
Except that the organic electroluminescence element No. 1 was replaced by the same procedure as in Example 1. 4-1 and 4-2 were produced.

Similarly, the organic EL element No. 1 in Example 1 was used. In 1-1 and 1-7, the phosphorescent compound was Ir-
Example 1 except that Pt-2 was used instead of 1
And the organic electroluminescence element N in exactly the same manner as
o. 4-3 and 4-4 were produced.

The emission luminance of these organic EL devices was measured. As a result, it was confirmed that in the organic electroluminescence device using the compound of the present invention, the emission brightness was improved.

When Pt-3 was used, red luminescence was obtained, and when Pt-2 was used, blue luminescence was obtained.

Example 5 In Example 1, the structure of the light emitting layer was changed to the fluorescent compound (7).
And a layer of 1 wt% DCM2 (light emitting layer A) is 1 nm
(7) and a layer of 10% by mass of Ir-1 (light-emitting layer B) in 1 n
m in the same manner as in Example 1 except that each layer was alternately laminated with 5 layers (total 10 nm). 5-1 was produced.

[0164]

[Chemical 42]

Organic EL element No. DCM in 5-1
Emission from 2 was observed at 590 nm.

Organic EL device No. 1 except that the fluorescent compound (7) was replaced with CBP. Comparative Organic EL Element No. 5-2 was produced. Organic EL element No. The emission from DCM2 is 590 nm from 5-2 as well.
However, the emission brightness was 0.60 times that when the fluorescent compound (7) was used, and it was found that the constitution of the present invention is more advantageous in terms of high brightness.

Example 6 The red, green and blue light emitting organic electroluminescent elements produced in Examples 1 and 4 were placed side by side on the same substrate to produce the active matrix type full color display device shown in FIG.

FIG. 1 shows only a schematic view of the display portion of the manufactured full-color display device. That is, on the same substrate, a wiring portion including a plurality of scanning lines 5 and data lines 6 and a plurality of pixels 3 arranged in parallel (pixels whose emission color is a red region, a green region pixel, a blue region pixel, etc.) are arranged. The scanning lines 5 and the plurality of data lines 6 of the wiring portion are each made of a conductive material, and the scanning lines 5 and the data lines 6 are orthogonal to each other in a grid pattern, and the pixels 3 are located at the orthogonal positions.
(Not shown in detail). The plurality of pixels 3
Are driven by an active matrix method in which an organic EL element corresponding to each emission color, a switching transistor which is an active element, and a drive transistor are provided, and when a scanning signal is applied from the scanning line 5, the data line is driven. An image data signal is received from 6 and light is emitted according to the received image data. In this way, each red, green,
Full-color display is possible by appropriately arranging blue pixels in parallel.

By driving the full-color display device, a clear full-color moving image display with high brightness was obtained.

Example 7 The organic EL device No. 1 of Example 1 was used. In the same manner as in 1-1, except that the compound of the light emitting layer and the phosphorescent compound were replaced with the compounds shown in Table 3, the organic EL device No. 7-
1-7-22 were produced.

At a temperature of each organic EL element of 23 ° C., the time required for halving the emission luminance (emission life) when applying a DC voltage of 9 V in a dry nitrogen gas atmosphere was measured to determine the organic EL element N.
o. It was expressed as a relative value when 7-1 was set to 100. Regarding the emission brightness [cd / m ² ], Minolta CS-100
It was measured using 0.

[0172]

[Table 3]

[0173]

[Chemical 43]

As is clear from Table 3, N / C of the present invention
A host compound having a value greater than 0 and less than 0.05, especially N / C
It has been found that an electroluminescence device using a host compound having a value of more than 0 and 0.03 or less in the light emitting layer has a long half-life of luminance (emission life), and thus is very useful as an organic EL device. .

[0175]

EFFECT OF THE INVENTION An organic electroluminescence device excellent in emission brightness and a display device of low power consumption using the organic electroluminescence device are obtained.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a display unit of an active matrix full-color display device.

[Explanation of symbols]

A display (display) 3 pixels 5 scan lines 6 data lines

─────────────────────────────────────────────────── ─── Continuation of front page (51) Int.Cl. ⁷ Identification code FI theme code (reference) H05B 33/22 H05B 33/22 BD (72) Inventor Hiroshi Kita No. 1 Sakuramachi, Hino City, Tokyo Konica Stocks Meeting Internal F-term (reference) 3K007 AB02 AB03 AB04 AB11 DB03

Claims (24)

[Claims] 1. In an organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound is N / C. , 0 or more and 0.05 or less,
In addition, the maximum emission wavelength obtained by electroluminescence in a state of being an element is a longer wave than the maximum fluorescence wavelength of the fluorescent compound, wherein the organic electroluminescence element is characterized. 2. The organic electroluminescence according to claim 1, wherein the ratio of the number of nitrogen atoms to the number of carbon atoms (N / C) in the molecule of the fluorescent compound is 0 or more and 0.03 or less. element. 3. In an organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, the ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound is (N / C). , Greater than 0 and 0.0
An organic electroluminescence device having a wavelength of less than 5 and having a maximum emission wavelength obtained by electroluminescence in a device state is longer than the maximum fluorescence wavelength of the fluorescent compound. 4. The ratio (N / C) of the number of nitrogen atoms to the number of carbon atoms in the molecule of the fluorescent compound is larger than 0 and is 0.
It is 03 or less, The organic electroluminescent element of Claim 3 characterized by the above-mentioned. 5. The fluorescence maximum wavelength of the fluorescent compound is 350 n.
It is m to 440 nm, It is characterized by the above-mentioned.
The organic electroluminescence element according to any one of 1. 6. The organic electroluminescence device according to claim 1, wherein the fluorescent compound has a molecular weight of 600 or more. 7. The organic electroluminescence device according to claim 1, wherein the phosphorescence quantum yield in the solution of the phosphorescent compound is 0.01 or more at 25 ° C. . 8. The hole transport layer adjacent to the light emitting layer or the electron transport layer further contains at least one fluorescent compound, and the fluorescent compound has a maximum fluorescence wavelength of 350 nm to 440 nm. The organic electroluminescence device according to claim 1, wherein 9. The fluorescence emission maximum wavelength of the fluorescent compound is 39.
2. The range from 0 nm to 410 nm.
7. The organic electroluminescence device according to any one of items 7 to 7. 10. The organic electroluminescence according to claim 8, wherein the fluorescent compound contained in the light emitting layer and the hole transporting layer or the electron transporting layer has a fluorescence emission maximum wavelength of 390 nm to 410 nm, respectively. element. 11. The method according to claim 1, further comprising at least one cathode buffer layer between the cathode and the light emitting layer.
10. The organic electroluminescence device according to any one of items 10 to 10. 12. An organic electroluminescence device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, wherein the fluorescent compound contains a compound represented by the following general formula (I), and the device The organic electroluminescence device is characterized in that the emission maximum wavelength obtained by electroluminescence in the above state is longer than the fluorescence maximum wavelength of the fluorescent compound. [Chemical 1] [Wherein, R ₁ and R ₂ each represent a substituent, Ar represents an aromatic hydrocarbon ring or an aromatic heterocyclic group which may have a substituent, and n represents an integer of 0 to 3] . ] 13. An organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, wherein the fluorescent compound contains a compound represented by the following general formula (II), and the device The organic electroluminescence device is characterized in that the emission maximum wavelength obtained by electroluminescence in the above state is longer than the fluorescence maximum wavelength of the fluorescent compound. [Chemical 2] [Wherein one or more R ₆ , R ₇ and R ₈ each represent a substituent selected from an alkyl group, a cycloalkyl group, an aryl group, a halogen, an alkoxy group, an aryloxy group and a heterocyclic group. , N4, n5 and n6 each represent an integer of 0 to 7. ] 14. An organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, wherein the fluorescent compound contains a compound represented by the following general formula (III), and the device The organic electroluminescence device is characterized in that the emission maximum wavelength obtained by electroluminescence in the above state is longer than the fluorescence maximum wavelength of the fluorescent compound. [Chemical 3] [In formula, R < ₁₁ > -R < ₁₆ > and X < ₁ > -X < ₉ > represent a hydrogen atom or a substituent, and they may differ, respectively and may be the same. However, the respective stereoscopic parameters Es _{R1 1} to R _{11 to} R ₁₆ of
The total value of Es _R16 is Es _R11 + Es _R12 + Es _R13 + E
s _R14 + Es _R15 + Es _R16 ≦ −2.0 is satisfied. ] 15. An organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, wherein the fluorescent compound contains a compound represented by the following general formula (IV), and the device The organic electroluminescence device is characterized in that the emission maximum wavelength obtained by electroluminescence in the above state is longer than the fluorescence maximum wavelength of the fluorescent compound. [Chemical 4] Wherein, R ₁₀₁ to R ₁₂₈ each represents a hydrogen atom, or a substituent, at least one of R ₁₀₁ to R _{1 04} represent a substituent. ] 16. An organic electroluminescent device having a light emitting layer containing both a fluorescent compound and a phosphorescent compound, wherein the fluorescent compound contains a compound represented by the following general formula (V), and the device The organic electroluminescence device is characterized in that the emission maximum wavelength obtained by electroluminescence in the above state is longer than the fluorescence maximum wavelength of the fluorescent compound. [Chemical 5] [In the formula, R _{201 to} R ₂₀₆ each represent a hydrogen atom or a substituent. ] 17. The general formulas (I), (II) and (II
The ratio (N / C) of the number of nitrogen atoms and the number of carbon atoms in the molecule of the fluorescent compound represented by I), (IV) or (V) is 0 or more and 0.05 or less. Item 12 to 16
The organic electroluminescence element according to any one of 1. 18. The general formula (I), (II), (II
The ratio (N / C) of the number of nitrogen atoms to the number of carbon atoms in the molecule of the fluorescent compound represented by I), (IV) or (V) is greater than 0 and less than 0.05. The organic electroluminescence device according to any one of claims 12 to 16, which is characterized in that. 19. The organic electroluminescence device according to claim 1, wherein the phosphorescent compound is a heavy metal complex compound. 20. The organic electroluminescence device according to claim 19, wherein the phosphorescent compound is a complex compound having a Group VIII metal in the periodic table of elements as a central metal. 21. The organic electroluminescence device according to claim 19, wherein the phosphorescent compound is an osmium, iridium, or platinum complex compound. 22. At least one second fluorescent compound having a fluorescent maximum wavelength is further contained in a region having a longer wavelength than the maximum wavelength of light emitted from the phosphorescent compound, and the second fluorescent compound is further contained. The organic electroluminescence element according to any one of 1. 23. A display device comprising the organic electroluminescence element according to claim 1. Description: 24. A full-color display characterized in that two or more kinds of the organic electroluminescence elements according to any one of claims 1 to 22 having light emission of different maximum wavelengths are juxtaposed on the same substrate. apparatus.