JP2000091074A - Organic electroluminescence element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide high luminance and stable red color light emission by including at least one kind of distyryl compound in an organic layer as an organic light emitting material. SOLUTION: A compound expressed by formula I is used as a distyryl compound contained in an organic layer. In formula I, R1, R2, R3 and R4 are mutually the same or different groups, and are an aryl group expressed by formula II. Here, in formula II, R13, R14, R15, R16 and R17 are mutually the same or different groups, and area hydrogen atom or at least one of them is a saturated or unsaturated alkoxyl group, an alkyl group, an amino group or an alkyl amino group. The alkyl group is desirably a methyl group and a t-butyl group. In formula I, R5, R6, R7, R8, R9, R10, R11 and R12 are mutually the same or different groups, and at least one of them is a cyano group, a nitro group or a halogen atom.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an organic electroluminescent device (organic EL device) in which an organic layer having a light emitting region is provided between an anode and a cathode.

[0002]

2. Description of the Related Art Flat panel displays having a light weight and high efficiency have been actively researched and developed, for example, for displaying screens of computers and televisions.

First, a cathode ray tube (CRT) is currently used most frequently as a display because of its high luminance and good color reproducibility, but has a problem that it is bulky, heavy and consumes high power.

Further, as a lightweight and highly efficient flat panel display, a liquid crystal display such as an active matrix drive has been commercialized. However, the liquid crystal display has a narrow viewing angle and is not self-luminous, so it consumes a large amount of power in a backlight in an environment with dark surroundings and high-definition high-speed video signals expected to be put to practical use in the future. And does not have sufficient response performance. In particular, it is difficult to manufacture a display having a large screen size, and there are also problems such as high cost.

[0005] As an alternative to this, there is a possibility of a display using light emitting diodes, but there are also problems such as high manufacturing costs and difficulty in forming a matrix structure of light emitting diodes on one substrate. However, as a low-cost display candidate to replace a cathode ray tube, there is a large problem until commercialization.

Recently, an organic electroluminescent device (organic EL device) using an organic luminescent material has been attracting attention as a flat panel display that can solve these problems. That is, by using an organic compound as a light emitting material, realization of a flat panel display which is self-luminous, has a high response speed, and has no viewing angle dependence is expected.

The structure of the organic electroluminescent device is such that an organic thin film containing a light emitting material which emits light by current injection is formed between a translucent positive electrode and a metal cathode. CW Tan
g, SA VanSlyke et al., Applied Physics Letters No. 51
In a research report published in Vol. 12, No. 913 to 915 (1987), an organic thin film was formed as a two-layer structure of a thin film made of a hole transporting material and a thin film made of an electron transporting material, and each of the organic thin films was formed from the respective electrodes through the organic film. A device structure that emits light by recombination of electrons and holes injected into the device has been developed (single heterostructure organic EL device).

In this device structure, either the hole transporting material or the electron transporting material also serves as a light emitting material, and light emission occurs in a wavelength band corresponding to an energy gap between a ground state and an excited state of the light emitting material. With such a two-layer structure, a drastic reduction in driving voltage and an improvement in luminous efficiency were performed.

Then, C. Adachi, S. Tokita, T. Tsu
Japanese Journal of Applied Phy such as tsui and S. Saito
sics Vol. 27, No. 2, pp. L269-L271 (1988)
As described in the published research report, a three-layer structure (organic EL device having a double hetero structure) of a hole transport material, a light-emitting material, and an electron transport material has been developed, and furthermore, CW Tang,
Journal of Applied by SA VanSlyke, CH Chen, etc.
Physics Vol. 65, No. 9, pp. 3610-3616 (1989)
As described in the published research report, a device structure in which a light-emitting material is included in an electron transport material has been developed. These studies have verified the possibility of high-luminance light emission at low voltage, and in recent years, research and development have been very active.

The diversity of the organic compounds used for the light emitting material has the advantage that the emission color can be arbitrarily changed by changing the molecular structure theoretically. Therefore, by performing molecular design, R (red) and G with good color purity required for full color display can be obtained.
It can be said that it is easier to make the three colors (green) and B (blue) uniform than a thin film EL element using an inorganic substance.

[0011]

However, there is a problem that has to be actually solved in the organic electroluminescent device. It is difficult to develop a stable and high-luminance red light-emitting element, and as a currently reported electron transport material, tris (8-quinolinol) aluminum (hereinafter referred to as Alq ₃₎
Abbreviation. ) In DCM [4-dicyanomethylene-6- (p
-Dimethylaminostyryl) -2-methyl-4H-pyran] also has the highest luminance,
Neither reliability is satisfactory as a display material.

In addition, T. Tsutsui, DUKim has an Inorganic an
d Organic electroluminescence conference (1996, Be
rlin) reported at 1000 cd.
/ M ² or higher, but the chromaticity of red corresponding to full color is not perfect.

At present, the realization of a red light emitting element having high luminance, stability and high color purity is desired.

Japanese Patent Application Laid-Open No. Hei 7-188649 (Japanese Patent Application No. 6-148798) proposes that a specific distyryl compound be used as an organic electroluminescent material.
The target emission color is blue, not red.

An object of the present invention is to provide an organic electroluminescent device having high luminance and stable red light emission.

[0016]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present invention has revealed that the use of a specific distyryl compound as a light-emitting material makes it possible to realize a stable and highly luminous full-color display. The inventors have found that a red light-emitting element having high performance can be provided, and have reached the present invention.

That is, the present invention relates to an organic electroluminescent device in which an organic layer having a light emitting region is provided between an anode and a cathode, and includes an organic substance which emits light by current injection as a constituent element. Wherein at least one of the distyryl compounds represented by the general formula (1) or the following general formula (3) is contained as an organic light-emitting material,
The present invention relates to an organic electroluminescent device.

Embedded image [However, in the general formula (1), R ¹ , R ² , R ³
And R ⁴ are the same or different groups and are aryl groups represented by the following general formula (2) (However, in the general formula (2), R ¹³ , R ¹⁴ ,
R ¹⁵ , R ¹⁶ and R ¹⁷ are the same or different groups, and each is a hydrogen atom, or at least one of them is a saturated or unsaturated alkoxyl group, or an alkyl group (methyl group,
Tertiary butyl groups are preferred. ), An amino group or an alkylamino group. ), R ⁵ , R ⁶ , R ⁷ , R ⁸ ,
R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different groups and at least one of them is a cyano group, a nitro group or a halogen atom (this includes F, Cl, Br, I). ). ] [However, in the general formula (3), R ¹⁸ , R ¹⁹ ,
R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ are the same or different groups, and at least one of them is a cyano group, a nitro group or a halogen atom (including F, Cl,
Br and I. ). ]

By using a distyryl compound represented by the above general formula (1) and / or (3) as a luminescent material, high-luminance and stable red luminescence can be obtained, and the electrical, thermal or chemical stability can be obtained. An element excellent in the above can be provided. The distyryl compounds represented by the general formula (1) or (3) can be used alone or in combination.

The distyryl compound used in the organic electroluminescent device of the present invention will be described.

In the organic electroluminescent device of the present invention, the distyryl compound represented by the general formula (1), which is a luminescent material, is, for example, represented by the following structural formulas (4) -1, (4) -2, and (4)
-3, (4) -4, (4) -5, (4) -6 or (4)
At least one molecular structure such as -7 can be used. These are all bis (aminostyryl) anthracene compounds having an alkoxy (or alkyl) phenyl group or an unsubstituted phenyl group.

Embedded image

FIGS. 1 to 4 show examples of an organic electroluminescent device according to the present invention.

FIG. 1 shows a transmissive organic electroluminescent device A in which emitted light 20 passes through the cathode 3, and the emitted light 20 can also be observed from the protective layer 4 side. FIG. 2 shows a reflective organic electroluminescent element B in which the reflected light from the cathode 3 is also obtained as the emitted light 20.

In the figure, reference numeral 1 denotes an organic electroluminescent device.
Substrates for glass, plastic and other suitable
Materials can be used. In addition, organic electroluminescent elements
When used in combination with other display elements, the substrate
Can also be used. 2 is a transparent electrode (anode);
TO (Indium tin oxide), SnO _Two
Etc. can be used.

Reference numeral 5 denotes an organic light emitting layer, which contains the above distyryl compound as a light emitting material. With respect to this light-emitting layer, conventionally known various structures can be used as a layer structure for obtaining the organic electroluminescence 20. As will be described later, for example, when a material constituting either the hole transport layer or the electron transport layer has a light emitting property, a structure in which these thin films are laminated can be used. Further, in order to improve the charge transporting performance in a range satisfying the object of the present invention, one or both of the hole transporting layer and the electron transporting layer has a structure in which thin films of a plurality of types of materials are stacked, or a plurality of types of materials. It does not prevent the use of a thin film having a mixed composition. Further, in order to improve the light emitting performance, at least one kind of fluorescent material is used, and the thin film is sandwiched between the hole transport layer and the electron transport layer. May be used in the hole transport layer, the electron transport layer, or both. In these cases, a thin film for controlling the transport of holes or electrons can be included in the layer structure in order to improve the luminous efficiency.

Since the distyryl compound exemplified in the above structural formula (4) has both electron transporting performance and hole transporting performance, it can be used as a light emitting layer which also serves as an electron transporting layer in the device structure.
Alternatively, it can be used also as a light emitting layer which also serves as a hole transport layer. Further, it is also possible to adopt a configuration in which the distyryl compound is used as a light-emitting layer and sandwiched between an electron transport layer and a hole transport layer.

In FIGS. 1 and 2, reference numeral 3 denotes a cathode;
As the electrode material, an alloy of an active metal such as Li, Mg, and Ca and a metal such as Ag, Al, and In, or a structure in which these are laminated can be used. In a transmission type organic electroluminescent device, by adjusting the thickness of the cathode, a light transmittance suitable for the intended use can be obtained. Also, FIG.
The effect is enhanced by forming the protective layer so as to cover the entire organic electroluminescent element. If airtightness is maintained,
Any suitable material can be used. Reference numeral 8 denotes a drive power supply for current injection.

In the organic electroluminescent device according to the present invention, the organic layer has an organic laminated structure (single heterostructure) in which a hole transport layer and an electron transport layer are laminated, and the organic layer has a hole transport layer or an electron transport layer. The distyryl compound may be used as a material for forming the transport layer. Alternatively, the organic layer has an organic laminated structure (double hetero structure) in which a hole transport layer, a light emitting layer, and an electron transport layer are sequentially laminated, and the distyryl compound is used as a material for forming the light emitting layer. Good.

FIG. 3 shows an example of an organic electroluminescent device having such an organic laminated structure.
It has a laminated structure in which a translucent anode 2, an organic layer 5 a including a hole transport layer 6 and an electron transport layer 7, and a cathode 3 are sequentially laminated, and this laminated structure is sealed with a protective film 4. This is an organic electroluminescent device C having a single hetero structure.

As shown in FIG. 3, in the case of a layer configuration in which the light emitting layer is omitted, light emission 20 of a predetermined wavelength is generated from the interface between the hole transport layer 6 and the electron transport layer 7. These light emissions are observed from the substrate 1 side.

FIG. 4 shows a light-transmitting anode 2, an organic layer 5 b composed of a hole transport layer 10, a light-emitting layer 11 and an electron transport layer 12, and a cathode 3 on a light-transmitting substrate 1. Is a double hetero-structure organic electroluminescent element D having a laminated structure in which are sequentially laminated, and the laminated structure is sealed with a protective film 4.

In the organic electroluminescent device shown in FIG. 4, when a DC voltage is applied between the anode 2 and the cathode 3, the holes injected from the anode 2 pass through the hole transport layer 10, The electrons injected from 3 reach the light emitting layer 11 via the electron transport layer 12 respectively. As a result, electron / hole recombination occurs in the light emitting layer 11 to generate singlet excitons, and the singlet excitons emit light of a predetermined wavelength.

In each of the organic electroluminescent elements C and D described above, the substrate 1 can be made of a light-transmissive material such as glass, plastic, or the like. The substrate may be shared when used in combination with another display element or when the stacked structures shown in FIGS. 3 and 4 are arranged in a matrix. In addition, each of the elements C and D can take any structure of a transmission type and a reflection type.

The anode 2 is a transparent electrode and is made of ITO.
(Indium tin oxide) and SnO ₂ can be used. A thin film made of an organic substance or an organometallic compound may be provided between the anode 2 and the hole transport layer 6 (or the hole transport layer 10) for the purpose of improving the charge injection efficiency. When the protective film 4 is formed of a conductive material such as a metal,
An insulating film may be provided on the side surface of the anode 2.

The organic layer 5a in the organic electroluminescent device C is an organic layer in which a hole transport layer 6 and an electron transport layer 7 are laminated, and one or both of them contain the distyryl compound described above. The light emitting hole transport layer 6 or the electron transport layer 7 may be used. The organic layer 5b in the organic electroluminescent element D is an organic layer in which the hole transport layer 10, the light emitting layer 11 containing the distyryl compound described above, and the electron transport layer 12 are laminated. Can be taken. For example, one or both of the hole transport layer and the electron transport layer may have a light emitting property.

In particular, it is desirable that the hole transport layer 6, the electron transport layer 7, and the light emitting layer 11 are layers composed of the distyryl compound of the present invention. Alternatively, it may be formed by co-evaporation of the distyryl compound and another hole or electron transport material (for example, aromatic amines or pyrazolines). Further, in the hole transport layer, a hole transport layer in which a plurality of types of hole transport materials are stacked may be formed in order to improve hole transport performance.

In the organic electroluminescent device C, the light emitting layer may be the electron transporting light emitting layer 7. However, depending on the voltage applied from the power supply 8, the light emitting layer may emit light at the hole transporting layer 6 or its interface. There is. Similarly, in the organic electroluminescent device D, the light emitting layer may be the electron transport layer 12 or the hole transport layer 10 other than the layer 11. In order to improve the light emitting performance, it is preferable that the light emitting layer 11 using at least one kind of fluorescent material is sandwiched between the hole transport layer and the electron transport layer. Alternatively, a structure in which this fluorescent material is contained in the hole transporting layer or the electron transporting layer, or both of them may be configured. In such a case, in order to improve the luminous efficiency, a thin film (such as a hole blocking layer or an exciton generation layer) for controlling the transport of holes or electrons can be included in the layer configuration.

The material used for the cathode 3 is L
An alloy of an active metal such as i, Mg, Ca or the like and a metal such as Ag, Al, In or the like can be used, and a structure in which these metal layers are laminated may be used. Incidentally, by appropriately selecting the thickness and material of the cathode, an organic electroluminescent device suitable for the intended use can be produced.

The protective film 4 functions as a sealing film, and by having a structure covering the entire organic electroluminescent element, the charge injection efficiency and the luminous efficiency can be improved. As long as the airtightness is maintained, the material can be appropriately selected such as a single metal such as aluminum, gold, and chromium, or an alloy.

The current applied to each of the above-mentioned organic electroluminescent elements is usually a direct current, but a pulse current or an alternating current may be used. The current value and the voltage value are not particularly limited as long as they are within a range that does not cause element destruction. However, in consideration of power consumption and life of the organic electroluminescent element, it is desirable to emit light efficiently with as little electric energy as possible.

Next, FIG. 5 shows a configuration example of a flat display using the organic electroluminescent device of the present invention. As shown, for example, in the case of a full color display, an organic layer 5 (5a, 5b) capable of emitting three primary colors of red (R), green (G) and blue (B) is provided between the cathode 3 and the anode 2. It is arranged in. The cathode 3 and the anode 2 can be provided in a stripe shape crossing each other, and are selected by the luminance signal circuit 14 and the control circuit 15 with a built-in shift register, and a signal voltage is applied to each of them. The organic layer at a position (pixel) where the anode 3 and the anode 2 intersect is configured to emit light.

That is, FIG. 5 shows a simple matrix of 8 × 3 RGB, for example, in which a laminate 5 comprising a hole transport layer and at least one of a light emitting layer and an electron transport layer is provided between the cathode 3 and the anode 2. (FIG. 3 or FIG. 4)
reference). The cathode and the anode are both patterned in a stripe shape, are orthogonal to each other in a matrix, are applied with a signal voltage in a time series by the control circuits 15 and 14 having a built-in shift register, and are configured to emit light at the intersection thereof. It is something. The EL element having such a configuration can be used not only as a display for characters and symbols, but also as an image reproducing device. Further, it is possible to form a multi-color or full-color all-solid-state flat panel display by arranging stripe patterns of the cathode 3 and the anode 2 for each color of red (R), green (G), and blue (B). Become.

[0042]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited to the following Examples.

Example 1 In this example, among the distyryl compounds represented by the general formula (1), the following structural formula (4) having a cyano group at R ⁸ and R ¹² was prepared.
In this example, an organic electroluminescent device having a single hetero structure was manufactured using the compound No. 1 as a hole transporting light emitting material.

Embedded image

First, a 30 mm-thick anode made of ITO having a thickness of 100 nm was formed on one surface in a vacuum evaporation apparatus.
A 30 mm glass substrate was set. A plurality of metal masks each having a unit opening of 2.0 mm × 2.0 mm are arranged in close proximity to the substrate as an evaporation mask, and the above-mentioned structural formula (4) -1 is obtained by a vacuum evaporation method under a vacuum of 10 ⁻⁴ Pa or less.
Was formed as a hole transport layer (also serving as a light emitting layer) to a thickness of, for example, 50 nm. The deposition rate was 0.1 nm / sec.

Further, Alq ₃ (tris (8-quinolinol) aluminum) having the following structural formula is used as an electron transporting material.
Was deposited in contact with the hole transport layer. The thickness of the electron transport layer made of Alq ₃ was also set to, for example, 50 nm, and the deposition rate was set to 0.2 nm / sec.

Embedded image

As a cathode material, a laminated film of Mg and Ag is employed, and this is also deposited by vapor deposition at a deposition rate of 1 nm / sec, for example, 50 nm (Mg film) and 150 nm (Ag film).
The organic electroluminescent device according to Example 1 as shown in FIG.

The organic electroluminescent device of Example 1 thus manufactured was evaluated for luminous characteristics by applying a forward bias DC voltage in a nitrogen atmosphere. It emitted a red light, which was found by spectrometry to have a peak at 685 nm, as shown in FIG. For spectrometry, a spectroscope using a photodiode array manufactured by Otsuka Electronics Co., Ltd. as a detector was used. When voltage-luminance measurement was performed, as shown in FIG. 10, a luminance of 2000 cd / m ² was obtained at 8 V.

After this organic electroluminescent device was manufactured, it was left under a nitrogen atmosphere for one month, but no device deterioration was observed. In addition, when the current was supplied at a constant value at an initial luminance of 300 cd / m ² to continuously emit light and was forcibly deteriorated, it took 1200 hours for the luminance to be reduced by half.

Example 2 In this example, among the distyryl compounds of the general formula (1), the above-mentioned structural formula (4)-having a cyano group at R ⁸ and R ^12.
In this example, an organic electroluminescent device having a single hetero structure was manufactured using the compound No. 1 as an electron transporting light emitting material.

First, in a vacuum deposition apparatus, a 30 mm-thick anode made of ITO having a thickness of 100 nm was formed on one surface.
A 30 mm glass substrate was set. As a deposition mask, a plurality of metal masks each having a unit opening of 2.0 mm × 2.0 mm are arranged close to the substrate, and α-N of the following structural formula is formed by a vacuum deposition method under a vacuum of 10 ⁻⁴ Pa or less.
PD (α-naphthylphenyldiamine) is, for example, 50n
The film was formed as a hole transport layer to a thickness of m. The deposition rate was 0.1 nm / sec.

Embedded image

Further, the compound of the above structural formula (4) -1 was deposited as an electron transporting material in contact with the hole transporting layer. The thickness of the electron transporting layer (also serving as a light emitting layer) made of the compound of the above structural formula (4) -1 is also, for example, 50 nm, and the deposition rate is 0.1 mm.
2 nm / sec.

As a cathode material, a laminated film of Mg and Ag is employed, which is also deposited at a deposition rate of 1 nm / sec, for example, 50 nm (Mg film) and 150 nm (Ag film).
To produce an organic electroluminescent device according to Example 2 as shown in FIG.

The organic electroluminescent device of Example 2 thus manufactured was evaluated for luminous characteristics by applying a forward bias DC voltage under a nitrogen atmosphere. The emission color was red, and the result of spectroscopic measurement performed in the same manner as in Example 1 showed that the emission color was 68 as shown in FIG.
A spectrum having an emission peak at 5 nm was obtained. Also,
When a voltage-luminance measurement was performed, as shown in FIG.
A luminance of 2100 cd / m ² was obtained at 8 V.

After this organic electroluminescent device was manufactured, it was left under a nitrogen atmosphere for one month, but no device deterioration was observed. In addition, when the current was supplied at a constant value at an initial luminance of 300 cd / m ² to continuously emit light and was forcibly deteriorated, it took 1,000 hours until the luminance was reduced to half.

Example 3 In this example, among the distyryl compounds of the general formula (1), the above-mentioned structural formula (4)-having a cyano group at R ⁸ and R ^12.
In this example, an organic electroluminescent device having a double hetero-layer structure was manufactured using Compound 1 as a light emitting material.

First, in a vacuum evaporation apparatus, a 30 mm-thick anode made of ITO having a thickness of 100 nm was formed on one surface.
A 30 mm glass substrate was set. As a vapor deposition mask, a metal mask having a plurality of 2.0 mm × 2.0 mm unit openings is arranged close to the substrate, and the α-N of the above structural formula is formed by a vacuum vapor deposition method under a vacuum of 10 ⁻⁴ Pa or less.
PD was formed as a hole transport layer to a thickness of, for example, 30 nm. The deposition rate was 0.2 nm / sec.

Further, as a light emitting material, the above structural formula (4)
Compound -1 was deposited in contact with the hole transport layer. The thickness of the light emitting layer made of the compound of the above structural formula (4) -1 is also, for example, 3
0 nm, and the deposition rate was 0.2 nm / sec.

Further, Alq ₃ having the above structural formula was deposited as an electron transporting material in contact with the light emitting layer. The thickness of Alq _{3 was} , for example, 30 nm, and the deposition rate was 0.2 nm / sec.

As a cathode material, a laminated film of Mg and Ag is adopted, and this is also deposited by vapor deposition at a deposition rate of 1 nm / sec, for example, 50 nm (Mg film) and 150 nm (Ag film).
To produce an organic electroluminescent device according to Example 3 as shown in FIG.

The organic electroluminescent device of Example 3 fabricated as described above was evaluated for luminous characteristics by applying a forward bias DC voltage under a nitrogen atmosphere. It emitted a red light, which was found by spectrometry to have a peak at 685 nm, as shown in FIG. When a voltage-luminance measurement was performed, as shown in FIG. 12, 2400 cd / m at 8 V
A luminance of ² was obtained.

After the organic electroluminescent device was manufactured, the device was allowed to stand for one month in a nitrogen atmosphere, but no device deterioration was observed. In addition, when the current was supplied at a constant value at an initial luminance of 300 cd / m ² to continuously emit light and was forcibly deteriorated, it took 2,000 hours to reduce the luminance by half.

Example 4 The layer structure and the film forming method were the same as in Example 2 except that TPD (triphenyldiamine derivative) having the following structural formula was used in place of α-NPD as the hole transporting material. An electroluminescent device was manufactured.

Embedded image

The organic electroluminescent device of this example also emitted red light similar to that of Example 2. As a result of the spectroscopic measurement, the spectrum coincided with the spectrum of the organic electroluminescent device of Example 2.

Example 5 In this example, among the above distyryl compounds of the general formula (1), 4-methoxyphenyl groups were substituted for R ² and R ³ , and R ⁸ and R
^This is an example in which a compound having a single hetero structure was produced using a compound of the following structural formula (4) -2 having a cyano group as a hole transporting luminescent material.

Embedded image

First, in a vacuum deposition apparatus, a 30 mm-thick anode made of ITO having a thickness of 100 nm was formed on one surface.
A 30 mm glass substrate was set. As a deposition mask, a plurality of metal masks each having a unit opening of 2.0 mm × 2.0 mm are arranged close to the substrate, and the above-mentioned structural formula (4) -2 is formed by a vacuum deposition method under a vacuum of 10 ⁻⁴ Pa or less.
Was formed as a hole transport layer (also serving as a light emitting layer) to a thickness of, for example, 50 nm. The deposition rate was 0.1 nm / sec.

Further, Alq ₃ (tris (8-quinolinol) aluminum) of the above structural formula is used as an electron transporting material.
Was deposited in contact with the hole transport layer. The thickness of the electron transport layer made of Alq ₃ was also set to, for example, 50 nm, and the deposition rate was set to 0.2 nm / sec.

As a cathode material, a laminated film of Mg and Ag is employed, and this is also deposited by vapor deposition at a deposition rate of 1 nm / sec, for example, 50 nm (Mg film) and 150 nm (Ag film).
Then, an organic electroluminescent device as shown in FIG. 3 according to Example 5 was produced.

The organic electroluminescent device of Example 5 thus manufactured was evaluated for luminous characteristics by applying a forward bias DC voltage under a nitrogen atmosphere. It emitted red light. By spectral analysis, as shown in FIG. 9, a spectrum having a light emission peak at 695 nm was obtained. For spectrometry, a spectroscope using a photodiode array manufactured by Otsuka Electronics Co., Ltd. as a detector was used. When voltage-luminance measurement was performed, a luminance of 1800 cd / m ² was obtained at 8 V as shown in FIG.

After this organic electroluminescent device was manufactured, it was left under a nitrogen atmosphere for one month, but no device deterioration was observed. In addition, when the current was supplied at a constant value at an initial luminance of 300 cd / m ² to continuously emit light and was forcibly deteriorated, it took 1,000 hours until the luminance was reduced to half.

[0070]

According to the organic electroluminescent device of the present invention, in an organic electroluminescent device in which an organic layer having a light emitting region is provided between an anode and a cathode, the organic layer has the general formula (1) ) Or at least one of the distyryl compounds represented by (3), it is possible to provide an organic electroluminescent device having high luminance and stable red light emission.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view of a main part of an organic electroluminescent device according to the present invention.

FIG. 2 is a schematic sectional view of another main part of the organic electroluminescent device.

FIG. 3 is a schematic cross-sectional view of another main part of the same organic electroluminescent device.

FIG. 4 is a schematic cross-sectional view of another main part of the organic electroluminescent device.

FIG. 5 is a configuration diagram of a full-color flat display using the organic electroluminescent element.

FIG. 6 is an emission spectrum diagram of the organic electroluminescent device according to Example 1 of the present invention.

FIG. 7 is an emission spectrum diagram of the organic electroluminescent device according to Example 2;

FIG. 8 is an emission spectrum diagram of the organic electroluminescent device according to Example 3 of the present invention.

FIG. 9 is an emission spectrum diagram of the organic electroluminescent device according to Example 5.

FIG. 10 is a voltage-luminance characteristic diagram of the organic electroluminescent device according to Example 1.

FIG. 11 is a voltage-luminance characteristic diagram of the organic electroluminescent device according to Example 2;

FIG. 12 is a voltage-luminance characteristic diagram of the organic electroluminescent element according to Example 3.

FIG. 13 is a voltage-luminance characteristic diagram of the organic electroluminescent device according to Example 5.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Substrate, 2 ... Transparent electrode (anode), 3 ... Cathode, 4 ... Protective film, 5 5a, 5b ... Organic layer, 6 ... Hole transport layer, 7 ... Electron transport layer, 8 ... Power supply, 10 ... Positive Hole transporting layer, 11 light emitting layer, 12 electron transporting layer, 14 luminance signal circuit, 15 control circuit, 20 light emission, A, B, C, D organic electroluminescent element

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Shinichiro Tamura 6-35, Kita-Shinagawa, Shinagawa-ku, Tokyo F-term in Sony Corporation (reference) 3K007 AB02 AB03 AB04 BA06 BB00 CA01 CA05 CB01 DA00 DB03 EB00 FA01 FA03

Claims (8)

[Claims] 1. An organic electroluminescent device in which an organic layer having a light emitting region is provided between an anode and a cathode, wherein the organic layer is represented by the following general formula (1) or the following general formula (3). An organic electroluminescent device comprising at least one kind of a distyryl compound as an organic light emitting material. Embedded image [However, in the general formula (1), R ¹ , R ² , R ³
And R ⁴ are the same or different groups, and are aryl groups represented by the following general formula (2). (However, in the general formula (2), R ¹³ , R ¹⁴ ,
R ¹⁵ , R ¹⁶ and R ¹⁷ are the same or different groups, and each is a hydrogen atom, or at least one of them is a saturated or unsaturated alkoxyl group, an alkyl group, an amino group or an alkylamino group. ), R ⁵ , R ⁶ , R ⁷ , R ⁸ ,
R ⁹ , R ¹⁰ , R ¹¹ and R ¹² are the same or different groups, and at least one of them is a cyano group, a nitro group or a halogen atom. ] [However, in the general formula (3), R ¹⁸ , R ¹⁹ ,
R ²⁰ , R ²¹ , R ²² , R ²³ , R ²⁴ and R ²⁵ are the same or different groups, and at least one of them is a cyano group, a nitro group or a halogen atom. ] 2. The organic layer has an organic laminated structure in which a hole transport layer and an electron transport layer are laminated, and the distyryl compound is used as a material for forming the hole transport layer. The organic electroluminescent device according to claim 1. 3. The organic layer has an organic laminated structure in which a hole transport layer and an electron transport layer are sequentially laminated, and the distyryl compound is used as a material for forming the electron transport layer. The organic electroluminescent device according to claim 1. 4. The organic layer has an organic laminated structure in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated, and the distyryl compound is used as a material for forming the light emitting layer. The organic electroluminescent device according to claim 1. 5. An organic electroluminescent device in which an organic layer having a light emitting region is provided between an anode and a cathode, wherein the organic layer has the following structural formula (4) -1, (4) -2, (4) )-
3, (4) -4, (4) -5, (4) -6 or (4)-
An organic electroluminescent device, wherein at least one of the distyryl compounds represented by 7 is contained as an organic light emitting material. Embedded image 6. The organic layer has an organic laminated structure in which a hole transport layer and an electron transport layer are laminated, and the distyryl compound is used as a material for forming the hole transport layer. An organic electroluminescent device according to claim 5. 7. The organic layer has an organic laminated structure in which a hole transport layer and an electron transport layer are sequentially laminated, and the distyryl compound is used as a material for forming the electron transport layer. An organic electroluminescent device according to claim 5. 8. The organic layer has an organic laminated structure in which a hole transport layer, a light emitting layer, and an electron transport layer are laminated, and the distyryl compound is used as a material for forming the light emitting layer. An organic electroluminescent device according to claim 5.