JP2000164363A - Organic electroluminescent element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an element having high emitted light luminance and a long lifetime by including the aromatic cyclic compound composed of the aromatic ring, which does not include N atom, and the reducing dopant in an electron injection area, setting the electron affinity of the electron injection area at a specified value, and including a specified styryl group in an organic luminescent area. SOLUTION: Electron affinity of an electron injection area is set at 1.8-3.6 eV, and the aromatic ring compound having at least one styryl group expressed with formulas I-III is included. In the formula I, Ar1 means an aromatic group having 6-40 carbon, Ar2-Ar4 respectively mean H or an aromatic group having 6-40 carbon, and one of the Ar1-Ar4 means an aromatic group, and the number of condensation (n) means an integer 1-6. In the formula II, Ar5 means an aromatic group having 6-40 carbon, Ar6, Ar7 respectively mean H or an aromatic group having 6-40 carbon, and at least one of Ar5-Ar7 is substituted with a styryl group, and the number of condensation (m) means an integer 1-6. In the formula III, Ar8, Ar14 mean an aromatic group having 6-40 carbon, Ar9-Ar13 respectively mean H or an aromatic group having 6-40 carbon, and at least one of the Ar8-Ar14 is substituted with a styryl group, and the number of condensation (p)-(s) respectively means 0 or 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence device (hereinafter, also referred to as "organic EL device"). More specifically, the present invention relates to an organic EL device suitable for use in consumer and industrial display devices (displays) or light sources of printer heads.

[0002]

2. Description of the Related Art An example of a conventional organic EL device is disclosed in Document 1:
It is disclosed in "JP-A-4-297076".
As shown in FIG. 10, the organic EL element 60 disclosed in Document 1 has three organic films 52, 54 and 56 interposed between a cathode layer 58 and an anode layer 50 as a transparent electrode. It constitutes a film stack. Of the three organic films, the first organic film 52 in contact with the cathode layer 58 is doped with a donor impurity, while the second organic film 54 in contact with the anode layer 50 has an acceptor impurity. Is doped. As the acceptor impurities, a CN-substituted compound and a quinone compound (for example, chloranil) are used. The third organic film sandwiched between the first organic film 52 and the second organic film serves as the light emitting layer 56. The light emitting layer 56 includes first and second organic films 52 and 54.
Confine the carrier. Therefore, the organic EL element 60 can obtain high light emission luminance (light emission efficiency) at a low drive voltage.

Another example of the conventional organic EL device is as follows.
Reference 2: "Digest of Technical"
Papers (Digest of Technical Papers) SID '97, p. 775, 1997 ". In the organic EL device disclosed in Document 2, the electron transport layer is made of a material obtained by adding Li to an 8-hydroxyquinoline Al complex (Alq complex).

[0004]

[0005] However, Document 1
In the organic EL device disclosed in the above, the CN-substituted compound or quinone compound used as an acceptor impurity has excellent electron-transporting properties, but has strong acceptor properties,
The electron affinity is a high value of 3.7 eV or more. Therefore, these acceptor impurities tend to react with a compound constituting the light emitting region to easily form a charge transfer complex or an exciplex. For this reason, there have been problems that the emission luminance of the organic EL element is reduced and the life is short.

In the organic EL device disclosed in Document 1, the difference between the electron affinity of the first organic layer doped with the donor impurity and the electron affinity of the light emitting region is 0.5 e.
The value is as large as V or more. For this reason, the light emitting area and the first
Is a blocking junction, and electron injection from the first organic layer to the light-emitting region is likely to be defective. As a result, the luminous efficiency of the organic EL element is further reduced.

On the other hand, also in the organic EL device disclosed in Document 2, the Alq complex contains a nitrogen atom,
Although the electron transport layer composed of the lq complex and the Li compound has excellent electron transport properties, it tends to easily form a charge transfer complex or exciplex and has a high driving voltage. Therefore, similarly to the organic EL element disclosed in Document 1, there is a problem that the emission luminance of the organic EL element is easily reduced and the life is short.

Therefore, the inventors of the present invention diligently studied the above problem, and found that in the electron injection region, an aromatic ring compound containing an aromatic ring containing no nitrogen atom was used, or an aromatic ring compound containing a nitrogen atom was used. Even when an aromatic ring compound composed of an aromatic ring is used, by using a specific reducing dopant in combination, the driving voltage of the organic EL element can be reduced, and the emission luminance can be improved. It has been found that the life can be extended. That is, according to the present invention, the driving voltage is low, the emission luminance is high, and the organic E has a long life.
An object is to provide an L element.

[0008]

According to an aspect of the organic EL device of the present invention (first invention), the organic EL device has a structure in which at least an anode layer, a light emitting region, an electron injection region, and a cathode layer are sequentially laminated, The electron injecting region contains an aromatic ring compound containing no nitrogen atom and a reducing dopant, the electron injecting region has an electron affinity within a range of 1.8 to 3.6 eV, and an organic compound. The following general formulas (1) to (3)
Characterized by containing an aromatic ring compound having any one styryl group represented by

[0009]

Embedded image

[In the general formula (1), Ar ¹ has 6 carbon atoms.
To 40 aromatic groups, Ar ² , Ar ³ , and Ar ⁴
Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is 1 to 6 Is an integer. ]

[0011]

Embedded image

[In the general formula (2), Ar ⁵ has 6 carbon atoms.
An 40 aromatic group, Ar ⁶ and Ar ^7, hydrogen atom or carbon atoms each an aromatic group having 6 to 40,
At least one of Ar ⁵ , Ar ⁶ and Ar ⁷ is substituted with a styryl group, and the condensed number m is an integer of 1 to 6. ]

[0013]

Embedded image

[In the general formula (3), Ar ⁸ and Ar
¹⁴ is an aromatic group having 6 to 40 carbon atoms, and Ar ^{9 to} A
r ¹³ is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are It is 0 or 1, respectively. ]

By using an aromatic ring compound comprising an aromatic ring containing no nitrogen atom in the electron injection region, excellent electron injection properties can be obtained, and at the same time, the reaction with the constituent materials of the adjacent light emitting region can be achieved. Can be suppressed. That is, the aromatic ring compound composed of an aromatic ring containing no nitrogen atom is composed of an aromatic ring composed of carbon and hydrogen, or an aromatic ring composed of carbon, hydrogen and oxygen. Electric suction group (for example, -C
It does not contain nitrogen-containing groups such as N group, -NO ₂ group, amide group and imide group. Therefore, generation of a charge transfer complex or exciplex having low luminous efficiency at the interface between the electron injection region and the light emitting region can be efficiently suppressed. However, there is no problem that a nitrogen atom is contained in a portion other than the aromatic ring and the electro-attractive group. For example, it is rather preferable to bond the aromatic ring via the nitrogen atom.

Further, by containing a reducing dopant together with an aromatic ring compound containing an aromatic ring not containing a nitrogen atom in the electron injection region, the aromatic ring of the aromatic compound containing no nitrogen atom can be efficiently converted. To an anionic state. Therefore, it is possible to more effectively prevent the generation of a charge transfer complex or exciplex having low luminous efficiency, and to improve the luminous luminance and extend the life of the organic EL element.

Furthermore, by limiting the electron affinity of the electron injection region to such a value, excellent electron injection properties can be obtained, and at the interface between the electron injection region and the light emitting region,
Generation of a charge transfer complex or exciplex can be suppressed, and further, generation of a blocking junction between an electron injection region and a light emission region can be suppressed. Therefore, it is possible to further improve the emission luminance and extend the life of the organic EL element.

Further, in constituting the organic EL device of the first invention, the styryl group in the styryl group-containing aromatic ring compound is preferably a styryl group represented by the following general formula (4).

[0019]

Embedded image

[In the general formula (4), Ar ¹⁵ Ar ¹⁶ and Ar ¹⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. ]

Further, in constituting the organic EL device of the first invention, it is preferable to set the glass transition point of the electron injection region to a value of 100 ° C. or more. By setting the glass transition point of the electron injection region to 100 ° C. or higher, the organic EL
The heat-resistant temperature of the element can be, for example, 85 ° C. or higher. Therefore, the tendency of the electron injection region to be destroyed in a short time due to Joule heat due to current injection from the current injection layer to the light emission region during light emission is reduced, and the life of the organic EL element can be further extended.

In constructing the organic EL device of the first invention, the aromatic ring in the aromatic ring compound has an anthracene, fluorene, perylene, pyrene, phenanthrene, chrysene, tetracene, rubrene, terphenylene, quarterphenylene, It is preferably at least one aromatic ring selected from the group consisting of sexiphenylene and triphenylene.

In constituting the organic EL device of the first invention, the aromatic ring in the aromatic ring compound is substituted with a styryl-substituted aromatic ring, a distyryl-substituted aromatic ring and a tristyryl-substituted aromatic ring. It is preferably at least one aromatic ring selected from the group consisting of aromatic rings.

In constituting the organic EL device of the first invention, the reducing dopant is an alkali metal, an alkaline earth metal, a rare earth metal, an oxide of an alkali metal, a halide of an alkali metal, or an alkaline earth metal. , An oxide of an alkaline earth metal, an oxide of a rare earth metal, or a halide of a rare earth metal.

In constituting the organic EL device of the first invention, the work function of the reducing dopant is 3.0 eV.
The following values are preferred. By using a reducing dopant whose work function value is equal to or less than a specific value in this manner, the reducing ability is sufficiently exhibited, the driving voltage is reduced,
It is possible to improve the emission luminance and extend the life.

In constituting the organic EL device of the first invention, the reducing dopant is Li, Na, K, R
It is preferably at least one alkali metal selected from the group consisting of b and Cs. These reducing dopants have a particularly high reducing ability, and when added in a relatively small amount, the emission luminance of the organic EL device can be improved, for example, a high value of 500 cd / m ² or more (7 V applied condition) can be obtained. Life extension, for example, a half life of 1000 hours or more can be obtained.

In configuring the organic EL device of the first invention, the energy gap of the electron injection region is set to 2.
The value is preferably 7 eV or more. Thus, by increasing the energy gap of the electron injection region,
It is possible to effectively prevent holes from moving to the electron injection region. Therefore, it is possible to prevent the electron injection region itself from emitting light.

Further, in constituting the organic EL device of the first invention, the addition ratio between the aromatic ring compound and the reducing dopant is set to a value within the range of 1:20 to 20: 1 (molar ratio). Is preferred. When the addition ratio of the aromatic ring compound and the reducing dopant is out of these ranges, the emission luminance of the organic EL device tends to decrease and the life tends to be shortened.

In constituting the organic EL device of the first invention, it is preferable that the light emitting region and the electron injection region contain the same kind of aromatic ring compound containing no nitrogen atom. By containing the same kind of aromatic ring compound in both regions, excellent adhesion is obtained, and electrons can be smoothly moved from the electron injection region to the light emission region.
Mechanical strength can be improved.

Further, in forming the organic EL device of the first invention, or in forming the organic EL device of the second invention described later, the space between the cathode layer and the electron injection region and the space between the anode layer and the light emitting region are formed. It is preferable to provide an interface layer during or any one of them. By providing the interface layer in this manner, the values of the emission luminance and the half-life can be significantly improved.

According to another aspect of the organic EL device of the present invention (second invention), at least the anode layer, the light emitting region,
It has a structure in which an electron injection region and a cathode layer are sequentially laminated. The electron injection region contains an electron transporting compound and a reducing dopant having a work function of 2.9 eV or less. Electron affinity of 1.8 to 3.6 eV
And the organic light-emitting region contains an aromatic ring compound having any one styryl group represented by the following general formulas (1) to (3).

[0032]

Embedded image

[In the general formula (1), Ar ¹ has 6 carbon atoms.
To 40 aromatic groups, Ar ² , Ar ³ , and Ar ⁴
Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is 1 to 6 Is an integer. ]

[0034]

Embedded image

[In the general formula (2), Ar ⁵ has 6 carbon atoms.
An 40 aromatic group, Ar ⁶ and Ar ^7, hydrogen atom or carbon atoms each an aromatic group having 6 to 40,
At least one of Ar ⁵ , Ar ⁶ and Ar ⁷ is substituted with a styryl group, and the condensed number m is an integer of 1 to 6. ]

[0036]

Embedded image

[In the general formula (3), Ar ⁸ and Ar
¹⁴ is an aromatic group having 6 to 40 carbon atoms, and Ar ^{9 to} A
r ¹³ is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are It is 0 or 1, respectively. ]

As described above, by including a reducing dopant having a specific value as a work function in the electron injection region, even when the electron transporting compound is oxidized, it can be efficiently reduced to an anion state. it can. Therefore,
By effectively preventing the generation of the charge transfer complex or the exciplex, it is possible to reduce the driving voltage, improve the emission luminance, and extend the life of the organic EL element. That is, in the second invention, unlike the first invention, the electron-transporting compound contains a nitrogen-containing group such as a nitrogen-containing aromatic ring or an electron-withdrawing group because the reducing ability of the reducing dopant is high. Also, there is an advantage that the reaction with the constituent material in the light emitting region can be suppressed.

By limiting the electron affinity of the electron injection region in this way, it is possible to suppress the generation of a charge transfer complex or exciplex at the interface between the electron injection region and the light emitting region, and to reduce the electron injection region. The occurrence of blocking junction with the light emitting region can also be suppressed. Therefore, it is possible to further improve the emission luminance and extend the life of the organic EL element.

In constituting the organic EL device of the second invention, the styryl group in the aromatic ring compound is preferably a styryl group represented by the following general formula (4).

[0041]

Embedded image

[In the general formula (4), Ar ¹⁵ Ar ¹⁶ and Ar ¹⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. ]

In constituting the organic EL device of the second invention, Na, K, Rb, C
It is preferably at least one alkali metal or alkaline earth metal selected from the group consisting of s, Ca, Sr and Ba. These reducing dopants are L
i has a higher reducing ability than i, and the addition of a relatively small amount improves the emission luminance of the organic EL element, for example, a voltage of 7 V
Under application conditions, a high value of 500 cd / m ² or more can be obtained, and a long life, for example, a half life of 1000 hours or more can be obtained.

In constituting the organic EL device of the second invention, the electron transporting compound preferably contains a nitrogen-containing heterocyclic compound. This is because the nitrogen-containing heterocyclic compound is excellent in electron transportability and further improves electron injectability.

In constituting the organic EL device of the second invention, the nitrogen-containing heterocyclic compound is selected from the group consisting of a nitrogen-containing complex, a quinoxaline derivative, a quinoline derivative, an oxadiazole derivative, a thiadiazole derivative and a triazole derivative. Preferably, at least one compound is used.

Further, in constituting the organic EL device of the second invention, the addition ratio of the electron transporting compound and the reducing dopant is set to a value within the range of 1:20 to 20: 1 (molar ratio). Is preferred. When the addition ratio of the electron transporting compound and the reducing dopant is out of these ranges, the organic E
The light emission luminance of the L element tends to decrease and the life tends to be shortened.

Further, in constituting the organic EL device of the second invention, it is preferable to set the glass transition point of the electron injection region to a value of 100 ° C. or higher. By limiting the glass transition point in the electron injection region in this way, the heat-resistant temperature of the organic EL element can be increased, and the life of the organic EL element can be extended.

Further, in constituting the organic EL device of the second invention, it is preferable to use the same kind of electron transporting compound in the light emitting region and the electron injection region. By containing the same type of electron transporting compound in both regions, excellent adhesion can be obtained, electrons can smoothly move from the electron injection region to the light emitting region, and the mechanical strength is improved. Can be.

[0049]

Embodiments of the present invention will be described below with reference to the drawings. It should be noted that the drawings to be referred to show the size of each component so that the present invention can be understood,
It merely shows the shape and arrangement.
Therefore, the present invention is not limited only to the illustrated example. In the drawings, hatching representing a cross section may be omitted.

First Embodiment First, a first embodiment of the organic EL device of the present invention will be described with reference to FIG. FIG. 1 is a cross-sectional view of an organic EL device 100 having a structure in which an anode layer 10, a light emitting region 12, an electron injection region 14, and a cathode layer 16 are sequentially laminated on a substrate (not shown). It represents that it is. Hereinafter, the electron injection region 14 and the light emission region 12 which are characteristic portions of the first embodiment will be mainly described. Therefore, other components, for example, the configurations and manufacturing methods of the anode layer 10 and the cathode layer 16 and the like will be briefly described, and the portions not mentioned will be configurations generally known in the field of organic EL devices. And a manufacturing method can be adopted.

(1) Electron Injection Zone (Aromatic Ring Compound) The electron injection zone in the first embodiment is an aromatic ring compound composed of an aromatic ring containing no nitrogen atom (when simply referred to as an aromatic ring compound). That is, a compound containing an aromatic ring composed of carbon (C) and hydrogen (H) or a compound containing an aromatic ring composed of carbon (C), hydrogen (H) and oxygen (O). Contains. However, other than the aromatic ring, a nitrogen atom may be contained, and it is rather preferable that aromatic rings not containing a nitrogen atom are bonded to each other by, for example, a nitrogen atom. Further, the compound of the aromatic ring composed of carbon and hydrogen and the compound of the aromatic ring composed of carbon, hydrogen and oxygen may be used alone or in combination.

The preferred aromatic ring in the aromatic ring compound not containing a nitrogen atom includes, for example, anthracene, fluorene, perylene, pyrene, phenanthrene, chrysene, tetracene, rubrene, terphenylene, quarterphenylene, sexifphenylene, Examples include at least one aromatic ring selected from the group consisting of triphenylene, picene, coronel, diphenylanthracene, benz [a] anthracene, and binaphthalene. Further, it is more preferable that the aromatic ring compound containing no nitrogen atom contains an aromatic ring obtained by condensing three or more of these aromatic rings, for example, anthracene. By having an aromatic ring in which three or more rings are condensed, electron mobility is increased, and
The light emission luminance of the element can be improved, and high-speed response can be improved.

Further, the aromatic ring compound containing no nitrogen atom more preferably has a styryl group-substituted aromatic ring, a distyryl group-substituted aromatic ring or a tristyryl group-substituted aromatic ring. Thus, styryl group substitution (including distyryl group substitution and tristyryl group substitution).
Hereinafter, the same applies. ), The light emission luminance and the life of the organic EL element can be further improved.

Here, examples of the aromatic ring compound containing a styryl group-substituted group include the same aromatic ring compounds as those represented by formulas (1) to (3) used in the emission region. Group ring compounds. Further, the styryl group in the aromatic ring compound is preferably a styryl group represented by the general formula (4), similarly to the aromatic ring compound used in the emission region.

As the aromatic ring compound containing a distyryl-substituted group, for example, a compound represented by the following general formula (5) is preferably used. Ar ¹⁸ -L-Ar ¹⁹ (5) In the above formula (5), L is an arylene group having 6 to 30 carbon atoms. As the arylene group, for example,
Phenylene, biphenylene, naphthylene, and anthracendil are preferred, and the structure of the arylene group is preferably a single crystal. As Ar ¹⁸ and Ar ¹⁹ , for example, diphenylanthracene,
Diphenylpyrene is preferred.

The formulas (1) to (3) or (5)
Is preferably further substituted with a substituent. Such substituents include, for example,
An alkyl group having 1 to 30 carbon atoms, an alkyloxy group having 1 to 30 carbon atoms, an arylalkyl group having 6 to 30 carbon atoms, a diarylamino group, an N-alkylcarbazolyl group, or N-phenylcarbazolyl Groups are preferred. By substitution with these substituents, generation of a complex having low luminous efficiency can be efficiently suppressed.

(Reducing Dopant) The electron injection region in the first embodiment is characterized in that it contains a reducing dopant. Here, the reducing dopant is defined as a substance that can reduce an aromatic ring compound when it is oxidized. Therefore, the reducing dopant is not particularly limited as long as it has a certain reducing property, specifically, an alkali metal, an alkaline earth metal,
Rare earth metal, alkali metal oxide, alkali metal halide, alkaline earth metal oxide, alkaline earth metal halide, rare earth metal oxide or rare earth metal halide It is preferably one substance.

Preferred alkali metals include, for example,
Li (lithium, work function: 2.93 eV), Na (sodium, work function: 2.36 eV), K (potassium,
Work function: 2.3 eV), Rb (rubidium, work function: 2.16 eV) and Cs (cesium, work function:
1.95 eV). The values of the work functions in parentheses are described in the Chemical Handbook (Basic Edition II, P493, edited by The Chemical Society of Japan), and the same applies hereinafter. Also,
Preferred alkaline earth metals include, for example, Ca (calcium, work function: 2.9 eV), Mg (magnesium, work function: 3.66 eV), Ba (barium, work function: 2.52 eV), and Sr (strontium) ,
Work function: 2.0 to 2.5 eV). In addition,
The value of the work function of strontium is based on the Physics of Semiconductor device (NY Wilo 19
69, p. 366). Preferred rare earth metals include, for example, Yb (ytterbium, work function: 2.6 eV), Eu (eurobium,
Work function: 2.5 eV), Gd (gadnium, work function: 3.1 eV) and En (erbium, work function:
2.5 eV).

Preferred alkali metal oxides include, for example, Li ₂ O, LiO and NaO. Preferred alkaline earth metal oxides include:
For example, CaO, BaO, SrO, BeO and MgO
Is raised.

Preferred alkali metal halides include, for example, fluorides such as LiF, NaF and KF, as well as LiCl, KCl and NaCl.
Is mentioned. Preferred alkaline earth metal halides include, for example, CaF ₂ , BaF ₂ , SrF
_2, fluorides such as MgF ₂ and BeF _2, and halides other than fluorides.

As a preferable reducing dopant,
An aromatic compound coordinated with an alkali metal is also included. The aromatic compound coordinated with the alkali metal is represented by, for example, the following general formula (6). A ⁺ Ar ^20- (6) where A in the general formula (6) represents an alkali metal.
Ar ²⁰ is an aromatic compound having 10 to 40 carbon atoms. Examples of the aromatic compound represented by the formula (6) include anthracene, naphthalene, diphenylanthracene, terphenyl, quarterphenyl, kinkphenyl, sexiphenyl and derivatives thereof.

Next, the amount of the reducing dopant added in the electron injection region will be described. The amount of the reducing dopant to be added is preferably set to a value within the range of 0.01 to 50% by weight when the entire material constituting the electron injection region is 100% by weight. When the amount of the reducing dopant added is 0.0
When the content is less than 1% by weight, the emission luminance of the organic EL element tends to decrease and the life tends to be shortened. On the other hand, when the addition amount of the reducing dopant exceeds 50% by weight, on the contrary, the emission luminance tends to decrease and the life tends to be shortened. Therefore, it is more preferable to set the amount of the reducing dopant to a value in the range of 0.2 to 20% by weight from the viewpoint that the balance between the emission luminance and the life becomes better.

Further, with respect to the addition amount of the reducing dopant, it is preferable that the addition ratio between the aromatic ring compound and the reducing dopant is a value within a range of 1:20 to 20: 1 (molar ratio). When the addition ratio of the electron transporting compound and the reducing dopant is out of these ranges, the emission luminance of the organic EL device tends to decrease and the life tends to be shortened. Therefore, the addition ratio of the aromatic ring compound to the reducing dopant is more preferably set to a value within the range of 1:10 to 10: 1 (molar ratio), and a value within the range of 1: 5 to 5: 1. More preferably,

(Electron Affinity) The electron affinity of the electron injection region in the first embodiment is preferably set to a value within the range of 1.8 to 3.6 eV. The value of electron affinity is 1.8
If it is less than eV, the electron injecting property tends to decrease, leading to an increase in driving voltage and a decrease in luminous efficiency. On the other hand, when the value of electron affinity exceeds 3.6 eV, a complex having low luminous efficiency is generated. Thus, the occurrence of blocking junction can be suppressed efficiently. Therefore, the electron affinity in the electron injection region is more preferably set to a value within the range of 1.9 to 3.0 eV, and even more preferably set to a value within the range of 2.0 to 2.5 eV.

The difference in electron affinity between the electron injection region and the light emission region is preferably set to a value of 1.2 eV or less.
More preferably, the value is 5 eV or less. The smaller the difference in electron affinity, the easier the electron injection from the electron injection region to the light emission region, and a high-speed response organic EL device can be obtained.

(Glass Transition Point) The glass transition point (glass transition temperature) of the electron injection region in the first embodiment is
The value is preferably 100 ° C. or more, more preferably a value in the range of 105 to 200 ° C.
By limiting the glass transition point in the electron injection region in this way, the heat-resistant temperature of the organic EL element 100 can be easily set to 85 ° C. or higher. Therefore, even when a current is injected from the current injection layer into the light emitting region during light emission and Joule heat is generated, the tendency of the electron injection region to be destroyed in a short time is reduced, and the life of the organic EL element is extended. Can be. The glass transition point of the electron injection region is determined by the differential thermal scanning calorimeter (DSC) for the components constituting the electron injection region.
Can be determined as a specific heat change point from a specific heat change curve obtained when heating is performed in a nitrogen gas stream at a rate of temperature increase of 10 ° C./min. This point is the same in other embodiments and examples.

(Energy Gap) The energy gap (band gap energy) of the electron injection region in the first embodiment is preferably set to a value of 2.7 eV or more, and more preferably to a value of 3.0 eV or more. . As described above, if the value of the energy gap is set to a predetermined value or more, for example, 2.7 eV or more, holes are less likely to move beyond the light emitting region to the electron injection region. Therefore, the efficiency of recombination of holes and electrons is improved, the light emission luminance of the organic EL element is increased, and light emission in the electron injection region itself can be avoided.

(Structure of Electron Injection Area) The structure of the electron injection area in the first embodiment is not particularly limited and is not limited to a single-layer structure. For example, it has a two-layer structure or a three-layer structure. May be. Further, the thickness of the electron injection region is not particularly limited.
Preferably, the value is in the range of nm to 1 μm,
More preferably, the value is in the range of 0 nm.

(Method of Forming Electron Injection Area) Next, a method of forming the electron injection area will be described. The method for forming the electron injection region is not particularly limited as long as it can be formed as a thin film layer having a uniform thickness. For example, a known method such as an evaporation method, a spin coating method, a casting method, and an LB method may be used. Can be applied. Note that it is preferable that the aromatic ring compound containing no nitrogen atom and the reducing dopant be co-evaporated, and this evaporation method will be described in detail in the sixth embodiment.

Further, it is preferable that the method of forming the electron injection region and the method of forming the light emitting region are the same. For example, when the light emitting region is formed by a vapor deposition method, it is preferable that the electron injection region is also formed by a vapor deposition method. When the film is formed by the same method as described above, the electron injection region and the light emitting region can be continuously formed, which is advantageous in simplifying the equipment and shortening the settlement time. Further, since the chances of oxidizing the electron injection region and the light emitting region are reduced, the light emission luminance of the organic EL element can be improved.

(2) Light-Emitting Region (Constituent Material) The organic light-emitting material used as a constituent material of the light-emitting region preferably has the following three functions. (A) Charge injection function: a function of injecting holes from an anode or a hole injection layer when an electric field is applied, and a function of injecting electrons from a cathode layer or an electron injection region. (B) Transport function: injection (C) Light-emitting function: a function of providing a field for recombination of electrons and holes and linking them to light emission, provided that the above (a) to (c) It is not always necessary to have all of the functions together. For example, some of the materials having a hole injection / transport property larger than the electron injection / transport property are suitable as organic light emitting materials. One of the objects of the present invention is to promote the transfer of electrons to the light emitting region and reduce the voltage.

Accordingly, the present invention is characterized in that an aromatic ring compound having a styryl group represented by the following general formulas (1) to (3) is used in the light emitting region. In addition,
As the styryl group, a styryl group represented by the above general formula (4) is preferable.

[0073]

Embedded image

[In the general formula (1), Ar ¹ has 6 carbon atoms.
To 40 aromatic groups, Ar ² , Ar ³ , and Ar ⁴
Is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is 1 to 6 Is an integer. ]

[0075]

Embedded image

[In the general formula (2), Ar ⁵ has 6 carbon atoms.
An 40 aromatic group, Ar ⁶ and Ar ^7, hydrogen atom or carbon atoms each an aromatic group having 6 to 40,
At least one of Ar ⁵ , Ar ⁶ and Ar ⁷ is substituted with a styryl group, and the condensed number m is an integer of 1 to 6. ]

[0077]

Embedded image

[In the general formula (3), Ar ⁸ and Ar
¹⁴ is an aromatic group having 6 to 40 carbon atoms, and Ar ^{9 to} A
r ¹³ is a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, at least one of Ar ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are It is 0 or 1, respectively. ]

Here, among the aromatic groups having 6 to 40 carbon atoms, preferred aryl groups having 5 to 40 nuclear atoms include:
Phenyl, naphthyl, anthranil, phenanthryl,
Pyrenyl, coronyl, biphenyl, terphenyl, pyrrolyl, furanyl, thiophenyl, benzothiophenyl, oxadiazolyl, diphenylanthranyl, indolyl, carbazolyl, pyridyl, benzoquinolyl and the like. Preferred arylene groups having 5 to 40 nuclear atoms include phenylene, naphthylene, anthranylene, phenanthrylene, pyrenylene, colonylene, biphenylene, terphenylene, pyrrolylene, furanylene, thiophenylene, benzothiophenylene, oxadiazolylene, and diphenylanthranylene. , Indolylene, carbazolylene, pyridylene, benzoquinolylene and the like. The aromatic group having 6 to 40 carbon atoms is
It may be further substituted with a substituent, and as a preferable substituent, an alkyl group having 1 to 6 carbon atoms (ethyl group,
A methyl group, an i-propyl group, an n-propyl group, an s-butyl group, a t-butyl group, a pentyl group, a hexyl group, a cyclopentyl group, a cyclohexyl group, etc.), an alkoxy group having 1 to 6 carbon atoms (ethoxy group, methoxy group) Group, i-propoxy group, n-propoxy group, s-butoxy group, t-butoxy group, pentoxy group, hexyloxy group, cyclopentoxy group, cyclohexyloxy group, etc.), 5 to 40 nuclear atoms
An aryl group, an amino group substituted with an aryl group having 5 to 40 nuclear atoms, an ester group having an aryl group having 5 to 40 nuclear atoms, an ester group having an alkyl group having 1 to 6 carbon atoms, a cyano group, Examples include a nitro group and a halogen atom. Therefore, specific examples of the aromatic ring compound having a styryl group represented by the general formula (1) include the following aromatic ring compounds.

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[0081]

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Further, specific examples of the aromatic ring compound having a styryl group represented by the general formula (2) include the following aromatic ring compounds.

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Further, specific examples of the aromatic ring compound having a styryl group represented by the general formula (3) include the following aromatic ring compounds.

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[0101]

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Further, a fluorescent brightener such as a benzothiazole type, a benzimidazole type, a benzoxazole type, or a metal complex having a styrylbenzene compound or an 8-quinolinol derivative as a ligand may be used in the light emitting region. preferable. Also, an organic light-emitting material having a distyrylarylene skeleton,
For example, 4,4'-bis (2,2-diphenylvinyl) biphenyl) or the like is used as a host, and the host is used in combination with a strong fluorescent dye ranging from blue to red, for example, a coumarin-based dye or a fluorescent dye similar to the host. It is also preferred to do so.

Also, excellent adhesion can be obtained, electrons can smoothly move from the electron injection region to the light emission region, and
From the viewpoint that the mechanical strength can be improved, the constituent material of the light emitting region and the constituent material of the electron injection region are partially matched, and the same type of aromatic ring compound containing no nitrogen atom is used in both regions. Is preferred. That is, it is preferable to use the aromatic ring compounds represented by the general formulas (1) to (3) in the light emitting region and the electron injection region, respectively. In the light emitting region and the electron injection region, the same kind of aromatic ring compound is preferably 50% by weight or more, and more preferably 60% by weight or more.

(Forming Method) Next, a method of forming a light emitting area will be described. For example, evaporation method, spin coating method,
Known methods such as a casting method and an LB method can be applied. In addition, as described above, the electron injection region and the light emitting region are preferably formed by the same method. For example, when the electron injection region is formed by a vapor deposition method, the light emitting region is also formed by the vapor deposition method. Is preferred.

The light emitting region is a thin film formed by deposition from a material compound in a gaseous phase or a film formed by solidification from a material compound in a solution or liquid phase.
It is preferable to use a molecular deposition film. Usually, this molecular deposition film can be distinguished from a thin film (molecule accumulation film) formed by the LB method by a difference in an aggregated structure or a higher-order structure and a functional difference caused by the difference. Furthermore, a light emitting region can also be formed by dissolving a binder such as a resin and an organic light emitting material in a solvent to form a solution, and then thinning the solution by spin coating or the like.

(Film Thickness of Light Emitting Region) The thickness of the light emitting region thus formed is not particularly limited and can be appropriately selected depending on the situation. However, the film thickness is in the range of 5 nm to 5 μm. Preferably, there is. When the film thickness in the light emitting region is less than 5 nm, the light emission luminance tends to decrease. On the other hand, when the film thickness in the light emitting region exceeds 5 μm, the value of the applied voltage tends to increase. Therefore, the film thickness of the light emitting region is 10 nm to
More preferably, the value is within a range of 3 μm.
More preferably, the value is in the range of m to 1 μm.

(3) Electrode (Anode Layer) As the anode layer, it is preferable to use a metal, an alloy, an electrically conductive compound or a mixture thereof having a large work function (for example, 4.0 eV or more). Specifically, one kind of indium tin oxide (ITO), indium copper, tin, zinc oxide, gold, platinum, palladium and the like can be used alone or in combination of two or more kinds. The thickness of the anode layer is not particularly limited, but is preferably in the range of 10 to 1000 nm, and more preferably in the range of 10 to 200 nm. Further, the anode layer is substantially transparent, and more specifically, has a light transmittance of 10% so that light emitted from the light emitting region can be effectively extracted to the outside.
It is preferable that the above values be used.

(Cathode Layer) On the other hand, for the cathode layer, it is preferable to use a metal, an alloy, an electrically conductive compound or a mixture thereof having a small work function (for example, less than 4.0 eV). Specifically, one kind of magnesium, aluminum, indium, lithium, sodium, silver, etc. is used alone,
Alternatively, two or more kinds can be used in combination.
The thickness of the cathode layer is not particularly limited, either.
Preferably, the value is in the range of 0 to 1000 nm.
More preferably, the value is in the range of 0 to 200 nm.

(4) Others Although not shown in FIG. 1, it is preferable to provide a sealing layer for preventing moisture and oxygen from entering the organic EL element so as to cover the entire element. Preferred materials for the sealing layer include a copolymer obtained by copolymerizing a monomer mixture containing tetrafluoroethylene and at least one comonomer; a fluorinated copolymer having a cyclic structure in the copolymer main chain. Polyethylene, polypropylene, polymethyl methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene or a copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene; water absorption with an absorption of 1% or more Water-absorbing substance having a water absorption of 0.1% or less; In, Sn, Pb, Au, Cu, Ag,
Metals such as Al, Ti, Ni; MgO, SiO, Si
O ₂ , GeO, NiO, CaO, BaO, Fe ₂ O ₃ , Y ₂
Metal oxides such as O ₃ and TiO ₂ ; MgF ₂ , LiF, Al
Metal fluorides such as F ₃ and CaF ₂ ; liquid fluorinated carbon such as perfluoroalkane, perfluoroamine, and perfluoropolyether; and a composition in which an adsorbent that adsorbs moisture and oxygen is dispersed in the liquid fluorinated carbon. Objects and the like.

In forming the sealing layer, a vacuum evaporation method, a spin coating method, a sputtering method, a casting method, an MBE (molecular beam epitaxy) method, a cluster ion beam evaporation method, an ion plating method, a plasma polymerization method ( RF excitation super-ion plating method), reactive sputtering method, plasma CVD method, laser CVD
Method, thermal CVD method, gas source CVD method, or the like can be appropriately employed.

<Second Embodiment> Next, the organic E of the present invention
A second embodiment of the L element will be described. Second
In the embodiment, as shown in FIG. 1, the anode layer 10, the light emitting region 12, the electron injection region 14, and the cathode layer 16 are formed on a substrate (not shown), as in the first embodiment. It has a structure in which layers are sequentially stacked. The second embodiment is different from the first embodiment in that the electron injection region 14 is composed of an electron transporting compound and a reducing dopant having a work function of 2.9 eV or less. I have. Therefore, in the following description, the electron transporting compound and the reducing dopant having a work function of 2.9 eV or less will be mainly described, and the other configurations are the same as those of the first embodiment and the organic EL device. A configuration generally known in the field can be adopted.

(Electron-Transporting Compound) In the electron-injecting region in the second embodiment, as the electron-transporting compound, as in the first embodiment, an aromatic ring compound containing no nitrogen atom, for example, a compound represented by the general formula ( Organic compounds containing a nitrogen-containing heterocyclic compound (which may be simply referred to as a nitrogen-containing heterocyclic compound in some cases) may be contained. It is also preferred to include. That is, unlike the first embodiment, the second embodiment has a function of transmitting electrons injected from the cathode to the light-emitting region, particularly because a highly reducing reducing dopant is used. Compounds can be widely used. Therefore, even when the nitrogen-containing heterocyclic compound is used as the electron transporting compound, it is possible to efficiently suppress the reaction with the material in the light emitting region. Further, in the electron injection region, the generation of the charge transfer complex or the exciplex can be effectively prevented, and the emission luminance and the life of the organic EL device can be improved.

The nitrogen-containing heterocyclic compound used in the electron injection region is defined as a compound having a heterocyclic ring having a nitrogen atom. Specific examples include a nitrogen-containing complex and a nitrogen-containing ring compound. A nitrogen-containing complex or a nitrogen-containing ring compound has a large electron affinity of 2.7 eV or more and a charge mobility of 1 eV.
This is because it is as fast as × 10 ⁶ cm ² / V · S or more. Among these, as a preferable nitrogen-containing complex, a metal complex having an 8-quinolinol derivative as a ligand, for example, a tris (8-quinolinol) Al complex represented by the following formula (27), a tris (5,7-dichloro- 8-quinolinol) Al complex, tris (5,7-dibromo-8-quinolinol) Al complex, tris (2-methyl-8-quinolinol) Al complex, tris (5-methyl-8-quinolinol) Al complex, tris ( 8-quinolinol) Zn complex, tris (8
-Quinolinol) In complex, tris (8-quinolinol) Mg complex, tris (8-quinolinol) Cu complex,
Tris (8-quinolinol) Ca complex, Tris (8-quinolinol) Sn complex, Tris (8-quinolinol) G
a complex and tris (8-quinolinol) Pb complex may be used alone or in combination of two or more.

[0114]

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Among the nitrogen-containing complexes, preferable phthalocyanine derivatives include, for example, metal-free phthalocyanine, Cu phthalocyanine, Li phthalocyanine, and Mg phthalocyanine.
One kind of phthalocyanine, Pb phthalocyanine, Ti phthalocyanine, Ga phthalocyanine, CuO phthalocyanine and the like may be used alone or in combination of two or more kinds.

Preferred nitrogen-containing ring compounds include:
At least one compound selected from the group consisting of oxadiazole derivatives, thiadiazole derivatives, triazole derivatives, quinoxaline derivatives and quinoline derivatives can be mentioned. Among these, representative examples of preferred oxadiazole derivatives are represented by the following formulas (28) and (2)
9), a typical example of a preferred thiadiazole derivative is shown in the following formula (30), a typical example of a preferred triazole derivative is shown in the following formula (31), a typical example of a quinoxaline derivative is shown in the following formula (32), and quinoline Representative examples of the derivative are shown in the following formula (33).

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Further, heterocyclic tetracarboxylic anhydrides such as anthrone derivatives, fluorenylimethane derivatives, carbodiimides and naphthalene perylenes;
It is also preferable to use an electron-transporting compound described as a light-emitting layer material in JP-A-9-194393.

(Reducing dopant having a work function of 2.9 eV or less) The electron injection region in the second embodiment contains a reducing dopant having a work function of 2.9 eV or less. Here, a reducing dopant having a work function of 2.9 eV or less is defined as a substance having a work function of 2.9 eV or less and capable of reducing a certain amount even when the electron transporting compound is oxidized. You. Therefore, the work function is 2.9.
eV or less and having a certain reducing property,
The reducing dopant exemplified in the first embodiment, for example, an alkali metal, an alkaline earth metal, a rare earth metal,
Alkali metal oxides, alkali metal halides,
At least one substance selected from the group consisting of alkaline earth metal oxides, alkaline earth metal halides, rare earth metal oxides, and rare earth metal halides can be suitably used.

More specifically, the work function is 2.9e
V is preferably not more than V.
(Work function: 2.36 eV), K (work function: 2.28)
eV), Rb (work function: 2.16 eV) and Cs
(Work function: 1.95 eV) at least one alkali metal selected from the group consisting of Ca and work function:
2.9 eV), Sr (work function: 2.0 to 2.5 e)
V), and at least one alkaline earth metal selected from the group consisting of Ba (work function: 2.52 eV).

Among these, more preferred reducing dopants are at least one alkali metal selected from the group consisting of K, Rb and Cs, more preferably Rb or Cs, most preferably Cs. These alkali metals have particularly high reducing ability, and by adding a relatively small amount to the electron injection region, the emission luminance and the life of the organic EL device can be improved.

Further, as a reducing dopant having a work function of 2.9 eV or less, a combination of two or more of these alkali metals is also preferable. In particular, a combination containing Cs, for example, Cs and Na, Cs and K, Cs And Rb or Cs
And a combination of Na and K. Cs
, The reducing ability can be efficiently exhibited, and the addition of the organic E
The light emission luminance and the life of the L element can be improved.

Next, the addition amount of the reducing dopant having a work function of 2.9 eV or less will be described. Similar to the first embodiment, the amount of the reducing dopant is preferably in the range of 0.1 to 50% by weight based on the material constituting the electron injection region, and 1 to 20% by weight. It is more preferable to set the value in the range of% by weight. The work function is 2.
With respect to the addition amount of the reducing dopant of 9 eV or less, the addition ratio of the electron transporting compound to the reducing dopant is 1: 2.
The value is preferably in the range of 0 to 20: 1 (molar ratio). When the addition ratio of the electron transporting compound and the reducing dopant is out of these ranges, the emission luminance of the organic EL device tends to decrease and the life tends to be shortened. Therefore, the addition ratio of the electron transporting compound and the reducing dopant is more preferably set to a value within a range of 1:10 to 10: 1 (molar ratio), and a value within a range of 1: 5 to 5: 1. More preferably, the most preferable is 1: 3 to
A value within a range of 3: 1.

(Electron Affinity) The electron affinity of the electron injection region in the second embodiment is preferably set to a value in the range of 1.8 to 3.6 eV, as in the first embodiment. The value is more preferably in the range of 9.9 to 3.0 eV, and even more preferably in the range of 2.0 to 2.5 eV. When the value of the electron affinity is out of these ranges, a complex having low luminous efficiency tends to be generated, and it tends to be difficult to suppress generation of a blocking junction. Note that the electron affinity of the electron injection region can be appropriately adjusted by changing the type or mixing ratio of the electron transporting compound and the reducing dopant constituting the electron injection region.

Also, in the electron injection region in the second embodiment, similarly to the first embodiment, the difference between the electron affinity in the electron injection region and the electron affinity in the light emission region is set to a value of 0.5 eV or less. It is more preferable to set the value to 0.2 eV or less. The smaller the difference in electron affinity, the easier the electron injection from the electron injection region to the light emission region,
This is because an organic EL element capable of high-speed response can be obtained.

(Glass Transition Point) The glass transition point of the electron injection region in the second embodiment is preferably set to a value of 100 ° C. or more, more preferably, as in the first embodiment. The value is in the range of 105 to 200 ° C.

<Third Embodiment> Next, a third embodiment of the present invention will be described with reference to FIG. FIG.
Is a cross-sectional view of the organic EL element 102 according to the third embodiment, and shows an anode layer 10, a hole injection / transport layer 18, a light emitting region 1;
2. It has a structure in which an electron injection region 14 and a cathode layer 16 are sequentially laminated. Then, the organic EL element 102
Has the same structure as the organic EL device 100 of the first and second embodiments except that a hole injection / transport layer 18 is inserted between the anode layer 10 and the light emitting region 12. are doing. Therefore, the following description is about the hole injection / transport layer 18 which is a characteristic part of the third embodiment, and the other components, for example, the electron injection region 14 and the like, are the first or second. The configuration can be the same as that of the embodiment.

The hole injection transport layer 1 according to the third embodiment
8 has a function of smoothly injecting holes substantially in the same manner as the hole injection layer, and also has a function of efficiently transporting injected holes. Therefore, by providing the hole injecting and transporting layer 18, the injection of holes and the movement to the light emitting region are facilitated, and a high-speed response of the organic EL element is possible.

Here, the hole injection transport layer 18 is formed of an organic material or an inorganic material. Preferred organic materials include, for example, diamine compounds, diamine-containing oligomers and thiophene-containing oligomers. Preferred inorganic materials include, for example, amorphous silicon (α-Si), α-SiC, microcrystal silicon (μC-Si), μC-SiC, II-
Group VI compounds, III-V compounds, amorphous carbon, crystalline carbon and diamond. Further, the hole transport layer 18 is not limited to a single layer structure, and may have, for example, a two-layer structure or a three-layer structure.
The thickness of 8 is not particularly limited, but is preferably, for example, a value in the range of 0.5 nm to 5 μm.

FIG. 5 shows a modification of the third embodiment. In the third embodiment, the hole injection transport layer 18
In the modification of the third embodiment, as shown in FIG. 5, the hole injection / transport layer 18 includes a hole transport layer 18b and a hole injection layer 18a. It is different in that it is. With such a configuration, the hole injection effect and the transport effect can be separately carried, the injection of the holes and the movement to the light emitting region become easier, and the high-speed response of the organic EL element 102a becomes possible.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described with reference to FIG. FIG.
Is a cross-sectional view of the organic EL element 104 according to the fourth embodiment, which includes an anode layer 10, a hole injection / transport layer 18, a light emitting region 1;
2, electron injection region 14, first interface layer 20, and cathode layer 1
6 are sequentially laminated.

This organic EL device has the same structure as the organic EL device 102 of the third embodiment except that a first interface layer 20 is inserted between the electron injection region 14 and the cathode layer 16. It has the same structure. Therefore, the following description is about the first interface layer, which is a characteristic part of the fourth embodiment, and other constituent parts are described below.
A configuration similar to the first to third embodiments or a configuration generally known in the field of organic EL elements can be used.

The first interface layer in the fourth embodiment is
It has a function to enhance electron injection properties. Therefore, by providing the first interface layer, injection of electrons and movement to the light-emitting region are facilitated, and high-speed response of the organic EL element is enabled. Here, for the first interface layer, it is preferable to use a material having an electron injecting property, for example, an alkali metal compound, an alkaline earth metal compound, an amorphous containing an alkali metal or a microcrystal containing an alkali metal. . More specifically, preferable alkali metal compounds include, for example, LiF, Li ₂ O, LiO
And LiCl. Preferred alkaline earth metal compounds include, for example, BaO, SrO, M
gO, MgF _2, SrCl _2, and the like. Also, the first
Is not limited to a single-layer structure, and may be, for example, a two-layer structure or structure. Further, the thickness of the first interface layer is not particularly limited.
Preferably, the value is in the range of m to 10 μm.

FIG. 6 shows a modification of the fourth embodiment. In the fourth embodiment, the hole injection transport layer 18
In contrast, in the modification of the fourth embodiment, as shown in FIG. 6, the hole injection transport layer 18 includes a hole transport layer 18b and a hole injection layer 18a. It is different in that it is. With such a configuration, the hole injection effect and the transport effect can be separately carried, the injection of the holes and the movement to the light emitting region become easier, and the high-speed response of the organic EL element 104a becomes possible.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described with reference to FIG. FIG.
Is a cross-sectional view of the organic EL element 106 according to the fifth embodiment, which includes an anode layer 10, a second interface layer 24, a hole injection / transport layer 18, a light emitting region 12, an electron injection region 14, and a cathode layer 1.
6 are sequentially laminated.

The organic EL device 106 according to the third embodiment is the same as the organic EL device according to the third embodiment except that a second interface layer 24 is inserted between the anode 16 and the hole injection transport layer 18. 1
02 has the same structure. Therefore, the following description is based on the anode 1 which is a characteristic part of the fourth embodiment.
6 and the second interface layer 24 provided between the hole injecting / transporting layer 18. Other components are the same as those in the first to fourth embodiments or the organic E
A configuration generally known in the field of the L element can be used.

Second Interface Layer 24 in Fifth Embodiment
Has a function of improving the hole injection property from the anode 16. Therefore, by providing the second interface layer, injection of holes and transfer to the light emitting region are facilitated, and the organic EL
A high-speed response of the device becomes possible.

Here, as the constituent material of the second interface layer, polyaniline, amorphous carbon, phthalocyanines and the like can be used. Further, the second interface layer is not limited to a single-layer structure, and may have, for example, a two-layer structure or structure. Further, the thickness of the second interface layer is not particularly limited, but is preferably, for example, a value in the range of 0.5 nm to 5 μm.

<Sixth Embodiment> Next, a sixth embodiment of the present invention will be described with reference to FIGS. Sixth
According to the embodiment, even if the electron injection region or the like has a large area, the composition ratio of the constituent materials is made uniform, the variation in the driving voltage of the organic EL element can be reduced, the life can be made uniform, and the space can be saved. An object of the present invention is to provide a method of manufacturing an organic EL device which is possible.

That is, using a vacuum evaporation apparatus 201 as shown in FIGS. 7 and 8 as an example, different evaporation materials are simultaneously evaporated from a plurality of evaporation sources 212A to 212F arranged opposite to the substrate 203 to form a film. In this method, a rotation axis 213A for rotating the substrate 203 is set on the substrate 203, and the deposition sources 212A to 212F are separated from the rotation axis 213A of the substrate 203, respectively. And the substrate 203
Is characterized in that vapor deposition is performed while rotating.

Here, the vacuum evaporation apparatus 201 shown in FIGS. 7 and 8 includes a vacuum chamber 210, a substrate holder 211 for fixing the substrate 203, which is installed in the upper portion of the vacuum chamber 210, It comprises a plurality (six) of evaporation sources 212A to 212F, which are arranged below the holder 211 and are opposed to each other, for filling an evaporation material. The inside of the vacuum chamber 210 can be maintained at a predetermined reduced pressure state by an exhaust means (not shown). In addition,
Although the number of vapor deposition sources is shown in the drawing as six, the number is not limited thereto, and may be five or less, or seven or more.

The substrate holder 211 is provided with a holding portion 212 for supporting the peripheral portion of the substrate 203, and is configured to hold the substrate 203 horizontally in the vacuum chamber 210. At the center of the upper surface of the substrate holder 211, a rotating shaft 213 for rotating (rotating) the substrate 203 is provided upright in the vertical direction. The rotating shaft 213 is connected to a motor 214 serving as a rotation disturbance unit.
4 rotates the substrate 203 held by the substrate holder 211 together with the substrate holder 211 into the rotating shaft 2.
13 rotates around the center of rotation. That is, at the center of the substrate 203, the rotation axis 213A of the rotation shaft 213 is set in the vertical direction.

Next, a method for forming the electron injection region 14 on the substrate 203 by using the vacuum evaporation apparatus 201 configured as described above will be specifically described. First, a planar square substrate 203 as shown in FIG. 7 is prepared, and this substrate 203 is engaged with the holding portion 212 of the substrate holder 211 to be in a horizontal state. In this regard, the fact that the substrate 203 shown in FIG. 7 is held in a horizontal state indicates this.

In forming the electron injection region 14, two adjacent evaporation sources 212 B on the virtual circle 221 are formed.
And 212C are filled with an electron transporting compound and an electron injecting material (reducing dopant), respectively, and then a predetermined degree of vacuum, for example, 1.
The pressure is reduced until the pressure becomes 0 × 10 ⁻⁴ Torr.

Next, the evaporation sources 212B and 212C are heated to simultaneously evaporate the electron-transporting compound and the reducing dopant from the evaporation sources 212B and 212C, respectively. 213A is rotated at a predetermined speed, for example, 1 to 100 rpm. In this manner, the electron injection region 14 is formed by co-evaporating the electron transporting compound and the reducing dopant while rotating the substrate 203. At this time, as shown in FIG.
2C is provided at a position shifted by a predetermined distance M in the horizontal direction from the rotation axis 213A of the substrate 203, so that the rotation of the substrate 203 reduces the incident angle of the electron transporting compound and the reducing dopant to the substrate 203. Can be changed regularly. Therefore, the deposition material is
To the electron injection region 14
In the film surface of (1), a thin film layer in which the composition ratio of the evaporation material is uniform, for example, the concentration unevenness is ± 10% (in terms of mol) can be surely formed. Further, by performing the vapor deposition as described above, the substrate 203 does not need to revolve, so that space and equipment are not required, and the film can be formed economically with a minimum space. Revolving the substrate means rotating around a rotation axis other than the substrate, and requires a larger space than when rotating.

In carrying out the manufacturing method of the sixth embodiment, the shape of the substrate 203 is not particularly limited.
For example, as shown in FIG. 7, when the substrate 203 is in the shape of a rectangular flat plate, a plurality of evaporation sources 212 are formed along the circumference of a virtual circle 221 around the rotation axis 213A of the substrate 203.
A to 212F are provided, and when the radius of the virtual circle 221 is M and the length of one side of the substrate 203 is L, M> (1/2)
It is desirable to satisfy × L. When the lengths of the sides of the substrate 203 are not the same but different, the length of the longest side is set to L. With this configuration, the substrate 203 can be supplied from the plurality of evaporation sources 212A to 212F.
Since the angles of incidence of the vapor deposition material with respect to can be made the same, the composition ratio of the vapor deposition material can be more easily controlled. In addition, with this configuration, the evaporating material is evaporated at a constant incident angle with respect to the substrate 203, so that the evaporating material does not enter vertically and the uniformity of the composition ratio in the film plane is further improved. be able to.

In carrying out the manufacturing method according to the sixth embodiment, as shown in FIG.
To 212F are arranged on the circumference of a virtual circle 221 centered on the rotation axis 213A of the substrate 203, and the plurality of evaporation sources 21
When the number (number) of the arrangements 2A to 212F is n, it is preferable that the evaporation sources 212A to 212F are arranged at an angle of 360 ° / n from the center of the virtual circle 221. For example, when six evaporation sources 212 are provided, the virtual circle 22
It is preferable to arrange them at an angle of 60 ° from the center of one. With this arrangement, a plurality of deposition materials can be sequentially formed on each portion of the substrate 203, so that thin film layers having composition ratios that are regularly different in the thickness direction of the film can be easily formed. can do.

Next, the uniformity of the thin film layer formed by the manufacturing method of the sixth embodiment will be described in more detail. As an example, Alq is used as the electron transporting compound, Cs is used as the reducing dopant, and the substrate 203 shown in FIG.
Was rotated at 5 rpm, and a thin film layer having a thickness of about 1000 angstroms (set value) was co-deposited under the following conditions. Alq steaming speed: 0.1-0.3 nm / s Cs steaming speed: 0.1-0.3 nm / s Alq / Cs film thickness: 1000 Å (set value)

Next, the thickness of the obtained thin film layer at the measurement points (4A to 4M) on the glass substrate 203 shown in FIG.
X-ray photoelectron spectroscopy (XPS)
It measured using. Note that the glass substrate 203 shown in FIG.
The upper measurement points (4A to 4M) divide the surface of the substrate 203 into 16 equal parts in advance, set square sections with a side length P of 50 mm, and set any corners (13 places) in these sections. ). Table 1 shows the obtained results.

[0155]

[Table 1]

On the other hand, except that the 203 is not rotated, the sixth
A thin film layer having a thickness of about 1000 angstroms (set value) was formed in the same manner as in the manufacturing method of the embodiment. Note that the evaporation conditions are as described above. Next, the film thickness and the composition ratio (atomic ratio) of Cs / Al at the measurement points (4A to 4M) of the obtained thin film layer were measured.
Shown in

[0157]

[Table 2]

As is apparent from these results, when the manufacturing method of the sixth embodiment is used, the film thickness is within the range of 1008 to 1093 angstroms at the measurement points (4A to 4M) on the substrate 203. Extremely uniform thickness and Cs / Al composition ratio (atomic ratio) of 1.0 to 1.10
It was confirmed that a thin film layer having a very uniform composition ratio within the range of was obtained. On the other hand, when a manufacturing method different from that of the sixth embodiment is used, measurement points (4A to
4M), the film thickness is a value within the range of 884 to 1067 angstroms, and the Cs / Al composition ratio is 0.6 to
It was confirmed that the value was within the range of 1.3.

In the embodiments described above, examples in which the present invention is configured under specific conditions have been described. However, various changes can be made in this embodiment. For example, in the above-described embodiment, the light emitting region and the electron injection region are separately provided, but the light emitting region and the electron injection region may be combined into one layer. Also, between the cathode layer and the anode layer,
Any suitable layer, for example, an organic semiconductor layer or an inorganic semiconductor layer,
Alternatively, an adhesion improving layer may be inserted.

[0160]

[Embodiment 1] Next, the configuration of the organic EL element 102 of Embodiment 1 will be described in detail with reference to FIGS. 1, 7 and 8. FIG.

(1) Preparation for Manufacturing Organic EL Device In manufacturing the organic EL device 100 of Example 1, first, the thickness was 1.1 mm, the length was 200 mm, and the width was 200 m.
m as a positive electrode layer 10 on a transparent glass substrate 22
A transparent electrode film of O was formed. Hereinafter, this glass substrate 10
And the anode layer 10 together with the substrate 30 (in FIG. 7, the substrate 20
3). Subsequently, the substrate 30 was ultrasonically cleaned with isopropyl alcohol, further dried in an N ₂ (nitrogen gas) atmosphere, and then cleaned for 10 minutes using UV (ultraviolet rays) and ozone.

Next, as shown in FIG.
Attached to the substrate holder 211 of the vacuum chamber 210 of the vacuum deposition apparatus 201, the electron injection area 14 and the light emission area 12 are partially or entirely formed of a nitrogen-free aromatic ring represented by the formula (17). An aromatic compound (EM-2) is deposited on the evaporation source 212C, and a reducing dopant (Li) constituting a part of the electron injection region 14 is deposited on the evaporation source 212C.
D, a metal (Al) constituting the cathode layer 16 is deposited on the evaporation source 21.
2E. The glass transition point of EM-2 was 114 ° C., and the electron affinity of the electron injection region 14 including the glass transition point was 2.4 eV.

(2) Manufacture of Organic EL Device Next, after the pressure in the vacuum chamber 210 was reduced to a degree of vacuum of 5 × 10 ⁵ Torr or less, the light emitting region 12 and the electron injection were formed on the anode layer 10 of the substrate 30. The organic EL device 100 was obtained by sequentially laminating the region 14 and the cathode layer 16 in this order. In addition,
At this time, during the period from the formation of the light emitting region 12 to the formation of the cathode layer 16, the organic EL element
00 was produced.

More specifically, EM-2 as the organic light emitting material was heated and evaporated from the evaporation source 212C, and the organic light emitting region 12 was deposited on the anode layer 10 under the following conditions. EM-2 steaming speed: 0.1 to 0.3 nm / s EM-2 film thickness: 40 nm

Next, the evaporation source 212C and the evaporation source 21
From 2D, EM-2 and Li were simultaneously evaporated under the conditions shown below, and the organic luminescent region 12 was obtained under the following conditions.
An electron injection region 14 was formed thereon. EM-2 steaming speed: 0.1 to 0.3 nm / s Li steaming speed: 0.05 to 0.01 nm / s EM-2 / Li composition ratio: 1/1 (atomic ratio) EM- 2 / Li film thickness: 20 nm

In the simultaneous vapor deposition, Embodiment 6
According to the method shown in FIG. That is, the evaporation sources 212C and 212D are connected to the rotation axis 2 of the substrate 30 (substrate 203).
13A is provided at a position shifted by 30 mm in the horizontal direction from each of the vapor deposition sources 212A.
EM-2 and Li were simultaneously evaporated from C and 212D, respectively, and the motor 214 was rotated and disturbed to form the electron injection region 14 while rotating the substrate 203 at 5 rpm along the rotation axis 213A.

Finally, Al was evaporated from the evaporation source 212E under the following conditions to deposit the cathode layer 16 on the electron injection region 14. Al evaporation speed: 1 nm / s Al film thickness: 200 nm

(3) Evaluation of Organic EL Device In the obtained organic EL device 100, a negative (−) electrode was used as the cathode layer 16 and a positive (+) electrode was used as the anode layer 10, and a DC voltage of 7 V was applied between both electrodes. did. The current density at this time was 1.0 mA / c as shown in Table 1 below.
m ² , and the luminance at that time is 37 cd / cm ² ,
The emission color was blue. The organic EL device 100
Had a half-life of 800 hours. Note that the half life is the time required for the luminance to reach half the maximum luminance. For example, in the first embodiment, the maximum luminance is 100 cd.
/ M ² to the half value of 50 cd / m ² .

[0169]

[Table 3]

Embodiment 2 Next, Embodiment 2 of the present invention will be described. The structure of the organic EL device of Example 2 was the same as the structure of the organic EL device 100 of Example 1, and was manufactured in the same manner as in Example 1. However, in Example 2,
EM-3 represented by Formula (23) was used instead of EM-2 in Example 1. The glass transition point of EM-3 is
The temperature was 108 ° C., and the electron affinity of the electron injection region including the temperature was 2.5 eV. Then, a DC voltage of 7 V was applied to the obtained organic EL element 100 in the same manner as in Example 1. As a result, blue light emission was observed. At that time, the current density was 1.3 mA / cm ² and the light emission luminance was 41 cd.
/ M ² . The half life of the organic EL device of Example 2 was 700 hours.

[Comparative Example 1] Next, Comparative Example 1 will be described. The structure of the organic EL device of Comparative Example 1 is the same as the structure of Example 1. However, in Comparative Example 1, only trinitrofluorenone (TNF) represented by the following formula (34) was used instead of EM-2 / Li used in Example 1 as a material for the electron injection region. The electron affinity in the electron injection region in this case was 4.1 eV. In addition, each layer other than the light emitting region was made of the same material and film thickness as in Example 1.

[0172]

Embedded image

Then, a DC voltage of 7 V was applied to the organic EL device in the same manner as in Example 1. The current density at this time is
It was 0.1 mA / cm ² , and no luminance was observed.
In the organic EL device of Comparative Example 1, since the electron affinity in the electron injection region was as high as 4.1 eV, it is considered that TNF reacted with the material in the light emission region to form a complex.

[Comparative Example 2] Next, Comparative Example 2 will be described. The structure of the organic EL element of Comparative Example 2 is the same as the structure of Example 1. However, in Comparative Example 2, diphenoquinone (DFQ) represented by the following formula (35) was used instead of EM-2 / Li used in Example 1 for the material of the electron injection region.
Was used. In this case, the glass transition point of the electron injection region is 5
The temperature was 0 ° C., and the electron affinity in the electron injection region was 4.0 eV. The layers other than the electron injection region were made of the same material and thickness as in Example 1.

[0175]

Embedded image

Then, a voltage of 7 V was applied to the organic EL device in the same manner as in Example 1. The current density at this time is 0.
It was ² mA / cm ² , and the luminance was instantaneously obtained at ² cd / m ² , but was immediately extinguished. In the organic EL device of Comparative Example 2, since the material of the electron injection region contained nitrogen atoms and the glass transition point was as low as 50 ° C., it is considered that the electron injection region was destroyed by Joule heat.

[Comparative Example 3] Next, Comparative Example 3 will be described. The structure of the organic EL device of Comparative Example 3 is the same as the structure of Example 1. However, in Comparative Example 3, instead of EM-2 / Li used in Example 1, a nitrogen-containing compound bathocuproin (Bathocuproin, BCP) represented by the following formula (36) was used as the material for the electron injection region. . In this case, the glass transition point of the electron injection region was 62 ° C., and the electron affinity of the electron injection region was 2.8 eV. The layers other than the electron injection region were made of the same material and thickness as in Example 1.

[0178]

Embedded image

Then, a DC voltage of 6 V was applied to the organic EL device. The current density at this time was 1.0 mA / cm
² and the luminance was 90 cd / m ² . But organic E
The half life of the L element was only 200 hours. Also,
Observation of the emission spectrum revealed that a spectrum component emitting red light was generated. Since the nitrogen-containing compound used in Comparative Example 3 has a strong acceptor property, it is considered that the nitrogen-containing compound interacted with a material in the light emitting region to cause quenching. In other words, it is considered that the nitrogen-containing compound used has a molecular weight of 300 or less and has a low glass transition point, so that it can be easily mixed with the light-emitting region, and as a result, the quenching is caused by the interaction.

[0180]

As described above in detail, according to the first aspect of the present invention, the interface between the electron injection region and the light emission region is
The generation of a charge transfer complex or an exciplex having low luminous efficiency can be suppressed, and the occurrence of a blocking junction unfavorable in injecting electrons from the electron injection region to the light emission region can also be suppressed. Therefore, according to the present invention, luminous efficiency can be improved (for example, light emission luminance is 30 cd / m ² or more) at low voltage driving (for example, DC voltage of 7 V or less),
Further, an organic EL element having a longer life (for example, a half life of 500 hours or more) can be provided.

Further, according to the second aspect of the present invention, not only when an aromatic ring compound containing no nitrogen atom is used, but also an aromatic ring compound containing an aromatic ring containing a nitrogen atom is used. Even in this case, it is possible to suppress the generation of a charge transfer complex or exciplex having low luminous efficiency at the interface between the electron injection region and the light emitting region, and it is preferable in injecting electrons from the electron injection region to the light emitting region. It has also become possible to suppress the occurrence of no blocking junction. Therefore, according to the second aspect of the present invention, the restrictions on the materials used are reduced, a greater degree of freedom in design is obtained, and the luminous efficiency is improved in low-voltage driving (for example, DC voltage of 7 V or less). (For example,
It has become possible to provide an organic EL device having an emission luminance of 40 cd / m ² or more and a longer life (for example, a half life of 500 hours or more).

[Brief description of the drawings]

FIG. 1 is a sectional view of an organic EL device according to first and second embodiments.

FIG. 2 is a sectional view of an organic EL device according to a third embodiment.

FIG. 3 is a cross-sectional view of an organic EL device according to a fourth embodiment.

FIG. 4 is a sectional view of an organic EL device according to a fifth embodiment.

FIG. 5 is a sectional view of an organic EL element according to a modification of the third embodiment.

FIG. 6 is a sectional view of an organic EL element according to a modification of the fourth embodiment.

FIG. 7 is a perspective view of a vacuum evaporation apparatus according to a sixth embodiment.

FIG. 8 is a sectional view of a vacuum evaporation apparatus according to a sixth embodiment.

FIG. 9 is a diagram provided for describing measurement points on a substrate.

FIG. 10 is a sectional view of a conventional organic EL element.

[Explanation of symbols]

 Reference Signs List 10 anode layer 12 light emitting area 14 electron injection area 16 cathode layer 18 hole injection transport layer 20 translucent substrate (glass substrate) 30 substrate 100, 102, 104 organic EL element 201 vacuum evaporation apparatus 203 substrate 210 vacuum tank 211 substrate holder 212 Holder 212A to 212F Evaporation source 213 Rotation axis 213A Rotation axis 214 Motor 221 Virtual circle

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09K 11/06 645 C09K 11/06 645 655 655 H05B 33/14 H05B 33/14 A

Claims (21)

[Claims] 1. An organic electroluminescence device having a structure in which at least an anode layer, an organic light-emitting region, an electron injection region, and a cathode layer are sequentially laminated, wherein the electron injection region includes an aromatic ring containing no nitrogen atom. Containing an aromatic ring compound and a reducing dopant, and having an electron affinity in the electron injection region of 1.8 to 3.6.
a value within the range of eV, and the organic light-emitting region contains an aromatic ring compound having any one styryl group represented by the following general formulas (1) to (3). Organic electroluminescent element. Embedded image [In the general formula (1), Ar ¹ is an aromatic group having 6 to 40 carbon atoms, and Ar ² , Ar ³ , and Ar ⁴ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. And A
At least one of r ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is an integer of 1 to 6. ] [In the general formula (2), Ar ⁵ is an aromatic group having 6 to 40 carbon atoms, Ar ⁶ and Ar ⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and ⁵ , Ar ⁶
And at least one of Ar ⁷ is substituted with a styryl group, and the condensation number m is an integer of 1 to 6. ] [In the general formula (3), Ar ⁸ and Ar ^{14 each} have 6 carbon atoms.
Ar ^{9 to} Ar ¹³ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms,
At least one of r ^{8 to} Ar ¹⁴ is substituted with a styryl group, and the condensed numbers p, q, r, and s are 0 or 1 respectively.
It is. ] 2. The organic electroluminescence device according to claim 1, wherein the styryl group is a styryl group represented by the following general formula (4). Embedded image [In the general formula (4), Ar ¹⁵ Ar ¹⁶ and Ar ¹⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. ] 3. The organic electroluminescent device according to claim 1, wherein a glass transition point of the electron injection region is set to a value of 100 ° C. or more. 4. The organic electroluminescence device according to claim 1, wherein the aromatic ring in the aromatic ring compound is anthracene, fluorene, perylene, pyrene, phenanthrene, chrysene, tetracene, or rubrene. An organic electroluminescent device, comprising at least one aromatic ring selected from the group consisting of terphenylene, quarterphenylene, sexiphenylene, and triphenylene. 5. The organic electroluminescence device according to claim 1, wherein the aromatic ring in the aromatic ring compound has a styryl group-substituted aromatic ring or a distyryl group-substituted aromatic ring. An organic electroluminescence device comprising at least one aromatic ring selected from the group consisting of an aromatic ring and a tristyryl group-substituted aromatic ring. 6. The organic electroluminescence device according to claim 1, wherein the reducing dopant is an alkali metal, an alkaline earth metal, a rare earth metal, an oxide of an alkali metal, or an alkali metal. An organic electroluminescent material comprising at least one substance selected from the group consisting of halides, alkaline earth metal oxides, alkaline earth metal halides, rare earth metal oxides, and rare earth metal halides. Luminescent element. 7. The organic electroluminescence device according to claim 1, wherein the work function of the reducing dopant is 3.0 eV or less. 8. The organic electroluminescence device according to claim 1, wherein the reducing dopant is at least one alkali selected from the group consisting of Li, Na, K, Rb and Cs. An organic electroluminescence device, which is a metal. 9. The organic electroluminescent device according to claim 1, wherein an energy gap of the electron injection region is set to a value of 2.7 eV or more. 10. The organic electroluminescence device according to claim 1, wherein the addition ratio of the aromatic ring compound to the reducing dopant is 1:20.
An organic electroluminescence device characterized in that the value is within a range of 20 to 1: 1 (molar ratio). 11. The organic electroluminescence device according to claim 1, wherein the light emitting region and the electron injection region are of the same kind of aromatic ring comprising an aromatic ring containing no nitrogen atom. An organic electroluminescence device comprising a ring compound. 12. The organic electroluminescence device according to claim 1, wherein the cathode layer and the electron injection region and / or the anode layer and the emission region. On the other hand, an organic electroluminescence device characterized by providing an interface layer. 13. An organic electroluminescence device having a structure in which at least an anode layer, a light emitting region, an electron injection region, and a cathode layer are sequentially laminated, wherein the electron injection region has an electron transporting compound and a work function of 2.9 eV. Including the following reducing dopant,
The electron affinity of the electron injection region is set to a value within a range of 1.8 to 3.6 eV, and the organic light emitting region includes any one of styryl groups represented by the following general formulas (1) to (3). An organic electroluminescent device comprising an aromatic ring compound having the formula: Embedded image [In the general formula (1), Ar ¹ is an aromatic group having 6 to 40 carbon atoms, and Ar ² , Ar ³ , and Ar ⁴ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. And A
At least one of r ¹ , Ar ² , Ar ³ and Ar ⁴ is an aromatic group, and the condensation number n is an integer of 1 to 6. ] [In the general formula (2), Ar ⁵ is an aromatic group having 6 to 40 carbon atoms, Ar ⁶ and Ar ⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms, and Ar 5 ⁵ , Ar ⁶
And at least one of Ar ⁷ is substituted with a styryl group, and the condensation number m is an integer of 1 to 6. ] [In the general formula (3), Ar ⁸ and Ar ^{14 each} have 6 carbon atoms.
Ar ^{9 to} Ar ¹³ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms,
At least one is substituted with a styryl group, condensation number p, q, r, s of r ⁸ to Ar ¹⁴ are each 0 or 1
It is. ] 14. The organic electroluminescent device according to claim 13, wherein the styryl group is a styryl group represented by the following general formula (4). Embedded image [In the general formula (4), Ar ¹⁵ Ar ¹⁶ and Ar ¹⁷ are each a hydrogen atom or an aromatic group having 6 to 40 carbon atoms. ] 15. The organic electroluminescence device according to claim 13, wherein said reducing dopant is Na, K, Rb, Cs, Ca, Sr and B.
An organic electroluminescent device, characterized in that it is at least one alkali metal or alkaline earth metal selected from the group consisting of: a. 16. The organic electroluminescent device according to claim 13, wherein the electron-transporting compound includes a nitrogen-containing heterocyclic compound. 17. The organic electroluminescent device according to claim 16, wherein the nitrogen-containing heterocyclic compound is selected from the group consisting of a nitrogen-containing complex, a quinoline derivative, a quinoxaline derivative, an oxadiazole derivative, a thiadiazole derivative, and a triazole derivative. An organic electroluminescence device, which is at least one compound to be produced. 18. The organic electroluminescence device according to claim 13, wherein an addition ratio of the electron transporting compound and the reducing dopant is 1:20 to 20: 1 (molar ratio). An organic electroluminescent device, wherein the value is within a range. 19. The organic electroluminescence device according to claim 13, wherein a glass transition point of the electron injection region is set to a value of 100 ° C. or more. 20. The organic electroluminescent device according to claim 13, wherein the light emitting region and the electron injection region contain the same type of electron transporting compound. Organic electroluminescent element. 21. The organic electroluminescence device according to claim 13, wherein the cathode layer and the electron injection region and / or the anode layer and the light emission region. On the other hand, an organic electroluminescence device characterized by providing an interface layer.