JPS6147783A - El element - Google Patents

Abstract

PURPOSE:The titled element having improved emission intensity, capable of changing arbitrarily luminous color, having extremely prolonged life, having luminous layers consisting of plural layers, wherein each layer comprises a specific thin film containing at least one electrically luminous organic compound. CONSTITUTION:For example, a monomolecular accumulated layer consisting of the electrically luminous organic compound A (e.g., compound shown by the formula I, etc.) 4 and the organic compound (e.g., compound shown by the formula II, etc.) 4' having electron donor properties relatively based on the compound A is piled as the first layer on the transparent electrode 1 obtained by depositing an ITO layer on a glass plate by sputtering method, and the electrically luminous organic compound(e.g., anthracene, etc.) 5 having the same electronegativity as that of the compound A is piled as the second layer on the first layer. Then, the compound A or the electrically luminous organic compound 6 having the same electronegative as that of the compound A and the organic compound(e.g., compound shown by the formula III, etc.) 6' having electron donor properties relatively based on the compound A is piled as the third layer on the second layer, and finally A1 is deposited as the back electrode 3, to give the aimed element.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an EL element using electrical light emission, that is, EL, and more specifically, the present invention relates to an EL element using electrical light emission, that is, EL, and more specifically, the light emitting layer has a three-layer structure,
The present invention relates to an EL device, each layer comprising a thin film of at least one electroluminescent organic compound.

(Prior art) Conventional EL elements are made of Mn, Cu, or ReF3 (
It consists of a light-emitting layer whose light-emitting base material is ZnS containing Re (rare earth ions) as an activator, and is structurally divided into powder-type EL and thin-film EL, depending on the basic structure of the light-emitting layer. Ru.

Among devices that have been put into practical use, thin-film ELs generally have higher brightness than powder-type ELs, but because thin-film ELs form a light-emitting layer by vapor-depositing a light-emitting base material onto a substrate, they are not suitable for large-area devices. It has the drawbacks that it is difficult to manufacture and the manufacturing cost is very high.

For this reason, powder-type EL, in which a light-emitting base material, that is, ZnS, is dispersed in an organic binder, which is most easily mass-produced and costs only a few tenths of the cost of thin-film devices, has attracted attention. Generally, in EL light emission, the thinner the thickness of the light emitting layer, the better the light emission characteristics. However, the powder 5
In the case of EL, the luminescent base material is a discontinuous powder, so if the luminescent layer is thinned, pinholes are likely to occur in the luminescent layer.
It has a major drawback in that it is difficult to reduce the layer thickness, and therefore sufficient brightness characteristics cannot be obtained. Recently, an improved device in which an intermediate dielectric layer made of a polyvinylidene fluoride polymer is disposed within the light-emitting layer of the powder type EL has been disclosed in Japanese Patent Publication No. 172891/1982. ,
It has not yet achieved sufficient performance in terms of luminance, power consumption, etc. On the other hand, recently, research and development has been actively conducted to control the chemical structure and higher-order structure of organic materials to create new materials for optical and electronics.
Organic materials, such as piezoelectric elements, pyroelectric elements, nonradiometer optical elements, and ferroelectric liquid crystals, have been announced that are comparable to or superior to metals and inorganic materials. As described above, there is a demand for the development of functional organic materials as new functional materials that surpass inorganic materials, and a cumulative film of monomolecular layers of anthracene derivatives and pyrene derivatives, which have a parent tree group and a hydrophobic group in the molecule, is being used as an electrode. The EL element formed on the substrate was disclosed in Japanese Patent Application Laid-Open No. 52-3558.
This is proposed in Publication No. 7. However, these EL devices have not achieved sufficient performance in terms of brightness, power consumption, etc. as actual EL devices, and furthermore, in the case of organic EL devices, the density of carrier electrons or holes is extremely small. , the probability of excitation of functional molecules due to carrier recombination etc. becomes extremely small, and efficient light emission cannot be expected.

(Disclosure of the Invention) Therefore, an object of the present invention is to solve the above-mentioned drawbacks of the prior art, and to provide an EL element that can emit light with sufficiently high brightness even when driven at a low voltage, is inexpensive, and is easy to manufacture. It is to provide.

The first aspect of the present invention is achieved by forming the light-emitting layer of the EL element by combining specific materials and having a specific configuration.

That is, the present invention provides an EL device comprising a light emitting layer having a three-layer stacked structure and two electrode layers sandwiching the light emitting layer, at least one of which is transparent, in which the first light emitting layer is electrically Consisting of a monomolecular film or a cumulative film thereof consisting of a luminescent organic compound (A) and at least one organic compound (hereinafter referred to as a donor) that is relatively electron-donating to the compound ('A), The second light-emitting layer is made of a molecular deposited film made of the electroluminescent organic compound (A) or an electroluminescent organic compound having the same electrical stoichiometry as the compound (A),
and the third layer is relatively electron-accepting to the electroluminescent organic compound and compound (A) having the same electrophilicity as the electroluminescent organic compound (A) or compound CA). The above-mentioned EL device is characterized in that it is composed of a monomolecular film made of at least one kind of organic compound (hereinafter referred to as an acceptor) or a cumulative film thereof.

To explain the present invention in detail, the electroluminescent organic compound used in the present invention and which mainly characterizes the present invention has a high luminescence quantum efficiency and is easily susceptible to external perturbation.
Basically, it is a compound that has an electronic system and can be electrically excited.

Fused polycyclic aromatic hydrocarbon, p-terphenyl, 2.5-
Difecol oxazole, 1,4-bis(2-methylstyryl)-benzene, xanthine, coumarin, acridine, cyanine dye, benzophenone, phthalocyanine and its metal complex, porphyrin and its metal complex,
Examples include 8-hydroxyquinoline and its metal complexes, organic ruthenium complexes, organic rare earth complexes, and derivatives of these compounds. Furthermore, compounds that can serve as electron acceptors or electron donors for the above compounds include heterocyclic compounds other than those mentioned above and derivatives thereof, aromatic amines and aromatic polyamines, compounds with a quinone structure, and tetracyanoquinodimethane. and tetracyanoethylene.

In the present invention, the compounds useful for forming the first and third light-emitting layers are obtained by chemically modifying the electroluminescent compounds as described above by known methods as necessary, and at least It is a compound that has one hydrophobic part and at least one wood-loving part (both of which are in a relative sense), and is, for example, a compound represented by the following general formula (I). and other compounds.

[(x-n,), zl,, -$-R2(r) In the above formula, X is a hydrogen atom, a halogen atom, an alkoxy group, an alkyl ether group, a nitro group; a carboxyl group, a sulfonic acid group, a phosphoric acid group group, silicic acid group, 1st to 3rd amino group;
These metal salts, primary to tertiary amine salts, acid salts; ester groups, sulfamide groups, amide groups, imino groups, quaternary amine groups, salts thereof, hydroxyl groups, etc.; R2 has 4 to 4 carbon atoms;
30, preferably 10 to 25 alkyl groups, preferably linear alkyl groups; m is 1 or -So, NR
Linking group such as 1,-CO-1-C00- (R, is any substituent such as hydrogen atom, alkyl group, aryl, etc.)
and: φ is a residue of an electroluminescent compound as exemplified later; R2 is a hydrogen atom or any other substituent like X; 14N or multiple X, φ and R
At least one of 2 is a hydrophilic part, and at least one is a hydrophobic part.

Further, in the present invention, the organic compound useful for forming the second light emitting layer may be the same compound as above,
In addition, compounds of the same type as those mentioned above are used, except for those that have been chemically modified.

Preferred examples of compounds of general formula (I) useful for forming the first and third layers, basic skeletons of compounds useful for forming the second layer, and other compounds include the following: That's right.

(However, φ (basic skeleton) illustrated below has 1 to 1 carbon atoms.
4 alkyl group, alkoxy group, alkyl ether group,
It may have general substituents such as a halogen atom, a nitro group, a primary to tertiary amino group, a hydroxyl group, a carboxamide group, and a sulfoamide group. )Z=NH,0,S Z=CO,
NHZ=CO1NH,0,5Z=NH,0,S z = NH,OlS Z=NH
%O,5Z=S1Se z-81se
z=s1sez=NH,0,S Z=NH1(l
sZ=NH1O, SM=Mg, Zn, Sn, A
l, C1M=Hz, Be, Mg, Ca, CdSn, Al
C1, YbC1 M=Er, Trr4 Sm, Eu, Tb,
Z=0, NnM-A4 Ga, Ir, Ta, a=3
M=Er, Sm, Eu stop Znt Cd i Mg,
pb ta-2Gd ITb * Dymi Yb M-Er * Smi Eu , Gd M-Er
, Smi EuTb, py, Tm, Yb
Gd, Tb, DyTm, Yb 2=0, S, SeO≦p≦2 The above luminescent compounds can be used alone or as a mixture in each luminescent layer in the present invention. In addition,
These compounds are examples of preferred compounds, and it is natural that other derivatives or other compounds may be used as long as the same purpose is achieved.In the present invention, from the above-mentioned luminescent compounds, specific Selecting at least one preferred compound (A), combining the compound (A) with a donor to form a first layer,
Next, a second layer is formed from the compound (A) or an electroluminescent organic compound having a similar electroconductivity as the compound (A),
Finally, a third layer is formed by combining Compound (A) or an electroluminescent organic compound with a similar electricality to Compound (A) with an acceptor to form a laminate structure of three layers. It is characterized by

Among such luminescent compounds, compounds preferred as compound (A) are those having intermediate electronegativity and excellent luminous efficiency among the above-mentioned exemplified compounds.

In addition, particularly preferable compounds as donors are first to third
The main compounds are the above-mentioned luminescent compounds or other organic compounds having an electron-donating group such as a class amine 7 group, a hydroxyl group, an alkoxy group, an alkyl ether group, or a nitrogen heteroatom, and as an acceptor, a carbonyl group, a carbonyl group, The luminescent compounds or other organic compounds having an electron-withdrawing group such as a sulfonyl group, a ditro group, or a quaternary amino group are mainly used. In the present invention, such luminescent compounds, donors, or acceptors can be used alone or in combination in each luminescent layer.

The other elements forming the EL element of the present invention, that is, the two electrode layers sandwiching the light emitting layer, can be any conventionally known element, but at least one of the layers must be transparent. There is a need. As the transparent electrode, any desired transparent electrode layer can be used as in the past. Preferably, transparent electrode layers such as transparent synthetic resins such as polymethyl methacrylate and polyester, or transparent films or sheets such as glass or the like can be used. A transparent conductive material such as indium oxide, tin oxide, or indium-tin-oxide (ITo) is coated on the entire surface or in a pattern. When opaque electrodes are used on one side, these opaque electrodes may be of conventionally known types, and are generally and preferably made of aluminum, silver, gold, etc. with a thickness of approximately 0.1-0.3 μm. This is the vapor-deposited film. Further, the shape of the transparent electrode or the opaque electrode may be any shape such as a rainbow shape, a belt shape, a cylindrical shape, etc., and can be selected depending on the purpose of use. The thickness of the transparent electrode is preferably about 0.01 to 0.21 m. If the thickness is less than this range, the physical strength and electrical properties of the element itself will be insufficient, and if the thickness is less than this range, the physical strength and electrical properties of the element itself will be insufficient. , there is a risk of problems with transparency, light weight, compactness, etc.

In the EL element of the present invention, between the two electrode layers as described above,
It is obtained by forming a light-emitting layer consisting of three layers having relatively different electronegativities as described above, and in the light-emitting layer of the formed three-layer structure, the molecules constituting the first and third M are , are each a monomolecular film or a cumulative film thereof arranged with highly ordered molecular orientation, and are characterized in that the second layer is a molecular deposition film.

In the present invention, a particularly preferred method for forming such a monomolecular film or a cumulative film thereof is the Langmuir-Blodgett method (LB method). In this LB method, when a molecule has a structure that has a hydrophilic group and a hydrophobic group in the molecule, and the balance between the two (balance of amphiphilicity) is maintained appropriately, the molecule is placed on the water surface This is a method of forming a monomolecular film or a cumulative film thereof by utilizing the fact that the monomolecular layer is formed with the functional groups facing downward. Specifically, in order to prevent the monomolecular film spread on the water layer from freely diffusing and spreading too much, a partition plate (or float) is provided to limit the spread area and control the aggregated state of the film material. is controlled, the surface pressure is gradually increased, and a surface pressure suitable for manufacturing a monomolecular film or a cumulative film thereof is set. By gently raising or lowering the clean substrate vertically while maintaining this surface pressure, the monolayer is transferred onto the substrate. Although a monomolecular film is manufactured in the above manner, a cumulative film of a monomolecular film is formed by repeating the above-described operations as a cumulative film having a desired degree of accumulation.

In addition to the above-mentioned vertical dipping method, the monomolecular film can be transferred onto the substrate by methods such as a horizontal deposition method and a rotating cylinder method. The horizontal deposition method is a method in which the substrate is brought into horizontal contact with the water surface and transferred, and the rotating cylinder method is a method in which a cylindrical substrate is rotated on the water surface to transfer the monomolecular film onto the surface of the substrate. In the above-mentioned vertical immersion method, when a substrate having one surface that is hydrophilic is lifted out of water in a direction transverse to the water surface, a monomolecular film is formed on the substrate with the wood-loving groups of the molecules facing the substrate side. As mentioned above, when the substrate is moved up and down, one monomolecular film is overlapped in each process.The direction of the film-forming molecules is reversed between the lifting process and the dipping process, so according to this method, the molecules between each layer are A Y-shaped film is formed in which the woody groups of the molecules face each other, and the hydrophobic groups of the molecules face each other. On the other hand, the horizontal adhesion method is a method in which a substrate is attached horizontally to the water surface and then transferred, and a monomolecular film with the hydrophobic groups of the molecules facing the substrate is formed on the substrate. In this method, even if monomolecular films are accumulated, there is no change in the direction of the film-forming molecules, and an X-shaped film is formed in which the hydrophobic groups face the substrate in all layers. In the 0-rotation cylinder method, a cumulative film in which the tree-philic group faces the substrate is called an X-type film, in which a monomolecular film is transferred to the surface of the substrate by rotating the cylinder above the water surface of the substrate. The method of transferring the monomolecular film onto the substrate is not limited to these methods; in other words, when using a large-area substrate, a method of extruding the substrate from a substrate roll into a water layer may also be used. Furthermore, the directions of the above-mentioned hydrophilic groups and hydrophobic groups toward the substrate are in principle, and can be changed by surface treatment of the substrate, etc.

In the present invention, particularly preferred methods for forming the molecular deposition film constituting the second light emitting layer are resistance heating evaporation method and CVD method. It is possible to form a thin film of about

For example, when using the resistance heating evaporation method, the material is placed in a tungsten board placed in a vacuum chamber, there is no layer over 30c from the substrate, resistance heating is performed, sublimable materials are set at the sublimation temperature, and meltable materials are set at the sublimation temperature. Vapor deposition is performed at a temperature above the melting point. The pre-vacuum level is set to 2 x 10-' Torr or less, the port is closed with a shutter before vapor deposition, the port is heated and the air is blown for 2 minutes, and then the shutter is opened to perform vapor deposition.

The speed during deposition is measured using a crystal oscillator film thickness monitor, but a suitable speed is 0.1 person/5ec-
This is carried out at a rate of 100λ/sec.

The degree of vacuum at that time is to-'T to prevent oxidation etc.
This is carried out by maintaining the pressure at or below 10 Torr, preferably about 10-' Torr.

In the EL device of the present invention, the above-mentioned light-emitting layer forming material is preferably formed into a three-layer structure having different electronegativity between the above-mentioned two electrode layers by using the above-mentioned LB method and molecular deposition film. It is obtained by forming. As mentioned in the conventional technology section, EL is obtained by the LB method.
Although it is known to form an EL element, the known method does not allow obtaining an EL element with sufficient performance.As a result of various studies, the inventor of the present invention determined that the light-emitting layer has a three-layer structure. The three light-emitting layers are formed as a monomolecular film or a cumulative film thereof using compounds with different electronegativities as described above, and the second
It has been discovered that the performance of prior art EL devices is significantly improved by forming the layers as molecular deposits.

One important aspect of the present invention is an aspect in which the first and third light-emitting layers are monomolecular films made of the above-mentioned light-emitting material. In the EL device of this embodiment, first, at least one compound (A) as described above is selected, and the compound (A) and the donor are preferably mixed in a ratio of 1:1/10 to 1:1/10.
in a suitable organic solvent such as chloroform, dichloromethane, dichloroethane, etc.
The solution is developed on an aqueous phase of an appropriate pH (e.g., pH about 1 to 8) that may contain various metal ions, and the solvent is removed by evaporation. A monomolecular film was formed, transferred onto one electrode substrate as the first layer by the LB method as described above, dried thoroughly, and then
A second layer is formed by forming a molecular deposited film from the compound (A) or an electroluminescent organic compound having the same electricality as the compound (A) by the above-mentioned molecular deposition method, and the surface of the second layer is Then, the above compound (A) or an electroluminescent organic compound having a similar electrophilicity as compound (A) and the acceptor are mixed by the LB method as described above, preferably in a ratio of about 1:1.
/10~l: 1/100 (71%71z ratio) to form a third layer, and finally, an electrode material such as aluminum, silver, gold, etc. is preferably deposited by vapor deposition to form a back electrode layer. It can be obtained by forming
In the above method, the same effect can be obtained even if the order of forming the first to third layers is reversed. The thickness of the light-emitting layer of the EL device thus obtained varies depending on the type of material used, but generally a thickness of about 0.01''lpm is suitable.

Another important embodiment is an embodiment in which at least one layer, preferably both layers, of the first and third layers constituting the light-emitting layer of the EL device of the present invention are cumulative films of the above-mentioned monomolecular films. be. This embodiment can be obtained by accumulating the above-mentioned monomolecular film by various methods to the required number of times and forming a molecular deposition film using the LB method and the molecular deposition method.

The thickness of the luminescent layer of the EL device thus obtained, that is, the cumulative number of monolayers, can be changed arbitrarily, but in the present invention, the first layer has a cumulative number of about 4 to 150 layers. , the third layer has a cumulative number of about 4 to 150, and the total thickness of the three layers is about 0.03 to 1 lm.

Note that the adhesion between the electrode layer used as a substrate and the light emitting layer is as follows.
In the LB method, the material is sufficiently strong and the light emitting layer will not peel or fall off, but in order to strengthen the adhesive strength, the substrate surface may be treated in advance or the light emitting layer and the substrate may be bonded together. A suitable adhesive layer may be provided between the two. Furthermore, the material for forming the luminescent layer and the p of the water layer used are
The adhesive strength can also be strengthened by adjusting various conditions such as H, ion species, water temperature, monomolecular film transfer rate, or monomolecular film surface pressure.

The performance of the EL element formed as described above may deteriorate due to the influence of moisture and oxygen in the air if left as is, so it is desirable to create a moisture- and oxygen-proof hermetically sealed structure using conventionally known means. .

In the EL device of the present invention as described above, the structure of the light emitting layer is as follows:
It is an ultra-thin film, and the first and third layers have a high degree of molecular order and function necessary for the operation of an EL device, and it has excellent light-emitting performance.

Furthermore, as schematically shown in FIG. 1, the emissive layer of the EL device of the present invention is different from the conventional single-layer emissive layer, and as schematically shown in FIG. Since the first to third light emitting layers are stacked with uniform interfaces, various interactions between these three layers with different electronegativities are extremely easy, which cannot be achieved with conventional technology. It exhibits excellent light emitting performance. That is, by variously changing the difference in electronegativity between the first to third light-emitting layers, the luminescence intensity can be improved, or the luminescence color can be arbitrarily changed, and its service life can also be significantly extended. be able to.

Furthermore, in conventional technology, materials with excellent luminescence properties but insufficient film formability and film strength could not be practically used; Even if the material has inferior but excellent luminescence properties, by using a material with excellent film-forming properties in at least one layer, it is possible to obtain a luminescent layer with excellent luminescence properties, film-forming properties, and film strength. .

The EL cable of the present invention described above has excellent EL by applying electrical energy such as alternating current, pulse or direct current between the electrode layers so that electrical energy such as a suitable electric field acts on the light emitting layer. This shows full luminescence.

Next, the present invention will be explained in more detail with reference to Examples. Note that the words in the middle of the text are based on weight.

Example 1 A transparent electrode was formed by depositing an ITO layer with a thickness of 1500 Å on the surface of a 50 mm square glass plate by sputtering.

After thoroughly cleaning this film-forming substrate, Joyce-Loebe
pH 6 of Langmuir-Trough4 made by 1 company
, immersed in an aqueous phase adjusted to 5. Next, A B C The above compounds A, B and C were dissolved in techloroform at a molar ratio of 5:5:1 (10-'+sol/l), and then developed on the above aqueous phase. After the solvent chloroform was removed by evaporation, the surface pressure was increased (30 dyne/cm) to precipitate the above mixed molecules in the form of a film. Thereafter, while keeping the surface pressure constant, the film-forming substrate is gently moved up and down in the direction across the water surface (vertical speed 2 c++/win), and the mixed monomolecular film is transferred onto the substrate. Only, 7
A mixed monomolecular cumulative film was created to form the first layer. During this accumulation step, each time the substrate was pulled out of the water tank, it was placed in a device for 30 minutes or more to evaporate and remove moisture adhering to the substrate.

Next, using a resistance heating evaporation apparatus, anthracene CD) (mp, 216°C) was evaporated to a thickness of 500 mm on the transparent electrode substrate provided with the above-mentioned mixed monomolecular film and its cumulative film. And so. This vapor deposition is carried out by first reducing the pressure in the vapor deposition tank to a vacuum level of 10'' Torr, gradually increasing the temperature of the resistance heating board (Mo), keeping the temperature constant at 216°C, and further increasing the pumping speed. Adjust the vacuum level to 9X10 Tor
A vapor deposited film was formed by adjusting the current flowing through the board containing anthracene so that the vapor deposition rate was 5 A/see. The degree of vacuum during vapor deposition is 9×10~' Torr
Met. Further, the temperature of the substrate holder was kept constant by circulating 20° C. water.

Next.

The compounds A, B and the compound E are used in a molar ratio of 5:5:1, and the same concentrations and methods as above are used to form a mixed monolayer alone and a third layer by accumulating 7 layers. did.

Finally, the substrate with the thin film formed as described above is placed in a vapor deposition tank, and the nuclide is once depressurized to a vacuum level of 10 Torr, and then the vacuum level is adjusted to 10 Torr, and the vapor deposition rate is 20.
AI was evaporated onto the thin film with a V thickness of 1500 at λ/sec to serve as a back electrode. As illustrated in FIG. 3, the produced EL device is sealed with a sealing glass, and then purified, degassed, and dehydrated silicone oil is injected into the seal according to a conventional method to produce an EL light-emitting cell of the present invention. Formed. When an AC voltage of IOV and 400 Hz was applied to these EL light emitting cells, when the first and third layers were monolayers, an EL with a current density of 0.17 mA/crn' and a brightness of 3.2 ft-I was obtained. When light emission is observed and the first and third layers are cumulative films, the current density is 0, 16 mA
EL emission with a brightness of 22.2 ft-L was observed.

The above-mentioned EL element of the present invention had a lower driving voltage and better luminance characteristics than the conventional EL element using ZnS as a light emitting matrix.

Comparative Example 1 In Example 1, except that only Compound A was used as the luminescent compound and a single layer was used, the rest was Example 1.
A comparative EL element was obtained in the same manner as in Example 1, and the luminance was 1 ft-L or less at a current density of 0.2 mA/cm'.6 Example 2 Compound C in Example 1 The EL device of the present invention (however, the following compounds F and G were used in place of F and E, and F G and others were carried out in the same manner as in Example 1).
The cumulative number of each was 7) and evaluated under the same conditions as in Example 1. At a current density of 0.08 mA/crrf, the luminance (
Ft-L) was 21.3't'.

[Brief explanation of the drawing]

FIG. 1 schematically shows an EL device using the LB method of the prior art, FIG. 2 schematically shows an EL device according to the present invention, and FIG. 3 schematically shows an EL device according to the present invention. It is a diagram schematically showing a cross section of an EL element. l; Transparent electrode 2; Luminescent layer 3; Back electrode 4; Luminescent compound 4'; Donor 5; Luminescent compound 6: Luminescent compound 6
'; Acceptor 7; Seal glass 8: Silicone insulating oil 9; Glass plate Patent applicant: Canon Co., Ltd. Figure 1 Figure 2 4'6' Figure 3

Claims (1)

[Claims] In an EL device comprising a light emitting layer with a three-layer stacked structure and two electrode layers sandwiching the light emitting layer, at least one of which is transparent, the first light emitting layer is made of an electroluminescent organic compound (A ) and at least one organic compound that is electron-donating relative to compound (A), or a cumulative film thereof, and the second light-emitting layer is composed of the electroluminescent organic compound (A). ) or an electroluminescent organic compound having the same electricality as that of compound (A), and the third layer is composed of the electroluminescent organic compound (A).
) or a monomolecular film or a cumulative film thereof consisting of an electroluminescent organic compound having the same electronegativity as compound (A) and at least one organic compound that is relatively electron-accepting to compound (A). The above-mentioned EL element is characterized by comprising: