JPS6155183A - El element - Google Patents

Abstract

PURPOSE:To titled element which has high luminance even on low-voltage drive and excellent emission quantum efficiency, and is low-priced, made by placing a luminescent layer of a specified two-layer constitution between two electrode layers at least one of which is transparent. CONSTITUTION:A luminescent layer 2 of a thickness of 0.01-1mum, having a two- layer constitution consisting of the first luminescent layer which faces a transparent electrode 1 and comprises a mixed unimolecular (cumulative) film of a mixture of 1mol of an electroluminescent organic compound 4 (A) and 0.1- 0.01mol of an oganic compound 4' (B) that is electron accepting relative to component A; and the second luminescent layer which faces a back electrode 3 and comprises and accumulated mixed molecular film of a thickness of about 500Angstrom , of a mixture of 1mol of component A or an electroluminescent organic compound 5 (C) having the same degree of electronegatively as component A and 0.1-0.01mol of an organic compound 5' (D) that is electron donating relative to component A or C, is formed between the transparent electrode 1 of a thickness of 0.01-0.2mum and the opaque back electrode 3 of a thickness of 0.1-0.3mum.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to an EL device using electrical light emission, that is, EL, and more specifically, one light emitting layer has a two-layer structure,
The present invention relates to an EL device comprising a thin film of at least one electroluminescent organic compound in which each layer has a different electronegativity relative to other adjacent layers.

(Prior art) Conventional EL elements are made of Mn, Cu or Re Fy.
Zn containing (Re; rare earth ion) etc. as an activator
It consists of a light-emitting layer using S as a light-emitting base material, and is broadly classified structurally into powder-type EL and thin-film type EL, depending on the basic structure of the light-emitting layer.

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, in the case of the powder type EL, since the luminescent base material is a discontinuous powder, pinholes are likely to occur in one luminescent layer when one luminescent layer is made thin.
It has a major drawback in that it is difficult to reduce the layer thickness, and therefore sufficient brightness characteristics cannot be obtained. Recently, the powder y! An improved device in which an intermediate dielectric layer made of vinylidene fluoride polymer is disposed within the light-emitting layer of 1iEL is shown in Publication No. 58-172891, but it is still insufficient in terms of luminance, power consumption, etc. However, 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 that are fully refractive and comparable to or superior to inorganic materials have been announced, such as elements, piezoelectric elements, pyroelectric elements, non-radiometer optical elements, and ferroelectric liquid crystals. 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 published in Japanese Patent Application Laid-Open No. 52-35.
This is proposed in Publication No. 587. However, those EL
The device has not yet achieved sufficient performance as an actual EL device in terms of brightness, power consumption, etc. Furthermore, in the case of organic EL devices, the density of carrier electrons or holes is extremely low, resulting in problems such as carrier recombination. The probability of excitation of the functional molecule due to this phenomenon 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 above object of the present invention has been achieved by forming a light emitting layer of an EL element by combining specific materials and having a specific configuration.

That is, the present invention provides an EL device comprising a two-layered light emitting layer, a transparent #I electrode layer and a back electrode layer sandwiching the light emitting layer.
In the device, the first light-emitting layer faces the transparent electrode layer and comprises an electroluminescent organic compound (A) and an organic compound relatively electron-accepting to the compound (A) (hereinafter referred to as an acceptor). The second light-emitting layer faces the back electrode layer and is made of an electroluminescent organic compound (A) or the same compound as the compound (A). It is characterized by being composed of a mixed molecule deposited film consisting of a mixture of an electroluminescent organic compound having a certain level of electronegativity and an organic compound relatively electron-donating to compound (A) (hereinafter referred to as donor). This is the above EL element.

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.
It is a compound that calms the electronic system and can be electrically excited. For example, it basically includes fused polycyclic aromatic hydrocarbons, p-terphenyl, 2,5-diphenyl ester, 1,4-
Bis(2-methylstyryl)-benzene, xanthine,
Coumarin, acridine, cyanine dye, benzophenone, phthalocyanine and its metal complex, porphyrin and its metal complex, 8-hydroxyquinoline and its metal complex, organic ruthenium complex, rare earth complex and derivatives of these compounds can be mentioned. can. 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 having a quinone structure, such as tetracyanoquinodimethane and tetracyanoethylene, can be mentioned.

In the present invention, the compound useful for forming the first light-emitting layer is obtained by chemically modifying the electroluminescent compound as described above by a known method as necessary, and having at least one light-emitting layer in its structure. It is a compound that has both a hydrophobic part and at least one hydrophilic part (all of these are in a relative sense), for example, the following general formula (
It includes the compound represented by I) and other compounds.

[(X-R,), Z]TL-)-RL(I) In the above formula, Phosphoric acid 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 amino groups and their salts, hydroxyl groups, etc.; R5 has 4 to 4 carbon atoms;
30, preferably 10 to 25 alkyl groups, preferably linear alkyl groups: m is 1 or a linking group such as "-S O2N R,, -co-1-COO-, etc. (R, is hydrogen (atom, alkyl group, aryl, etc.); φ is a residue of an electroluminescent compound as exemplified later; R1, like X, is a hydrogen atom or any other substituent and at least one of one or more of X, φ and R2 is a hydrophilic moiety, and at least one is a hydrophobic moiety.

In addition, in the present invention, the organic compound useful for forming the second light emitting layer is selected from the same types of compounds as above, except for those chemically modified.

Preferred examples of compounds of general formula (I) useful for forming the first layer, basic skeletons of compounds useful for forming the second layer, and other compounds are as follows. . (However, the following example φ (basic skeleton)
is an alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkyl ether group, a halogen atom, a nido-er group, a primary to tertiary amino group, a hydroxyl group, and a carboxamide group. It may have common substituents such as sulfoamide groups. ) (Hereafter, margin) Z2NH10, s Z-Co, NHZ=Cn, N
Hlo, 5Z=NH,O,5 Z=NH10,S Z=NH,01
Sz=S1Se Z=S1Se Z=
S%Sez = NH, Ols z=NH, αs
Z=N) (, O% S cliff A m Ga% Ir, Ta, a
=3 M=Er, Sm, EuM=Zn, Cd
, P4H, pb, a=2 Gd, Tb,
DyTm%Yb Tb, Dy, Tm1Yb Gd, Tb
, DyTm, Yb Z=O,S, Se 06962 The above luminescent compounds can be used alone in each luminescent layer in the present invention, or can be used as a mixture as long as they have the same electronegativity. Note that these compounds are examples of preferable compounds, and it goes without saying that other derivatives or other compounds may be used as long as the same purpose is achieved.

In the present invention, a luminescent compound (A) having a specific electronegativity or a luminescent compound having a similar electronegativity to the compound (A) is selected from the luminescent compounds as described above, and one EL element of the present invention is prepared. is used as the main emissive compound of the first emissive layer and the second emissive layer of That's what I'm doing.

Among the luminescent compounds or non-luminescent compounds, particularly preferable compounds as acceptors include carbonyl groups,
A compound having an electron-withdrawing group such as a sulfonyl group, a nitro group, or a quaternary amino group. Particularly preferable compounds as a donor include a primary to tertiary amino group, a hydroxyl group, an alkoxy group, an alkyl ether group, etc. The main ones are those that accommodate the electron-donating group of , or nitrogen heterocyclic compounds.

The acceptor as described above is preferably about 1/1 with respect to 1 mole of the luminescent compound forming the first layer as described above.
0 to 1/l O0 mole to reduce the electronegativity of the first layer, and the donor is preferably added in a proportion of about 1/l 0 to
17100 moles to increase the electronegativity of the second layer.

The acceptor as described above may be selected from the above-mentioned luminescent compounds or non-luminescent compounds, or may be selected from other organic compounds with high electron-accepting properties other than those mentioned above.

In addition, the donor may be selected from the above-mentioned luminescent compounds or non-luminescent compounds, or may be selected from other organic compounds with large electron donating properties other than those mentioned above.For example, as the acceptor, the above-mentioned It is preferable to select from various compounds having a substituent having a large electron-accepting property such as those mentioned above, and also, as a donor, from various organic compounds having a substituent having a large electron-donating property as described above.

The other elements forming the EL element of the present invention, namely the transparent electrode layer and the back electrode layer, sandwich the light emitting layer, and
Any conventionally known material can be used, but at least one layer thereof must be transparent. As the transparent electrode layer, any desired transparent electrode layer can be used as in the past, and preferred examples include polymethyl methacrylate,
A transparent conductive material such as indium oxide, tin oxide, indium tin oxide (ITo), etc. is coated on the surface of a transparent film or sheet such as transparent synthetic resin such as polyester, glass, etc. on the entire surface or in a pattern. be. When an opaque back electrode layer is used on one side, these opaque Fi layers may also be of conventionally known types, and generally and preferably have a thickness of about 0.1 to 0.3
It is a vapor deposited film of aluminum, silver, gold, etc. made by JLm. Further, the shape of the transparent electrode layer or the back electrode layer may be any shape such as a plate, a belt, or a cylindrical shape, and can be selected depending on the purpose of use. Further, the thickness of the transparent electrode layer is approximately 0'
, 01 to 0, about 21 Lm is preferable. If the thickness is below this range, the physical strength and electrical properties of the element itself will be insufficient, and if the thickness is above the above range, transparency, lightness, compactness, etc. will be insufficient. There is a risk that problems may occur.

In the EL element of the present invention, between the two electrode layers as described above,
It can be obtained by changing the electronegativity of an electroluminescent compound with a specific electronegativity as described above by adding an acceptor or donor, and forming a luminescent layer consisting of two layers with different electronegativity. A mixture in which the first layer constituting the luminescent layer of the formed two-layer structure faces the transparent electrode layer and is arranged with a highly ordered molecular orientation that is electron-accepting relative to the second layer. It is a monomolecular film or a cumulative film thereof, and is characterized in that the second layer faces the back electrode layer and is a mixed molecular stack VK film that is electron-donating relative to the first layer.

In the present invention, a particularly preferred method for forming such a first layer monolayer or its cumulative VLv 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 Taking advantage of the fact that it forms a monomolecular layer with the functional group facing down,
This is a method of forming a monomolecular film or a cumulative film thereof.

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 OFF is produced in the above manner, a cumulative film of a monomolecular film is formed as a cumulative film having a desired degree of accumulation by repeating the above-mentioned operations.

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 one-turn 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 with a hydrophilic surface is lifted out of water in a direction transverse to the water surface, a monomolecular film with the hydrophilic groups of the molecules facing toward the substrate is formed on the substrate. 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 hydrophilic group and the wood-philic group of the molecule face each other, and the hydrophobic group and the hydrophobic group of the molecule 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 to the substrate H is not limited to these methods,
That is, when using a large-area substrate, a method such as extruding the substrate from a substrate roll into a water layer may also be used. Also,
The directions of the hydrophilic groups and hydrophobic groups described above 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 vapor deposition method, the material is placed in a tungsten board placed in a vacuum chamber, and
If the material is less than m, resistance heating is performed, and if the material is sublimable, the temperature is set to the sublimation temperature, and if the material is meltable, the temperature is set to the melting point or higher. The pre-vacuum level is set to 2 x 10 Tarr or less, the port is closed with a shutter before vapor deposition, the port is heated and the air is allowed to air for 2 minutes, and then the shutter is opened to perform vapor deposition.

The speed in Ti's book is measured while measuring with a crystal oscillator film thickness monitor, but the preferred speed is O1l/sea.
~iooλ/seC. The degree of vacuum at that time is 10 Torr or less, preferably 1 Torr or less, to prevent oxidation etc.
This is done by maintaining the temperature at about 0 Tarr.

In the EL element of the present invention, among the two electrode layers as described above,
As the first layer facing the transparent electrode layer, an electroluminescent compound (A) with a specific electronegativity and an appropriate acceptor are selected from the above compounds to form a mixture, and a mixed monomolecular film or To form the cumulative film and as the second layer facing the back electrode layer, compound (A) from the above compounds or an electroluminescent compound having the same type of electronegativity as compound (A) and a suitable donor are added. It can be obtained by selecting a mixture, forming a mixed molecule deposited film by the method described above, and forming a light-emitting layer into a two-layer structure.

As mentioned in the prior art section, it is known to form an EL element by the LB method, but this known method does not allow for obtaining an EL element with sufficient performance, and the present inventor has conducted various research studies. As a result, the luminescent layer has a two-layer structure, the first luminescent layer is formed as a mixed monomolecular film or a cumulative ffl film thereof using the electroluminescent compound (A) containing the acceptor as described above, and By forming 2N as a mixed molecule deposited film from a donor-containing compound (A) or an electroluminescent compound of the same type of electronegativity as compound (A), the performance of the prior art EL device is significantly improved. This is what we discovered.

One embodiment of the present invention is an embodiment in which the first light-emitting layer is a mixed monomolecular film made of the above-mentioned light-emitting material containing an acceptor. In the EL device of this embodiment, first, a mixture consisting of an electroluminescent compound (A) having a specific electronegativity and an acceptor is dissolved in a suitable organic solvent such as chloroform, dichloromethane, dichloroethane, etc. for about 100 min. ~
16M, and the solution is adjusted to an appropriate pH (e.g., pH about 1 to 8), which may contain various total ions.
) on the aqueous phase, remove the solvent to form a mixed monomolecular film, transfer it to one transparent electrode substrate as the first layer using the LB method as described above, and dry it thoroughly. Then, a second layer is formed as a mixed molecule deposited film using compound A or a mixture consisting of an electroluminescent compound having the same electronegativity as compound (A) and a donor by the above-described molecular deposition method, Next, an electrode material such as aluminum, silver, or gold is deposited on the surface of this second layer, preferably by vapor deposition, to form a back electrode layer.

The thickness of the two-layer light-emitting layer of the EL device thus obtained varies depending on the type of material used, but is generally preferably about 0.01 to 1.0 pm.

Another important aspect is that the first layer constituting the light emitting layer of the EL Hiroko of the present invention is a cumulative film of the above-mentioned mixed monomolecular film. This embodiment can be obtained by using the above-mentioned LB method, by accumulating the above-mentioned mixed monomolecular film by various methods up to the required number of layers, and then forming the first layer as above-mentioned.

The thickness of the light-emitting layer of the EL device of the present invention obtained in this way can be changed arbitrarily, but in the present invention, the cumulative number of mixed monomolecular films in the first layer is about 4 to 200. Preferably, the thickness of the second layer is about 0.01''0.5 gm, and the total thickness of the emissive layer is about 0.02 to Igm.

Note that the adhesion between one or both electrode layers used as a substrate and the light-emitting layer is sufficiently strong in the LB method and molecular deposition method, and the light-emitting layer does not peel or fall off. However, in order to strengthen the adhesive strength, the surface of the substrate may be treated in advance, or an appropriate adhesive layer may be provided between the substrate and the light emitting layer.Furthermore, in the LB method, the light emitting layer The adhesive strength can also be strengthened by adjusting various conditions such as the type of material used for forming the adhesive, the pH of the water layer used, the ion species, the water temperature, the transfer rate of the monomolecular film, or the surface pressure of the monomolecular film.

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 layer has a high degree of molecular order and sensitivity necessary for the operation of an EL device, and the second layer and the first layer have various electrical interactions. By doing so, excellent light emitting performance can be achieved.

Furthermore, as schematically shown in FIG. 1, the light-emitting layer of the EL device of the present invention is different from the light-emitting layer consisting of a single layer in the prior art, as schematically shown in FIG. light emitting layer and second
Since the light-emitting layer has a uniform interface, various interactions between these two layers with different electronegativity are extremely easy, and it exhibits excellent light-emitting performance that cannot be achieved with conventional technology. It is something to do. That is, by variously changing the difference in electronegativity between the first light-emitting layer and the second light-emitting layer, the light emission intensity can be improved or the light emission color can be changed arbitrarily, and the service life can also be changed. It can be significantly extended.

Furthermore, although the conventional technology has excellent luminescence properties, it was virtually impossible to use materials with insufficient film formability or film strength; however, in the present invention, materials with poor film formability or film strength can be used. but,
Even if a material has excellent luminescence properties, by using a material with excellent film-forming properties for one of the layers, a light-emitting layer with excellent luminescence properties, film-forming properties, and film strength can be obtained.

The EL device of the present invention described above can achieve excellent EL performance 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. It shows 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+ am square glass plate by sputtering. After thoroughly cleaning this film-forming substrate, Joyce -
Langmuir-Trough manufactured by Loabe1
Next, (A) (B) and combination compounds (A) and (B) were mixed in a molar ratio of 100:L, which was immersed in an aqueous phase containing 4 After dissolving it in chloroform (10 mol/i), it was developed on the above water phase. After removing the solvent chloroform 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 was gently moved up and down in the direction across the water surface (vertical speed 2 cm/ll1n), the mixed monomolecular film was transferred onto the substrate, and the mixed monomolecular film was accumulated into 6 layers. A monomolecular cumulative film was created. In this accumulation process, each time the substrate was pulled out of the water tank, it was left to stand for 30 minutes or more to evaporate and remove the water adhering to the substrate.

Next, add resistance! Using a vapor deposition apparatus, anthracene
C) (mP, 216°C) and indazole (D) (mp
, 146°C) was deposited to a film thickness of 500 nm. This vapor deposition is performed by first reducing the pressure in the vapor deposition tank to a vacuum level of 10 Torr, and gradually increasing the temperature of the resistance heating board (Mo).
The current flowing through the resistance heating board is kept constant so that the deposition rate of indasol is about 0.2 people/see.
A deposited film was formed by adjusting the current flowing through the board containing anthracene so that the total deposition rate was 2 A/see. The degree of vacuum during vapor deposition was 9×10 Torr. Further, the temperature of the substrate holder was kept constant by circulating 20° C. water.

Finally, t! formed as above! li I? 2 was placed in a vapor deposition tank, the tank was once depressurized to a vacuum level of 10 Torr, the vacuum level was adjusted to 10 Torr, and the vapor deposition rate 2 was reduced.
The EL element prepared by thinly depositing AI' on the thin film with a film thickness of 1500 at 0λ/sec and using it as a back electrode was used as a third electrode.
As shown in the figure, after sealing with seal glass,
Purified, degassed, and dehydrated silicone oil was injected into the seal to form the EL light emitting cell of the present invention according to conventional methods. IOV, 400H for these EL light emitting cells
When an AC voltage of z was applied, the current density was 0.14 mA.
/crn' with a brightness of 26 f t-L.

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

Comparative Example 1 A comparative EL element was obtained in the same manner as in Example 1 except that the second layer was not formed.
Moreover, when evaluated in the same manner as in Example 1, the current density was 0,
18 mA/crrr'te luminance was less than 5ft.

Example 2 In place of compounds A, B, C and D in Example 1, E F G
H Using the above compounds E, F, G and H, and in the same manner as in Example 1, an EL device of the present invention (however, the cumulative number was 6) was obtained, and evaluated under the same conditions as in Example 1. , current density 0, 12 mA/crn', brightness (
Ft-L) was 23.

[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. 1; Transparent electrode 2: Luminescent layer 3; Back electrode 4; Luminescent compound 4' Near acceptor 5; Luminescent compound 5': Donor 6: Seal glass 7; Silicon insulating oil 8 Glass plate Figure 1 Figure 3

Claims (1)

[Claims] In an EL device comprising a two-layered light emitting layer, a transparent electrode layer and a back electrode layer sandwiching the light emitting layer, the first light emitting layer faces the transparent electrode layer and is made of an electroluminescent organic compound. (A) and an organic compound that is relatively electron-accepting to compound (A); facing the electroluminescent organic compound (A) or an electroluminescent organic compound with the same electronegativeness as the compound (A), and an electroluminescent organic compound that is relatively electron donating to the compound (A). The above-mentioned EL device is made of a mixed molecule deposited film made of a mixture of.