JPS6143682A - El element - Google Patents

Abstract

PURPOSE:To provide an EL element emitting luminescence in high luminance even at a low voltage, and producible easily at a low cost, by sandwiching a luminescent layer composed of a mixed monomolecular film consisting of an electron-accepting luminescent substance, etc., and a mixed built-up film consisting of an electron-donative luminescent substance, with a transparent electrode and a back electrode. CONSTITUTION:The first luminescent layer placed opposite to the transparent electrode layer 1 is made of a mixed monomolecular film or its built-up film composed of a mixture of an electroluminescent compound 4 having higher electron affinity than the second luminescent layer and an organic compound 4' having higher electron affinity than the compound 4. The second luminescent layer is placed opposite to the back electrode layer 3, and is made of a mixed built-up film composed of a mixture of an electroluminescent organic compounds having higher electron donative property than the first luminescent layer and an organic compound 5' having higher electron donative property than the organic compound 5. The objective EL element can be manufactured by sandwiching the double-layered luminescent layer 2 with the transparent electrode 1 and the back electrode 3.

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,
S of at least one electroluminescent organic compound, each layer having a different electronegativity relative to the other adjacent layers.
The present invention relates to an EL element made of a film.

(Prior art) Conventional EL elements are made of Mn, Cu or Re F3.
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 thin II! In EL, a light emitting layer is formed by vaporizing a light emitting base material on a substrate, so it is difficult to manufacture a large area device, and the manufacturing cost is extremely 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, when 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 type of element in which an intermediate dielectric layer made of a vinylidene fluoride polymer is disposed within the light emitting layer of the powder type EL has been disclosed in JP-A-58-172891.
Although sufficient performance in terms of luminance and power consumption has not yet been achieved, recent research and development efforts have been actively conducted to control the chemical structure and higher-order structure of organic materials to create new materials for optical and electronics applications. EC element,
Organic materials, such as piezoelectric elements, pyroelectric elements, nonradiometric 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 visiting conductors and pyrene derivatives, which have a parent tree group and a hydrophobic group in the molecule, has been developed. The EL element formed on the electrode substrate was disclosed in Japanese Patent Application Laid-Open No. 52-35587.
It is proposed in the Publication No. but.

Those EL elements are different from the real E in terms of brightness, power consumption, etc.
It has not yet achieved sufficient performance as an L element, and furthermore,
In the case of the organic EL device, the density of carrier electrons or holes is very low, and the probability of excitation of organic molecules due to carrier recombination is very small, so that efficient light emission cannot be expected.

(Disclosure of the Invention) Therefore, the purpose of Kippatsu 11 is to solve the above-mentioned drawbacks of the prior art, 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. The goal is to provide the following.

The above object of the present invention was achieved by forming the light emitting layer of an EL element by combining specific materials and having a specific configuration.

That is, the present invention 1 is an EL device consisting of a two-layered light emitting layer, a transparent 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 includes an electroluminescent organic compound that is electron-accepting relative to the second light-emitting layer and an electroluminescent organic compound that is electron-accepting relative to the second light-emitting layer. the second light-emitting layer faces the back electrode layer and is relatively electron-donating to the first light-emitting layer; The above-mentioned EL device is characterized in that it is composed of a mixed molecular structure consisting of a mixture of an electroluminescent organic compound having an electroluminescent property and an organic compound having an electron donating property relative to the compound.

To explain the present invention in detail, 1. 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 has an electronic system and can be electrically excited. For example, it basically includes fused polycyclic aromatic hydrocarbons, p-terphenyl, 2.5-diphenyloxazole, 1.4-
Bis(2-methylstyryl)-benzene, xanthine,
Coumarin, acridine, cyanine dye, benzophenone, phthalocyanine and its metal complex, porphyrin and its gold m20 form, 8-hydroxyquinoline and its metal complex, organic ruthenium complex, organic rare earth complex, and derivatives of these compounds, etc. I can do it. 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. In the present invention, the compound useful for forming the first light emitting layer is an electroluminescent compound as shown in -1= by a known method if necessary. Chemically modified.

It is a compound that has at least one hydrophobic part and at least one woody part (both of which are in a relative sense) in its structure.
For example, the compound represented by the following general formula (I) and other compounds are included.

C(X −R,), rLZ ],, −φ−R2(I )
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, a silicate group, a 1-3 amino group; a metal salt thereof; Primary to tertiary amine salt, acetic acid salt; ester group, sulfamide group, amide group, imino group, quaternary terimino group and their salts, water group, etc.; R1 is carbon a4 to 30, preferably 10 to 25 alkyl groups,
Preferably a linear alkyl group; m is 1 or 2,
n is an integer from 1 to 4; Z is a direct bond or -'S O
2N R3, -GO-1-〇〇〇- etc.
3 is an arbitrary substituent such as a hydrogen atom, an alkyl group, or an aryl group; φ is a residue of an electroluminescent compound as exemplified later; R2 is a hydrogen atom or any other arbitrary substituent, like X at least one of one or more of X, φ and R2 is a hydrophilic moiety, and at least one is a hydrophobic moiety.

Furthermore, in the present invention, organic compounds useful for forming the light-emitting layer of fJS2 are selected from the same types of compounds as described above, except for those chemically modified.

Preferred examples of compounds of general formula CI) useful for forming the first layer, basic skeletons of compounds useful for forming the second layer, and other compounds are as follows. (However, φ ( ], single skeleton) illustrated below is an alkyl group having 1 to 4 carbon atoms, an alkoxy group, an alkyl ether group, a halogen atom, a nitro group, 1 to 3 carbon atoms
It may have general substituents such as a grade amino group, a hydroxyl group, a carboxamide group, a sulfoamide group, etc. ) Below C Margin ) Z=NH,O,S Z=CO,NHZ=CO,NH
, O%5Z=NH%0, S z = NH, OlS Z=N
H,01SZ=S% Se Z=Ss S
e Z=Ss SeZ=NH,O,
S Z=NH, Q S Z=N) f, O, SM
=Mg, Zn5SnsALCL M=Hz, Be
, Mg, Ca, CdSn, AtC1%YbCI M = Er, Trr4 Sm, Eu, Tb,
Z=0, HAu M≠Am Gas Ir* Tab a=3 M
=Er, Sm, EuM=ZniC(ItMg*
p b + a=2 Gd s Tb s
D yTm%Yb Tb, Dy, 1'm, Yb Gd,
Tb, DyTm, Yl) Z"Os S, Se 05152 The above luminescent compounds can be used alone or as a mixture in each luminescent layer in the present invention.
These compounds are examples of preferred compounds, and it goes without saying that other derivatives or other compounds may be used as long as the same purpose is achieved.

The present invention is characterized in that the luminescent compounds as described above are used separately in the first luminescent layer and the second luminescent layer of the EL device of the present invention, depending on their electronegativity. That is, since the above-mentioned luminescent compounds have different electronegativities, among them, the compound that is relatively electron-accepting is selected as the luminescent compound for forming the first luminescent layer. However, a surface photo likely compound which is electron-donating relative to these compounds may be selected as the compound for forming the second light-emitting layer.

Among such luminescent compounds, particularly preferable electron-donating compounds are those having electron-withdrawing groups such as primary to tertiary amino groups, hydroxyl groups, alkoxy groups, alkyl ether groups, or nitrogen-donating compounds. Heterocyclic compounds are the main ones, and the electron-accepting ones are mainly compounds having electron-withdrawing groups such as carbonyl groups, sulfonyl groups, nidros (and quaternary amine 7 groups). In the present invention, such luminescent compounds can be used alone or in combination in each luminescent layer.

The present invention further preferably includes an organic compound (hereinafter referred to as an acceptor) that is relatively more electron-accepting than the luminescent compound forming the first layer as described above, preferably about In addition, in a proportion of 1/10 to 1/100 mol, the electron-accepting property of the first compound is further strengthened, and the electron-donating property is added to the luminescent compound forming the second compound relative to that of the compound. The organic compound (hereinafter referred to as donor) is preferably used in an amount of about 1/10 to
In addition in a proportion of 1/100-mole, t52. It is characterized by further strengthening the electron-donating properties of the compound.

The acceptor as described above may be selected from the above-mentioned luminescent compounds, or may be selected from other organic compounds with large electron-withdrawing properties other than the above-mentioned, and the donor may also be selected from the above-mentioned luminescent compounds. For example,
The acceptor is selected from various compounds having a large electron-withdrawing substituent as mentioned above, and the donor is selected from various organic compounds having a large electron-donating substituent as mentioned above. be able to.

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, or indium tin oxide (ITo) is coated on the surface of a transparent film or sheet such as a transparent synthetic resin such as polyester or glass, etc., either completely or in a turn shape. It is something. When an opaque back electrode layer is used on one side, these opaque electrode layers may also be conventionally known ones, and generally and preferably have a thickness of about 0.1 to 0.3
It is a 4m long vapor deposited film of aluminum, silver, gold, etc. 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 cylinder, and can be selected depending on the purpose of use. Further, the thickness of the transparent electrode layer is approximately 0
．． For O1 to 0.2 m, it 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, it will not be transparent, lightweight, or compact. 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 is obtained by forming a luminescent layer consisting of two layers using separately the electroluminescent compounds (containing acceptor or donor) having relatively different electronegativities as described above, and the formed The first layer constituting the two-layer structure light-emitting layer faces the transparent electrode layer, and is made of a compound that is electron-accepting relative to the second layer, and is composed of mixed monomolecules arranged with highly ordered molecular orientation. membrane or its accumulation a
membrane, the second layer facing the back electrode layer and comprising a compound that is electron-donating relative to the first layer. It is characterized by being

In the present invention, a particularly preferred method for forming such a twelfth monomolecular film or a cumulative film thereof is the Langmuir-Zolojet method (CLB method). When the balance between the two groups (amphiphilic balance) is maintained at an appropriate level in a molecule with a structure having a group and a hydrophobic group, the molecule forms a single molecule on the water surface with the woody group facing downward. This method utilizes the formation of layers to form a monomolecular film or a cumulative film thereof.

Specifically, to prevent the monomolecular film spread on the water layer from freely diffusing and spreading too much, a partition plate (or float) was installed to limit the spread area and to Gradually increase the surface pressure by controlling the quality aggregation state, and set the surface pressure suitable for manufacturing a monomolecular film or its cumulative film.While maintaining this surface pressure, gently raise the clean substrate directly to 1. A monomolecular film is transferred onto the substrate by lowering or dropping the monomolecular film.Although the monomolecular film is manufactured by the above steps, the cumulative film of the monomolecular film can be formed by repeating the above operation to form a cumulative film with a desired degree of accumulation. It is formed.

In addition to the above-mentioned vertical dipping method, the monomolecular film can be transferred to the substrate by methods such as the horizontal dipping method and the 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 vertical immersion method described above, when a substrate with a hydrophilic surface is lifted out of water in a direction transverse to the water surface, a single molecule 11Q is formed on the substrate, with the molecule's tree-philic group facing toward the substrate.

As mentioned above, when the substrate is lowered one step, the monomolecular film becomes thinner one by one in each process.The direction of the film-forming molecules is reversed in the lifting process and the dipping process, so this method Between the layers are the hydrophilic groups of the molecule and the hydrophobic groups of the molecule), (
A Y-shaped film is formed in which the and hydrophobic groups 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. The cumulative film with the hydrophilic groups facing the substrate is called an X-type film.The zero-rotation cylinder method is a method in which a monomolecular film is transferred to the surface of the substrate by rotating the cylinder over 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 salt 81 film constituting the second light-emitting layer include resistance heating vapor deposition and CVD, for example.

With the vapor deposition method, a thin film with a thickness of about 500λ can be formed as the second light emitting layer.

For example, when using the resistance heating vapor deposition method, the material is placed in a tungsten board placed in a vacuum chamber, and the material is placed 30 cm from the substrate.
Otherwise, resistance heating is performed, and sublimable materials are set at the sublimation temperature, and meltable materials are vapor deposited at a temperature higher than the melting point. The pre-vacuum level is set to 2×10 Torr or less, and the boat is closed with a shutter before vapor deposition. After heating the boat and letting it air for 2 minutes, the shutter is opened and vapor deposition is performed.

The speed during vapor deposition is measured while using a crystal oscillator film thickness monitor, but a suitable speed is 0°1λ/sec~
The vacuum level is 10 Torr or less, preferably 10 Torr or less in order to prevent oxidation etc.
This is done by maintaining the pressure at about Torr.

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, select a relatively electron-accepting compound from the above compounds and a suitable acceptor to make a mixture, and form a mixed monomolecular film or a cumulative film thereof by, for example, the LB method. Then, as a second layer facing the back electrode layer, a relatively electron-donating compound and an appropriate donor are selected from the above compounds to form a mixture, and a mixed molecule deposited film is formed by the method described above. However, it can be obtained by forming the light emitting layer into a two-layer structure.

As described in the section of the prior art, it is known to form an EL element by the LB method, but with this known method, an EL element with sufficient performance cannot be obtained.

As a result of various researches, the present inventor made one light-emitting layer into a two-layer structure,
The first luminescent layer is formed as a mixed monomolecular film or a cumulative film thereof using a relatively electron-accepting compound containing an acceptor as described above, and the second M is a donor relative to the first M. EI of the prior art by forming a mixed molecular compound from relatively electron-donating compounds containing EI.

It was discovered that the performance of the device was significantly improved.

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. This embodiment of the EL element is as follows.

First, a mixture of a material that is relatively electron-accepting to the second layer and seven receptors is dissolved in a suitable organic solvent, such as chloroform, dichloromethane, dichloroethane, etc., at a concentration of about 10 to 10-2M. dissolved in a concentration of
The solution is treated with a suitable p-oxide which may contain various metal ions.
H (eg, pH about 1-8) on an aqueous phase and evaporate the solvent to form a mixed monolayer, using the LB method as described above.

Transfer one of the transparent electrodes to a plate and serve as the first layer.
After sufficient drying, a mixture of a material and a donor that is relatively electron-donating to the first layer formed in this way is then deposited as a second mixed molecule deposited film by the molecular deposition method as described above. This is obtained by forming a back electrode layer on the surface of this second layer, and then depositing an electrode material such as aluminum, lR1 gold, etc., preferably by l/A vapor deposition, on the surface of this second layer.

The thickness of the two-layer light-emitting layer of the EL element prepared in this way (1#) varies depending on the type of material used, but
Generally a thickness of about 0.001-1p is preferred.

Another important aspect is that the first layer constituting the light emitting layer of the EL device of the present invention is a cumulative film of the above mixed monomolecular film. In this embodiment, by using the above LB method, the above mixed monomolecular H! can be obtained by accumulating up to the required number of calendars in various ways and then forming tjS2 G as described above.

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. , the thickness of the 21st fJ is approximately 0.01-0.5 gm, and the thickness of the entire light-emitting layer is preferably approximately 0.02-1 gm.

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 adhesion, 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 adhesive strength can be improved by adjusting various conditions such as the type of material for forming the light emitting layer, 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 small fraction F It2. can be strengthened.

Since the performance of the EL element formed as described above may deteriorate due to the influence of moisture and oxygen in the air, it is made moisture resistant by conventionally known means.

It is desirable that the EL device of the present invention has a sealed structure that is resistant to elements.The structure of the light-emitting layer of the EL device of the present invention is an ultra-thin film, and the first layer has a highly resistant sealing structure that is necessary for the operation of the EL device. It has molecular order and function, and exhibits excellent light-emitting performance due to various electrical interactions between the second layer and the first layer.

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 of the prior art which is a single layer, 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. In other words, 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 its durability can be improved. Lifespan can also 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 emission 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 that.

Next, the present invention will be explained in more detail with reference to Examples. Note that 11 parts is based on weight.

Example 1 An ITO layer with a thickness of 1500 Å was deposited on the surface of a 50 m glass plate with a zero angle of entry by sputter-linda method.

A transparent electrode was formed. After thoroughly cleaning this film-forming substrate, Jo
2ce -Langmiur-T manufactured by Loebe1
(A) (B) The above compounds (A) and (B) were added to chloroform in a molar ratio of 10:1. (10 mol/JL), and then poured onto the aqueous phase. After the solvent chloroform was removed by evaporation, the surface pressure was increased (30 dtne/cm) to precipitate the above-mentioned 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 am/sin), and the mixed monomolecular film was transferred onto the substrate, and the mixed monolayer was deposited in five 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 moisture attached to the substrate.

Next, using a resistance heating evaporation device, anthracene (B
) (mp, 216°C) and anthraquinone (D) (mp
, 28s°C) was deposited to a film thickness of 500λ. This vapor deposition is carried out 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). A deposited film was formed by adjusting the current flowing through the board containing anthracene so that the current flowing through the board was kept constant and the total deposition rate was 5 A/sec. The degree of vacuum during vapor deposition was 9 x 10-' Torr. Further, the temperature of the substrate holder was kept constant by circulating 20° C. water.

Finally, the thin film formed as described above was placed in a vapor deposition tank, and the nuclide was depressurized to a vacuum level of -1110 Torr.
The vacuum level was adjusted to 10-5 Torr and the deposition rate was 20λ/s.
EC was used to deposit Al on the thin film to a thickness of 1500^ and use it as a back electrode.The fabricated EL element was sealed with a sealing glass as shown in Figure 3, and then purified and purified according to conventional methods. Degassed and dehydrated silicone oil was injected into the seal to form the EL light emitting cell of the present invention.

When an AC voltage of IOV and 400 Hz was applied to these EL light emitting cells, they exhibited EL light emission with a brightness of 24 ft-L at a current density of 0 and 10 mA/ci+.・The above-mentioned EL device of the present invention is an EL device using ZnS as a luminescent matrix in the conventional example.
E with lower driving voltage and better luminance characteristics than other elements
It was an L element.

Comparative Example 1 A comparative E'L element was obtained in the same manner as in Example 1 except that the second layer was not formed, and evaluated in the same manner as in Example 1. , current density 0
, 1 mA/cm'ffi luminance 1 ft-[.

It was below.

Example 2 In place of the compounds A, B, C and D in Example 1, E When an element (accumulated number: 5) was obtained and evaluated under the same conditions as in Example 1, the luminance (Ft-L) was 30 at a current density of 0.12 A/cm.

[Brief explanation of the drawing]

Figure m1 diagrammatically shows an EL element according to the prior art LB method, Figure 2 diagrammatically shows an EL element according to the present invention, and Figure 3 diagrammatically depicts an EL element 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'; Acceptor 5 Diluminescent compound 5': Donor 6
: Seal glass 7; Silicone insulating oil 8; Glass plate patent applicant Canon Co., Ltd. agent Patent attorney Tera 1) Katsuhiro Yun (C・IX)

Claims (1)

[Claims] In an EL device consisting of 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 the second light-emitting layer faces the second light-emitting layer. The second light-emitting layer is composed of a mixed monomolecular film or a cumulative film thereof consisting of a mixture of an electroluminescent organic compound that is relatively electron-accepting to the compound and an organic compound that is relatively electron-accepting to the compound. is a mixture of an electroluminescent organic compound that faces the above-mentioned back electrode layer and is electron-donating relative to the first light-emitting layer, and an organic compound that is electron-donative relative to the compound. The above-mentioned EL device is made of a mixed molecule deposited film consisting of: