JP3045799B2 - Organic electroluminescence device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel organic electroluminescence device. More specifically, the present invention relates to an organic electroluminescent device which has excellent heat resistance, can be manufactured with good yield, and can emit light with high luminance (from blue-green to green) at a low applied voltage.

[0002]

2. Description of the Related Art In recent years, electroluminescent devices (hereinafter abbreviated as EL devices) have high visibility for self-emission, and have characteristics such as excellent impact resistance because they are completely solid devices. Attention has been focused on its use as a light emitting element in various display devices.

The EL element includes an inorganic EL element using an inorganic compound as a light emitting material and an organic EL element using an organic compound. Among these, the organic EL element can greatly reduce the applied voltage. Therefore, research on its practical use has been actively conducted.

[0004] The structure of the organic EL element is based on the structure of anode / light-emitting layer / cathode, and provided with a hole injection / transport layer or an electron injection / transport layer as appropriate, for example, anode / hole injection / transport layer. A structure having a structure such as / emission layer / cathode or anode / hole injection / transport layer / emission layer / electron injection / transport layer / cathode is known. The hole injecting and transporting layer has a function of transmitting holes injected from the anode to the light emitting layer, and the electron injecting and transporting layer has a function of transmitting electrons injected from the cathode to the light emitting layer. I have. By interposing the hole injection transport layer between the light emitting layer and the anode, many holes are injected into the light emitting layer at a lower electric field, and further injected into the light emitting layer from the cathode or the electron injection transport layer. It is known that the emitted electrons increase the luminous efficiency accumulated in the light emitting layer near the interface between the hole injection layer and the light emitting layer when the hole injection layer does not carry the electrons [“Abride Physics”.・ Letters (Ap
pl. Phys. Lett. ) "Vol. 51, pp. 913 (198
7 years)].

As such an organic EL device, for example, (1) anode / hole injection / transport using an aluminum complex of 8-hydroxyquinoline as a material for a light emitting layer and a diamine compound as a material for a hole injection / transport layer. EL device having a structure of layer / light emitting layer / cathode ["Abride Physics Letters (Appl. Phys. Lett.)", Vol. 51, pp. 913 (1987)], and 8-hydroxyquinoline in the emission band. Laminated EL composed of anode / hole injection zone / organic emission zone / cathode using aluminum rust body
Element (JP-A-59-194393), (2) an EL element having a structure of anode / hole injection zone / emission zone / cathode and having an emission zone formed of a host substance and a fluorescent substance (European Patent Publication No. 281381) is known.

[0006] However, the above (1) and (2)
In the L element, although high-luminance light emission is obtained at a low voltage, the 8-hydroxyquinoline Al complex used as a light-emitting material is easily thermally decomposed at a temperature exceeding about 300 ° C. 300 ℃ of evaporation source temperature
It is necessary to keep the temperature below the evaporation temperature, which is lower than or equal to about, and there is a problem that the deposition rate becomes slow and the productivity of the device is inevitably reduced. Further, it is difficult to control the temperature of the evaporation source, and the production is unstable. It should be noted that in the EL devices of (1) and (2), unless the material of the light emitting layer having excellent thin film properties is selected, the devices cannot exhibit high performance.

On the other hand, in the EL device of (2), the host material is one capable of injecting holes and electrons from the outside, for example, 8-hydroxyquinoline as a preferable compound.
As the fluorescent substance, a substance that can emit light in response to recombination of holes and electrons is used. In this case, the injection function that the light-emitting band (light-emitting layer) should have (the function of injecting holes from the anode or the hole injection / transport layer by applying an electric field, and the function of injecting electrons from the cathode or the electron injection / transport layer),
Of the transport function (the function of transporting holes and electrons by an electric field) and the light emitting function (the function of providing a field for recombination of holes and electrons and connecting it to light emission), the injection function,
Since the host substance plays a part of the transport function and the light-emitting function, and the fluorescent substance uses only a part of the light-emitting function, the host substance contains a trace amount (5 mol% or less). The EL element having such a configuration has a capacity of 1 at an applied voltage of about 10V.
With a high luminance of about 000 cd / m ² , it is possible to emit light in the red region from the green region. However, since this EL device usually uses 8-hydroxyquinoline as a host substance, it has the same problems as the EL devices of (1) and (2).

[0008]

SUMMARY OF THE INVENTION The present invention solves such a problem in the conventional organic EL device capable of emitting light with high luminance at a low voltage, and is excellent in heat resistance and thin film forming property, and can be manufactured with good yield. Further, it is an object of the present invention to provide an organic EL device capable of emitting light of high luminance with a low applied voltage.

[0009]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to achieve the above object, and as a result, a benzoxazole derivative having a specific structure has an injection function, a transport function and an indispensable function as a light emitting layer. It has a light-emitting function, and is excellent in heat resistance and thin film forming property, does not cause thermal decomposition during deposition, can form a stable thin film, and hardly generates pinholes when forming a counter electrode (metal). From this, it was found that by using this compound as a light-emitting material, an EL device could be obtained with a high yield, and this EL device could emit light with high luminance when a low voltage was applied. It was completed.

That is, the present invention provides a compound represented by the following general formula (I):

[0011]

Embedded image (Wherein, Ar ¹ and Ar ² are each independently an unsubstituted alkyl
A group; an aryl group, an allyl group, a halogen atom or alcohol
An alkyl group substituted with a xy group; an unsubstituted aryl group;
Alternatively, an alkyl group, an alkoxy group, or a halogen atom
Represents an aryl group substituted with a substituent, and A represents unsubstituted phenyl
Len group; alkyl group, alkoxy group, halogen atom,
A phenylene group substituted by a toro or cyano group;
Replacement biphenylene group; alkyl group, alkoxy group, halo
Bife substituted with a gen atom, nitro group or cyano group
Nylene group; unsubstituted terphenylene group; alkyl group,
With alkoxy, halogen, nitro or cyano groups
A substituted terphenylene group; an unsubstituted naphthylene group;
Alternatively, an alkyl group, an alkoxy group, a halogen atom,
Shows naphthylene groups substituted with nitro or cyano groups.
And R ¹ , R ² , R ³ and R ⁴ are each independently an unsubstituted
Alkyl group substituted with a halogen atom; unsubstituted
An alkoxy group; a halogen atom, an alkoxy group or
An alkoxy group substituted by an ano group; a halogen atom;
Or a hydrogen atom. ) Electroluminescent element emitting layer digits set containing a compound represented by was found to have good performance.

In the above formula (I), examples of the substituted or unsubstituted alkyl groups represented by Ar ¹ and Ar ² include linear, branched or cyclic C 1 to C 12 alkyl groups such as methyl and ethyl. Hydrocarbon, benzyl group, aralkyl group such as phenethyl group, allyl group, olefin group such as crotyl group, methallyl group, halogenated alkyl group such as chloromethyl and trichloromethyl, alkoxyalkyl group such as methoxyethyl and ethoxyethyl, etc. Examples of the substituted or unsubstituted aryl group include phenyl, naphthyl, biphenyl, tolyl, xylyl, and mesityl.
Group, an anisyl group ethoxy group, an ethylphenyl group, a cycloalkyl hexylphenyl group, chlorophenyl group, etc. Kurorunafuchiru group.

Examples of the group which can be substituted for phenylene, naphthylene, terphenylene and biphenylene represented by A include an alkyl group, an alkoxy group, a halogen atom, a nitro group and a cyano group.

The substituted or unsubstituted alkyl group represented by R ¹ , R ² , R ³ or R ⁴ includes a methyl group, an ethyl group, a propyl group, a butyl group, a hexyl group, a chloromethyl group and a trichloromethyl group. And the like.Examples of the substituted or unsubstituted alkoxy group include a methoxy group, an ethoxy group, a methoxyethoxy group, a chloromethoxy group, and a cyanomethoxy group.Examples of the halogen atom include a fluorine atom, a chlorine atom, and a bromine atom. And an iodine atom.

In the EL device of the present invention, the thickness of the light-emitting layer is not particularly limited and may be appropriately selected depending on the situation, but is usually about 5 nm to 5 μm. Also,
The EL device of the present invention has various configurations, but basically has a configuration in which the light emitting layer is sandwiched between two electrodes (anode and cathode), and another layer is interposed as necessary. It should be done. Specifically, (1) anode / light-emitting layer / cathode,
There are (2) anode / hole injection / transport layer / light emitting layer / cathode, and (3) anode / hole injection / transport layer / light emitting layer / electron injection / transport layer / cathode. Note that these EL elements are preferably formed over a supporting substrate.

The light emitting layer in the EL device of the present invention has the following three functions. (I) Injection function A function of injecting holes from the anode or the hole injection transport layer and applying electrons from the cathode or the electron injection transport layer when an electric field is applied. (Ii) Transport function A function to move injected charges (electrons and holes) by the force of an electric field. (Iii) Light-emitting function A function of providing a field for recombination of electrons and holes and linking it to light emission. However, there may be a difference between the ease with which holes are injected and the ease with which electrons are injected, and the transport ability represented by the mobility of holes and electrons may be large or small. Is preferably moved.

In the EL device of the present invention, the compound of the general formula (I) used as a light-emitting material (light-emitting layer) has an ionization energy of 6.0 eV or less. It is easy to inject target holes. The charge affinity is 2.8 eV or more, and if an appropriate cathode metal or cathode compound is selected, electrons can be relatively easily injected. In addition, it has excellent electron and hole transport functions. Further, since the solid-state fluorescence is strong, the ability to convert the excited state of the compound, its aggregate, crystal or the like formed at the time of recombination into light is large.

The substrate which can be used in the EL device of the present invention is preferably a substrate having transparency, and generally, glass, transparent plastic, quartz or the like is applied. As the electrodes (anode, cathode), metals such as gold, aluminum and indium, alloys, mixtures or indium tin oxide (mixed oxide of indium oxide and tin oxide; IT
It is preferable to use a transparent material such as O), SnO ₂ , ZnO or the like. A metal having a high work function or an electroconductive compound is preferable for the anode, and a metal or an electroconductive compound having a low work function is preferable for the cathode. Preferably, at least one of these electrodes is transparent or translucent.

In order to produce the above-mentioned (1) EL device having the constitution of anode / light-emitting layer / cathode, for example, the following procedure may be followed. That is, first, an electrode is formed on a substrate by vapor deposition or sputtering. At this time, the film-like electrode generally has a thickness of 10 nm to 1 μm, particularly 200 nm or less.
It is preferable to increase the transmittance of light emission. Next, a light emitting material (compound of the general formula (I)) is formed on the electrode in a thin film to form a light emitting layer. The light-emitting material can be formed into a thin film by spin coating, casting, vapor deposition, or the like, but vapor deposition is particularly preferable because a uniform film is easily obtained and pinholes are not generated. When a vapor deposition method is employed for thinning a light emitting material, the vapor deposition conditions include, for example, a boat heating temperature of 50 to 400 ° C., a degree of vacuum of 10 ⁻⁵ to 10 ⁻³ Pa,
Deposition rate: 0.01 to 50 nm / sec, substrate temperature: -50 to +
The thickness may be selected to be 5 nm to 5 μm in the range of 300 ° C. After forming this thin film, an EL element is formed by forming a counter electrode with a thickness of 50 to 200 nm by a vapor deposition method or a sputtering method. The conditions for forming the light emitting layer vary depending on the type of the compound of the general formula (I), the target crystal structure of the molecular deposition film, the association structure, and the like, and may vary in various ways.
The boat heating temperature is preferably kept at a temperature at which the compound of the general formula (I) does not decompose.

In order to prepare (2) an EL element having the structure of anode / hole injection / transport layer / light emitting layer / cathode, first, electrodes are formed in the same manner as in the above-mentioned EL element (1), A hole injecting material (hole transporting compound) is thinned on an electrode by an evaporation method to form a hole injecting and transporting layer. The vapor deposition conditions at this time may be in accordance with the vapor deposition conditions for forming the thin film of the light emitting material. Thereafter, in the same manner as in the case of producing the EL element of the above (1), by forming a thin film of a light emitting material and forming the counter electrode, an EL element having the desired configuration of the above (2) is produced. In the EL device having the structure (2), the order of forming the hole injecting and transporting layer and the light emitting layer may be reversed, and the electrode, the light emitting layer, the hole injecting and transporting layer, and the electrode may be formed in this order.

Further, in order to prepare an EL device having the structure of (3) anode / hole injection / transport layer / light emitting layer / electron injection / transport layer / cathode, first, electrodes are formed in the same manner as in the above-mentioned EL device (1). Then, a hole injecting / transporting layer is formed in the same manner as in the EL element of (2), and a thin film of a luminescent material is formed thereon in the same manner as in the case of forming the EL element of (1). Thereafter, the electron injecting material (electron transfer compound) is thinned by an evaporation method to form an electron injecting and transporting layer on the light emitting layer, and finally, as in the case of producing the EL element of (1) above. When the counter electrode is formed, the intended EL device having the above configuration (3) is formed. Here, the hole injection transport layer /
The order of the light emitting layer / electron injection / transport layer was changed to the electron injection / transport layer / light emitting layer / hole injection / transport layer, and the electrode, the electron injection / transport layer, the light emitting layer, the hole injection / transport layer, and the electrode were formed in this order. Is also good.

In the EL device of the present invention, the hole injecting and transporting layer and the electron injecting and transporting layer are not necessarily required, but the presence of these layers further improves the light emitting performance. here,
The hole injection transport layer (hole injection layer) is made of a hole transport compound (hole injection material) and has a function of transmitting holes injected from the anode to the light emitting layer. By sandwiching this layer between the anode of the EL element and the light emitting layer, more holes are injected into the light emitting layer at a low voltage, and the luminance of the element is improved.

The hole transporting compound of the hole injecting / transporting layer used here is disposed between two electrodes to which an electric field is applied, and when holes are injected from the anode, the holes are appropriately formed in the light emitting layer. A compound that can be transmitted to By interposing the hole injection transport layer between the anode and the light emitting layer, many holes are injected into the light emitting layer with a lower electric field. Further, electrons injected from the cathode or the electron injection / transport layer into the light emitting layer improve the luminous efficiency accumulated near the interface in the light emitting layer due to the electron barrier present at the interface between the light emitting layer and the hole layer. . Preferred hole transport compounds here are 10 ⁴ to 10 ⁶ volts / c.
It has a hole mobility of at least 10 ⁻⁶ cm ² volt-second when the layer is placed between electrodes exposed to an electric field of m.
Therefore, preferred examples include various compounds used as a hole charge transporting material in a photoconductive material.

The following examples are given as such charge transport materials. [1] Triazole derivatives described in U.S. Pat. No. 3,121,197, etc., [2] U.S. Pat. No. 3,189
No. 447, oxadiazole derivatives, [3] imidazole derivatives described in JP-B-37-16096, etc., [4] U.S. Pat.
Nos. 5402, 3820989, 3542544, JP-B-45-555, JP-B-51-10983, JP-A-51-93224, and JP-A-51-93224.
No. 105, No. 56-4148, No. 55-108667
Polyarylalkane derivatives described in JP-A Nos. 55-15695 and 56-36656;
[5] US Pat. Nos. 3,180,729 and 4,278,746
And JP-A-55-88064 and JP-A-55-880.
No. 65, No. 49-105537, No. 55-51086
No. 56-80051, No. 56-88141, No. 57-45545, No. 54-112637, No. 55
Pyrazoline derivatives and pyrazolone derivatives described in JP-A-74546, [6] U.S. Pat.
No. 404, JP-B-51-10105, 46-
Nos. 3712, 47-25336, and JP-A-54-53435, JP-A-54-110536, and JP-A-54-53536.
And phenylenediamine derivatives described in JP-A-119925, [7] U.S. Pat. Nos. 3,567,450, 3,180,703, 3,240,597, and 36585.
No. 20, No. 4,232,103, No. 4,175,961 and No. 401,376, and JP-B-49-35702,
JP-A-39-27577 and JP-A-55-14
No. 4250, No. 56-119132, No. 56-224
No. 37, an arylamine derivative described in West German Patent No. 1110518, etc., [8] an amino-substituted chalcone derivative described in US Pat. No. 3,526,501, etc.

[9] Oxazole derivative described in U.S. Pat. No. 3,257,203, [10] Styryl anthracene derivative described in JP-A-56-46234, etc., [11] JP-A-54-11083
7, fluorenone derivatives, [1
2] U.S. Pat. No. 3,717,462 and Japanese Patent Application Laid-Open No. 54-1979.
No. 59143, No. 55-52063, No. 55-520
No. 64, No. 55-46760, No. 55-85495
Hydrazone derivatives described in JP-A Nos. 57-11350 and 57-148749, [13] JP-A Nos. 61-210363, 61-228451, and 6
1-114642, 61-72255, 62-4
No. 7646, No. 62-36674, No. 62-1065
No. 2, 62-30255, 60-93445,
No. 60-94462, No. 60-174747, No. 6
Stilbene derivatives and the like described in JP-A No. 0-175052 and the like can be listed.

A more particularly preferred example is disclosed in
The compound (aromatic tertiary amine) as a hole transport layer and the compound (porphyrin compound) as a hole injection zone disclosed in JP-A-3-295695 can be exemplified.

Further preferred examples of the hole transport compound are described in JP-A-53-27033 and JP-A-54-584.
Nos. 45, 54-149634, 54-6
No. 4299, No. 55-79450, No. 55-
Nos. 144250, 56-119132, 61-295558, 61-98353, and U.S. Pat. No. 4,127,412. Examples of these are as follows.
(Chemical Formulas 3 to 5)

[0027]

Embedded image

[0028]

Embedded image

[0029]

Embedded image A hole injecting and transporting layer is formed from these hole transporting compounds, and the hole injecting layer may be composed of a single layer, or may be formed by laminating a hole injecting and transporting layer using a different compound from the above layer. Good.

On the other hand, the electron injecting and transporting layer (electron injecting layer) is made of a compound that transmits electrons. Preferable examples of the electron transfer compound (electron injection material) for forming the electron injection transport layer include:

[0031]

Embedded image Nitro-substituted fluorenone derivatives such as
No. 149259, No. 58-55450, No. 63-10
No. 4061, anthraquinone dimethane derivatives, Polymer Preprints, Japan Vol. 37, N
O.3 (1988), p. 681 etc.

[0032]

Embedded image Diphenylquinone derivatives such as,

[0033]

Embedded image Thiopyrazine oxide derivatives such as
Pl. Phys., 27, L269 (1988), etc.

[0034]

Embedded image Fluorenylidenemethane derivatives described in JP-A-60-69657, JP-A-61-143664, JP-A-61-148159 and the like; JP-A-61-225151; Examples include anthraquinodimethane derivatives and anthrone derivatives described in gazettes and the like.

The EL device of the present invention having the above structure is
When applying a direct current, the anode has a positive polarity and the cathode has a negative polarity.
Light is emitted when a voltage of 5 to 40 V is applied. Even if a voltage is applied with the opposite polarity, no current flows and no light is emitted. Alternatively, an AC or an arbitrary pulse voltage can be applied. In this case, light is emitted only when the anode has a positive bias and the cathode has a negative bias.

[0036]

Next, the present invention will be described in more detail with reference to examples. Example 1 A glass substrate (25 mm × 75 mm × 1.1 mm, H
OYA Co., Ltd.) was used as a transparent support substrate, which was subjected to ultrasonic cleaning with isopropyl alcohol for 30 minutes, and further immersed in isopropyl alcohol for cleaning. Next, the transparent support substrate was dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation apparatus, and N, N′-bis (3-methylphenyl) -1,1 was placed in a molybdenum resistance heating boat. Add 200 mg of '-biphenyl-4,4'-diamine (TPD), and add the following formula (1) to another molybdenum resistance heating boat.

[0037]

Embedded image Was placed in a vacuum evaporation apparatus. After this,
The pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, the boat containing the TPD was energized and heated to 220 ° C., and the deposition rate was set to 0.1.
Deposited on a transparent support substrate at a rate of ~ 0.3 nm / sec.
nm as a hole injection layer (hole injection transport layer). further,
The boat containing the above (1) was energized, heated to 215 ° C., and vapor-deposited on the hole injection layer on the transparent support substrate at a vapor deposition rate of 0.1 to 0.3 nm / sec. Was obtained. The temperature of the substrate during vapor deposition was room temperature. Then, a vacuum chamber was opened, a stainless steel mask was placed on the light-emitting layer, 1 g of magnesium was placed in a molybdenum resistance heating boat, and 1 copper was placed in a crucible of an electron beam evaporation apparatus.
Then, the pressure in the vacuum chamber was reduced to 3 × 10 ⁻⁴ Pa again. Thereafter, electricity was supplied to the boat containing magnesium, and magnesium was deposited at a deposition rate of 4 to 5 nm / sec. At this time, at the same time, the copper is heated by the electron beam, and the copper is heated to 0.2 to 0.1.
Copper was vapor-deposited at 3 nm / sec, and the magnesium was mixed with copper to form a counter electrode. Thus, the manufacture of the EL element was completed. When an ITO electrode of this device was used as a positive electrode and a counter electrode made of a mixture of magnesium and copper was used as a negative electrode, when a direct current of 20 V was applied, a current having a current density of 21 mA / cm ² flowed, and blue light emission was obtained.

Example 2 A glass substrate (25 mm × 75 mm × 1.1 mm, H
OYA Co., Ltd.) was used as a transparent support substrate, which was subjected to ultrasonic cleaning with isopropyl alcohol for 30 minutes, and further immersed in isopropyl alcohol for cleaning. Next, this transparent support substrate was dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation apparatus, 200 mg of TPD was placed in a molybdenum resistance heating boat, and the following formula was added to another molybdenum resistance heating boat. (2) (Formula 11)

[0039]

Embedded image 200 mg was put in the vacuum evaporation apparatus. Thereafter, the pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, the boat containing the TPD was energized and heated to 220 ° C., and the vapor deposition rate was 0.1 to 0.1 Pa.
Deposited on a transparent support substrate at 0.3 nm / sec.
m of the hole injection layer (hole injection transport layer). Further, the boat containing the above (2) was energized, heated to 210 ° C., and deposited on the hole injection layer on the transparent support substrate at a deposition rate of 0.1 to 0.3 nm / sec. A light emitting layer having a thickness of 80 nm was obtained. The temperature of the substrate during vapor deposition was room temperature. Then, a vacuum chamber was opened, a stainless steel mask was placed on the light-emitting layer, 1 g of magnesium was placed in a molybdenum resistance heating boat, and 1 copper was placed in a crucible of an electron beam evaporation apparatus.
Then, the pressure in the vacuum chamber was reduced to 3 × 10 ⁻⁴ Pa again. Thereafter, electricity was supplied to the boat containing magnesium, and magnesium was deposited at a deposition rate of 4 to 5 nm / sec. At this time, at the same time, the copper is heated by the electron beam, and the copper is heated to 0.2 to 0.1.
Copper was vapor-deposited at 3 nm / sec, and the magnesium was mixed with copper to form a counter electrode. Thus, the manufacture of the EL element was completed. When an ITO electrode of this element was used as a positive electrode and a counter electrode made of a mixture of magnesium and copper was used as a negative electrode, a current of 13 mA / cm ² flowed when a direct current of 14 V was applied,
Blue emission was obtained.

Example 3 A glass substrate (25 mm × 75 mm × 1.1 mm, H
OYA Co., Ltd.) was used as a transparent support substrate, which was subjected to ultrasonic cleaning with isopropyl alcohol for 30 minutes, and further immersed in isopropyl alcohol for cleaning. Next, this transparent support substrate was dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation apparatus, 200 mg of TPD was placed in a molybdenum resistance heating boat, and the following formula was added to another molybdenum resistance heating boat. (3) (Chemical formula 12)

[0041]

Embedded image Was placed in a vacuum evaporation apparatus. After this,
The pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, the boat containing the TPD was energized and heated to 220 ° C., and the deposition rate was set to 0.1.
Deposited on a transparent support substrate at ~ 0.3 nm / sec.
nm as a hole injection layer (hole injection transport layer). further,
The boat containing the above (3) is energized, and 230 to 235
C. and heated at a deposition rate of 0.1 nm / sec to deposit on the hole injection layer on the transparent support substrate to obtain a light emitting layer having a thickness of 80 nm. The temperature of the substrate during vapor deposition was room temperature. afterwards,
Open the vacuum chamber, place a stainless steel mask on the light emitting layer, put 1 g of magnesium in a molybdenum resistance heating boat, and put 100 g of copper in the crucible of the electron beam evaporation apparatus.
g, and the pressure in the vacuum chamber was reduced to 3 × 10 ⁻⁴ Pa again. After that, the boat containing magnesium was energized and the deposition rate was 4
Magnesium was deposited at ５5 nm / sec. At this time, the copper is simultaneously heated by an electron beam,
Copper was vapor-deposited in seconds, and copper was mixed with the magnesium to obtain a counter electrode. Thus, the manufacture of the EL element was completed. When a direct current of 17 V was applied using an ITO electrode as a positive electrode and a counter electrode made of a mixture of magnesium and copper as a negative electrode, a current having a current density of 194 mA / cm ² flowed, and green light was emitted.

Example 4 A glass substrate (25 mm × 75 mm × 1.1 mm, H
OYA Co., Ltd.) was used as a transparent support substrate, which was subjected to ultrasonic cleaning with isopropyl alcohol for 30 minutes, and further immersed in isopropyl alcohol for cleaning. Next, the transparent support substrate is dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation apparatus, and placed in a molybdenum resistance heating boat by the following formula (4).

[0043]

Embedded image Was placed in a vacuum evaporation apparatus. afterwards,
The pressure in the vacuum chamber was reduced to 2 × 10 ⁻⁴ Pa, the boat containing (4) was energized, heated to 210 to 220 ° C., and vapor-deposited on the transparent support substrate at a vapor deposition rate of 0.3 nm / sec. Thick 3
A light emitting layer of 00 nm was obtained. The temperature of the substrate during vapor deposition was room temperature. Then, a vacuum chamber was opened, a stainless steel mask was placed on the light-emitting layer, 1 g of magnesium was put into a molybdenum resistance heating boat, 100 g of copper was put into a crucible of an electron beam evaporation apparatus, and the vacuum tank was again set to 3 mm. × 10 ^-4
The pressure was reduced to Pa. Thereafter, electricity was supplied to the boat containing magnesium, and magnesium was deposited at a deposition rate of 4 to 5 nm / sec. At this time, simultaneously heat the copper with the electron beam,
Copper was vapor-deposited at a rate of 0.2 to 0.3 nm / sec, and copper was mixed with the magnesium to obtain a counter electrode. Thus, the manufacture of the EL element was completed. A current density of 180 mA / cm was obtained by applying a DC voltage of 19 V with the ITO electrode of this device as a positive electrode and the counter electrode made of a mixture of magnesium and copper as a negative electrode.
Current ² flowed and green light was emitted.

[0044]

According to the present invention, in an electroluminescence element, a thin film containing a benzoxazole derivative having a specific structure is used for a light emitting layer.
An electroluminescent element having excellent heat resistance and thin film forming properties and high luminous efficiency can be provided.

Claims (1)

(57) [Claims] 1. A structure in which a light emitting layer and a hole transporting layer made of an organic compound and stacked on each other are disposed between a cathode and an anode, and the light emitting layer is represented by the following general formula (I). An electroluminescent device comprising a compound. Embedded image (Wherein, Ar ¹ and Ar ² are each independently an unsubstituted alkyl
A group; an aryl group, an allyl group, a halogen atom or alcohol
An alkyl group substituted with a xy group; an unsubstituted aryl group;
Alternatively, an alkyl group, an alkoxy group, or a halogen atom
Represents an aryl group substituted with a substituent, and A represents unsubstituted phenyl
Len group; alkyl group, alkoxy group, halogen atom,
A phenylene group substituted by a toro or cyano group;
Replacement biphenylene group; alkyl group, alkoxy group, halo
Bife substituted with a gen atom, nitro group or cyano group
Nylene group; unsubstituted terphenylene group; alkyl group,
With alkoxy, halogen, nitro or cyano groups
A substituted terphenylene group; an unsubstituted naphthylene group;
Alternatively, an alkyl group, an alkoxy group, a halogen atom,
Shows naphthylene groups substituted with nitro or cyano groups.
And R ¹ , R ² , R ³ and R ⁴ are each independently an unsubstituted
Alkyl group substituted with a halogen atom; unsubstituted
An alkoxy group; a halogen atom, an alkoxy group or
An alkoxy group substituted by an ano group; a halogen atom;
Or a hydrogen atom . )