JPH04103688A - Organic electroluminescence element - Google Patents

Abstract

PURPOSE:To obtain the subject new element capable of emitting light having orange color or longer wavelength in high luminance, enabling multi-colored light emission and having improved visibility by using a specific distyrylpyrazine derivative as a light-emitting material. CONSTITUTION:The objective element contains a distyrylpyrazine derivative of formula (at least one of Ar<1> and Ar<2> is a univalent group composed of an aromatic ring having >=4 unsaturated 6-membered rings and the remainder is a univalent group composed of an aromatic ring having >=3 unsaturated 6-membered rings). Preferably, the double bond of the derivative has trans- structure and the substituent is alkyl or alkoxy.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a novel organic electroluminescent device, more specifically, a novel organic electroluminescent device, which is suitable as a light emitting device for various display devices.
Depending on the conditions, the emission of orange color and longer wavelengths can be as low as 1o.
The present invention relates to an organic electroluminescent device that can output at high luminance of oOcd/m' or more, can be multicolored, and has improved visibility.

[Prior Art] In recent years, electroluminescent elements (hereinafter abbreviated as EL elements) have become highly visible due to their self-luminescence, and are completely solid-state elements, so they have characteristics such as excellent impact resistance. Its use as a light emitting element in various display devices is attracting attention.

There are two types of EL devices: inorganic EL devices that use inorganic compounds as light-emitting materials and organic EL devices that use organic compounds. Research on its practical application is actively being conducted.

The structure of the organic EL element is basically an anode/emitting layer/cathode structure, with a hole injection transport layer or an electron injection transport layer provided thereon as appropriate, for example, an anode/hole injection transport layer/emissive layer. Structures such as /cathode, anode/hole injection/transport layer/light emitting layer/electron injection/transport layer/cathode are known.

The hole injection transport layer has a function of transmitting holes injected from the anode to the light emitting layer, and the electron injection transport layer has a function of transmitting electrons injected from the cathode to the light emitting layer. There is. By interposing the hole injection transport layer between the light emitting layer and the anode, many holes are injected into the light emitting layer with a lower electric field, and furthermore, holes are injected into the light emitting layer from the cathode or the electron injection transport layer. Since the hole injection transport layer does not transport electrons, it is known that the electrons accumulated at the interface between the hole injection transport layer and the light emitting layer increase the luminous efficiency [Applied Physics Letters (Appl. , Phys., L.
ett,) J Volume 51, Page 913 (1987)
].

Various organic EL devices have been developed so far, such as (1) TO/triphenylamine derivative/8 in which a triphenylamine derivative is used as a hole injection transport layer and an 8-hydroxyquinoline All complex is used as a light emitting layer. -Organic EL devices composed of Al complex of hydroxyquinoline/Mg:In [Applied Physics Letters J Vol. 51, p. 913 (1987)], (2) An organic EL element having a multilayer structure similar to the above (1) and using a perylene derivative or a phthaloperinone derivative in the light emitting layer ["Flat Panel Display" published by Nikkei BP, November 1, 1989, No. 91] Pages and cited references], etc. are reported.

However, in the element (1) above, the luminance is 1000 cd/m at a low voltage below IOV! Although the above green light emission can be obtained, light emission with a wavelength longer than orange cannot be obtained, and in the device (2), using a perylene derivative in the light emitting layer produces red light emission, and using a phthalobenone derivative produces yellow light emission. can be obtained with a certain degree of high luminance, but high luminance of 1000 c d/m' or more cannot be obtained in a wide range of orange and red regions.

Furthermore, the present inventors have previously discovered an organic EL element with a light-emitting layer made of a distyrylpyrazine derivative that can provide yellow and green light emission at a high luminance of several hundred cd/m' (patent application No. 1-75936), this element cannot emit orange light or wavelengths longer than this.

As described above, in the conventional organic EL elements, the reality is that high-intensity orange light emission and longer wavelength light have not yet been obtained.

[Problem to be Solved by the Invention 1] Under these circumstances, the present invention is capable of outputting orange and longer wavelength light with high brightness, is multicolored, and has high visibility. The purpose of this invention is to provide an organic EL device with improved properties.

[Means for Solving the Problems] As a result of intensive research to develop an organic EL device having the above-mentioned characteristics, the present inventors found that by using a specific distyrylpyrazine derivative as a luminescent material, We have found a way to achieve the objective, and based on this knowledge, we have completed the present invention.

In other words, the present invention provides a luminescent material that uses a monovalent group consisting of an aromatic ring, at least one of which has four or more unsaturated six-membered rings. and the remainder is a monovalent group consisting of an aromatic ring having three or more unsaturated six-membered rings, which may be the same,
The present invention provides an organic EL device characterized by using a distyrylpyrazine derivative represented by the following formulas (which may be different from each other).

The present invention will be explained in detail below.

In the EL device of the present invention, a compound having a distyrylpyrazine skeleton represented by the above formula (I) is used as a luminescent material. This material exhibits fluorescence in the solid state and provides mobility for electrons and holes.Due to the conjugated nature of the distyrylpyrazine skeleton, it has low ionization energy and high electron affinity, so it removes charges from electrodes, etc. It has characteristics such as easy injection.

Ar' and Ar'' in formula (I) above are monovalent groups, at least one of which is an aromatic ring having four or more unsaturated six-membered rings, and the remaining are monovalent groups having three or more unsaturated six-membered rings. A monovalent group consisting of an aromatic ring having three or more unsaturated six-membered rings, which may be the same or different. Examples of the group include aromatic residues such as evanthonyl group, pyrenyl group, perylenyl group, and benzanthranyl group.These aromatic residues may be substituted with various substituents as long as the above-mentioned properties are not impaired. Examples of the substituent include a methyl group, an ethyl group, an isopropyl group, an alkyl group such as a [-butyl group, or a halogen-substituted alkyl group thereof, a methoxy group, an ethoxy group, a propoxy group, a butoxy group. Acyl groups such as alkoxy groups, formyl groups, acetyl groups, propionyl groups, butyryl groups,
Aralkyl groups such as benzyl group and 7enethyl group; aryloxy groups such as phenoxy group and tolyloxy group; alkoxycarbonyl groups such as methoxycarbonyl group, ethoxycarbonyl group, propoxycarbonyl group and butoxycarbonyl group; acetyloxy group and propionyl group. Oxy group, acyloxy group such as butyryloxy group, acylamino group such as acetylamino group, propionylamino group, butyrylamino group, aminocarbonyl group such as carbamoyl group, dimethylaminocarbonyl group, diethylaminocarbonyl group, phenoxycarbonyl group, tolyloxycarbonyl group , aryloxycarbonyl groups such as xylyloxycarbonyl groups, various halogen atoms, carboxyl groups, hydroxyl groups, and further substituents such as alkyl groups such as methyl, ethyl, and propyl groups, and alkoxy groups such as methoxy and ethoxy groups. A phenyl group with or without the formula % () (R1 and R2 in the formula are each a hydrogen atom, an alkyl group such as a methyl group, an ethyl group, a propyl group, a butyl group,
An acyl group such as a formyl group, an acetyl group, a propionyl group, a phenyl group or a substituted phenyl group such as a tolyl group or a xylyl group, which may be the same or different from each other, and may be different from each other. combine and replace,
It may form an unsubstituted saturated five-membered ring or a saturated six-membered ring, or it may form a substituted or unsubstituted saturated five-membered ring or a saturated six-membered ring by bonding with the group substituted on A r ' or A r 2. Examples include groups represented by (which may form a membered ring).

Ar' and Ar'' in formula (1) above may be the same or different, and may be bonded between the groups substituting them to form saturated or unsaturated However, at least one of the ring structures must be an aromatic residue having four or more unsaturated six-membered rings.

Among the distyryl pyrazine derivatives represented by the general formula (i), those in which the double bond site is in a trans structure are particularly preferred from the viewpoint of having strong fluorescence in the solid state; Among the substituents, alkyl groups and alkoxy groups are preferred for the same reason.

In the EL device of the present invention, specific examples of the distyrylpyrazine derivative represented by the above-mentioned formula (I) used as the luminescent material include the following compounds.

There are no particular restrictions on the manufacturing method of these compounds;
Conventionally known methods can be used.

For example, Ar'-CHolAr"-CHO (Ar' and A
r'' has the same meaning as above) and 2,5-dimethylpyrazine in the presence of an acid anhydride in a suitable solvent.

The light-emitting layer in the EL element of the present invention has the above-mentioned formula CI)
It can be formed by forming a thin film of the distyryl pyrazine derivative represented by, for example, a vapor deposition method, a spin code method, a casting method, an LB method, etc., but a molecular deposition film is particularly preferable. . Here, the molecular deposited film refers to a 14i film formed by depositing the distyrylpyrazine derivative from a gas phase state, or a film formed by solidifying the derivative from a solution state or a liquid phase state,
An example of this is a vapor-deposited film. Normally, this molecular deposition film is L
It can be distinguished from the thin film (molecular accumulation film) formed by method B. Moreover, the light-emitting layer is
As disclosed in Japanese Patent Application No. 6, etc., it is also possible to form a thin film by dissolving an adhesive such as a resin and the distyrylpyrazine derivative in a solvent to form a solution, and then forming the solution into a thin film using a spin coding method or the like. The thickness of the light-emitting layer thus formed is not particularly limited and can be selected depending on the situation, but is usually selected within the range of 5 nm to 5 μm.

The light-emitting layer in the EL element of the present invention has (1) an injection layer that can inject holes from the anode or the hole injection transport layer and can inject electrons from the cathode or the electron injection transport layer when an electric field is applied. (2) a transport function that moves injected charges (electrons and holes) using the force of an electric field; and (3) a light-emitting function that provides a field for recombination of electrons and holes, which leads to light emission. are doing. Furthermore, the ease with which holes are injected,
There may be a difference in the ease with which electrons are injected, and there may be a difference in the transport function represented by the mobility of holes and electrons, but it is preferable to move one of the charges.

The distyrylpyrazine derivative represented by formula (I) used in this light-emitting layer generally has an ionization energy smaller than about 6,000 V, so if an appropriate anode metal or anode compound is selected, it can be relatively positive. It is easy to inject holes, and since the voltage is larger than about 2.8 eV, if an appropriate cathode metal or cathode compound is selected, it is relatively easy to inject electrons, and it also has excellent electron and hole transport functions. Furthermore, since the fluorescence in the solid state is strong, it has a great ability to convert the excited state of the distyrylpyrazine derivative, its aggregates, or crystals formed upon recombination of electrons and holes into light.

There are various configurations of the EL element of the present invention, but basically, the light emitting layer is sandwiched between a pair of electrodes (an anode and a cathode), and if necessary, hole injection is performed. A transport layer or an electron injection transport layer may be provided. Specifically (1
) anode/emissive layer/cathode, (2) anode/hole injection transport layer/
Light emitting layer/cathode, (3) anode/hole injection transport layer/light emitting layer/
Configurations such as electron injection transport layer/cathode and (4) anode/light emitting layer/electron injection transport layer/cathode can be mentioned.

Although the hole injecting and transporting layer and the electron injecting and transporting layer are not necessarily required, the presence of these layers further improves the light emitting performance. Therefore, it is preferable to use at least an anode, a hole injection transport layer, a light emitting layer, and a cathode as constituent elements.

In addition, in the device having the above structure, it is preferable that each device is supported by a substrate, and the substrate is not particularly limited, and may be made of materials conventionally used in organic EL devices, such as glass, transparent plastic, quartz, etc. You can use the following.

As the anode in the organic EL device of the present invention, an electrode material containing a metal, an alloy, an electrically conductive compound, or a mixture thereof having a large work function (4 eV or more) is preferably used. A specific example of such an electrode material is Au.
%Cul, ITO1Sn02, ZnO, and other metals and conductive transparent materials. The anode can be manufactured by forming a thin film of these substances by a method such as vapor deposition or sputtering. When emitting light from this electrode, it is desirable that the transmittance be greater than 10%, and the sheet resistance of the electrode is preferably several hundred 0/port or less.

Furthermore, the film thickness depends on the material, but is usually 10 nm to 1 μ.
m1 is preferably selected in the range of 10 to 200 nm.

On the other hand, as a cathode, it has a small work function (4 eV or less).
Electrode materials made of metals, alloys, electrically conductive compounds, and mixtures thereof are used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium/copper mixture, AM/AIO□, indium, and the like. The cathode can be manufactured by forming a thin film of these substances by a method such as vapor deposition or sputtering. Further, the sheet resistance of the electrode is preferably several hundred 0/mouth or less, and the film thickness is usually selected in the range of 10 nm to 1pm, preferably 50 to 200 nm. In the device of the present invention, it is preferable that either the anode or the cathode be transparent or semi-transparent, since this allows light to be transmitted and extracted efficiently.

As described above, the structure of the EL device of the present invention has various aspects, and the hole injection transport layer in the EL device having the structure (2) or (3) above is a layer made of a hole transfer compound. It has the function of allowing holes injected from the anode to reach the light-emitting layer, and by interposing this hole injection transport layer between the anode and the light-emitting layer, many holes can emit light with a lower electric field. Electrons injected into the emissive layer from the cathode or the electron injection/transport layer are trapped near the interface in the emissive layer due to the electron barrier that exists at the interface between the emissive layer and the hole injection/transport layer. This results in an element with excellent light-emitting performance, such as increased luminous efficiency.

The hole transport compound used in the hole injection transport layer is arranged between two electrodes to which an electric field is applied, and when holes are injected from the anode, the hole transport compound is capable of appropriately transmitting the holes to the light emitting layer. Compounds that have a hole mobility of at least 10 cm'/V-5 when an electric field of 10' to lo' V/cI+ is applied are suitable.

There are no particular limitations on such hole transport compounds as long as they have the above-mentioned preferable properties. Any material can be selected from among the known materials used for the injection transport layer. Examples of the charge transport material include triazole derivatives (
(described in U.S. Pat. No. 3,112,197, etc.), oxadiazole derivatives (U.S. Pat. No. 3,189)
, 447, etc.), imidazole derivatives (described in Japanese Patent Publication No. 37-16096, etc.), polyarylalkane derivatives (U.S. Patent No. 3,61),
Specification No. 5,402, Specification No. 3,820,989,
Specification No. 3,542,544, Japanese Patent Publication No. 45-555, Japanese Patent Publication No. 51-10983, Japanese Patent Publication No. 51-932
Publication No. 24, Publication No. 55-17105, Publication No. 56-41
Publication No. 48, Publication No. 55-108667, Publication No. 55-1
56953, 56-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (
U.S. Pat. No. 3,180,729, 4,278
, 746 specification, JP-A-5588064, JP-A-5588064, 5
No. 5-88065, No. 49-105537,
No. 55-51086, No. 56-80051, No. 56-88141, No. 57-45545, No. 54-112637, No. 55-74546
(described in U.S. Pat. No. 3,615,404, Japanese Patent Publication No. 1983)
-10105 Publication, Publication No. 46-3712, Publication No. 47
-25336 publication, Japanese Patent Application Laid-open No. 54-53435,
No. 54-110536, No. 54-119925, etc.), arylamine derivatives (U.S. Pat.
Specification No. 03, Specification No. 3,240,597, Specification No. 3,
No. 658,520, No. 4,232,103, No. 4,175,961, No. 4,012,
Specification No. 376, Japanese Patent Publication No. 49-35702, No. 3
9-27577, JP 55-144250, JP 56-119132, JP 56-22437
No. 1,110,518, etc.), amino-substituted chalcone derivatives (described in U.S. Pat. No. 3,526,501, etc.), oxazole derivatives (U.S. Pat. 3,257,203 etc.), styryl anthracene derivatives (
Fluorenone derivatives (as described in JP-A-54-110837, etc.), hydrazone derivatives (as described in JP-A-54-110837, etc.),
717.462 specification, JP 54-59143, JP 55-52063, JP 55-52064, JP 55-46760, JP 55-85495
No. 57-11350, No. 57-1487
49), stilbene derivatives (JP-A-61-210363, JP-A-61-22)
No. 8451, No. 61-14642, No. 61-
No. 72255, No. 62-47646, No. 62
-36674 publication, 62-10652 publication, 62-10652 publication
2-30255, No. 60-93445, No. 60-94462, No. 60-174749, No. 60-175052, etc.).

In the present invention, these compounds can be used as hole transfer compounds, but the following porphyrin compounds (described in JP-A-63-295695 etc.), aromatic tertiary amine compounds and Styrylamine compounds (U.S. Pat.
No. 54-149634, No. 54-64299, No. 55-79450, No. 55-144250
No. 56-119132, No. 61-295
No. 558, No. 61-98353, No. 63-2
It is preferable to use the aromatic tertiary amine compound (described in Japanese Patent No. 95695, etc.), especially the aromatic tertiary amine compound.

Representative examples of the porphyrin compounds include porphine,
1,10,15.20-tetraphenyl-21H,23
H-porphine copper (II), 1.10,15.20-tetraphenyl-21H,23H-porphine zinc (11
), 5.10,15.20-tetrakis(pentafluorophenyl)-21H,23H-porphine.

Silicon phthalocyanine oxide, aluminum 7-lycyanine chloride, phthalocyanine (metal-free), dilithium phthalocyanine, copper tetramethyl phthalocyanine,
Examples include copper phthalocyanine, chromium 7-lysocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium 7-thalocyanine, and copper octamethyl phthalocyanine.

Representative examples of the aromatic tertiary amine compound and styrylamine compound include N,N,N',N'tetraphenyl-4,4'-diaminobiphenyl, N,N''-diphenyl-N,N' -di(3-methylphenyl) -4,
4″-diaminobiphenyl, 2,2-bis(4-di-p
-tolylaminophenyl)propane, 1,1-bis(4
-di-p-tolylaminophenyl)cyclohexane, N
, N,N',N'tetra-p-)dyl-4,4'-diaminobifynyl, 1,1-bis(4-di-pt-dylaminophenyl)-4-phenylcyclohexane, bis (4-dimethylamino-2-methylphenyl)phenylmethane, bis(4-p-)lylaminophenyl)phenylmethane, N,N'-diphenyl-N,N'-di(
4-methoxyphenyl)-4,4'diaminobiphenyl, N,N,N',N'-tetraphenyl-4,4'-diaminodiphenyl ether, 4,4'-bis(diphenylamino)quadryphenyl, N , N, N-tri (p
-tolyl)amine, 4-(di-p-tolylamino)-4
″-[4(di-p-tolylamino)styryl]stilbene, 4-N,N-diphenylamino-(2-diphenylvinyl)benzene, 3-methoxy-4′N,N-diphenylaminostilbene, N-phenylcarbazole Examples include.

The hole injection transport layer in the device of the present invention may be composed of a single layer composed of one or more of these hole transport compounds, or may be composed of a single layer composed of a compound different from the above hole transport compound. It may also be one in which injection transport layers are laminated.

On the other hand, the electron injection transport layer in the EL device having the configurations (3) and (4) above is made of an electron transfer compound and has the function of transmitting electrons injected from the cathode to the light emitting layer. . There are no particular limitations on such electron transfer compounds, and any one can be selected and used from conventionally known compounds. Preferred examples of the electron transfer compound include diphenylquinone derivatives such as [those described in "Polymer Preprints, Japan" Volume 37, No. 3, Page 681 (1988)], or nitro-substituted fluorenone derivatives, such as thiopyrane dioxide derivatives, etc. [[Japanese Journal of Applied Physics (J, J, Ap l.

Phys, ) J Vol. 27, L269 (1988)], anthraquinodimethane derivatives (JP-A-57-149259, JP-A-58-55450, JP-A-61-225151) , 61-233
No. 750, No. 63-104061, etc.), fluorenylidene methane derivatives (JP-A-60
-69657, 61-143764, 61-148159, etc.), anthrone derivatives (JP-A-61-225151, 61-148159, etc.);
-233750, etc.).

Furthermore, tBu-PBD is also valid.

Next, an example of a suitable method for manufacturing the organic EL device of the present invention will be explained for each device of each structure. To explain the method for manufacturing an EL device consisting of the above-described anode/emitting layer/cathode, first, a thin film of a desired electrode material, for example, an anode material, is deposited on a suitable substrate to a thickness of 1 μm or less, preferably in the range of 10 to 200 nm. After forming an anode by a method such as vapor deposition or sputtering to have a film thickness of A light emitting layer is provided. Methods for making the luminescent material into a thin film include, for example, a spin cord method, a casting method, an LB method, and a vapor deposition method. law is preferred. When this vapor deposition method is used to thin the luminescent material, the deposition conditions will vary depending on the type of organic compound used in the luminescent layer, the intended crystal structure and association structure of the molecular deposition film, etc. Generally boat heating temperature 50~400'C1 vacuum degree 10-'-10-''Pa, deposition rate 0.01-50
nm/sec, substrate temperature -50 to +30
It is desirable that the 0'C1 film thickness be appropriately selected within the range of 5 nm to 5 μm. Next, after forming this light emitting layer, a thin film made of a cathode material is deposited on it to a thickness of 1 μm or less, preferably 50 to 2 μm.
A desired organic EL element can be obtained by forming the film using a method such as vapor deposition or sputtering so as to have a film thickness in the range of 0.00 nm, and providing a cathode. Note that in manufacturing this EL element, it is also possible to reverse the manufacturing order and manufacture the cathode, the light emitting layer, and the anode in this order.

Next, E consisting of anode/hole injection/transport layer/emissive layer/cathode
To explain the manufacturing method of the L element, first, an anode is formed in the same manner as in the case of the EL element described above, and then a thin film made of a hole transport compound is formed by vapor deposition or the like on the anode, and hole injection and transport is performed. Provide layers. The vapor deposition conditions at this time may be based on the vapor deposition conditions for forming a thin film of the luminescent material. Next, on this hole injection transport layer, a light emitting layer and a cathode are sequentially placed.
A desired EL element can be obtained by providing it in the same manner as in the case of manufacturing the EL element. In the production of this EL element, it is also possible to reverse the production order and fabricate the cathode, light emitting layer, hole injection transport layer, and anode in this order.

Furthermore, to explain the method for manufacturing an EL device consisting of an anode/hole injection/transport layer/light emitting layer/electron injection/transport layer/cathode, first, the anode, hole injection After sequentially providing a transport layer and a light emitting layer, a thin film made of an electron transport compound is formed by vapor deposition on the light emitting layer to provide an electron injection transport layer, and then a cathode is placed on top of the EL element. A desired EL element can be obtained by providing it in the same manner as in the case of manufacturing. In the production of this EL element, the order of production may be reversed, and the cathode, electron injection and transport layer, light emitting layer, hole injection and transport layer, and anode may be produced in this order.

The organic EL device of the present invention thus obtained can output orange light and longer wavelength light with high brightness, for example, 1000 cd/m'' or more depending on the conditions.

When applying a DC voltage to the organic EL element of the present invention, the voltage is 5 to 40 V with the anode as + and the cathode as -.
When a certain degree is applied, light emission can be observed from the transparent or semi-transparent electrode side. Further, even if a voltage with the opposite polarity is applied, no current flows and no light is emitted. Further, when applying an alternating voltage, light is emitted only when the anode is in a positive state and the cathode is in a negative state. Note that the waveform of the applied alternating current may be arbitrary.

[Examples] Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples in any way.

Production Example 1 A 200m1 brown eggplant flask with branches was equipped with a condenser and a nitrogen gas inlet tube that reached the bottom of the flask.
-Pyrenecarboxaldehyde 10,009,2,5-
Dimethylpyrazine 1.57y, benzoic anhydride 9.839y
and Decalin 40taQ were added and heated under reflux for 10 hours.

After returning the reaction mixture to room temperature, add 100 ml of ethanol.
to form a precipitate, then filter the precipitate, and then add acetone 5 to remove unreacted aldehyde.
0ml! ! After stirring thoroughly in a vacuum chamber, the product was separated and dried under vacuum to obtain a reddish-purple crude product. t3g was obtained.

Next, this crude product was recrystallized three times with xylene to obtain 79 tags of reddish-purple needle crystals. The melting point of this thing is 31
The temperature was 0 to 312°C.

The reddish-purple needle-shaped crystals were confirmed to be 2,5-bis[2-(1-pyrenyl)vinyl]pyrazine by NMR and IR measurement using the KBr Beret method.

Example 1 A glass substrate (25x75x1.1+u+ size, manufactured by HOYA) on which an ITO transparent electrode with a film thickness of 100 nm is provided was used as a transparent support substrate, and this was ultrasonically cleaned with isopropyl alcohol for 30 minutes, and then washed with isopropyl alcohol. The transparent support substrate was immersed in alcohol, further blown dry with dry nitrogen gas, and the transparent support substrate was cleaned for 2 minutes using a U■ ozone cleaning device (manufactured by Samco International).
Finished cleaning. This was fixed to the substrate holder of a commercially available vacuum evaporation equipment, while the molybdenum resistance heating port was
N,N'-diphenyl-N,N'-di(3-methylphenyl)-4,4'-diaminobiphenyl (TPD) 2
00ffi9 was added, and 17011 g of the all-trans structure 2,5-bis[2-(1-pyrenyl)vinyl]pyrazine E compound of formula (2) obtained in Production Example 1 was added to another molybdenum resistance heating port. and attached it to the energizing terminal block of the vacuum evaporation equipment.

Next, after reducing the pressure in the vacuum chamber to IXIO-'Torr, electricity was applied to the port containing the TPD to reduce the deposition rate to 0.
．． 1-0.3 nm/see on a transparent support substrate,
A hole injection transport layer with a film thickness of 60 nm was provided. Furthermore, 2.
The port containing 5-bis[2-(1-pyrenyl)vinyl]pyrazine was energized at a deposition rate of 0.1-0.5 nm.
/see to provide a 30 nm thick light emitting layer on the hole injection transport layer. Note that the temperature of the substrate during vapor deposition was room temperature.

Next, the vacuum chamber was opened, and a stainless steel mask was placed on the light emitting layer, while a magnesium ribbon was placed in the molybdenum resistance heating port, and In was placed in the tungsten filament port. Attach these ports to the energizing terminal block and connect the vacuum chamber to the 8X10-
After reducing the pressure to 'Torr (inside the vacuum chamber), electricity is applied to the port to increase the deposition rate of Mg and In to 1 to 1.5 Torr, respectively.
4 nm/sec and 0.06 to 0.1 nm/s
Perform binary simultaneous vapor deposition so that Mg:I
An organic EL device was fabricated by forming an n (possibly a mixture of Mg and In) electrode.

When a slight DC voltage of 3.5 V was applied to this device using the ITO electrode as the positive electrode and the Mg:In electrode as the negative electrode, orange light emission that was visible under normal lighting was observed. When the applied voltage was further increased to 9.5V, 1 0 0 5 c
d/m'' high brightness orange light emission was obtained.The current value at this time was 326 mA/cm''. Further, when the spectrum was measured, there was a main luminescent component in the orange region (540 to 610 nm), but there was also a large luminescent component in the red region from 610 to 730 nm. (The integrated emission intensity ratio is the former:
The latter #3:2. ) The above example is one example showing that high brightness orange light and longer wavelength light emission is possible.

By comparing with Japanese Patent Application No. 175936 previously filed by the present inventors, it was found that the general formula (I)
It can be inferred that the object of the present invention, for example, high-intensity red light emission, can be easily achieved by providing various large aromatic ring groups at the positions of Ar' and Ar'' in the substrate cleaning conditions and vapor deposition conditions. It seems possible to obtain even better data than in Example 1 by improving the process or changing the element configuration.

[Effects of the Invention] The organic EL device of the present invention can output orange light and longer wavelength light at a high luminance of 1000 cd/m or more depending on the conditions, can be multicolored, and can be visually recognized. It has excellent properties and is suitably used as various display elements.

Claims (1)

[Claims] 1 Luminescent materials include general formulas ▲ mathematical formulas, chemical formulas, tables, etc. A monovalent group consisting of an aromatic ring, the remainder of which is an aromatic ring having three or more unsaturated six-membered rings, which may be the same or different from each other. An organic electroluminescent device characterized by using a distyrylpyrazine derivative represented by 2. The organic electroluminescent device according to claim 1, comprising a thin film-like light-emitting layer made of a distyrylpyrazine derivative represented by the general formula (I). 3. The organic electroluminescent device according to claim 2, comprising at least an anode, a hole injection transport layer, a light emitting layer, and a cathode.