JPH02252793A - Organic electroluminescent element - Google Patents

Abstract

PURPOSE:To obtain the title element capable of emitting a yellow light with high luminance at a low voltage by putting a thin-film luminescent layer comprising a distyrylpyrazine derivative between a pair of electrodes. CONSTITUTION:A thin film of an anode substance having a thickness of 1mum or less, preferably 10-200nm, is formed on a substrate to give an anode, on which a thin film of a luminescent material comprising a distyrylpyrazine derivative of the formula (wherein X and Y are each a monovalent aromatic residue or heteroaromatic residue) and having a thickness of 5nm to 5mum is formed under the conditions of a boat heating temperature of 50-400 deg.C, a degree of vacuum of 10<-5>-10<-3>Pa, a rate of deposition of 0.01-50nm/sec, and a substrate temperature of -50 to 300 deg.C to provide a luminescent layer. A thin film of a cathode substance having a thickness of 1mum or less, preferably 50-200nm, is then formed to provide a cathode on the luminescent layer, thus giving the title element having a luminescent layer comprising a distyrylpyrazine derivative put between a pair of electrodes.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a novel organic electroluminescent device. More specifically, the present invention relates to an organic electroluminescent device that is suitable as a light emitting device for various display devices and is capable of outputting yellow and green light with particularly low voltage and high brightness.

[Conventional technology]

In recent years, electroluminescent elements (hereinafter referred to 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 device 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. are doing. 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. [
"Agelide Physics Letters" Volume 51, Page 913 (1987)]. Various types of organic EL devices have been developed so far, such as (1) a stacked type device consisting of an anode/hole injection zone/emission zone/cathode structure (Japanese Patent Laid-Open No. 59-194393;
(2) Anode/hole injection transport band/emission band/
A laminated type that has the structure of a cathode and whose emission band consists of a host material that has the function of injecting electrons and holes, doped with a fluorescent material that emits light in response to the recombination of holes and electrons. (3) using 12-7-roperinone as a luminescent material; device [Japanese Journal of Applied Physics Letters (J, J, Ap
pl, Phys, Lett,) J Volume 27, L713
(1988)] have been disclosed. In the device (1) above, high-intensity blue-green, blue, and orange light emission of several hundred e d/m' can be obtained at a low voltage of about 20"V. For example, when the hole injection band is By using a phenylamine derivative and an aluminum oxine complex in the emission band, green light emission of 340 cd/m'' was achieved.
In addition, by using a benzoxazole-based fluorescent whitening agent in the emission band, high-intensity blue-green and orange light emission is achieved. - On the other hand, in the element (2), low voltage, high brightness red,
Green and blue-green light emission has been obtained, but in the case of element (-3), an applied voltage of about 50 V can only produce light emission with an output of about 1 mW/cta' that can be seen in yellow bright light. do not have. As described above, the reality is that high-output yellow light emission has not yet been achieved in conventional organic EL devices. [Problems to be Solved by the Invention] Under these circumstances, the present invention was made with the purpose of providing a novel organic EL element that can output yellow light with high brightness at low voltage. It is something that [Means for Solving the Problems J] As a result of extensive research in order to achieve the above object, the present inventors have discovered that an organic EL device using a distyrylpyrazine derivative as a luminescent material has a high luminance yellow color and It was discovered that green light emission can be output at low voltage, and the present invention was completed based on this knowledge. That is, the present invention uses a distyrylpyrazine derivative as a luminescent material, particularly a distyrylpyrazine derivative with the general formula %() (in which X and Y are each a -valent aromatic residue or a heteroaromatic residue, and may be the same or different). The present invention will be explained in detail below. In the EL device of the present invention, the distyrylpyrazine derivative used as the luminescent material is particularly preferably a compound having a distyrylpyrazine skeleton structure represented by the general formula (R), which exhibits fluorescence in the solid state, In addition to providing mobility of electrons and holes, due to the conjugated nature of the distyrylpyrazine skeleton, it has low ionization energy and high electron affinity, so it has characteristics such as easy charge injection from electrodes etc. X and Y in the general formula (1) are each a -valent aromatic residue or a heteroaromatic residue, and examples of the aromatic residue include a phenyl group, a naphthyl group, and an anthyl group. , styryl group, etc.; examples of heteroaromatic residues include furyl group, thienyl group, pyrrolyl group, pyridyl group, quinolyl group, thiazolyl group, oxasilyl group, imidazolyl group, benzoxasilyl group, benzothiazolyl group , a benzimidazolyl group, a carbazolyl group, a triazole group, a monovalent group consisting of a pyrazoline group, etc. These aromatic residues and heteroaromatic residues may contain various types of residues as long as the above characteristics are not impaired. A substituent may be introduced. Examples of the substituent include an alkyl group such as a methyl group, an ethyl group, an isopropyl group, a 1-butyl group, or a halogen-substituted alkyl group thereof, a methoxy group, an ethoxy group, a propoxy group, Alkoxy groups such as butoxy groups, acyl groups such as formyl groups, acetyl groups, propionyl groups, butyryl groups, aralkyl groups such as benzyl groups and phenethyl groups, aryloxy groups such as phenoxy groups and tolyloxy groups, methoxycarbonyl groups, and ethoxy groups. Alkoxycarbonyl groups such as carbonyl, propoxycarbonyl and butoxycarbonyl groups; acyloxy groups such as acetyloxy, propionyloxy and butyryloxy groups; acylamino groups such as acetylamino, globionylamino and butyrylamino groups; carbamoyl groups ,
Aminocarbonyl groups such as dimethylaminocarbonyl group and carbonyl group, aryloxycarbonyl groups such as phenoxycarbonyl group, tolyloxycarbonyl group and xylyloxycarbonyl group, various halogen atoms, carboxyl group, hydroxyl group, as well as methyl group and ethyl group. , an alkyl group such as a propyl group, a phenyl group with or without a substituent such as an alkoxy group such as a methoxy group or an ethoxy group, and a general formula (R1 and Rz in the formula are a hydrogen atom, a methyl group, an ethyl group, respectively) group, alkyl groups such as propyl group, 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 l;
They may be different from each other, or may be bonded to each other to form a substituted or unsubstituted saturated five-membered ring or saturated six-membered ring, or may be bonded to a group substituted in X%Y. (which may form a substituted or unsubstituted saturated five-membered ring or a saturated six-membered ring) and the like. X and Y in the general formula (I) may be the same or different, and the groups substituting them may be bonded to form a saturated or unsaturated ring structure. It may be formed. Among the distyrylpyrazine derivatives represented by the general formula (I), those in which the double bond has a trans structure are particularly preferred from the viewpoint of having strong fluorescence in the solid state.
Furthermore, among the above 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 general formula (I) used as the luminescent material include the following compounds. (l 6) CH,0 0(M3 (l 4) CH. Among these compounds, 2.5-bis-(2-
(4-hyphenyl)ethynyl]viracinha is a new compound not described in the literature, which is produced by, for example, reacting p-phenylbenzaldehyde and 2,5-dimethylpyrazine in the presence of an acid anhydride. be able to. Ma I
;, Compounds other than (4) are, for example, [Journal of Polymer Science Polymer Physics Edition (J, Polymer Sci, Polymer
erPhys, Ed.) J, Vol. 16, p. 1365 (1968). The light-emitting layer in the EL element of the present invention has the above general formula (1).
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 term "molecularly deposited film" refers to a thin film formed by depositing the distyrylpyrazine derivative from the gas phase, or a film formed by solidifying the distyrylpyrazine derivative from the solution state or liquid phase, for example, by vapor deposition. This is the membrane. Usually, this molecular deposit film can be distinguished from a thin film (molecular cumulative film) formed by the LB method. Furthermore, as disclosed in Japanese Patent Publication No. 64-7636, etc., the light-emitting layer is prepared by dissolving an adhesive such as a resin and the distyrylpyrazine derivative in a solvent to form a solution, and then using a spin code method to form a solution. The film is made thinner by such methods as
It can also be formed. 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) injection function; transport function that moves charges (electrons and holes) by the force of an electric field; (3) light emitting function that provides a field for recombination of electrons and holes, which leads to light emission, etc. have. Note that there may be a difference in the ease with which holes are injected and the ease with which electrons are injected, and there may be differences in the transport function expressed by the mobility of holes and electrons, but one or the other may be different. It is preferable to move the charge of . The distyrylpyrazine derivative represented by the general formula (I) used in this light emitting layer generally has an ionization energy of
6. Since it is smaller than about OeV, it is relatively easy to inject holes if a suitable anode metal or anode compound is selected. Also, since it is larger than about 2.8 eV, if a suitable cathode metal or cathode compound is selected, it is relatively easy to inject holes. In addition to being easy to inject, 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/
Examples include structures such as an electron injection transport layer/cathode. 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. In the device having the above structure, it is preferable that each device is supported by a substrate, and there is no particular restriction on the substrate, and materials conventionally used in organic EL devices, such as glass, transparent plastic, and quartz, can be used. It is possible to use one consisting of 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.
1 Cul, ITO. Examples include metals and conductive transparent materials such as SnO, ZnO. 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 07 or less. Although the rough film thickness depends on the material, it is usually selected in the range of IQ nm to 1 μm, preferably 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 using metals, alloys, electrically conductive compounds, and mixtures thereof are also used. Specific examples of such electrode materials include sodium, sodium-potassium alloy, magnesium, lithium, magnesium/copper mixture, AI/A101, indium, and the like. The cathode can be manufactured by forming *i with these substances by a method such as vapor deposition or sputtering. Further, the sheet resistance of the electrode is preferably several hundreds of nanometers or less, and the film thickness is usually selected in the range of 10 nm to lpm, 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 transmitting holes injected from the anode to 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 applied with an electric field; when placed between two electrodes and holes are injected from the anode, the hole transport compound is capable of appropriately transmitting the holes to the light emitting layer. For example, a compound having a hole mobility of at least 10-'Cm''/V-5 when an electric field of 10' to lo''V3Ga is applied is 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 (
No. 3,112,197), oxadiazole derivatives (U.S. Pat. No. 3,189, etc.),
, 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,
3.542,544 specification, Japanese Patent Publication No. 45-555, Japanese Patent Publication No. 51-10983, Japanese Unexamined 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, ri156-36656, etc.), pyrazoline derivatives and pyrazolone derivatives (U.S. Patent No. 3,180,729, 4,2
78,746 specification, JP-A-55-8.8064, JP-A-55-88065, JP-A-49-105537
No. 55-51086, No. 56-8005
Publication No. 1, Publication No. 56-88141, Publication No. 57-455
Publication No. 45, Publication No. 54-112637, Publication No. 55-7
4546), phenylenediamine derivatives (U.S. Pat. Showa 54-53435
No. 54-110536, No. 54-119
No. 925, etc.), arylamine derivatives (U.S. Patent No. 3,567,450, No. 3,1
No. 80,703, No. 3,240,597, No. 3.658,520, No. 4,232,10
Specification No. 3, Specification No. 4,175,981, No. 4,0
Specification No. 12,376, Japanese Patent Publication No. 49-35702, Japanese Patent Publication No. 39-27577, Japanese Patent Application Publication No. 14425-1987
Publication No. 0, Publication No. 56-119132, Publication No. 56-22
No. 437, West German Patent No. 1,110,518, etc.), amino-substituted chalcone derivatives (US Pat. No. 3,526,501, etc.)
, oxazole derivatives (U.S. Pat. No. 3,257,203)
Styryl anthracene derivatives (described in JP-A-56-46234, etc.), fluorenone derivatives (described in JP-A-54-110837, etc.), hydrazone derivatives (described in JP-A-54-110837, etc.) U.S. Patent No. 3,717,462, JP 54-5914
Publication No. 3, Publication No. 55-52063, Publication No. 55-520
Publication No. 64, Publication No. 55-46760, Publication No. 55-85
Publication No. 495, Publication No. 57-11350, Publication No. 57-1
48749, etc.), stilbene derivatives (JP-A-61-210363, JP-A-61-210363, etc.)
-228451 publication, 61-14642 publication, 61-72255 publication, 62-47646 publication,
62-36674, 62-10652, 62-30255, 60-93445, 60-94462, 60-174749
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 (US Pat. No. 4,127,412, JP-A-53-27033, JP-A-54-58445,
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,23H-porphine steel (n), 1.10.
Is, 20-tetraphenyl-21H,23H-porphine zinc 1), 5.10,15.20-tetrakis(pentafluorophenyl)-2LH,23H-porphine, silicon 7-thalocyanine oxide, aluminum 7-lycyanine chloride, Examples include phthalocyanine (metal-free), dilithium 7-thalocyanine, copper tetramethyl phthalocyanine, copper 7-thalocyanine, chromium phthalocyanine, zinc phthalocyanine, lead phthalocyanine, titanium phthalocyanine oxide, magnesium phthalocyanine, copper octamethyl phthalocyanine, and the like. Representative examples of the aromatic tertiary amine compounds and styrylamine compounds 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-)lylaminophenyl)propane, I, 1-bis(4-di-p- -tolylaminophenyl)cyclohexane, N, N, N″N
l-tetra-p-tolyl-4,4'-diaminobiphenyl, 1,1-bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane, bis(4-dimethylamino-2-methylphenyl)phenylmethane , bis(4-p-tolylaminophenyl)phenylmethane, N,N''-diphenyl-N,N'-di(4-methoxyphenyl)-4,4'diaminobiphenyl, N,N,N
',N'-tetra722-4,4'-diaminodiphenyl ether, 4,4'-bis(diphenylamino)quadrifhenyl, ・N,N,N-tri(p-tolyl)
Amine, 4-(j-p-)lylamino)-4'-(4(
di-p-tolylamino)styryl]stilbene, 4-N
, N-diphenylamino-(2-diphenylvinyl)benzene, 3-methoxy-4''-N, N-diphenylaminostilbene, N-phenylcarbazole, etc. The hole injection transport layer in the device of the present invention includes: It may be composed of a single layer consisting of one of these hole-transporting compounds or 2fl11 or more, or it may be a stack of hole-injecting and transporting layers made of a compound different from the above-mentioned layer. On the other hand, the electron injection transport layer in the EL element having the configuration (3) above is made of an electron transfer compound and has the function of transferring electrons injected from the cathode to the light emitting layer. There are no particular restrictions on the electron transfer compound;
Any compound can be selected and used from conventionally known compounds. Preferred examples of the electron transfer compound include diphenylquinone derivatives such as [Polymer Preprint (Pol
ymer Preprints), Japan” No. 37
Vol., Wc No. 3, p. 681 (19B8), etc. 1, or nitro-substituted fluorenone derivatives, thiopyrane dioxide derivatives, etc. [Japanese Journal of Applied Physics ( J, J, Apply. Phys, ) J Vol. 27, L269 (1988)], anthraquinodimethane derivatives (JP-A-57-149259, JP-A No. 5B-55450, JP-A No. 57-55450, Publication No. 61-225151, No. 61-2337
No. 50, No. 63-104061, etc.), 7 leolenylidene methane derivatives (Japanese Patent Application Laid-open No. 1983-
No. 69657, No. 61-143764, No. 6
1-148159, etc.), anthrone derivatives (JP-A-61-225151, JP-A-61-1986)
Examples include those described in Japanese Patent No. 233750, etc.). 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, the spin foot method, the casting method, the LB method, and the vapor deposition method, but the vapor deposition method is preferred because it is easy to obtain a homogeneous film and is less likely to generate pinholes. is preferred. When this vapor deposition method is used to thin the luminescent material, the deposition conditions vary depending on the type of organic compound used in the luminescent layer, the desired crystal structure and association structure of the molecular deposited film, but generally Port heating temperature 50-400℃, vacuum degree 1O
-=10-"Pa, deposition rate o, oi~50nm/se
c, substrate temperature -50 to +300°C, film thickness 5 nm to 5
It is desirable to select it appropriately within the range of μm. Next, after forming this light-emitting layer, a thin film of cathode material is deposited on it to a thickness of 1 μm.
Thereafter, a desired organic EL element can be obtained by forming the film by a method such as vapor deposition or sputtering so as to preferably have a film thickness in the range of 50 to 200 nm, and providing a cathode. In addition, in the production of 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, the anode is formed in the same manner as in the case of the EL element described above. An injection transport layer is provided. The deposition conditions at this time are:
The vapor deposition conditions for forming a thin film of the luminescent material may be the same as described above. Next, a light-emitting layer and a cathode are sequentially provided on this hole injection transport layer in the same manner as in the production of the EL device, thereby obtaining a desired EL device. 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. When applying a DC voltage to the organic EL device of the present invention obtained in this way, when a voltage of about 5 to 40 V is applied with the anode as the opposite polarity and the cathode as the negative polarity, the light emission becomes transparent or translucent. It can be observed from the electrode side. Further, even if a voltage with the opposite polarity is applied, no current flows and no light is emitted. Furthermore, when applying AC voltage, the anode is + and the cathode is -.
Lights up only when the condition is reached. Note that the waveform of the applied alternating current may be arbitrary. [Example] 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 2,5-bis-(2-4-biphenylacetate) L p-phenylbenzaldehyde 7.189. 2.5-dimethylpyrazine 1.0099 and benzoic acid 9.959 were mixed and refluxed for 21 hours. After that, f7) the reaction mixture was poured into 100ml of ethyl alcohol to form a precipitate. Next, this precipitate was filtered, washed with ethyl alcohol, and then dried in vacuum to obtain 0.489 of a crude product. Next, this crude product was purified by sublimation to obtain a yellow powder, and then recrystallized with 400 tal of xylene (activated carbon treatment) to obtain 300 s+g of yellow needle-shaped crystals. The melting point of this product was 310-313°C (decomposed). Other distyrylpyrazine derivatives are described in "Journal of Polymer Science, Polymer Physics, and Edication (J, PolymerScf, Pol.
ymer phys, Ed, ) J Volume 16, No. 136
It was produced by the method described on page 5 (1968). Example 1 A glass substrate (25 x 75 x 1.1 mm size, manufactured by HOYA) on which an ITO transparent electrode with a film thickness of 1100 nm was provided was used as a transparent support substrate, and this was ultrasonically cleaned with isopropyl alcohol for 30 minutes, and then further washed with isopropyl alcohol. Soaked and washed. This transparent support substrate was dried with dry nitrogen gas, fixed on a substrate holder of a commercially available vacuum evaporation device, and then placed on a molybdenum resistance heating boat with N,N'
diphenyl-N,N'-bis(3-methyl7enyl)-
(1,1″-biphenyl)-4,4″-diamine (TP
D) 200 rag of 2゜5-bis-(2-(4-biphenyl)ethynyl) with all-trans structure obtained in Production Example 1 was placed in another molybdenum resistance heating boat.
Add 200IIIg of pyrazine [compound of formula (4)],
It was attached to a vacuum evaporation device. Next, after reducing the pressure in the vacuum chamber to 1.2xlO-'Pa, the heating boat containing the TPD was energized to 230
℃ and deposited on a transparent support substrate at a deposition rate of 0.1 to 0.3 nm/see to provide a hole injection transport layer with a thickness of 60 nm. Further, the boat containing 2,5-bis-(2-(4-biphenyl)ethynyl)pyrazine was heated to 285°C by applying electricity, and the vapor deposition rate was 0.1 to 01 nm/
sec to deposit the hole injection transport layer to a film thickness of 7.
A light emitting layer of 0 nm was provided. 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 top of the luminescent layer, while 3 g of magnesium was placed in a resistance heating boat made of molybdenum and copper was placed in a crucible of an electron beam evaporator, and the vacuum chamber was opened again. After reducing the pressure to 2×1O-Pa, the boat containing magnesium was energized to increase the deposition rate to 4.
Magnesium is evaporated at ~5 nm/Sec, and at the same time copper is heated by an electron beam to achieve a deposition rate of 0.1~
The intended EL element was fabricated by vapor depositing copper at a rate of 0.3 nm/see to form a counter electrode made of the mixture of magnesium and copper. When a direct current of 17"/cm was applied using the ITO electrode of this device as the positive electrode and the counter electrode made of a mixture of Mg and copper as the negative electrode, a current with a current density of 300mA/crm" flowed.
A yellow luminescence was obtained. The maximum emission wavelength at this time is 548 nm
1 emission brightness is 100 cd/m! Example 2 A glass substrate (25 x 75 x 1.1 mm size, manufactured by HOYA) on which an ITO transparent electrode with a film thickness of 1100 nm was provided was used as a transparent support substrate, and this was ultrasonically cleaned with inpropyl alcohol for 30 minutes. Furthermore, it was washed by immersing it in isopropyl alcohol. This transparent support substrate was dried with dry nitrogen gas and fixed to the substrate boulder of a commercially available vacuum evaporation apparatus, while the TPD2 was placed in a molybdenum resistance heating boat.
00*y, and in another molybdenum resistance heating boat, 2,5-bis-(4-ethylstyryl)pyrazine with an all-trans structure [1200 mg of compound of formula (2)]
and attached it to a vacuum evaporator. Next, after reducing the pressure in the vacuum chamber to 3 x 10-'Pa, electricity was applied to the heating boat containing TPD to heat it to 230°C, and vapor deposition was performed on the transparent support substrate at a vapor deposition rate of 0.1 to 0.3 nm/sac. Then, a hole injection transport layer with a film thickness of 70 nm was provided. Furthermore, the boat containing 2,5-bis-(4-ethylstyryl)pyrazine is heated to 200°C by applying electricity,
A light emitting layer having a thickness of 80 nm was provided by vapor deposition on the hole injection transport layer at a vapor deposition rate of 0.1 to 0.3 nm/sec. 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 top of the luminescent layer, while 3 g of magnesium was placed in a resistance heating boat made of molybdenum and copper was placed in a crucible of an electron beam evaporator, and the vacuum chamber was opened again. After reducing the pressure to 2xiO-'Pa, the boat containing magnesium was energized to deposit magnesium at a deposition rate of 5 to 6 nm/SμC.
At the same time, the copper is heated by an electron beam and the deposition rate is 0.2.
The desired EL element was fabricated by vapor depositing copper at a rate of ~0.3 nm/see to form a counter electrode made of the mixture of magnesium and copper. When a DC voltage of 13 V was applied using the ITO electrode of this device as the positive electrode and the counter electrode made of a mixture of Mg and steel as the negative electrode, a current with a current density of 33 mA/cm" flowed.
A green luminescence was obtained. The maximum emission wavelength at this time is 512 nm
x Emission luminance was 270 cd/m''; Q Example 3 A glass substrate (25 x 75 x 1.1 + 1 m size, manufactured by HOYA) on which an ITO transparent electrode with a film thickness of 1100 nm was provided was used as a transparent support substrate, and this was coated with isopropyl alcohol. The transparent support substrate was cleaned using ultrasonic waves for 30 minutes, and then immersed in isopropyl alcohol.The transparent supporting substrate was dried with dry nitrogen gas and fixed to a substrate holder of a commercially available vacuum evaporation device. TP to heating boat
2.5-bis-(4-
200 mg of methoxystyryl) pyrazine (compound (18) (7)) was placed in a vacuum evaporation apparatus.Next, after reducing the pressure in the vacuum chamber to 2X10-'Pa, T
Turn on the PD; energize the heating boat to 220'O
The film was heated to 100 nm, and vapor-deposited on a transparent support substrate at a vapor deposition rate of 0.1 to 0.3 nm/sec to provide a hole injection transport layer with a film thickness of 60 nm. Further, the port containing 2,5-bis-(4-methoxystyryl)pyrazine was energized at 230°C.
heating to a deposition rate of 0.1-0.3 nm/s
e c, the film is deposited on the hole injection transport layer to a film thickness of 9.
A light emitting layer of 0 nm was provided. 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 top of the luminescent layer, while 3 g of magnesium was placed in a resistance heating boat made of molybdenum and copper was placed in a crucible of an electron beam evaporator, and the vacuum chamber was opened again. After reducing the pressure to 2X10-'Pa, the boat containing magnesium is energized to deposit magnesium at a deposition rate of 6 nm/sec. At the same time, copper is heated by an electron beam to achieve a deposition rate of 0.1 to 0.
．． The intended EL element was manufactured by vapor depositing copper at a rate of 3 nm/see to form a counter electrode made of the mixture of magnesium and copper. When a direct current of 17 V was applied using the ITO electrode of this device as the positive electrode and the counter electrode made of a mixture of Mg and copper as the negative electrode, a current with a current density of 190 mA/cm" flowed and blue-green light was emitted. The maximum emission wavelength at this time is 497 nm
The luminance was 160 cd/m8. Example 4 A glass substrate (25 x 75 x 1.1 m + m size, manufactured by HOYA) on which an ITO transparent electrode with a film thickness of 1100 nm was provided was used as a transparent support substrate, and this was ultrasonically cleaned with isopropyl alcohol for 30 minutes, and further washed with inpropyl alcohol. It was soaked in and washed. This transparent support substrate was dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation device, and placed in a resistance heating boat made of molybdenum.
4-bis-(4-methylstyryl)pyrazine [formula (1)
1200 mg of the compound was added thereto, and the mixture was attached to a vacuum evaporation apparatus. Next, the pressure in the vacuum chamber was reduced to 2xlO-'Pa, and 1.
The port containing 4-bis-(4-methylstyryl)pyrazine was heated to 210°C by applying electricity, and the deposition rate was 0.
A light emitting layer having a thickness of 500 nm was provided by vapor deposition on a transparent support substrate at a rate of 1 to 0.3 nm/sec. 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 top of the luminescent layer, while 3 g of magnesium was placed in a resistance heating boat made of molybdenum and copper was placed in a crucible of an electron beam evaporator, and the vacuum chamber was opened again. After reducing the pressure to 2×10-'Pa, the port containing magnesium was energized to deposit magnesium at a deposition rate of 4 to 5 nm/see.
At the same time, the copper is heated by an electron beam and the deposition rate is 0.2.
Copper was deposited at a rate of ~0.3 nm/sec to form a counter electrode made of a mixture of magnesium and copper, thereby producing the desired EL element. When 30 V DC was applied to this device using the ITO electrode as the positive electrode and the counter electrode made of a mixture of Mg and copper as the negative electrode, a current with a current density of 30 mA/cm" flowed and green light was emitted. The maximum emission wavelength was 520 nm, and the emission brightness was 0.5 cd/m''. Example 5 Glass substrate (25x75x1.1ms+size, H
(manufactured by OYA Corporation) was used as a transparent support substrate, which was ultrasonically cleaned with isopropyl alcohol for 30 minutes, and further immersed in isopropyl alcohol for cleaning. This transparent support substrate was dried with dry nitrogen gas, fixed to a substrate holder of a commercially available vacuum evaporation device, and TPD was placed on a resistance heating boat made of molybdenum.
200jlIg of 2,5-bis(
2-(1-naphthyl)vinyl)pyrazine (Specific Example 21 of Luminescent Material) was charged for 200 my and attached to a vacuum evaporation apparatus. After this, the pressure in the vacuum chamber was reduced to 4X10-'Pa, and T
The boat containing the PD was energized, heated to 230"O, and deposited on a transparent support substrate at a deposition rate of 0.1 to 0.3 nm/see. Furthermore, 2.5-bis(2-(1-su2
energizing the boat containing vinyl) pyrazine;
Heated to 242℃, deposition rate 0.3nm/s e
The film was deposited on the hole injection layer on the transparent support substrate in step c, and the film thickness was 6.
A light emitting layer of 0 nm was obtained. The temperature of the substrate during deposition was room temperature. After this, the vacuum chamber was opened, a stainless steel mask was placed on top of the luminescent layer, 3g of magnesium was placed in a molybdenum resistance heating boat, steel was placed in the crucible of the electron beam evaporator, and the vacuum chamber was opened again. The pressure was reduced to 2xlO-'Pa, and then the boat containing magnesium was energized to deposit magnesium at a deposition rate of 4 to 6 nm/sec. At this time, the copper is simultaneously heated by an electron beam to 0.
Copper was deposited at a rate of 1-0.3 nm/sac, and copper was mixed with the magnesium to form a counter electrode. With the above steps, the production of the electroluminescent device was completed. The ITO electrode of this device was used as the positive electrode, the counter electrode made of a mixture of Mg and copper was used as the negative electrode, and when 12 V DC was applied,
A current with a current density of 213 mA/cm" was passed, and yellow light was emitted. The maximum wavelength of light emission at this time was 565 nm, according to CIE
The chromaticity coordinates are x=0.40, y-0,53 (Yet lo
wQreen), and the luminance was 932 cd/m'', which was extremely high luminance. [Effects of the Invention] The organic EL device of the present invention uses a distyryl pyrazine derivative as a luminescent material, and has yellow and green luminance. It can emit light with high brightness, especially at low voltage, and is suitably used as a light emitting element in various display devices.

Claims (1)

[Scope of Claims] 1. An organic electroluminescent device characterized in that a distyrylpyrazine derivative is used as a luminescent material. 2 Distyrylpyrazine derivatives have a general formula ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ... (I) (X and Y in the formula are each a monovalent aromatic residue or a heteroaromatic residue, and they are The organic electroluminescent device according to claim 1, which is a compound represented by the following formula (which may be the same or different). 3. The organic electroluminescent device according to claim 1 or 2, comprising a thin film-like light-emitting layer made of a distyrylpyrazine derivative represented by general formula (I). 4. The organic electroluminescent device according to claim 3, comprising a light-emitting layer interposed between a pair of electrodes. 5. The organic electroluminescent device according to claim 4, comprising an anode, a hole injection transport layer, a light emitting layer, and a cathode stacked in this order.