JPH10294179A - Organic electroluminescence element and luminescence material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence element which can be driven with high light emitting efficiency in a short wave length area, particularly, a blue area by containing an anthracene derivative in an organic light emitting layer by sandwiching a hole transport layer and the organic light emitting layer by an anode and a cathode on a base board. SOLUTION: A luminescence material used for an organic light emitting layer is composed of an anthracene derivative expressed by a formula. In the formula, R<1> and R<6> represent -H, -OH, -CH3 , -OCH3 or the like, and Ar<1> to Ar<4> represent phenyl, p-tolyl or the like. R<1> to R<6> and Ar<1> to Ar<6> may be the same with each other, or may be different from each other. This anthracene derivative is doped on the organic light emitting layer, and light emitting efficiency of an organic electroluminescence element can be enhanced. Since this anthracene derivative is effective even in structurally stabilizing a thin film condition of the organic light emitting layer, long-term stability of the organic electroluminescence element can be improved.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescent device and a fluorescent material. More specifically, the present invention relates to a combination of a hole transport layer made of an organic compound and an organic light emitting layer, which emits light by applying an electric field. The present invention relates to a thin film device and a fluorescent material useful as a light emitting material of such an organic electroluminescent device.

[0002]

2. Description of the Related Art Conventionally, as a thin film type electroluminescent (EL) element, Zn, which is a group II-VI compound semiconductor of an inorganic material, is used.
In general, S, CaS, SrS, and the like are doped with Mn or a rare earth element (Eu, Ce, Tb, Sm, or the like) which is a luminescence center. However, EL devices manufactured from the above inorganic materials include: 1) AC drive is required (typically 50-1000 Hz). 2) High driving voltage (generally about 200 V). 3) It is difficult to achieve full color, and there is a problem particularly with blue. 4) The cost of the peripheral drive circuit is high. There is a problem that.

However, in recent years, in order to improve the above problems,
Development of EL devices using organic thin films has been started. In particular, in order to enhance the luminous efficiency, the type of the electrode was optimized for the purpose of improving the efficiency of carrier injection from the electrode, and a hole transport layer composed of an aromatic diamine and a luminescent layer composed of an aluminum complex of 8-hydroxyquinoline were used. Of an organic electroluminescent device provided with an electrode (Appl. Phys. Lett., 51
Vol., P. 913, 1987), the luminous efficiency is greatly improved as compared with the conventional EL device using a single crystal such as anthracene, and the practical characteristics are approached.

[0004] In addition to the electroluminescent device using a low molecular material as described above, poly (p-phenylenevinylene) (Nature, 347, 539, 1990, etc.)
Poly [2-methoxy-5- (2-ethylhexyloxy) -1,4
-Phenylene vinylene] (Appl. Phys. Lett., Vol. 58,
1982, 1991 etc.), poly (3-alkylthiophene)
(Jpn. J. Appl. Phys, Vol. 30, L1938, 1991, etc.) and the development of electroluminescent devices using polymer materials, as well as low molecular light emitting materials and electron transfer materials for polymers such as polyvinyl carbazole (Applied Physics, 61, 1044, 1992)
Year) is also being developed.

For example, doping a fluorescent dye for laser such as coumarin using an aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Phys., 65)
Vol. 3610, 1989).

[0006]

However, in the organic electroluminescent devices disclosed so far, the luminous efficiency in the visible short wavelength region, particularly in the blue region, is still insufficient, and further improvement studies are desired. It is the present situation.

The fact that the deterioration due to dark spots of the organic electroluminescent element is not improved and the light emission characteristics are unstable is a serious problem for a light source such as a facsimile, a copying machine, and a backlight of a liquid crystal display. Is not desirable.

The present invention has been made in view of the above-mentioned conventional situation, and has as its object to provide an organic electroluminescent device which can be driven with high luminous efficiency in a short wavelength region, particularly in a blue region. .

Another object of the present invention is to provide a fluorescent material having particularly excellent blue light emission characteristics.

[0010]

According to the present invention, there is provided an organic electroluminescent device comprising a substrate having a hole transport layer sandwiched between an anode and a cathode and an organic light emitting layer formed on the substrate. The layer contains an anthracene derivative represented by the following general formula (I).

The fluorescent material of the present invention is characterized by comprising an anthracene derivative represented by the following general formula (I).

[0012]

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In the formula (I), R ¹ , R ² , R ³ , R ⁴ ,
R ⁵ and R ⁶ are hydrogen, halogen, alkyl, aralkyl, alkenyl, allyl, cyano, amino, amide, nitro, acyl, alkoxycarbonyl, carboxyl, alkoxy, alkyl Represents a sulfonyl group or a hydroxyl group, and among these, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, an amino group, an amide group, an acyl group, an alkoxycarbonyl group, an alkoxy group, and an alkylsulfonyl group have a substituent. Is also good. Ar ¹ , Ar ² , Ar ³ and Ar ⁴ represent an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ^{1 to} R ⁶ and Ar ^{1 to} Ar ⁴ may be the same or different from each other. By doping the organic light emitting layer with the anthracene derivative, the luminous efficiency of the organic electroluminescent device can be significantly increased. Since this anthracene derivative is also effective for structurally stabilizing the thin film state of the organic light emitting layer, the long-term stability of the organic electroluminescent device can be improved.

In the present invention, the doping amount of the anthracene derivative is preferably 0.01 to 20% by weight.

The anthracene derivative is preferably doped into the following specific host material.

A compound represented by the following general formula (II):
In particular, compounds wherein X is represented by the following general formula (III) or (IV).

[0017]

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In the formula (II), R ^1A , R ^2A , R ^3A , R ^4A ,
R ^5A and R ^6A represent a hydrogen atom, a halogen atom, an alkyl group,
Aralkyl group, alkenyl group, allyl group, cyano group, amino group, nitro group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylsulfonyl group, α-haloalkyl group, hydroxyl group, even if having a substituent A good amide group, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, wherein R ^{1A to} R ^6A are the same or different. You may. X may have an alkyl group, an alkoxyl group, an alkylcarboxyl group, an aromatic hydrocarbon ring group which may have a substituent, an arylalkoxyl group which may have a substituent, or a substituent Shows a functional group such as an arylcarboxyl group. )

[0019]

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In the formula (III), R ^1B , R ^2B , R ^3B , R ^4B ,
R ^5B represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, a nitro group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group,
an α-haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent. And R ^{1B to} R ^5B may be the same or different from each other. )

[0021]

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(In the formula (IV), R ^1C , R ^2C and R ^3C represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, a nitro group,
Acyl group, alkoxycarbonyl group, carboxyl group,
An alkoxy group, an alkylsulfonyl group, an α-haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or Represents a good aromatic heterocyclic group, R ^{1C to} R ^3C
May be the same or different. A compound represented by the following general formula (V).

[0023]

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In the formula (V), R ^1D , R ^2D , R ^3D , R ^4D ,
R ^5D and R ^6D represent a hydrogen atom, a halogen atom, an alkyl group,
Aralkyl group, alkenyl group, allyl group, cyano group, amino group, nitro group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylsulfonyl group, α-haloalkyl group, hydroxyl group, even if having a substituent A good amide group, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, wherein R ^{1D to} R ^6D are the same or different. You may. A benzimidazole derivative represented by the following general formula (VI).

[0025]

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(Wherein M is Be, Zn, Cd, A
1, Ga, In, Sc, Y, Mg, Ca, Sr, Co,
Represents Cu, Ni, Pd, Sm, Eu or Tb, A represents a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an alkoxycarbonyl group, a carboxyl group, Represents an alkoxy group, a hydroxyl group, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and R ^1E , R ^2E , R ^3E , R ^4E , R ^5E , R ^6E , R ^7E ,
R ^8E has a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, a hydroxyl group, and a substituent. Represents an aromatic hydrocarbon ring group which may be substituted or an aromatic heterocyclic group which may have a substituent, and R ^{1E to} R ^8E may be the same or different from each other. n shows the integer of 1-3. A benzoxazole derivative represented by the following general formula (VII).

[0027]

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((VII) wherein M is Be, Zn, Cd, A
1, Ga, In, Sc, Y, Mg, Ca, Sr, Co,
Represents Cu, Ni, Pd, Sm, Eu or Tb, R ^1F ,
R ^2F , R ^3F , R ^4F , R ^5F , R ^6F , R ^7F , R ^8F are a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, a hydroxyl group, an aromatic optionally substituted hydrocarbon ring group or an optionally substituted aromatic heterocyclic group, R ^1F ~ R ^8F may be the same or different. n shows the integer of 1-3. A distyrylarylene derivative represented by the following general formula (VIII).

[0029]

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(In the formula (VIII), Ar ^1A , Ar ^2A , Ar ^3A ,
Ar ^4A and Ar ^5A represent an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and Ar ^{1A to} Ar ^5A are the same or different. It may be something. )

[0031]

Embodiments of the present invention will be described below in detail.

First, the fluorescent material of the present invention and an anthracene derivative as a dopant doped in the organic light emitting layer of the organic electroluminescent device of the present invention will be described.

In the general formula (I) representing the anthracene derivative according to the present invention, R ^{1 to} R ⁶ are preferably a hydrogen atom, a chlorine atom, a bromine atom, a halogen atom such as an iodine atom, a cyano group or an amino group. , Dimethylamino group,
C1-C6 alkyl group such as nitro group, hydroxyl group, or methyl group and ethyl group which may have a substituent; C1-C6 alkoxy group such as methoxy group and ethoxy group; Methoxycarbonyl And an alkoxycarbonyl group having 1 to 6 carbon atoms such as an ethoxycarbonyl group. Examples of the substituent to be substituted on these include an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; a lower alkoxy group such as a methoxy group; and a substituted amino group such as a dimethylamino group. R ^{1 to} R ⁶ are particularly preferably a hydrogen atom,
Halogen atom, alkyl group having 1 to 6 carbon atoms, 1 to 1 carbon atom
And 6 alkoxy groups.

Ar ^{1 to} Ar ⁴ represent an aromatic hydrocarbon group or an aromatic heterocyclic group which may have a substituent, which may be the same or different. Examples of the aromatic hydrocarbon ring group include phenyl group; alkylphenyl group; alkoxyphenyl group; arylphenyl group; aryloxyphenyl group; alkenylphenyl group; aminophenyl group; naphthyl group; anthryl group; pyrenyl group; An arylalkenyl group such as an ethynyl group, a tolylethynyl group, a biphenylethynyl group, and a naphthylethynyl group is exemplified. Examples of the aromatic heterocyclic group include a thienyl group, a furyl group, a pyrrole group, a pyridyl group, and the like, and those containing an oxygen atom, a nitrogen atom, and a sulfur atom as a hetero atom are preferable, and a 5-membered ring or a 6-membered ring may be used. . When it has a substituent, examples of the substituent include a halogen atom such as a chlorine atom and a bromine atom; an alkyl group having 1 to 6 carbon atoms such as a methyl group and an ethyl group; an amide group; To 6 alkoxy groups; 1 carbon atom such as a methoxycarbonyl group or an ethoxycarbonyl group
To 6 alkoxycarbonyl groups; an amino group which may have a substituent; an aryl group; a heterocyclic group. Ar
^{1 to} Ar ⁴ are particularly preferably an unsubstituted aromatic hydrocarbon group.

In order to synthesize such an anthracene derivative, first, starting from the following general formula (IX), an amino group is subjected to an aromatic substitution reaction through diazotization to give a compound of the following general formula (X). obtain.

Next, a lithiation reagent is reacted therewith to obtain a compound of the following general formula (XI), which is further reduced. After completion of the reaction, the obtained precipitate is separated by filtration and purified by sublimation, whereby the desired anthracene derivative can be obtained.

[0037]

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[0038]

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[0039]

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Specific examples of the anthracene derivative suitable for the present invention are shown in the following Tables 1 to 8, but the present invention is not limited thereto.

[0041]

[Table 1]

[0042]

[Table 2]

[0043]

[Table 3]

[0044]

[Table 4]

[0045]

[Table 5]

[0046]

[Table 6]

[0047]

[Table 7]

[0048]

[Table 8]

[0049]

[Table 9]

[0050]

[Table 10]

[0051]

[Table 11]

[0052]

[Table 12]

[0053]

[Table 13]

Such an anthracene derivative according to the present invention has a high fluorescence intensity in a dispersed state, good light resistance and good heat resistance, and can be obtained by doping such an anthracene derivative into an organic light emitting layer of an organic electroluminescent device. As a result, stable light emission characteristics can be obtained.

The anthracene derivative is a good fluorescent compound which can be used for various fluorescent materials, fluorescent dyes of resins, laser dyes, scintillator dyes, etc. in addition to organic electroluminescent devices.

Hereinafter, the structure of the organic electroluminescent device of the present invention will be described with reference to the drawings.

1 and 2 are cross-sectional views schematically showing examples of the structure of the organic electroluminescent device of the present invention, wherein 1 is a substrate, 2 is an anode, 3 is an organic buffer layer, 4 is a hole transport layer, 5 Represents an organic light emitting layer, 6 represents an electron injection layer, and 7 represents a cathode.

The substrate 1 serves as a support for the organic electroluminescent device, and is made of a quartz or glass plate, a metal plate or a metal foil, a plastic film or a sheet, or the like. Particularly, a glass plate or a plate of a transparent synthetic resin such as polyester, polymethacrylate, polycarbonate, and polysulfone is preferable. When using a synthetic resin substrate, it is necessary to pay attention to gas barrier properties. That is, if the gas barrier property of the substrate is too low, the organic electroluminescent device may be deteriorated by the outside air passing through the substrate, which is not preferable. Therefore, when a synthetic resin substrate is used, it is preferable to secure gas barrier properties by providing a dense silicon oxide film or the like on at least one plate surface.

An anode 2 is provided on a substrate 1. Anode 2
Plays a role of injecting holes into the hole transport layer 4. This anode is usually made of a metal such as aluminum, gold, silver, nickel, palladium, platinum, a metal oxide such as indium and / or tin oxide, a metal halide such as copper iodide, carbon black, or (3-methylthiophene), conductive polymers such as polypyrrole and polyaniline. The formation of the anode 2 is usually
It is often performed by a sputtering method, a vacuum evaporation method, or the like. Also, metal particles such as silver, particles such as copper iodide, carbon black, conductive metal oxide particles,
In the case of a conductive polymer fine powder or the like, the anode 2 can be formed by dispersing in an appropriate binder resin solution and applying the dispersion on the substrate 1. Further, in the case of a conductive polymer, a thin film can be formed directly on the substrate 1 by electrolytic polymerization, or the conductive polymer can be applied on the substrate 1 to form the anode 2 (Appl. Phys. Lett. , 60, 2711, 1992
Year). The anode 2 can have a laminated structure of different materials. The thickness of the anode 2 depends on the required transparency. If transparency is required, increase the visible light transmission,
Usually, it is desirable to be 60% or more, preferably 80% or more. In this case, the thickness of the anode 2 is usually 5 to 1000 nm,
It is preferably about 10 to 500 nm. If opaque, the anode 2 may be the same as the substrate 1. Further, it is also possible to laminate a different conductive material on the anode 2.

The hole transport layer 4 is provided on the anode 2. The condition required for the material of the hole transport layer 4 is that the material has a high hole injection efficiency from the anode and can efficiently transport the injected holes.
Therefore, the ionization potential is small, the transparency to visible light is high, the hole mobility is large, the stability is further improved, and impurities serving as traps are hardly generated at the time of manufacture or use. Required. In addition to the above general requirements, when considering applications for in-vehicle display, the element is required to have further heat resistance. Therefore, the glass transition temperature Tg
Is preferably a material having a value of 70 ° C. or more.

As such a hole transporting material, for example, an aromatic diamine compound linked to a tertiary aromatic amine unit such as 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane (Japanese Unexamined Patent Application Publication No. JP-A-59-194393), 4,4'-
Aromatic amines containing two or more tertiary amines represented by bis [N- (1-naphthyl) -N-phenylamino] biphenyl and having two or more condensed aromatic rings substituted with nitrogen atoms (Japanese Patent Laid-Open No. -234681), an aromatic triamine having a starburst structure as a derivative of triphenylbenzene (US Pat. No. 4,923,774), N, N'-diphenyl-N, N'-bis (3-methylphenyl) biphenyl-4 Aromatic diamines such as 4,4'-diamine (U.S. Pat. No. 4,764,625), α, α,
α ', α'-Tetramethyl-α, α'-bis (4-di-p-tolylaminophenyl) -p-xylene (JP-A-3-269084), triphenyl which is sterically asymmetric as a whole molecule Amine derivatives (JP-A-4-129271), compounds in which a pyrenyl group is substituted with a plurality of aromatic diamino groups (JP-A-4-129271)
No. 175395), an aromatic diamine having a tertiary aromatic amine unit linked by an ethylene group (JP-A-4-264189), and an aromatic diamine having a styryl structure (JP-A-4-264189).
JP-A-290851), those in which aromatic tertiary amine units are linked by a thiophene group (JP-A-4-304466), starburst-type aromatic triamines (JP-A-4-308688), and benzylphenyl compounds (JP-A-4-308688). Japanese Unexamined Patent Publication (Kokai) No. 4-364153), those in which a tertiary amine is linked by a fluorene group (Japanese Unexamined Patent Application Publication No. 5-25473), and triamine compounds (Japanese Unexamined Patent Application Publication No.
-239455), bisdipyridylaminobiphenyl (JP-A-5-320634), N, N, N-triphenylamine derivatives (JP-A-6-1972), aromatic diamines having a phenoxazine structure (particularly JP-A-7-138562), diaminophenylphenanthridine derivatives (JP-A-7-252474), hydrazone compounds (JP-A-2-13862).
No. 311591), silazane compounds (US Pat. No. 4,950,95)
No. 0), silanamine derivatives (JP-A-6-49079), phosphamine derivatives (JP-A-6-25659), and quinacridone compounds. These compounds may be used alone or, if necessary, in combination of two or more.

In addition to the above-mentioned compounds, materials for the hole transport layer 4 include polyvinyl carbazole and polysilane (App
l. Phys. Lett., Vol. 59, p. 2760, 1991), polyphosphazene (JP-A-5-310949), polyamide (JP-A-5-310949), polyvinyltriphenylamine (JP-A-7-310949). No. 53953), a polymer having a triphenylamine skeleton (Japanese Patent Application Laid-Open No. 4-1303065), and a polymer in which triphenylamine units are linked by a methylene group or the like (Synthetic Metals, 55-57, 4163, 1993) ), A polymethacrylate containing an aromatic amine (J. Polym.
Sci., Polym. Chem. Ed., 21, 969, 1983).

The hole transport layer 4 is formed by laminating these hole transport materials on the anode 2 by a coating method or a vacuum evaporation method.

In the case of the coating method, one or more hole transporting materials and, if necessary, additives such as a binder resin or a coating property improving agent which do not trap holes are added and dissolved. A solution is prepared, applied on the anode 2 by a method such as spin coating, and dried to form the hole transport layer 4. In this case, examples of the binder resin include polycarbonate, polyarylate, and polyester.
If the amount of the binder resin is large, the hole mobility is reduced. Therefore, a small amount is desirable, and usually 50% by weight or less is preferable.

In the case of the vacuum evaporation method, the hole transporting material is put into a crucible provided in a vacuum vessel, and the inside of the vacuum vessel is evacuated to about 10 ^-4 Pa by a suitable vacuum pump, and then the crucible is heated. Then, the hole transport material is evaporated to form the hole transport layer 4 on the anode 2 on the substrate 1 placed facing the crucible.

When the hole transport layer 4 is formed,
As an acceptor, a metal complex of an aromatic carboxylic acid and / or
Or metal salts (JP-A-4-320484), benzophenone derivatives and thiobenzophenone derivatives (JP-A-5-29)
No. 5361), fullerenes (JP-A-5-331458) and the like are doped at a concentration of 10 ^-3 to 10% by weight to generate holes as free carriers, thereby enabling low-voltage driving. can do.

The thickness of the hole transport layer 4 is usually 10 to 300 nm.
, Preferably 30 to 100 nm. In order to uniformly form such a thin film, generally, a vacuum deposition method is often used.

In order to improve the contact between the anode 2 and the hole transport layer 4, it is conceivable to provide an anode buffer layer 3 as shown in FIG. The conditions required for the material used for the anode buffer layer 3 are that the contact with the anode 2 is good, a uniform thin film can be formed, and the film is thermally stable, that is, the melting point and the glass transition temperature Tg are high, and the melting point is 30
The glass transition temperature is required to be 0 ° C or higher and 100 ° C or higher. In addition, the ionization potential is low, holes can be easily injected from the anode, and the hole mobility is high. For this purpose, porphyrin derivatives and phthalocyanine compounds (JP-A-63-295695) and star-bust-type aromatic triamines (JP-A-4-3069) have been used.
No. 8688), a hydrazone compound (JP-A-4-320483), an alkoxy-substituted aromatic diamine derivative (JP-A-4-220995), p- (9-anthryl) -N, N-di-p
-Tolylaniline (JP-A-3-111485), polythienylenevinylene and poly-p-phenylenevinylene (JP-A-4-145192), polyaniline (Appl. Phys.
Lett., Vol. 64, p. 1245, 1994) and organic compounds such as sputtered carbon films (JP-A-8-31573).
And metal oxides such as vanadium oxide, ruthenium oxide, and molybdenum oxide (The 43rd Joint Lecture on Applied Physics, 27a-SY-9, 1996).

Examples of the compound often used as the material of the anode buffer layer include a porphyrin compound and a phthalocyanine compound. These compounds may have a central metal or may be non-metallic.

Specific examples of preferred compounds include the following compounds.

Porphine 5,10,15,20-tetraphenyl-21H, 23H-porphine 5,10,15,20-tetraphenyl-21H, 23H-porphine cobalt (II) 5,10,15,20-tetraphenyl -21H, 23H-porphine copper (II) 5,10,15,20-tetraphenyl-21H, 23H-porphine zinc (II) 5,10,15,20-tetraphenyl-21H, 23H-porphine vanadium (IV) Oxide 5,10,15,20-Tetra (4-pyridyl) -21H, 23H-porphine 29H, 31H-Phthalocyanine Copper (II) phthalocyanine Zinc (II) phthalocyanine Titanium phthalocyanine oxide Magnesium phthalocyanine Lead phthalocyanine Copper (II) 4,4 ', 4'',4'''-Tetraaza-29H, 31H-phthalocyanine The anode buffer layer 3 can be formed into a thin film in the same manner as the hole transport layer 4, but when the material of the anode buffer layer is inorganic, , Furthermore, sputtering, electron beam evaporation, plasma C
The VD method can be used.

The anode buffer layer 3 thus formed
Is usually 3 to 100 nm, preferably 10 to 50 nm.

An organic light emitting layer 5 is provided on the hole transport layer 4. The organic light emitting layer 5 is formed of a compound capable of efficiently transporting electrons from the cathode between the electrodes to which an electric field is applied in the direction of the hole transport layer 4.

The electron transporting compound used in the organic light emitting layer 5 has a high electron injection efficiency from the cathode 7 and
The compound must be able to transport the injected electrons efficiently. For that purpose, it is required that the compound has a high electron affinity, a high electron mobility, and is excellent in stability, and hardly generates impurities serving as traps during production or use.

Materials satisfying such conditions include aromatic compounds such as tetraphenylbutadiene (Japanese Patent Laid-Open No.
Metal complex such as aluminum complex of 8-hydroxyquinoline (JP-A-59-194393),
Metal complexes of 10-hydroxybenzo [h] quinoline (JP-A-6-322362), mixed-ligand aluminum chelate complexes (JP-A-5-198377, JP-A-5-198378, JP-A-5-214332) JP-A-6-172751 Cyclopentadiene derivative (JP-A-2-289675), perinone derivative (JP-A-2-289676), oxadiazole derivative (JP-A-2-2176791), bis Styrylbenzene derivatives (JP-A 1-245087,
JP-A-2-222484), perylene derivatives (JP-A-2-18)
Nos. 9890, 3-791), coumarin compounds (JP-A-2-191694, JP-A-3-792), rare earth complexes (JP-A-1-256584), and distyrylpyrazine derivatives (JP-A-Heisei 2-256584). 2-252793), p-phenylene compound (JP-A-3-33183), thiadiazolopyridine derivative (JP-A-3-37292), pyrrolopyridine derivative (JP-A-3-37293), naphthyridine Derivatives (JP-A-3-203982), and silole derivatives (The 70th Annual Meeting of the Chemical Society of Japan, 2D102 and 2D103, 1996).

Specifically, first, 8-quinolinol or a derivative thereof represented by the general formula (II) and an aluminum complex having another ligand can be mentioned.
(II) In the formula, R ^{1A to} R ^6A represent a hydrogen atom, a halogen atom,
Alkyl group, aralkyl group, alkenyl group, allyl group,
A cyano group, an amino group, a nitro group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group, an α-haloalkyl group, a hydroxyl group, an amide group which may have a substituent, and a substituent Represents an aromatic hydrocarbon ring group which may be substituted or an aromatic heterocyclic group which may have a substituent, and R ^{1A to} R ^6A may be the same or different from each other. X is, for example, -R, -Ar,
-OR, -OR ^X Ar, -OAr, -OC (O) R,-
OC (O) Ar, -OP (O) RR ', -OP (O) A
rAr ', -OS (O) RR', -OS (O) ArA
r ', -SAr, -SeAr, -TeAr, -OSiR
R'R ", -OSiArAr'Ar", -OB (OR)
(OR '), -OB (OAr) (OAr') and the like. R, R 'and R "may be the same or different from each other, and represent an alkyl group having 1 to 6 carbon atoms, an alkenyl group, an alkynyl group, an allyl group, or the like.
Ar, Ar ', Ar "may be one which differs be the same as each other, .R ^X indicating the a good aromatic hydrocarbon group or an aromatic heterocyclic group such as a substituted location carbon Number 1
Alkylene group, alkylidene group, etc. which are divalent hydrocarbon groups of 1 to 6;

As such, specifically, bis (2-methyl-8-quinolinolato) (phenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (ortho-cresolato) aluminum (III) Bis (2-methyl-8-quinolinolato) (meta-cresolato) aluminum (III), bis (2-methyl-8-quinolinolato) (para-cresolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (ortho-phenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (meta-phenylphenolato)
Aluminum (III), bis (2-methyl-8-quinolinolato) (para-phenylphenolato) aluminum (II
I), bis (2-methyl-8-quinolinolato) (2,3
-Dimethylphenolato) aluminum (III), bis (2
-Methyl-8-quinolinolato) (2,6-dimethylphenolato) aluminum (III), bis (2-methyl-8-
Quinolinolato) (3,4-dimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato)
(3,5-dimethylphenolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (3,5-di-
tert-butylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,6-diphenylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,4 6-triphenylphenolato) aluminum (III), bis (2-methyl-8)
-Quinolinolato) (2,4,6-trimethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (2,3,6-trimethylphenolato) aluminum (III), bis (2-methyl) -8-quinolinolato) (2,3,5,6-tetramethylphenolato) aluminum (III), bis (2-methyl-8-quinolinolato) (1-naphthrat) aluminum (III), bis (2
-Methyl-8-quinolinolato) (2-naphthrat) aluminum (III), bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum (III),
Bis (2-methyl-8-quinolinolato) (Tris (4,
4-biphenyl) silanolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (ortho-
Phenylphenolato) aluminum (III), bis (2,
4-dimethyl-8-quinolinolato) (para-phenylphenolato) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (meta-phenylphenolato)
Aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-dimethylphenolate) aluminum (III), bis (2,4-dimethyl-8-quinolinolato) (3,5-di- tert-butylphenolato) aluminum (III), bis (2-methyl-4-ethyl-8-)
Quinolinolato) (para-cresolate) aluminum (II
I), bis (2-methyl-4-methoxy-8-quinolinolato) (para-phenylphenolato) aluminum (III)
, Bis (2-methyl-5-cyano-8-quinolinolato) (ortho-cresolato) aluminum (III), bis (2-methyl-6-trifluoromethyl-8-quinolinolato) (2-naphthrat) aluminum (III) And particularly preferred are bis (2-methyl-8-quinolinolato) (2-naphthrat) aluminum (III) and bis (2-methyl-8-quinolinolato) (triphenylsilanolato) aluminum (III). Can be

Further, an aluminum binuclear complex having 8-quinolinol represented by the general formula (V) or a derivative thereof as a ligand may be used. (V) where R ^1D ~
R ^6D represents a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, a nitro group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group,
an α-haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent. And R ^{1D to} R ^6D may be the same or different from each other.

As such, specifically, bis (2-methyl-8-quinolato) aluminum (III) -μ
-Oxo-bis- (2-methyl-8-quinolylato) aluminum (III), bis (2,4-dimethyl-8-quinolato) aluminum (III) -μ-oxo-bis- (2,4
-Dimethyl-8-quinolinolato) aluminum (III), bis (4-ethyl-2-methyl-8-quinolinolato) aluminum (III) -μ-oxo-bis- (4-ethyl-2)
-Methyl-8-quinolinolato) aluminum (III), bis (2-methyl-4-methoxyquinolinolato) aluminum (III) -μ-oxo-bis- (2-methyl-4-methoxyquinolinolato) aluminum (III) III), bis (5-
Cyano-2-methyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis- (5-cyano-2-methyl-8-quinolinolato) aluminum (III), bis (5-
Chloro-2-methyl-8-quinolinolato) aluminum
(III) -μ-oxo-bis- (5-chloro-2-methyl-8-quinolinolato) aluminum (III), bis (2-
Methyl-5-trifluoromethyl-8-quinolinolato)
Aluminum (III) -μ-oxo-bis- (2-methyl-5-trifluoromethyl-8-quinolinolato) aluminum (III) and the like, particularly preferably bis (2-methyl-8-quinolato) aluminum ( III) -μ-oxo-bis- (2-methyl-8-quinolylato) aluminum
(III).

Further, a metal complex of a benzimidazole derivative represented by the general formula (VI) may be used. (VI)
In the formula, M is Be, Zn, Cd, Al, Ga, In, S
c, Y, Mg, Ca, Sr, Co, Cu, Ni, Pd,
A represents Sm, Eu or Tb, and A represents a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, a nitro group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, a hydroxyl group, Represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and R ^{1E to} R ^8E
Has a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, a hydroxyl group, and a substituent. Represents an aromatic hydrocarbon ring group which may be substituted or an aromatic heterocyclic group which may have a substituent, and R ^{1E to} R ^8E may be the same or different. n is an integer of 1 to 3. As such, specifically, (N-phenyl-2-
(O-hydroxyphenyl) benzimidazole zinc complex, (N-methyl-2- (o-hydroxyphenyl) benzimidazole zinc complex, and the like.

Further, a metal complex of a benzimidazole derivative represented by the above general formula (VII) may be used. (VII)
In the formula, M is Be, Zn, Cd, Al, Ga, In, S
c, Y, Mg, Ca, Sr, Co, Cu, Ni, Pd,
Represents Sm, Eu or Tb, wherein R ^{1F to} R ^8F are a hydrogen atom,
Halogen atom, alkyl group, aralkyl group, alkenyl group, allyl group, cyano group, amino group, amide group, nitro group, alkoxycarbonyl group, carboxyl group, alkoxy group, hydroxyl group, aromatic group which may have a substituent Represents a hydrocarbon ring group or an aromatic heterocyclic group which may have a substituent, and R ^{1F to} R ^8F may be the same or different. n is an integer of 1 to 3. Specific examples of such a compound include a benzoxazole derivative and a 2- (o-hydroxyphenyl) benzoxazole zinc complex described in JP-A-6-336586.

Further, a distyryl arylene derivative represented by the above general formula (VIII) may be used. (VII
In the formula (I), Ar ^{1A to} Ar ^5A represent an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent, and It may be single substituted or plural substituted. Ar ^1A
To Ar ^5A may be the same or different.
Specific examples of such a material include those described in Japanese Patent Application Laid-Open No. HEI 9 (1994) -4,4'-bis (2,2'-diphenylvinyl) biphenyl.
Distyrylarylene derivatives described in JP-A-4-332723 are exemplified.

In the present invention, the anthracene derivative represented by the above general formula (I) as a dopant for doping the organic light-emitting layer 5 shows strong fluorescence in a solution state, and the above-described electron transporting compound is used as a host material. When doped, the luminous efficiency of the device can be improved. Further, the anthracene derivative can structurally stabilize the thin film state of the host material, and provides the organic electroluminescent device with long-term stability.

The region to which the anthracene derivative represented by the general formula (I) is doped may be the entire organic light emitting layer 5 or a part thereof. Is preferably 10 ⁻³ to 10 mol%, and the proportion of the anthracene derivative in the organic light emitting layer 5 is preferably 0.01 to 20.0% by weight. When the proportion of the anthracene derivative is less than this range, the effect of doping the anthracene derivative cannot be sufficiently improved, and when the proportion is too large, concentration quenching occurs and sufficient luminance cannot be obtained.

The doping of the organic light emitting layer 5 having the anthracene derivative represented by the general formula (I) may be performed by a coating method or a vacuum evaporation method as follows.

That is, in the case of the coating method, the above-mentioned electron transporting compound, the anthracene derivative represented by the above general formula (I), and if necessary, a binder resin which does not act as an electron trap or a quencher for light emission, An organic light-emitting layer containing an anthracene derivative is prepared by adding and dissolving an additive such as a coating property improving agent such as a leveling agent, coating the solution on the hole transport layer 4 by a method such as spin coating, and drying. 5 is formed. In this case, examples of the binder resin include polycarbonate, polyarylate, and polyester. If the amount of the binder resin is large, the electron mobility is reduced.
The following is preferred.

In the case of the vacuum evaporation method, the above-mentioned electron transporting compound is put in a crucible placed in a vacuum vessel, and the anthracene derivative represented by the general formula (I) is put in another crucible, The inside is 10 ^-6 Torr by a suitable vacuum pump.
After evacuation to about r, each crucible is heated and evaporated at the same time, and an organic light emitting layer 5 is formed on the hole transport layer 4 on the substrate placed facing the crucible. As another method, a mixture of the above materials at a predetermined ratio in advance may be evaporated using the same crucible.

The organic light emitting layer 5 is formed by the coating method or the vacuum evaporation method as described above, and generally, the vacuum evaporation method is employed.

The thickness of the organic light emitting layer 5 thus formed is usually 10 to 200 nm, preferably 30 to 100 nm.
nm.

When such a dopant is doped in the organic light emitting layer, generally, the dopant is uniformly doped in the thickness direction of each organic light emitting layer, but may have a concentration distribution in the film thickness direction. For example, doping may be performed only near the interface with the hole transport layer, or conversely, may be performed only near the cathode interface.

As described above, the present invention relates to the above-mentioned general formula (I)
The organic light emitting layer 5 is doped with an anthracene derivative represented by the following formula, but may be further doped with another fluorescent dye. That is, as described above, for the purpose of improving the luminous efficiency of the device and changing the luminescent color, for example, doping a fluorescent dye for laser such as coumarin using an aluminum complex of 8-hydroxyquinoline as a host material (J. Appl. Phys., 65, 3610, 1989) and so on. The advantages of this method are: 1) improved luminous efficiency by high-efficiency fluorescent dye, 2) variable emission wavelength by selecting fluorescent dye, 3) fluorescent dye that causes concentration quenching can be used, 4) poor thin film properties Fluorescent dyes can also be used. In the present invention, such a method may be employed.

Also, for the purpose of improving the driving life of the device, it is effective to dope a fluorescent dye with the electron transporting material as a host material. For example, using a metal complex such as an aluminum complex of 8-hydroxyquinoline as a host material, a naphthacene derivative represented by rubrene (JP-A-4-335087), a quinacridone derivative (JP-A-5-70773), perylene, etc. By doping a condensed polycyclic aromatic ring (JP-A-5-198377) in a proportion of 0.1 to 10% by weight with respect to a host material, it is possible to greatly improve the light-emitting characteristics of the device, particularly the driving stability. .

In this case, as the host material, for example,
When the organic light emitting layer 5 plays a role, the above-mentioned electron transporting compound is mentioned. When the hole transporting layer 4 plays a role as a host material, the above-mentioned aromatic amine compound and hydrazone compound are mentioned.

In order to further improve the luminous efficiency of the organic electroluminescent device, an electron injection layer 6 is further laminated on the organic luminescent layer 5 if necessary. The compound used for the electron injection layer 6 is required to be capable of easily injecting electrons from the cathode 7 and having a higher electron transporting ability. As such an electron transport material, the electron transport layer material 8
-Hydroxyquinoline aluminum complex, oxadiazole derivative (Appl. Phys. Lett., Vol. 55, p. 1489, 1989, etc.) and a system in which they are dispersed in a resin such as polymethyl methacrylate (PMMA) (Appl. Phys. Lett., 61, 2793
P. 1992), phenanthroline derivatives (JP-A-5-33)
No. 1459), 2-t-butyl-9,10-N, N'-dicyanoanthraquinone diimine (Phys. Stat. Sol. (A), Vol. 142, 48)
9 (1994), n-type hydrogenated amorphous silicon carbide, n-type zinc sulfide, n-type zinc selenide and the like.

The thickness of the electron injection layer 6 is usually 5 to 200 nm.
, Preferably 10 to 100 nm.

The cathode 7 plays a role of injecting electrons into the organic light emitting layer 5. As the material used for the cathode 7, the material used for the anode 2 can be used, but for efficient electron injection, a metal having a low work function is preferable, and tin, magnesium, indium, calcium, A suitable metal such as aluminum or silver or an alloy thereof is used. The thickness of the cathode 7 is generally equal to that of the anode 2. In order to protect the cathode made of a low work function metal, it is effective to further stack a metal layer having a high work function and being stable to the atmosphere to increase the stability of the device.
Metals for this purpose include metals such as aluminum, silver, nickel, chromium, gold, platinum and the like.

In the present invention, in order to improve the contact between the cathode 7 and the electron injection layer 6 or the organic light emitting layer 5 (when the electron injection layer 6 is not provided), an interface layer may be further provided between them. Compounds used in the cathode interface layer include aromatic diamine compounds (JP-A-6-267658), quinacridone compounds (JP-A-6-330031), naphthacene derivatives (JP-A-6-330032), and organic compounds. Silicon compounds (JP-A-6-325871), organic phosphorus compounds (JP-A-5-325872), compounds having an N-phenylcarbazole skeleton (JP-A-8-60144), N-vinylcarbazole polymers ( JP-A-8-60145).

The thickness of the interface layer is usually 2 to 100 nm, preferably 5 to 30 nm.

Instead of providing such an interface layer, a region containing 50% by weight or more of the material of the interface layer may be provided near the cathode interface of the electron injection layer 6 or the organic light emitting layer 5.

FIGS. 1 and 2 show one embodiment of the organic electroluminescent device of the present invention, and the present invention is not limited to those shown in the drawings. For example, it is also possible to stack the cathode 7, the electron injection layer 6, the organic light emitting layer 5, the hole transport layer 4, and the anode 2 in this order on the substrate, that is, as described above. As described above, the organic electroluminescent device of the present invention can be provided between two substrates, at least one of which has high transparency. Similarly, the organic electroluminescent element of FIG. 2 may have a structure in which the constituent layers are stacked in reverse.

The organic electroluminescent device of the present invention can be applied to any of a single device, a device having a structure arranged in an array, and a device having a structure in which an anode and a cathode are arranged in an XY matrix. be able to.

[0102]

The present invention will be described in more detail with reference to Synthesis Examples, Examples and Comparative Examples, but the present invention is not limited to the following Examples unless it exceeds the gist thereof.

Synthesis Example 1 An anthracene derivative (compound No. (1) in Table 1) (XII) represented by the following structural formula was synthesized.

[0104]

Embedded image

First, 8.5 g (36 mmol) of 1,5-diaminoanthraquinone (XIII) having the following structural formula was added to 300 m 3 of benzene.
l, and 9.9 g of sodium nitrite (144 m
mol), followed by dropwise addition of 14 ml of glacial acetic acid. 1 at room temperature
After stirring at 0 ° C for 3 hours at 50 ° C, the mixture was extracted twice with toluene, washed with water, dried over sodium sulfate, and the solvent was distilled off.
Crude purification was performed by column purification using toluene as a solvent. The obtained crude product was recrystallized from acetone to obtain 0.51 g of a diphenyl-substituted product (yield: 3.95%).

[0106]

Embedded image

Next, this diphenyl-substituted product was converted to benzene 30
and 50 ml of ether, and 100 ml of phenyllithium was added dropwise over 30 minutes under a nitrogen atmosphere. After dripping, at room temperature 30
The mixture was stirred for 1 minute under reflux for 1 minute. After cooling, dilute hydrochloric acid was added dropwise on a water bath to neutralize the reaction solution. After neutralization, the organic layer was separated, washed three times with water and once with a saturated saline solution, dried over sodium sulfate, evaporated, and washed with hexane.
0.49 g of a diol was obtained (67.8% yield).

Next, 1.3 g of 50% hydroiodic acid, 50 m of glacial acetic acid
l, a mixed solution of 6% of 50% hypophosphorous acid was heated and stirred to 50 ° C, and the diol obtained above was added thereto. After the addition was completed, the mixture was heated and stirred at 80 ° C. for 20 minutes to complete the reaction. After standing to cool, the deposited precipitate was separated by filtration and sufficiently dried to obtain 0.38 g of yellow crystals.

The crystals were purified by sublimation to give yellow crystals (0.34 g) (yield: 74.3%). The melting point was measured and found to be 240.6 ° C. This compound was analyzed by mass spectrometry and found to have a molecular weight of 482. Further, the compound was confirmed to be the target compound by IR spectrum (shown in FIG. 3) and NMR spectrum (shown in FIG. 4).

A solution obtained by dissolving the anthracene derivative (XII) in a chloroform solvent at a concentration of 1.5 mmol / ml was excited with a mercury lamp (wavelength 350 nm), and the result of fluorescence measurement was 475 nm.

Example 1 An organic electroluminescent device having the structure shown in FIG. 1 was produced by the following method.

A transparent conductive film of indium tin oxide (ITO) deposited on a glass substrate with a thickness of 120 nm (manufactured by Geomatic Corporation; electron beam film-formed product; sheet resistance of 15Ω) was obtained by using a usual photolithography technique and hydrochloric acid etching. Two
The anode 2 was formed by patterning into a stripe having a width of mm. The patterned ITO substrate is cleaned by ultrasonic cleaning with acetone, water cleaning with pure water, and ultrasonic cleaning with isopropyl alcohol, and then dried by nitrogen blowing.
Finally, the substrate was subjected to ultraviolet / ozone cleaning and set in a vacuum evaporation apparatus. After the rough evacuation of the above apparatus is performed by an oil rotary pump, the degree of vacuum in the apparatus is 2 × 10 ⁻⁶ Torr (about 2.7 × 10 ⁻⁴ P
a) Evacuation was performed using an oil diffusion pump equipped with a liquid nitrogen trap until:

The following 4,4'-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (H-1) was placed in a ceramic crucible placed in the above apparatus.
Was heated by a tantalum wire heater around the crucible to perform vapor deposition. At this time, the temperature of the crucible was controlled in the range of 220 to 240 ° C. Degree of vacuum 2.0 × 10 ^-6 Torr (about 2.7 × 1
0 ^-4 Pa), a hole transport layer 4 having a thickness of 60 nm with a deposition time of 2 minutes and 50 seconds.
I got

[0114]

Embedded image

Subsequently, bis (2-methyl-8-quinolato) aluminum (III) -μ-oxo-bis- (2-methyl) represented by the following structural formula was used as the electron transporting compound (host material) of the organic light emitting layer 5. -8-quinolilat) aluminum
_{(III) (C 10 H 9} NO) 2 Al -O-Al (C 10 H 9 N
O) ₂ (E-1) and the anthracene derivative (XII) synthesized in Synthesis Example 1 as a dope dye were each subjected to binary vapor deposition using separate crucibles. At this time, bis (2-methyl-8-quinolato) aluminum (III) -μ-oxo-bis- (2-methyl-8-quinolinato) aluminum (II)
Crucible I) in the range of 210-220 ° C., a crucible of anthracene derivative (XII) was controlled in the range of 160 to 170 ° C., vacuum degree during vapor deposition 2.0 × 10 ^-6 Torr (about 2.6 × 10 ^{- Four}
Pa), the deposition time is 2 minutes 30 seconds, and the organic light-emitting layer 5 having a thickness of 45 nm
Was formed.

The doping amount of the anthracene derivative (XII) was 0.76 mol% based on the host material, and 1.1% by weight in the organic light emitting layer.

[0117]

Embedded image

Further, an 8-hydroxyquinoline complex of aluminum Al (C ₉ H ₆ NO) ₃ (E-2) represented by the following structural formula was continuously used as a material for the electron injection layer. Vapor deposition was performed as in the case. At this time,
The temperature of the crucible is controlled in the range of 270 to 300 ° C, the degree of vacuum during deposition is 2.0 × 10 ^-6 Torr (approximately 2.7 × 10 ^-4 Pa), the deposition time is 1 minute and 40 seconds, and the film thickness is 45 nm. Injection layer 6 was obtained.

[0119]

Embedded image

The above-described hole transport layer 4 and organic light emitting layer 5
The substrate temperature during vacuum deposition of the electron injection layer 6 was kept at room temperature.

Here, the element on which the deposition up to the electron injection layer 6 was performed was once taken out of the vacuum deposition apparatus into the atmosphere, and a 2 mm-wide stripe-shaped shadow mask was used as a cathode deposition mask, and the ITO of the anode 2 was removed. In close contact with the element so as to be orthogonal to the stripe, it is placed in another vacuum deposition apparatus and the degree of vacuum in the apparatus is 2 × 10 ^-6 Torr in the same manner as described above.
(About 2.7 × 10 ⁻⁴ Pa). continue,
As the cathode 7, an alloy electrode of magnesium and silver was vapor-deposited so as to have a film thickness of 44 nm by a binary simultaneous vapor deposition method. Vapor deposition was performed using a molybdenum boat and the degree of vacuum was 1 × 10 ⁻⁵ Torr (about ^1.10 Torr).
3 × 10 ⁻³ Pa), and the deposition time was 3 minutes and 20 seconds. The atomic ratio of magnesium to silver was 10: 1.4. Further,
Using a molybdenum boat, aluminum was stacked on the magnesium-silver alloy film with a thickness of 40 nm without breaking the vacuum of the apparatus, thereby completing the cathode 7. The degree of vacuum during this aluminum deposition was 1.5 × 10 ⁻⁵ Torr (about 2.0 × 10 ⁻³ Pa), and the deposition time was 1 minute and 20 seconds. The substrate temperature during the deposition of the magnesium / silver alloy and aluminum two-layer cathode was kept at room temperature.

As described above, an organic electroluminescent device having a light emitting area of 2 mm × 2 mm was obtained.

The light emission characteristics of this device were examined, and the results are shown in Table 14.
It was shown to. In Table 14, the emission luminance was 250 mA /
The value at a current density of cm ² , the luminous efficiency is the value at 100 cd / m ² ,
The luminance / current is the slope of the luminance-current density characteristic, and the voltage is 100
The values at cd / m ² are shown.

Comparative Example 1 A device was prepared in the same manner as in Example 1 except that the organic light emitting layer was not doped with the anthracene derivative (XII). The light emitting characteristics of this device are shown in Table 14.

Comparative Example 2 Instead of the anthracene derivative (XII), the following 1,4
A device was prepared in the same manner as in Example 1 except that the organic light-emitting layer was doped with 9,10-tetraphenylanthracene (XIV). The light-emitting characteristics of this device are shown in Table 14.

[0126]

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Comparative Example 3 A solution prepared by dissolving the following 1,9,10-triphenylanthracene (XV) at a concentration of 1.5 mmol / ml in a chloroform solvent was excited by a mercury lamp (wavelength 350 nm) to emit fluorescence. As a result, only weak fluorescence of 475 nm was shown.

[0128]

Embedded image

In place of the anthracene derivative (XII), the 1,9,10-triphenylanthracene (X
A device was prepared in the same manner as in Example 1 except that V) was doped into the organic light-emitting layer, and the light-emitting characteristics of this device are shown in Table 14.

Example 2 As an electron transporting compound (host material) of the organic light emitting layer,
The benzimidazole zinc complex (E-
An element was prepared in the same manner as in Example 1 except that 3) was used, and Table 14 shows the light emission characteristics of this element.

[0131]

Embedded image

The crucible of the benzimidazole zinc complex at the time of vapor deposition of the organic light emitting layer was controlled in the range of 200 to 210 ° C., and the crucible of the anthracene derivative (XII) was controlled within the range of 150 to 160 ° C. Is 2.5 × 10 ^-6 Torr (about 3.
3 × 10 ⁻⁴ Pa), the deposition time was 2 minutes and 20 seconds, and an organic light emitting layer having a thickness of 45 nm was formed. The doping amount of the anthracene derivative (XII) was 0.90 mol% with respect to the host material, and was 1.2% by weight in the organic light emitting layer.

Comparative Example 4 A device was prepared in the same manner as in Example 2 except that the organic light emitting layer was not doped with the anthracene derivative (XII).
Table 14 shows the emission characteristics of this device.

Example 3 As the electron transporting compound (host material) of the organic light emitting layer,
A device was prepared in the same manner as in Example 1, except that distyrylbiphenyl (E-4) represented by the following structural formula was used. The emission characteristics of this device are shown in Table 14.

[0135]

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The crucible of distyrylbiphenyl at the time of vapor deposition of the organic light emitting layer is controlled in the range of 150 to 170 ° C., and the crucible of the anthracene derivative (XII) is controlled within the range of 150 to 160 ° C., and the degree of vacuum at the time of vapor deposition is controlled. 2.5 × 10 ^-6 Torr (about 3.3 × 10
^-4 Pa), the deposition time was 2 minutes and 20 seconds, and an organic light emitting layer having a thickness of 45 nm was formed. The doping amount of the anthracene derivative (XII) is
1.3 mol% with respect to the host material, and 1.4% by weight in the organic light emitting layer.

Comparative Example 5 A device was prepared in the same manner as in Example 3, except that the organic light emitting layer was not doped with the anthracene derivative (XII).
Table 14 shows the emission characteristics of this device.

Example 4 As an electron transporting compound (host material) of the organic light emitting layer,
An aluminum complex of 2-methyl-8-hydroxyquinaldine and triphenylsilanol represented by the following structural formula (E
An element was prepared in the same manner as in Example 1 except that -5) was used, and Table 14 shows the light emission characteristics of this element.

[0139]

Embedded image

The crucible of the aluminum complex of triphenylsilanol at the time of vapor deposition of the organic light emitting layer is in the range of 180 to 200 ° C., and the crucible of the anthracene derivative (XII) is in the range of 150 to 16 ° C.
Each is controlled within the range of 0 ° C, and the degree of vacuum during evaporation is 2.0 ×
10 ^-6 Torr (about 2.7 × 10 ^-4 Pa), deposition time is 2 minutes and 50 seconds,
An organic light emitting layer having a thickness of 45 nm was formed. Anthracene derivative
The doping amount of (XII) was 1.0 mol% based on the host material, and 1.3% by weight in the organic light emitting layer.

Comparative Example 6 A device was prepared in the same manner as in Example 4 except that the organic light emitting layer was not doped with the anthracene derivative (XII).
Table 14 shows the emission characteristics of this device.

[0142]

[Table 14]

From Table 14, it is clear that the fluorescent material and the organic electroluminescent device of the present invention have excellent light emitting characteristics.

[0144]

As described in detail above, the fluorescent material of the present invention has excellent short-wavelength light-emitting characteristics, particularly blue light-emitting characteristics, and is excellent in light resistance and heat resistance.

Since the organic electroluminescent device of the present invention has such an organic light-emitting layer containing the anthraquinone derivative of the fluorescent material of the present invention, short-wavelength visible light-emitting characteristics, in particular, blue light-emitting characteristics and organic light-emitting characteristics. The stability of the thin film structure is improved, and stable and high emission characteristics can be obtained over a long period.

Accordingly, the organic electroluminescent device according to the present invention can be used as a light source (for example, a light source of a copier, a liquid crystal display or an instrument) utilizing the features of a flat panel display (for example, for an OA computer or a wall-mounted television) or a surface light emitter. It can be applied to various types of backlight sources, display boards, and sign lights, and its technical value is extremely large.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view showing one example of an embodiment of an organic electroluminescent device of the present invention.

FIG. 2 is a schematic sectional view showing another example of the embodiment of the organic electroluminescent device of the present invention.

FIG. 3 shows IR of an anthracene derivative synthesized in Synthesis Example 1.
It is a spectrum.

FIG. 4 shows an NM of an anthracene derivative synthesized in Synthesis Example 1.
It is an R spectrum.

[Explanation of symbols]

 Reference Signs List 1 substrate 2 anode 3 anode buffer layer 4 hole transport layer 5 organic light emitting layer 6 electron injection layer 7 cathode

Claims (9)

[Claims] 1. An organic electroluminescent device in which a hole transport layer and an organic light emitting layer sandwiched between an anode and a cathode are formed on a substrate, wherein the organic light emitting layer is represented by the following general formula (I). An organic electroluminescent device comprising an anthracene derivative. Embedded image (In the formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group,
Represents an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group or a hydroxyl group, and among these, an alkyl group, an aralkyl group, an alkenyl Group, allyl group, amino group, amide group,
The acyl group, alkoxycarbonyl group, alkoxy group, and alkylsulfonyl group may have a substituent. Ar
¹ , Ar ² , Ar ³ and Ar ⁴ represent an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ^{1 to} R ⁶ and Ar ^{1 to} Ar ⁴
May be the same or different from each other. ) 2. The organic electroluminescent device according to claim 1, wherein the content of the anthracene derivative in the organic light emitting layer is 0.01 to 20% by weight. 3. The organic electroluminescent device according to claim 1, wherein the anthracene derivative is contained in a compound represented by the following general formula (II). Embedded image (Wherein R ^1A , R ^2A , R ^3A , R ^4A , R ^5A , R
^6A is a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group,
Nitro group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylsulfonyl group, α-
A haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
R ^{1A to} R ^6A may be the same or different from each other. X may have an alkyl group, an alkoxyl group, an alkylcarboxyl group, an aromatic hydrocarbon ring group which may have a substituent, an arylalkoxyl group which may have a substituent, or a substituent Shows a functional group such as an arylcarboxyl group. ) 4. The organic electroluminescent device according to claim 3, wherein X in the general formula (II) is represented by the following general formula (III) or (IV). Embedded image (Wherein, R ^1B , R ^2B , R ^3B , R ^4B , and R ^5B represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, a nitro group,
Acyl group, alkoxycarbonyl group, carboxyl group,
An alkoxy group, an alkylsulfonyl group, an α-haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or Represents a good aromatic heterocyclic group, R ^{1B to} R ^5B
May be the same or different. ) (In the formula (IV), R ^1C , R ^2C , R ^3C represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, a nitro group, an acyl group, an alkoxycarbonyl group Having a carboxyl group, an alkoxy group, an alkylsulfonyl group, an α-haloalkyl group, a hydroxyl group, an amide group optionally having a substituent, an aromatic hydrocarbon ring group optionally having a substituent or a substituent. ^{Represents an} optionally substituted aromatic heterocyclic group, and R ^{1C to} R ^3C may be the same or different from each other.) 5. The organic electroluminescent device according to claim 1, wherein the anthracene derivative is contained in a compound represented by the following general formula (V). Embedded image (Wherein R ^1D , R ^2D , R ^3D , R ^4D , R ^5D , R
^6D is a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group,
Nitro group, acyl group, alkoxycarbonyl group, carboxyl group, alkoxy group, alkylsulfonyl group, α-
A haloalkyl group, a hydroxyl group, an amide group which may have a substituent, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
R ^{1D to} R ^6D may be the same or different from each other. ) 6. The organic electroluminescent device according to claim 1, wherein the anthracene derivative is contained in a benzimidazole derivative represented by the following general formula (VI). Embedded image (In the formula (VI), M is Be, Zn, Cd, Al, Ga, I
n, Sc, Y, Mg, Ca, Sr, Co, Cu, Ni,
Represents Pd, Sm, Eu or Tb, wherein A is a halogen atom,
Alkyl group, aralkyl group, alkenyl group, allyl group,
Cyano group, amino group, amide group, nitro group, alkoxycarbonyl group, carboxyl group, alkoxy group, hydroxyl group, aromatic hydrocarbon ring group which may have a substituent or aromatic which may have a substituent Represents a group heterocyclic group,
R ^1E , R ^2E , R ^3E , R ^4E , R ^5E , R ^6E , R ^7E , R ^8E
Hydrogen atom, halogen atom, alkyl group, aralkyl group,
Having an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, a hydroxyl group, an aromatic hydrocarbon ring group which may have a substituent or a substituent. And R ^{1E to} R ^8E may be the same or different from each other. n shows the integer of 1-3. ) 7. The organic electroluminescent device according to claim 1, wherein the anthracene derivative is contained in a benzoxazole derivative represented by the following general formula (VII). Embedded image ((VII) In the formula, M is Be, Zn, Cd, Al, Ga, I
n, Sc, Y, Mg, Ca, Sr, Co, Cu, Ni,
Represents Pd, Sm, Eu or Tb, and represents R ^1F , R ^2F , R ^3F ,
R ^4F , R ^5F , R ^6F , R ^7F , R ^8F are a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group, an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an alkoxycarbonyl group, Carboxyl group, alkoxy group,
A hydroxyl group, an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
R ^{1F to} R ^8F may be the same or different from each other. n shows the integer of 1-3. ) 8. The organic electroluminescent device according to claim 1, wherein the anthracene derivative is contained in a distyryl arylene derivative represented by the following general formula (VIII). Embedded image (In the formula (VIII), Ar ^1A , Ar ^2A , Ar ^3A , Ar ^4A , Ar
^5A represents an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent,
r ^{1A to} Ar ^5A may be the same or different from each other. ) 9. A fluorescent material comprising an anthracene derivative represented by the following general formula (I). Embedded image (In the formula (I), R ¹ , R ² , R ³ , R ⁴ , R ⁵ and R ⁶ represent a hydrogen atom, a halogen atom, an alkyl group, an aralkyl group,
Represents an alkenyl group, an allyl group, a cyano group, an amino group, an amide group, a nitro group, an acyl group, an alkoxycarbonyl group, a carboxyl group, an alkoxy group, an alkylsulfonyl group or a hydroxyl group, and among these, an alkyl group, an aralkyl group, an alkenyl Group, allyl group, amino group, amide group,
The acyl group, alkoxycarbonyl group, alkoxy group, and alkylsulfonyl group may have a substituent. Ar
¹ , Ar ² , Ar ³ and Ar ⁴ represent an aromatic hydrocarbon ring group which may have a substituent or an aromatic heterocyclic group which may have a substituent. R ^{1 to} R ⁶ and Ar ^{1 to} Ar ⁴
May be the same or different from each other. )