JPH07211457A - Organic thin-film electroluminescent element - Google Patents

Abstract

PURPOSE:To allow an organic thin-film electroluminescent element to emit light of wavelengths longer than those of yellow light with high efficiency by having an organic thin film sandwiched between a pair of transparent electrodes. CONSTITUTION:A compound used in an organic thin film has a structure represented by the general formula and forms an organic thin-film electroluminescent element. To fabricate the element, ITO is vapor deposited over a glass substrate to form a transparent support substrate, and N,N'- diphenyl N,N'-bis(3-methylphenyl)-4,4'-diamine is vapor deposited to form a hole injection transporting layer. The compound represented by the formula, i.e., tris(8-hydroxyquinolino) aluminum, is vapor deposited to form a light emitting layer for coating the transporting layer. Then magnesium serving as cathode is vapor deposited over the transporting layer and a DC voltage is applied to an ITO electrode serving as anode and to a magnesium-silver electrode serving as cathode, to achieve stable emission of reddish orange light in the atmosphere, thereby enabling a brightness of 350cd/m<2> to be obtained at 7V.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic thin film EL element used for a flat light source or a display.

[0002]

2. Description of the Related Art Focusing on the high fluorescence efficiency of organic compounds, research on devices utilizing the EL performance of organic compounds has been conducted for a long time. For example, W. Helfrich, W. G.
Schneider uses anthracene single crystal and emits blue light (J. Chem. Phys., 44, 2).
902 (1966)). In addition, P. S. Vincett
And Barlow et al. Manufacture a light emitting device by a vacuum evaporation method of a condensed polycyclic compound (Thin Soli.
d Films, 99, 171 (1982)). However, none of them were at a practical level because the driving voltage was high and the emission intensity and emission efficiency were low.

In recent years, however, an organic thin film EL element (chemical and industrial) having a laminated structure in which an organic compound that emits strong fluorescence is used in an organic light emitting layer and a charge injection transporting organic compound is used in an organic injection transporting layer. , 42, 2023,
1989) or an organic thin film E composed of an organic thin film in which a fluorescent emitting organic compound is mixed with a charge injecting and transporting organic compound.
L element (Applied physics, 61 volumes, 1044 pages, 1992)
Has been reported and is attracting strong interest. These organic thin films E
The L element is several hundred cd / m ² at a DC voltage of 10V.
The maximum luminous efficiency is about 1 lm / W, which is close to the practical level.

An organic thin film EL element in which an organic light emitting layer and an organic charge injecting and transporting layer are laminated and an organic thin film EL element comprising a thin film in which a fluorescent organic compound is mixed in a charge injecting organic compound are 100 cd / d when a direct current of 10 V is applied. Bright emission of m ² or more is exhibited. However, a device that emits light having a wavelength longer than the wavelength of yellow is a tris (8-
A device in which a thin film in which a dicyanomethylenepyran derivative is mixed with hydroxyquinolino) aluminum is used as a light emitting layer (J.
Appl. Phys. , 65, 3610 (19
89)), and an element using a perylene thin film as a light emitting layer reported by Adachi et al. (Jpn. J. Appl. Phy).
s. No. 27, L269 (1988) is known, but the luminous efficiency is insufficient, the luminous life is short, and it is difficult to stably emit light in the atmosphere.

The organic thin film EL device can use a laser dye as a light emitting material (Polymer Society of Japan, Volume 6, Polymer Functional Material Series, "Optical Functional Material", pp236, Kyoritsu Shuppan (1991)), 570 nm or more. Xanthene-based compounds and oxazine-based compounds are known as laser dyes having the fluorescence wavelength of (Okawara et al., “Functional dyes”, pp.172, Kodansha Scientific (1
992)).

However, Utsugi et al. Used tris (8-
An organic thin film EL device using a light emitting layer doped with hydroxyquinolino) aluminum was prepared.
It is reported that no light emission from 10 was obtained (Shingaku Gijutsu, OME89-46 (1989)).

Further, in an organic thin film EL device using a thin film in which rhodamine 6G, which is a xanthene compound, is dispersed in poly (p-phenylene vinylene) as a light emitting layer, which is reported in JP-A-5-29078, 100 cd /
Light emission of m ² or more is not obtained.

[0008]

In displaying multi-color or full-color, not only short-wavelength light in the visible region but also long-wavelength component is indispensable. Therefore, it is very important for practical use of the organic thin film EL element to further improve the luminous efficiency of the element that emits light having a wavelength longer than that of yellow and reduce the deterioration rate. However, it is difficult to solve these problems with the conventional technology.

As a result of intensive research for solving the conventional problems, in an organic thin film EL device composed of a single or plural layers of organic thin films supported by a pair of electrodes, a thin film containing a specific oxazine-based compound. By an organic thin film EL element characterized in that at least one layer is provided,
I have found something to be achieved.

[0010]

[Means for Solving the Problems] 1) Organic thin film E of the present invention
The L element has a structure in which an organic thin film is held between a pair of electrodes, at least one of which is transparent, and is represented by the general formula (1)

[Chemical 5] It is characterized by containing at least one compound represented by 2) Alternatively, an organic layer including a light emitting layer between a pair of electrodes, at least one of which is transparent, and optionally including at least one charge injecting and transporting layer such as a hole injecting and transporting layer and an electron injecting and transporting layer. The thin film EL device is characterized in that the light emitting layer contains at least one compound represented by the general formula (1). 3) Further, among the compounds represented by the general formula (1), particularly the general formula (2)

[Chemical 6] It is especially preferred to use the compounds shown. (In the general formulas (1) and (2), R1 and R2 are independently hydrogen, fluorine, chlorine, cyano group, carboxyl group, acyl group, alkyl group, fluoroalkyl group, aryl group, alkyloxycarbonyl group, and benz group. It is an imidazolyl group, a benzoxazolyl group, or a benzthiazolyl group, and R1 and R2 may combine with each other to form a saturated or unsaturated five-membered or six-membered ring, and R3 and R4 each independently represent hydrogen. Or an alkyl group, R3 and R
4 may combine with each other to form an unsaturated 6-membered ring.
R5 is a hydroxyl group, an alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an acylamino group, a pyrazolyl group, a triazolyl group, or a morpholino group,
R6 is hydrogen and the amino nitrogen of R5 may combine with R4 to form a pyrrolidine ring or piperidine ring, or the amino nitrogen of R5 may combine with R4 and R6 to form a julolidine ring. Good. L1 to L3
Are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, L4 is hydrogen, L1 and L2, L3 and L
4 may combine with each other to form a 6-membered ring including nitrogen atoms adjacent to L2 and L3).

The compound represented by the general formula (1) used in the present invention is shown in more detail below. That is, R1 and R2 are each independently hydrogen, fluorine, chlorine, cyano group, carboxy group; acyl group such as formyl group, acetyl group, benzoyl group, cinnamoyl group; methyl group, ethyl group, n-
Alkyl groups such as propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group and cyclohexyl group; fluoroalkyl groups such as trifluoromethyl group and pentafluoroethyl group; Methylphenyl group, ethylphenyl group, t-butylphenyl group, fluorophenyl group, difluorophenyl group, cyanophenyl group, aminophenyl group, carboxyphenyl group, methoxyphenyl group, ethoxyphenyl group, t-butoxyphenyl group, trifluoro Aryl groups such as methylphenyl group, acetylaminophenyl group, methoxycarbonylphenyl group, ethoxycarbonylphenyl group and t-butoxycarbonylphenyl group; alkyloxy groups such as methoxycarbonyl group, ethoxycarbonyl group and t-butoxycarbonyl group Bonyl group; Benzimidazolyl group such as benzimidazolyl group or N-methylbenzimidazolyl group; Benzoxazolyl group such as benzoxazolyl group or methylbenzoxazolyl group; or benzthiazolyl group, fluorobenzthiazolyl group, A benzthiazolyl group such as a difluorobenzthiazolyl group;
R1 and R2 may combine with each other to form a saturated or unsaturated five-membered or six-membered ring such as a cyclopentane ring or a benzene ring. R3 and R4 are hydrogen or a methyl group,
An alkyl group such as an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group or a t-butyl group. R3 and R4 may be bonded to each other to form an unsaturated 6-membered ring such as a benzene ring. R5 is a hydroxyl group; a methoxy group, an ethoxy group, an n-propoxy group, an i-propoxy group, an n-butoxy group, an i-butoxy group, an s-butoxy group, a t-butoxy group, or another alkoxy group; an amino group; a methylamino group. , Ethylamino group, n-propylamino group, i-propylamino group,
Alkylamino groups such as n-butylamino group, i-butylamino group, s-butylamino group, t-butylamino group, cyclohexylamino group; dimethylamino group, diethylamino group, di-n-propylamino group, di-i-propylamino group Group, di-n-butylamino group, di-i-butylamino group, di-s-butylamino group, di-t-butylamino group, methylethylamino group, methyl-n-propylamino group, methyl-i-propylamino group, methyl- n-butylamino group, methyl-i-butylamino group, methyl-s-butylamino group, methyl-t-butylamino group, methylcyclohexylamino group, ethyl-n-propylamino group, ethyl-i-propylamino group, ethyl-n-butyl Amino group, ethyl-i-butylamino group,
A dialkylamino group such as an ethyl-s-butylamino group or an ethyl-t-butylamino group; an acylamino group such as an acetylamino group; a pyrazolyl group such as a pyrazolyl group, a methylpyrazolyl group or a dimethylpyrazolyl group;
A triazolyl group such as a triazolyl group, a dimethyltriazolyl group or a methylphenyltriazolyl group; or a morphonyl group, R6 is hydrogen, and the amino nitrogen of R5 is bonded to R4 to form a five-membered pyrrolidine ring or a hexagonal ring. A membered piperidine ring may be formed, or the amino nitrogen of R5 may combine with R4 and R6 to form a julolidine ring.

The following compounds can be mentioned as specific examples of the compound represented by the formula (1).

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

[Chemical 11]

[Chemical 12]

[Chemical 13]

[Chemical 14]

[Chemical 15]

[Chemical 16]

Further, the compound represented by the general formula (2) is shown in detail below. That is, L1 to L3 are each independently hydrogen or methyl group, ethyl group, n-propyl group, i-propyl group, n-butyl group, i-butyl group, s-butyl group, t-butyl group, cyclohexyl group, etc. L4 is hydrogen, L1 and L2 and L3 and L are
4 may combine with each other to form a julolidine ring.
Specific examples of these compounds are shown in formulas (3), (4) and (5).

The structure of the organic thin film EL element of the present invention has various modes such as an AC drive type and a DC drive type, but the following description will be given for the DC drive type. In the case of a DC drive type, the structure of the organic thin film EL element of the present invention is basically a pair of electrodes, one of which is transparent or semitransparent (anode and cathode).
The light emitting layer is sandwiched between them, and a hole injecting and transporting layer and an electron injecting and transporting layer may be interposed therebetween as necessary. Specifically, (A) anode / light emitting layer / cathode, (B)
Anode / hole injection / transport layer / light emitting layer / cathode, (C) anode / light emitting layer / electron injection / transport layer / cathode, (D) anode / hole injection / transport layer / light emitting layer / electron injection / transport layer / cathode, etc. The configuration can be mentioned. The hole injecting and transporting layer and the electron injecting and transporting layer are not always necessary, but the presence of these layers further improves the light emitting performance.

The compound represented by the above general formula (1) can be suitably used as a light emitting layer in the organic thin film EL device of the present invention. When used as a light emitting layer, these compounds may be used as they are, or may be mixed with other compounds such as an organic charge injecting and transporting material. The thin film made of these compounds can be formed by a known method such as a vapor deposition method, a spin coating method, or a casting method. As a specific example, as disclosed in JP-A-59-194393, a binder such as a resin and the compound are dissolved in a solvent,
A method of forming a thin film by a spin coating method or the like can be mentioned. The thin film of the light emitting layer thus formed is not particularly limited and may be appropriately selected depending on the situation, but is usually selected in the range of 5 nm to 5000 nm.

The light emitting layer in this organic thin film EL element is
(A) An injection function capable of injecting holes from the anode or the hole injecting and transporting layer and injecting electrons from the cathode or the electron injecting and transporting layer when an electric field is applied, (b)
It has the function of transporting the injected charges (electrons and holes) by the force of the electric field, and (c) the function of providing a field for recombination of electrons and holes inside the light-emitting layer and connecting it to light emission. ing.

Further, it is preferable that all of the elements having the above-mentioned constitution are supported by a substrate, and there is no particular limitation on the substrate, and those conventionally used for organic thin film EL elements such as glass, A transparent plastic, quartz, or the like can be used.

As the anode in this organic thin film EL device, those having a high work function (4 eV or more) metal, alloy, electrically conductive compound or a mixture thereof as an electrode substance are preferably used. Specific examples of such an electrode material include metals such as Au, CuI, ITO, SnO ₂ and Z.
Conductive transparent materials such as nO and organic conductive compounds such as polyaniline can be used. The anode is formed by vapor deposition, sputtering, coating or the like of these electrode substances.
It can be produced by forming a thin film. When the emitted light is taken out from this electrode, it is desirable that the transmittance is higher than 10%, and the sheet resistance of the electrode is preferably several tens Ω / square or less. Further, although the film thickness depends on the material, a value in the range of usually 10 nm to 1 μm, preferably 10 to 200 nm is selected.

On the other hand, as the cathode, a material having a low work function (4 eV or less), an alloy, an electrically conductive compound or a mixture thereof as an electrode substance is used. Specific examples of such an electrode material include sodium, sodium-potassium alloy, calcium, magnesium, lithium, lithium / aluminum alloy, magnesium / silver mixture, Al / AlO ₂ , indium and the like.
The cathode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. Further, the sheet resistance as an electrode is preferably several tens Ω / square or less, and the film thickness is usually selected in the range of 10 nm to 1 μm, preferably 50 to 200 nm. In this organic thin film EL element, it is convenient that either the anode or the cathode is transparent or semi-transparent to allow the emitted light to pass therethrough, so that the emission efficiency of the emitted light is good.

The structure of the organic thin film EL element of the present invention has various modes as described above, and the hole injecting and transporting layer in the organic thin film EL element having the above-mentioned structure (B) or (D) is positive. A layer composed of a hole-transporting compound, which has a function of transmitting holes injected from the anode to the light-emitting layer, and the hole-injecting / transporting layer is interposed between the anode and the light-emitting layer to lower the layer. Many holes are injected into the light emitting layer by the electric field, and moreover, the electrons injected from the cathode or the electron injecting and transporting layer into the light emitting layer are generated by the barrier of electrons existing at the interface between the light emitting layer and the hole injecting and transporting layer. The element is excellent in light emission performance because it is accumulated near the interface in the light emitting layer and the light emission efficiency is improved.

The hole transport compound used in the hole injecting and transporting layer is disposed between two electrodes to which an electric field is applied, and when holes are injected from the anode, the holes are appropriately emitted. A compound capable of transmitting to, for example, 10 ⁴ to 10 ⁶ V
At least 10 ^-6 cm ² / V · when an electric field of / cm is applied.
Those having a hole mobility of second are preferable. The hole transporting compound is not particularly limited as long as it has the above-mentioned preferable properties, and is conventionally used as a hole charge transporting material in photoconductive materials and organic thin film EL devices. Any known material used for the hole injecting and transporting layer can be selected and used.

Examples of the charge transport material include triazole derivatives (described in US Pat. No. 3,112,197) and oxadiazole derivatives (US Pat. No. 3,189,447). Described), imidazole derivatives (described in Japanese Patent Publication No. 37-16096, etc.), polyarylalkane derivatives (US Pat. Nos. 3,615,402 and 3,820,98).
No. 9, No. 3,542,544, Japanese Patent Publication No. 4
No. 5-555, No. 51-10983, No. 51-93224, No. 55-17105.
56-4148, 55-108667, 55-156953, 56-36656.
Those described in Japanese Patent Publication No.), pyrazoline derivatives and pyrazolone derivatives (US Pat. Nos. 3,180,729, 4,278,746 and JP-A-55-88).
064, 55-88065, 49-1.
05537, 55-51086, 56.
-80051 gazette, the same 56-88141 gazette, the same 5
No. 7-45545, No. 54-112637,
55-74546), phenylenediamine derivatives (U.S. Pat. No. 3,615,404, Japanese Patent Publication No. 51-10105, 46-37).
12, JP-A-47-25336, JP-A-54-
No. 53435, No. 54-110536, No. 5
Nos. 4,119,925 and the like), arylamine derivatives (US Pat. Nos. 3,567,450, 3,180,703, and 3,240,5).
No. 97, No. 3,658,520, No. 4,
No. 232,103, No. 4,175,961, No. 4,012,376, Japanese Patent Publication No. 49-35.
702, 39-27577 and JP-A-55.
No. 144250, No. 56-119132,
No. 56-22437, West German Patent No. 1,110,5
No. 18, etc.), amino-substituted chalcone derivatives (such as those described in US Pat. No. 3,526,501), oxazole derivatives (US Pat. No. 3,2).
57,203) and the like, styrylanthracene derivatives (as described in JP-A-56-46234), fluorenone derivatives (JP-A-54-1).
10837) and hydrazone derivatives (U.S. Pat. No. 3,717,462, Japanese Patent Laid-Open No. Sho 5).
No. 4-59143, No. 55-52063, No. 55-52064, No. 55-46760,
No. 55-85495, No. 57-11350, No. 57-148749, etc.) and stilbene derivatives (JP-A-61-210363).
No. 61-228451 and No. 61-146.
42 publication, 61-72255 publication, 62-47.
No. 646, No. 62-36674, No. 62-1
No. 0652, No. 62-30255, No. 60-
No. 93445, No. 60-94462, No. 60
Nos. -174749 and 60-175052).

These compounds can be used as a hole transfer compound, but the following porphyrin compounds (described in JP-A-63-295695)
And aromatic tertiary amine compounds and styrylamine compounds (US Pat. No. 4,127,412;
No. 3-27033, No. 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.
Those described in JP-A-95695), and particularly preferably the aromatic tertiary amine compound. Typical examples of the porphyrin compound include porphyrin; 5,1
0,15,20-tetraphenyl-21H, 23H-porphyrin copper (II); 5,10,15,20-tetraphenyl-21H, 23H-porphyrin zinc (II);
5,10,15,20-Tetrakis (pentafluorophenyl) -21H, 23H-porphyrin; Silicon phthalocyanine oxide; Aluminum phthalocyanine chloride; Phthalocyanine (metal free); Dilithium phthalocyanine; Copper tetramethylphthalocyanine; Copper phthalocyanine; Chromium phthalocyanine; Zinc phthalocyanine;
Lead phthalocyanine; titanium phthalocyanine oxide; magnesium phthalocyanine; copper octamethylphthalocyanine; and the like.

Representative examples of the aromatic tertiary compound and the styrylamine compound include N, N, N ', N',-
Tetraphenyl-4,4'-diaminobiphenyl; N,
N'-diphenyl-N, N'-di (3-methylphenyl) -4,4'-diaminobiphenyl (TPD); 2,
2-bis (4-di-p-tolylaminophenyl) propane; 1,1-bis (4-di-p-tolylaminophenyl) cyclohexane; N, N, N ', N',-tetra-p-tolyl -4,4'-Diaminobiphenyl; 1,1
-Bis (4-di-p-tolylaminophenyl) -4-phenylcyclohexane; bis (4-dimethylamino-2)
-Methylphenyl) phenylmethane; N, N'-diphenyl-N, N'-di (4-methoxyphenyl) -4,
4'-diaminobiphenyl; N, N'-tetraphenyl-4,4'-diaminobiphenyl ether; 4,4'-
Bis (diphenylamino) quadriphenyl; N,
N, N-tri (p-tolyl) amine; 4- (di-p-tolylamine) -4 '-[4 (di-p-tolylamine) styryl] stilbene; 4-N, N-diphenylamino-
(2-diphenylvinyl) benzene; 3-methoxy-
4′-N, N-diphenylaminostilbene; N-phenylcarbazole and the like.

The hole injecting and transporting layer in the above organic thin film EL device may be composed of one or two or more of these hole transporting compounds, or may be composed of a compound different from the above layer. It may be a laminate of the hole injection transport layer.

On the other hand, the electron injecting and transporting layer in the organic thin film EL element having the above-mentioned constitution (C) or (D) is made of an electron transmitting compound and has a function of transmitting electrons injected from the cathode to the light emitting layer. have. There is no particular limitation on such an electron transfer compound, and any compound can be selected and used from conventionally known compounds.

Preferred examples of the electron transfer compound include:

[Chemical 17] Nitro-substituted fluorenone derivatives, such as

[0028]

[Chemical 18] Thiopyran oxide derivatives such as

[0029]

[Chemical 19] And other diphenylquinone derivatives ["Polymer Preprints, Japan", Volume 37, No. 9, page 681 (1988)
Year)], etc.,

Or

[Chemical 20] And other compounds [Journal of Applied Physics, Vol. 27,
Those described on page 269 (1988), etc.]

Alternatively, anthraquinodimethane derivative (JP-A-57-149259 and JP-A-58-5545).
No. 0, No. 61-225151, No. 61-23
3750, 63-104061, etc.), fluorenylidene methane derivative (Japanese Patent Laid-Open Publication No.
No. 0-69657, No. 61-143764,
No. 61-148159, etc.), anthrone derivatives (Japanese Patent Laid-Open No. 61-225151, No. 6-225151).
Nos. 1-233750 and the like), JP-A-5
2,5-bis (5,7-di-t-pentyl-2-benzoxazoyl) described in JP-A 9-194393.
-1,3,4-thiadiazole, 4,4'-bis (5,
7-t-pentyl-2-benzoxazolyl) stilbene, 2,5-bis (5,7-di-t-pentyl-2-benzoxazolyl) thiophene, 2,2 '-(p-phenylenedivinylene) -bisbenzothiazole , 4, 4'-
Bis (2-benzoxazolyl) biphenyl, 2,5-bis [5- (α, α-dimethylbenzyl) -2-benzoxazolyl] thiophene, 4,4′-bis [5,7-di- (2- Methyl-2-butyl) -2-benzoxazoyl] stilbene, 2,5-bis [5,7-di- (2-methyl-2-butyl) -2-benzoxazoyl] -3,4
-Diphenylthiophene, 2- {2- [4- (2-benzimidazolyl) phenyl] vinyl} benzimidazole, 5-methyl-2- {2- [4- (5-methyl-2-)
Benzoxazolyl) phenyl] vinyl} benzoxazole, 2,5-bis (5-methyl-2-benzoxazolyl) thiophene, 2- [2- (4-carboxyphenyl) vinyl] benzimidazole, 2- [2- (4- (Chlorophenyl) vinylnaphtho [1,2-d] oxazole, a metal complex of 8-hydroxyquinoline and a derivative thereof described in JP-A-63-295695.
And Applied Physics, 61, 1044 (1992) and Japanese Patent Laid-Open No.
Examples thereof include oxadiazole-based compounds described in JP-A-363894.

Next, an organic thin film E using the compound of the present invention
An example of a suitable method for producing an L element will be described for each element of each configuration. The method for producing the organic thin film EL device composed of the above-mentioned anode / light emitting layer / cathode will be described. First, a thin film of a desired electrode substance, for example, a substance for anode, is formed on a suitable substrate at 1 μm or less, preferably 10 to 200 n.
After forming the anode by a method such as vapor deposition or sputtering so that the film thickness is within the range of m, and then forming a thin film of the compound represented by the general formula (1), which is a light emitting material, on the anode. A light emitting layer is provided. Examples of methods for thinning the light emitting material include a spin coating method, a casting method, and a vapor deposition method, which will be described below.

When a vapor deposition method is used for thinning the light emitting material, the vapor deposition conditions vary depending on the type of organic compound used in the light emitting layer to be used, the target crystal structure of the molecular cumulative film, the association structure and the like. , Generally boat heating temperature 50-4
00 ° C, vacuum degree 10 ^-5 to 10 ^-2 Pa, vapor deposition rate 0.0
It is desirable to appropriately select in the range of 1 to 50 nm / sec, substrate temperature of -50 to + 300 ° C., and film thickness of 5 nm to 5 μm.

When the mixture of the light emitting material and the organic charge injecting and transporting material is formed into a thin film by the vapor deposition method, generally, the co-evaporation method can be used, and the light emitting material and the organic charge injecting and transporting material are provided in different boats. Then, each boat is heated and vapor-deposited to form a thin film of the mixture. The vapor deposition conditions in that case are the same as the above-mentioned conditions, and the mixture ratio of the mixture can be adjusted by controlling the vapor deposition rate of each compound by the heating temperature of each boat.

Further, when the spin coating method is adopted,
The conditions vary depending on the type of material used, the type of solvent, etc., but generally a solution concentration of 0.001 to 90 parts by weight,
Spinner rotation speed 100 to 100,000 rotations / minute, substrate temperature -50 to 300 ° C., film thickness of 5 n depending on these conditions
It is desirable to adjust the thickness to be in the range of m to 5 μm. Furthermore, after spin coating, it is desirable to perform heat treatment at 30 to 400 ° C. for 10 minutes to 24 hours in an atmosphere of an inert gas such as nitrogen or argon.

Next, after forming this light emitting layer, a thin film of a substance for a cathode is formed thereon by a method of 1 μm or less, for example, vapor deposition or sputtering, and a cathode is provided to obtain a desired organic thin film EL element. can get. In the production of this organic thin film EL element, it is possible to reverse the production order and produce the cathode, the light emitting layer and the anode in this order.

Next, a method of manufacturing an organic thin film EL element consisting of anode / hole injecting / transporting layer / light emitting layer / cathode will be described. First, after forming an anode in the same manner as in the case of the organic thin film EL element described above. A thin film made of a hole transfer compound is formed thereon by a vapor deposition method, a spin coating method, or the like to provide a hole injecting and transporting layer. The conditions at this time may be the same as the conditions for forming the thin film of the light emitting material. Next, a light emitting layer and a cathode are sequentially formed on the hole injecting and transporting layer, and the organic thin film EL is formed.
A desired organic thin film EL element can be obtained by providing the same as in the case of manufacturing the element. In addition, this organic thin film E
Also in the production of the L element, the production order is reversed and the cathode,
It is also possible to fabricate the light emitting layer, the hole injecting and transporting layer, and the anode in this order.

A method of manufacturing an organic thin film EL element composed of anode / light emitting layer / electron injecting / transporting layer / cathode will be described. First, an anode is formed in the same manner as in the case of the organic thin film EL element, and then the organic thin film EL element is formed. A thin film made of a light emitting material is formed on the above and a light emitting layer is provided. Next, a thin film made of an electron transfer compound is vapor-deposited on the light emitting layer,
A desired organic thin film EL element is obtained by forming the layer by means of spin coating or the like, providing an electron injecting and transporting layer, and then providing a cathode thereon in the same manner as in the case of manufacturing the organic thin film EL element. Also in the production of this organic thin film EL element, it is possible to reverse the production order and produce the cathode, the electron injecting and transporting layer, the light emitting layer and the anode in this order.

Further, anode / hole injecting / transporting layer / light emitting layer /
Explaining a method of manufacturing an organic thin film EL element composed of an electron injecting / transporting layer / cathode, an anode, a hole injecting / transporting layer, a light emitting layer, an electron injecting / transporting layer, and a cathode are formed in the same manner as in the organic thin film EL element. A desired organic thin film EL element can be obtained by sequentially providing. Also in the production of this organic thin film EL element, it is possible to reverse the production order to produce the cathode, the light emitting layer, the hole injecting and transporting layer and the anode in this order.

When a DC voltage is applied to the thus obtained organic thin film EL element, the anode is + and the cathode is −.
When a voltage of about 2 to 40 V is applied as the polarity of, the emission can be observed from the transparent or semitransparent electrode side. Moreover, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Further, when an AC voltage is applied, light is emitted only when the anode is in the + state and the cathode is in the − state. The waveform of the alternating current applied may be arbitrary.

Next, the light emitting mechanism of the organic thin film EL device will be described by taking the case of the structure of anode / hole injecting / transporting layer / light emitting layer / cathode as an example. When a voltage is applied with the positive polarity of the anode and the negative polarity of the cathode, electric field is injected from the anode into the hole injecting and transporting layer. The injected holes are transported inside the hole injecting and transporting layer toward the interface with the light emitting layer, and are injected or transported from the interface to a region where a light emitting function is exhibited (for example, the light emitting layer).

On the other hand, the electrons are injected from the cathode into the light emitting layer by an electric field, further transported, and recombined with the holes in the region where the holes are present, that is, the region where the light emitting function is exhibited (in this sense, The region may be called a recombination region). When this recombination occurs, an excited state of a molecule, its associated body, a crystal, or the like is formed, and this is converted into light. The recombination region may be at the interface between the hole injecting and transporting layer and the light emitting layer, at the interface between the light emitting layer and the cathode, or at the center of the light emitting layer distant from both interfaces. This depends on the type of compound used, its association and crystal structure.

[0043]

EXAMPLES The present invention will be described in more detail based on examples.

Example 1 IT was placed on a glass substrate of 25 mm × 75 mm × 1.1 mm.
A film in which O was formed into a film having a thickness of 180 nm by a sputtering deposition method (manufactured by Tokyo Sanyo Vacuum Co., Ltd.) was used as a transparent support substrate. This transparent support substrate was fixed to a substrate holder of a commercially available vapor deposition device (manufactured by Vacuum Kiko Co., Ltd.), and N, N′-diphenyl-N, N′-bis- (3-methylphenyl) -4,
4'-diamine is vapor-deposited from a quartz crucible on a transparent supporting substrate at a vacuum degree of 8 x 10 ^-4 Pa at a vapor deposition rate of 0.1 to 0.2 nm / sec to form a hole injecting and transporting layer having a thickness of 50 nm. The film was formed. Subsequently, the compound represented by the formula (4) was vapor-deposited at a rate of 0.005 from a quartz crucible at a vacuum degree of 8 × 10 ⁻⁴ Pa.
.About.0.007 nm / sec and tris (8-hydroxyquinolino) aluminum from a quartz crucible from 0.3 to 0.
A light emitting layer having a film thickness of 50 nm was formed on the hole injecting and transporting layer by a co-evaporation method at 4 nm / sec. Then, as a cathode electrode, a vacuum deposition rate of 1 × 10 ⁻³ Pa was used to deposit magnesium from the graphite crucible at a deposition rate of 1 to 1.2 nm / sec, and silver was deposited from the graphite crucible at a deposition rate of 0.08 to
0.25c through a shadow mask at 0.11 nm / sec
It was prepared by co-evaporating a magnesium-silver electrode with an area of m ² to a thickness of 150 nm. When a direct current voltage was applied to the device thus prepared with the ITO electrode as the anode and the magnesium-silver electrode as the cathode, a stable reddish orange light emission was obtained in the atmosphere. Its brightness is 3 at 7V
It was 50 cd / m ² .

Example 2 After forming the hole injecting and transporting layer of Example 1, the compound represented by the formula (4) was formed on the hole injecting and transporting layer at a vacuum degree of 8 × 10 ⁻⁴ Pa from a quartz crucible. Deposition rate 0.005-0.008n
Deposition rate of quinacridone from a quartz crucible at a rate of 0.
002 to 0.004 nm / sec, and tris (8-hydroxyquinolino) aluminum from a quartz crucible at a deposition rate of 0.3 to 0.4 nm / sec by a co-evaporation method to a film thickness of 50 nm.
The light emitting layer of was formed into a film. Then, a magnesium-silver cathode electrode was formed thereon in the same manner as in Example 1. When a DC voltage was applied to the device thus produced in the same manner as in Example 1, reddish orange light emission was obtained. Its brightness is 7V
Was 520 cd / m ² .

Example 3 A device was prepared in the same manner as in Example 1 except that the compound represented by the formula (4) in Example 1 was replaced by the compound represented by the formula (5). When a DC voltage was applied to the element thus produced in the same manner as in Example 1, red light emission was obtained. Its brightness is 7
It was 140 cd / m ² at V.

Example 4 0.3 parts by weight of polyvinylcarbazole was dissolved in 1,2-dichloroethane as a hole injecting and transporting layer on the transparent supporting substrate of Example 1, and a film having a thickness of 30 nm was formed by spin coating. It was fixed to the substrate holder of the vapor deposition device. Next, the compound represented by the formula (4) was evaporated from a quartz crucible at a vacuum degree of 8 × 10 ⁻⁴ Pa from a quartz crucible at a deposition rate of 0.005 to 0.008 nm / sec and 2,5-bis (5′-tachary butyl-). A light-emitting layer having a film thickness of 50 nm was formed by a co-evaporation method of 2-benzoxazoyl) thiophene from a crucible made of quartz at a deposition rate of 0.3 to 0.4 nm / sec. Then, a magnesium-silver cathode electrode was formed thereon similarly to the example. When a DC voltage was applied to the thus-produced element in the same manner as in Example 1, orange light emission was obtained. The brightness was 300 cd / m ² at 7V.

Example 5 After the light emitting layer of Example 4 was prepared, tris (8-hydroxyquinolino) aluminum was used as an electron injecting and transporting layer on the light emitting layer at a vacuum degree of 8 × 10 ⁻⁴ Pa and a deposition rate of 0.3 to 0. 0.5 nm /
A 20 nm film was formed in seconds. Then, a magnesium-silver cathode electrode was formed thereon in the same manner as in Example 1. When a DC voltage was applied to the thus-produced element in the same manner as in Example 1, orange light emission was obtained. The brightness was 330 cd / m ² at 7V.

EXAMPLE 6 0.5 parts by weight of polyvinylcarbazole and 0.5 of 2,5-bis (1-naphthyl) -1,3,4-oxadiazole were used as a light emitting layer on the transparent supporting substrate of Example 1. Parts by weight,
And 0.02 part by weight of the compound represented by the formula (4)
Dissolve in 2-dichloroethane and spin coat to 1
The film was formed to a thickness of 00 nm and fixed to the substrate holder of the vapor deposition device. Then, a magnesium-silver cathode electrode was formed thereon in the same manner as in Example 1. When a DC voltage was applied to the thus-produced element in the same manner as in Example 1, orange light emission was obtained. Its brightness is 260 cd at 7V
/ M ² .

Example 7 After forming the light emitting layer of Example 6, the transparent supporting substrate was fixed to the substrate holder of the vapor deposition apparatus. Subsequently, tris (8-hydroxyquinolino) aluminum was used as an electron injecting and transporting layer on the light emitting layer at a vacuum degree of 8 × 10 ⁻⁴ Pa and a deposition rate of 0.3 to 0.
It was vapor-deposited at a thickness of 20 nm at 5 nm / sec. Then, a magnesium-silver cathode electrode was formed on the electron injecting and transporting layer in the same manner as in Example 1. When a DC voltage was applied to the thus-produced element in the same manner as in Example 1, orange light emission was obtained. The brightness was 300 cd / m ² at 7V.

EXAMPLE 8 0.5 parts by weight of polyvinylcarbazole, bis (1-naphthyl) -1,
0.5 parts by weight of 3,4-oxadiazole, 1,2,
4,5,3H, 6H, 10H-Tetrahydro-8-trifluoromethyl [1] benzopyrano (9,9a, 1-g
h) 0.01 parts by weight of quinolidin-10-one and 0.02 parts by weight of the compound represented by the formula (4) were dissolved in 1,2-dichloroethane, and 100 n was prepared by spin coating.
The film was formed to a thickness of m and fixed to the substrate holder of the vapor deposition device. Then, on top of that, magnesium as in Example 1
A silver cathode electrode was created. When a DC voltage was applied to the thus-produced element in the same manner as in Example 1, orange light emission was obtained. Its brightness is 310 cd / at 7V.
It was m ² .

Comparative Example 1 The compound of the formula (4) was prepared in the same manner as in Example 1.
A device was prepared in the same manner as in Example 1 except that (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran was used instead. When a DC voltage was applied to the thus-produced device in the same manner as in Example 1, orange light emission due to 4- (dicyanomethylene) -2-methyl-6- (p-dimethylaminostyryl) -4H-pyran was obtained. However, after a while, the color changed to yellowish green emission due to tris (8-hydroxyquinolino) aluminum.

[0053]

As described above, the organic thin film E of the present invention is
Since the L element enables highly efficient emission of light having a wavelength longer than yellow, which has been difficult in the past, it is extremely useful as a flat light source or a light emitting element for a display, and its industrial value is high.

Claims (3)

[Claims] 1. An organic thin film EL element in which an organic thin film is supported between a pair of electrodes, at least one of which is transparent,
General formula (1) An organic thin-film EL device comprising at least one compound represented by (In the general formula (1),
R1 and R2 are each independently hydrogen, fluorine, chlorine, cyano group, carboxyl group, acyl group, alkyl group, fluoroalkyl group, aryl group, alkyloxycarbonyl group, benzimidazolyl group, benzoxazolyl group, or benzthiazolyl group. And R1 and R2 may combine with each other to form a saturated or unsaturated five-membered ring or six-membered ring. R3 and R4 are each independently hydrogen or an alkyl group, and R3 and R4 may be bonded to each other to form an unsaturated 6-membered ring. R5 is a hydroxyl group, an alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an acylamino group, a pyrazolyl group, a triazolyl group,
Or a morpholino group, R6 is hydrogen, the amino nitrogen of R5 may be bonded to R4 to form a pyrrolidine ring or a piperidine ring, or the amino nitrogen of R5 may be bonded to R4 and R6 to form a julolidine ring. May form a ring). 2. A light emitting layer is provided between a pair of electrodes, at least one of which is transparent, and each layer is composed of at least one charge injecting and transporting layer such as a hole injecting and transporting layer and an electron injecting and transporting layer. In the organic thin film EL device, the general formula (1): An organic thin-film EL device comprising at least one compound represented by (In the general formula (1),
R1 and R2 are each independently hydrogen, fluorine, chlorine, cyano group, carboxyl group, acyl group, alkyl group, fluoroalkyl group, aryl group, alkyloxycarbonyl group, benzimidazolyl group, benzoxazolyl group, or benzthiazolyl group. And R1 and R2 may combine with each other to form a saturated or unsaturated five-membered ring or six-membered ring. R3 and R4 are each independently hydrogen or an alkyl group, and R3 and R4 may be bonded to each other to form an unsaturated 6-membered ring. R5 is a hydroxyl group, an alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an acylamino group, a pyrazolyl group, a triazolyl group,
Or a morpholino group, R6 is hydrogen, the amino nitrogen of R5 may be bonded to R4 to form a pyrrolidine ring or a piperidine ring, or the amino nitrogen of R5 may be bonded to R4 and R6 to form a julolidine ring. May form a ring). 3. A compound represented by the general formula (1): The compound represented by the general formula (2): The organic thin film EL device according to claim 1 or 2, which is a compound represented by the formula (1). (General formula (1)
In and (2), R1 and R2 are each independently hydrogen, fluorine, chlorine, cyano group, carboxyl group, acyl group, alkyl group, fluoroalkyl group, aryl group, alkyloxycarbonyl group, benzimidazolyl group, benzoxazoli R1 and R2 may be bonded to each other to form a saturated or unsaturated five-membered ring or six-membered ring. R3 and R4 are each independently hydrogen or an alkyl group, and R3 and R4 may be bonded to each other to form an unsaturated 6-membered ring. R5
Is a hydroxyl group, an alkoxy group, an amino group, an alkylamino group, a dialkylamino group, an acylamino group, a pyrazolyl group, a triazolyl group, or a morpholino group, and R6
Is hydrogen, and the amino nitrogen of R5 may combine with R4 to form a pyrrolidine ring or a piperidine ring,
Alternatively, the amino nitrogen of R5 may combine with R4 and R6 to form a julolidine ring. L1 to L3 are each independently hydrogen or an alkyl group having 1 to 6 carbon atoms, L4 is hydrogen, and L1 and L2 and L3 and L4 are bonded to each other and include a nitrogen atom adjacent to L2 and L3. May form a six-membered ring).