JP2003243175A - Organic electroluminescent element and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a high-brightness and long-life organic electroluminescent element and a high-brightness and long-life display device using the organic electroluminescent element. <P>SOLUTION: The organic electroluminescent element contains a cyclodextrin class or a cyclodextrin derivative. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an organic electroluminescence (hereinafter abbreviated as organic EL) element and a display device. More specifically, the present invention relates to an organic electroluminescent element having excellent emission brightness and long life, and a display device having the organic electroluminescent element.

[0002]

2. Description of the Related Art An electroluminescent display (ELD) is used as a light emitting type electronic display device.
There is. Examples of the ELD constituent elements include an inorganic electroluminescent element and an organic electroluminescent element. Inorganic electroluminescent elements have been used as a flat light source, but a high alternating voltage is required to drive the light emitting element. An organic electroluminescence device has a structure in which a light emitting layer containing a compound that emits light is sandwiched between a cathode and an anode, and electrons and holes are injected into the light emitting layer to recombine to generate excitons (excitons). It is an element that emits light by utilizing the emission of light (fluorescence / phosphorescence) when the excitons are generated and deactivated, and can emit light at a voltage of several V to several tens of V. Further, it is a self-luminous type. Therefore, it has a wide viewing angle and high visibility, and since it is a thin-film type complete solid-state element, it is attracting attention from the viewpoints of space saving, portability, and the like.

However, in the organic EL element for practical use in the future, it is desired to develop an organic EL element which emits light with high efficiency and low power consumption.

All the molecules used as dopants in organic EL devices have high fluorescence quantum yields.
Since it is easy to form exciplex, it cannot be used as a host compound for light emission.

On the other hand, when light emission from excited singlet is used in an organic EL, the generation ratio of singlet excitons and triplet excitons is 1: 3, so that the generation probability of luminescent excited species is 25.
% And the light extraction efficiency is about 20%, the external extraction quantum efficiency (ηext) is limited to 5%. However, since Princeton University reported an organic EL device using phosphorescence emission from excited triplet (MA Baldo et al., Nature, 3
95, 151-154 (1998), active research on materials that exhibit phosphorescence at room temperature (eg, MA Baldo et al., Nature).
e, vol. 403, issue 17, pages 750-753 (200
0), US Pat. No. 6,097,147, etc.). When the excited triplet is used, the upper limit of the internal quantum efficiency becomes 100%, so that in principle, the luminous efficiency is four times higher than that of the excited singlet, and the performance is almost the same as that of a cold cathode tube. It can be applied to and attracts attention.

[0006]

SUMMARY OF THE INVENTION An object of the present invention is to provide an organic electroluminescence device having high brightness and long life, and a display device having high brightness and long life using the organic electroluminescence device of the present invention. is there.

[0007]

The above objects of the present invention have been achieved by the following constitutions.

1. An organic electroluminescence device comprising a cyclodextrin.

2. An organic electroluminescence device comprising a cyclodextrin derivative.

3. An organic electroluminescence device comprising an inclusion complex of an organic compound and cyclodextrins.

4. An organic electroluminescence device comprising an inclusion complex of an organic compound and a cyclodextrin derivative.

5. 5. The organic electroluminescence device according to 2 or 4 above, wherein the cyclodextrin derivative has a hole transporting ability or an electron transporting ability.

6. 6. The organic electroluminescent device according to the above 2, 4 or 5, wherein the cyclodextrin derivative has triarylamine as a partial structure.

7. 7. The organic electroluminescence device according to any one of 3 to 6, wherein the organic compound is an aromatic hydrocarbon or a derivative thereof.

8. 8. The organic electroluminescence device according to any one of 1 to 7 above, wherein the cyclodextrin and the cyclodextrin derivative are β-cyclodextrin.

9. 9. The organic electroluminescence device according to any one of 1 to 8 above, wherein at least one molecular structure of cyclodextrin, a cyclodextrin derivative, and an organic compound is halogen-substituted.

10. 10. The organic electroluminescence device according to any one of 1 to 9 above, which contains at least one of iridium, platinum, and an osmium complex.

11. Any one of the above 1 to 10, wherein the layer containing the compound is a layer formed by applying the coating solution by acting in a solution to form a coating solution.
An organic electroluminescence device according to the item 1.

12. A display device comprising the organic electroluminescence element according to any one of 1 to 11 above.

The present invention will be described in more detail. For cyclodextrins and cyclodextrin derivatives,
"Cyclodextrin: Fundamentals and Applications" (edited by Akihiko Ueno,
Details on Industrial Books, 1995).

Among organic EL light-emitting materials, some molecules having high planarity have a high fluorescence quantum yield but are easily made into exciplexes. These compounds could only be used as so-called dopants that emit light by energy transfer from the host compound. However, as in the present invention, by encapsulating these compounds in a cyclodextrin or a cyclodextrin derivative, an exciplex is not formed, so that the compound can be used as a host compound and can contribute to the improvement of luminous efficiency. . Also,
Such an inclusion complex also has improved thermal stability and can contribute to prolonging the life of the organic EL device.

Further, when the partial structure of the cyclodextrin derivative has a hole transporting ability or an electron transporting ability, the inclusion complex becomes a functional molecule having both carrier transport and light emission, and therefore the device structure Can be further simplified,
It has an advantage that the device can be easily manufactured.

On the other hand, phosphorescence was usually considered to be observable only at a low temperature of 77 K, but since the discovery of compounds capable of observing phosphorescence at room temperature in recent years, many compounds have been found to be heavy metal complexes such as iridium complexes. Has been studied mainly for synthesis (for example, S. Lamansky et al.,
J. Am. Chem. Soc. , 123, 4304, 2001). In addition, R. A. Famia et al., Hamai's report (eg, J. Phys. Chem. 89th.
Vol., 1897 (1985), Bull. Che
m. Soc. Volume 71, page 1549 (1998)
Et al.), Phosphorescence emission at room temperature was observed for the inclusion complexes of cyclodextrins and cyclodextrin derivatives. Utilizing this phosphorescence can contribute to the improvement of luminous efficiency.

Specific examples of the cyclodextrins and cyclodextrin derivatives of the present invention include cyclic compounds composed of a plurality of glucoses represented by the following general formula (A).

[0025]

[Chemical 1]

In the general formula (A), R represents an OH group in the case of cyclodextrins, and R represents a group in which the OH group is chemically modified in the case of a cyclodextrin derivative.
n represents an integer of 3 or more. Preferably, n is 6 or more and 12
It is the following.

In the present invention, cyclodextrins are
It is a compound in which 3 or more and 12 or less glucose, preferably 6 to 8 glucose are cyclically bonded, and is a non-induced compound that is not chemically modified. The cyclodextrins used in the present invention may be those capable of including an organic compound, for example, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin (6, 7 and 8 glucose rings, respectively). Or one or two or more of those bonded to) are used, and those capable of obtaining an inclusion complex with an organic compound in a solution are preferably selected.

In the present invention, the cyclodextrin derivative is a compound represented by the general formula (A) in which chemically modified R is specifically hydroxyalkylated cyclodextrin, alkylated cyclodextrin or glycosylated cyclodextrin. Dextrins, aminated cyclodextrins, amidated cyclodextrins, hydroxyarylated cyclodextrins, arylated cyclodextrins, sulfonylated cyclodextrins, acylated cyclodextrins, carboxymethylated cyclodextrins, etc. At least part of it is hydroxyethyl, 2-hydroxypropyl, 2,3-
Cyclodextrin derivatives chemically modified with hydrophilic functional groups such as dihydroxypropyl, 2-hydroxybutyl, 2-hydroxyisobutyl, diethylaminoethyl, and trimethylammoniopropyl, and polymerized with crosslinking agents such as epichlorohydrin and polyvalent glycidyl ether Examples of the cyclodextrin polymers include branched cyclodextrins having branched side chains such as glucose and maltose.

The cyclodextrin derivative is preferably substituted with a compound having a partial structure having a hole transporting ability or an electron transporting ability as shown below. More preferably, triarylamine has a partial structure.

[0030]

[Chemical 2]

[0031]

[Chemical 3]

In the formula, L ₁ , L ₂ , L ₃ , L ₄ , L ₅ and L ₆ represent a linking group. Specific examples of the linking group represented by L ₁ , L ₂ , L ₃ , L ₄ , L ₅ , and L ₆ include, but are not limited to, those represented by (1) to (14). At this time,*
Represents a binding site to the 6th carbon atom. A linking group may be further introduced between the carbon atom at * and the 6-position, and specific examples thereof include an alkyl group.

[0033]

[Chemical 4]

[0034]

[Chemical 5]

Although an example of β-cyclodextrin is shown here, α, γ-cyclodextrin, or α, γ-cyclodextrin
The same applies to β, γ-cyclodextrin derivatives. Also, regarding the connecting site, it is shown that it is connected at the 6th position.
They may be connected in different positions.

Among the cyclodextrins and cyclodextrin derivatives of the present invention, β-cyclodextrin or its derivative is preferable. Further, preferably,
A part of the molecular structure of the cyclodextrin and the cyclodextrin derivative is halogen-substituted.

Concretely, when L ₂ is (2), 4.0 g of dry β-cyclodextrin showing a synthesis example and 1.5 g of the following compound (1-1) are dissolved in 100 ml of anhydrous pyridine, and nitrogen is added. The mixture was heated and stirred under an atmosphere at 60 ° C. After 10 minutes, an insoluble matter was deposited, so that the reaction solution was returned to room temperature after 1 hour, and pyridine was completely distilled off by concentration under reduced pressure. The obtained oily substance was dissolved in a small amount of water and purified by column chromatography to obtain 0.68 g of the desired product.

[0038]

[Chemical 6]

Cyclodextrins and cyclodextrin derivatives have a function of adsorbing an organic compound in the pores and clathrating them. In the present invention, the compound (guest) included in the cyclodextrin (host) is an organic compound.

In the present invention, any one kind or two or more kinds of the inclusion complex by the cyclodextrin and the inclusion complex by the cyclodextrin derivative is used.

Specifically, the method of encapsulating the organic compound may be carried out at any temperature by adding and mixing the organic compound (guest) to the cyclodextrin or cyclodextrin derivative (host) solution, but preferably 20 ~
Stir mix at 60 ° C. For inclusion, even if cyclodextrins and cyclodextrin derivatives are not dissolved,
It can be achieved by mixing and stirring with an organic compound for a long time,
When the cyclodextrins and the cyclodextrin derivative are completely dissolved, the inclusion can be achieved most efficiently and efficiently.

For stirring, a propeller type agitator, a homomixer, a kneader, an automatic mortar or the like can be used. Stirring conditions differ depending on the type of stirring equipment used, the concentration of cyclodextrin and cyclodextrin derivative solution used, and the temperature, and preferably 50 to 1
It is convenient to choose conditions that result in a uniform emulsion or clear solution at 0000 rpm.

The inclusion reaction time is 0.25 to 24 hours, and when it is desired to complete the inclusion in a short time, 1,000 to 16, using a homomixer having strong shearing force and stirring force,
If the inclusion may take a long time at 0.25 rpm for 0.25 to 8 hours, use an agitator or kneader with a weak shearing force or stirring force at 50 to 1,000 rpm for 2 hours.
The conditions suitable for the characteristics of the raw materials used, the solution viscosity at the time of inclusion, and the ability of the stirrer can be selected in the range of -24 hours.

In the organic EL device of the present invention, any organic compound can be used as the organic compound to be included in the cyclodextrin or the cyclodextrin derivative. A preferable organic compound is a fluorescent organic compound having a high fluorescence quantum yield in a solution state. Here, the fluorescence quantum yield is preferably 10% or more, and particularly preferably 30% or more. Aromatic hydrocarbons and their derivatives are also preferable.

Fluorescent organic molecules having a high fluorescence quantum yield as guests include, for example, coumarin dyes, pyran dyes, cyanine dyes, croconium dyes, squalium dyes, oxobenzanthracene dyes, fluorescein dyes, rhodamine dyes. Examples thereof include dyes, pyrylium dyes, perylene dyes, stilbene dyes, and polythiophene dyes.

As the aromatic hydrocarbon and its derivative, naphthalene, 1-cyanonaphthalene, 2-methylnaphthalene, 2-chloronaphthalene, anthracene,
Decacyclene, fluoranthene, diphenylbenzofluoranthene, pentacene, hexacene, acenaphthene,
Pyrene, sodium pyrene sulfonate, acenaphthene,
There are azulene, perylene, 6-bromo-2-naphthol, chlorophenol, diphenyl phosphate, rubrene, chrysene, triphenylene, coronene, quinacridone, and derivatives thereof. These compounds may be further substituted with substituents, preferably halogen substitution products.

When two different molecules enter into the narrow hole of cyclodextrin, the force acting between the two molecules becomes stronger than when they freely move in a wide space. Normal,
One molecule of the compound enters into the hole of one molecule of cyclodextrin, but this 2: 1 inclusion complex of the 1: 1 inclusion complex itself (two molecules of cyclodextrin are attached, It has two molecules of other compounds inside).

The inclusion phenomenon of cyclodextrin in solution can be investigated mainly spectroscopically. For example, absorption spectrum, fluorescence spectrum, phosphorescence spectrum, NMR
It can be investigated by a spectrum, a CD spectrum, or the like.

The organic EL device of the present invention may contain a complex compound in which the central metal is osmium, iridium or platinum. These compounds are phosphorescent compounds, the cyclodextrin of the present invention, or
When it functions as a dopant when the inclusion complex of a cyclodextrin derivative and an organic compound is used as a host, it is considered that it can contribute most to the improvement of the luminous efficiency of the organic EL device. Specific examples of the complex-type compound in which the central metal used in the present invention is osmium, iridium, or platinum are shown below, but the invention is not limited thereto.

[0050]

[Chemical 7]

[0051]

[Chemical 8]

[0052]

[Chemical 9]

On the other hand, in the organic EL device of the present invention, it is desirable to manufacture the device by a coating method in which the light emitting layer is made to act in a solution to form a coating solution, and the layer is formed by applying this coating solution.

The organic EL device of the present invention has a hole injecting layer, a hole transporting layer, an electron injecting layer, an electron transporting layer, an anode buffer layer and a cathode buffer layer in addition to the light emitting layer, if necessary. It has a structure sandwiched between a cathode and an anode.

Specifically, (i) anode / light emitting layer / cathode (ii) anode / hole transport layer / light emitting layer / cathode (iii) anode / light emitting layer / electron transport layer / cathode (iv) anode / positive Hole transport layer / light emitting layer / electron transport layer / cathode (v) anode / anode buffer layer / hole transport layer / light emitting layer /
There are structures such as electron transport layer / cathode buffer layer / cathode.

The compound of the present invention may be contained in any layer, but is preferably contained in the light emitting layer.

The light emitting layer is a layer that emits light by recombination of electrons and holes injected from the electrode or the electron injection layer, the electron transport layer, the hole injection layer, and the hole transport layer. May be inside the light emitting layer or at the interface between the light emitting layer and the adjacent layer.

The light emitting material may have a hole injecting ability, a hole transporting function, an electron injecting ability, and an electron transporting function in addition to the light emitting ability. Most of the electron transport materials can also be used as the light emitting material.

The light emitting layer can be formed by a known thin film forming method such as a vacuum vapor deposition method, a spin coating method, a casting method, a dip coating method, an LB method and an ink jet method. Preferred are a spin coating method, a casting method and a dip coating method. The thickness of the light emitting layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The light emitting layer may have a single layer structure composed of one or more kinds of these light emitting materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions.

Further, this light emitting layer is disclosed in JP-A-57-517.
As described in Japanese Patent Publication No. 81-81, after the light emitting material is dissolved in a solvent together with a binder such as a resin to form a solution,
This can be formed into a thin film by a spin coating method or the like. The thickness of the light emitting layer thus formed is not particularly limited and may be appropriately selected depending on the situation, but is usually in the range of 5 nm to 5 μm.

Next, the hole injection layer, the hole transport layer, the electron injection layer, and the electron transport layer will be described.

The hole injection layer and the hole transport layer have a function of transmitting the holes injected from the anode to the light emitting layer. The hole injection layer and the hole transport layer are provided between the anode and the light emitting layer. By interposing, many holes are injected into the light emitting layer at a lower electric field, and further, the electrons injected from the cathode, the cathode buffer layer or the electron injection layer, and the electron transport layer into the light emitting layer are Due to the barrier of electrons existing at the interface between the injection layer and the hole transport layer, the device is excellent in light emission performance such as being accumulated at the interface in the light emitting layer and improving the light emission efficiency. The material of the hole injection layer and the hole transport layer (hereinafter referred to as the hole injection material and the hole transport material) is not particularly limited as long as it has the above-mentioned preferable properties, and conventionally, in the optical transmission material. Any material can be selected and used from the materials commonly used as a hole charge injecting and transporting material and the known materials used for the hole injecting layer and the hole transporting layer of EL elements.

The hole injecting material and hole transporting material have any of hole injecting or transporting property and electron barrier property, and may be either organic or inorganic.
Examples of the hole injection material and the hole transport material include carbazole derivatives, triazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives and pyrazolone derivatives, aromatic tertiary amine compounds (for example, 4 , 4'-bis [N-
(1-naphthyl) -N-phenylamino] biphenyl (NPD), 4,4 ′, 4 ″ -tris [N-, in which three triphenylamine units are linked in a starburst type
(3-methylphenyl) -N-phenylamino] triphenylamine (MTDATA) etc.), phenylenediamine derivative, arylamine derivative, porphyrin compound, amino-substituted chalcone derivative, oxazole derivative,
Styrylanthracene derivative, fluorenone derivative, hydrazone derivative, stilbene derivative, silazane derivative,
Examples thereof include aniline-based copolymers, polysilane-based compounds, polythiophenes, poly (N-vinylcarbazole) derivatives, and conductive polymer oligomers such as (substituted) polythiophene-polystyrene sulfonic acid mixtures, particularly thiophene oligomers. As the hole injecting material and the hole transporting material, the above materials can be used, but it is particularly preferable to use a conductive polymer oligomer such as a (substituted) polythiophene-polystyrene sulfonic acid mixture.

Further, it is also possible to use a polymer material in which these materials are introduced into the polymer chain, or where these materials are used as a polymer main chain.

Inorganic compounds such as p-type-Si and p-type-SiC can also be used as the hole injecting material and the hole transporting material. The hole injecting layer and the hole transporting layer are formed by using the above hole injecting material and the hole transporting material by a known method such as a vacuum deposition method, a spin coating method, a casting method, a dip coating method, and an inkjet method LB method. Can be formed by thinning. The thickness of the hole injection layer and the hole transport layer is not particularly limited, but usually 5 nm to
It is about 5 μm. The hole injection layer and the hole transport layer may have a single layer structure composed of one or more of the above materials, or may have a laminated structure composed of a plurality of layers having the same composition or different compositions. Further, the electron injection layer and the electron transport layer, which are used as necessary, may have a function of transmitting the electrons injected from the cathode to the light emitting layer, and the material thereof is any of the conventionally known compounds. Those selected can be used.

Examples of materials used for the electron injection layer and the electron transport layer (hereinafter referred to as electron injection materials and electron transport materials) include nitro-substituted fluorene derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives and naphthalene perylene. Heterocyclic tetracarboxylic acid anhydrides, carbodiimides, fluorenylidene methane derivatives, anthraquinodimethane and anthrone derivatives, oxadiazole derivatives, triazole derivatives, phenanthroline derivatives and the like. Further, in the oxadiazole derivative, a thiadiazole derivative in which an oxygen atom of the oxadiazole ring is substituted with a sulfur atom, and a quinoxaline derivative having a quinoxaline ring known as an electron-withdrawing group are also used as an electron injection material and an electron transport material. be able to.

Further, it is also possible to use a polymer material in which these materials are introduced into the polymer chain, or where these materials are used as a polymer main chain.

Also, metal complexes of 8-quinolinol derivatives, such as tris (8-quinolinol) aluminum (Alq), tris (5,7-dichloro-8-quinolinol) aluminum, tris (5,7-dibromo-8-).
Quinolinol) aluminum, tris (2-methyl-8)
-Quinolinol) aluminum, tris (5-methyl-)
8-quinolinol) aluminum, bis (8-quinolinol) zinc (Znq), etc., and the central metal of these metal complexes is In, Mg, Cu, Ca, Sn, Ga or Pb.
The metal complex replaced with can also be used as an electron injection material and an electron transport material. In addition, metal-free or metal phthalocyanine, or those whose terminal is substituted with an alkyl group, a sulfonic acid group, or the like can be preferably used as the electron injection material and the electron transport material. Further, the distyrylpyrazine derivative used as the material of the light emitting layer can also be used as the electron injecting material and the electron transporting material, and like the hole injecting layer and the hole transporting layer, n-type, Si and n-type- An inorganic semiconductor such as SiC can also be used as an electron injection material and an electron transport material.

The electron injecting layer and the electron transporting layer are formed by forming the above compound by a known thin film forming method such as a vacuum vapor deposition method, a spin coating method, a casting method, a dip coating method, an LB method and an ink jet method. Can be formed. The thickness of the electron injection layer and the electron transport layer is not particularly limited, but is usually selected in the range of 5 nm to 5 μm. The electron injection layer and the electron transport layer are made of these electron injection materials,
The electron transport material may have a single-layer structure composed of one or more kinds, or a laminated structure composed of a plurality of layers having the same composition or different compositions.

Further, a buffer layer (electrode interface layer) may be present between the anode and the light emitting layer or the hole injecting layer and between the cathode and the light emitting layer or the electron injecting layer.

The buffer layer is a layer provided between the electrode and the organic layer in order to reduce the driving voltage and improve the luminous efficiency.
Jan. 30, published by NTS Co., Ltd.), Volume 2, Chapter 2, "Electrode Materials" (Pages 123 to 166), and the anode buffer layer and the cathode buffer layer are described in detail. is there.

The anode buffer layer is described in JP-A-9-4547.
The details are also described in No. 9, No. 9-260062, No. 8-288069 and the like, and as a specific example, a phthalocyanine buffer layer represented by copper phthalocyanine,
Examples thereof include an oxide buffer layer typified by vanadium oxide, an amorphous carbon buffer layer, and a polymer buffer layer using a conductive polymer such as polyaniline (emeraldine) and polythiophene.

The cathode buffer layer is described in JP-A-6-3258.
No. 71, No. 9-17574, No. 10-74586, etc., the details are also described, and specifically, a metal buffer layer typified by strontium, aluminum, etc.,
Examples thereof include an alkali metal compound buffer layer typified by lithium fluoride, an alkaline earth metal compound buffer layer typified by magnesium fluoride, and an oxide buffer layer typified by aluminum oxide and lithium oxide.

Particularly, in the organic EL device of the present invention, when the cathode buffer layer was present, the driving voltage was lowered and the luminous efficiency was greatly improved.

The buffer layer is preferably a very thin film, and the film thickness is 0.1 to 10 depending on the material.
The range of 0 nm is preferred.

In addition to the above-mentioned basic constituent layers, layers having other functions may be laminated if necessary. For example, JP-A-11-204258, JP-A-11-204359, and "organic EL element and its industrialization". Frontline (1998 1
237 of January 30, issued by NTS Co., Ltd.)
It may have a functional layer such as a hole blocking (hole blocking) layer described on page.

Next, the electrodes of the organic EL element will be described. The electrodes of the organic EL element consist of a cathode and an anode.

As the anode in this organic EL device,
A material having a high work function (4 eV or more), an alloy, an electrically conductive compound or a mixture thereof as an electrode material is preferably used. Specific examples of such electrode substances include conductive transparent materials such as metals such as Au, CuI, indium tin oxide (ITO), SnO ₂ and ZnO.

For the above-mentioned anode, a thin film may be formed by a method such as vapor deposition or sputtering of these electrode substances, and a pattern having a desired shape may be formed by a photolithography method, or when pattern accuracy is not required so much. (About 100 μm or more), a pattern may be formed through a mask having a desired shape during vapor deposition or sputtering of the electrode material. When the emitted light is taken out from this anode, it is desirable that the transmittance is higher than 10%, and the sheet resistance as the anode is preferably several hundred Ω / □ or less. Further, the film thickness depends on the material, but is usually 10 nm to 1 μm.
m, preferably 10 nm to 200 nm.

On the other hand, as the cathode, a metal having a low work function (4 eV or less) (referred to as an electron injecting metal), an alloy, an electrically conductive compound, or a mixture thereof is used as an electrode material. Specific examples of such an electrode material include sodium, sodium / potassium alloy, magnesium, lithium, magnesium / copper mixture, magnesium / silver mixture, magnesium / aluminum mixture, magnesium / indium mixture, aluminum /
Aluminum oxide (Al ₂ O ₃ ) mixture, indium, lithium / aluminum mixture, rare earth metal and the like can be mentioned. Among these, from the viewpoint of electron injecting property and durability against oxidation, etc., a mixture of an electron injecting metal and a second metal which is a stable metal having a larger work function value, for example, a magnesium / silver mixture or magnesium. Aluminium / aluminum mixture, magnesium / indium mixture, aluminum / aluminum oxide (Al ₂ O ₃ ) mixture, lithium / aluminum mixture and the like are suitable.

Further, the cathode used in the organic EL device of the present invention is preferably an aluminum alloy, particularly preferably 90% by mass or more and less than 100% by mass, and most preferably 95% by mass or more and 100% by mass. Is less than. As a result, the light emission life of the organic EL element and the maximum attainable luminance can be greatly improved.

The cathode can be produced by forming a thin film of these electrode substances by a method such as vapor deposition or sputtering. The sheet resistance of the cathode is preferably several hundred Ω / □ or less, and the film thickness is usually 10
nm to 1 μm, preferably 50 to 200 nm. In order to transmit the emitted light, it is convenient that either the anode or the cathode of the organic EL element is transparent or semi-transparent and the luminous efficiency is improved.

The substrate preferably used for the organic EL device of the present invention is not particularly limited in the kind of glass, plastic, etc., and is not particularly limited as long as it is transparent.
Examples of the substrate preferably used for the electroluminescence element of the present invention include glass, quartz, and a light-transmissive plastic film.

As the light-transmissive plastic film,
For example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyether sulfone (PES), polyetherimide, polyether ether ketone, polyphenylene sulfide, polyarylate, polyimide, polycarbonate (PC), cellulose triacetate (TAC), cellulose Examples thereof include films made of acetate propionate (CAP) and the like.

Next, a suitable example for producing the organic EL device will be described. As an example, a method for producing an EL device composed of the above-mentioned anode / anode buffer layer / hole transport layer / light emitting layer / electron transport layer / cathode buffer layer / cathode will be explained.
First, a thin film of a desired electrode material, for example, a material for an anode, is formed on a suitable substrate to a thickness of 1 μm or less, preferably 10 to 20
The anode is formed by a method such as vapor deposition or sputtering so as to have a film thickness in the range of 0 nm. next,
A thin film made of the materials of the anode buffer layer, the hole transport layer, the light emitting layer, the electron transport layer, and the cathode buffer layer is formed thereon.

As a method for thinning the organic thin film layer,
As mentioned above, there are the spin coating method, the casting method, the dip coating method, the vapor deposition method, the ink jet method and the like, but the spin coating method is particularly preferable in that a uniform film is easily obtained and pinholes are hard to be generated. . Furthermore, a different film forming method may be applied for each layer. When the vapor deposition method is used for film formation, the vapor deposition conditions are the type of compound used,
Generally, the boat heating temperature is 50 to 450 ° C., the degree of vacuum is 10 ⁻⁶ to 10 ⁻² Pa, and the vapor deposition rate is 0.01 to 50 nm /
Second, substrate temperature is preferably -50 to 300 [deg.] C. and film thickness is 5 nm to 5 [mu] m.

After the formation of these layers, a thin film made of a material for the cathode is formed thereon to a thickness of 1 μm or less, preferably 50 to 200 n.
A desired EL element can be obtained by forming a film having a thickness in the range of m by a method such as vapor deposition or sputtering and providing a cathode. In the production of this organic EL element, it is preferable to consistently produce from the hole injecting layer to the cathode by one-time evacuation, but it is also possible to take out in the middle and apply a different film forming method. It is necessary to consider that the work should be performed in a dry inert gas atmosphere.

It is also possible to reverse the order of preparation so that the cathode, the cathode buffer layer, the electron transport layer, the light emitting layer, the hole transport layer, the anode buffer layer and the anode are fabricated in this order. When a direct current voltage is applied to the EL device thus obtained, the positive electrode has a positive polarity and the negative electrode has a negative polarity.
When about V is applied, light emission can be observed. Moreover, even if a voltage is applied with the opposite polarity, no current flows and no light emission occurs. Furthermore, when an AC voltage is applied, the anode is +,
It emits light only when the cathode is in the negative state. The waveform of the alternating current applied may be arbitrary.

The organic EL device of the present invention may be used as a kind of lamp for illumination or as an exposure light source, or may be a projection device of a type for projecting an image, or a type for directly visually recognizing a still image or a moving image. It may be used as a display device (display). When used as a display device for reproducing a moving image, either a simple matrix (passive matrix) method or an active matrix method may be used. In addition, a full-color display device can be manufactured by using two or more kinds of organic EL elements of the present invention having different emission colors.

[0090]

Example 1 After patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) on which ITO was deposited to a thickness of 150 nm as an anode, a transparent support substrate provided with this ITO transparent electrode was used as isopropyl alcohol. Ultrasonic cleaning was performed, followed by drying with dry nitrogen gas and UV ozone cleaning for 5 minutes. On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PS
S) was formed into a 50 nm film by a spin coating method at 2000 rpm for 60 seconds, and then vacuum dried at 110 ° C. for 1 hour.
A hole injection layer was produced.

On top of this, a poly (p-phenylene vinylene) (PPV) precursor solution was added at 1000 rpm for 2 minutes.
After forming a film with a thickness of 40 nm by the spin coating method in 0 seconds,
It vacuum-dried at 0 degreeC for 2 hours, and produced the light emitting layer.

Next, the substrate was fixed in a vacuum apparatus, the pressure in the tank was reduced to 1 × 10 ⁻⁴ Pa or less, and then LiF was adjusted to 0.5.
nm, and then Al was vapor-deposited to 100 nm to form an electron injection layer and a cathode. This was made into a comparative organic EL element 1-1.

Organic EL elements 1-2 to 1-16 and 1-19 of the present invention were prepared in the same manner as above except that the PPV of the light emitting layer was replaced with the compounds shown in Table 1.

When producing 1-17 and 1-18, the PEDOT / PSS layer was omitted except that the PPV of the light emitting layer was replaced with the compound shown in Table 1 above.

When preparing an inclusion complex, 0.01 mo
1 x 10 ^-6 mol per 1 / l host compound (cyclodextrin or cyclodextrin derivative)
/ L of guest compound is dimethylformamide and water 1:
It was dissolved in the mixed solution of No. 1 and stirred at room temperature for 1 hour to prepare.

The emission brightness and the emission life of the organic EL devices 1-1 to 1-19 were measured. The maximum luminance was measured with Minolta CS-1000. The light emission life was set to a half-life with an initial luminance of 100 cd / m ² by performing a life test on the device in a nitrogen gas atmosphere. Both the emission brightness and the emission lifetime are the organic EL device No. 1-
Table 1 shows the values (relative values) of the ratio of the emission luminance and the emission lifetime of each organic EL element sample when the emission lifetime of 1 was 100.

[0097]

[Table 1]

[0098]

[Chemical 10]

As is clear from Table 1, the electroluminescent device using the compound of the present invention in the light emitting layer has a high emission brightness and a long life, and has been found to be very useful as an organic EL device. . The host is a β-cyclodextrin derivative, which is most effective. Further, it can be seen that good performance is exhibited when the host compound and / or the guest compound is halogen-substituted.
The best case is when the cyclodextrin contains a hole transporting or electron transporting partial structure.

Example 2 After patterning was performed on a substrate (NA-45 manufactured by NH Techno Glass Co., Ltd.) on which ITO was formed in a thickness of 150 nm on glass as an anode, the transparent supporting substrate provided with this ITO transparent electrode was made of isopropyl alcohol. Ultrasonic cleaning, drying with dry nitrogen gas, and UV ozone cleaning were carried out for 5 minutes. On this transparent support substrate, poly (3,4-ethylenedioxythiophene) -polystyrene sulfonate (PEDOT / PS
S) was formed into a 50 nm film by a spin coating method at 2000 rpm for 60 seconds, and then vacuum dried at 110 ° C. for 1 hour.
A hole injection layer was produced.

Next, polyvinyl carbazole (PVK), which is a hole transporting material, is added to 2- (4 ') as an electron transporting material.
30% of -tert-butylphenyl) -5- (4'-biphenyl) -1,3,4-oxadiazole (TAZ)
10% by mass of β-cyclodextrin in a mass% ratio
Was added. Further, the iridium complex Ir-1 was doped at a ratio of 3 mass% and dissolved in dimethylformamide. A 100 nm film of this solution was formed on the hole injection layer by a spin coating method, and vacuum dried at 50 ° C. for 1 hour to obtain a light emitting layer.

Then, the substrate was fixed in a vacuum apparatus, the pressure in the tank was reduced to 1 × 10 ⁻⁴ Pa or less, and then LiF was adjusted to 0.5.
nm, and then Al was vapor-deposited to 100 nm to form an electron injection layer and a cathode. This organic EL element was designated as 2-1.

In the above, the organic EL devices 2-2 and 2 of the present invention were prepared in exactly the same manner except that the β-cyclodextrin in the light emitting layer was replaced with the inclusion compounds shown in 1-5 and 1-12 of Table 1. -3 was produced. Next, in the above, the β-cyclodextrin of the light emitting layer was replaced with 1-17 and 1-1 of Table 1.
Substituting the inclusion compound described in 8 and omitting PVK, organic EL devices 2-4 and 2-5 of the present invention were produced. In the above, the case where the β-cyclodextrin in the light emitting layer was replaced with the inclusion compound described in 1-19 of Table 1 and TAZ was omitted instead of PVK was designated as the organic EL element 2-6 of the present invention. The emission brightness and the emission life of the organic EL devices 2-1 to 2-6 were measured.

Regarding the emission brightness, the maximum brightness was measured with Minolta CS-1000. For the light emission life, the device was subjected to a life test in a nitrogen gas atmosphere, and the initial luminance was 100 cd /
The half-life was m ² . Organic EL element No. Table 2 shows the results of relative comparison when the emission luminance of 1-5 and the emission lifetime were each 100. The colored light was green.

[0105]

[Table 2]

As can be seen from Table 2, the introduction of the iridium complex showed a great effect. Iridium complex
Similar effects were also obtained in the organic EL elements produced in the same manner as the organic EL elements 2-1 to 2-6, except that the organic EL elements were replaced with r-9 or Ir-10. Note that blue light emission was obtained from the element using Ir-10 and red light emission was obtained from the element using Ir-9.

Example 3 The red, green, and blue light-emitting organic electroluminescent elements produced in Example 2 were placed side by side on the same substrate,
An active matrix full-color display device was manufactured.

By driving the full-color display device, clear full-color moving image display with high brightness was obtained.

[0109]

According to the present invention, it is possible to provide an organic electroluminescence device having high brightness and a long life, and a display device having a high brightness and a long life using the organic electroluminescence device of the present invention.

Front page continuation (51) Int.Cl. ⁷ Identification code FI theme code (reference) C09K 11/06 680 C09K 11/06 680 690 690 H05B 33/10 H05B 33/10 (72) Inventor Yoshiyuki Usari Tokyo 1st Sakura-cho, Hino City Konica Stock Association Internal F-term (reference) 3K007 AB02 AB11 AB18 DB03 FA01

Claims (12)

[Claims] 1. An organic electroluminescence device comprising a cyclodextrin. 2. An organic electroluminescence device comprising a cyclodextrin derivative. 3. An organic electroluminescence device comprising an inclusion complex of an organic compound and cyclodextrins. 4. An organic electroluminescence device comprising an inclusion complex of an organic compound and a cyclodextrin derivative. 5. The organic electroluminescence device according to claim 2 or 4, wherein the cyclodextrin derivative has a hole transporting ability or an electron transporting ability. 6. The organic electroluminescence device according to claim 2, 4 or 5, wherein the cyclodextrin derivative has triarylamine as a partial structure. 7. The organic electroluminescence device according to claim 3, wherein the organic compound is an aromatic hydrocarbon or a derivative thereof. 8. The organic electroluminescent device according to claim 1, wherein the cyclodextrin or the cyclodextrin derivative is β-cyclodextrin. 9. The organic electroluminescence according to claim 1, wherein the molecular structure of at least one of cyclodextrins, a cyclodextrin derivative, and an organic compound is halogen-substituted. element. 10. The organic electroluminescent device according to claim 1, which contains at least one of iridium, platinum, and an osmium complex. 11. The layer containing a compound is a layer which is formed by acting in a solution to form a coating solution and coating the coating solution.
An organic electroluminescence device according to the item 1. 12. A display device comprising the organic electroluminescence element according to claim 1. Description: