JP2009205985A - Organic electroluminescent element, and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent element having a negative electrode capable of suppressing formation of a quenching region and reduction of the film thickness of an organic semiconductor part, and achieving high current density and low voltage drive; and its manufacturing method. <P>SOLUTION: This organic EL element includes: a positive electrode 21; a negative electrode 41; and a luminescent layer 30 sandwiched between the positive electrode 21 and the negative electrode 41, and containing an organic compound. The negative electrode 41 is formed by stacking a plurality of negative electrode layers formed of materials different from one another. A first negative electrode layer 41 out of the plurality of negative electrode layers contains Ag, O and Cs. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an organic electroluminescence element (hereinafter sometimes referred to as “organic EL element” in the present specification), and more specifically, an organic electroluminescence element comprising an anode, a cathode, and a light emitting layer containing an organic compound. And a manufacturing method thereof.

One element that emits light when a voltage is applied is an organic EL element. The organic EL element generally has an anode, a cathode, and a light emitting layer sandwiched between them. The light emitting layer is formed of an organic compound that emits light when voltage is applied.
Organic EL elements are used in light sources, lighting devices, and the like, and are required to have element characteristics that emit light with high luminance while having a low driving voltage. In particular, elements for large displays such as televisions are used to reduce power consumption. There is a need for further low-voltage driving. As a conventional knowledge for obtaining low voltage driving in a polymer light emitting device, a method of increasing current density using a Cs-based inorganic compound such as CsF or Cs ₂ CO ₃ as a cathode has been proposed (for example, non-patent document). 1).

Journal Of Applied Physics, 2003, 93, p. 6159-p. 6172

However, when a conventional Cs-based inorganic compound (CsF, Cs ₂ CO _3, etc.) is used as the material of the cathode, Cs diffuses deeply into the organic light-emitting layer, a quenching region is formed, and the semiconductor portion of the organic light-emitting layer As the film thickness of the film decreases, there is a problem that it is impossible to achieve both low voltage driving and high luminance.

  Under the circumstances as described above, an object of the present invention is to have a cathode capable of suppressing the formation of the quenching region and the reduction in the thickness of the semiconductor portion of the organic light-emitting layer, thereby realizing both low voltage driving and high luminance. An organic electroluminescence device and a manufacturing method thereof are provided.

In order to solve the above-mentioned problems, the present inventors have intensively studied and studied an Ag—O—Cs compound produced from Cs ₂ CO ₃ and Ag. The knowledge that Cs diffusion into the layer can be suppressed has been obtained, and the present invention has been completed. That is, this invention provides the following organic electroluminescent element and its manufacturing method.

  A first invention includes an anode, a cathode, and a light emitting layer sandwiched between the anode and the cathode and containing an organic compound, and the cathode is configured by laminating a plurality of cathode layers made of different materials. In the organic electroluminescence device, the first cathode layer of the plurality of cathode layers contains Ag, O, and Cs.

  A second invention is the organic electroluminescence device according to the first invention, wherein the first cathode layer contains Ag, O, Cs, and C.

A third invention is the organic electroluminescence device according to the second invention, wherein the first cathode layer is formed by a co-evaporation method using Cs ₂ CO ₃ and Ag.

  A fourth invention is the organic electroluminescence according to any one of the first to third inventions, wherein the second cathode layer in contact with the first cathode layer contains at least one of Ag and Al. In the element.

  A fifth invention is the organic electroluminescence device according to the fourth invention, wherein the first cathode layer is disposed between the second cathode layer and the light emitting layer.

  A sixth invention is characterized in that in any one of the first to fifth inventions, the molar ratio of Ag and Cs contained in the first cathode layer is 1: 9 to 8: 2. It is in an electroluminescence element.

  A seventh invention is an organic electroluminescence device according to any one of the first to sixth inventions, wherein the organic compound is a polymer compound.

An eighth invention is an organic electroluminescent element manufacturing method for forming an anode, a cathode, and a light emitting layer sandwiched between the anode and the cathode and containing an organic compound, wherein the cathodes are mutually connected A plurality of cathode layers of different materials are laminated and a first cathode layer of the plurality of cathode layers is formed using Cs ₂ CO ₃ and Ag. Is in the way.

  According to a ninth aspect of the present invention, there is provided the method for producing an organic electroluminescent element according to the eighth aspect, wherein the first cathode layer is formed by a co-evaporation method.

  A tenth aspect of the invention is a planar light source using the organic electroluminescence element according to any one of the first to seventh aspects.

  An eleventh aspect of the invention is a segment display device using the organic electroluminescence element according to any one of the first to seventh aspects.

  A twelfth aspect of the invention is a dot matrix display device using the organic electroluminescence element according to any one of the first to seventh aspects.

  A thirteenth aspect of the invention is a liquid crystal display device characterized in that the organic electroluminescence element according to any one of the first to seventh aspects is used as a backlight.

  According to the present invention, a cathode made of Ag—O—Cs that suppresses formation of a quenching region and a reduction in film thickness of a semiconductor portion of an organic light emitting layer is provided, and low voltage driving and high luminance are realized in a polymer light emitting device.

Hereinafter, embodiments of the present invention will be described. The present invention is not limited to the following description, and can be appropriately changed without departing from the gist of the present invention.
1. The organic EL device of the present invention includes an anode, a cathode, and a light emitting layer sandwiched between the anode and the cathode and containing an organic compound, and the cathode includes a plurality of cathode layers made of different materials. And the first cathode layer of the plurality of cathode layers includes Ag, O, and Cs.

That is, in the present invention, by using, for example, an Ag—O—Cs compound composed of Cs ₂ CO ₃ and Ag as the first cathode layer, the intrinsic high electron injection ability of the Cs system is As it is, the diffusion of Cs into the light emitting layer is suppressed.

  The molar ratio of Ag and Cs contained in the first cathode layer is preferably 1: 9 to 8: 2 in order to suppress a decrease in film thickness.

Here, the first cathode layer is preferably formed as an Ag—O—Cs compound by co-evaporation with Cs ₂ CO ₃ and Ag.
The film thickness of the first cathode layer is 0.5 to 20 nm, preferably about 2 to 8 nm.
The second cathode layer that protects the first cathode layer formed in contact with the first cathode layer is a layer made of Ag or Al, and the film thickness is preferably about 80 nm. As a method for producing the second cathode layer, a vacuum deposition method, a sputtering method, a laminating method in which a metal thin film is thermocompression bonded, or the like is used.

Here, the penetration ratio of the Cs component with respect to the organic light emitting layer which is an organic semiconductor layer can be estimated using the following formula (1).
d = ε ₀ × ε _r × S / C (1)
Here, d is the thickness of the semiconductor portion of the organic light emitting layer, C is the capacitance, S is the light emitting area of the element, ε ₀ is the vacuum dielectric constant, and ε _r is the relative dielectric constant.

  By measuring the electric capacity of the element using the light emitting area of the element and the dielectric constant of the organic light emitting layer, the substantial film thickness of the semiconductor portion of the organic light emitting layer of the element can be estimated.

  By forming the first cathode layer with a material containing Cs, the portion where Cs invades in the light emitting layer becomes a conductor, so that the actual film thickness calculated from Equation (1) is calculated to be thin.

As shown in Examples to be described later, when only a conventionally known Cs-based compound is used as the first cathode layer, the actual film thickness of the organic light emitting layer calculated from the formula (1) is based on the film formation process design value. It became significantly thinner. Specifically, when the film formation process design value was 100 nm, the actual film thickness was as thin as 45 nm.
On the other hand, when the Ag—O—Cs compound of the present invention was used, this decrease in the substantial film thickness was largely suppressed. Specifically, when the film formation process design value was 100 nm, the substantial film thickness was reduced to 75 nm.
The device using the Ag—O—Cs compound of the present invention for the first cathode layer was driven at a low voltage.

  Thus, according to the organic electroluminescence device according to the present invention, a cathode made of an Ag—O—Cs compound that suppresses formation of the quenching region and reduction in the thickness of the organic light emitting layer is provided. Voltage drive and high brightness are realized.

  Although the organic electroluminescent element of this invention is not limited, an example of embodiment of an organic EL element is shown in FIG. FIG. 1 is a front view schematically showing the configuration of the organic electroluminescence element of the present invention. The organic EL device of the embodiment shown in FIG. 1 includes an anode 21, a hole injection layer 22, a hole transport layer 23, a light emitting layer 30, an electron transport layer 43, and an electron injection layer in order from the support substrate 10 side. 42 and the cathode 41 are laminated.

  The cathode 41 is configured by laminating two or more cathode layers. In the present embodiment, the cathode 41 is composed of a first cathode layer 41-1, a second cathode layer 41-2, and a third cathode layer 41-3. Consists of layers. The first cathode layer 41-1 is preferably disposed at the remaining position of the plurality of cathode layers excluding the cathode layer farthest from the light emitting layer 30, and more preferably the most light emitting layer among the plurality of cathode layers. 30 side. In the present embodiment, the cathode 41 is laminated in the order of the first cathode layer 41-1, the second cathode layer 41-2, and the third cathode layer 41-3 from the light emitting layer 30 side. The cathode 41 is preferably in contact with an organic layer containing an organic material such as the electron transport layer 43, the electron injection layer 42, and the light emitting layer 30, and the cathode 41 and the light emitting layer 30 are in contact as shown in FIG. Is more preferable.

  As another configuration of the cathode 41, the arrangement of the first cathode layer 41-1 and the second cathode layer 41-2 is interchanged so that the second cathode layer 41-2 is a light emitting layer of the first cathode layer 41-1. You may arrange | position in contact with 30 side.

Therefore, according to the organic electroluminescence device according to the present invention as shown in FIG. 2, light emission is obtained by using, for example, an Ag—O—Cs compound composed of Cs ₂ CO ₃ and Ag as the first cathode layer 41-1. Cs diffusion into the layer 30 can be suppressed.

  Further, even when the first cathode layer 41-1 is in contact with the electron injection layer 42, the electron transport layer 43, and the like as in the organic electroluminescence device according to the present invention as shown in FIG. 1, the first cathode layer 41- The diffusion of Cs into organic layers such as the electron injection layer 42 and the electron transport layer 43 with which 1 is in contact can be suppressed.

  Further, as shown in FIG. 3, a thin insulating layer 44 such as a lithium fluoride layer may be provided between the first cathode layer 41-1 and the organic layer such as the electron injection layer. .

  As a modification, the cathode layer 41 may be provided on the support substrate 10, and the anode 21 may be provided on the light emitting layer 30. Further, as another modification example, any type of organic EL element of a bottom emission type that performs daylighting from the support substrate 10 side, a top emission type that performs daylighting from the opposite side of the support substrate 10, or a double-sided daylighting type may be used. . As yet another modification, a layer having other functions such as an arbitrary protective film, buffer film, and reflective layer may be provided. The configuration of the organic EL element will be described in detail later. The organic EL element is further covered with a sealing substrate to form an organic EL device in which the organic EL element is shielded from the outside air.

<Organic EL device>
Next, the embodiment of the organic EL element of the present invention will be described more specifically. The production method of the present invention is a method of producing an organic electroluminescent element which is sandwiched between an anode, a cathode, and the anode and the cathode and forms a light emitting layer containing an organic compound, wherein the cathodes are mutually A plurality of cathode layers of different materials are stacked to form a film, and the first cathode layer of the plurality of cathode layers is formed using Cs ₂ CO ₃ and Ag. In addition, the manufacturing method of this invention is not necessarily limited to the following organic EL element.

  In addition to having an anode, a light emitting layer, and a cathode as essential, the organic EL element further includes a light emitting layer and a light emitting layer between the anode and the light emitting layer and / or between the light emitting layer and the cathode. Can have different other layers.

  Examples of the layer that can be provided between the cathode and the light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer. When both the electron injection layer and the electron transport layer are provided, the layer close to the cathode is the electron injection layer, and the layer close to the light emitting layer is the electron transport layer.

  The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode, and the electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer or the electron transport layer closer to the cathode. is there. In addition, when the electron injection layer or the electron transport layer has a function of blocking hole transport, these layers may also serve as the hole blocking layer.

  Examples of what is provided between the anode and the light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. When both the hole injection layer and the hole transport layer are provided, the layer close to the anode is the hole injection layer, and the layer close to the light emitting layer is the hole transport layer.

  The hole injection layer is a layer having a function of improving the hole injection efficiency from the anode, and the hole transport layer is a hole injection layer from the anode, the hole injection layer or the hole transport layer closer to the anode. It is a layer having a function of improving. In addition, when the hole injection layer or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron block layer.

  In an organic EL element, one light emitting layer is usually provided, but not limited to this, two or more light emitting layers may be provided. In that case, two or more light-emitting layers can be stacked in direct contact, and a metal oxide layer or the like used in the present invention can be provided between the light-emitting layer and the light-emitting layer.

  Note that the electron injection layer and the hole injection layer may be collectively referred to as a charge injection layer, and the electron transport layer and the hole transport layer may be collectively referred to as a charge transport layer.

More specifically, the organic EL device can have any of the following layer configurations:
a) Anode / hole transport layer / light emitting layer / cathode b) Anode / light emitting layer / electron transport layer / cathode c) Anode / hole transport layer / light emitting layer / electron transport layer / cathode d) Anode / charge injection layer / Emissive layer / cathode e) anode / emission layer / charge injection layer / cathode f) anode / charge injection layer / emission layer / charge injection layer / cathode g) anode / charge injection layer / hole transport layer / emission layer / cathode h ) Anode / hole transport layer / light emitting layer / charge injection layer / cathode i) Anode / charge injection layer / hole transport layer / light emitting layer / charge injection layer / cathode j) Anode / charge injection layer / light emitting layer / charge transport Layer / cathode k) anode / light emitting layer / electron transport layer / charge injection layer / cathode l) anode / charge injection layer / light emitting layer / electron transport layer / charge injection layer / cathode m) anode / charge injection layer / hole transport Layer / light emitting layer / charge transport layer / cathode n) anode / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode o) anode / charge injection layer / Hole transport layer / light emitting layer / electron transporting layer / charge injection layer / cathode (wherein, / indicates that each layer is laminated adjacently. Hereinafter the same.)

  In each example of the layer configuration, the metal oxide layer is provided as at least one of a hole transport layer, an electron transport layer, or a charge injection layer.

The organic EL element may have two or more light emitting layers.
Specifically, as an organic EL element having two light emitting layers,
p) of anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / charge generation layer / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode The thing which has a layer structure is mentioned.
In addition, as an organic EL device having three or more light emitting layers, specifically, a charge generation layer / charge injection layer / hole transport layer / light emission layer / electron transport layer / charge injection layer are formed as one repeating unit (hereinafter referred to as “repeating unit”). As “repeating unit A”)
q) Layer structure including anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / repeat unit A / repeat unit A... / cathode and two or more repeat units A The thing which has.
In the layer structures p and q, each layer other than the anode, the electrode, the cathode, and the light emitting layer can be omitted as necessary.
Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the material constituting the electrode include vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, and the like.
In each example of the layer configurations p and q, the metal oxide layer is provided as at least one of a charge injection layer, a hole transport layer, or an electrode.

  In order to emit light from the light emitting layer, the organic EL element normally has a transparent layer on either side of the light emitting layer. Specifically, for example, in the case of an organic EL device having a configuration of anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode / sealing member, the anode, the charge injection layer, and the positive electrode All of the hole transport layers are transparent, so-called bottom emission type elements, or all of the electron transport layer, the charge injection layer, the cathode and the sealing member are transparent, so-called top emission type elements, can do. In the case of an organic EL device having a structure of cathode / charge injection layer / electron transport layer / light emitting layer / hole transport layer / charge injection layer / anode / sealing member, all of the cathode, charge injection layer and electron transport layer Can be made a so-called bottom emission type element, or all of the hole transport layer, the charge injection layer, the anode and the sealing member can be made transparent to make a so-called top emission type element. . Here, the term “transparent” means that the visible light transmittance from the light emitting layer to the light emitting layer is 40% or more. In the case of an element that requires light emission in the ultraviolet region or infrared region, a device having a transmittance of 40% or more in the region is preferable.

The organic EL element may further include the charge injection layer or an insulating layer having a thickness of 2 nm or less adjacent to the electrode in order to improve adhesion with the electrode or improve charge injection from the electrode. A thin buffer layer may be inserted at the interface between the charge transport layer and the light emitting layer in order to improve the adhesion at the interface or prevent mixing.
The order and number of layers to be laminated, and the thickness of each layer can be appropriately used in consideration of light emission efficiency and element lifetime.

  Next, the material (excluding the cathode) of each layer constituting the organic EL element and the forming method will be described more specifically.

<Board>
The substrate constituting the polymer light emitting device of the present invention may be any substrate as long as it does not change when an electrode is formed and an organic layer is formed, such as glass, plastic, polymer film, metal film, silicon substrate, and the like. A laminate of these is used. A commercially available substrate is available as the substrate, or can be manufactured by a known method.
When the polymer light emitting device of the present invention constitutes a pixel of a display device, a pixel driving circuit may be provided on the substrate, or a flattening film is provided on the driving circuit. Also good. When a planarizing film is provided, it is preferable that the center line average roughness (Ra) of the planarizing film satisfies Ra <10 nm.

<Anode>
As the anode of the organic EL element, the work function of the surface of the anode on the light emitting layer side is 4. from the viewpoint of supplying holes to an organic semiconductor material used in a hole injection layer, a hole transport layer, a light emitting layer and the like. It is preferably 0 eV or more.
When the organic EL element is a so-called bottom emission element, it is preferable to use a transparent or translucent electrode because an element that emits light through the anode can be formed.
When the organic EL element is a so-called top emission type element, a material that reflects light may be used.
As a material of such an anode, a metal, an alloy, a metal oxide, a metal sulfide, an electrically conductive compound, a mixture thereof, or the like can be used, which is appropriately selected depending on an organic layer to be used. Specifically, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO), conductive metal oxides such as molybdenum oxide, gold, platinum, silver, copper, chromium, nickel, etc. And a mixture of these conductive metal oxides and metals. Alternatively, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.
Such an anode may have a single layer structure composed of one or more of these materials, or a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  Examples of the manufacturing method include a vacuum evaporation method (including an electron beam evaporation method), a sputtering method, an ion plating method, and a plating method.

  The film thickness of the anode can be appropriately selected in consideration of light transmittance and electrical conductivity, and is, for example, 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm. is there.

<Hole injection layer>
The hole injection layer can be provided between the anode and the hole transport layer or between the anode and the light emitting layer.
In the polymer light-emitting device of the present invention, the material for forming the hole injection layer includes carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine. Derivatives, arylamine derivatives, starburst amines, phthalocyanine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidins Compounds, porphyrin compounds, polysilane compounds, poly (N-vinylcarbazole) derivatives, organic silane derivatives, and polymers containing these, vanadium oxide Arm, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide, aluminum oxide, amorphous carbon. In addition, conductive polymer oligomers such as polyaniline, aniline copolymers, thiophene oligomers and polythiophenes, organic conductive materials such as poly (3,4-ethylenedioxythiophene) / polystyrenesulfonic acid and polypyrrole, Coalescence can be mentioned. Further, tetracyanoquinodimethane derivatives (for example, 2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane), 1,4-naphthoquinone derivatives, diphenoquinone derivatives, polynitro compounds, etc. The acceptor organic compound can also be suitably used.
The material may be a single component or a composition comprising a plurality of components. In addition, the hole injection layer may have a single layer structure composed of one or more of the materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. The materials listed as materials that can be used in the hole transport layer can also be used in the hole injection layer.

  The film thickness of the hole injection layer is usually in the range of 1 nm to 150 nm, preferably 20 nm or more from the viewpoint of film flatness, and preferably 80 nm or less from the viewpoint of device driving voltage.

  Although there is no restriction | limiting in the film-forming method of a positive hole injection layer, The method by the film-forming from a mixed solution with a polymer binder is illustrated by the low molecular hole injection material. In the case of a polymer hole injection material, a method by film formation from a solution is exemplified.

  The solvent used for film formation from a solution is not particularly limited as long as it can dissolve the hole injection material. Examples of the solvent include chlorine solvents such as chloroform, methylene chloride, and dichloroethane; ether solvents such as tetrahydrofuran; aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone and methyl ethyl ketone; ethyl acetate, butyl acetate, Examples include ester solvents such as ethyl cellosolve acetate or water.

  Examples of film formation methods from solution include spin coating from solution, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, slit coating method, capillary Coating methods such as coating methods, spray coating methods, nozzle coating methods, etc., gravure printing methods, screen printing methods, flexographic printing methods, offset printing methods, reverse printing methods, printing methods such as inkjet printing methods, etc. may be used. it can. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reversal printing method, and an inkjet printing method is preferable in that the pattern formation is easy.

  As the polymer binder to be mixed, those not extremely disturbing charge transport are preferable, and those showing no strong absorption against visible light are suitably used. Examples of the polymer binder include polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane.

  The film thickness of the hole injection layer varies depending on the material used, and may be selected so that the drive voltage and the light emission efficiency are appropriate. However, at least a thickness that does not cause pinholes is required. If it is too thick, the driving voltage of the element becomes high, which is not preferable. Accordingly, the thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
Examples of the material constituting the hole transport layer include carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino acids. Substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly (N- Vinylcarbazole) derivatives, organosilane derivatives, and polymers containing these structures. In addition, conductive polymer oligomers such as aniline copolymers, thiophene oligomers, and polythiophenes, and organic conductive materials such as polypyrrole can also be used. The material may be a single component or a composition comprising a plurality of components. The hole transport layer may have a single layer structure composed of one or more of the materials, or a multilayer structure composed of a plurality of layers having the same composition or different compositions.

  Specifically, JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209998, JP-A-3-37992, JP-A-3-152184, Compounds disclosed in Kaihei 5-263073, JP-A-6-1972, WO2005 / 52027, JP-A-2006-295203, and the like can be used as the hole transporting material. Among these, a polymer containing a repeating unit containing the structure of an aromatic tertiary amine compound is preferably used.

  Examples of the repeating unit including the structure of the aromatic tertiary amine compound include a repeating unit represented by the following general formula (1).

Wherein, Ar ^1, Ar ^2, Ar ³ and Ar ⁴ represent each independently an optionally substituted arylene group or may have a substituent group a divalent heterocyclic group, Ar ⁵ , Ar ⁶ and Ar ⁷ represent an aryl group which may have a substituent or a monovalent heterocyclic group which may have a substituent, and n and m are each independently 0 or 1 And 0 ≦ n + m ≦ 2.
In the formula, the hydrogen atom on the aromatic ring is a halogen atom, alkyl group, alkyloxy group, alkylthio group, aryl group, aryloxy group, arylthio group, arylalkyl group, arylalkyloxy group, arylalkylthio group, alkenyl group, alkynyl Group, arylalkenyl group, arylalkynyl group, acyl group, acyloxy group, amide group, acid imide group, imine residue, substituted amino group, substituted silyl group, substituted silyloxy group, substituted silylthio group, substituted silylamino group, cyano group, A substituent selected from a nitro group, a monovalent heterocyclic group, a heteroaryloxy group, a heteroarylthio group, an alkyloxycarbonyl group, an aryloxycarbonyl group, an arylalkyloxycarbonyl group, a heteroaryloxycarbonyl group and a carboxyl group It may be substituted.
Substituents include vinyl, acetylene, butenyl, acrylic, acrylate, acrylamide, methacryl, methacrylate, methacrylamide, vinyl ether, vinylamino, silanol, and small rings (for example, cyclo A propyl group, a cyclobutyl group, an epoxy group, an oxetane group, a diketene group, an episulfide group, etc.), a lactone group, a lactam group, or a cross-linking group such as a group containing a structure of a siloxane derivative. In addition to the above groups, combinations of groups capable of forming an ester bond or an amide bond (for example, an ester group and an amino group, an ester group and a hydroxyl group, etc.) can be used as a crosslinking group.
Furthermore, Ar ² and Ar ³ may be bonded directly or via a divalent group such as O or S.
Examples of the arylene group include a phenylene group, and examples of the divalent heterocyclic group include a pyridinediyl group. These groups may have a substituent.
Examples of the aryl group include a phenyl group and a naphthyl group, and examples of the monovalent heterocyclic group include a pyridyl group. These groups may have a substituent.

The polymer containing the repeating unit containing the structure of the aromatic tertiary amine compound may further have another repeating unit. Other repeating units include arylene groups such as a phenylene group and a fluorenediyl group.
Of these polymers, those containing a crosslinking group are more preferred.

  Although there is no restriction | limiting in the film-forming method of a positive hole transport layer, In the low molecular hole transport material, the method by the film-forming from a mixed solution with a polymer binder is illustrated. In the case of a polymer hole transport material, a method of film formation from a solution is exemplified.

  The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material. Examples of the solvent include chlorine solvents such as chloroform, methylene chloride, and dichloroethane; ether solvents such as tetrahydrofuran; aromatic hydrocarbon solvents such as toluene and xylene; ketone solvents such as acetone and methyl ethyl ketone; ethyl acetate, butyl acetate, An ester solvent such as ethyl cellosolve acetate is exemplified.

  Examples of film formation methods from solution include spin coating from solution, casting method, micro gravure coating method, gravure coating method, bar coating method, roll coating method, wire bar coating method, dip coating method, slit coating method, capillary Coating methods such as coating methods, spray coating methods, nozzle coating methods, etc., gravure printing methods, screen printing methods, flexographic printing methods, offset printing methods, reverse printing methods, printing methods such as inkjet printing methods, etc. may be used. it can. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reversal printing method, and an inkjet printing method is preferable in that the pattern formation is easy.

  As the polymer binder to be mixed, those not extremely disturbing charge transport are preferable, and those showing no strong absorption against visible light are suitably used. Examples of the polymer binder include polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, and polysiloxane.

  When the hole transporting material is a low molecular compound such as a pyrazoline derivative, an arylamine derivative, a stilbene derivative, or a triphenyldiamine derivative, the hole transport layer can be formed using a vacuum deposition method. In addition, these low molecular hole transport materials may be poly (N-vinylcarbazole), polyaniline or derivatives thereof, polythiophene or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, poly (2,5-thienylene vinylene). ) Or its derivatives, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, polyvinyl chloride, polysiloxane, etc., a high molecular compound that does not extremely inhibit charge transport and does not strongly absorb visible light The hole transport layer may be formed by a coating method using the mixed solution dispersed in the solution.

When forming the light-emitting layer following the hole transport layer, especially when both layers are formed by a coating method, the solvent contained in the coating solution used when the previously formed layer forms the layer later. It may become impossible to create a laminated structure by dissolving in In this case, a method of making the lower layer solvent insoluble can be used. As a method for making the solvent insoluble, a method in which a crosslinking group is synthetically attached to the polymer compound itself, a low molecular compound having a crosslinking group having an aromatic ring represented by aromatic bisazide is mixed as a crosslinking agent. Cross-linking method, a method of cross-linking by mixing a low molecular weight compound having a cross-linking group represented by an acrylate group as a cross-linking agent, and heating the lower layer to insolubilize it in an organic solvent used for making the upper layer And the like. When heating the lower layer, the heating temperature is usually about 150 ° C. to 300 ° C., and the time is usually about 1 minute to 1 hour.
As another method of laminating without dissolving the lower layer except for crosslinking, there is a method using a solution with a different polarity as a solution for forming adjacent layers, for example, a polymer that does not dissolve in a polar solvent in the lower layer. There is a method in which a lower layer is not dissolved even when a coating liquid containing a polymer compound and a polar solvent is applied in the production of an upper layer using a compound.

  The film thickness of the hole transport layer differs depending on the material used, and may be selected so that the drive voltage and the light emission efficiency are appropriate. However, at least a thickness that does not cause pinholes is required. If it is too thick, the driving voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the hole transport layer and the interlayer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

  Examples of the method for forming the hole transport layer include the same methods as those for forming the hole injection layer. A method of applying a solution containing a hole transport material on or above the substrate, a vacuum deposition method, and a transfer method. Etc. can be used. Specific examples of the solvent used for the film formation from the solution include the same solvents as those used for dissolving the hole injection material when forming the hole injection layer from the above solution.

<Light emitting layer>
The light emitting layer contains an organic compound. Usually, organic substances (low molecular compounds and high molecular compounds) that mainly emit fluorescence or phosphorescence are included. Further, a dopant material may be further included. Examples of the material for forming the light emitting layer that can be used in the present invention include the following dye materials, metal complex materials, dopant materials, and polymer materials.

[Dye-based materials]
Examples of dye-based materials include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, thiophene ring compounds. Pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, trifumanylamine derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

[Metal complex materials]
Examples of the metal complex material include metal complexes that emit light from triplet excited states such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyls. Zinc complex, porphyrin zinc complex, europium complex, etc., which has Al, Zn, Be or the like as the central metal or rare earth metal such as Tb, Eu, or Dy, and the ligand is oxadiazole, thiadiazole, phenylpyridine, phenylbenzo Examples thereof include metal complexes having an imidazole or quinoline structure.

[Dopant material]
A dopant can be added to the light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength. Examples of such dopants include perylene derivatives, coumarin derivatives, rubrene derivatives, quinacridone derivatives, squalium derivatives, porphyrin derivatives, styryl dyes, tetracene derivatives, pyrazolone derivatives, decacyclene, phenoxazone, and the like. In addition, the thickness of such a light emitting layer is about 20-2000 mm normally.

[Polymer material]
Polymeric materials include polyfluorene derivatives (PF), polyparaphenylene vinylene derivatives (PPV), polyphenylene derivatives (PP), polyparaphenylene derivatives (PPP), polythiophene derivatives, polydialkylfluorene (PDAF), polyfluorene benzo Examples thereof include conjugated polymer compounds such as thiadiazole (PFBT) and polyalkylthiophene (PAT), and polymers obtained by polymerizing the above dye bodies and metal complex luminescent materials.

Among the light-emitting materials, examples of materials that emit blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.
Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.
Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, polyfluorene derivatives and the like are preferable.

  In addition, the light-emitting layer of the light-emitting element of the present invention includes a non-conjugated polymer compound [for example, polyvinyl carbazole, polyvinyl chloride, polycarbonate, polystyrene, polymethyl methacrylate, polybutyl methacrylate, polyester, polysulfone, polyphenylene oxide, polybutadiene, Poly (N-vinylcarbazole), hydrocarbon resin, ketone resin, phenoxy resin, polyamide, ethyl cellulose, vinyl acetate, ABS resin, polyurethane, melamine resin, unsaturated polyester resin, alkyd resin, epoxy resin, silicone resin, and carbazole derivatives , Triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenedi Amine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, A polysilane compound, a poly (N-vinylcarbazole) derivative, a polymer containing an organic silane derivative] and a light-emitting organic compound such as the organic dye or metal complex may be used.

As such a compound, examples of the polymer luminescent material include WO99 / 13692, WO99 / 48160, GB2340304A, WO00 / 53656, WO01 / 19834, WO00 / 55927, GB23448316, WO00 / 46321, WO00 / 06665, WO99 / 54943, WO99 / 54385, US5777070, WO98 / 06773, WO97 / 05184, WO00 / 35987, WO00 / 53655, WO01 / 34722, WO99 / 24526, WO00 / 22027, WO00 / 22026, WO98 / 27136, US573636, WO98 / 21262, US5741921, WO97 / 09394, WO96 / 29356, WO96 / 10617, EP07007020, WO95 / 0 955, JP 2001-181618, JP 2001-123156, JP 2001-3045, JP 2000-351967, JP 2000-303066, JP 2000-299189, JP 2000-252065, JP 2000-136379, Polyfluorenes, derivatives and copolymers thereof disclosed in JP-A Nos. 2000-104057, 2000-80167, 10-324870, 10-114891, 9-111233, 9-45478, etc. , Polyarylene, derivatives and copolymers thereof, polyarylene vinylene, derivatives and copolymers thereof, and (co) polymers of aromatic amines and derivatives thereof.
Examples of the fluorescent material of low molecular weight compounds include compounds described in JP-A-57-51781, JP-A-59-194393, and the like.

<Method for forming light emitting layer>
As a method for forming a light emitting layer containing an organic substance, a method of applying a solution containing a light emitting material on or above a substrate, a vacuum deposition method, a transfer method, or the like can be used. Specific examples of the solvent used for the film formation from the solution include the same solvents as those for dissolving the hole transport material when forming the hole transport layer from the above solution.

  As a method for applying a solution containing a light emitting material on or above a substrate, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method Coating methods such as slit coating method, capillary coating method, spray coating method, nozzle coating method, gravure printing method, screen printing method, flexographic printing method, offset printing method, reverse printing method, inkjet printing method, etc. A coating method can be used. A printing method such as a gravure printing method, a screen printing method, a flexographic printing method, an offset printing method, a reversal printing method, and an ink jet printing method is preferable in that pattern formation and multi-coloring are easy. In the case of a sublimable low-molecular compound, a vacuum deposition method can be used. Furthermore, a method of forming a light emitting layer only at a desired place by laser transfer or thermal transfer can be used.

  As the film thickness of the light emitting layer, the optimum value varies depending on the material used, and it may be selected so that the drive voltage and the light emission efficiency are appropriate values, but at least a thickness that does not cause pinholes is required, If the thickness is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the light emitting layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 10 nm to 200 nm.

<Electron transport layer and hole blocking layer>
As materials constituting the electron transport layer and the hole blocking layer, known materials can be used, such as triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones. Or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, anthraquinodimethane derivatives, anthrone derivatives, thiopyran dioxide oxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives , Distyrylpyrazine derivatives, aromatic tetracarboxylic anhydrides such as naphthalene and perylene, phthalocyanine derivatives, 8-quinolinol derivatives , Metal phthalocyanine, and metal complexes various metal complexes having benzoxazole or benzothiazole as represented by metal complexes having a ligand, organic silane derivatives, and the like. Further, the electron transport layer and the hole blocking layer may have a single layer structure composed of one or more of the materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions. Good. In addition, materials listed as materials that can be used in the electron injection layer can also be used in the hole injection layer.

  Of these, oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, or metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof are preferred, 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, polyquinoline are preferred.

  There are no particular restrictions on the method for forming the electron transport layer and the hole blocking layer. However, in the case of a low molecular weight electron transport material, a vacuum evaporation method from powder or a method by film formation from a solution or a molten state is used as a polymer electron. Examples of the transport material include a method of film formation from a solution or a molten state. When forming a film from a solution or a molten state, a polymer binder may be used in combination. Examples of the method for forming the electron transport layer and the hole blocking layer from the solution include the same film formation method as the method for forming the hole transport layer from the above solution.

  The film thicknesses of the electron transport layer and the hole blocking layer differ depending on the materials used, and may be selected so that the drive voltage and the light emission efficiency are appropriate. If the thickness is too thick, the driving voltage of the element increases, which is not preferable. Therefore, the thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Electron injection layer>
The electron injection layer is provided between the electron transport layer and the cathode or between the light emitting layer and the cathode. As the electron injection layer, materials listed as materials that can be used in the electron transport layer and the hole blocking layer can also be used in the electron injection layer. The electron injection layer may be a laminate of two or more layers. The electron injection layer is formed by vapor deposition, sputtering, printing, or the like. The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

<Insulating layer>
The insulating layer having a film thickness of 2 nm or less that the polymer light emitting device of the present invention can optionally have has a function of facilitating charge injection. Examples of the material for the insulating layer include metal fluorides, metal oxides, and organic insulating materials. As the polymer light emitting device having an insulating layer having a thickness of 2 nm or less, an insulating layer having a thickness of 2 nm or less is provided adjacent to the cathode, and an insulating layer having a thickness of 2 nm or less is provided adjacent to the anode. Is mentioned.

  The organic EL device of the present invention can be used as a backlight for a planar light source, a segment display device, a dot matrix display device, and a liquid crystal display device.

  In order to obtain planar light emission using the organic EL device of the present invention, the planar anode and cathode may be arranged so as to overlap each other. In addition, in order to obtain pattern-like light emission, a method of installing a mask provided with a pattern-like window on the surface of the planar light-emitting element, an organic material layer of a non-light-emitting portion is formed extremely thick and substantially non- There are a method of emitting light and a method of forming either one of the anode or the cathode or both electrodes in a pattern. By forming a pattern by any of these methods and arranging several electrodes so that they can be turned on and off independently, a segment type display device capable of displaying numbers, letters, simple symbols, and the like can be obtained. Further, in order to obtain a dot matrix element, both the anode and the cathode may be formed in a stripe shape and arranged so as to be orthogonal to each other. Partial color display and multicolor display are possible by a method of separately applying a plurality of types of light emitting materials having different emission colors or a method using a color filter or a fluorescence conversion filter. The dot matrix element can be driven passively or may be driven actively in combination with TFTs. These display elements can be used as display devices for computers, televisions, mobile terminals, mobile phones, car navigation systems, video camera viewfinders, and the like.

  Furthermore, the planar light-emitting device is self-luminous and thin, and can be suitably used as a planar light source for a backlight of a liquid crystal display device or a planar illumination light source. If a flexible substrate is used, it can be used as a curved light source or display device.

Examples illustrating the effects of the present invention will be described below, but the present invention is not limited to these examples.
<Example 1>

A hole injection material solution was applied on a glass substrate on which an ITO anode was formed and patterned as an anode, and a hole injection layer was formed by spin coating so that the film thickness was 60 nm.
The formed glass substrate was heated at 200 ° C. for 10 minutes to insolubilize the hole injection layer, and the substrate was naturally cooled to room temperature.
Here, PEDOT: PSS solution (poly (3,4-ethylenedioxythiophene) / polystyrene sulfonic acid, “Product name: Baytron”) available from Stark Vitec Co., Ltd. is used as the hole injection material solution. It was.

  A hole transporting polymer material and xylene were mixed to obtain a composition for forming a hole transporting layer containing 0.7% by weight of the hole transporting polymer material.

Next, a composition for forming a hole transport layer was applied onto the hole injection layer by a spin coating method to obtain a coating film having a thickness of 20 nm.
The substrate provided with this coating film was heated at 190 ° C. for 20 minutes to insolubilize the coating film, and then naturally cooled to room temperature to obtain a hole transport layer.

  The light emitting polymer material and xylene were mixed to obtain a composition for forming a light emitting layer in which the light emitting polymer material was 1.4% by weight.

On the hole transport layer of the substrate having the anode, the hole injection layer, and the hole transport layer obtained above, the composition for forming a light emitting layer was applied by a spin coating method, and a coating film having a thickness of 80 nm was formed. Obtained.
The substrate provided with this coating film was heated at 130 ° C. for 20 minutes to evaporate the solvent and then naturally cooled to room temperature to obtain a light emitting layer.

A first cathode layer was formed by vacuum deposition on the light emitting layer formed substrate obtained above. Deposition method is a co-evaporation method, the vapor deposition source using Cs ₂ CO ₃ and Ag, the film formation conditions were as follows.
(1) Degree of vacuum: 2.0 ⁻⁴ Pa or less (2) Cs ₂ CO ₃ deposition rate: 0.7 Å / s
(3) Ag deposition rate: 0.3 Å / s
(4) Deposition rate by the sum of Cs ₂ CO ₃ and Ag: 1.0 Å / s
(5) Film thickness of the first cathode layer by the sum of Cs ₂ CO ₃ and Ag: 3 nm

  Subsequently, 80 nm of Ag was continuously formed as the second cathode layer.

  Next, the substrate on which the cathode film was formed was taken out of the vacuum apparatus, and sealed with sealing glass and a two-component mixed epoxy resin in an inert (nitrogen) atmosphere, whereby a light emitting device 1 was obtained.

<Comparative Example 1>
As in Example 1, it was deposited to the light emitting layer by a vacuum deposition method, and the only Cs ₂ CO ₃ containing no Ag as the cathode layer corresponding to the first cathode layer and 3nm deposited.

  Subsequently, 80 nm of Ag was continuously formed as a cathode layer corresponding to the second cathode layer.

  Next, sealing was performed in the same manner as in Example 1 to obtain a light-emitting element 2.

<Reference example>
Similarly to Example 1, the layers up to the light emitting layer were formed, and Ba was deposited in a thickness of 5 nm as a cathode layer corresponding to the first cathode layer by vacuum deposition.

  Subsequently, 80 nm of Ag was continuously formed as a cathode layer corresponding to the second cathode layer.

  Next, sealing was performed in the same manner as in Example 1 to obtain a light-emitting element 3.

<Evaluation of film thickness of organic light emitting layer>
The capacitance of the device was measured with an Agilent LCR meter, and the film thickness d of the semiconductor portion of the device was evaluated from the following formula (1).

d = ε ₀ × ε _r × S / C (1)
Here, d is the thickness of the semiconductor portion, C is the capacitance, S is the light emitting area of the element, ε ₀ is the vacuum dielectric constant, and ε _r is the relative dielectric constant, where S = 4 mm ² , ε _r = 1. It was set to 6.

  Table 1 below shows the film thickness at the time of forming the organic light emitting layer (film thickness at the time of film formation) and the film thickness d of the semiconductor portion of the organic light emitting layer estimated from the capacitance of each element.

  From the results of Table 1, it can be seen that the semiconductor part evaluation film thickness of Comparative Example 1 (light emitting element 2) employing the conventional inorganic compound cathode containing Cs is significantly smaller than the film thickness during film formation.

  On the other hand, it was found that the semiconductor part evaluation film thickness of Example 1 (Light-Emitting Element 1) of the present invention was significantly smaller than that of Comparative Example 1.

<Electrical characteristics>

  Table 2 shows the light emission luminance when a forward voltage of 4 V is applied to each element.

  From the results of “Table 2”, it was found that the emission luminance of Example 1 (Light Emitting Element 1) of the present invention was significantly higher than that of Comparative Example 1 (Light Emitting Element 2) employing the conventional inorganic compound cathode containing Cs. did.

  In addition, it was found that the emission luminance of Example 1 (light-emitting element 1) of the present invention was significantly higher than that of the conventional element (light-emitting element 3) employing a compound not containing Cs, and was driven at a low voltage.

  From the results of the above examples, according to the present invention, it is possible to realize an organic EL element that achieves both low voltage driving and high emission luminance.

  As described above, the present invention is useful in the industrial field related to the organic EL device.

It is a front view which shows simply the structure of one Embodiment of the organic EL element of this invention. It is a front view which shows simply the other structure of one Embodiment of the organic EL element of this invention. It is a front view which shows simply the other structure of one Embodiment of the organic EL element of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Support substrate 21 Anode 22 Hole injection layer 23 Hole transport layer 30 Light emitting layer 41 Cathode 41-1 1st cathode layer 41-2 2nd cathode layer 41-3 3rd cathode layer 42 Electron injection layer 43 Electron transport layer 44 Insulation layer

Claims (13)

The anode,
A cathode,
A light emitting layer sandwiched between the anode and the cathode and containing an organic compound,
The cathode is configured by laminating a plurality of cathode layers made of different materials, and the first cathode layer of the plurality of cathode layers includes Ag, O, and Cs. In claim 1,
The organic electroluminescence device, wherein the first cathode layer contains Ag, O, Cs, and C. In claim 2,
The organic electroluminescent device, wherein the first cathode layer is formed by a co-evaporation method using Cs ₂ CO ₃ and Ag. In any one of Claims 1 thru | or 3,
The organic electroluminescence element, wherein the second cathode layer in contact with the first cathode layer contains at least one of Ag and Al. In claim 4,
The organic electroluminescence device, wherein the first cathode layer is disposed between the second cathode layer and the light emitting layer. In any one of Claims 1 thru | or 5,
The organic electroluminescence device, wherein a molar ratio of Ag and Cs contained in the first cathode layer is 1: 9 to 8: 2. In any one of Claims 1 thru | or 6,
The organic electroluminescence device, wherein the organic compound is a polymer compound. A method for producing an organic electroluminescent element, comprising forming an anode, a cathode, and a light emitting layer sandwiched between the anode and the cathode and containing an organic compound,
The cathode is formed by stacking a plurality of cathode layers made of different materials, and a first cathode layer of the plurality of cathode layers is formed using Cs ₂ CO ₃ and Ag. A method for manufacturing an organic electroluminescence element. In claim 8,
A method for producing an organic electroluminescence element, wherein the first cathode layer is formed by a co-evaporation method. A planar light source using the organic electroluminescence element according to claim 1. A segment display device using the organic electroluminescence element according to claim 1. A dot matrix display device using the organic electroluminescence element according to claim 1. A liquid crystal display device comprising the organic electroluminescence element according to claim 1 as a backlight.

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