JP2017174598A - Organic EL element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element capable of suppressing decreases in emission reliability and lifetime due to ununiformity of a transparent conductive layer.SOLUTION: An organic EL element includes: a transparent base material 2; a thin wire structure 3 comprising a conductive material formed in a pattern shape on the transparent base material 2; a transparent conductive layer 4 formed on the transparent base material 2 and the thin wire structure 3; a cathode 6 formed on the transparent conductive layer 4; and an organic EL layer 5 formed between the transparent conductive layer 4 and the cathode 6, and including an organic light emitting layer comprising an organic matter. The maximum film thickness d1 from the top surface of the transparent base material 2 to the transparent conductive layer 4 on the thin wire structure 3, the minimum film thickness d2 of the transparent conductive layer 4 on the transparent base material 2, and the minimum film thickness d3 of the organic EL layer 5 satisfy a condition represented by expression (1). d1-d2≤d3...(1)SELECTED DRAWING: Figure 2

Description

  The present disclosure relates to an organic EL element.

In recent years, as a next-generation display device following a liquid crystal display element (LCD), research and development of a light-emitting device including a light-emitting element type display panel in which self-light-emitting elements such as organic EL (electroluminescence) elements are two-dimensionally arranged has been performed. ing.
The organic EL element includes an anode, a cathode, and an organic EL layer (light emitting functional layer) formed between the pair of electrodes, for example, having an organic light emitting layer and a hole injection layer. Further, the organic EL element emits light by energy generated by recombination of holes and electrons in the organic light emitting layer.

  As the transparent electrode on the light extraction side of such an organic EL element, in general, tin-doped indium oxide (ITO), zinc-doped indium oxide (IZO), or the like is used. Although formed, in order to obtain low resistance, a thick and uniform film must be formed. However, in order to achieve low resistance in such a transparent electrode, the light transmittance decreases, the price increases, and the high temperature treatment in the formation process occurs. Has a limit (see, for example, Patent Document 1).

  Therefore, in recent years, transparent electrode technology that does not use ITO has been disclosed. For example, a conductive structure in which at least one fine wire structure portion of a metal and an alloy such as a uniform mesh shape, a comb shape, or a grid shape is disposed. A transparent electrode is formed by, for example, forming a transparent conductive layer on the surface using, for example, an ink obtained by dissolving or dispersing a conductive polymer material in an appropriate solvent using a coating method or a printing method. Have been proposed (see, for example, Patent Document 2 and Patent Document 3).

Japanese Patent Application Laid-Open No. 10-162961 JP 2005-302508 A JP 2006-93123 A

  When using an ink application method or printing method in which a conductive polymer material is dispersed, after the ink is discharged or transferred onto the substrate, the solvent contained in the ink evaporates to dry and solidify the coating film. Become. However, in the drying process of the ink, the flow of the conductive polymer material is not uniform due to the influence of the shape of the conductive surface of the fine wire structure portion made of at least one of the metal and the alloy disposed under the coating film. In some cases, the formed transparent conductive layer becomes non-uniform to some extent.

  Depending on the non-uniformity of the transparent electrode, the film thickness of the organic EL layer formed on the transparent electrode may become non-uniform, and as a result, the electric field strength applied to the organic EL layer becomes non-uniform. In the region where the concentration of the organic EL element is concentrated, the organic EL layer (organic EL element) is significantly deteriorated. This problem becomes more prominent as the organic EL layer is thinner, and has a problem that the reliability and life of light emission are reduced.

  The present invention is intended to solve such problems, and an object of the present invention is to provide an organic EL element capable of suppressing light emission reliability and lifetime reduction due to non-uniformity of a transparent conductive layer. And

According to one aspect of the present invention, a transparent base material, a fine wire structure portion made of a conductive material formed in a lattice shape on the transparent base material, and a transparent material formed on the transparent base material and the fine wire structure portion. An organic EL layer comprising an electroconductive layer, a cathode formed on the transparent electroconductive layer, and an organic light emitting layer made of an organic material formed between the transparent electroconductive layer and the cathode. The maximum film thickness d1 from the upper surface to the transparent conductive layer on the thin wire structure, the minimum film thickness d2 of the transparent conductive layer on the transparent substrate, and the minimum film thickness d3 of the organic EL layer are ( 1) characterized by satisfying the condition of equation (1).
d1-d2 ≦ d3 (1)

  According to one embodiment of the present invention, there is provided an organic EL element capable of suppressing light emission reliability and lifetime reduction due to non-uniformity of a transparent conductive layer.

It is a top view which shows the organic EL element which concerns on one Embodiment of this invention. It is the II sectional view taken on the line of FIG.

  In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of embodiments of the present invention. However, it will be apparent that one or more embodiments may be practiced without such specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

<First Embodiment>
[Organic EL device]
Hereinafter, an organic EL element 1 according to a first embodiment of the present invention (hereinafter referred to as the present embodiment) will be described with reference to the drawings. FIG. 1 is a diagram showing a configuration of an organic EL element 1 according to this embodiment, and FIG. 2 is a cross-sectional view taken along a line II in FIG.
As shown in FIGS. 1 and 2, the organic EL element 1 includes a transparent substrate 2, a fine wire structure 3, a transparent conductive layer 4, an organic EL layer 5, and a cathode 6. 1 shows the organic EL element 1 in which the transparent conductive layer 4, the organic EL layer 5, and the cathode 6 are omitted. In addition, as shown in FIG. 2, the organic EL element 1 includes a transparent base material 2, a thin wire structure 3, a transparent conductive layer 4, an organic EL layer 5, and a cathode 6 formed in this order from the transparent base material 2 side. It is configured.

  When the fine wire structure portion 3 and the transparent conductive layer 4 are formed, the transparent conductive layer 4 is formed in a state where it rises on the side surface of the fine wire structure portion 3, and the uneven organic EL element 1 having an uneven surface shape is obtained. It is formed. This state was generally applied when a solution containing the material of the transparent conductive layer 4 was applied to a portion including the structure (thin wire structure portion 3 in the present embodiment) on the transparent substrate 2. In the process of drying the solution, it is a state that occurs when the solution in the drying process is attracted by capillary action at the contact point between the thin wire structure portion 3 and the transparent substrate 2.

  This non-uniformity of the transparent conductive layer 4 is suppressed to some extent by setting the minimum film thickness of the transparent conductive layer 4 in the range of 1 to 10 times the fine line height which is the height of the fine line structure portion 3. It becomes possible. Furthermore, the difference between the maximum film thickness from the transparent base material 2 to the transparent conductive layer 4 on the thin wire structure 3 and the minimum film thickness of the transparent conductive layer 4 on the transparent base material 2 is the minimum film thickness of the organic EL layer 5. It has been found empirically that the reliability of light emission and the decrease in lifetime can be suppressed even when the transparent conductive layer 4 becomes somewhat uneven by making the following.

That is, as shown in FIG. 1, the organic EL element 1 according to this embodiment has a maximum film thickness d <b> 1 from the upper surface of the transparent substrate 2 to the transparent conductive layer 4 on the thin wire structure 3, and the transparent substrate 2. The minimum film thickness d2 of the transparent conductive layer 4 and the minimum film thickness d3 of the organic EL layer 5 satisfy the condition of the following expression (1).
d1-d2 ≦ d3 (1)
In addition, the organic EL element 1 has a fine line height H that is the height of the fine line structure portion 3 in the thickness direction of the transparent base material 2 is 0.1 μm or more and 1.0 μm or less, and is the minimum film of the transparent conductive layer 4. The thickness d2 is 0.1 μm or more and 2.0 μm or less, and the fine wire height H and the minimum film thickness d2 of the transparent conductive layer 4 preferably satisfy the condition of the formula (2).
1 ≦ d2 / H ≦ 10 (2)

[Configuration of transparent substrate]
Next, a detailed configuration of the transparent substrate 2 will be described.
As the transparent substrate 2, a plastic film, a plastic plate, glass, or the like can be used.
Examples of the raw material for the plastic film and plastic plate used for the transparent substrate 2 include polyesters such as polyethylene terephthalate (PET) and polyethylene naphthalate, and polyolefins such as polyethylene (PE), polypropylene (PP), polystyrene and EVA. , Vinyl resins such as polyvinyl chloride and polyvinylidene chloride, polyether ether ketone (PEEK), polysulfone (PSF), polyether sulfone (PES), polycarbonate (PC), polyamide, polyimide, acrylic resin, or triacetyl Cellulose (TAC) can be used.

  In addition, the transparent substrate 2 is preferably excellent in surface smoothness. Specifically, the surface of the transparent substrate 2 preferably has an arithmetic average roughness Ra indicating smoothness of 5 nm or less and a maximum height Ry of 50 nm or less, more preferably an arithmetic average roughness. Ra is 1 nm or less, and the maximum height Ry is 20 nm or less.

  Further, the surface of the transparent substrate 2 may be smoothed by applying an undercoat layer such as a thermosetting resin, an ultraviolet curable resin, an electron beam curable resin, a radiation curable resin, or the like. It may be smoothed by machining. The surface of the transparent substrate 2 may be subjected to surface treatment with corona, plasma, or UV / ozone to improve the application and adhesion of the transparent conductive layer 4. The smoothness of the surface of the transparent substrate 2 can be calculated from measurement using an atomic force microscope (AFM) or the like.

  Furthermore, the transparent substrate 2 is preferably provided with a gas barrier layer for the purpose of blocking oxygen and moisture in the atmosphere. In this case, as a material for forming the gas barrier layer, for example, a metal oxide such as silicon oxide, silicon nitride, silicon oxynitride, aluminum nitride, or aluminum oxide, or a metal nitride can be used. These materials have an oxygen barrier function in addition to the water vapor barrier function. As a material for forming the gas barrier layer, silicon nitride or silicon oxynitride having particularly good barrier properties, solvent resistance, and transparency is preferable.

In addition, the gas barrier layer can have a multi-layer structure as necessary. In that case, you may comprise only with an inorganic layer and may comprise with an inorganic layer and an organic layer.
Furthermore, as a method for forming the gas barrier layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method can be used depending on the material. The thickness of the gas barrier layer is not particularly limited, but is preferably in the range of 5 nm to 500 nm per layer, and more preferably in the range of 10 nm to 200 nm per layer.
Further, the gas barrier layer is provided on at least one of the upper and lower surfaces facing the thickness direction of the transparent base material 2 (the vertical direction with respect to the paper surface of FIG. 2), and is provided on both the upper and lower surfaces of the transparent base material 2. More preferably.

[Thin wire structure]
Next, the detailed structure of the thin wire | line structure part 3 is demonstrated.
The thin wire structure portion 3 preferably has a low electric resistance, and as the material thereof, for example, a conductive material having an electric conductivity of 107 S / cm or more can be used.
As the conductive material, for example, at least one of metals such as aluminum, silver, chromium, gold, copper, tantalum, and molybdenum, and alloys of these metals can be used. Among these, aluminum, chromium, copper, silver, and alloys thereof are particularly preferable from the viewpoint of high electrical conductivity and easy material handling.

  In the present embodiment, a conductive mesh is formed by arranging a uniform mesh-like, comb-type or grid-type thin wire structure portion 3 formed using the above-described conductive material, thereby providing a conductive surface. Improves sex. The width of the thin wire of the metal or alloy is arbitrary, but is preferably in the range of 0.1 μm to 1000 μm. Further, the fine wires of the metal or alloy are preferably arranged at an interval pitch within a range of 50 μm or more and 5 cm or less, and particularly preferably an interval pitch within a range of 100 μm or more and 1 cm or less.

By disposing the thin wire structure 3 made of at least one of a metal and a metal alloy, the light transmittance is reduced, but it is important that the decrease in the transmittance is as small as possible. For this reason, it is important to ensure a light transmittance of 80% or more without excessively narrowing the interval between the thin lines or taking a large width of the fine lines.
Further, regarding the relationship between the fine line width and the fine line interval, the fine line width may be determined according to the purpose in terms of the planar arrangement, but is preferably within a range of 1/10000 or more and 1/5 or less of the fine line interval. 1/100 or more and 1/10 or less.

The fine wire height of the fine wire structure portion 3 made of at least one of metal and metal alloy is in the range of 0.1 μm or more and 1.0 μm or less. The fine wire height is the thickness of the fine wire structure portion 3 in the thickness direction of the transparent substrate 2, and is indicated by the symbol H in FIG.
Further, regarding the relationship between the fine line width and the fine line height H, the fine line height may be determined according to the desired conductivity, but is preferably used within a range of 1 / 10,000 to 10 times the fine line width. Further, the thin wire structure portion 3 can have a multi-layer structure as necessary. In that case, the fine wire structure part 3 may be comprised only with the same electrically-conductive material, and may be comprised with a different electrically-conductive material.

  The method for forming the fine wire structure 3 is not particularly limited. For example, the constituent material of the fine wire structure 3 by a resistance heating vapor deposition method, an electron beam vapor deposition method, a sputtering method, or a laminating method that thermally compresses a metal thin film. It is possible to use a method of forming the above-described pattern by an etching method using a photoresist after the film made of is formed.

Moreover, as a method of forming the fine wire structure part 3, for example, a method of forming a film from a solution containing a material that becomes the fine wire structure part 3 can be used. In this case, the solvent of the solution is not particularly limited as long as it dissolves the material that becomes the thin wire structure portion 3. Examples of the method for forming a film from a solution include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, and spray coating. It is possible to use coating methods such as a printing method, a screen printing method, a flexographic printing method, an offset printing method, a slit coating method, an ink jet printing method, and a nozzle printing method. In particular, a film forming method capable of directly forming the above-described pattern is preferable and can be selected as appropriate. However, a printing method such as a screen printing method, a flexographic printing method, an offset printing method, an ink jet printing method, or a nozzle printing method. A coating method by discharge or the like is preferable. In the method of forming the fine wire structure portion 3, the fine wire structure portion 3 is formed by applying the above solution onto the transparent substrate 2 and then drying and solidifying the solution.
In addition, as shown in FIG. 1, on the transparent base material 2, the area | region which is surrounded by the fine wire structure part 3 and the fine wire structure part 3 is not formed is called fine wire non-formation area | region D1.

[Configuration of transparent conductive layer]
Next, a detailed configuration of the transparent conductive layer 4 will be described.
As shown in FIG. 1, the transparent conductive layer 4 is formed on the transparent base material 2 and the thin line structure portion 3 by a coating method on a rectangular electrode formation region D2 indicated by a dotted line and covering the thin line non-formation region D1. . The solution used for the transparent conductive layer 4 includes a material to be the transparent conductive layer 4 and a solvent.
The material of the transparent conductive layer 4 preferably contains a polymer compound exhibiting conductivity. The polymer compound may contain a dopant. The conductivity of the polymer compound is 10 ^{−5 to} 10 ⁵ S / cm, preferably 10 ^{−3 to} 10 ⁵ S / cm in terms of conductivity. Moreover, it is preferable that the transparent conductive layer 4 consists of a high molecular compound which shows electroconductivity substantially.

As a material constituting the transparent conductive layer 4, for example, at least one of polyaniline and a derivative thereof, or at least one of polythiophene and a derivative thereof can be used. A known dopant can be used as the dopant, and examples thereof include organic sulfonic acids such as polystyrene sulfonic acid and dodecylbenzene sulfonic acid, and Lewis acids such as PF ₅ , AsF ₅ , and SbF ₅ . Further, the polymer compound exhibiting conductivity may be a self-doped polymer compound in which a dopant is directly bonded to the polymer compound.

The transparent conductive layer 4 is preferably configured to include at least one of polythiophene and derivatives thereof. In this case, it is preferable that substantially consists of at least one of polythiophene and its dielectric. Note that polythiophene or a dielectric thereof may contain a dopant.
A polythiophene, a polythiophene derivative, or a mixture of a polythiophene and a polythiophene derivative is easily dissolved or dispersed in an aqueous solvent such as water and alcohol, and thus is preferably used as a solute of a coating solution used in a coating method. Moreover, these have high electroconductivity and are used suitably as an electrode material. Furthermore, these have a HOMO energy of about 5.0 eV, and the difference from the HOMO energy of an organic light emitting layer used in a normal organic electroluminescence device is as low as about 1 eV, so that holes are efficiently injected into the organic light emitting layer. In particular, it can be suitably used as an anode material. Moreover, these have high transparency and are suitably used as an electrode on the light emission extraction side of the organic electroluminescence element.

Furthermore, the transparent conductive layer 4 is preferably configured to include at least one of polyaniline and its dielectric, and substantially consists of at least one of polyaniline and its dielectric. Note that at least one derivative of polyaniline and polyaniline may contain a dopant.
A polyaniline, a polyaniline dielectric, or a mixture of a polyaniline and a polyaniline dielectric is preferably used as an electrode material because of its excellent conductivity and stability. Moreover, these have high transparency and are suitably used as an electrode on the light emission extraction side of the organic electroluminescence element.

  Examples of the method for forming the transparent conductive layer 4 include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, Application methods such as screen printing, flexographic printing, offset printing, slit coating, ink jet printing, and nozzle printing can be used. In particular, since the transparent conductive layer 4 is formed over the entire surface of the electrode formation region D2, a method of uniformly coating and forming is preferable and can be selected as appropriate, but a spin coat method, a bar coat method, a wire bar can be selected. Coating methods such as a coating method, a dip coating method, a spray coating method, a slit coating method, a casting method, a micro gravure coating method, a gravure coating method, and a roll coating method are suitable.

And the transparent base material 2 with which the coating electrically-conductive material was apply | coated to the whole electrode formation area D2 is heat-processed on the temperature conditions of 100 degreeC or more, for example in a drying process chamber. Thereby, the solvent contained in the solution containing the applied conductive material is vaporized, and the applied conductive material is fixed on the transparent base material 2 and the thin wire structure portion 3 to form the transparent conductive layer 4.
In addition, the anode having a transparent conductive layer disposed on the thin wire structure portion of the present embodiment has a surface resistivity of 0.01Ω / □ from the viewpoint of improving luminance when used in an organic EL element. It is preferably in the range of 100Ω / □ or less, and more preferably in the range of 0.1Ω / □ or more and 10Ω / □ or less.

[Configuration of organic EL element]
Next, a detailed configuration of the organic EL element 1 will be described.
In the organic EL element 1, a thin wire structure portion 3, a transparent conductive layer 4 used as an anode, an organic EL layer 5, and a cathode 6 are sequentially formed on a transparent substrate 2.
The organic EL layer 5 and the cathode 6 can be made of any material and configuration generally used for organic EL elements. The organic EL layer 5 is a layer between the anode and the cathode.

As an element structure of an organic electroluminescent element, it is possible to use the thing of various structures, such as (A)-(E) shown below, for example.
(A) Anode / organic light emitting layer / cathode (B) Anode / hole transport layer / organic light emitting layer / electron transport layer / cathode (C) Anode / hole injection layer / hole transport layer / organic light emitting layer / electron transport Layer / cathode (D) anode / hole injection layer / organic light emitting layer / electron transport layer / electron injection layer / cathode (E) anode / hole injection layer / organic light emitting layer / electron injection layer / cathode

The symbol “/” shown in the above (A) to (E) indicates that the layers sandwiching the symbol “/” are stacked adjacent to each other. The same applies to the following description.
Moreover, the organic EL element 1 is good also as a structure which has two or more organic light emitting layers. As an organic electroluminescent element having two or more organic light emitting layers, for example, the layer configuration shown in the following (F) can be used.
(F) Anode / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / charge generation layer / charge injection layer / hole transport layer / organic light emission layer / electron transport layer / charge injection layer /cathode

As an organic electroluminescence device having three or more organic light emitting layers, specifically, (charge generation layer / charge injection layer / hole transport layer / organic light emission layer / electron transport layer / charge injection layer) As a single repeating unit, a layer structure including two or more repeating units shown in (G) below can be used.
(G) Anode / charge injection layer / hole transport layer / organic light emitting layer / electron transport layer / charge injection layer / (the repeating unit) / (the repeating unit) /.

In the above layer configuration, each layer other than the anode, cathode, and organic light emitting layer can be deleted as necessary.
Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. As the charge generation layer, for example, a thin film made of vanadium oxide, ITO, molybdenum oxide, or the like can be used.
Hereinafter, a layer provided between the anode and the organic light emitting layer, a hole injection layer, a hole transport layer, an organic light emitting layer, a layer provided between the cathode and the light emitting layer, an electron transport layer, an electron injection layer, and a cathode Each layer will be described.

[Layer provided between cathode and light-emitting layer]
Examples of the layer provided between the cathode and the organic light emitting layer as needed include an electron injection layer, an electron transport layer, a hole blocking layer, and the like. When both the electron injection layer and the electron transport layer are provided between the cathode and the organic light emitting layer, the layer in contact with the cathode is called an electron injection layer, and the layers other than the electron injection layer are the electron transport layer. That's it.

The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode.
The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or a layer closer to the cathode.
The hole blocking layer is a layer having a function of blocking hole transport.
In the case where at least one of the electron injection layer and the electron transport layer has a function of blocking hole transport, these layers may also serve as the hole blocking layer.

[Hole injection layer]
The hole injection layer can be provided between the anode and the hole transport layer, or between the anode and the organic light emitting layer.
As a material constituting the hole injection layer, a known material can be appropriately used, and there is no particular limitation. Therefore, as a material constituting the hole injection layer, for example, phenylamine, starburst amine, phthalocyanine, hydrazone derivative, carbazole derivative, triazole derivative, imidazole derivative, oxadiazole derivative having amino group, oxidation Oxides such as vanadium, tantalum oxide, and molybdenum oxide, amorphous carbon, polyaniline, polythiophene derivatives, and the like can be used.

As a method for forming a hole injection layer, a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or a vapor deposition method, or a material to be used as a hole injection layer (hole injection) It is possible to use film formation from a solution containing the material.
The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material, for example, a chlorine-based solvent such as chloroform, methylene chloride, dichloroethane, an ether-based solvent such as tetrahydrofuran, Aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, or water can be used.

Examples of film forming methods from solutions include spin coating, casting, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, dip coating, spray coating, and screen printing. It is possible to use a coating method such as a printing method, a flexographic printing method, an offset printing method, a slit coating method, an ink jet printing method, or a nozzle printing method.
The thickness of the hole injection layer is preferably in the range of 5 nm to 300 nm. This is because manufacturing tends to be difficult when the thickness of the hole injection layer is less than 5 nm. On the other hand, if the thickness of the hole injection layer exceeds 300 nm, the driving voltage and the voltage applied to the hole injection layer tend to increase.

[Hole transport layer]
The hole transport material constituting the hole transport layer is not particularly limited. For example, N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD) ), 4,4′-bis [N- (1-naphthyl) -N-phenylamino] biphenyl (NPB) and other aromatic amine derivatives, polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, side chain or main chain Polysiloxane derivative having aromatic amine, pyrazoline derivative, arylamine derivative, stilbene derivative, triphenyldiamine derivative, polyaniline or derivative thereof, polythiophene or derivative thereof, polyarylamine or derivative thereof, polypyrrole or derivative thereof, poly (p- Phenylene vinylene) or derivatives thereof, or poly (2, 5-thienylene vinylene) or a derivative thereof can be used.

  As the hole transport material used for the hole transport layer, among the materials described above, polyvinyl carbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative polyaniline having an aromatic amine in a side chain or a main chain, or a material thereof Polymeric hole transport materials such as derivatives, polythiophene or derivatives thereof, polyarylamines or derivatives thereof, poly (p-phenylene vinylene) or derivatives thereof, or poly (2,5-thienylene vinylene) or derivatives thereof are preferred. In the case of a low-molecular hole transport material, it is preferably used by being dispersed in a polymer binder.

The method for forming the hole transport layer is not particularly limited, but a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, a sputtering method, or a polymer hole As the transport material, film formation from a solution containing a hole transport material can be used.
The solvent used for film formation from a solution is not particularly limited as long as it can dissolve a hole transport material, and the solvent exemplified in the section of the hole injection layer can be used as an example. It is. In addition, as a film formation method from a solution, a coating method similar to the film formation method of the hole injection layer described above can be used.

  The thickness of the hole transport layer is not particularly limited, but can be appropriately changed according to the intended design, and is preferably in the range of 1 nm to 1000 nm, for example. This is because when the thickness of the hole transport layer is less than 1 nm, production tends to be difficult and the effect of hole transport cannot be obtained sufficiently. On the other hand, when the thickness of the hole transport layer exceeds 1000 nm, the driving voltage and the voltage applied to the hole transport layer tend to increase. Therefore, the thickness of the hole transport layer is preferably in the range of 1 nm to 1000 nm, more preferably in the range of 2 nm to 500 nm, and still more preferably in the range of 5 nm to 200 nm. It is.

[Organic light emitting layer]
The organic light emitting layer has an organic substance (a low molecular compound and a high molecular compound) that mainly emits fluorescence or phosphorescence. The organic light emitting layer may further contain a dopant material.
As a material for forming the organic light emitting layer, for example, the following pigment materials, metal complex materials, polymer materials, and the like can be used.

(Dye material)
Examples of the dye-based material include cyclopentamine derivatives, quinacudrine derivatives, coumarin derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, A pyrrole derivative, a thiophene ring compound, a pyridine ring compound, a perinone derivative, a perylene derivative, an oligothiophene derivative, an oxadiazole dimer, a pyrazoline dimer, or the like can be used.

(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., center metal having Al, Zn, Be or the like, or rare earth metal such as Tb, Eu, Dy, etc., and the ligand is oxadiazole, thiadiazole, phenylpyridine, It is possible to use a metal complex having a phenylbenzimidazole, a quinoline structure, or the like.

(Polymer material)
High molecular weight materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized light emitting materials of the above dye bodies or metal complexes. Etc. can be used.
Among the light-emitting materials described above, as a material emitting blue light, a distyrylarylene derivative, an oxadiazole derivative and a polymer thereof, a polyvinylcarbazole derivative, a polyparaphenylene derivative, a polyfluorene derivative, or the like can be used. is there.

In addition, among the light-emitting materials described above, as a material that emits green light, a quinacrine derivative, a coumarin derivative and a polymer thereof, a polyparaphenylene vinylene derivative, a polyfluorene derivative, or the like can be used.
Among the above-described light emitting materials, as a material emitting red light, a coumarin derivative, a thiophene ring compound and a polymer thereof, a polyparaphenylene vinylene derivative, a polythiophene derivative, a polyfluorene derivative, or the like can be used. .

(Dopant material)
Furthermore, a dopant can be added to the organic light emitting layer for the purpose of improving the light emission efficiency and changing the light emission wavelength.
As the dopant, for example, a perylene derivative, a coumarin derivative, a rubrene derivative, a quinacdrine derivative, a squalium derivative, a porphyrin derivative, a styryl dye, a tetracene derivative, a pyrazolone derivative, decacyclene, phenoxazone, and the like can be used. The thickness of the organic light emitting layer is usually in the range of about 5 nm to 200 nm.

  As a method for forming the organic light emitting layer, a vapor deposition method such as a resistance heating vapor deposition method, an electron beam vapor deposition method, a reactive vapor deposition method, an ion plating method, or a sputtering method, or a film formation from a solution containing an organic light emitting material is used. It is possible. Further, the solvent used for film formation from a solution is not particularly limited as long as it dissolves an organic light emitting material, and the solvent exemplified in the section of the hole injection layer can be used as an example. is there. In addition, as a film formation method from a solution, a coating method similar to the film formation method of the hole injection layer described above can be used.

[Layer provided between cathode and light-emitting layer]
Examples of the layer provided between the cathode and the organic light emitting layer as needed 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 between the cathode and the organic light emitting layer, a layer in contact with the cathode is referred to as an electron injection layer, and a layer excluding this electron injection layer is referred to as an electron transport layer.
The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode.

The electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer, or a layer closer to the cathode.
The hole blocking layer is a layer having a function of blocking hole transport.
When at least one of the electron injection layer and the electron transport layer has a function of blocking hole transport, these layers may also serve as a hole blocking layer.

[Electron transport layer]
As the electron transport material constituting the electron transport layer, known materials can be used. For example, oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinone or Derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone or derivatives thereof, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, Alternatively, polyfluorene or a derivative thereof can be used.

  Among these, examples of the electron transport material include oxadiazole derivatives, benzoquinone or derivatives thereof, anthraquinones or derivatives thereof, metal complexes of 8-hydroxyquinoline or derivatives thereof, polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or Its derivatives are preferred, and 2- (4-biphenylyl) -5- (4-tert-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum, or polyquinoline preferable.

The method for forming the electron transport layer is not particularly limited, and vapor deposition methods such as resistance heating vapor deposition, electron beam vapor deposition, reactive vapor deposition, ion plating, and sputtering can be used.
The film thickness of the electron transport layer varies depending on the material used and can be changed as appropriate according to the intended design. However, at least a film thickness that does not cause pinholes is required. Therefore, the thickness of the electron transport layer is preferably, for example, in the range of 1 nm to 1000 nm, more preferably in the range of 2 nm to 500 nm, and still more preferably in the range of 5 nm to 200 nm. Within range.

[Electron injection layer]
As a material constituting the electron injection layer, an optimal material is appropriately selected according to the type of the organic light emitting layer, and includes, for example, at least one of alkali metal, alkaline earth metal, alkali metal, and alkaline earth metal. It is possible to use alloys, alkali metal or alkaline earth metal oxides, halides, carbonates or mixtures of these substances.

  Examples of the alkali metal, alkali metal oxide, halide and carbonate include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, Rubidium oxide, rubudium fluoride, cesium oxide, cesium fluoride, lithium carbonate, or the like can be used.

  Examples of the alkaline earth metal, alkaline earth metal oxide, halide and carbonate include, for example, magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, Barium fluoride, strontium oxide, strontium fluoride, magnesium carbonate, or the like can be used.

Note that the electron injection layer may be formed of a stacked body in which two or more layers are stacked. In this case, as a material constituting the electron injection layer, for example, lithium fluoride / calcium can be used.
The electron injection layer is formed by various deposition methods, sputtering methods, various coating methods, and the like. The thickness of the electron injection layer is preferably in the range of 1 nm to 1000 nm.

[cathode]
As a material for the cathode, it is preferable to use at least one material among a material having a small work function and easy electron injection into the organic light emitting layer, a material having a high electrical conductivity, and a material having a high visible light reflectance. Specifically, as a material for the cathode, for example, a metal, a metal oxide, an alloy, graphite, a graphite intercalation compound, an inorganic semiconductor such as zinc oxide, or the like can be used.

  Moreover, as a metal used as a material of a cathode, it is possible to use an alkali metal, alkaline-earth metal, a transition metal, a III-b group metal etc., for example. Specific examples of these metals include lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin , Aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, and the like.

  Moreover, as an alloy used as a material of a cathode, it is possible to use the alloy containing at least 1 type among the metals mentioned above. Specifically, magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, etc. can be used. It is.

The cathode is a transparent electrode as necessary, and examples of the material include conductive oxides such as indium oxide, zinc oxide, tin oxide, ITO and IZO, polyaniline or a derivative thereof, polythiophene or a derivative thereof, and the like. It is possible to use a conductive organic material.
Note that the cathode may have a laminated structure of two or more layers. Moreover, you may use an electron injection layer as a cathode.
The thickness of the cathode can be appropriately selected in consideration of electrical conductivity and durability, but is, for example, in the range of 10 nm to 10000 nm, preferably in the range of 20 nm to 1000 nm. More preferably, it is in the range of 50 nm or more and 500 nm or less.

[Uses of organic electroluminescence elements]
The organic EL element 1 of this embodiment can be used for a self-luminous display, a liquid crystal backlight, illumination, and the like. Moreover, since the organic EL element 1 of this embodiment can be made to light-emit uniformly and uniformly, it is preferable to use for an illumination use.

  Although the present invention has been described above with reference to specific embodiments, it is not intended that the present invention be limited by these descriptions. From the description of the invention, other embodiments of the invention will be apparent to persons skilled in the art, along with various variations of the disclosed embodiments. Therefore, it is to be understood that the claims encompass these modifications and embodiments that fall within the scope and spirit of the present invention.

<Effect of embodiment>
(1) An organic EL element 1 according to an aspect of the present invention includes a transparent substrate 2, a fine wire structure portion 3 made of a conductive material formed in a pattern on the transparent substrate 2, a transparent substrate 2 and a fine wire. Organic including a transparent conductive layer 4 formed on the structure 3, a cathode 6 formed on the transparent conductive layer 4, and an organic light emitting layer made of an organic material formed between the transparent conductive layer 4 and the cathode 6. An EL layer 5, a maximum film thickness d1 from the upper surface of the transparent substrate 2 to the transparent conductive layer 4 on the thin wire structure 3, a minimum film thickness d2 of the transparent conductive layer 4 on the transparent substrate 2, and an organic The minimum film thickness d3 of the EL layer 5 satisfies the condition of the expression (1).
d1-d2 ≦ d3 (1)
According to the configuration (1), it is possible to suppress the light emission reliability and the lifetime from being reduced even when the transparent conductive layer becomes uneven to some extent.

(2) In the configuration of (1) above, the fine wire height H, which is the height of the fine wire structure part 3 in the thickness direction of the transparent substrate 2, is 0.1 μm or more and 1.0 μm or less, and the transparent conductive layer 4 The minimum film thickness d2 is 0.1 μm or more and 2.0 μm or less, and the fine line height H and the minimum film thickness d2 of the transparent conductive layer 4 satisfy the condition of the expression (2).
1 ≦ d2 / H ≦ 10 (2)
According to the configuration of (2) above, the non-uniformity of the transparent conductive layer 4 can be suppressed, and the light emission reliability and lifetime can be further suppressed.

DESCRIPTION OF SYMBOLS 1 Organic EL element 2 Transparent base material 3 Fine wire structure part 4 Transparent conductive layer 5 Organic EL layer 6 Cathode D1 Fine wire non-formation area D2 Electrode formation area

Claims (2)

A transparent substrate;
A fine wire structure portion made of a conductive material formed in a lattice shape on the transparent substrate;
A transparent conductive layer formed on the transparent substrate and the fine wire structure; and
A cathode formed on the transparent conductive layer;
An organic EL layer including an organic light emitting layer made of an organic material formed between the transparent conductive layer and the cathode,
Maximum film thickness d1 from the upper surface of the transparent substrate to the transparent conductive layer on the thin wire structure, minimum film thickness d2 of the transparent conductive layer on the transparent substrate, and minimum film thickness of the organic EL layer An organic EL element, wherein d3 satisfies the condition of formula (1).
d1-d2 ≦ d3 (1) The fine wire height H, which is the height of the fine wire structure part in the thickness direction of the transparent substrate, is 0.1 μm or more and 1.0 μm or less,
The minimum film thickness d2 of the transparent conductive layer is 0.1 μm or more and 2.0 μm or less,
2. The organic EL element according to claim 1, wherein the fine wire height H and the minimum film thickness d <b> 2 of the transparent conductive layer satisfy the condition of the expression (2).
1 ≦ d2 / H ≦ 10 (2)

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