JP2010192472A - Organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-photon organic EL device that has high light-extraction efficiency by increasing a light quantity generated inside the organic EL device, and also to provide a lighting apparatus, a planar light source, and a display apparatus. <P>SOLUTION: An organic EL device 10 is equipped with: a support substrate 15; a positive electrode (a first electrode) 14 provided in contact with the support substrate 15 and having the light permeability; a negative electrode (a second electrode) 16 being the other electrode; first/second light-emitting units 11, 12 provided between both electrodes and respectively including an organic light-emitting layer; and a charge generating layer 13 arranged while being sandwiched by the first/second light-emitting units. The charge generating layer 13 includes one or more kinds selected from the group (A) consisting of metals and compounds of the metals respectively having a work function of ≤3.0 eV, and one or more kinds of compounds (B) respectively having a work function of ≥4.0 eV. Each of the refractive index n1 of the positive electrode 14 and the refractive index n2 of the support substrate 15 satisfis a formula (1). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an organic electroluminescence element (hereinafter sometimes referred to as an organic EL element), a lighting device, a planar light source, and a display device.

  The organic EL element includes a pair of electrodes and a light emitting layer containing an organic compound provided between the electrodes (hereinafter sometimes referred to as an organic light emitting layer). When a voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and light is emitted by combining these holes and electrons in the organic light emitting layer.

  A normal organic EL element includes one organic light emitting layer. Naturally, a light emitting element is required to emit light with high luminance. Therefore, an organic EL element including two or more organic light emitting layers responsible for light emission has been studied. For example, a so-called multiphoton type organic EL element having a structure in which a plurality of light emitting units including an organic light emitting layer are stacked has been proposed. Note that an organic EL element having high characteristics cannot be obtained by simply laminating a light emitting unit including an organic light emitting layer. Therefore, a predetermined charge generation layer is provided between the light emitting units (for example, see Patent Document 1). .

  The organic EL element is usually provided on a substrate. A so-called bottom emission type organic EL element emits light from the substrate side through an electrode and a substrate disposed near the substrate of the pair of electrodes. Therefore, a transparent electrode is used as an electrode disposed near the substrate. As such a transparent electrode, a thin film made of a metal oxide such as indium tin oxide (ITO) is known (for example, see Patent Document 2).

JP 2003-272860 A

  The multi-photon type organic EL element has a complicated structure as compared with a normal organic EL element having a single organic light emitting layer. However, by constructing the multi-photon type organic EL element, Since the amount of light generated in is increased, the luminance can be improved. However, for the purpose of increasing the amount of light generated in the element, even if a multi-photon type structure having a complicated structure is used, a part of the light generated in the element is reflected on the substrate surface or the like. In addition, the luminance of the organic EL element is not necessarily sufficient because it does not emit to the outside.

  The present invention has been made in view of the above-described problems in the prior art, and the problems thereof are a multiphoton type organic EL element having high light extraction efficiency and high brightness, an illumination device including the organic EL element, and a planar light source. And providing a display device.

を満たす、
有機エレクトロルミネッセンス素子。
［２］ 前記発光ユニットが、塗布法により形成されてなる有機発光層を含む、上記［１］に記載の有機エレクトロルミネッセンス素子。
［３］ 前記有機発光層が、高分子有機化合物を含む、上記「１」又は［２］に記載の有機エレクトロルミネッセンス素子。
［４］ 前記電荷発生層が、前記群（Ａ）から選ばれるものの１種類以上を含む第１の層と、前記化合物（Ｂ）の１種類以上を含む第２の層とを含んで成り、前記第１の層が、前記第２の層よりも、前記陽極としての第１または第２電極寄りに配置される、上記［１］から［３］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［５］ 前記電荷発生層は、前記群（Ａ）から選ばれるものの１種類以上と、前記化合物（Ｂ）の１種類以上とが混合されてなる層である、上記［１］から［３］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［６］ 前記仕事関数が３.０ｅＶ以下の金属が、アルカリ金属、及びアルカリ土類金属からなる群から選択される、上記［１］から［５］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［７］ 前記化合物（Ｂ）が遷移金属酸化物である、上記［１］から［６］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［８］ 前記遷移金属酸化物が、Ｖ、Ｎｂ、Ｔａ、Ｃｒ、Ｍｏ、Ｗ、Ｍｎ、Ｔｃ、及びＲｅからなる群から選ばれる１種類以上の金属の酸化物である、上記［７］に記載の有機エレクトロルミネッセンス素子。
［９］ 前記仕事関数が３．０ｅＶ以下の金属がＬｉであり、前記仕事関数が４．０ｅＶ以上の化合物がＶ₂Ｏ₅である、上記［１］から［８］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［１０］ 前記第１電極が、塗布法により形成される、上記［１］から［９］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［１１］ 前記第１電極が、
光透過性を有する膜本体と、
該膜本体中に配置され、導電性を有するワイヤ状の導電体とを含む、上記［１］から［１０］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［１２］ 前記ワイヤ状の導電体の径が２００ｎｍ以下である、上記［１１］に記載の有機エレクトロルミネッセンス素子。
［１３］ 前記ワイヤ状の導電体が、前記膜本体中において網目構造を構成している、上記［１２］に記載の有機エレクトロルミネッセンス素子。
［１４］ 前記膜本体が、導電性を有する樹脂を含む、上記［１１］から［１３］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［１５］ 前記第１電極が、陽極である、上記［１］から［１４］のいずれか一項に記載の有機エレクトロルミネッセンス素子。
［１６］ 上記［１］から［１５］のいずれか一項に記載の有機エレクトロルミネッセンス素子を備える照明装置。
［１７］ 上記［１］から［１５］のいずれか一項に記載の有機エレクトロルミネッセンス素子を備える面状光源。
［１８］ 上記［１］から［１５］のいずれか一項に記載の有機エレクトロルミネッセンス素子を備える表示装置。 In order to solve the above problems, the present invention employs the following configuration.
[1] a substrate having optical transparency;
A first electrode having one of an anode and a cathode and having light transmissivity provided in contact with the substrate;
A second electrode that is the other of the anode and the cathode;
A plurality of light emitting units provided between the first electrode and the second electrode, each including an organic light emitting layer;
A charge generation layer disposed between the light emitting units,
The charge generation layer includes at least one selected from the group consisting of metals and compounds thereof having a work function of 3.0 eV or less, and at least one compound (B) having a work function of 4.0 eV or more. Including
When the refractive index of the first electrode is n1 and the refractive index of the substrate is n2, n1 and n2 are represented by the following formula (1):

Meet,
Organic electroluminescence device.
[2] The organic electroluminescent element according to the above [1], wherein the light emitting unit includes an organic light emitting layer formed by a coating method.
[3] The organic electroluminescent element according to the above [1] or [2], wherein the organic light emitting layer contains a polymer organic compound.
[4] The charge generation layer comprises a first layer containing one or more selected from the group (A) and a second layer containing one or more of the compound (B), The organic electroluminescence according to any one of [1] to [3], wherein the first layer is disposed closer to the first or second electrode as the anode than the second layer. element.
[5] The charge generation layer is a layer formed by mixing one or more types selected from the group (A) and one or more types of the compound (B). Organic electroluminescent element as described in any one of these.
[6] The organic electroluminescence according to any one of [1] to [5], wherein the metal having a work function of 3.0 eV or less is selected from the group consisting of alkali metals and alkaline earth metals. element.
[7] The organic electroluminescence device according to any one of [1] to [6], wherein the compound (B) is a transition metal oxide.
[8] In the above [7], the transition metal oxide is an oxide of one or more metals selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, and Re. The organic electroluminescent element of description.
[9] The above [1] to [8], wherein the metal having a work function of 3.0 eV or less is Li, and the compound having a work function of 4.0 eV or more is V ₂ O _5. The organic electroluminescent element of description.
[10] The organic electroluminescence element according to any one of [1] to [9], wherein the first electrode is formed by a coating method.
[11] The first electrode is
A film body having optical transparency;
The organic electroluminescence element according to any one of [1] to [10], including a wire-like conductor disposed in the film body and having conductivity.
[12] The organic electroluminescent element according to the above [11], wherein the wire-like conductor has a diameter of 200 nm or less.
[13] The organic electroluminescent element according to the above [12], wherein the wire-like conductor forms a network structure in the film main body.
[14] The organic electroluminescence element according to any one of [11] to [13], wherein the film body includes a resin having conductivity.
[15] The organic electroluminescence element according to any one of [1] to [14], wherein the first electrode is an anode.
[16] An illumination device including the organic electroluminescence element according to any one of [1] to [15].
[17] A planar light source comprising the organic electroluminescence element according to any one of [1] to [15].
[18] A display device comprising the organic electroluminescence element according to any one of [1] to [15].

  According to the present invention, it is possible to realize a multi-photon type organic EL element having high light extraction efficiency, high luminance, and excellent light emission performance. Therefore, the organic EL element of the present invention can be suitably used for display devices such as lighting devices, planar light sources, and flat panel displays.

FIG. 1 is a front cross-sectional view showing a first embodiment of the organic EL element of the present invention. FIG. 2 is a front cross-sectional view showing a second embodiment of the organic EL element of the present invention. FIG. 3 is a front sectional view showing another laminated structure of the light emitting unit of the organic EL element of the present invention. FIG. 4 is a front sectional view showing a configuration of a conventional organic EL element.

  Hereinafter, an embodiment of the organic EL element of the present invention will be described with reference to the drawings. For ease of understanding, the scale of each member in the drawing may differ from the actual scale. The present invention is not limited to the following description, and can be appropriately changed without departing from the gist of the present invention. For convenience of explanation of the layer structure and the like, in the example shown below, the organic EL element will be described together with the figure in which the substrate is placed below. However, the organic EL element of the present invention and the organic EL device equipped with the organic EL element are not necessarily arranged in this manner. It is not manufactured or used. In the following description, one of the support substrate in the thickness direction may be referred to as “upper” or “upper”, and the other of the support substrate in the thickness direction may be referred to as “lower” or “lower”.

を満たすことを特徴としている。
なお本明細書では「光透過性を有する支持基板」、「光透過性を有する電極」は、入射した光の少なくとも一部が透過する支持基板、電極をそれぞれ意味する。 1. Organic EL Device of the Present Invention The organic EL device of the present invention is a light transmissive substrate and one of an anode and a cathode, and a light transmissive first electrode provided in contact with the substrate. An electrode, a second electrode which is the other of the anode and the cathode, a plurality of light emitting units provided between the first electrode and the second electrode, each including an organic light emitting layer, and the light emitting unit A charge generation layer disposed between and at least one selected from the group (A) consisting of a metal having a work function of 3.0 eV or less and a compound thereof, and the work function is When the refractive index of the first electrode is n1 and the refractive index of the substrate is n2, n1 and n2 are represented by the following formula (1):

It is characterized by satisfying.
In the present specification, “light-transmitting support substrate” and “light-transmitting electrode” mean a support substrate and an electrode through which at least part of incident light is transmitted.

The organic EL element of the present embodiment is a multi-photon type organic EL element having a configuration in which a plurality of light emitting units are stacked through a charge generation layer. The layer structure which an organic EL element can take is shown below.
(I) Anode / first light emitting unit / charge generating layer / second light emitting unit / cathode (ii) anode / light emitting unit / (charge generating layer / light emitting unit) x / cathode It represents that the layers sandwiching “/” are stacked adjacent to each other. The symbol “x” represents an integer of 2 or more, and “(charge generation layer / light emitting unit) x” represents that x layers of the layered structure including the charge generation layer and the light emitting unit are stacked. The organic EL element is configured by providing a laminated body (hereinafter, sometimes referred to as a light emitting function unit) having the configuration shown in (i) or (ii) on a support substrate. The light emitting function unit is provided on the support substrate with one of the anode and the cathode disposed near the support substrate.

[First Embodiment]
With reference to FIG. 1, the organic EL element of the first embodiment and a modification thereof will be described. FIG. 1 is a front view showing an organic EL element according to the first embodiment of the present invention.
The organic EL element 10 in the present embodiment includes a light emitting function unit 17 and a support substrate 15 on which the light emitting function unit 17 is mounted.

  The light emitting function unit 17 is usually arranged on the support substrate 15 so that the anode 14 as the first electrode having light transmittance is arranged closest to the support substrate 15 in the configuration of (i) or (ii) described above. Provided. In the present embodiment, the light emitting function unit 17 includes an anode 14 as a first electrode, a first light emitting unit 11, a charge generation layer 13, a second light emitting unit 12, and a cathode 16 as a second electrode. The layers are stacked in this order from the side. Thus, in this embodiment, the multiphoton type organic EL element 10 in which the first and second light emitting units 11 and 12 are stacked via the charge generation layer 13 is configured.

In the present embodiment, in order to protect the light emitting function unit 17, a sealing substrate (also referred to as an upper sealing film) 18 that covers the light emitting function unit 17 is further provided.
In this embodiment, an anode is provided as the first electrode 14, and a cathode is provided as the second electrode 16. However, as a modification, the stacking order of the light emitting function parts 17 is reversed, the cathode is provided as the first electrode, You may comprise the organic EL element which provided the anode as 2 electrodes. Further, in the configuration of (i) or (ii) described above, the light emitting function unit may be provided on the support substrate 15 so that the cathode is disposed closest to the support substrate 15 as the second electrode.

<1. Light emitting function>
As described above, the light emitting function unit 17 includes the anode (first electrode) 14, the cathode (second electrode) 16, the first light emitting unit 11, the second light emitting unit 12, and the first light emitting unit 11 and the second light emitting unit 11. The charge generation layer 13 is provided between the light emitting unit 12 and the light emitting unit 12. Each of the first and second light emitting units 11 and 12 includes an organic light emitting layer. The first light emitting unit 11 is composed of only the first organic light emitting layer 11, and the second light emitting unit 12 is composed of only the second organic light emitting layer.

  First, the first light emitting unit 11, the second light emitting unit 12, the charge generation layer 13, and the first electrode 14 will be described, and then other components of the organic EL element will be described.

<A> Light-emitting unit The light-emitting unit includes an organic light-emitting layer. The light emitting unit includes one or more organic light emitting layers. In addition, the light emitting unit may be comprised only by the organic light emitting layer, and may contain the layer different from an organic light emitting layer. Among the layers constituting the light emitting unit, examples of the layer provided on the anode side with respect to the organic light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. Among the layers constituting the light emitting unit, examples of the layer provided on the cathode side with respect to the organic light emitting layer include an electron injection layer, an electron transport layer, and a hole blocking layer. A layer different from these organic light emitting layers will be described later as an optional layer.
The light emitting unit has the same configuration as a portion sandwiched between an anode and a cathode in a normal organic EL element that is not a multiphoton type, that is, an organic EL element having one organic light emitting layer. In the organic EL element 10 of the present embodiment shown in FIG. 1, the first light emitting unit 11 is composed of only the first organic light emitting layer, and the second light emitting unit 12 is composed of only the second light emitting layer. .

  The organic light emitting layer can be formed by a coating method, a vapor deposition method, or the like, and it is preferable that the light emitting unit includes an organic light emitting layer formed by a coating method. That is, the light emitting unit preferably includes an organic light emitting layer formed by applying a solution containing a material for forming an organic light emitting layer (hereinafter sometimes referred to as a light emitting material) and drying. In the organic EL element 10 of the present embodiment, the first and second organic light emitting layers 11 and 12 are formed by a coating method.

The organic light emitting layer is a layer containing an organic compound as a light emitting material. The organic light emitting layer contains an organic substance (low molecular compound and / or high molecular compound) that mainly emits fluorescence and / or phosphorescence as a light emitting material. In the present specification, the polymer compound has a polystyrene-equivalent number average molecular weight of 10 ³ or more. The upper limit of the number average molecular weight is not particularly limited, but the upper limit of the number average molecular weight in terms of polystyrene is usually 10 ⁸ or less. The organic light emitting layer may further contain a dopant material. Examples of the material for forming the organic light emitting layer include the following dye materials, metal complex materials, polymer materials, and dopant materials.

<A-1> Dye-type material Examples of the dye-type material include cyclopentamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxadiazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, and distyrylarylene derivatives. Pyrrole derivatives, thiophene ring compounds, quinacridone derivatives, coumarin derivatives, pyridine ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxadiazole dimers, pyrazoline dimers, and the like.

<A-2> Metal complex materials As metal complex materials, for example, rare earth metals such as Tb, Eu, Dy, or Al, Zn, Be, Ir, Pt, etc. are used as the central metal, and oxadiazole, thiadiazole. , Phenylpyridine, phenylbenzimidazole, metal complexes having a quinoline structure as a ligand, for example, metal complexes having emission from a triplet excited state such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoins A quinolinol beryllium complex, a benzoxazolyl zinc complex, a benzothiazole zinc complex, an azomethylzinc complex, a porphyrin zinc complex, a phenanthroline europium complex, and the like can be given.

<A-3> Polymer material Examples of polymer materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, Examples include those obtained by polymerizing metal complex light emitting materials.
Among the above 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. it can. Of these, polymer materials such as polyvinyl carbazole 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, and polyfluorene derivatives are preferable.

<A-4> Dopant material A dopant may be added to the light emitting layer for the purpose of improving the light emission efficiency or 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 usually about 2 nm or more and 2000 nm or less.

<A-5> Method for Forming Organic Light-Emitting Layer As a method for forming an organic light-emitting layer, a method of forming a film from a solution, a vacuum deposition method, a transfer method, or the like can be used. The solvent of the solution used in the method of forming a film from a solution is preferably a solvent that dissolves the luminescent material. For example, a chlorine-based solvent such as chloroform, methylene chloride, or dichloroethane, an ether-based solvent such as tetrahydrofuran, toluene, xylene, or the like. Examples thereof include aromatic hydrocarbon solvents, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate, and ethyl cellosolve acetate, and water.

  In the method of forming a film from a solution, as a method of applying the solution on the surface on which the organic light emitting layer is formed, for example, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method , Wire bar coating method, dip coating method, slit coating method, capillary coating method, spray coating method, nozzle coating method and other coating methods, gravure printing method, screen printing method, flexographic printing method, offset printing method, reverse printing method, A coating method such as a printing method such as an inkjet printing 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 an organic light emitting layer only at a desired place by laser or friction transfer or thermal transfer can be used.

<B> Charge generation layer The charge generation layer is sandwiched between the light emitting units. The charge generation layer generates charges (holes and electrons) in a state where a voltage is applied between the pair of electrodes. The generated electrons are injected into the light emitting unit adjacent to the anode side with respect to the charge generation layer, and the generated holes are injected into the light emitting unit adjacent to the cathode side with respect to the charge generation layer. In addition to the charge injected from the pair of electrodes, the charge generated in the charge generation layer is injected into the element. Therefore, by providing the charge generation layer, the light emission efficiency (current efficiency) with respect to the injected current is increased. improves.

  In the present embodiment, the charge generation layer 13 is composed of at least one selected from the group consisting of a metal having a work function of 3.0 eV or less and a compound thereof (A), and a compound (B) having a work function of 4.0 eV or more. Including one or more types. By using one or more compounds (B) in combination, a charge generation layer that efficiently generates charges can be formed as compared with a charge generation layer consisting of only one or more of those selected from the group (A). Can do.

  The work function of the material selected from the group (A) consisting of a metal having a work function of 3.0 eV or less and a compound thereof is preferably 1.5 eV or more. The work function of the compound (B) having a work function of 4.0 eV or more is preferably 7.5 eV or less.

  A metal compound having a work function of 3.0 eV or less refers to a compound having a metal work function of 3.0 eV or less and a work function of the compound itself of 3.0 eV or less. By configuring the charge generation layer containing a material whose work function satisfies such a range, efficient charge injection is likely to occur.

  The metal having a work function of 3.0 eV or less constituting the charge generation layer can be selected from the group consisting of alkali metals, alkaline earth metals, and rare earth metals. Among these, alkali metals and alkaline earth metals are preferable. Examples of alkali metals include lithium (Li) (2.93 eV), sodium (Na) (2.36 eV), potassium (K) (2.28 eV), rubidium (Rb) (2.16 eV), and cesium (Ce). (1.95 eV) is preferable, and as the alkaline earth metal, calcium (Ca) (2.9 eV) and barium (Ba) (2.52 eV) are preferable (the work function is shown in parentheses). Among these, Li is more preferable. Examples of the metal compound having a work function of 3.0 eV or less constituting the charge generation layer include the metal oxides, halides, fluorides, borides, nitrides, carbides, and the like.

As the compound (B) having a work function of 4.0 eV or more, an inorganic or organic compound having a work function of 4.0 eV or more is selected. As the inorganic compound having a work function of 4.0 eV or more, a transition metal oxide is preferable. Among the transition metal oxides, vanadium (V), niobium (Nb), tantalum (Ta), chromium (Cr), molybdenum (Mo ), Tungsten (W), manganese (Mn), technetium (Tc), rhenium (Re), and the like are preferable, and V ₂ O ₅ is more preferable.

  As an organic compound having a work function of 4.0 eV or more, it is difficult to dissolve in a coating solution used in the process after forming the charge generation layer, and it is easy to accept electrons from those selected from the group (A). A material is preferable, and a material that forms a charge transfer complex with a material selected from the group (A) consisting of a metal having a work function of 3.0 eV or less and a compound thereof is more preferable. An example of such a material is tetrafluoro-tetracyanoquinodimethane (4F-TCNQ).

The charge generation layer can have the following two structures.
(I) a first layer 13-1 containing one or more selected from the group (A) consisting of the metal and a compound thereof, and a second layer 13-2 containing one or more of the compound (B) A charge generation layer 13 (laminated structure: see FIG. 1).
(Ii) A charge generation layer (mixed layer) in which at least one selected from the group consisting of the metal and a compound thereof (A) is mixed with at least one of the compounds (B).

  In the case of the laminated structure (i), it is preferable to dispose the first layer 13-1 closer to the anode than the second layer 13-2.

  Note that the charge generation layer (ii) as the mixed layer is formed by a method of forming a layer in which two kinds of materials are mixed at once using a method such as co-evaporation, or by forming the material constituting the first layer very thinly. Thus, an island-like discrete structure before becoming a continuous film can be formed, and a second layer can be formed on this structure to form a mixed layer.

  In order to sufficiently obtain the effects of the present invention, the thickness of the first layer 13-1 is preferably 0.1 nm or more and 10 nm or less, more preferably 0.1 nm or more and 6 nm or less. The thickness of the second layer 13-2 is preferably 2 nm or more and 100 nm or less, more preferably 4 nm or more and 80 nm or less.

  The charge generation layer of this embodiment may further include a transparent conductive thin film as the third layer. As the transparent conductive thin film, indium oxide, zinc oxide, tin oxide, indium tin oxide (ITO), or the like can be used.

  The light transmittance of the charge generation layer of this embodiment preferably has a high transmittance for the light emitted from the organic light emitting layer. In order to sufficiently extract light and obtain sufficient luminance, the transmittance of light having a wavelength of 550 nm is preferably 30% or more, and more preferably 50% or more.

(Mixed color, white)
The light emission color of the organic EL element 10 is a color mixture of light emitted from each light emitting unit. In the present embodiment, since the first and second light emitting units 11 and 12 are included, the light extracted from the organic EL element 10 by color mixture by making the emission wavelengths of the first and second light emitting units 11 and 12 different from each other. Can be different from the color of the light emitted from the first and second light emitting units 11 and 12, respectively. For example, two colors of complementary colors, or three or more light emitting units can be used to produce three colors (RGB, etc.) or four or more colors. Can be white. For example, an organic EL element that emits light with a desired emission color can be realized by making the emission colors of the first organic light emitting layer 11 and the second organic light emitting layer 12 of the present embodiment different from each other. The degree of freedom can be improved.

(Cavity effect)
The layer structure and layer thickness of each light emitting unit are preferably designed in consideration of the cavity effect (light interference effect). Specifically, an integer of ¼ of the value obtained by dividing the wavelength of light generated from the first and second light emitting units 11 and 12 by the average refractive index of the structure sandwiched between the anode 14 and the cathode 16. It is preferable to set the thickness of the structure twice. This is because the light extraction efficiency is maximized by the light interference effect in the configuration satisfying such a relationship. The effect is maximum when this relationship is strictly established, but even if it is not strictly established, the effect is manifested.Therefore, the thickness of the structure is roughly divided by the emission wavelength by the average refractive index. It may be within ± 20% of an integral multiple of 1/4 of the measured value. Further, the distance between the portion that substantially emits light and the reflective electrode (the cathode 16 in this embodiment) that reflects light is an integral multiple of 1/4 of the value obtained by dividing the emission wavelength by the average refractive index. In this case, the light interference effect is maximized. In the plurality of light emitting units, it is preferable that the above relationship is satisfied for all the light emitting units. However, if the above relationship is satisfied for at least one light emitting unit, the cavity effect is manifested. It is preferable to control the layer thickness so that one light emitting unit satisfies the above-described relationship.

<C> 1st electrode A 1st electrode is an electrode of any one of an anode and a cathode, and is an electrode which has a light transmittance. The first electrode 14 in the present embodiment corresponds to the anode 14 of the organic EL element 10.

  The anode 14 in the present embodiment includes a light-transmitting film main body and a wire-like conductor disposed in the film main body and having conductivity. As the film body, one having a high light transmittance in the visible light region is preferably used. The film body is made of a resin, an inorganic polymer, an inorganic-organic hybrid compound, or the like.

  The anode (first electrode) 14 in this embodiment preferably has a light transmittance of 80% or more in the visible light region, a volume resistivity of 1 Ω · cm or less, and a surface roughness Ra of 100 nm or less. The light transmittance, volume resistivity, and surface roughness Ra in the visible light region of the anode 14 can be adjusted by appropriately adjusting the weight ratio, diameter, and density of the conductor disposed in the film body. it can.

The light transmittance in the visible light region decreases as the weight ratio of the wire-like conductor increases. The weight ratio of the conductor having a light transmittance of 80% or more is about 30% or less, although it depends on the material of the film body and the conductor and the diameter of the conductor.
The volume resistivity decreases as the weight ratio of the conductor increases. The weight ratio of the conductor having a volume resistivity of 1 Ωcm or less is 10 ⁻⁵ % or more, depending on the material of the film body and the conductor and the diameter of the conductor, but the volume resistivity is 10 ⁻³ Ωcm or less. The weight ratio of the conductor is 1% or more.
The light transmittance in the visible light region increases as the diameter of the conductor decreases, and increases as the density of the conductor increases.

  As the membrane body, a resin having conductivity is preferably used. Thus, in addition to the wire-like conductor, the membrane main body has conductivity, so that the anode 14 can be reduced in electric resistance (hereinafter, electric resistance may be abbreviated as resistance). By using such a low-resistance anode 14, it is possible to suppress voltage drop at the anode 14, realize low-voltage driving of the organic EL element, and suppress luminance unevenness.

  The film thickness of the anode 14 is appropriately set depending on the electrical resistance, the visible light transmittance, and the like, and is, for example, 0.03 μm or more and 10 μm or less, preferably 0.05 μm or more and 1 μm or less.

<C-1> Wire-like conductor The wire-like conductor preferably has a small diameter. The diameter of the wire-like conductor is preferably 400 nm or less, more preferably 200 nm or less, and even more preferably 100 nm or less. . Since the wire-like conductor diffracts or scatters light passing through the anode 14, the haze value of the anode 14 is increased and the light transmittance is decreased, but the diameter is approximately the wavelength of visible light or smaller than the wavelength of visible light. By using this wire-shaped conductor, the haze value for visible light can be kept low and the light transmittance can be improved. Moreover, since resistance will become high if the diameter of a wire-shaped conductor is too small, 10 nm or more is preferable. Note that when the organic EL element is used in a lighting device, the anode 14 having a high haze value may be preferably used because the haze value of the anode 14 can illuminate a wide range if it is somewhat high. Therefore, the optical characteristics of the anode 14 are appropriately set according to the apparatus in which the organic EL element is used.

  There may be one or more wire-like conductors arranged in the membrane body. The wire-like conductor preferably forms a network structure in the film body. For example, in the membrane body, one or a plurality of wire-like conductors are arranged in an intricately intertwined manner throughout the membrane body to form a network structure. Specifically, a structure in which one wire-like conductor is intertwined in a complicated manner or a plurality of wire-like conductors are arranged in contact with each other spreads two-dimensionally or three-dimensionally to form a mesh. Forming a structure. The wire-shaped conductor may be, for example, curved or needle-shaped. The curved and / or needle-shaped conductors come into contact with each other to form a network structure, whereby the anode 14 having a low volume resistivity can be realized. This network structure may be regular or non-regular. The volume resistivity of the anode 14 can be lowered by the wire-like conductor forming the network structure.

  It is preferable that at least a part of the wire-like conductor is disposed near the surface of the anode 14 opposite to the support substrate 15. By arranging the wire-like conductor in this way, the resistance of the surface portion of the anode 14 can be lowered.

  As a material for the wire-like conductor, for example, a metal having low resistance such as Ag, Au, Cu, Al, and alloys thereof is preferably used. Wire conductors include, for example, the method by NRJana, L. Gearheart and CJMurphy (Chm. Commun., 2001, p617-p618), C. Ducamp-Sanguesa, R. Herrera-Urbina, and M. Figlarz, etc. (J. Solid State Chem., Vol. 100, 1992, p272-p280).

を満たす。
また陽極１４は、発光機能部１７において当該陽極１４に接する部材の屈折率ｎ３以下であることが好ましい。本実施形態において陽極１４に接する部材の屈折率ｎ３は、発光ユニット１１（有機発光層１１）の屈折率に相当する。本実施形態では有機発光層が陽極１４に接して設けられているが、後述するように、正孔注入層、正孔輸送層などが陽極１４に接して設けられる場合もある。有機発光層、正孔注入層および正孔輸送層の屈折率は、それぞれ通常１．５〜１．８程度である。 <C-2> Control of Refractive Index In the organic EL element 10 according to this embodiment, when the refractive index of the anode 14 as the first electrode is n1, and the refractive index of the support substrate 15 is n2, the refractive index of the anode 14 is set. n1 is the following formula (1):

Meet.
The anode 14 preferably has a refractive index n3 or less of a member in contact with the anode 14 in the light emitting function unit 17. In this embodiment, the refractive index n3 of the member in contact with the anode 14 corresponds to the refractive index of the light emitting unit 11 (organic light emitting layer 11). In the present embodiment, the organic light emitting layer is provided in contact with the anode 14. However, as will be described later, a hole injection layer, a hole transport layer, or the like may be provided in contact with the anode 14. The refractive indexes of the organic light emitting layer, the hole injection layer, and the hole transport layer are each usually about 1.5 to 1.8.

  In a conventional bottom emission type organic EL element, an ITO thin film has been used as an anode. The refractive index n1 of the ITO thin film is about 2, the refractive index n2 of the glass substrate is about 1.5, and the refractive index n3 of a member (for example, a hole injection layer) in contact with the ITO thin film is about 1.7. It is. As described above, in the conventional organic EL element, the ITO thin film having a high refractive index is disposed between the glass substrate having a low refractive index and the organic light emitting layer. Since a member with high refractive index (ITO thin film) is interposed in this way, part of the light is reflected on the surface of the ITO thin film due to total reflection and the like, and light from the organic light emitting layer can be efficiently extracted outside. There wasn't.

  On the other hand, in this embodiment, the anode 14 which is the first electrode satisfying the relationship of the above formula (1) is used, and the refractive index of the first organic light emitting layer 11 in contact with the anode 14 is preferably a refractive index n3 or less as a preferred embodiment. Is used. For this reason, compared with the conventional organic EL element, the organic EL element in which the difference of each refractive index of the support substrate 15, the anode 14, and the member (first organic light emitting layer 11) in contact with the anode 14 is small can be configured. . Thereby, it is possible to suppress the light from the first and second organic light emitting layers 11 and 12 from being reflected by the anode 14 and improve the light extraction efficiency. In particular, if the support substrate 15 satisfying the relationship of n2 ≦ n1 ≦ n3 is used, the light from the first and second organic light emitting layers 11 and 12 is further suppressed from being reflected by the anode 14, and the light extraction efficiency is further improved. can do. Thereby, the luminance of the organic EL element can be improved.

  In addition, when the surface roughness Ra of the anode 14 is 100 nm or less, each layer is sequentially formed on the flat anode 14, so that variations in film thickness in each layer can be suppressed. Further, when a thin film is formed on the anode having protrusions formed on the surface by, for example, a coating method, the protrusions may penetrate the thin film and cause a short circuit. However, by suppressing the surface roughness Ra of the anode 14 to 100 nm or less. The occurrence of a short circuit due to the protrusion of the anode 14 can be suppressed.

<C-3> Manufacturing Method of First Electrode A manufacturing method of the anode 14 corresponding to the first electrode will be described. As a method for producing the anode 14, for example, a wire-like conductor is kneaded into a resin to disperse the wire-like conductor in the resin, or the wire-like conductor and the resin are dispersed in a dispersion medium. Examples thereof include a method of forming a film by a coating method using a dispersion, and a method of coating a wire-like conductor on the surface of a resin film and dispersing the conductor in the film. In addition, you may add various additives, such as surfactant and antioxidant, to the anode 14 as needed. The type of resin is appropriately selected according to the characteristics required for the anode 14 such as refractive index, light transmittance, and electrical resistance. Further, the amount of the wire-like conductor dispersed affects the electrical resistance, haze value, translucency and the like of the anode 14, and is appropriately set according to the characteristics required for the anode 14.

  The anode 14 of this embodiment forms a coating film by applying a dispersion liquid in which a conductive wire-like conductor is dispersed in a dispersion medium to the support substrate 15, and further cures the coating film. Obtained by. Since the anode 14 can be formed by the coating method as described above, the anode 14 is formed by using a vacuum apparatus such as vacuum deposition and sputtering, or compared with the case where the anode 14 is formed by a special process. Thus, the anode 14 can be easily formed and the cost can be reduced. Furthermore, since the characteristics of the anode 14 are determined by the types of the resin and the wire-shaped conductor, the shape of the wire-shaped conductor, and the like, the anode showing the intended optical characteristics and electrical characteristics can be selected by appropriately selecting them. 14 can be easily manufactured.

  The dispersion is prepared by dispersing a wire-like conductor and a resin in a dispersion medium. Examples of the dispersion medium used include chlorine-based solvents such as chloroform, methylene chloride and dichloroethane, ether-based solvents such as tetrahydrofuran, aromatic hydrocarbon solvents such as toluene and xylene, ketone-based solvents such as acetone and methyl ethyl ketone, and ethyl acetate. And ester solvents such as butyl acetate and ethyl cellosolve acetate.

  The resin preferably has a high light transmittance. When the layer provided on the anode 14 is formed by a coating method, the resin constituting a part of the anode 14 is dissolved in the coating solution used. It is necessary not to. Examples of such resins include low density or high density polyethylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, and ethylene-norbornene copolymer. Polyolefin resins such as ethylene-dmon copolymer, polypropylene, ethylene-vinyl acetate copolymer, ethylene-methyl methacrylate copolymer, ionomer resin; polyester resins such as polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate; Nylon-6, nylon-6,6, metaxylenediamine-adipic acid condensation polymer; amide resin such as polymethylmethacrylamide; acrylic resin such as polymethylmethacrylate; polystyrene, styrene-acrylic Styrene-acrylonitrile resins such as nitrile copolymers, styrene-acrylonitrile-butadiene copolymers, polyacrylonitrile; hydrophobic cellulose resins such as cellulose triacetate and cellulose diacetate; polyvinyl chloride, polyvinylidene chloride, polyvinylidene fluoride Halogen-containing resins such as polytetrafluoroethylene; hydrogen-bonding resins such as polyvinyl alcohol, ethylene-vinyl alcohol copolymers and cellulose derivatives; polycarbonate resins, polysulfone resins, polyethersulfone resins, polyetheretherketone resins, polyphenylene Examples thereof include engineering plastic resins such as oxide resins, polymethylene oxide resins, polyarylate resins, and liquid crystal resins.

  Moreover, when forming the layer provided on the anode 14 by a coating method, from the viewpoint that the resin constituting a part of the anode 14 is difficult to dissolve in the coating solution used, the thermosetting resin is used as the resin. A photocurable resin or a photoresist material is preferably used.

  Moreover, as resin, the resin which has electroconductivity is used suitably. Examples of the conductive resin include polyaniline and polythiophene derivatives.

  The refractive index of the anode 14 is mainly determined by the refractive index of the film body composed of resin or the like. The refractive index of the film body is mainly determined by, for example, the type of resin used, and therefore the anode 14 having the intended refractive index can be easily formed by appropriately selecting the resin used.

  If a dispersion in which a wire-like conductor is dispersed in a photosensitive material and a photocurable monomer used for a photosensitive photoresist is used, the anode 14 having a predetermined pattern shape can be easily formed by a coating method and photolithography. Can be formed.

  Since the anode 14 is preferably one that does not change at the temperature heated in the step of forming the organic EL element, the resin constituting the anode 14 preferably has a glass transition point Tg of 150 ° C. or higher, and 180 ° C. The above are more preferable, and those of 200 ° C. or higher are more preferable. Examples of such a resin include polyether sulfone having a glass transition point Tg of 230 ° C. and a high heat resistant photoresist material.

  The types of binders and additives mixed in the dispersion liquid as needed, and the dispersion amount of the wire-like conductor are appropriately set and selected according to conditions such as the ease of film formation and the characteristics of the anode 14. be able to.

  As a method of applying the dispersion liquid in which the wire-like conductor is dispersed, dipping method, coating method by bar coater, coating method by spin coater, doctor blade method, spray coating method, screen mesh printing method, brush coating, spraying, roll coating, etc. The methods generally used in the industry can be mentioned. In addition, when using a thermosetting resin and a photocurable resin, after apply | coating a dispersion liquid, a coating film can be hardened by heating or light irradiation.

In the organic EL element of the present embodiment described above, a multi-photon element including the first light emitting unit 11 and the second light emitting unit 12 that emit light simultaneously is configured. By providing a plurality of light emitting units in this way, the amount of light generated inside the organic EL element can be increased. In addition, the light extraction efficiency can be increased as described above when the refractive index n1 of the first electrode 14 and the refractive index n2 of the support substrate 15 each satisfy the above-described formula (1). As described above, by increasing the amount of light generated inside the organic EL element and increasing the light extraction efficiency, it is possible to realize a multi-photon type organic EL element with better light emission performance.
Further, since each of the plurality of light emitting units emits light, the luminance of the organic EL element 10 is obtained by superimposing the light emitted from each light emitting unit. By providing a plurality of light emitting units in this way, the load can be distributed to each light emitting unit. When the organic EL element 10 of this embodiment is driven with the same light amount as a single photon type organic EL element having only one light emitting unit, the load applied to each light emitting unit can be suppressed, so that the lifetime of the element is long. Can be achieved.

を満たすように、導電性を有するワイヤ状の導電体を分散媒に分散させた分散液を、前記基板の表面上に塗布することにより第１電極を形成する工程と、前記第１電極の上に、前記発光ユニットおよび前記電荷発生層を交互に積層する工程と、第２電極を形成する工程とを含む。また、前記電荷発生層は、仕事関数が３．０ｅＶ以下の金属およびその化合物からなる群（Ａ）から選ばれるものの１種類以上と、仕事関数が４．０ｅＶ以上の化合物（Ｂ）の１種類以上とを含むように形成される。 In addition, the organic EL device according to the present embodiment can be manufactured by a manufacturing method according to the following process using the method for manufacturing the first electrode as described above.
That is, a light-transmitting substrate and any one of an anode and a cathode, a light-transmitting first electrode provided in contact with the substrate, and the other electrode of the anode and the cathode A plurality of light emitting units provided between the first electrode and the second electrode and each including an organic light emitting layer, and a charge generation layer disposed between the light emitting units. In the method of manufacturing an organic electroluminescence element, when the refractive index of the first electrode is n1 and the refractive index of the support substrate is n2, n1 and n2 are respectively represented by the following formula (1):

A step of forming a first electrode by applying a dispersion liquid in which a conductive wire-like conductor is dispersed in a dispersion medium so as to satisfy the above conditions; And the step of alternately stacking the light emitting units and the charge generation layer and the step of forming the second electrode. The charge generation layer may be one or more selected from the group (A) consisting of a metal having a work function of 3.0 eV or less and a compound thereof, and one of the compounds (B) having a work function of 4.0 eV or more. It is formed so as to include the above.

  Subsequently, components of the organic EL element other than the first light emitting unit 11, the second light emitting unit 12, the charge generation layer 13, and the first electrode (anode) 14 described above will be described in detail below.

<D> Support Substrate The support substrate 15 is preferably one that does not change in the step of forming the organic EL element, and may be a rigid substrate or a flexible substrate. For example, a glass plate, a plastic plate, a polymer film and a silicon plate, and a laminated plate obtained by laminating these can be used as the support substrate 15. As the support substrate 15, those having an absolute value of the difference in refractive index from the first electrode (anode in this embodiment) 14 having a refractive index of less than 0.4 are used as appropriate.

  In the so-called bottom emission type organic EL element that takes out light from the support substrate 15 side (see FIG. 1), the support substrate 15 having a high light transmittance in the visible light region is preferably used.

<E> Second electrode The second electrode is the other of the anode and the cathode, and is disposed to face the first electrode. The second electrode in the present embodiment is an electrode arranged to face the anode 14 and serves as the cathode 16. As such a cathode material, a material having a small work function and easy electron injection into the light emitting layer is preferable. The cathode material is preferably a material having high electrical conductivity and high visible light reflectance. Examples of such a cathode material include metals, metal oxides, alloys, graphite or graphite intercalation compounds, and inorganic semiconductors such as zinc oxide (ZnO).

  As the metal, an alkali metal, an alkaline earth metal, a transition metal, a group 13 metal of the periodic table, or the like can be used. 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 can be given.

  Examples of the alloy include alloys containing at least one of the above metals. Specifically, magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium -A magnesium alloy, a lithium-indium alloy, a calcium-aluminum alloy, etc. can be mentioned.

  The cathode 16 may be constituted by an electrode having optical transparency as necessary, for example, when light is extracted from the cathode side. Examples of such light-transmitting cathode materials include conductive metal oxides such as indium oxide, zinc oxide, tin oxide, ITO and IZO, and conductive organic materials such as polyaniline or derivatives thereof, polythiophene or derivatives thereof. be able to.

  The cathode 16 may have a laminated structure of two or more layers. In some cases, the electron injection layer is used as a cathode.

  The film thickness of the cathode 16 is appropriately selected in consideration of electrical conductivity and durability, and is, for example, 10 nm or more and 10 μm or less, preferably 20 nm or more and 1 μm or less, more preferably 50 nm or more and 500 nm or less. .

  Examples of the method for forming the cathode 16 include a vacuum deposition method, a sputtering method, and a laminating method in which a metal thin film is thermocompression bonded.

<F> Sealing substrate The cathode 16 was formed in order to protect the light emitting function part 17 composed of “anode 14 / first light emitting unit 11 / charge generation layer 13 / second light emitting unit 12 / cathode 16”. After that, a sealing substrate (upper sealing film) 18 for sealing the light emitting function part 17 is formed. The sealing substrate 18 is composed of an inorganic layer or an organic layer, and usually has one or more inorganic layers and one or more organic layers. The number of laminated layers of the inorganic layer and the organic layer is appropriately determined based on required characteristics. Inorganic layers and organic layers are usually laminated alternately.

  The shape of the sealing substrate 18 is not particularly limited as long as it can seal the light emitting function portion 17 in a state of being bonded to the support substrate 15, and may be a flat plate shape (see FIG. 1) or a flat substrate. You may use the board | substrate of the shape which provided the space which accommodates the light emission function part 17 by forming a counterbore (not shown). In the example shown in FIG. 1, the sealing substrate 18 and the light emitting functional unit 17 are adhered and bonded together. However, when a gap is generated between the sealing substrate 18 and the light emitting functional unit 17, the void is formed. A filler such as a resin may be provided. The sealing substrate 18 may be a rigid substrate or a flexible substrate. For the sealing substrate 18, a member similar to the member exemplified for the support substrate 15 may be used.

  Since the light-emitting substances constituting the first and second organic light-emitting layers 11 and 12 are liable to be deteriorated by contact with gas and liquid, the light-emitting function unit 17 is highly airtight or suppressed in order to suppress deterioration of the element. It is preferable to seal in a watertight manner. Since the plastic substrate has a higher gas and liquid permeability than the glass substrate, when the plastic substrate is used as the support substrate 15, it is preferable to perform a treatment for improving the barrier property against the gas and the liquid on the plastic substrate in advance. . For example, it is preferable to stack a lower sealing film having a high barrier property against gas and liquid on a plastic substrate, and then stack the light emitting function part 17 on the lower sealing film. For example, the lower sealing film is formed in the same manner as the sealing substrate (upper sealing film) 18.

<G> Arbitrary Component Layer FIG. 1 shows an organic EL element 10 in which a first light-emitting unit 11, a second light-emitting unit 12, and a charge generation layer 13 are provided between an anode 14 and a cathode 16. However, the configuration of the organic EL element is not limited to the example shown in FIG. 1, and the first and second light emitting units 11 and 12 include other functional layers and organic light emitting elements in addition to the organic light emitting layer. One or more layers may be provided. In the first and second light emitting units 11 and 12, as a layer (functional layer) provided in addition to the organic light emitting layer, as described above, for example, a hole injection layer, a hole transport layer, an electron block layer, an electron injection A layer, an electron transport layer, a hole blocking layer, and the like.

  Examples of layers that can be provided between the anode 14 and the first organic light-emitting layer 11 and between the charge generation layer 13 and the second organic light-emitting layer 12 include a hole injection layer, a hole transport layer, and an electron blocking layer. Is mentioned. When both the hole injection layer and the hole transport layer are provided between the anode 14 and the first organic light emitting layer 11 and between the charge generation layer 13 and the second organic light emitting layer 12, charge generation A layer in contact with the layer or the anode is referred to as a hole injection layer, and a layer excluding this hole injection layer is referred to as a hole transport layer.

  Examples of layers that can be provided between the first organic light emitting layer 11 and the charge generation layer 13 and between the second organic light emitting layer 12 and the cathode 16 include an electron injection layer, an electron transport layer, a hole blocking layer, and the like. Can be mentioned. When both the electron injection layer and the electron transport layer are provided between the first organic light emitting layer 11 and the charge generation layer 13 and between the second organic light emission layer 12 and the cathode 16, 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 hole injection layer and the electron injection layer are sometimes collectively referred to as a charge injection layer. The hole transport layer and the electron transport layer may be collectively referred to as a charge transport layer. In addition, the electron block layer and the hole block layer may be collectively referred to as a charge block layer.

Hereinafter, an arbitrary functional layer (not shown) will be described.
<G-1> Hole Injection Layer The hole injection layer is a layer having a function of improving the hole injection efficiency from the anode or the charge generation layer. The hole injection layer is formed between the anode 14 and the hole transport layer, between the anode 14 and the first organic light emitting layer 11, between the charge generation layer 13 and the second organic light emitting layer 12, and second. It can be provided between the organic light emitting layer 12 and the hole transport layer.
As the hole injection material constituting the hole injection layer, oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, phenylamine type, starburst type amine type, phthalocyanine type, amorphous carbon, polyaniline, And polythiophene derivatives.

    Examples of the method for forming the hole injection layer include vapor deposition and film formation from a solution containing a hole injection material. The film formation from the solution containing the hole injection material can be performed in the same manner as the method of forming the first and second organic light emitting layers 11 and 12 described above. Specifically, a film is formed by applying a coating solution in which a material for the hole injection layer (hole injection material) is dissolved in a solvent in which the material for the hole injection layer is dissolved by a conventional coating method. Can do.

The film thickness of the hole injection layer varies depending on the material used, and is appropriately set so that the drive voltage, the light emission efficiency, and the like are appropriate. The thickness of the hole injection layer is, for example, 1 nm or more and 1 μm or less, preferably 2 nm or more and 500 nm or less, and more preferably 5 nm or more and 200 nm or less.
<G-2> Hole transport layer The hole transport layer is a layer having a function of improving hole injection from the anode 14, the charge generation layer 13, the hole injection layer or the hole transport layer closer to the anode 14. .
Examples of the material constituting the hole transport layer include N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), 4,4′-bis [ Aromatic amine derivatives such as N- (1-naphthyl) -N-phenylamino] biphenyl (NPB), polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having an aromatic amine group in the side chain or main chain , 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 derivative thereof, or Poly (2,5-thieni Lembinylene) or a derivative thereof is exemplified. Among these, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine group in a side chain or a main chain, polyaniline or a derivative thereof, polythiophene or a derivative thereof, polyarylamine or a derivative thereof, poly ( p-phenylene vinylene) or a derivative thereof, or a polymer hole transport material such as poly (2,5-thienylene vinylene) or a derivative thereof is preferable, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a side chain or a main chain More preferred are polysiloxane derivatives having an aromatic amine group. 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 in the case of a low-molecular hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be exemplified. Examples of the hole transport material include film formation from a solution containing the hole transport material.

  As a film forming method from a solution, the same coating method as described above can be given as a method for forming an organic light emitting layer and a hole injection layer.

  As the polymer binder to be mixed, those that do not extremely inhibit charge transport are preferable, and those that weakly absorb visible light are preferably used. For example, polycarbonate, polyacrylate, polymethyl acrylate, polymethyl methacrylate, polystyrene, poly Examples thereof include vinyl chloride and polysiloxane.

  The film thickness of the hole transport layer varies depending on the material used, and may be selected so that the drive voltage and the light emission efficiency are appropriate. The film 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.

<G-3> Electron block layer The electron block layer is a layer having a function of blocking electron transport. When the hole injection layer and / or the hole transport layer has a function of blocking electron transport, these layers may also serve as an electron blocking layer. The fact that the electron blocking layer has a function of blocking electron transport makes it possible, for example, to produce an element that allows only electron current to flow and confirm the blocking effect by reducing the current value. As an electron block layer, the various materials illustrated as a material of the said positive hole injection layer or a positive hole transport layer, for example can be used.

<G-4> Electron Injection Layer The electron injection layer is a layer having a function of improving the electron injection efficiency from the cathode 16 or the charge generation layer 13. The electron injection layer is formed between the first organic light-emitting layer 11 and the charge generation layer 13, between the electron transport layer and the charge generation layer 13, between the second organic light-emitting layer 12 and the cathode 16, or electron transport. Between the layer and the cathode 16.
Examples of the material constituting the electron injection layer include alkali metals, alkaline earth metals, alloys containing at least one of alkali metals and alkaline earth metals, oxides of alkali metals or alkaline earth metals, halides, carbonic acids. Or a mixture of these substances. Examples of alkali metals, alkali metal oxides, halides, and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride , Rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like. Examples of alkaline earth metals, alkaline earth metal oxides, halides and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, Examples thereof include barium fluoride, strontium oxide, strontium fluoride, and magnesium carbonate. The electron injection layer may be composed of a laminate in which two or more layers are laminated, and examples thereof include LiF / Ca. 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 or more and 1 μm or less.

<G-5> Electron transport layer The electron transport layer is a layer having a function of improving electron injection from the cathode, the charge generation layer, the electron injection layer, or the electron transport layer closer to the cathode. It is a layer having a function of transporting.
As the material constituting the electron transport layer, known materials can be used, such as oxadiazole derivatives, anthraquinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, tetracyanoanthraquinodi. Examples include methane or its derivatives, fluorenone derivatives, diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, or metal complexes of 8-hydroxyquinoline or its derivatives, polyquinoline or its derivatives, polyquinoxaline or its derivatives, polyfluorene or its derivatives, etc. The 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, and polyquinoline are more preferable.

Although there is no restriction | limiting in particular as the film-forming method of an electron carrying layer, In the low molecular electron transport material, the vacuum evaporation method from powder or the method by the film-forming from a solution or a molten state is illustrated. Examples of the polymer electron transport material include a method of film formation from a solution or a molten state. In film formation 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 from the solution include the same film formation method as the method for forming the hole injection layer from the above-described solution.

  The film thickness of the electron transport layer varies depending on the material used, and may be selected so that the drive voltage and the light emission efficiency are appropriate. 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.

<G-6> Hole blocking layer The hole blocking layer is a layer having a function of blocking hole transport. In the case where the electron injection layer and / or the electron transport layer have a function of blocking hole transport, these layers may also serve as the hole blocking layer. The fact that the hole blocking layer has a function of blocking hole transport makes it possible, for example, to produce an element that allows only a hole current to flow, and confirm the blocking effect by reducing the current value.

<H> Layer Configuration of Light Emitting Unit As described above, the light emitting unit can adopt various layer configurations. A specific example of the layer structure that the light emitting unit can take is shown below.
a) Organic light emitting layer b) Hole injection layer / organic light emitting layer c) Organic light emitting layer / electron injection layer d) Hole injection layer / organic light emitting layer / electron injection layer e) Hole injection layer / hole transport layer / Organic light-emitting layer f) Organic light-emitting layer / electron transport layer / electron injection layer g) Hole injection layer / organic light-emitting layer / electron transport layer / electron injection layer h) Hole injection layer / hole transport layer / organic light-emitting layer / Electron injection layer i) Hole injection layer / hole transport layer / organic light emitting layer / electron transport layer / electron injection layer (Here, the symbol “/” indicates that each layer sandwiching the symbol “/” is laminated adjacently) (The same shall apply hereinafter.)
In the above configurations a) to i), the left side is a layer closer to the anode, and the right side is a layer closer to the cathode.

  The plurality of light emitting units included in the organic EL element may have the same layer configuration, or may have different layer configurations. The first and second light emitting units 11 and 12 of the present embodiment shown in FIG. 1 have the configuration a). In the embodiment shown in FIG. 1, an embodiment in which the anode 14 is provided on the support substrate 15 is shown. In this case, in each of the forms a) to i), the layers are arranged on the support substrate 15 in order from the layer shown on the left side (anode side).

  In addition, as an organic EL element of other embodiment, the form which arrange | positions a cathode on a support substrate can also be employ | adopted. In this case, in each of the above forms a) to i), the layers are arranged on the support substrate in order from the layer shown on the right side (cathode side).

[Second Embodiment]
Next, with reference to FIG. 2, the organic EL element of the 2nd Embodiment of this invention is demonstrated. FIG. 2 is a front sectional view showing the organic EL element of the second embodiment. In FIG. 2, members that are the same as those in the first embodiment are denoted by the same reference numerals as in FIG. 1. In the following, overlapping description will be omitted, and differences from the first embodiment will be mainly described.
The organic EL element 10 of the first embodiment is a bottom emission type element that emits light from the first and second light emitting units 11 and 12 to the outside through the anode 14 and the support substrate 15, whereas The organic EL element 20 of the second embodiment is a top emission type element that emits light from the first and second light emitting units 11 and 12 to the outside through the cathode (first electrode) 21 and the sealing substrate 18. is there.
The organic EL element 20 of the present embodiment is configured by laminating a support substrate 15, a light emitting function unit 23, and a sealing substrate 18 in this order. The light emitting function unit 23 is configured by laminating an anode 22, a first light emitting unit 11, a charge generation layer 13, a second light emitting unit 12, and a cathode 21 in this order from the support substrate 15 side.

In the present embodiment, the first electrode having optical transparency corresponds to the cathode 21, and the substrate having optical transparency corresponds to the sealing substrate 18. When the refractive index of the cathode 21 (first electrode) is n1, and the refractive index of the sealing substrate 18 is n2, n1 and n2 satisfy the following formula (1).

  As the cathode 21 in the present embodiment, for example, the one exemplified as the first electrode in the first embodiment can be used. For example, as described above, the cathode 21 is obtained by a coating method using a dispersion liquid in which a conductive wire-like conductor is dispersed in a dispersion medium.

Also in the organic EL element 20 according to the present embodiment, the same operations and effects as those of the organic EL element according to the first embodiment can be obtained. That is, in a multi-photon type organic EL element configured by laminating a plurality of light emitting units including an organic light emitting layer, a load is distributed to each light emitting unit, and light emitted from each light emitting unit is superimposed. Since it is taken out, the amount of light generated inside the organic EL element 20 can be increased.
Moreover, when the refractive index n1 of the 1st electrode 21 and the refractive index n2 of the sealing substrate 18 satisfy | fill said Formula (1), respectively, light extraction efficiency can be made high.
Therefore, even with the organic EL element according to the present embodiment, the multi-photon type organic EL element with better light emission performance can be obtained by increasing the light amount generated inside the organic EL element 20 and increasing the light extraction efficiency. Can be realized.
Further, even if the multi-photon type organic EL element 20 is driven to have the same light amount as the single-photon type organic EL element, the organic EL element 20 is more first than the single-photon type organic EL element. And since it can be made to light-emit in the state which made the load added to the 2nd organic light emitting layers 11 and 12 small, lifetime improvement of an element can be attained. Therefore, also with the organic EL element according to the present embodiment, the amount of light generated inside the organic EL element 20 can be increased, the life of the element can be extended, and the light extraction efficiency can be increased.

2. Apparatus equipped with organic EL element of the present invention The organic EL element of each embodiment of the present invention described above is suitable for a curved or flat illumination device, for example, a planar light source used as a light source of a scanner, or a display device. Can be used.

Examples of the display device including the organic EL element include an active matrix display device, a passive matrix display device, a segment display device, a dot matrix display device, and a liquid crystal display device. The organic EL element is used as a light emitting element constituting each pixel in an active matrix display device, a passive matrix display device, and a dot matrix display device. Moreover, an organic EL element is used as a light emitting element which comprises each segment in a segment display apparatus. The organic EL element is used as a backlight in a dot matrix display device and a liquid crystal display device.
As described above, the organic EL element of the present invention can realize a multi-photon type element having more excellent light emission performance, and thus can be suitably used for lighting devices, planar light sources, display devices, and the like. .

  Hereinafter, although the present invention will be described in more detail based on production examples and comparative examples, the present invention is not limited to the following production examples.

<Verification of luminous efficiency of multi-photon type organic EL elements>
In Production Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4, organic EL elements having a structure in which two light-emitting units are partitioned by one charge generation layer were produced, and the effects thereof were confirmed.

<Preparation Example 1-1> layer of Preparation (Preparation Example 1-1 of the organic EL device having the structure partitioned by a charge generation layer structure: ITO / PEDOT / MEH-PPV / Li / V 2 O 5 / MEH-PPV / Al -Li alloy)
An example of manufacturing an organic EL element in Preparation Example 1-1 will be described with reference to FIG.
In this fabrication example, the first light emitting unit 11 shown in FIG. 1 is composed of a first organic light emitting layer 11a and a hole injection layer 11b. A substrate in which an ITO film (thickness 150 nm) was formed as an anode 14 on a glass substrate 15 corresponding to a support substrate by a sputtering method was prepared. A PEDOT (poly (3,4-ethylenedioxythiophene)) / PSS (polystyrene sulfonic acid) solution manufactured by BYTRON was formed on this substrate to a thickness of 40 nm by spin coating, and heat-treated at 200 ° C. in a nitrogen atmosphere. Thus, a hole injection layer 11b was obtained. As the luminescent material, MEH-PPV (poly (2-methoxy-5- (2′-ethyl-hexyloxy) -para-phenylenevinylene) having a weight average molecular weight of about 200,000 manufactured by Aldrich was used. A 1% by weight toluene solution was prepared, and this was spin-coated on a substrate on which PEDOT / PSS was formed to form a first organic light emitting layer 11a having a thickness of 90 nm. The first organic light emitting layer 11 a is collectively referred to as the first light emitting unit 11.

On top of this, Li (work function: 2.93 eV) and V ₂ O ₅ (vanadium oxide) (work function: 4 eV or more) are sequentially formed with a thickness of 2 nm and 20 nm as the charge generation layer 13 by vacuum deposition. First layer 13-1 and second layer 13-2. Here, the deposition of Li is performed by using an Al-Li alloy (Li content 0.05%) and depositing only Li that flies first for several tens of seconds before Al begins to fly, and immediately after that V ₂ O. Evaporation of ₅ was performed.
Further, a 1 wt% toluene solution of MEH-PPV was spin-coated on the V ₂ O ₅ film to form a second organic light emitting layer (second light emitting unit) 12 with a film thickness of 90 nm. Further, an Al—Li alloy having a thickness of 100 nm was formed thereon as a cathode 16 by vacuum evaporation. Thus, an organic EL element having a structure in which two light emitting units were separated by one charge generation layer was produced.
When a DC voltage was applied to the obtained device, the light emission starting voltage was 12 V and the maximum luminance was 80 cd / m ² . The current efficiency was 0.072 cd / A, which was increased 1.95 times compared to the element (0.037 cd / A) of Comparative Example 1-1 below.

<Comparative Example 1-1> Preparation of organic EL element (layer structure of Comparative Example 1-1: ITO / PEDOT / MEH-PPV / Al-Li alloy)
For comparison, FIG. 4 shows the same procedure as in Preparation Example 1-1 except that the charge generation layer 13 and the second organic light-emitting layer (second light-emitting unit) 12 are not provided in Preparation Example 1-1. As shown, an organic EL element 40 having only one light emitting unit 11 was produced. In FIG. 4, the same members as those in FIG.
Upon application of a direct current voltage to the organic EL element 40 of the comparative example 1-1, light emission start voltage 5.5V, and a maximum luminance 52 cd / m ^2. The current efficiency was 0.037 cd / A.

<Comparative Example 1-2> Preparation of Organic EL element (the layer structure of Comparative Example 1-2: ITO / PEDOT / MEH- PPV / V 2 O 5 / MEH-PPV / Al-Li alloy)
An organic EL device was produced in the same manner as in Comparative Example 1-1 except that the charge generation layer was composed of only one layer of V ₂ O _{5 having} a thickness of 30 nm. Even when 40 V was applied to the resulting device, no light was emitted.

Layer structure of <Preparation Example 1-2> different color mixing element obtained by laminating a light-emitting unit (Preparation Example 1-2: ITO / PEDOT / F8- TPA-BT / Li / V 2 O 5 / PEDOT / PSS / F8- TPA-PDA / Al-Li alloy)
Instead of MEH-PPV used as the light emitting material in Production Example 1-1, a polymer light emitting material 31 (abbreviated as F8 (poly (9,9-dioctylfluorene)) represented by the following structural formula (1) that emits green light. After forming the first light emitting unit 11 including the polymer light emitting layer using -TPA (triphenylamine) -BT (polybisamide triazole)) as the light emitting material and the charge generation layer 13, the PEDOT / PSS layer is formed. A polymer light-emitting layer using a polymer light-emitting material 32 (abbreviated as F8-TPA-PDA (p-phenylenediamine)) represented by the following structural formula (2), which is formed and subsequently emits blue light, as a light-emitting material is included. After the second light-emitting unit 12 was formed, a cathode was formed in the same manner as in Production Example 1-1, and light-emitting elements having different emission wavelengths from the two light-emitting units were manufactured.

Polymer light emitting material 31

Polymer light emitting material 32

<Comparative Examples 1-3, 1-4> Comparison of Production Example 2, single element consisting of only green and blue light-emitting layers (layer configuration of Comparative Example 1-3: ITO / PEDOT / F8-TPA-BT / Al -Li alloy)
(Layer structure of Comparative Example 1-4: ITO / PEDOT / F8-TPA-PDA / Al-Li alloy)
For comparison with Preparation Example 1-2, an element composed of one light-emitting unit having a structure of ITO / PEDOT / organic light-emitting layer / Al—Li alloy was prepared as in Comparative Example 1-2. Here, in Comparative Example 1-3, F8-TPA-BT that emits green light is used as the light emitting material for the organic light emitting layer, and in Comparative Example 1-4, F8-TPA-PDA that emits blue light is used as the organic light emitting material. Used for layer.

  The driving voltages of Comparative Examples 1-3 and 1-4 are 3.6 V and 5.4 V, respectively, whereas in Manufacturing Example 1-2, the driving voltage is 8.0 V, which is close to the expected voltage of an element in which two units are stacked. Indicated. Further, in the element of Preparation Example 1-2, the spectrum was widened and whited green light emission was obtained due to the color mixture from the two layers.

  Next, in the following production examples 2-1 to 2-3, the refractive index of the first electrode in which the wire-like conductor is provided in the light-transmitting film main body is controlled within a specific range, and the transparent support It is confirmed that the light extraction efficiency can be improved by controlling the refractive index difference between the substrate and the first electrode within a specific range.

<Preparation Example 2-1> Preparation of organic EL element in which wire-like conductor is installed in first electrode As wire-like conductor, amino group-containing polymer dispersant (made by IC Japan Ltd.) Silver nanowires (major axis average length 1 μm, minor axis average length 10 nm) whose surface is protected by a trade name “Solsperse 24000SC”) are used. 2 g of toluene dispersion of silver nanowire (containing 1.0 g of silver nanowire) and trimethylolpropane triacrylate (made by Shin-Nakamura Chemical Co., Ltd., trade name “NK Ester-TMPT”) which is a photocurable monomer serving as the film body 0.25 g is mixed, the silver nanowires are dispersed in the mixed solution, and 0.0025 g of a polymerization initiator (trade name “Irgacure 907” manufactured by Ciba-Geigy Corporation of Japan) is added. This mixed solution is applied to a 0.7 mm thick glass substrate (transparent plate body: refractive index: about 1.5), heated on a hot plate at 110 ° C. for 20 minutes to dry the solvent, and further irradiated with a UV lamp. (6000 mW / cm ² ) to obtain a transparent conductive film having a thickness of 150 nm. By forming the film in this way, a transparent conductive film having a transmittance of 80% or more and a volume resistivity of 1 Ω · cm or less can be obtained.

  The refractive index of the photo-curing resin is 1.47, and the refractive index of the obtained transparent conductive film is also 1.47. The transparent plate with the transparent conductive film is used as a transparent supporting substrate having a first electrode having light transmittance or An organic EL element can be obtained by using it for a transparent sealing substrate. In the obtained organic EL element, the light extraction efficiency is improved.

<Preparation Example 2-2> Preparation of organic EL device in which wire-like conductor is installed in first electrode As wire-like conductor, amino group-containing polymer dispersant (manufactured by IC Japan Ltd.) Silver nanowires (major axis average length 1 μm, minor axis average length 10 nm) whose surface is protected by a trade name “Solsperse 24000SC”) are used. 1. 2 g of this silver nanowire in toluene dispersion (containing 1.0 g of silver nanowire) and a poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution (trade name “BaytronP” manufactured by Starck Co., Ltd.) to be the membrane body. 5 g is mixed and silver nanowires are dispersed in the mixed solution. This mixed solution is applied to a glass substrate (transparent plate body) having a thickness of 0.7 mm, heated on a hot plate at 200 ° C. for 20 minutes, and dried to obtain a transparent conductive film having a thickness of 150 nm. By forming the film in this way, a transparent conductive film having a transmittance of 80% or more and a volume resistivity of 1 Ω · cm or less can be obtained.

  "BaytronP" has a refractive index of 1.7, and the resulting transparent conductive film also has a refractive index of 1.7. The transparent plate with the transparent conductive film is used as a transparent support substrate having a first electrode having optical transparency or An organic EL element can be obtained by using it for a transparent sealing substrate. In the obtained organic EL element, the light extraction efficiency is improved.

<Preparation Example 2-3> Preparation of organic EL device in which wire-like conductor is installed in first electrode As wire-like conductor, amino group-containing polymer dispersant (made by IC Japan Ltd.) Silver nanowires (major axis average length 1 μm, minor axis average length 10 nm) whose surface is protected by a trade name “Solsperse 24000SC”) are used. A mixture of poly (ethylenedioxythiophene) / polystyrene sulfonic acid solution (trade name “BaytronP”, manufactured by Starck Co., Ltd.) 2.5 g mixed with 0.125 g of dimethyl sulfoxide, and silver nanowire toluene 2 g of dispersion liquid (containing 1.0 g of silver nanowires) is mixed, and the silver nanowires are dispersed in the mixed solution. This mixed solution is applied to a 0.7 mm thick glass substrate, heated at 200 ° C. for 20 minutes on a hot plate, and dried to obtain a conductive film having a thickness of 150 nm. By forming the film in this way, a transparent conductive film having a transmittance of 80% or more and a volume resistivity of 1 Ω · cm or less is obtained.

  The refractive index of “BaytronP” is 1.7, and the refractive index of the obtained transparent conductive film is 1.7. The transparent plate with the transparent conductive film is used as a transparent support substrate or a transparent sealing substrate having a transparent first electrode. An organic EL element can be obtained by using for this. In the obtained organic EL element, the light extraction efficiency is improved.

10, 20, 30 Organic EL element 11, 11a First light emitting unit (first organic light emitting layer)
12 Second light emitting unit (second organic light emitting layer)
13 Charge Generation Layer 13-1 First Layer 13-2 Second Layer 14 Anode (First Electrode)
15 Support substrate 16 Cathode (second electrode)
17, 23 Laminate (light emitting function part)
18 Sealing substrate (upper sealing film)
21 Cathode (first electrode)
22 Anode (second electrode)

Claims (18)

A substrate having optical transparency;
A first electrode having one of an anode and a cathode and having light transmissivity provided in contact with the substrate;
A second electrode that is the other of the anode and the cathode;
A plurality of light emitting units provided between the first electrode and the second electrode, each including an organic light emitting layer;
A charge generation layer disposed between the light emitting units,
The charge generation layer includes at least one selected from the group consisting of metals and compounds thereof having a work function of 3.0 eV or less, and at least one compound (B) having a work function of 4.0 eV or more. Including
When the refractive index of the first electrode is n1 and the refractive index of the substrate is n2, n1 and n2 are represented by the following formula (1):

Meet,
Organic electroluminescence device.   The organic electroluminescent element according to claim 1, wherein the light emitting unit includes an organic light emitting layer formed by a coating method.   The organic electroluminescent element according to claim 1, wherein the organic light emitting layer contains a polymer organic compound.   The charge generation layer comprises a first layer containing one or more selected from the group (A), and a second layer containing one or more of the compound (B), the first The organic electroluminescent element according to claim 1, wherein the layer is disposed closer to the first or second electrode as the anode than the second layer.   4. The charge generation layer according to claim 1, wherein the charge generation layer is a layer formed by mixing one or more types selected from the group (A) and one or more types of the compound (B). 5. The organic electroluminescent element of description.   The organic electroluminescent element according to any one of claims 1 to 5, wherein the metal having a work function of 3.0 eV or less is selected from the group consisting of an alkali metal and an alkaline earth metal.   The organic electroluminescent element according to any one of claims 1 to 6, wherein the compound (B) is a transition metal oxide.   The organic electro according to claim 7, wherein the transition metal oxide is an oxide of one or more metals selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, and Re. Luminescence element. Wherein a work function less metal 3.0eV is Li, the work function of more than 4.0eV compound is V ₂ O _5, the organic electroluminescent device according to any one of claims 1 8 .   The organic electroluminescent element according to any one of claims 1 to 9, wherein the first electrode is formed by a coating method. The first electrode is
A film body having optical transparency;
The organic electroluminescent element according to claim 1, wherein the organic electroluminescent element includes a wire-like conductor disposed in the film main body and having conductivity.   The organic electroluminescent element according to claim 11, wherein a diameter of the wire-like conductor is 200 nm or less.   The organic electroluminescent element according to claim 12, wherein the wire-like conductor forms a network structure in the film main body.   The organic electroluminescent element according to claim 11, wherein the film main body includes a conductive resin.   The organic electroluminescent element according to claim 1, wherein the first electrode is an anode.   An illuminating device provided with the organic electroluminescent element as described in any one of Claims 1-15.   A planar light source comprising the organic electroluminescence element according to any one of claims 1 to 15.   A display apparatus provided with the organic electroluminescent element as described in any one of Claims 1-15.

Images