Organic electroluminescent element, and its manufacturing method

The present invention relates to an organic electroluminescent device, a method for manufacturing the same, a lighting device, a planar light source, and a display device.

The organic EL element is configured to include a pair of electrodes and a light emitting layer (hereinafter, may be referred to as an organic light emitting layer) containing an organic compound provided between the electrodes. When a voltage is applied to the organic EL element, holes are injected from the anode and electrons are injected from the cathode, and these holes and electrons are recombined in the organic light emitting layer to emit light. An organic EL element is usually configured to include one organic light emitting layer, but in order to improve the luminous efficiency with respect to an injected current, an organic EL element having a configuration in which a plurality of light emitting units including an organic light emitting layer are stacked is provided. Proposed. Such an organic EL device is provided with a charge generation layer between light emitting units (see, for example, Patent Document 1).

In the organic EL element, one of the pair of electrodes is used as a transparent electrode, and the light radiated from the organic light emitting layer is taken out from the transparent electrode side. However, most of the light generated inside the organic EL device is not effectively used because it is trapped inside the device due to total internal reflection at the electrodes and internal light absorption. ..

If the light extraction efficiency is low, the luminous efficiency of the entire element is low as a result. Therefore, for example, a light scattering layer is provided between the transparent substrate on which the organic EL element is provided and the electrode of the organic EL element to totally reflect the light. (For example, see Patent Document 2).

<patcit num="1"><text>Japanese Unexamined Patent Publication No. 2003-272860</text></patcit><patcit num="2"><text>JP-A-2007-035550</text></patcit>

<p> As described above, attempts have been made to improve the organic EL device from various viewpoints in order to improve the luminous efficiency, but further improvement of the luminous efficiency is required.</p><p> The present invention has been made in view of the above-mentioned problems in the prior art, and the problems thereof are a multiphoton type organic EL element having high light extraction efficiency and superior luminous efficiency, a manufacturing method thereof, and a lighting device. , To provide a planar light source and a display device.</p>

<p>In order to solve the above problems, the following configuration was adopted in the present invention. [1] An electrode that is either an anode or a cathode and has a light-transmitting first electrode. A second electrode, which is arranged to face the first electrode and is 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 having a light emitting layer containing an organic compound, The charge generation layer sandwiched between the light emitting units and A film arranged on the outermost layer on the first electrode side with reference to the light emitting unit is provided. The charge generation layer includes one or more of those 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 or more of a compound (B) having a work function of 4.0 eV or more. , The surface of the film opposite to the light emitting unit side is uneven, the haze value is 70% or more, and the total light transmittance is 80% or more. Organic electroluminescence element. [2] The organic electroluminescence device according to the above [1], wherein the light emitting layer contains a polymer organic compound. [3] The charge generating layer includes a first layer containing one or more of those selected from the group (A) composed of the metal or a compound thereof, and a second layer containing one or more of the compound (B). The organic electroluminescence device according to the above [1] or [2], wherein the first layer is arranged closer to the anode than the second layer. [4] The charge generating layer is a layer formed by mixing one or more of those selected from the group (A) composed of the metal or a compound thereof and one or more of the compounds (B). The organic electroluminescent device according to 1] or [2]. [5] The organic electroluminescence element according to any one of the above [1] to [4], 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. .. [6] The organic electroluminescence device according to any one of the above [1] to [5], wherein the compound (B) is a transition metal oxide. [7] The organic according to the above [6], wherein the transition metal oxide is an oxide of one or more kinds of metals selected from the group consisting of V, Nb, Ta, Cr, Mo, W, Mn, Tc, and Re. Electroluminescence element. [8] A metal having a work function of 3.0 eV or less is Li, and a compound having a work function of 4.0 eV or more is V.₂O₅The organic electroluminescence device according to any one of the above [1] to [7]. [9] The organic electroluminescence device according to any one of the above [1] to [8], wherein the surface of the film opposite to the light emitting unit side is provided with a plurality of recesses. [10] An electrode of either an anode or a cathode, which is a first electrode having light transmission and an electrode of the other of the anode and the cathode, which is arranged to face the first electrode. A second electrode, a plurality of light emitting units provided between the first electrode and the second electrode, each having a light emitting layer containing an organic compound, and a charge generating layer sandwiched between the light emitting units. A method for manufacturing an organic electroluminescence element including a film arranged on the outermost layer on the first electrode side with reference to the light emitting unit. A step of forming the first electrode, a step of forming the second electrode, a step of forming a plurality of light emitting units between the first and second electrodes, and a step of forming a charge generation layer between the light emitting units. The film installation step of providing the film having a surface opposite to the light emitting unit side having an uneven surface, a haze value of 70% or more, and a total light transmittance of 80% or more in the outermost layer is included. In the film installation step, a solution containing the material to be the film is applied onto the surface to be formed on which the film is formed so that the thickness of the film is in the range of 100 μm to 200 μm, and the applied solution is applied. A method for manufacturing an organic electroluminescent element, which is dried and formed into a film after keeping the humidity in an atmosphere of 80% to 90%. [11] A lighting device including the organic electroluminescence element according to any one of the above [1] to [9]. [12] A planar light source including the organic electroluminescence element according to any one of the above [1] to [9]. [13] A display device including the organic electroluminescence element according to any one of the above [1] to [9].</p>

<p> According to the present invention, a multi-photon type organic EL device in which light emitting units provided with an organic light emitting layer are stacked in a plurality of stages is configured, and a top emission type organic EL is used by using a second electrode composed of a specific three layers. The element can be configured. In the multiphoton type organic EL element, each light emitting unit shares and emits the light extracted as the whole element, and as a result, the load applied to the entire organic EL element can be dispersed to each light emitting unit. .. Therefore, when a single photon type organic EL element consisting of only one organic light emitting layer and a multi-photon type organic EL element are driven under the same brightness conditions, the organic light emitting layer of the single photon type organic EL element becomes available. The load applied to each organic light emitting layer of the multiphoton type organic EL element can be lightened as compared with the applied load. As described above, the multi-photon type organic EL device can reduce the load applied to each organic light emitting layer, so that the life of the device can be extended. On the outermost layer of such a multiphoton type organic EL element, a film having an uneven surface on the side opposite to the light emitting unit side, a haze value of 70% or more, and a total light transmittance of 80% or more is provided. As a result, the light extraction efficiency can be increased. As a result, it is possible to realize a multiphoton type organic EL element having high luminous efficiency (ratio of light taken out to the outside with respect to the electric power input to the organic EL element). Furthermore, by improving the light extraction efficiency, it is possible to suppress the amount of light that should be generated inside the organic EL element, and as a result, the load on the organic EL element can be reduced, so that multiphotons with better light emission can be achieved. A type of organic EL element can be realized. Therefore, the organic EL element of the present invention can be suitably used as a display device such as a lighting device, a planar light source, and a flat panel display.</p>

Hereinafter, embodiments 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. Further, the present invention is not limited to the following description, and can be appropriately modified without departing from the gist of the present invention. In an organic EL device equipped with an organic EL element, there are members such as electrode lead wires, but the description is omitted because they are not directly required in the description of the present invention. For convenience of explanation of the layer structure and the like, in the example shown below, the description is given together with the figure in which the substrate is arranged below, but the organic EL element of the present invention and the organic EL device on which the substrate is mounted are not necessarily manufactured in this arrangement. Or it is not used. In the following description, one of the support substrates in the thickness direction may be referred to as an upper or upper position, and the other in the thickness direction of the support substrate may be referred to as a lower or lower position.

1. Organic EL device of the present invention The organic EL element according to the present invention is an electrode of either an anode or a cathode, and is arranged so as to face the first electrode having light transmission and the first electrode, and among the anode and the cathode. A second electrode, which is the other electrode of the above, and a plurality of light emitting units provided between the first electrode and the second electrode, each of which contains an organic light emitting layer, and a charge generation unit sandwiched between the light emitting units. A group (A) comprising a layer and a film arranged on the outermost layer on the first electrode side with respect to the light emitting unit, and the charge generating layer is composed of a metal having a work function of 3.0 eV or less and a compound thereof (A). ) And one or more of the compound (B) having a work function of 4.0 eV or more, and the film has an uneven surface on the side opposite to the light emitting unit side and has a haze. It is characterized in that the value is 70% or more and the total light transmittance is 80% or more.

The organic EL element is a multiphoton type organic EL element including two or more light emitting units, in which a plurality of light emitting units are laminated in a plurality of stages via a charge generation layer. The element configurations that the organic EL element can take are shown below. (i) Anode / first light emitting unit / charge generation layer / second light emitting unit / cathode (ii) Anode / light emitting unit / (charge generation layer / light emitting unit) x / cathode Here, the symbol "/" indicates that the layers sandwiching the symbol "/" are laminated adjacent to each other. Further, the symbol "x" represents an integer of 2 or more, and "(charge generation layer / light emitting unit) x" means that the laminate composed of the charge generation layer and the light emitting unit is laminated in x stages.

[First Embodiment] A first embodiment of the organic EL device and a modified example thereof will be described with reference to FIG. FIG. 1 is a front view showing a first embodiment of the organic EL device of the present invention. The organic EL element 10 in the present embodiment includes two light emitting units, a first light emitting unit 11 and a second light emitting unit 12, each including an organic light emitting layer, and the first light emitting unit 11 and the second light emitting unit 12 A charge generation layer 13 sandwiched between the light emitting units 12 is provided. The first light emitting unit 11 is composed of a first organic light emitting layer 11a and a hole injection layer 11b. The second light emitting unit 12 is composed of only the second organic light emitting layer. The organic EL element 10 is usually provided on the support substrate 15 so that the anode 14 is arranged closest to the support substrate 15 as the first electrode having light transmission in the configuration (i) or (ii) described above. Be done. Further, the support substrate 15 has a first main surface 15a and a second main surface 15b, and is a light emitting functional unit including an anode 14, a first light emitting unit 11, a charge generation layer 13, a second light emitting unit 12, and a cathode 16. 17 is configured to be laminated on the support substrate 15 in this order from the side closer to the first main surface 15a. As described above, in the present embodiment, the multiphoton type element 10 having a configuration in which the first light emitting unit 11 and the second light emitting unit 12 are laminated via the charge generation layer 13 is configured.

Further, in order to protect the light emitting function unit 17, a sealing substrate (sometimes referred to as an upper sealing film) 18 that protects the entire light emitting function unit 17 is usually provided. Further, the organic EL element 10 is provided with a film 19 on the outermost layer on the anode 14 side with reference to the first light emitting unit 11 and the second light emitting unit 12, and in the present embodiment, the second main surface 15b of the support substrate 15 is provided. A film 19 is provided on the surface. That is, the support substrate 15 is interposed between the anode 14 and the film 19, the light emitting function portion 17 is arranged on the first main surface 15a side, and the film 19 is provided in contact with the second main surface 15b side. .. The outermost layer referred to here refers to the outermost layer on the anode 14 side with reference to the first light emitting unit 11 and the second light emitting unit 12 among the elements constituting the organic EL element 10. Well, in this embodiment, the film 19 is the outermost layer. Further, in the present specification, the light-transmitting support substrate and the light-transmitting electrode mean a support substrate and an electrode through which at least a part of incident light is transmitted, respectively.

In the present embodiment, the first electrode 14 having light transmission is the anode and the second electrode 16 is the cathode, but the first electrode having light transmission is obtained by reversing the stacking order of the light emitting function unit 17. The present invention can be suitably applied to an organic EL element in which is a cathode and the second electrode is an anode.

&lt;Light emitting function unit including multiple light emitting units&gt; As described above, the light emitting function unit 17 including the first light emitting unit 11 and the second light emitting unit 12 includes an anode (first electrode) 14, a cathode (second electrode) 16, a first light emitting unit 11, and a second light emitting unit 12. The light emitting unit 12 and the charge generation layer 13 located between the first light emitting unit 11 and the second light emitting unit 12 are provided.

First, the first light emitting unit 11, the second light emitting unit 12, the charge generation layer 13, and the film 19 will be described below. Then, other components of the organic EL element will be described.

&lt;A&gt; Light emitting unit The light emitting unit includes an organic light emitting layer. Further, the light emitting unit may be composed of one organic light emitting layer or may be composed of a plurality of organic light emitting layers. Further, the light emitting unit may be composed of only an organic light emitting layer, or may include an inorganic layer. The light emitting unit has a configuration similar to that of a non-multiphoton type organic EL device, that is, an organic EL device having one organic light emitting layer, sandwiched between an anode and a cathode. In the organic EL element 10 shown in FIG. 1, the first light emitting unit 11 is composed of the first organic light emitting layer 11a and the hole injection layer 11b, and the second light emitting unit 12 has only the second organic light emitting layer. It is composed of.

Further, the light emitting unit may include at least one organic light emitting layer formed by applying a solution containing a material forming a light emitting layer (hereinafter, may be referred to as a light emitting material) and drying the unit. In the organic EL element 10 shown in FIG. 1, the first organic light emitting layer 11a and the second organic light emitting layer 12 may be formed by applying a solution containing a light emitting material and drying it. Further, although the first light emitting unit 11 and the second light emitting unit 12 include only one first organic light emitting layer 11a and the second organic light emitting layer 12, respectively, the first light emitting unit 11 and the second light emitting unit 12 are made to have a plurality of organic light emitting layers. You may.

The light emitting layer is a layer containing a light emitting material, and the organic light emitting layer is a layer containing an organic compound as a light emitting material. The organic light emitting layer mainly contains an organic substance (low molecular weight compound and / or high molecular weight compound) that emits fluorescence and / or phosphorescence. Low molecular weight compounds and high molecular weight compounds used as organic compounds that emit fluorescence and / or phosphorescence are used as light emitting materials. In the present specification, the polymer compound has a polystyrene-equivalent number average molecular weight of 10.³That is all. Regarding the present invention, there is no particular reason to specify the upper limit of the number average molecular weight, but usually, the upper limit of the polystyrene-equivalent number average molecular weight is 10.⁸It is as follows. Further, the organic light emitting layer may further contain a dopant material. Examples of the material for forming the light emitting layer that can be used in the present invention include the following pigment-based materials, metal complex-based materials, polymer-based materials, and dopant materials.

&lt;A-1&gt; Dye-based material Examples of the dye-based material include cyclopendamine derivatives, tetraphenylbutadiene derivative compounds, triphenylamine derivatives, oxaziazole derivatives, pyrazoloquinoline derivatives, distyrylbenzene derivatives, distyrylarylene derivatives, pyrrole derivatives, and thiophene ring compounds. , Pylin ring compounds, perinone derivatives, perylene derivatives, oligothiophene derivatives, oxaziazole dimers, pyrazoline dimers, quinacridone derivatives, coumarin derivatives and the like.

&lt;A-2&gt; Metal complex material Examples of the metal complex material include metal complexes that emit light from a triple-term excited state such as an iridium complex and a platinum complex, aluminum quinolinol complexes, benzoquinolinol berylium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, and azomethyl. Examples thereof include a zinc complex, a porphyrin zinc complex, and a europium complex. Furthermore, as another example of the metal complex material, the central metal has a rare earth metal such as Al, Zn, Be or Tb, Eu, Dy, and the ligand is oxadiazole, thiadiazole, phenylpyridine, phenylbenzo. Examples thereof include metal complexes having an imidazole structure and a quinoline structure.

&lt;A-3&gt; Polymer-based materials Examples of the polymer-based material include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized dyes and metal complex-based luminescent materials. Examples include those that have been used. Among the above-mentioned luminescent materials, examples of the material that emits blue light include dystilyl arylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, polyfluorene derivatives, and the like. it can. Of these, polyvinylcarbazole derivatives, polyparaphenylene derivatives, polyfluorene derivatives and the like, which are polymer materials, are preferable. Examples of the material that emits green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polyparaphenylene vinylene derivatives and polyfluorene derivatives, which are polymer materials, are preferable. Examples of the material that emits red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Of these, polyparaphenylene vinylene derivatives, polythiophene derivatives, polyfluorene derivatives and the like, which are polymer materials, are preferable.

&lt;A-4&gt; Dopant material Dopants may be added to the light emitting layer for the purpose of improving the light emitting efficiency and changing the light emitting 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, and phenoxazone. The thickness of such a light emitting layer is usually about 2 nm or more and 2000 nm or less.

&lt;A-5&gt; Method of forming a light emitting layer As a method for forming the light emitting layer, a method of applying a solution containing a light emitting material on a base layer on which an organic light emitting layer is laminated, a vacuum vapor deposition method, a transfer method, or the like can be used. The solvent used for film formation from the solution may be any solvent that dissolves the luminescent material that mainly constitutes the light emitting layer. For example, water, a chlorine-based solvent such as chloroform, methylene chloride, dichloroethane, or ether such as tetrahydrofuran. Examples thereof include based solvents, aromatic hydrocarbon solvents such as toluene and xylene, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate and ethyl cell solve acetate.

Examples of the method of applying the solution containing the light emitting material on the base layer on which the organic light emitting layer is laminated include a spin coating method, a casting method, a microgravure coating method, a gravure coating method, a bar coating method, a roll coating method, and a 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, inkjet printing. A coating method such as a printing method such as a method can be used. Printing methods such as a gravure printing method, a screen printing method, a flexo printing method, an offset printing method, a reverse printing method, and an inkjet printing method are preferable in that pattern formation and multicolor color coding are easy. Further, in the case of a sublimable low molecular weight compound, a vacuum vapor deposition method can be used. Furthermore, a method of forming an organic light emitting layer only where desired by laser or friction transfer or thermal transfer can also be used.

Further, the light emitting unit may have a layer other than the organic light emitting layer, if necessary. Among the layers constituting the light emitting unit, examples of the layer provided on the anode side with reference to the organic light emitting layer include a hole injection layer, a hole transport layer, and an electron block layer. Further, among the layers constituting the light emitting unit, examples of the layer provided on the cathode side with reference to the organic light emitting layer include an electron injection layer, an electron transport layer, and a hole block layer. These hole injection layer, hole transport layer, electron block layer, electron injection layer, electron transport layer, and hole block layer will be described later as arbitrary layers.

&lt;B&gt; Charge generation layer The charge generation layer is arranged so as to be sandwiched between the light emitting units. When a voltage is applied to the anode and the cathode, the charge generation layer generates charges (holes and electrons), injects electrons into the light emitting unit adjacent to the anode side with respect to the charge generation layer, and generates charges. It functions as a layer for injecting holes into the light emitting unit adjacent to the cathode side of the layer. Luminous efficiency (current efficiency) with respect to the injected current is improved by adding the charge generated in the charge generation layer to the charges injected from the anode and the cathode. In the organic EL element 10 of the present embodiment, as shown in FIG. 1, the charge generation layer 13 is sandwiched between the first light emitting unit 11 and the second light emitting unit 12, and the first light emitting unit 11 and the second light emitting unit 12 are sandwiched between the first light emitting unit 11 and the second light emitting unit 12. It partitions the light emitting unit 12 of 2. As a result, a multi-photon type organic EL element is constructed. In the multi-photon type organic EL element, in the multi-photon type organic EL element, the load is distributed to each light emitting unit, and the light emitted from each light emitting unit is superposed to be extracted. Therefore, the organic EL element of the present embodiment, which is a multi-photon type in which a single photon type organic EL element composed of only one organic light emitting layer and a first light emitting unit 11 and a second light emitting unit 12 are laminated. When the intensity of the light extracted from 10 is the same and compared, the multi-photon type organic EL element 10 has the first organic light emitting layer 11a and the second organic light emitting more than the single photon type organic EL element. The first organic light emitting layer 11a and the second organic light emitting layer 12 can emit light in a state where the power applied to the layer 12 is reduced, and the multiphoton type organic EL element 10 as a whole is a single photon type organic EL element. The amount of light can be the same as. Therefore, even if the multi-photon type organic EL element 10 as a whole is driven so as to have the same amount of light as the single photon type organic EL element, the organic EL element 10 of the present embodiment is a single photon type organic EL. Since the light can be emitted in a state where the load applied to the first organic light emitting layer 11a and the second organic light emitting layer 12 is smaller than that of the element, the life of the device can be extended.

The charge generation layer 13 in the present embodiment is 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 type of a compound (B) having a work function of 4.0 eV or more. Including the above. The charge generation layer 13 is one of the compounds (B) having a work function of 4.0 eV or more, rather than using one or more of those selected from the group (A) consisting of metals having a work function of 3.0 eV or less and their compounds alone. When used in combination with more than one type, electric charges can be generated efficiently.

Although the work function is selected from the group (A) consisting of metals having a work function of 3.0 eV or less and compounds thereof, 3.0 eV is preferable as the upper limit value of the work function, and 1.5 eV is preferable as the lower limit value. Further, the lower limit value of the work function of the compound (B) having a work function of 4.0 eV or more is preferably 4.0 eV, and the upper limit value is preferably 7.5 eV.

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 the work function of the compound itself being 3.0 eV or less. If the charge generation layer 13 does not contain a material whose work function satisfies the above range, effective charge injection is less likely to occur and the effects of the present invention cannot be sufficiently obtained, which is not preferable.

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. Of these, alkali metals and alkaline earth metals are preferable. Alkali metals include lithium (Li) (2.93eV), sodium (Na) (2.36eV), potassium (K) (2.28eV), rubidium (Rb) (2.16eV), and cesium (Ce) (1.95eV). As the alkaline earth metal, calcium (Ca) (2.9eV) and barium (Ba) (2.52eV) are preferable (work functions are shown in parentheses). Of these, Li is more preferred. Examples of the metal compound having a work function of 3.0 eV or less constituting the charge generation layer include oxides, halides, fluorides, borides, nitrides, and carbides of the metals.

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. Transition metal oxides are desirable as inorganic compounds with a work function of 4.0 eV or higher. , Tungsten (W), Manganese (Mn), Technetium (Tc), Renium (Re) and other oxides are preferred, V₂O₅Is more preferable.

As an organic compound having a work function of 4.0 eV or more, electrons are selected from a group (A) consisting of a metal having a work function of 3.0 eV or less and a compound thereof, which is difficult to dissolve in a coating liquid used in a later step. Those exhibiting electron acceptability that are easily received are preferable, and those having a work function of 3.0 eV or less selected from the group (A) consisting of metals and compounds thereof and those forming a charge transfer complex are preferable. Examples of such materials include tetrafluoro-tetracyanoquinodimethane (4F-TCNQ).

The charge generation layer can have the following two structures. (i) The first layer 13-1 in which the charge generation layer 13 contains at least one selected from the group (A) composed of the metal and its compound, and the second layer 13 containing one or more of the compound (B). Includes layers 13-2 and (laminated structure: see Figure 1). (ii) The charge generation layer is a mixed layer containing one or more of those selected from the group (A) composed of the metal and its compound and one or more of the compound (B) in one layer (mixing). layer).

In the case of the laminated structure, as shown in FIG. 1, it is preferable to arrange the first layer 13-1 closer to the anode than the second layer 13-2.

In the case of the mixed layer, a continuous film can be formed by forming a layer in which two kinds of materials are mixed at a time by a method such as co-evaporation, or by forming an extremely thin material constituting the first layer. A mixed layer can be formed by forming a discrete island-like structure before forming a mixed layer and forming a second layer on the structure to form a mixed layer.

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 in order to sufficiently obtain the effects of the present invention. 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.

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

It is desirable that the light transmittance of the charge generation layer of the present embodiment has a high transmittance with respect to the light emitted from the organic light emitting layer. In order to sufficiently extract light and obtain sufficient brightness, the transmittance of light at a wavelength of 550 nm is preferably 30% or more, more preferably 50% or more.

According to the organic EL element 10 of the present embodiment, a single photon type organic EL element including a first light emitting unit 11 and a second light emitting unit 12 that emit light at the same time and having only one organic light emitting layer and a first And when the intensity of the light extracted from the multi-photon type organic EL element 10 in which the second light emitting units 11 and 12 are laminated is compared, the multi-photon type organic EL element 10 is the single photon type. The amount of light applied to the first and second organic light emitting layers 11a and 12 is smaller than that of the organic EL element of the above, and the light intensity of the multiphoton type organic EL element 10 as a whole is the same as that of the single photon type organic EL element. can do. Therefore, even if the multi-photon type organic EL element 10 as a whole is driven so as to have the same amount of light as the single photon type organic EL element, the organic EL element 10 is the first than the single photon type organic EL element. Since the light can be emitted in a state where the load applied to the second organic light emitting layers 11a and 12 is reduced, the life of the device can be extended. As a result, a highly reliable organic EL element can be realized.

(Mixed color, white) Further, since the organic EL element 10 of the present embodiment includes the first light emitting unit 11 and the second light emitting unit 12 that emit light at the same time, the first organic light emitting layer 11a and the second light emitting unit of the first light emitting unit 11 are emitted. By making the emission wavelengths of the second organic light emitting layer 12 of the unit 12 different from each other, the color of the light extracted from the organic EL element 10 by the color mixing is changed to the first light emitting unit 11 and the second light emitting unit 12. It is possible to make the color different from the color of the light emitted from each. For example, the color of the extracted light can be white by combining two colors that are complementary colors, mixing three colors such as RGB, or mixing four or more colors. For example, by making the emission colors of the first organic light emitting layer 11a and the second organic light emitting layer 12 of the present embodiment different from each other, it is possible to realize an organic EL element that emits light with the desired emission color. The degree of freedom in design can be improved.

(Cavity effect) The order and number of layers to be laminated and the thickness of each layer can be appropriately used in consideration of luminous efficiency and device life, but it is preferable to consider the cavity effect (light interference effect). Specifically, the thickness of the structure sandwiched between the anode 14 and the cathode 16 is the wavelength of the light generated from the first light emitting unit 11 and the second light emitting unit 12 by the average refractive index of the structure. It is preferably an integral multiple of 1/4 of the divided value. This is because in a configuration in which such a relationship is satisfied, the light extraction efficiency is maximized due to the light interference effect. The effect is maximized when this relationship is strictly established, but the effect is recognized even if there is an error, and the thickness of the structure is generally 1/4 of the value obtained by dividing the emission wavelength by the average refractive index. It may be within ± 20% of an integral multiple of. Furthermore, the distance between the part that is substantially emitting light and the reflective electrode (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, which is preferable. When the organic EL element 10 is composed of a plurality of light emitting units having different emission colors, it is preferable to control the film thickness so that the above relationship holds for any one wavelength. Alternatively, the layer thickness may be controlled so that the relationship between the layer thicknesses holds for two wavelengths at the same time.

&lt;C&gt; Film The film is provided on the outermost layer on the anode side with reference to the organic light emitting layer. In the organic EL element 10 of the present embodiment, as shown in FIG. 1, the surface of the film 19 on the second main surface 15b side is flat, and the first light emitting unit 11 and the second light emitting unit 12 side. The surface on the opposite side of the film 19 has an uneven shape, the haze value of the film 19 is 70% or more, and the total light transmittance of the film 19 is 80% or more.

FIG. 4 schematically shows a cross section of the film. In FIG. 4, the surface portion of the film on which the uneven shape is formed is on the upper side. As shown in FIG. 4, a plurality of convex portions 19a are formed on the surface portion of the film 19 on the side opposite to the first light emitting unit 11 and the second light emitting unit 12 side, and recesses are formed in the recesses between the convex portions 19a. 19b is formed.

The film 19 is provided on the outermost layer by bonding the flat surface 19c to the second main surface 15b of the support substrate 15. The film 19 is attached to the support substrate 15 using a binder such as a thermosetting resin, a photocurable resin, an adhesive, and an adhesive. When a thermosetting resin is used, the film 19 is bonded to the support substrate 15 and then heated at a predetermined temperature to bond the film 19 to the support substrate 15. When a photocurable resin is used, the film 19 is bonded to the support substrate 15 and then the film 19 is adhered to the support substrate 15 by, for example, irradiating the film 19 with ultraviolet rays. When the film 19 is directly formed on the support substrate 15 or when the bonding agent is provided in advance on the film 19, the bonding agent may not be used.

When an air layer is formed between the film 19 and the support substrate 15, reflection occurs at the interface of the air layer, so that the film is prevented from forming an air layer between the film 19 and the support substrate 15. It is preferable to perform 19 bonding. The maximum refractive index and the minimum refractive index of the refractive index of the film 19, the refractive index of the binder, and the refractive index of the layer to which the film 19 is bonded (support substrate 15 in this embodiment). The smaller the difference, the more preferable it is because the reflection on the bonded surface can be suppressed. Specifically, the difference is preferably 0.2 or less, and more preferably 0.1 or less.

The film 19 of the present embodiment is opposite to the first light emitting unit 11 and the second light emitting unit 12 side after the film 19 is attached to the outer surface of the support substrate 15 (after the film 19 is attached to the outer surface of the support substrate 15). The surface on the side) is formed in an uneven shape, the haze value is 70% or more, and the total light transmittance is 80% or more. If the haze value is less than 70%, a sufficient light scattering effect may not be obtained, and if the total light transmittance is less than 80%, sufficient light may not be extracted. When a thin film 19 is used for an organic EL element, sufficient light extraction efficiency may not be achieved. Therefore, by using the film 19 having a haze value of 70% or more and a total light transmittance of 80% or more, an organic EL device having high light extraction efficiency can be realized. The haze value is expressed by the following formula. Haze value (cloud value) = (diffusion transmittance (%) / total light transmittance (%)) x 100 (%). The diffuse transmittance means the ratio of the diffusely transmitted radiant flux or the luminous flux to the radiant flux or the luminous flux incident on the object, and the haze value is JIS K. It can be measured by the method described in 7136 "Plastic-How to determine the haze of a transparent material". The total light transmittance can be measured by the method described in JIS K 7361-1 Plastic-Test method for total light transmittance of transparent material.

If the size (width) of the convex portion 19a or the concave portion 19b in the width direction perpendicular to the thickness direction of the film 19 is too large, the brightness on the surface of the film 19 becomes non-uniform, and if it is too small, the film 19 is produced. Since the cost is high, it is preferably 0.5 μm to 20 μm, and more preferably 1 μm to 2 μm. The height of the convex portion 19a or the concave portion 19b in the thickness direction of the film 19 is determined by the size (width) of the convex portion 19a or the concave portion 19b in the width direction and the period in which the concave-convex shape is formed. The size (width) or less of the concave portion 19b or the convex portion 19a in the width direction, or the period or less at which the uneven shape is formed is preferable, and it is 0.25 μm or more and 10 μm or less, preferably 0.5 μm or more and 1.0 μm or less.

The shape of the convex portion 19a or the concave portion 19b is not particularly limited, but one having a curved surface is preferable, and for example, a hemispherical shape is preferable. A schematic view of the cross section of the film 19 at this time is shown in FIG. In FIG. 5, the surface portion of the film on which the uneven shape is formed is on the upper side. As shown in FIG. 5, a plurality of recesses 19e are provided on the surface 19d of the film 19 opposite to the first light emitting unit 11 and the second light emitting unit 12 side. That is, the surface 19d, which is a smooth surface of the film 19, becomes a convex portion, and the recess formed between the convex portions 19d becomes a concave portion 19e.

Further, the convex portions 19a and 19d or the concave portions 19b and 19e are preferably arranged regularly, for example, preferably arranged in a grid pattern. Further, on the surface of the film 19, the area of the region where the convex portions 19a and 19d and the concave portions 19b and 19e are formed is preferably 60% or more of the area of the surface of the film 19.

The material constituting the film 19 may be any material that can satisfy the above-mentioned haze value and total light transmittance when molded into the film 19, and is not particularly limited. As the material constituting the film 19, for example, a polymer material and glass may be used. Examples of the polymer material constituting the film 19 include polyarylate, polycarbonate, polycycloolefin, polyethylene naphthalate, polyethylene sulfonic acid, and polyethylene terephthalate. Further, the film 19 is a support made of, for example, the polymer material and glass, and a thin film formed on the surface of the support and having a surface opposite to the surface in contact with the support having an uneven shape. It may be composed of a laminate. The thickness of the film 19 is not particularly limited, but if it is too thin, it will be difficult to handle, and if it is too thick, the total light transmittance will be low. Therefore, it is preferably 20 μm or more and 1000 μm or less.

&lt;C-1&gt; Film forming method Next, a method of forming the film 19 will be described. In the film 19 of the present embodiment, a solution containing a material to be the film 19 is applied on the surface of the base on which the film 19 is laminated so that the thickness of the film 19 is in the range of 100 μm to 200 μm. It is produced by a step of forming a film 19 by drying a solution applied on the surface of a table after maintaining an atmosphere of 80% to 90% humidity and forming a film. The size of the uneven shape formed on the surface is about the same as or larger than the wavelength of light, and is preferably 0.1 μm or more and 100 μm or less.

In the film 19 made of an inorganic material such as glass, for example, a protective film obtained by curing a photoresist is formed in advance in a region where an uneven shape is not formed, and an uneven surface is formed by chemical etching or vapor phase etching. Can be done. Further, in the film 19 made of a polymer material, a method of transferring the uneven surface of the metal plate by pressing the metal plate having an uneven surface against the heated film, and using a roll having an uneven surface, the polymer sheet. Alternatively, a method of rolling a film, a method of extruding a polymer sheet from a slit having an uneven shape, and a method of dropping a solution or dispersion containing a polymer material onto a base having an uneven surface (hereinafter referred to as casting). There is a method of forming a film by forming a film, a method of selectively photopolymerizing a part of the film after forming a film composed of a monomer, and removing the unpolymerized portion, based on a polymer solution under high humidity conditions. An uneven surface can be formed by casting on a table and transferring the water droplet structure to the surface. In the present specification, examples of the base include the above-mentioned substrate made of the polymer material and glass.

Among these methods, for the polymer material, a method of casting the polymer solution on the base and transferring the water droplet structure to the surface under high humidity conditions is preferably used because of the ease of production. This method is a known structure-building method that applies the dissipation process, which is a type of self-organization (see, for example, G. Widawski, M. Rawiso, B. Francois, Nature, p.369-p.387 (1994)). ).

First, the polymer material to be film 19 described above is dissolved in a solvent to prepare a solution for film 19. Examples of the solvent include dichloromethane, chloroform and the like. As the solution for film 19, a solution having a high viscosity is preferable. The solution for film 19 preferably has a high concentration of the polymer material to be film 19, and preferably has a concentration of the polymer material to be film 19 with respect to the solution of 10 wt% or more. Further, in order to improve the size and uniformity of the shape of the uneven shape, a small amount of a surfactant such as a nonionic surfactant may be added to the solution for the film 19.

Next, a coating step of applying a solution containing the material to be the film 19 is performed on one surface of the base base on which the film 19 is formed. Specifically, the prepared solution for film 19 is cast on one surface of the base under high humidity to form a liquid film composed of the solution for film 19. Examples of the base include a support substrate 15 made of a polymer material, glass, or the like, which will be described later.

Next, a film forming step is performed in which the liquid film applied on one surface of the base is kept in an atmosphere of 80% or more and 90% or less in humidity, and then dried to form a film. When the liquid film is left under high humidity, the water vapor in the atmosphere is liquefied and a plurality of droplets are formed on the surface of the liquid film. The droplets are substantially spherical and are formed discretely on the surface of the liquid film. The diameter of the droplets formed on the surface of the liquid film increases with the passage of time due to the further liquefaction of water vapor, and about half of the droplets sink into the liquid film due to their own weight. Further, since the solvent in the liquid film evaporates with the passage of time, the shape of the droplet is transferred to the film 19 at the time of drying.

The film 19 formed in this way is provided with a plurality of concave surfaces on the surface and is formed in a concavo-convex shape. Specifically, a plurality of hemispherical depressions having a diameter of 1 μm or more and 100 μm or less are formed on the surface of the film 19.

By holding the film 19 in a humidity range of 80% or more and 90% or less, a hemispherical depression may be formed on the surface, and then the film may be dried in a lower humidity atmosphere, or 80%. As mentioned above, the film may be dried by holding the film for a long time in the range of 90% or less.

In the method for producing the film 19 described above, the application of the solution for the film 19 is controlled so that the film thickness of the film 19 becomes a predetermined value, and the humidity at the time of drying the liquid film is adjusted. The haze value of the film 19 to be produced can be controlled. Specifically, the film thickness at the start of drying is controlled so that the film thickness of the film 19 formed through the film forming step becomes a predetermined film thickness within the range of 100 μm or more and 200 μm or less. By controlling the humidity so that it becomes a predetermined humidity within the range of 80% or more and 90% or less, it is possible to form a film 19 having a haze value of 70% or more and showing an desired haze value. it can.

The haze value of the film 19 can be controlled by controlling the humidity and the film thickness of the liquid film according to the concentration of the polymer material that becomes the film 19 in the solution when the humidity and the film thickness are changed. This is because the time until the surface dries changes, which changes the size of the concave-convex shape and the density of the concave surface to be formed, and the humidity is used to construct the structure of the concave surface to be formed, such as improving the regularity of the arrangement of the concave surface. It is presumed that this is because it has a great influence. The film thickness of the produced film 19 can be controlled by adjusting the film thickness of the liquid film at the start of drying. Further, since the time until the surface of the liquid film dries changes depending on the evaporation rate of the solvent, the boiling point of the solvent, and the like, the haze value of the film 19 can be controlled by changing the solvent used.

By such a method, a large-area film 19 exhibiting the intended optical properties can be easily produced with simple control and at low cost.

It is also possible to form the film 19 directly on the support substrate 15 by casting the solution for the film 19 on the surface of the support substrate 15.

Like the organic EL element 10 of the present embodiment, the film 19 is arranged on the outermost surface of the organic EL element on the light extraction side, and the film 19 is formed with the first light emitting unit 11 and the second light emitting unit 12 side. Since the surface on the opposite side is formed in a concavo-convex shape, at least a part of the outermost surface on the light extraction side of the organic EL element is formed in a concavo-convex shape. Therefore, a part of the light generated from the first organic light emitting layer 11a and the second organic light emitting layer 12 of the first light emitting unit 11 and the second light emitting unit 12 is incident on the film 19 and has an uneven shape. It is diffracted by the formed surface and emitted into an atmosphere such as air. When the surface of the film 19 opposite to the first light emitting unit 11 and the second light emitting unit 12 side is a flat surface, the first light emitting unit 11 and the second light emitting unit are caused by the total reflection generated on the surface of the organic EL element. Most of the light generated in the first organic light emitting layer 11a and the second organic light emitting layer 12 of 12 is not taken out. On the other hand, by forming the surface on the side from which light is taken out in a concavo-convex shape, the angle of incidence on the outermost surface can be changed, and total reflection can be suppressed by utilizing the diffraction effect to efficiently produce light. Can be taken out. In particular, since a film having a haze value of 70% or more and a total light transmittance of 80% or more is provided, it is possible to improve the light extraction efficiency and realize an organic EL device having high luminous efficiency.

Further, since a plurality of concave surfaces are provided on the surface of the film 19 on the side opposite to the side of the first light emitting unit 11 and the second light emitting unit 12, these concave surfaces exhibit a function similar to that of a concave lens. By providing such a film 19, the radiation angle of the light emitted from the organic EL element can be widened.

Further, the film 19 used for the organic EL element 10 of the present embodiment has a coating step of applying a solution containing a material to be the film 19 on one surface of a predetermined base and a coating process of drying the applied liquid film. It is formed by a film forming step of forming a film. In particular, after applying a solution containing the material to be the film 19 so that the thickness of the film 19 after the film forming step is 100 μm or more and 200 μm or less, and further maintaining the humidity in the range of 80% or more and 90% or less. By drying and forming a film, the surface is formed into an uneven shape, and a film 19 having a haze value of 70% or more and a total light transmittance of 80% or more can be produced. Therefore, for example, the amount of solution applied and the humidity can be adjusted. The film 19 having the intended optical characteristics can be easily manufactured by the simple control of the film 19.

Then, the film 19 is attached to the surface of the support substrate 15 on the side opposite to the first light emitting unit 11 and the second light emitting unit 12 side.

As described above, since the film 19 used for the organic EL element can be easily produced by simple control, the organic EL element having high light extraction efficiency can be easily produced.

As another embodiment, a form in which the cathode 16 as the second electrode is formed on the surface of the substrate can be mentioned, and the cathode 16, the first light emitting unit 11, the charge generation layer 13, and the first are formed on the substrate. In a top-emission organic EL device in which the light emitting unit 12 of 2 and the anode 14 as the first electrode are arranged in this order, for example, it is opposite to the side of the first light emitting unit 11 and the second light emitting unit 12 of the anode 14. A film 19 is provided on the side surface.

According to the organic EL element of the present embodiment described above, a single photon type organic EL element including a first light emitting unit 11 and a second light emitting unit 12 that emit light at the same time and having only one organic light emitting layer. When comparing the multi-photon type organic EL element 10 in which the first and second light emitting units 11 and 12 are laminated with the same intensity of light extracted from the multi-photon type organic EL element 10, the multi-photon type organic EL element 10 is single. Light is emitted in a state where the power applied to the first and second organic light emitting layers 11a and 12 is smaller than that of the photon type organic EL element, and the multi-photon type organic EL element 10 as a whole is the same as the single photon type organic EL element. It can be the amount of light. Therefore, even if the multi-photon type organic EL element 10 as a whole is driven so as to have the same amount of light as the single photon type organic EL element, the organic EL element 10 is the first than the single photon type organic EL element. Since the light can be emitted in a state where the load applied to the second organic light emitting layers 11a and 12 is reduced, the life of the device can be extended. As a result, a highly reliable organic EL element can be realized. Further, a film 19 is provided on the outermost layer on the anode 14 side based on the first and second light emitting units 11 and 12, and the surface opposite to the first and second light emitting units 11 and 12 is made uneven. Since the haze value is 70% or more and the total light transmittance is 80% or more, the light extraction efficiency can be increased. Therefore, according to this embodiment, it is possible to realize a multiphoton type organic EL device having better light emission performance by extending the life of the device and increasing the light extraction efficiency. Therefore, the organic EL element of the present invention can be suitably used as a planar light source as a light source such as a lighting device, a backlight and a scanner, and a display device such as a flat panel display.

The organic EL element 10 according to the present embodiment is manufactured by a manufacturing method by the following steps using the manufacturing method of the light emitting unit as described above and the manufacturing method of the film 19. That is, the method for manufacturing an organic EL element of the present embodiment is an electrode of either an anode or a cathode, which is arranged so as to face the first electrode having light transmission and the first electrode, and the anode. A second electrode, which is the other electrode of the cathode, and a plurality of light emitting units provided between the first electrode and the second electrode and each having a light emitting layer containing an organic compound, and sandwiched between the light emitting units. A method for manufacturing an organic electroluminescence element, comprising: a charge generation layer arranged so as to be arranged and a film arranged on the outermost layer on the first electrode side with reference to the light emitting unit, wherein the first electrode is used. The step of forming, the step of forming the second electrode, the step of forming a plurality of light emitting units between the first and second electrodes, the step of forming a charge generation layer between the light emitting units, and the light emitting unit side. The film forming step includes a film forming step of forming the film having an uneven surface on the opposite side, a haze value of 70% or more, and a total light transmittance of 80% or more in the outermost layer. A solution containing the material to be the film is applied onto the surface to be formed on which the film is formed so that the thickness of the film is in the range of 100 μm to 200 μm, and the applied solution has a humidity of 80%. After maintaining in an atmosphere of ~ 90%, it is dried and formed into a film.

Subsequently, the 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 film 19 will be described in detail below.

&lt;D&gt; Support board The support substrate 15 may be a rigid substrate or a flexible substrate as long as it does not change in the process of forming the organic EL element or does not change when the light emitting function portion 17 is formed. For example, a glass plate or a plastic. Plates, polymer films, silicon plates, and laminated plates obtained by laminating them are preferably used. Further, it is also possible to use a plastic, a polymer film or the like which has been subjected to a low water permeability treatment. As the support substrate 15, a commercially available one can be used. Further, the support substrate 15 can also be manufactured by a known method.

In the so-called bottom emission type organic EL element that extracts the light from the first light emitting unit 11 and the second light emitting unit 12 from the support substrate 15 side as shown in FIG. 1, the support substrate 15 is the light in the visible light region. Those having high transmittance are preferably used. In the top emission type organic EL element that extracts the light from the first light emitting unit 11 and the second light emitting unit 12 from the cathode 16 side as shown in the second embodiment described later, the support substrate is transparent. It may be opaque or opaque.

&lt;E&gt; 1st electrode The first electrode is one of an anode and a cathode, and is a light-transmitting electrode. The first electrode in the present embodiment is transparent having light transmittance for transmitting light from the first organic light emitting layer 11a and the second organic light emitting layer 12 of the first light emitting unit 11 and the second light emitting unit 12. It is an electrode and serves as an anode 14 of the organic EL element 10 of the present embodiment. For the anode 14, a metal oxide having high electrical conductivity, a metal sulfide, or a thin film of metal can be used, and one having high transmittance can be preferably used, and the first organic light emitting layer 11a and the second organic It can be appropriately selected and used according to the constituent material of the light emitting layer 12. Further, as will be described later, an organic EL device having a configuration in which a first electrode having light transmission is used as a cathode is also possible.

Examples of the material of the anode 14 include indium oxide, zinc oxide, tin oxide, ITO (Indium Tin Oxide), IZO (Indium Zinc Oxide), gold, platinum, silver, copper and the like. Thin film is used. Of these, ITO, IZO, and tin oxide are preferable.

Further, as a constituent material of the anode 14, a transparent conductive film of an organic substance such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used.

From the viewpoint of facilitating charge injection into the first light emitting unit 11, conductive polymers such as phthalocyanine derivative and polythiophene derivative, Mo oxide, etc. are placed on the surface of the anode 14 on the side of the first light emitting unit 11. A layer having an average thickness of 1 nm or more and 200 nm or less, such as amorphous carbon, carbon fluoride, or a polyamine compound, or a layer having an average thickness of 10 nm or less made of a metal oxide, a metal fluoride, an organic insulating material, or the like may be provided.

The film thickness of such an anode 14 can be appropriately selected in consideration of light transmission and electrical conductivity, and is, for example, 5 nm or more and 10 μm or less, preferably 10 nm or more and 1 μm or less, and more. It is preferably 20 nm or more and 500 nm or less.

Examples of the method for forming the anode 14 include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Further, as a method of partitioning the anode 14 into a plurality of electrically separated cells, for example, a method of forming a pattern by an etching method using a photoresist after forming a first electrode can be mentioned.

&lt;F&gt; 2nd electrode The second electrode is arranged to face the first electrode and is the other electrode of the anode and the cathode. The second electrode in the present embodiment is an electrode arranged to face the anode 14 and serves as the cathode 16 of the organic EL element 10 of the present embodiment. As the material of such a cathode, a material having a small work function and easy electron injection into an organic light emitting layer is preferable. Further, as the material of the cathode, a material having high electrical conductivity and high visible light reflectance is preferable. Specific examples of such a cathode material include metals, metal oxides, alloys, graphite or graphite interlayer compounds, and inorganic semiconductors such as zinc oxide (ZnO). An organic EL device having a configuration in which the second electrode is used as an anode is also possible.

As the metal, an alkali metal, an alkaline earth metal, a transition metal, a group 13 metal in 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, etc. Examples thereof include scandium, vanadium, zinc, ytterbium, indium, cerium, samarium, europium, terbium, ytterbium and the like.

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, and lithium. -Magnesium alloys, lithium-indium alloys, calcium-aluminum alloys and the like can be mentioned.

The cathode 16 is an electrode having light transmission as needed, such as when light is taken out from the cathode side. Examples of the material of the cathode having such light transmittance include conductive metal oxides such as indium oxide, zinc oxide, tin oxide, ITO and IZO, polyaniline or its derivatives, and conductive organic substances such as polythiophene or its derivatives. be able to.

The cathode 16 may have a laminated structure of two or more layers. The electron injection layer may also be used as a cathode.

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

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

&lt;G&gt; Sealed substrate After the cathode 16 is formed as described above, the light emitting function unit 17 having the anode 14-first light emitting unit 11-charge generation layer 13-second light emitting unit 12-cathode 16 as a basic structure is protected. Therefore, a sealing substrate (upper sealing film) 18 for sealing the light emitting function portion 17 is formed. The sealing substrate 18 usually has at least one inorganic layer and at least one organic layer. The number of layers is determined as needed, and basically, the inorganic layers and the organic layers are alternately laminated.

The shape of the sealing substrate 18 may be a box shape or a flat plate shape as shown in FIG. 1 as long as it can be bonded to the support substrate 15 to seal the light emitting function portion 17. May be (not shown). In the example shown in FIG. 1, there is no gap between the sealing substrate 18 and the light emitting function unit 17, but when there is a gap between the sealing substrate 18 and the light emitting function unit 17, this A filler such as resin may be provided in the voids. The sealing substrate 18 may be a rigid substrate or a flexible substrate. Further, as the sealing substrate 18, the same one as the example illustrated for the support substrate 15 may be adopted.

The plastic substrate has higher gas and liquid permeability than the glass substrate, and the first organic light emitting layer 11a and the second organic light emitting layer constituting the first light emitting unit 11 and the second light emitting unit 12 are formed. Since a luminescent substance such as 12 is easily oxidized and easily deteriorates when it comes into contact with water, when a plastic substrate is used as the support substrate 15, the light emitting functional portion 17 is covered by the support substrate 15 and the sealing substrate 18. Even if it is used, it tends to change with time, so it is preferable to preliminarily apply a treatment for enhancing the gas barrier property to the plastic substrate. For example, it is preferable to laminate a lower sealing film having a high barrier property against gas and liquid on a plastic substrate, and then laminate a light emitting function portion on the lower sealing film. This lower sealing film is usually formed of the same structure and the same material as the sealing substrate (upper sealing film) 18.

&lt;H&gt; Any layer The organic EL element 10 shown in FIG. 1 shows a form in which a first light emitting unit 11, a second light emitting unit 12, and a charge generation layer 13 are provided between the anode 14 and the cathode 16. However, the configuration of the layer provided between the anode 14 and the charge generation layer 13 and between the charge generation layer 13 and the cathode 16 is not limited to the configuration example shown in FIG. A first organic light emitting layer 11a, a second organic light emitting layer 12, and a charge generating layer 13 may be provided between the anode 14 and the cathode 16 as essential configurations, and hole injection of the first light emitting unit 11 is required. Like the layer 11b, the first light emitting unit 11 and the second light emitting unit 12 are provided with one or more other functional layers in addition to the first organic light emitting layer 11a and the second organic light emitting layer 12. You may. Examples of the layer that can be attached as a part of the first light emitting unit 11 and the second light emitting unit 12 include a hole injection layer, a hole transport layer, an electron block layer, an electron injection layer, and an electron transport layer as described above. , Hole block layer and the like.

The layers that can be provided between the anode 14 and the first organic light emitting layer 11a and between the charge generation layer 13 and the second organic light emitting layer 12 include a hole injection layer, a hole transport layer, an electron block layer, and the like. Can be mentioned. Charge generation occurs when both the hole injection layer and the hole transport layer are provided between the anode 14 and the first organic light emitting layer 11a, and between the charge generation layer 13 and the second organic light emitting layer 12. The layer in contact with the layer or the anode is called a hole injection layer, and the layer excluding the hole injection layer is called a hole transport layer.

Examples of the layers that can be provided between the first organic light emitting layer 11a 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, and a hole block layer. Can be mentioned. When both the electron injection layer and the electron transport layer are provided between the first organic light emitting layer 11a and the charge generation layer 13 and between the second organic light emitting layer 12 and the cathode 16, the charge generation layer or The layer in contact with the cathode is called an electron injection layer, and the layer excluding this electron injection layer is called an electron transport layer.

The hole injection layer and the electron injection layer may be 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. Further, the electron block layer and the hole block layer may be collectively referred to as a charge block layer. Two or more charge transport layers may be used independently of each other.

Hereinafter, any functional layer (not shown) including the hole injection layer 11b will be described. As an arbitrary layer constituting the light emitting unit, as described above, a hole injection layer, a hole transport layer, an electron block layer, an electron injection layer, an electron transport layer, and a hole block layer may be provided. &lt;H-1&gt; 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 provided between the anode 14 and the hole transport layer, between the anode 14 and the first organic light emitting layer 11a, between the charge generation layer 13 and the second organic light emitting layer 12, and the second. It can be provided between the organic light emitting layer 12 and the hole transport layer. As the material constituting the hole injection layer, a material having an ionization potential between one surface of the hole injection layer and each ionization potential of the two layers provided adjacent to the other surface is preferable. Specifically, a material having an ionization potential between the ionization potential of the anode 14 and the ionization potential of the surface portion of the first organic light emitting layer 11a on the anode 14 side, the ionization potential of the charge generation layer 13 and the second A material having an ionization potential between the surface portion of the organic light emitting layer 12 on the charge generation layer 13 side and the ionization potential. For example, conductive polymers such as phthalocyanine derivatives and polythiolen derivatives, layers having a thickness of 1 to 200 nm such as molybdenum oxides, amorphous carbons, carbon fluorides, and polyamine compounds, or metal oxides, metal fluorides, organic insulating materials, etc. A layer with a thickness of 2 nm or less is desirable. The conductive polymer materials include polyaniline and its derivatives, polythiophene and its derivatives, polypyrrole and its derivatives, polyphenylene vinylene and its derivatives, polythienylene vinylene and its derivatives, polyquinolin and its derivatives, polyquinoxalin and its derivatives, and aromatics. Examples thereof include polymers containing an amine structure in the main chain or side chains. The electrical conductivity of the conductive polymer is 10^-7S / cm or more 10³It is preferably S / cm or less, and when the organic EL element functions as a pixel of the display device, in order to reduce the leakage current between the pixels, 10^-5S / cm or more 10²S / cm or less is more preferable, 10^-5S / cm or more 10¹S / cm or less is more preferable. Normally, the electrical conductivity of the conductive polymer is 10^-5S / cm or more 10³In order to increase the hole injection property at S / cm or less, the conductive polymer is doped with an appropriate amount of anion. As an example of the anion, polystyrene sulfonate ion, alkylbenzene sulfonic acid ion, cerebral sulfonic acid ion and the like are preferably used.

The hole injection layer can be formed by the same method as the method for forming the first organic light emitting layer 11a and the second organic light emitting layer 12 described above. Specifically, a coating liquid in which a material to be a hole injection layer (hole injection material) is dissolved in a solvent similar to a solvent for dissolving a light emitting material mainly constituting an organic light emitting layer is applied by a conventional coating method. A film can be formed by coating.

The optimum film thickness of the hole injection layer differs depending on the material used, and is appropriately set so that the drive voltage and luminous efficiency are appropriate values, and at least a thickness that does not cause pinholes is required. If it is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film 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. &lt;H-2&gt; 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. The material constituting the hole transport layer is not particularly limited, but for example, N, N'-diphenyl-N, N'-di (3-methylphenyl) 4,4'-diaminobiphenyl (TPD), 4 , 4'-Bis [N- (1-naphthyl) -N-phenylamino] Aromatic amine derivatives such as biphenyl (NPB), polyvinylcarbazole or its derivatives, polysilanes or derivatives thereof, aromatic amines on the side chain or main chain Polysiloxane derivative, pyrazoline derivative, arylamine derivative, stillben derivative, triphenyldiamine derivative, polyaniline or its derivative, polythiophene or its derivative, polyarylamine or its derivative, polypyrrole or its derivative, poly (p-phenylene vinylene) Alternatively, a derivative thereof, or poly (2,5-thienylene vinylene) or a derivative thereof is exemplified.

Among these, as the hole transport material used for the hole transport layer, polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, a polysiloxane derivative having an aromatic amine compound group in the side chain or the main chain, polyaniline or a derivative thereof, High molecular weight hole transporting materials such as polythiophene or a derivative thereof, polyarylamine or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, or poly (2,5-thienylene vinylene) or a derivative thereof are preferable, and more preferable. Is polyvinylcarbazole or a derivative thereof, polysilane or a derivative thereof, or a polysiloxane derivative having an aromatic amine in the side chain or main chain. In the case of a low-molecular-weight hole transport material, it is preferable to disperse it in a polymer binder.

The method for forming the hole transport layer is not particularly limited, but as a low-molecular-weight hole transport material, film formation from a mixed solution containing a polymer binder and a hole transport material can be mentioned. Examples of the molecular hole transport material include film formation from a solution containing the hole transport material.

The solvent used for film formation from the solution is not particularly limited as long as it dissolves the hole transport material, and is a chlorine-based solvent such as chloroform, methylene chloride, or dichloroethane, an ether-based solvent such as tetrahydrofuran, toluene, and xylene. Examples thereof include aromatic hydrocarbon solvents such as, ketone solvents such as acetone and methyl ethyl ketone, and ester solvents such as ethyl acetate, butyl acetate and ethyl cell solve acetate. As a method for forming a film from a solution, a coating method similar to the above-mentioned method for forming a hole-injected layer can be mentioned.

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

The optimum film thickness of the hole transport layer differs depending on the material used, and it may be selected so that the drive voltage and luminous efficiency are appropriate values, but at least the thickness must be such that pinholes do not occur. If it is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the hole transport layer is, for example, 1 nm to 1 μm, preferably 2 nm or more and 500 nm or less, and more preferably 5 nm or more and 200 nm or less.

&lt;H-3&gt; Electronic block layer The electron block layer is a layer having a function of blocking the transport of electrons. If the hole injection layer and / or the hole transport layer has a function of blocking the transport of electrons, these layers may also serve as an electron block layer. The fact that the electron block layer has a function of blocking the transport of electrons makes it possible to, for example, manufacture an element that allows only an electron current to flow, and confirm the effect of blocking by reducing the current value. As the electron block layer, for example, various materials exemplified as the material of the hole injection layer or the hole transport layer can be used.

&lt;H-4&gt; 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 may be used between the first organic light emitting layer 11a 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. It is provided between the layer and the cathode 16. As the material for forming the electron injection layer, a material having an electron affinity between the electron affinity of one surface of the electron injection layer and the electron affinity of the two layers provided adjacent to the other surface is preferable. Specifically, a material having an electron affinity between the electron affinity of the charge generation layer 13 and the electron affinity of the surface portion of the first organic light emitting layer 11a on the charge generation layer 13 side, the electron affinity of the cathode 16 and the first. It is a material having an electron affinity between the electron affinity of the surface portion of the organic light emitting layer 12 on the cathode 16 side of 2. Examples of the electron injection layer include metal fluorides, metal oxides, and organic insulating materials depending on the type of the organic light emitting layer. Among them, metal fluorides such as alkali metals or alkaline earth metals and metal oxidation The thing is preferable. A conductive polymer material is also used. As the material of the conductive polymer, the polymer material having the electric conductivity described in the hole injection material may be used, but in order to improve the electron injection property, an appropriate amount of cation is doped. Examples of cations include lithium ion, sodium ion, potassium ion, tetrabutylammonium ion and the like.

Examples of alkali metals or their oxides, halides and carbon oxides are lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride and rubidium oxide. , Rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate and the like.

Examples of the alkaline earth metal or its oxide, halide, and carbon oxide include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, calcium fluoride, barium oxide, and foot. Examples thereof include barium carbonate, strontium oxide, strontium fluoride, and magnesium carbonate.

Further, an organometallic compound and an organometallic complex compound doped with a metal, a metal oxide or a metal salt, or a mixture thereof can also be used as a material for the electron injection layer.

This electron injection layer may have a laminated structure in which two or more layers are laminated. Specific examples include Li / Ca. This electron injection layer is formed by a vapor deposition method, a sputtering method, a printing method, or the like. The film thickness of the electron injection layer is preferably about 1 nm or more and about 1 μm or less.

&lt;H-5&gt; Electron transport layer The electron transport layer is a layer having a function of improving electron injection from a cathode, a charge generation layer, an electron injection layer or an electron transport layer closer to the cathode, and an electron transport layer is a layer having a function of transporting electrons. .. Known materials can be used to form the electron transport layer, and oxadiazole derivatives, anthracinodimethane or its derivatives, benzoquinone or its derivatives, naphthoquinone or its derivatives, anthraquinone or its derivatives, tetracyanoanthraquinodi Examples thereof include methane or a derivative thereof, fluorenone derivative, diphenyldicyanoethylene or a derivative thereof, a diphenoquinone derivative, or a metal complex of 8-hydroxyquinoline or a derivative thereof, polyquinolin or a derivative thereof, polyquinoxaline or a derivative thereof, polyfluorene or a derivative thereof, and the like. Derivatives.

Of these, oxaziazole derivatives, benzoquinone or its derivatives, anthraquinone or its derivatives, or metal complexes of 8-hydroxyquinone or its derivatives, polyquinoline or its derivatives, polyquinoxalin or its derivatives, polyfluorene or its derivatives are preferable. Further preferred are 2- (4-biphenylyl) -5- (4-t-butylphenyl) -1,3,4-oxadiazole, benzoquinone, anthraquinone, tris (8-quinolinol) aluminum and polyquinoline.

The method for forming a film of the electron transport layer is not particularly limited, and examples of the low molecular weight electron transport material include a vacuum vapor deposition method from powder, a method of forming a film from a solution or a molten state, and the like. Further, in the polymer electron transport material, a method of forming a film from a solution or a molten state is exemplified. Further, when forming a film from a solution or a molten state, a polymer binder may be used in combination. Examples of the method for forming the electron transport layer from the solution include the same film forming method as the method for forming the hole injection layer from the above-mentioned solution.

The optimum film thickness of the electron transport layer differs depending on the material used, and it may be selected so that the drive voltage and luminous efficiency are appropriate values, but at least the thickness must be such that pinholes do not occur. If it is too thick, the drive voltage of the element becomes high, which is not preferable. Therefore, the film thickness of the electron transport 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.

&lt;H-6&gt; Hole block layer The hole block layer is a layer having a function of blocking the transport of holes. If the electron injection layer and / or the electron transport layer has a function of blocking the transport of holes, these layers may also serve as a hole block layer. The fact that the hole block layer has a function of blocking the transport of holes makes it possible to manufacture an element that allows only the hole current to flow, and to confirm the effect of blocking by reducing the current value.

&lt;I&gt; Combination of layer structure of light emitting unit As described above, the light emitting unit included in the light emitting function unit may adopt various layer configurations as its embodiment. Specific examples of possible layer configurations of the light emitting unit are 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 the layers sandwiching the symbol "/" are laminated adjacent to each other. The same shall apply hereinafter.) In the above configurations a) to i), the left side is the layer near the anode and the right side is the layer near the cathode.

The plurality of light emitting units included in the organic EL element may have the same layer structure or different layer structures from each other. The first light emitting unit 11 of the present embodiment shown in FIG. 1 has a configuration of b), that is, a configuration in which the hole injection layer 11b and the first organic light emitting layer 11a are laminated, and the second light emitting unit 12 Consists of the configuration of a) above, that is, only the second organic light emitting layer.

The organic EL device according to the present invention is a multiphoton type organic EL device having a configuration in which a plurality of light emitting units are stacked in a plurality of stages via a charge generation layer. In the organic EL element 10 of the present embodiment shown in FIG. 1, as described above, two sets of light emitting units are used, and the first light emitting unit 11 and the second light emitting unit 12 are laminated via the charge generation layer 13. There is. Further, as a modification thereof, a multiphoton type organic EL element having a configuration in which three or more sets of light emitting units are laminated via a charge generation layer can also be adopted.

In the organic EL element, the anode is usually arranged on the substrate side, but the cathode may be arranged on the substrate side.

Further, as another arbitrary functional layer, an insulating layer having a film thickness of 2 nm or less may be provided adjacent to the electrode, for example, in order to improve the adhesion to the electrode and the charge injection property from the electrode. Further, as another optional functional layer, a thin buffer layer may be inserted between the above-mentioned layers in order to improve the adhesion of the interface and prevent mixing.

In the embodiment shown in FIG. 1, an anode 14 is provided on the support substrate 15. In these cases, in each of the above a) to i) forms, the layers are arranged on the support substrate 15 in order from the layer shown on the left side (anode side).

On the other hand, as the organic EL element of the present invention, a form in which a cathode is arranged on a support substrate can also be adopted. In this case, in each of the above a) to i) forms, the layers are arranged on the support substrate in order from the layer shown on the right side (cathode side).

[Second Embodiment] Next, a second embodiment of the organic EL device according to the present invention will be described with reference to FIG. FIG. 2 is a front view showing a second embodiment of the organic EL device of the present invention. In FIG. 2, the same members as those in the first embodiment are designated by the same reference numerals as those in FIG. 1, and duplicated description will be omitted. Hereinafter, the points different from the first embodiment will be mainly described. The organic EL element 10 of the first embodiment transmits the light from the first light emitting unit 11 and the second light emitting unit 12 through the light transmitting anode 14 to the outside from the light transmitting support substrate 15. Whereas the organic EL element 20 of the second embodiment is a bottom emission type element that emits light to, the organic EL element 20 of the second embodiment transmits light from the first light emitting unit 11 and the second light emitting unit 12 to a cathode having light transmission. This is a top-emission type element that transmits light (first electrode) 21 and emits light from the sealing substrate 18 to the outside.

In the present embodiment, the cathode 21 is the first electrode having light transmittance for transmitting the light from the first light emitting unit 11 and the second light emitting unit 12. The light emitting function unit 23 including the cathode 21, the second light emitting unit 12, the charge generation layer 13, the first light emitting unit 11 and the anode (second electrode) 22 is formed from the sealing substrate 18 closer to the first main surface 18a. They are laminated on the support substrate 15 in this order. The film 19 is provided on the outermost layer in the light extraction direction, and is provided on the sealing substrate 18 in the present embodiment. That is, the sealing substrate 18 is interposed between the cathode 21 and the film 19, and the film 19 is provided in contact with the second main surface 18b.

Further, as the cathode 21 in the present embodiment, for example, a metal thin film exemplified as the first electrode which is a transparent anode can be used as the transparent cathode. Since the metal thin film used for the cathode 21 is formed into a thin film to the extent that light can be transmitted, the sheet resistance is high. Therefore, it is preferable that the cathode 21 is composed of a laminated body in which transparent electrodes such as ITO thin films are laminated on a metal thin film. Further, it is preferable to provide a highly reflective reflective film such as silver between the anode 22 and the support substrate 15, and by providing such a reflective film, light directed to the support substrate 15 side is directed to the cathode 21 side. It can be reflected and the efficiency of light extraction can be improved.

Also in the organic EL element 20 according to the present embodiment, the same actions and effects as those of the organic EL element according to the first embodiment can be obtained. Even if the multi-photon type organic EL element 20 as a whole is driven so as to have the same amount of light as the single photon type organic EL element, the organic EL element 20 is the first and first than the single photon type organic EL element. Since the light can be emitted in a state where the load applied to the organic light emitting layers 11a and 12 of 2 is reduced, the life of the device can be extended. Further, a film 19 is provided on the outermost layer on the cathode 21 side based on the first and second light emitting units 11 and 12, and the surface opposite to the first and second light emitting units 11 and 12 is made uneven. Since the haze value is 70% or more and the total light transmittance is 80% or more, the light extraction efficiency can be increased. Therefore, the organic EL device according to the present embodiment can also extend the life of the device and increase the light extraction efficiency, so that a multiphoton type organic EL device having better light emission performance can be realized. Can be done.

2. A device equipped with the organic EL element of the present invention. The organic EL element of each embodiment of the present invention described above can be suitably used for a curved or planar lighting device, for example, a planar light source used as a light source for a scanner, or a display device.

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. Further, the organic EL element is used as a light emitting element constituting each segment in the segment display device. Further, the organic EL element is used as a backlight in a dot matrix display device and a liquid crystal display device.

Further, as described above, the organic EL element of the embodiment of the present invention is provided with a recess on the surface of the film 19 that exhibits a function similar to that of a concave lens, so that illumination with a wide radiation angle can be realized.

Hereinafter, the present invention will be described in more detail based on Production Examples and Comparative Examples, but the present invention is not limited to the following Production Examples and the like.

&lt;Verification of luminous efficiency of multi-photon type organic EL element&gt; In Production Examples 1-1 and 1-2 and Comparative Examples 1-1 to 1-4, an organic EL device having a structure in which two light emitting units are separated by one charge generation layer was produced, and the effect was confirmed.

&lt;Manufacturing example 1-1&gt; Manufacture of an organic EL device having a structure partitioned by a charge generation layer (Layer structure of Production Example 1-1: ITO / PEDOT / MEH-PPV / Li / V₂O₅/ MEH-PPV / Al-Li alloy) An example of manufacturing the organic EL device in Production Example 1-1 will be described with reference to FIG. In the organic EL element 10 shown in FIG. 1, a substrate in which an ITO film used as an anode 14 is formed to a thickness of 150 nm by a sputtering method is prepared on a glass substrate 15 corresponding to a support substrate, and PEDOT made by BYTRON (PEDOT) is prepared on the substrate. A poly (3,4-ethylenedioxythiophene)) / PSS (polystyrene sulfonic acid) solution is formed into a film with a thickness of 40 nm by the spin coating method, and heat-treated at 200 ° C in a nitrogen atmosphere to form a hole injection layer 11b. did. Next, as a luminescent material, 1 wt% toluene of MEH-PPV (poly (2-methoxy-5- (2'-ethyl-hexyloxy) -para-phenylene vinylene) manufactured by Aldrich with a weight average molecular weight of about 200,000). A solution was prepared and spin-coated on a substrate on which PEDOT / PSS was formed to form a first organic light emitting layer 11a with a film thickness of 90 nm. A hole injection layer 11b and a first organic light emitting layer were formed. The layers 11a are combined to form the first light emitting unit 11.

Li (work function: 2.93eV), V as the charge generation layer 13 by the vacuum deposition method on this.₂O₅(Vanadium oxide) (work function: 4 eV or more) was sequentially formed with thicknesses of 2 nm and 20 nm, respectively, to form the first layer 13-1 and the second layer 13-2. Here, Li vapor deposition 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, V₂O₅Was vapor-deposited. In addition, V₂O₅A 1 wt% toluene solution of MEH-PPV was spin-coated on the 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 was formed at 100 nm as a cathode 16 by a vacuum vapor deposition method. From the above, an organic EL device having a structure in which two light emitting units are separated by one charge generation layer is manufactured. When a DC voltage was applied to the obtained element, the emission start voltage was 12 V and the maximum brightness was 80 cd / m.²Met. The current efficiency was 0.072 cd / A, which was 1.95 times higher than that of the element (0.037 cd / A) of Comparative Example 1-1 below.

&lt;Comparative Example 1-1&gt; Fabrication of Organic EL Element (Layer structure of Comparative Example 1-1: ITO / PEDOT / MEH-PPV / Al-Li alloy) For comparison, FIG. 3 shows the same as in Production 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 Production Example 1-1. As described above, the organic EL element 30 having only one light emitting unit 11 was manufactured. In FIG. 3, the same members as those in FIG. 1 are designated by the same reference numerals. When a DC voltage was applied to the organic EL element 30 in Comparative Example 1-1, the emission start voltage was 5.5 V and the maximum brightness was 52 cd / m.²Met. The current efficiency was 0.037 cd / A.

&lt;Comparative Example 1-2&gt; Fabrication of Organic EL Element (Layer configuration of Comparative Example 1-2: ITO / PEDOT / MEH-PPV / V₂O₅/ MEH-PPV / Al-Li alloy) As a charge generation layer, V with a film thickness of 30 nm₂O₅An organic EL device was produced in the same manner as in Comparative Example 1-1, except that the one composed of only one layer was used. The obtained device did not emit light even when 40 V was applied.

&lt;Manufacturing Example 1-2&gt; A color mixing element composed of laminated light emitting units of different colors. (Layer structure of Production Example 1-2: ITO / PEDOT / F8-TPA-BT / Li / V₂O₅/ PEDOT / PSS / F8-TPA-PDA / Al-Li alloy) Polymer light emitting material 31 (abbreviated as F8 (abbreviation F8 (9,9-dioctylfluorene)) represented by the following structural formula (1) that emits green light instead of MEH-PPV which is the organic light emitting layer in Production Example 1-1. After forming the first light emitting unit 11 including the polymer light emitting layer composed of -TPA (triphenylamine) -BT (polypisamide triazole) and the charge generating layer 13, the PEDOT / PSS layer is formed. A second light emitting unit including a polymer light emitting layer made of a polymer light emitting material 32 (abbreviated as F8-TPA-PDA (p-phenylenediamine)) represented by the following structural formula (2) that subsequently emits blue light. After forming a film of No. 12, a cathode was formed in the same manner as in Production Example 1-1 to produce light emitting elements having different emission wavelengths from the two light emitting units.

Polymer luminescent material 31<chemistry num="1"><img file="JP2010146893A_D0001.tif" /></chemistry>

Polymer luminescent material 32<chemistry num="2"><img file="JP2010146893A_D0002.tif" /></chemistry>

&lt;Comparative Examples 1-3 and 1-4&gt; Comparison of Production Examples 1-2, Single element consisting of only green and blue organic light emitting layers (Layer structure 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 Production Example 1-2, an element consisting of one light emitting unit having an ITO / PEDOT / organic light emitting layer / Al-Li alloy structure was produced in the same manner as in Comparative Example 1-2. Here, in Comparative Example 1-3, the green light emitting layer material F8-TPA-BT was used for the organic light emitting layer, and in Comparative Example 1-4, the blue light emitting material F8-TPA-PDA was used for the organic light emitting layer.

The drive voltages of Comparative Examples 1-3 and 1-4 were 3.6V and 5.4V, respectively, whereas in Production Example 1-2, they were 8.0V, which was close to the expected voltage of the element in which the two units were stacked. Further, in the device of Production Example 1-2, the spectrum was widened and whitish green emission was obtained by mixing the colors from the two layers.

Next, in the following Production Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3, it was confirmed that the light extraction efficiency can be controlled by providing a film on the outer surface of the transparent support substrate.

&lt;Production Example 2-1&gt; Fabrication of an organic EL device having a film An organic EL device having a film was produced as follows. A glass substrate of 30 mm × 30 mm was used as a transparent support substrate having light transmission. Next, a conductor film made of ITO having a thickness of 150 nm was deposited on the surface of the support substrate by a sputtering method. Next, a photoresist was applied on the surface of the conductor film, a predetermined area was exposed through a photomask, and further washed to form a protective film having a predetermined pattern shape. After further etching, it was rinsed with water and NMP (n-methylpyrrolidone) to form an anode composed of an ITO film having a predetermined pattern shape. Next, in order to remove the resist residue on the anode, oxygen plasma treatment was performed at 30 W energy for 2 minutes, and UV / O was performed.₃Washing was performed for 20 minutes.

Next, a suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (manufactured by Stark Vitec, trade name: Baytron P CH8000) is filtered in two stages to provide a solution for the hole injection layer. Got A 0.45 μm diameter filter was used in the first stage filtration, and a 0.2 μm diameter filter was used in the second stage filtration. A thin film is formed by a spin coating method using the solution obtained by filtration, and a hole injection layer having a thickness of 70 nm is formed by heat-treating on a hot plate at 200 ° C. for 15 minutes in an atmospheric atmosphere. Formed.

Next, Lumation WP1330 (manufactured by SUMATION) and xylene were mixed to prepare a xylene solution. The concentration of Lumation WP1330 in the xylene solution was set to 1.2% by mass. A thin film is formed on the surface of the hole injection layer by the spin coating method using the prepared solution, and then heat-treated on a hot plate at 130 ° C. for 60 minutes in a nitrogen atmosphere to form an organic light emitting layer having a thickness of 80 nm. Was formed.

Next, the support substrate on which the organic light emitting layer was formed was introduced into a vacuum vapor deposition machine, and Ba and Al were sequentially vapor-deposited at thicknesses of 5 nm and 80 nm, respectively, to form a cathode. The degree of vacuum is 1 x 10^-4After reaching Pa or less, metal deposition was started.

Next, in order to prepare a film, a solution for the film was first prepared. 6.32 g of polycarbonate was dissolved in 20.7 g of dichloromethane to prepare a 23.4 wt% solution. Next, Novec (manufactured by Sumitomo 3M Ltd.), which is a fluorine-based surfactant, was mixed with this solution. The concentration of Novec in the mixed solution was set to 0.8 wt% to obtain a solution for a film. The obtained film solution was cast on a glass base so that the film thickness after film formation was about 150 μm in a constant temperature and humidity chamber having a humidity of 85%. After leaving the film in an atmosphere of 85% humidity for 5 minutes, the film was dried by a nitrogen flow to obtain a 20 mm × 20 mm film (film A) having an uneven shape on the surface.

Next, glycerin was applied as an adhesive to the surface of the support substrate opposite to the surface on the side on which the organic light emitting layer was formed, and the film A was bonded to prepare an organic EL device. The refractive index of the support substrate is 1.50, the refractive index of the pressure-sensitive adhesive is 1.45, and the refractive index of film A is 1.58. The average film thickness of the film A is 230 μm.

&lt;Manufacturing Example 2-2&gt; Manufacture of an organic EL device having a film An organic EL device different only in the film from the organic EL device of Production Example 2-1 was manufactured. In this production example 2-2, a commercially available film (film B) showing a high haze value (82%) was used. Since the film B has an adhesive layer, it is directly attached to a support substrate without using an adhesive or the like to produce an organic EL element.

&lt;Comparative Example 2-1&gt; Fabrication of Organic EL Device with Film An organic EL device different from the organic EL device of Production Example 2-1 only in the film was manufactured. As the solution for the film, the same solution as that of Preparation Example 2-1 was used. The film solution was cast on a glass base so that the film thickness after film formation was about 220 μm in a constant temperature and humidity chamber having a humidity of 50%. After standing for 5 minutes in an atmosphere of 50% humidity, the film was dried by a nitrogen flow to obtain a 20 mm × 20 mm film (film C). This film C was attached to a support substrate in the same manner as in Production Example 2-1 using the same adhesive as in Production Example 2-1 to produce an organic EL device.

&lt;Comparative Example 2-2&gt; Fabrication of Organic EL Device with Film An organic EL device different only in the film from the organic EL device of Production Example 2-1 was manufactured. As the solution for the film, the same solution as that of Preparation Example 2-1 was used. In a constant temperature and humidity chamber with a humidity of 85%, the film solution was cast on a glass base so that the film thickness after film formation was about 220 μm. After leaving the film in an atmosphere of 85% humidity for 5 minutes, the film was dried by a nitrogen flow to obtain a 20 mm × 20 mm film (film D) having an uneven shape on the surface. The obtained film D was attached to a support substrate in the same manner as in Production Example 2-1 using the same adhesive as in Production Example 2-1 to prepare an organic EL device.

&lt;Comparative Example 2-3&gt; Fabrication of Organic EL Device with Film An organic EL device different only in the film from the organic EL device of Production Example 2-1 was manufactured. As the solution for the film, the same solution as that of Preparation Example 2-1 was used. In a constant temperature and humidity chamber with a humidity of 85%, the film solution was cast on a glass base so that the film thickness after film formation was about 360 μm. After leaving the film in an atmosphere of 85% humidity for 5 minutes, the film was dried by a nitrogen flow to obtain a 20 mm × 20 mm film (film E) having an uneven shape on the surface. This film E was attached to a support substrate in the same manner as in Production Example 2-1 using the same adhesive as in Production Example 2-1 to prepare an organic EL device.

&lt;Observation of film surface&gt; The surfaces of the films used in Preparation Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3 were observed with a scanning electron microscope (SEM). FIG. 6 is a diagram schematically showing a cross section of the film A produced in Production Example 2-1 and FIG. 7 is a diagram schematically showing a cross section of the film B used in Production Example 2-2. FIG. 8 is a diagram schematically showing a cross section of the film C produced in Comparative Example 2-1.

As shown in FIG. 6, in the film A produced in Production Example 2-1 it was confirmed that a hemispherical recess having an average diameter of 2 μm was formed on the surface of the film. It was confirmed that the recess was formed over the entire surface of the film A.

Further, as shown in FIG. 7, in the film B used in Production Example 2-2, it was confirmed that the surface of the film was formed in an uneven shape. It was confirmed that the recess was formed over the entire surface of the film B.

Further, as shown in FIG. 8, in the film C produced in Comparative Example 2-1 it was confirmed that the surface was flat without forming recesses on the surface.

Further, in the film D produced in Comparative Example 2-2, it was confirmed that a hemispherical concave surface having an average diameter of 3 μm was formed on the surface of the film. Although the regularity of the arrangement of the concave surfaces was relatively low, it was confirmed that the concave surfaces were formed over the entire surface of the film D.

Further, in the film E produced in Comparative Example 2-3, it was confirmed that a hemispherical concave surface having an average diameter of 4 μm was formed on the surface of the film. Although the regularity of the arrangement of the concave surfaces was relatively low, it was confirmed that the concave surfaces were formed over the entire surface of the film E.

Table 1 shows the humidity when the films were prepared in Production Examples 2-1 and Comparative Examples 2-1 to 2-3, and used in Production Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3. The characteristics of the film that was used are shown.

<tables num="1"><img file="JP2010146893A_D0003.tif" /></tables>

As shown in Table 1, it was confirmed that a film having a high haze value can be produced by controlling the humidity and the film thickness of the produced film. It was also confirmed that the diameter of the concave surface increased as the film thickness of the produced film increased.

&lt;Light extraction efficiency of organic EL elements&gt; Comparing the light intensity of the organic EL element to which the films prepared in Production Examples 2-1 and 2-2 and Comparative Examples 2-1 to 2-3 are bonded with the light intensity of the organic EL element to which the film is not bonded. did. Table 2 shows the ratio of the light extraction efficiency obtained by dividing the light intensity of the organic EL element to which the film is attached by the light intensity of the organic EL element to which the film is not attached. The light intensity was measured by passing a current of 0.15 mA through the organic EL element, measuring the angle dependence of the light emission intensity at that time, and integrating the light emission intensity at all angles.

<tables num="2"><img file="JP2010146893A_D0004.tif" /></tables>

The organic EL device of Production Example 2-1 had a 1.5-fold increase in light extraction efficiency as compared with that before the film A was bonded. Furthermore, the organic EL device of Production Example 2-2, in which the film A of Production Example 2-1 and the film B having similar optical characteristics are bonded to each other, also have high light extraction efficiency, similar to the organic EL element of Production Example 2-1. Rose. However, the film C used for the organic EL device of Comparative Example 2-1 had almost no light scattering, so that the light extraction efficiency was not improved. Also, in Comparative Examples 2-2 and 2-3, no significant improvement in light extraction efficiency was observed.

From this, it was clarified that the film having high total light transmittance and high haze value contributed to the improvement of light extraction efficiency. In particular, it was found that when the haze value of the film was 70% or more, the light extraction efficiency was greatly improved. It was confirmed that the light extraction efficiency was improved by providing the film exhibiting the predetermined optical characteristics in this way.

<figref num="1">It is a front view which shows the 1st Embodiment of the organic EL element of this invention.</figref><figref num="2">It is a front view which shows the 2nd Embodiment of the organic EL element of this invention.</figref><figref num="3">It is a front view which shows the structure of the conventional organic EL element.</figref><figref num="4">It is a figure which shows typically the cross section of a film.</figref><figref num="5">It is a figure which shows the other cross section of a film schematically.</figref><figref num="6">It is a figure which shows typically the cross section of the film A produced in the production example 2-1.</figref><figref num="7">It is a figure which shows typically the cross section of the film B used in the production example 2-2.</figref><figref num="8">It is a figure which shows typically the cross section of the film C produced in the comparative example 2-1.</figref>

Code description

10, 20 organic EL elements 11 First light emitting unit 11a First organic light emitting layer 11b hole injection 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 (1st electrode) 15 Support board 16 Cathode (second electrode) 17, 23 Light emitting function 18 Encapsulation substrate (upper encapsulation film) 19 film 19a, 19d convex part 19c Flat surface 19b, 19e recess 21 Cathode (1st electrode) 22 Anode (second electrode) A Film used in Production Example 2-1 B Film used in Production Example 2-2 C Film used in Comparative Example 2-1