JP2010147243A - Organic electroluminescent element and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic EL element capable of forming layers by a simple method without requiring a vacuum atmosphere and having good luminescent characteristics and life characteristics, and to provide a method of manufacturing the same, an illumination device, a planar light source, and a display device. <P>SOLUTION: An organic EL element 1 is formed by stacking a substrate 6, an anode 2, a metal-doped molybdenum oxide layer 7, a light emitting layer 4, an electron injection layer 5 and a cathode layer 3 in this order. The electron injection layer 5 is deposited by applying a layer formation coating liquid with an alkali metal salt dissolved therein to the surface of the light-emitting layer 4. The metal-doped molybdenum oxide layer 7 is obtained by depositing oxide molybdenum and dopant metal at the same time. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

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

  An organic EL element includes, for example, a light emitting layer containing an organic substance and a pair of electrodes (anode and cathode) sandwiching the light emitting layer, and holes are injected from the anode by applying a voltage to the pair of electrodes. At the same time, electrons are injected from the cathode, and these holes and electrons combine in the light emitting layer to emit light.

  A layer different from the light emitting layer is provided between the electrode and the light emitting layer for the purpose of lowering the driving voltage in the organic EL element and extending the life of the organic EL element. Examples of such a layer include an electron injection layer, a hole injection layer, a hole transport layer, and an electron transport layer (see, for example, Patent Document 1 or 2).

  The electron injection layer is formed by, for example, an evaporation method such as an electron beam (abbreviation EB) evaporation method or a resistance heating evaporation method. In such a method, since a vacuum apparatus is required to create a vacuum atmosphere, the apparatus and the process are complicated, and there is a problem that the manufacturing cost of the element increases.

  For example, Patent Document 3 describes providing an inorganic oxide layer such as molybdenum oxide between a light emitting layer and an electron injection electrode as a highly efficient electron injection layer. In manufacturing an organic EL element, a wet process is used for ease of process. For example, a light emitting layer is formed by a coating method, and a partition that partitions an organic EL element between pixels of a display device is formed by a photolithography method. However, the molybdenum oxide layer has low resistance to the wet process, and in the step of forming the organic EL element by the wet process, the molybdenum oxide layer may be damaged or may be eluted in some cases. Therefore, as a result, there is a problem that it is difficult to use a wet process with a simple process, and it is difficult to improve the light emission characteristics and life characteristics of the obtained organic EL element.

JP-A-9-17574 Japanese Patent Laid-Open No. 2000-24369 JP 2002-367784 A

  Accordingly, the present invention has been made in view of the above, and an organic EL element that can form an organic EL element by a simple method and has good light emission characteristics and lifetime characteristics, a manufacturing method thereof, a lighting device, It is an object to provide a planar light source and a display device.

  In order to solve the above-mentioned problems, the present inventors have studied a method of forming a layer by a coating method that does not require a vacuum atmosphere, and formed a layer with a layer-forming coating solution that can be used for the coating method. It has been found that by doping a metal with an oxide, durability against a film forming process such as a wet process can be improved, and as a result, the light emission characteristics and lifetime characteristics of the element can be improved.

  An organic electroluminescence device according to the present invention is an organic electroluminescence device having an anode, a cathode, and a light emitting layer interposed between the anode and the cathode, and a metal between the anode and the light emitting layer. A metal-doped molybdenum oxide layer made of doped molybdenum oxide, and a layer formed by a coating method using a layer-forming coating solution in which an alkali metal salt is dissolved, between the light emitting layer and the cathode; It is characterized by.

  Moreover, in the organic electroluminescent element by this invention, it is preferable that the visible light transmittance | permeability of the said metal dope molybdenum oxide layer is 50% or more.

  In the organic electroluminescence device according to the present invention, the dopant metal contained in the metal-doped molybdenum oxide is preferably selected from the group consisting of transition metals, Group 13 metals of the periodic table, and mixtures thereof. .

  Moreover, in the organic electroluminescent element by this invention, it is preferable that the said dopant metal is aluminum.

  Moreover, in the organic electroluminescent element by this invention, it is preferable that the ratio of the dopant metal in the said metal dope molybdenum oxide is 0.1-20.0 mol%.

  Moreover, in the organic electroluminescent element by this invention, it is preferable to have a layer containing a high molecular compound in contact with the said metal dope molybdenum oxide layer.

  The method of manufacturing an organic electroluminescence device according to the present invention includes a step of forming an anode, a cathode, and a light emitting layer interposed between the anode and the cathode, and a molybdenum oxide and a dopant metal between the anode and the light emitting layer. Forming a metal-doped molybdenum oxide layer formed by simultaneously depositing layers, and forming a layer by a coating method using a layer-forming coating solution in which an alkali metal salt is dissolved between the light emitting layer and the cathode; It is characterized by including.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable to perform the process of forming the said metal dope molybdenum oxide layer by vacuum evaporation, sputtering, or ion plating.

  In the method for manufacturing an organic electroluminescence device according to the present invention, it is preferable that the step of forming the metal-doped molybdenum oxide layer further includes a step of heating a layer in which molybdenum oxide and a dopant metal are simultaneously deposited. .

  In the method for producing an organic electroluminescence device according to the present invention, the alkali metal salt is selected from the group consisting of molybdic acid, tungstic acid, tantalic acid, niobic acid, vanadate acid, titanic acid, and zinc acid. Preferably it is at least one salt.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the said alkali metal salt is at least 1 sort (s) of salt selected from the group which consists of lithium, sodium, potassium, rubidium, and a cesium.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the said alkali metal salt is a cesium salt.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the said alkali metal salt is a cesium molybdate.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the said layer formation coating liquid contains alcohol and / or water.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the said layer formation coating liquid contains surfactant.

  In the method for producing an organic electroluminescent element according to the present invention, it is preferable that a contact angle of the layer forming coating solution with respect to a substrate made of polyethylene naphthalate is 60 ° or less.

  Moreover, in the manufacturing method of the organic electroluminescent element by this invention, it is preferable that the hydrogen ion index | exponent of the said layer formation coating liquid is 7 or more and 13 or less.

  The illuminating device by this invention is equipped with the said organic electroluminescent element, It is characterized by the above-mentioned.

  The planar light source according to the present invention includes the organic electroluminescence element.

  A display device according to the present invention includes the organic electroluminescence element.

  According to the present invention, by using the layer forming coating solution, a layer can be easily formed by a coating method without creating a vacuum atmosphere. In addition, by forming a metal-doped molybdenum oxide layer that is resistant to a wet process, even if each layer is formed by a wet process after the metal-doped molybdenum oxide layer is formed, damage to the metal-doped molybdenum oxide layer Therefore, a highly reliable organic EL device can be easily manufactured by a simple wet process, and its light emission characteristics and lifetime characteristics are good. Therefore, the organic EL device according to the present invention can be preferably used as a display device such as a planar light source used in a lighting device, a backlight, a scanner, or the like, or a flat panel display.

  Embodiments of the present invention will be described below with reference to the drawings. For ease of understanding, the scale of each member in the drawings may be different from the actual scale. Further, the present invention is not limited by the following description, and can be appropriately changed without departing from the gist of the present invention. In the organic EL device, there are members such as electrode lead wires. However, in the explanation of the present invention, the description is omitted because it is not required directly. For convenience of explanation of the layer structure and the like, in the following example, the explanation will be made together with a diagram in which the substrate is arranged below. It is not used. In some cases, one side in the thickness direction of the substrate is referred to as the upper side or the upper side, and the other side in the thickness direction of the substrate is referred to as the lower side.

  FIG. 1 is a front view showing an organic EL element 1 according to an embodiment of the present invention. The organic EL element 1 of the present embodiment is used for, for example, a light source of a display device such as a full-color display device or an area color display device, a planar light source used for a backlight or a scanner of a liquid crystal display device, an illumination device, or the like. It is done.

  The organic EL element 1 of the present embodiment includes an anode 2, a cathode 3, a light emitting layer 4 provided between the anode 2 and the cathode 3, and an electron injection layer 5 provided between the cathode 3 and the light emitting layer 4. And a metal-doped molybdenum oxide layer 7 made of a metal-doped molybdenum oxide provided between the light emitting layer 4 and the anode 2. The organic EL element 1 of the present embodiment is configured by laminating an anode 2, a metal-doped molybdenum oxide layer 7, a light emitting layer 4, an electron injection layer 5 and a cathode 3 in this order on a substrate 6. Manufactured by filming. The electron injection layer 5 is formed by a coating method using a layer forming coating solution described later. The metal-doped molybdenum oxide layer 7 contains molybdenum oxide and a dopant metal, and preferably consists essentially of molybdenum oxide and a dopant metal, and functions as a hole injection layer in the present embodiment.

  The organic EL element 1 of the present embodiment is a so-called bottom emission type element that extracts light from the light emitting layer 4 from the substrate 6 side, and a substrate 6 having a high transmittance for light in the visible light region is preferably used. Further, as the substrate 6, a substrate that does not change in the process of forming the organic EL element 1 is preferably used, and may be a rigid substrate or a flexible substrate. For example, glass, plastic, polymer film, silicon substrate, metal plate, and these are laminated. And the like are preferably used. Further, a plastic, a polymer film or the like that has been subjected to a low water permeability treatment can be used. A commercially available substrate can be used as the substrate 6. The substrate 6 can be manufactured by a known method. In the so-called top emission type organic EL element that extracts light from the cathode 3 side, the substrate may be opaque.

  A thin film with low electrical resistance is preferably used for the anode 2. At least one of the anode 2 and the cathode 3 exhibits translucency. For example, in a bottom emission type organic EL element, the anode 2 disposed on the substrate 6 side has a transmittance for light in the visible light region. Higher ones are preferably used. The material of the anode 2 will be described later.

  The metal-doped molybdenum oxide layer 7 made of doped molybdenum oxide contains molybdenum oxide and a dopant metal. More specifically, the proportion of the total of the molybdenum oxide and the dopant metal in the total amount of the material constituting the metal-doped molybdenum oxide layer is preferably 98% by mass or more, more preferably 99% by mass or more, and still more preferably Is 99.9% by mass or more.

  From the viewpoint of device characteristics, it is preferable to provide a layer containing a polymer compound in contact with the metal-doped molybdenum oxide layer 7. The layer containing the polymer compound can be provided on either the upper or lower surface of the metal-doped molybdenum oxide layer 7, and in particular, the layer containing the polymer compound may be provided on the metal-doped molybdenum oxide layer 7. More preferred. That is, a layer containing a polymer compound is preferably provided on the surface of the metal-doped molybdenum oxide layer 7 on the cathode 3 side.

  The visible light transmittance of the metal-doped molybdenum oxide layer 7 is preferably 50% or more. By having a visible light transmittance of 50% or more, it can be suitably used for an organic EL element that emits light through the metal-doped molybdenum oxide layer 7.

The dopant metal contained in the metal-doped molybdenum oxide layer 7 is preferably a transition metal, a Group 13 metal of the periodic table, or a mixture thereof, more preferably aluminum, nickel, copper, chromium, titanium, silver, gallium, zinc. , Neodymium, europium, holmium, cerium, and more preferably aluminum. Moreover, it is preferable to employ MoO ₃ as the molybdenum oxide. When MoO ₃ is formed by a vapor deposition method such as vacuum vapor deposition, the stoichiometric composition ratio of Mo and O may not be maintained in the deposited film, but even in that case, it is preferably used in the present invention. be able to.

  It is preferable that the content rate of the dopant metal with respect to the molybdenum oxide in the said metal dope molybdenum oxide is 0.1-20.0 mol%. When the content of the dopant metal is within the above range, good process resistance can be obtained.

  The thickness of the metal-doped molybdenum oxide layer is not particularly limited, but is preferably 10 to 1000 mm.

  A method for forming the metal-doped molybdenum oxide layer 7 is not particularly limited, but on the lower layer (in this embodiment, the anode 2) disposed in contact with the metal-doped molybdenum oxide layer 7 in the organic EL element. A method in which molybdenum oxide and a dopant metal are simultaneously deposited to obtain a metal-doped molybdenum oxide layer 7 is preferable. Here, the lower layer disposed in contact with the metal-doped molybdenum oxide layer 7 in the organic EL element 1 can be appropriately selected according to the manufacturing process and the laminated structure of the organic EL element 1 to be obtained. For example, deposition can be performed on the layer of the anode 2 provided on the substrate, and the metal-doped molybdenum oxide layer 7 in direct contact with the anode 2 can be obtained. Deposition can be performed by vacuum evaporation, molecular beam evaporation, sputtering or ion plating, ion beam evaporation, or the like. By introducing plasma into the film formation chamber, a plasma assisted vacuum deposition method with improved reactivity and film formability can be used.

Examples of the evaporation source of the vacuum deposition method include resistance heating, electron beam heating, high frequency induction heating, and laser beam heating. As a simpler method, resistance heating, electron beam heating, and high frequency induction heating are preferable. The sputtering method includes a DC sputtering method, an RF sputtering method, an ECR sputtering method, a conventional sputtering method, a magnetron sputtering method, an ion beam sputtering method, an opposed target sputtering method, and any method can be used. In order not to damage the lower layer, it is preferable to use magnetron sputtering, ion beam sputtering, or counter target sputtering. Note that during film formation, vapor deposition can be performed by introducing a gas containing oxygen or an oxygen element into the atmosphere. As a combination of materials used for forming the metal-doped molybdenum oxide layer 7, MoO ₃ and a single metal to be doped are usually used, but a combination of molybdenum itself or MoO ₂ and an oxide of a dopant metal is also possible. It is possible. Further, the metal-doped molybdenum oxide layer 7 may be formed using an alloy of dopant metal and molybdenum or a mixture thereof as a material.

The deposited metal-doped molybdenum oxide layer is preferably subjected to heat treatment, UV-O ₃ treatment, air exposure treatment, and the like as optional steps, and among these treatments, heat treatment is preferably performed. By performing these treatments, the resistance to the wet process and the life characteristics of the metal-doped molybdenum oxide can be further enhanced.

The heating can be performed at 50 to 350 ° C. for 1 to 120 minutes. The UV-O ₃ treatment can be performed by irradiating with ultraviolet rays at an intensity of 1 to 100 mW / cm ² for 5 seconds to 30 minutes and in an atmosphere having an ozone concentration of 0.001 to 99%. The exposure to the atmosphere can be performed by leaving it in the atmosphere at a humidity of 40 to 95% and a temperature of 20 to 50 ° C. for 1 to 20 days.

  The light emitting layer 4 includes an organic substance that emits fluorescence and / or phosphorescence, and may further include a dopant. The dopant is added for the purpose of, for example, improving luminous efficiency or changing the emission wavelength. The light emitting material used for the light emitting layer 4 will be described later. As described above, the metal-doped molybdenum oxide layer is preferably provided in contact with the layer containing a polymer compound. In this embodiment, the polymer compound provided in contact with the metal-doped molybdenum oxide layer is The light emitting layer 4 corresponds to the layer to be included.

  The electron injection layer 5 is provided mainly for improving the efficiency of electron injection from the cathode 3, and can be formed by applying a layer forming coating solution on the surface of the light emitting layer 4 and then drying it. The layer-forming coating solution used when forming the electron injection layer 5 is obtained by dissolving an alkali metal salt. That is, the electron injection layer 5 formed using the layer forming coating solution is configured to contain an alkali metal salt. The layer forming coating solution contains at least an alkali metal salt, but may contain a material different from the alkali metal salt. Examples of the material different from the alkali metal salt contained in the layer forming coating solution include a conductive organic compound and a thickening stabilizer. In addition, the electron injection layer 5 may be substantially composed only of an alkali metal salt.

  The alkali metal salt is at least one salt selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium, and among these, at least selected from the group consisting of sodium, potassium, cesium, lithium is preferable. One type of salt, most preferably a cesium salt. Since the work function of the alkali metal is low, the electron injection layer 5 formed using the layer forming coating solution facilitates electron injection from the cathode 3. Thereby, the drive voltage of the organic EL element 1 can be lowered.

The alkali metal salt is preferably at least one salt selected from the group consisting of molybdic acid, tungstic acid, tantalum acid, niobic acid, vanadate acid, titanic acid, and zinc acid. Examples of the alkali metal salt include general formulas M ₂ MoO ₄ , M ₂ WO ₄ , M ₂ Ta ₂ O ₆ , M ₂ Nb ₂ O ₆ , M ₃ VO ₄ , M ₂ V ₂ O ₆ , M ₂ TiO ₃ , Mention may be made of salts represented by M ₂ ZnO ₂ (wherein M represents an alkali metal). Specifically, lithium molybdate, lithium tungstate, lithium vanadate, lithium niobate, lithium tantalate, lithium titanate, lithium zincate, sodium molybdate, sodium tungstate, sodium vanadate, sodium niobate, tantalate Sodium, sodium titanate, sodium zincate, potassium molybdate, potassium tungstate, potassium vanadate, potassium niobate, potassium tantalate, potassium titanate, potassium zincate, rubidium molybdate, rubidium tungstate, rubidium vanadate, Rubidium niobate, rubidium tantalate, rubidium titanate, rubidium zincate, cesium molybdate, cesium tungstate, cesium vanadate, Obusan cesium, tantalum cesium, cesium titanate, zinc cesium. The alkali metal salt may be a salt of one or more kinds of alkali metals and one or more kinds of acids, such as lithium sodium tungstate molybdate, sodium cesium niobate molybdate, cesium vanadate tantalate, etc. Can be mentioned. Further, the alkali metal salt is preferably a cesium salt, for example, at least one cesium salt selected from the group consisting of molybdic acid, tungstic acid, tantalic acid, niobic acid, vanadium acid, and titanic acid. Can do. Among these, cesium molybdate (Cs ₂ MoO ₄ ) is preferable as the alkali metal salt. By forming the electron injection layer 5 containing cesium molybdate, the driving voltage of the organic EL element 1 is effectively reduced. be able to. Further, since the alkali metal salt is less reactive than the alkali metal alone, it is possible to form the electron injection layer 5 having a small change with time by using the layer forming coating solution.

  The solvent for the layer-forming coating solution may be any solvent that dissolves the alkali metal salt described above, and preferably contains alcohol and / or water.

  The layer forming coating solution preferably further contains a surfactant. Since the surface tension of the layer-forming coating solution is reduced by this surfactant, the wettability with respect to the layer to which the layer-forming coating solution is applied (in this embodiment, the light emitting layer 4) is improved, and the layer-forming coating solution is used. The layer thickness of the formed layer (in this embodiment, the electron injection layer 5) can be made uniform. Examples of such surfactants include anionic surfactants, cationic surfactants, zwitterionic (amphoteric) surfactants, and nonionic surfactants. Specifically, Polyalkyl alcohol alkyl ether, polyhydric alcohol alkyl ester, polyoxyethylene alkyl ether, polyoxyethylene alkyl ester, polyoxypropylene alkyl ether, polyoxypropylene alkyl ester, and acetylene glycol, or hydrogen of these alkyl groups Mention may be made of fluorine-based nonionic surfactants in which at least some of the atoms are replaced by fluorine atoms. The higher the wettability of the layer-forming coating solution with respect to the layer to be applied (in this embodiment, the light emitting layer 4), the more uniform the layer thickness is, and it is preferable that the substrate (hereinafter referred to as PET) made of polyethylene naphthalate. It is preferable that the contact angle of the layer forming coating solution with respect to the substrate) is 60 ° or less. By using such a layer-forming coating solution that exhibits a contact angle with respect to the PET substrate, a flat layer (in the present embodiment, the electron injection layer 5) having a small surface roughness can be formed.

  The layer-forming coating solution is obtained by dissolving the alkali metal salt described above in a solvent such as the alcohol and / or water described above. As described above, a surfactant may be further added. The layer-forming coating solution may be any liquid that deposits an alkali metal salt when the layer-forming coating solution is dried, and need not be obtained by dissolving the alkali metal salt.

  As a method of applying the layer forming coating solution on the surface of the light emitting layer 4, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method. Coating methods such as slit coating, capillary coating, spray coating, nozzle coating, etc., gravure printing, screen printing, flexographic printing, offset printing, reverse printing, inkjet printing, etc. are used. be able to. The gravure printing method, the screen printing method, the flexographic printing method, the offset printing method, the reverse printing method, and the ink jet printing method are preferable in that pattern formation and multicolor coating are easy.

  The layer thickness of the electron injection layer 5 varies depending on the material used, and is selected so that the driving voltage and the light emission efficiency are appropriate values. At least a thickness that does not cause pinholes is required. Too much is not preferable because the driving voltage of the element increases. Therefore, the film thickness of the electron injection layer 5 is usually 1 nm to 1 μm. Preferably it is 2 nm-500 nm, More preferably, it is 3 nm-200 nm.

  The layer forming coating solution may be used not only as the electron injection layer 5 described above but also as a coating solution for forming the cathode. The electron injection layer 5 does not need to be provided in contact with the cathode 3, and a layer different from the electron injection layer 5 may be inserted between the electron injection layer 5 and the cathode 3. A layer different from the electron injection layer 5 may be inserted between the injection layer 5 and the light emitting layer 4. Furthermore, since the layer formed by the layer-forming coating solution improves the charge injection property, it can be used as an electrode such as an organic solar cell and an organic transistor, or a layer between the electrode and the organic material.

  The layer forming coating solution preferably has a hydrogen ion index of 7 or more and 13 or less. If such a layer-forming coating solution is used, for example, a layer containing an alkali metal salt can be formed by coating the layer-forming coating solution on a film that is easily dissolved in an acidic solution. For example, when a layer containing an alkali metal salt is formed on an electrode made of ITO that is easily dissolved in an acidic solution, a layer-forming coating solution can be suitably used.

  The cathode 3 preferably has a small work function and can easily inject electrons into the light emitting layer 4, and has a high electrical conductivity. In addition, when light is extracted from the anode 2 side, a material having a high visible light reflectance is preferable in order to reflect light from the light emitting layer 4 to the anode 2 side. The material of the cathode 3 will be described later.

  The organic EL element of the present embodiment has the layer configuration shown in FIG. 1, but the layer configuration of the organic EL element to which the present invention is applicable is not limited to the layer configuration shown in FIG. The layer structure that the organic EL element to which the present invention can be applied will be described below.

  The organic EL element of this embodiment has an anode, a metal-doped molybdenum oxide layer, a light emitting layer, a layer formed by a coating method using a layer-forming coating solution in which an alkali metal salt is dissolved, and a cathode. In addition, another layer may be provided between the anode and the light emitting layer and / or between the light emitting layer and the cathode.

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

The electron injection layer is a layer having a function of improving electron injection efficiency from the cathode, and the electron transport layer is a layer having a function of improving electron injection from the cathode, the electron injection layer or the electron transport layer closer to the cathode. is there. The hole blocking layer is an electron injection layer or a layer having a function of blocking the hole transport by the electron transport layer. Note that the electron injection layer or the electron transport layer may also serve as the hole blocking layer. Having the function of blocking hole transport makes it possible, for example, to produce an element that allows only hole current to flow, and confirm the blocking effect by reducing the current value.
In the present embodiment, the layer formed by the coating method using the layer forming coating solution in which the alkali metal salt is dissolved is described as the electron injection layer. However, in another embodiment, the alkali metal salt is dissolved. A layer-forming coating in which an electron injection layer different from the layer formed by a coating method using a layer-forming coating solution is provided, and an alkali metal salt that functions as a hole transport layer is dissolved between the electron injection layer and the light-emitting layer A layer formed by a coating method using a liquid may be provided.

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

  The hole injection layer is a layer having a function of improving the hole injection efficiency from the anode, and the hole transport layer is a hole injection layer from the anode, the hole injection layer or the hole transport layer closer to the anode. It is a layer having a function of improving. The electron blocking layer is a hole injection layer or a layer having a function of blocking the electron transport by the hole transport layer. The hole injection layer or the hole transport layer may also serve as the electron blocking layer. Having the function of blocking electron transport makes it possible, for example, to manufacture an element that allows only electron current to flow and to confirm the blocking effect by reducing the current value.

  In the organic EL element of the present embodiment, the layer configuration between the anode 2 and the cathode 3 is not limited to the layer configuration of the organic EL element 1 described above. Although one light emitting layer is usually provided, the present invention is not limited to this, and two or more light emitting layers may be provided. In that case, two or more light-emitting layers can be stacked in direct contact with each other, and the metal-doped molybdenum oxide layer of this embodiment can be provided between the layers.

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

An example of the layer structure that can be taken by the organic EL element to which the present invention can be applied is shown below.
a) Anode / hole injection layer / emission layer / electron injection layer / cathode b) Anode / hole injection layer / emission layer / electron transport layer / cathode c) Anode / hole injection layer / emission layer / electron transport layer / Electron injection layer / cathode d) anode / hole transport layer / light emitting layer / electron injection layer / cathode e) anode / hole transport layer / light emitting layer / electron transport layer / cathode f) anode / hole transport layer / light emitting layer / Electron transport layer / electron injection layer / cathode g) anode / hole injection layer / hole transport layer / light emitting layer / electron injection layer / cathode h) anode / hole injection layer / hole transport layer / light emitting layer / electron Transport layer / cathode i) Anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode (here, the symbol “/” is the two layers sandwiching the symbol “/”) Are adjacent to each other, and so on.

  In each example of the layer configuration, the metal-doped molybdenum oxide layer is provided as at least one of a charge injection layer and a hole transport layer. The layer formed using the layer forming coating solution is provided as at least one of an electron injection layer and an electron transport layer.

Furthermore, the organic EL element may have two or more light emitting layers. As an organic EL element having two light emitting layers, in any one of the layer configurations of the above a) to i), when a laminate sandwiched between an anode and a cathode is referred to as “repeating unit A”, The layer configuration shown in j) below can be given.
j) Anode / (Repeating Unit A) / Charge Injection Layer / (Repeating Unit A) / Cathode As an organic EL device having three or more light emitting layers, “(Repeating Unit A) / Charge Injection Layer” As the “repeating unit B”, the layer structure shown in the following k) can be exemplified.
k) Anode / (Repeating unit B) x / (Repeating unit A) / Cathode The symbol “x” represents an integer of 2 or more, and (Repeating unit B) x is a laminate in which the repeating unit B is laminated in x stages. Represents the body.
Here, the charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include a thin film made of vanadium oxide, indium tin oxide (abbreviated as ITO), molybdenum oxide, or the like.

  The organic EL element of the present embodiment may be further provided on a substrate, and the respective layers can be provided on the substrate. The organic EL element of the present embodiment may further be provided with a sealing member that sandwiches the organic EL element together with the substrate. The organic EL device having the substrate and the above layer structure usually has a substrate on the anode side, but the present invention is not limited to this, and the substrate may be on either the anode or cathode side.

  In the organic EL element of the present embodiment, in order to emit light from the light emitting layer, generally, either one of the light emitting layers is a light transmissive layer. Specifically, for example, in the case of an organic EL device having a configuration of substrate / anode / charge injection layer / hole transport layer / light emitting layer / electron transport layer / charge injection layer / cathode / sealing member, the substrate, anode, charge All of the injection layer and the hole transport layer are transparent, so as to be a so-called bottom emission type device, or all of the electron transport layer, the charge injection layer, the cathode and the sealing member are light-transmitting layers, A so-called top emission type element can be obtained. In the case of an organic EL device having the structure of substrate / cathode / charge injection layer / electron transport layer / light emitting layer / hole transport layer / charge injection layer / anode / sealing member, the substrate, cathode, charge injection layer and electrons All of the transport layers are transparent, so-called bottom emission type elements, or the hole transport layer, the charge injection layer, the anode and the sealing member are all transparent, so-called top emission type elements. can do. Here, the term “transparent” means that the visible light transmittance from the light emitting layer to the light emitting layer is 40% or more. In the case of an element that requires light emission in the ultraviolet region or infrared region, a device having a transmittance of 40% or more in the region is preferable.

The organic EL device of the present embodiment further includes the charge injection layer or a film thickness of 2 nm or less adjacent to the charge generation layer in order to improve adhesion to the charge generation layer or to improve charge injection from the charge generation layer. An insulating layer may be provided, and a thin buffer layer may be inserted at the interface between the charge transport layer and the light emitting layer in order to improve adhesion at the interface or prevent mixing.
The order and number of layers to be laminated, and the thickness of each layer can be appropriately used in consideration of light emission efficiency and element lifetime.

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

<Board>
The substrate used in the organic EL element of this embodiment may be any substrate that does not change when an electrode is formed and an organic layer is formed. For example, glass, plastic, polymer film, silicon substrate, and these are laminated. Used. A commercially available substrate is available as the substrate, or can be manufactured by a known method.

<Anode>
As the anode in the organic EL element of the present embodiment, it is preferable to use a transparent or translucent electrode because an element that emits light through the anode can be configured. As such a transparent electrode or a semi-transparent electrode, a metal oxide, metal sulfide or metal thin film having high electrical conductivity can be used, and a high transmittance can be suitably used. And use. Specifically, indium oxide, zinc oxide, tin oxide, ITO, indium zinc oxide (IZO), gold, platinum, silver, copper, and the like are used, and ITO, IZO, and tin oxide are preferable. Examples of the production method include a vacuum deposition method, a sputtering method, an ion plating method, a plating method, and the like. Further, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used as the anode.
A material that reflects light may be used for the anode, and the material is preferably a metal, metal oxide, or metal sulfide having a work function of 3.0 eV or more. For example, a metal thin film having a thickness that reflects light is used.

  Examples of a method for producing the anode include a vacuum deposition method, a sputtering method, an ion plating method, and a plating method. Further, as the anode 2, an organic transparent conductive film such as polyaniline or a derivative thereof, polythiophene or a derivative thereof may be used. Moreover, you may use the mixture containing at least 1 or more types of carbon materials, such as the material used for the said organic transparent conductive film, carbon nanotubes, such as a metal oxide, a metal sulfide, and a metal.

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

<Hole injection layer>
In a particularly preferred embodiment of the present invention, the metal-doped molybdenum oxide layer can be used as the hole injection layer, and can be formed by the above-described method, but the layer is different from the metal-doped molybdenum oxide layer. When forming a hole injection layer, the material for forming the hole injection layer includes phenylamine, starburst amine, phthalocyanine, vanadium oxide, tantalum oxide, tungsten oxide, molybdenum oxide, ruthenium oxide, and oxide. Examples thereof include oxides such as aluminum, amorphous carbon, polyaniline, and polythiophene derivatives.
Examples of the method for forming the hole injection layer include film formation from a solution containing a hole injection material. The solvent used for film formation from a solution is not particularly limited as long as it dissolves the hole injection material. Chlorine solvents such as chloroform, methylene chloride, dichloroethane, ether solvents such as tetrahydrofuran, toluene, xylene And aromatic hydrocarbon solvents such as acetone, ketone solvents such as acetone and methyl ethyl ketone, ester solvents such as ethyl acetate, butyl acetate and ethyl cellosolve acetate, and water.
As a film forming method from a solution, a spin coating method, a casting method, a micro gravure coating method, a gravure coating method, a bar coating method, a roll coating method, a wire bar coating method, a dip coating method, a spray coating method, a screen printing method, Examples of the application method include a flexographic printing method, an offset printing method, and an ink jet printing method.
The film thickness of the hole injection layer varies depending on the material used, and is set as appropriate so that the drive voltage and light emission efficiency are appropriate. If it is thick, the driving voltage of the element increases, which is not preferable. Therefore, the film thickness of the hole injection layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, and more preferably 5 nm to 200 nm.

<Hole transport layer>
A metal-doped molybdenum oxide layer can also be used as the hole transport layer and can be formed by the above-described method. However, when the hole transport layer is formed of a layer different from the metal-doped molybdenum oxide layer, Examples of the material constituting the hole transport layer include N, N′-diphenyl-N, N′-di (3-methylphenyl) 4,4′-diaminobiphenyl (TPD), NPB (4,4′-bis [ Aromatic amine derivatives such as N- (1-naphthyl) -N-phenylamino] biphenyl), polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amines in the side chain or main chain, pyrazoline derivatives, Arylamine derivatives, stilbene derivatives, triphenyldiamine derivatives, polyaniline or Examples thereof include polythiophene or a derivative thereof, polyarylamine or a derivative thereof, polypyrrole or a derivative thereof, poly (p-phenylene vinylene) or a derivative thereof, or poly (2,5-thienylene vinylene) or a derivative thereof. .

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

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

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

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

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

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

<Light emitting layer>
In the present invention, the light emitting layer is preferably an organic light emitting layer, and usually contains an organic substance that mainly emits fluorescence or phosphorescence. Further, a dopant material may be further included. Examples of the material for forming the light emitting layer that can be used in the present invention include the following. The organic substance may be a low molecular compound or a high molecular compound, and the light emitting layer preferably contains a high molecular compound having a polystyrene-equivalent number average molecular weight of 10 ³ to 10 ⁸ .

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

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

(Polymer material)
Polymeric materials include polyparaphenylene vinylene derivatives, polythiophene derivatives, polyparaphenylene derivatives, polysilane derivatives, polyacetylene derivatives, polyfluorene derivatives, polyvinylcarbazole derivatives, and polymerized chromophores and metal complex light emitting materials. Etc.
Among the light-emitting materials, examples of materials that emit blue light include distyrylarylene derivatives, oxadiazole derivatives, and polymers thereof, polyvinylcarbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives. Of these, polymer materials such as polyvinyl carbazole derivatives, polyparaphenylene derivatives, and polyfluorene derivatives are preferred.
Examples of materials that emit green light include quinacridone derivatives, coumarin derivatives, and polymers thereof, polyparaphenylene vinylene derivatives, polyfluorene derivatives, and the like. Of these, polymer materials such as polyparaphenylene vinylene derivatives and polyfluorene derivatives are preferred.
Examples of materials that emit red light include coumarin derivatives, thiophene ring compounds, and polymers thereof, polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives. Among these, polymer materials such as polyparaphenylene vinylene derivatives, polythiophene derivatives, and polyfluorene derivatives are preferable.

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

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

<Electron transport layer>
A layer formed by the above-described coating method using a layer-forming coating solution in which an alkali metal salt is dissolved can be used as the electron transport layer, and the layer-forming coating solution in which an alkali metal salt is dissolved can be formed by the method described above. In the case where the electron transport layer is composed of a layer different from the layer formed by the coating method using, a known material can be used as the material of the electron transport layer, and an oxadiazole derivative, anthraquinodimethane or Derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinones or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, diphenyldicyanoethylene or derivatives thereof, diphenoquinone derivatives, or 8-hydroxyquinoline or derivatives thereof Metal complex , Polyquinoline or derivatives thereof, polyquinoxaline or derivatives thereof, polyfluorene or derivatives thereof, and the like.

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

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

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

<Electron injection layer>
A layer formed by the above-described coating method using a layer-forming coating solution in which an alkali metal salt is dissolved can also be used as the electron injection layer, and can be formed by the above-described method, but a layer-forming coating in which an alkali metal salt is dissolved When the electron injection layer is composed of a layer different from the layer formed by a coating method using a liquid, the material constituting the electron injection layer is an alkali metal or alkaline earth metal depending on the type of the light emitting layer. Or an alloy containing one or more kinds of the metals, oxides, halides and carbonates of the metals, or mixtures of the substances. Examples of alkali metals or oxides, halides, and carbonates thereof include 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 alkaline earth metals or oxides, halides and carbonates thereof include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, barium fluoride, Examples include strontium oxide, strontium fluoride, and magnesium carbonate. The electron injection layer may be a laminate of two or more layers. Specifically, LiF / Ca etc. are mentioned. The electron injection layer is formed by vapor deposition, sputtering, printing, or the like. The thickness of the electron injection layer is preferably about 1 nm to 1 μm.

<Cathode>
As a material for the cathode, a material having a small work function and easy electron injection into the light emitting layer, a material having high electric conductivity and high visible light reflectance is preferable. As the metal, an alkali metal, an alkaline earth metal, a transition metal, or a group 13 metal in the periodic table can be used. For example, a metal such as lithium, sodium, potassium, rubidium, cesium, beryllium, magnesium, calcium, strontium, barium, aluminum, scandium, vanadium, zinc, yttrium, indium, cerium, samarium, europium, terbium, ytterbium, or the above metal Or an alloy of one or more of them with one or more of gold, silver, platinum, copper, manganese, titanium, cobalt, nickel, tungsten, tin, or a graphite or graphite layer A compound or the like is used. Examples of the alloy include magnesium-silver alloy, magnesium-indium alloy, magnesium-aluminum alloy, indium-silver alloy, lithium-aluminum alloy, lithium-magnesium alloy, lithium-indium alloy, calcium-aluminum alloy, and the like. Moreover, a transparent conductive electrode can be used as a cathode, for example, a conductive metal oxide, a conductive organic substance, etc. can be used. Specifically, indium oxide, zinc oxide and tin oxide as conductive metal oxides, and ITO and IZO which are composites thereof, and organic transparent conductive materials such as polyaniline or derivatives thereof, polythiophene or derivatives thereof as conductive organic substances. A membrane may be used. Note that the cathode may have a laminated structure of two or more layers. In some cases, the electron injection layer is used as a cathode.

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

  As a method for producing the cathode, a vacuum deposition method, a sputtering method, a laminating method for bonding a metal thin film, or the like is used.

<Insulating layer>
An insulating layer having a thickness of 2 nm or less that the organic EL element of this embodiment can optionally have has a function of facilitating charge injection. Examples of the material for the insulating layer include metal fluorides, metal oxides, and organic insulating materials. Organic EL elements having an insulating layer having a thickness of 2 nm or less are provided with an insulating layer having a thickness of 2 nm or less adjacent to the cathode, and those having an insulating layer having a thickness of 2 nm or less adjacent to the anode. Can be mentioned.

  The organic EL element of this embodiment can be used for a planar light source, a display device such as a segment display device, a dot matrix display device, a liquid crystal display device, and an illumination device. It can also be used as a light source for a scanner.

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

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

  As described above, the organic EL device according to the present invention forms a layer by a coating method using a layer forming coating solution in which an alkali metal salt is dissolved. Compared to the technology, it is not necessary to create a vacuum atmosphere, the layer can be formed easily, and the manufacturing cost of the organic EL element can be reduced. In particular, when an electron injection layer in contact with the cathode is formed using a layer forming coating solution obtained by dissolving an alkali metal salt, the driving voltage of the organic EL element can be lowered.

  In addition, since the metal-doped molybdenum oxide layer has high resistance to wet processes, even if a light emitting layer and an electron injection layer are formed thereon by a wet process, the metal-doped molybdenum oxide layer is not damaged so easily. A highly reliable organic EL device can be easily manufactured by a wet process of a simple process, and its light emission characteristics and lifetime characteristics are good.

  Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited thereto. In Examples 1 to 11 and Comparative Example 1, a layer-forming coating solution for forming a layer between the light-emitting layer and the cathode was prepared, and an organic EL device in which an electron injection layer was formed with this layer-forming coating solution was produced. It was confirmed that light was emitted. Moreover, in Examples 12-17 and Comparative Examples 2-3, the organic EL element which has a metal dope molybdenum oxide layer was manufactured, and the effect was confirmed.

<Example 1>
Cs ₂ MoO ₄ powder (purity 99.9%, manufactured by Furuuchi Chemical Co., Ltd.) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 10:90 and put into a screw tube. The mixture was stirred and a layer forming coating solution was prepared. It was visually confirmed that the Cs ₂ MoO ₄ powder was completely dissolved. The surface tension of this layer forming coating solution was 58.3 mN / m. Table 1 below shows the results of measuring the contact angles between the prepared layer-forming coating solution and a plurality of types of substrates. When pH (hydrogen ion index) was measured using a pH test paper, it was about 7.
<Example 2>

Cs ₂ MoO ₄ powder (purity 99.9%, manufactured by Furuuchi Chemical Co., Ltd.), ultrapure water (electric resistivity is 15 MΩ · cm or more) and ethanol (purity 99.5%, deer grade 1, manufactured by Kanto Chemical Co., Inc.) ) In a weight ratio of 10:26:63, stirred in a screw tube in the order of Cs ₂ MoO ₄ powder and ultrapure water, and then mixed with ethanol to prepare a layer-forming coating solution. It was visually confirmed that the Cs ₂ MoO ₄ powder was completely dissolved. The surface tension of this layer forming coating solution was 22.6 mN / m. Table 1 below shows the results of measuring the contact angles between the prepared layer-forming coating solution and a plurality of types of substrates. When pH was measured using pH test paper, it was about 8-9.
<Example 3>

Cs ₂ MoO ₄ powder (purity 99.9%, manufactured by Furuuchi Chemical Co., Ltd.), ultrapure water (electric resistivity is 15 MΩ · cm or more) and ethanol (purity 99.5%, deer grade 1, manufactured by Kanto Chemical Co., Inc.) ) And a surfactant (Surfinol (registered trademark) 104A: manufactured by Nissin Chemical Co., Ltd.) are weighed to a weight ratio of 10: 25: 61: 4, and screwed in the order of Cs ₂ MoO ₄ powder and ultrapure water. It stirred in the pipe | tube, ethanol was mixed after that, surfactant was mixed after that, and the layer formation coating liquid was produced. It was visually confirmed that the Cs ₂ MoO ₄ powder was completely dissolved. The surface tension of this layer forming coating solution was 26.6 mN / m. Table 1 shows the results of measuring contact angles between the prepared layer-forming coating solution and a plurality of types of substrates. When pH was measured using pH test paper, it was about 8-9.
<Example 4>

Cs ₃ VO ₄ powder (purity 99.9%, manufactured by Aldrich) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 1:99, put in a screw tube and stirred. A forming coating solution was prepared. It was confirmed by visual observation that it was completely dissolved. When pH was measured using pH test paper, it was about 7.
<Example 5>

CsVO ₃ powder (purity 99.9%, made by Aldrich) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 1:99, put in a screw tube and stirred to form a layer A forming coating solution was prepared. It was visually confirmed that the CsVO ₃ powder was completely dissolved. When pH was measured using pH test paper, it was about 12.
<Example 6>

CsVO ₃ powder (purity 99.9%, manufactured by Aldrich) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 30:70, and placed in a screw tube and stirred to form a layer. A coating solution was prepared. When the pH of the supernatant was measured using a pH test paper, it was about 13.
<Example 7>

K ₂ MoO ₄ powder (purity 98%, manufactured by Aldrich) and ultrapure water (electrical resistivity of 15 MΩ · cm or more) are weighed to a weight ratio of 1:99, and placed in a screw tube and stirred to form a layer. A coating solution was prepared. It was confirmed by visual observation that it was completely dissolved. When the pH was measured using a pH test paper, it was about 7.5.
<Example 8>

K ₂ MoO ₄ powder (purity 98%, manufactured by Aldrich) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 30:70, put in a screw tube and stirred, A forming coating solution was prepared. When the pH of the supernatant was measured using pH test paper, it was about 9.
<Example 9>

Na ₂ MoO ₄ powder (purity> 98%, manufactured by Aldrich) and ultrapure water (electric resistivity is 15 MΩ · cm or more) are weighed to a weight ratio of 1:99, put in a screw tube, and stirred. A layer forming coating solution was prepared. It was confirmed by visual observation that it was completely dissolved. When pH was measured using pH test paper, it was about 7.
<Example 10>

Na ₂ MoO ₄ powder (purity> 98%, manufactured by Aldrich) and ultrapure water (electrical resistivity of 15 MΩ · cm or more) are weighed to a weight ratio of 30:70, placed in a screw tube and stirred. A forming coating solution was prepared. When the pH of the supernatant was measured using pH test paper, it was about 8.

<Comparative Example 1>
BaMoO ₄ powder (purity> 99.9%, manufactured by Aldrich) and ultrapure water (electrical resistivity of 15 MΩ · cm or more) are weighed to a weight ratio of 1:99, put in a screw tube and stirred to prepare a solution. Produced. It was confirmed by visual observation that the BaMoO ₄ powder was hardly dissolved. When pH was measured using pH test paper, it was about 7.

(Measurement method of surface tension and contact angle)
A measuring device of model number OCA-20 manufactured by Data Physics (Germany) was used for the measurement. Surface tension is measured by first filling the syringe with a solution, attaching a metal needle with an outer diameter of 1.4 mm to the syringe, removing the solution from the metal needle, and analyzing the image of the shape immediately before the solution leaves the metal needle. Was done by.

The contact angle was determined by measuring the angle between the surface of the substrate and the surface of the substrate at which the liquid surface of the attached solution was in contact with the surface of the substrate. As the substrate, (1) an untreated non-alkali glass substrate that has not been subjected to UV-O ₃ cleaning, and (2) UV-O ₃ cleaning treatment (equipped with “UV cleaning” in Table 1) using an apparatus manufactured by Technovision. And a non-alkali glass substrate subjected to 10 minutes, and (3) an ITO substrate in which an ITO thin film having a thickness of 150 nm is formed on a glass substrate by a sputtering method, and UV-O ₃ cleaning treatment is not performed. An untreated ITO substrate, (4) an ITO substrate in which an ITO thin film having a thickness of 150 nm is formed by sputtering on a glass substrate that has been subjected to UV-O ₃ cleaning treatment for 10 minutes by an apparatus manufactured by Technovision, (5) Al vapor deposition substrate in which an aluminum thin film having a film thickness of 300 nm is formed on a glass substrate by EB method, (6) Polymer light emitting organic material (SCB670, manufactured by Summation) Each of the substrates was formed using a spin coating method on a glass substrate and a polymer spin film formation substrate on which a polymer with a film thickness of 80 nm was formed, and (7) a PEN substrate made of polyethylene naphthalate (PEN). On the other hand, the contact angle with the layer formation coating liquid produced in Examples 1-3 was measured.

  Table 1 shows the measurement results of contact angles between the layer-forming coating solutions of Examples 1 to 3 and a plurality of types of substrates.

As shown in Examples 1 to 10, a layer-forming coating solution in which an alkali metal salt was dissolved could be prepared. Further, as shown in Examples 2 and 3, a layer-forming coating solution having a low surface tension and a small contact angle could be obtained by adding alcohol or a surfactant to ultrapure water.
<Example 11>

  An organic EL element was produced using the layer-forming coating solution produced in Example 3. The configuration of the organic EL device produced in the examples is glass substrate / anode made of ITO thin film / hole injection layer / electron blocking layer / light emitting layer / electron injection layer / cathode, and this is further sealed with sealing glass did. The electron injection layer was formed using the layer forming coating solution prepared in Example 3.

(Synthesis Example 1)
The polymer compound 1 to be the electron blocking layer was synthesized. First, 2,7-bis (1,3,2-dioxaborolan-2-yl) -9,9- was added to a separable flask equipped with a stirring blade, baffle, length-adjustable nitrogen inlet tube, cooling tube, and thermometer. 158.29 parts by weight of dioctylfluorene, 136.11 parts by weight of bis- (4-bromophenyl) -4- (1-methylpropyl) -benzenamine, 27 weights of tricaprylmethylammonium chloride (Aliquat 336 manufactured by Henkel) And 1800 parts by weight of toluene were added, and the temperature was raised to 90 ° C. with stirring while introducing nitrogen from a nitrogen introduction tube. After adding 0.066 parts by weight of palladium (II) acetate and 0.45 parts by weight of tri (o-toluyl) phosphine, 573 parts by weight of a 17.5% aqueous sodium carbonate solution was added dropwise over 1 hour. After completion of the dropwise addition, the nitrogen inlet tube was lifted from the liquid surface and kept under reflux for 7 hours, then 3.6 parts by weight of phenylboric acid was added, kept under reflux for 14 hours, and cooled to room temperature. After removing the reaction solution aqueous layer, the reaction solution oil layer was diluted with toluene and washed with 3% acetic acid aqueous solution and ion-exchanged water. After adding 13 parts by weight of sodium N, N-diethyldithiocarbamate trihydrate to the separated oil layer and stirring for 4 hours, the solution was passed through a mixed column of activated alumina and silica gel, and toluene was passed through to wash the column. did. The filtrate and washings were mixed and then added dropwise to methanol to precipitate the polymer. The obtained polymer precipitate was separated by filtration, washed with methanol, and then dried with a vacuum dryer to obtain 192 parts by weight of polymer. The resulting polymer is referred to as polymer compound 1. The polymer compound 1 had a polystyrene equivalent weight average molecular weight of 3.7 × 10 ⁵ and a number average molecular weight of 8.9 × 10 ⁴ .

(GPC analysis method)
The polystyrene equivalent weight average molecular weight and number average molecular weight were determined by gel permeation chromatography (GPC). Standard polystyrene made by Polymer Laboratories was used to prepare a GPC calibration curve. The polymer to be measured was dissolved in tetrahydrofuran to a concentration of about 0.02% by weight, and 10 μL was injected into GPC. The GPC apparatus used was LC-10ADvp manufactured by Shimadzu Corporation. As the column, two PLgel 10 μm MIXED-B columns (300 × 7.5 mm) manufactured by Polymer Laboratories were used in series, and tetrahydrofuran was flowed at 25 ° C. and a flow rate of 1.0 mL / min as a mobile phase. Absorbance at 228 nm was measured using a UV detector as the detector.

  A glass substrate was used as the substrate. An ITO thin film formed on the surface of the glass substrate by sputtering and patterned into a predetermined shape was used as the anode. The thickness of the ITO thin film was about 150 nm.

  A suspension of poly (3,4) ethylenedioxythiophene / polystyrene sulfonic acid (manufactured by HC Starck B-Tech, trade name: Bytron P / TP AI 4083) is filtered through a 0.5 μm filter to form an ITO thin film. The liquid filtered on the glass substrate was applied by spin coating to form a film with a thickness of 60 nm. Next, the film formed on the extraction electrode portion and the sealing area was wiped off and further dried at about 200 ° C. for 10 minutes using a hot plate in the atmosphere to form a hole injection layer.

  Next, the coating liquid containing the polymer compound 1 was applied to the substrate on which the hole injection layer was formed by a spin coating method to form a film with a thickness of about 20 nm. Next, the film formed on the extraction electrode portion and the sealing area was wiped off and further baked at 200 ° C. for 20 minutes using a hot plate in a nitrogen atmosphere to form an electronic block layer.

  Next, a polymer light-emitting organic material (BP361: manufactured by Summation Co., Ltd.) was applied to the substrate on which the electron blocking layer was formed by spin coating to form a film with a thickness of about 70 nm. Next, the film | membrane formed in the extraction electrode part and the sealing area was wiped off and baked, and the light emitting layer was formed.

Next, the layer-forming coating solution prepared in Example 3 was applied to the substrate on which the light-emitting layer had been formed by spin coating, and the film was formed to a thickness of 2 nm to form an electron injection layer. Next, the film | membrane formed in the extraction electrode part and the sealing area was wiped off and removed, and this board | substrate was moved to the heating chamber of the vacuum evaporation machine (Small-ELVESS) by Tokki Co., Ltd. (After that, the process is performed in vacuum or in nitrogen, and the device is not exposed to the atmosphere during the process.) Next, the substrate is heated to a substrate temperature of about 80 in a vacuum with a degree of vacuum of 1 × 10 ⁻⁴ Pa or less. Heated at ˜120 ° C. for 20 minutes.

After that, the substrate is moved to the vapor deposition chamber, the metal mask for the cathode is aligned so that the cathode is formed on the light emitting part and the extraction electrode part, and both are rotated without changing the relative position of the metal mask and the substrate. The cathode was deposited while The degree of vacuum in the chamber before the start of vapor deposition was 3 × 10 ⁻⁵ Pa or less. As a vapor deposition method, an electron beam vapor deposition method was used, and Al was formed at a vapor deposition rate of about 10 Å / sec to form a cathode having a thickness of 100 nm. Thereafter, a sealing glass in which a UV (ultraviolet) curable resin was applied to the peripheral portion of the surface was bonded to the substrate in an inert gas under reduced pressure. Thereafter, the pressure was returned to atmospheric pressure, and UV (ultraviolet) curable resin was photocured by irradiating UV, thereby fixing the sealing glass to the substrate, and a polymer organic EL device was produced. The light emitting area of one pixel is 2 mm × 2 mm.

(Evaluation of organic EL elements)
Current-voltage-luminance and emission spectrum were measured using an organic EL measuring device manufactured by Tokyo System Development. When a voltage of about 12 V was applied to the organic EL device produced in this example, the front luminance was 1000 cd / m ² . The current density at this time was 0.088 A / cm ² , and the EL emission spectrum showed a peak at 460 nm. As described above, it was confirmed that the organic EL device including the electron injection layer formed by the coating method using the layer forming coating solution emits light.

<Example 12>
(1-1: Deposition of Al-doped MoO ₃ on a glass substrate by vacuum deposition)
A plurality of glass substrates were prepared, one side of which was partially covered with a vapor deposition mask, and attached to the vapor deposition chamber using a substrate holder.
MoO ₃ powder (manufactured by Aldrich, purity 99.99%) was packed in a tungsten board for a box-type sublimation substance, covered with a cover with holes so that the material would not scatter, and set in a vapor deposition chamber. Al (manufactured by Koyo Chemical Co., Ltd., purity 99.999%) was put in a crucible and set in a vapor deposition chamber.
The degree of vacuum in the vapor deposition chamber is set to 3 × 10 ⁻⁵ Pa or less, MoO ₃ is gradually heated by a resistance heating method and sufficiently degassed, and Al is dissolved in a crucible by an electron beam and sufficiently degassed. After performing, it used for vapor deposition. The degree of vacuum during vapor deposition was 9 × 10 ⁻⁵ Pa or less. The film thickness and the deposition rate were constantly monitored with a crystal resonator. When the deposition rate of MoO ₃ reached about 2.8 約 / sec and the deposition rate of Al reached about 0.1 Å / sec, the main shutter was opened and film formation on the substrate was started. During deposition, the substrate was rotated so that the film thickness was uniform. Film formation was carried out for about 36 seconds while controlling the vapor deposition rate to the above speed, and a substrate provided with a co-deposited film having a film thickness of about 100 mm was obtained. The composition ratio of Al to the total of MoO ₃ and Al in the film was about 3.5 mol%.

(1-2: Durability test)
After film formation, the obtained substrate was taken out into the atmosphere and the film surface was observed with an optical microscope (500 times). As a result, it was confirmed that the crystal structure was not observed and the film was in an amorphous state.
When the obtained substrate was exposed to pure water for 1 minute and observed again with an optical microscope, there was no change and the surface was not dissolved. In either case, the substrate was further exposed to pure water for 3 minutes, or the film was wiped with a non-woven fabric (trade name “Bencot”, manufactured by Ozu Sangyo Co., Ltd.) containing pure water and then visually observed. The membrane remained unchanged.
When another substrate obtained was exposed to acetone for 1 minute and observed with an optical microscope, there was no change and the surface was not dissolved. The substrate was further exposed to acetone for 3 minutes, or the film was wiped with a non-woven fabric containing acetone and visually confirmed. In either case, the film remained unchanged.

(1-3: Measurement of transmittance)
Further, the transmittance of the deposited film after film formation was measured using a transmittance / reflectance measuring apparatus FilmTek 3000 (trade name, manufactured by Scientific Computing International). The results are shown in Table 2. The transmission spectrum rose from a wavelength of about 300 nm. The transmittance at a wavelength of 320 nm was 21.6%, and the transmittance at 360 nm was 56.6%. Compared to Comparative Example 2 described later, the transmittance was 3.6 times at 320 nm and 1.6 times at 360 nm.

<Example 13>
A substrate on which a co-deposited film was provided was obtained in the same manner as in Example 1-1 (1-1) except that oxygen was introduced into the chamber during the deposition. The amount of oxygen was controlled to 15 sccm by a mass flow controller. The degree of vacuum during vapor deposition was about 2.3 × 10 ⁻³ Pa. The thickness of the obtained co-deposited film was about 100 mm, and the composition ratio of Al to the total of MoO ₃ and Al in the film was about 3.5 mol%.

  After film formation, the durability of the obtained substrate was evaluated in the same manner as in Example 12 (1-2). No change was observed when exposed to either pure water or acetone.

<Example 14>
The vapor deposition rate was controlled in the same manner as in (1-1) of Example 12 except that the deposition rate was controlled to about 3.7 Å / sec for MoO _{3 and} about 0.01 Å / sec for Al, and a co-deposition film was provided. Obtained substrate. The thickness of the obtained co-deposited film was about 100 mm, and the composition ratio of Al to the total of MoO ₃ and Al in the film was about 1.3 mol%.

  After film formation, the durability of the obtained substrate was evaluated in the same manner as in Example 12 (1-2). No change was observed when exposed to either pure water or acetone.

<Example 15>
The substrate obtained in (1-1) of Example 12 was placed in a clean oven in an air atmosphere and heat-treated at 250 ° C. for 60 minutes. After cooling, the transmittance of the deposited film was measured in the same manner as in Example 1-3 (1-3). The results are shown in Table 2. The transmittance at a wavelength of 320 nm was 28.9%, and the transmittance at 360 nm was 76.2%. Compared to Comparative Example 1 described later, the transmittance was 4.7 times at 320 nm and 2.2 times at 360 nm.

<Comparative example 2>
The same operation as in Example 12 was carried out except that only MoO ₃ was deposited at a rate of about 2.8 liters / second without depositing Al to obtain a substrate provided with a deposited film having a thickness of about 100 liters.
After film formation, the obtained substrate was taken out into the atmosphere and the film surface was observed with an optical microscope (500 times). As a result, it was confirmed that the crystal structure was not observed and the film was in an amorphous state.
When the obtained substrate was exposed to pure water for 1 minute and observed again with an optical microscope, it was observed that a bleeding pattern was observed and the surface was melted. The substrate was further exposed to pure water for 3 minutes, or the film was wiped with a non-woven fabric soaked with pure water and visually observed. In all cases, the film disappeared.
Another obtained substrate was exposed to acetone for 1 minute and observed with an optical microscope. As a result, a bleeding pattern was observed and the surface was melted. The substrate was further exposed to acetone for 3 minutes, or the film was wiped with a non-woven fabric containing acetone and then visually confirmed. In all cases, the film was lost.
Moreover, the transmittance | permeability of the vapor deposition film after film-forming was measured similarly to (1-3) of Example 12. FIG. The results are shown in Table 2. The transmittance at a wavelength of 320 nm was 6.1%, the transmittance at 360 nm was 35.4%, and it was confirmed that the transmittance was low.

(Synthesis Example 2)
2,7-bis (1,3,2-dioxaborolan-2-yl) -9,9-dioctyl was added to a separable flask equipped with a stirring blade, baffle, length-adjustable nitrogen inlet tube, cooling tube, and thermometer. 158.29 parts by weight of fluorene, 136.11 parts by weight of bis- (4-bromophenyl) -4- (1-methylpropyl) -benzenamine, 27 parts by weight of tricaprylmethylammonium chloride (Aliquat 336 manufactured by Henkel), toluene 1800 parts by weight were charged, and the temperature was raised to 90 ° C. with stirring while flowing nitrogen from the nitrogen introduction tube. After adding 0.066 parts by weight of palladium (II) acetate and 0.45 parts by weight of tri (o-toluyl) phosphine, 573 parts by weight of a 17.5% aqueous sodium carbonate solution was added dropwise over 1 hour. After completion of the dropwise addition, the nitrogen inlet tube was lifted from the liquid surface and kept under reflux for 7 hours, then 3.6 parts by weight of phenylboric acid was added, kept under reflux for 14 hours, and cooled to room temperature. After removing the reaction solution aqueous layer, the reaction solution oil layer was diluted with toluene and washed with 3% acetic acid aqueous solution and ion-exchanged water. 13 parts by weight of sodium N, N-diethyldithiocarbamate trihydrate was added to the separated oil layer, stirred for 4 hours, and then passed through a mixed column of activated alumina and silica gel, and toluene was passed through to wash the column. . The filtrate and washings were mixed and then added dropwise to methanol to precipitate the polymer. The obtained polymer precipitate was separated by filtration, washed with methanol, and then dried with a vacuum dryer to obtain 192 parts by weight of polymer. The resulting polymer is referred to as polymer compound 1. When the polystyrene equivalent weight average molecular weight and number average molecular weight of the polymer compound 1 were determined by the following GPC analysis method, the polystyrene equivalent weight average molecular weight was 3.7 × 10 ⁵ and the number average molecular weight was 8.9 × 10 ⁴ . .

(GPC analysis method)
The polystyrene equivalent weight average molecular weight and number average molecular weight were determined by gel permeation chromatography (GPC). Standard polystyrene made by Polymer Laboratories was used to prepare a GPC calibration curve. The polymer to be measured was dissolved in tetrahydrofuran to a concentration of about 0.02% by weight, and 10 μL was injected into the GPC apparatus.
The GPC apparatus used was LC-10ADvp manufactured by Shimadzu Corporation. As the column, two PLgel 10 μm MIXED-B columns (300 × 7.5 mm) manufactured by Polymer Laboratories were used in series, and tetrahydrofuran was flowed at 25 ° C. and a flow rate of 1.0 mL / min as a mobile phase. The detector used a UV detector to measure the absorbance at 228 nm.

<Example 16>
(Production of organic EL element)
A glass substrate having an ITO thin film patterned on the surface was used as the substrate, and an Al-doped MoO ₃ layer having a thickness of 100 mm was deposited on the ITO thin film by a vacuum deposition method in the same manner as in Example 13.
After the film formation, the substrate was taken out into the atmosphere, and the polymer compound 1 obtained in Synthesis Example 1 was formed on the deposited film by spin coating to form an interlayer layer having a thickness of 20 nm. The interlayer layer formed on the extraction electrode portion and the sealing area was removed, and baking was performed at 200 ° C. for 20 minutes on a hot plate.

Thereafter, a polymer light-emitting organic material (manufactured by RP158 Summation Co., Ltd.) was formed on the interlayer layer by a spin coating method to form a light-emitting layer having a thickness of 90 nm. The light emitting layer formed on the extraction electrode portion and the sealing area was removed.
The subsequent processes up to the sealing were performed in vacuum or nitrogen so that the elements in the process were not exposed to the atmosphere.

  The substrate was heated at a substrate temperature of about 100 ° C. for 60 minutes in a vacuum heating chamber. Thereafter, the substrate was transferred to a vapor deposition chamber, and a cathode mask was aligned on the surface of the light emitting layer so that a cathode was formed on the light emitting portion and the extraction electrode portion. Further, the cathode was deposited while rotating the mask and the substrate. As a cathode, metal Ba is heated by a resistance heating method and evaporated at a deposition rate of about 2 mm / second and a film thickness of 50 mm, and Al is deposited thereon by an electron beam deposition method at an evaporation rate of about 2 mm / second and a film thickness of 150 nm. Vapor deposition.

Thereafter, the substrate is bonded to a prepared sealing glass coated with UV curable resin around the substrate, kept in vacuum, then returned to atmospheric pressure, fixed by irradiation with UV, and light emitting region Produced a 2 × 2 mm organic EL device. The obtained organic EL device had a layer structure of glass substrate / ITO film / Al-doped MoO ₃ layer / interlayer layer / light emitting layer / Ba layer / Al layer / sealing glass.

(Evaluation of organic EL elements)
The manufactured element was energized so that the luminance was 1000 cd / m ^2, and current-voltage characteristics were measured. In addition, the device was driven at a constant current at 10 mA, light emission was started at an initial luminance of about 2000 cd / m ² , the light emission was continued as it was, and the light emission lifetime was measured. The results are shown in Tables 2 and 3. Compared to Comparative Example 2 described later, the maximum power efficiency is slightly higher, the driving voltage at the time of 1000 cd / m ² emission is reduced, and the life is extended by about 1.6 times.

<Example 17>
An organic EL device was prepared in the same manner as in Example 16 except that an Al-doped MoO ₃ layer was formed in the same procedure as in Example 14, and current-voltage characteristics and emission lifetime were measured. The emission lifetime was measured by driving at a constant current of 10 mA, starting emission at an initial luminance of about 2000 cd / m ² , and then continuing emission. The results are shown in Tables 3 and 4. Compared to Comparative Example 2 described later, the maximum power efficiency is slightly higher, the driving voltage at the time of 1000 cd / m ² emission is reduced, and the life is extended about 2.4 times.

<Comparative Example 3>
Instead of forming the Al-doped MoO ₃ layer, the same procedure as in Comparative Example 2 was followed, except that the MoO ₃ layer was formed in the same manner as in Example 16 to produce an organic EL element, and the current-voltage characteristics The emission lifetime was measured. The emission lifetime was measured by driving at a constant current of 10 mA, starting emission at an initial luminance of about 2000 cd / m ² , and then continuing emission. The results are shown in Tables 3 and 4.

As described above, in Examples 1 to 11 and Comparative Example 1, a layer forming coating solution for forming a layer between the light emitting layer and the cathode was prepared, and an organic layer having a layer formed by this layer forming coating solution was prepared. An EL element was manufactured and its effect was confirmed. In Examples 12 to 17 and Comparative Examples 2 to 3, organic EL elements having a metal-doped molybdenum oxide layer were produced, and the effects were confirmed.
It is clear that the effect of the organic EL element having the layer formed by the layer forming coating solution and the effect of the organic EL element having the metal-doped molybdenum oxide layer are not mutually exclusive, and one organic In the EL element, when the layer formed by the layer forming coating liquid is provided and the metal doped molybdenum oxide layer is provided, the effect of the organic EL element having the layer formed by the layer forming coating liquid, and the metal doping The effect of the organic EL element having a molybdenum oxide layer can be obtained at the same time.

It is a front view which shows the organic EL element by embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Organic EL element 2 Anode 3 Cathode 4 Light emitting layer 5 Electron injection layer 6 Substrate 7 Metal dope molybdenum oxide layer

Claims (20)

An organic electroluminescence device having an anode, a cathode, and a light emitting layer interposed between the anode and the cathode,
Between the anode and the light emitting layer, a metal doped molybdenum oxide layer made of metal doped molybdenum oxide,
An organic electroluminescence device having a layer formed by a coating method using a layer forming coating solution in which an alkali metal salt is dissolved between the light emitting layer and the cathode.   The organic electroluminescence device according to claim 1, wherein the metal-doped molybdenum oxide layer has a visible light transmittance of 50% or more.   The organic electroluminescent device according to claim 1 or 2, wherein the dopant metal contained in the metal-doped molybdenum oxide is selected from the group consisting of a transition metal, a group 13 metal of the periodic table, and a mixture thereof.   The organic electroluminescent element according to claim 3, wherein the dopant metal is aluminum.   The organic electroluminescent element of any one of Claims 1-4 whose ratio of the dopant metal in the said metal dope molybdenum oxide is 0.1-20.0 mol%.   The organic electroluminescent element according to any one of claims 1 to 5, further comprising a layer containing a polymer compound in contact with the metal-doped molybdenum oxide layer. Forming an anode, a cathode, and a light emitting layer interposed between the anode and the cathode;
Forming a metal-doped molybdenum oxide layer formed by simultaneously depositing molybdenum oxide and a dopant metal between the anode and the light-emitting layer;
Forming a layer by a coating method using a layer-forming coating solution in which an alkali metal salt is dissolved between the light emitting layer and the cathode. A method for producing an organic electroluminescent element.   The manufacturing method of the organic electroluminescent element of Claim 7 which performs the process of forming the said metal dope molybdenum oxide layer by vacuum evaporation, sputtering, or ion plating.   9. The method of manufacturing an organic electroluminescence device according to claim 8, wherein the step of forming the metal-doped molybdenum oxide layer further includes a step of heating a layer in which molybdenum oxide and a dopant metal are simultaneously deposited.   The said alkali metal salt is at least 1 sort (s) selected from the group which consists of molybdic acid, tungstic acid, tantalum acid, niobic acid, vanadate acid, titanic acid, and zinc acid among Claim 7-9 The manufacturing method of the organic electroluminescent element of any one.   The alkali metal salt according to any one of claims 7 to 10, wherein the alkali metal salt is at least one salt selected from the group consisting of lithium, sodium, potassium, rubidium, and cesium. Manufacturing method of organic electroluminescent element.   The manufacturing method of the organic electroluminescent element of any one of Claims 7-11 whose said alkali metal salt is a cesium salt.   The manufacturing method of the organic electroluminescent element of any one of Claims 7-12 whose said alkali metal salt is a cesium molybdate.   The manufacturing method of the organic electroluminescent element of any one of Claims 7-13 in which the said layer formation coating liquid contains alcohol and / or water.   The manufacturing method of the organic electroluminescent element of any one of Claims 7-14 in which the said layer formation coating liquid contains surfactant.   The method for producing an organic electroluminescent element according to any one of claims 7 to 15, wherein a contact angle of the layer forming coating solution with respect to a substrate made of polyethylene naphthalate is 60 ° or less.   The method for producing an organic electroluminescent element according to any one of claims 7 to 16, wherein a hydrogen ion index of the layer forming coating solution is 7 or more and 13 or less.   An illuminating device provided with the organic electroluminescent element of any one of Claims 1-6.   A planar light source comprising the organic electroluminescence element according to any one of claims 1 to 6.   A display apparatus provided with the organic electroluminescent element of any one of Claims 1-6.

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