JP4854800B2 - Organic electroluminescence device - Google Patents

Description

  The present invention relates to an organic electroluminescence device that emits light by converting electric energy into light.

  Durability has been studied as an effort toward practical application of a light-emitting display device having an organic electroluminescent element. In particular, organic electroluminescence devices are subject to use under high-temperature environments such as automobiles, summer, and tropical areas that are prone to deterioration due to heat and easily rise in temperature, and improvement in thermal durability is desired. Yes.

  Among organic electroluminescent elements, blue light-emitting elements exhibiting a blue color have low heat durability, and it has been proposed to use a styrylamine compound having good heat durability as a blue light-emitting material (Patent Documents 1 to 3). 5). However, these proposals also have a problem that sufficient heat durability for practical use cannot be obtained.

As a technique for improving the durability, an organic electroluminescent element in which a host material layer made of a host material used for a light emitting layer is disposed adjacent to the light emitting layer has been proposed (see Patent Documents 6 and 7).
According to these proposals, the durability of the device can be improved to a certain extent, but it is not described that the heat resistance is improved, and it is applied to an organic electroluminescent device for the purpose of improving the heat resistance. There is a problem that it is difficult.

  In addition, by suppressing concentration quenching in the light emitting layer, a light emitting layer is formed with two or more doped portions containing a light emitting dopant and a non-doped portion not containing this for the purpose of obtaining a high-luminance device. It has been proposed (see Patent Document 8). However, there is no description about improvement in heat resistance, and there is a problem that it is difficult to apply to an organic electroluminescence device aiming at improvement in heat resistance.

JP 2007-227152 A JP 2003-272857 A JP 2006-273737 A JP 2005-203364 A International Publication No. 2005-117499 JP 2007-42875 A Japanese Patent Laid-Open No. 2004-311231 JP 2009-37981 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, an object of the present invention is to provide an organic electroluminescent device having high heat resistance and excellent durability against temperature change.

  In order to solve the above-mentioned problems, the present inventors have conducted intensive studies, and the following knowledge has been obtained. That is, a styrylamine compound is used as a light emitting material, and a light emitting layer including the compound is formed of a light emitting material doped layer and a light emitting material undoped layer, and further, from the same host material as the host material included in the light emitting layer. When the host material layer is arranged adjacent to the light emitting layer, due to these synergistic effects, the blue light emitting device, which has previously had insufficient heat durability, has durability against driving and temperature change in a high temperature environment. It has been found that the heat resistance can be remarkably improved and the remarkably excellent heat resistance can be obtained.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> A light emitting layer comprising a light emitting material comprising a styrylamine compound and a host material, a light emitting material doped layer, a light emitting material undoped layer comprising the host material, and adjacent to at least one surface of the light emitting layer. A host material layer made of the same host material as the host material contained in the light emitting layer, wherein the styrylamine compound is a blue light emitting material, and the light emitting material is doped. It is an organic electroluminescent element characterized by being contained in 1 to 20 mass% in a layer.
<2> Two or three light emitting material doped layers containing a light emitting material and a host material made of a styrylamine compound, and one and two made of the host material and disposed between the light emitting material doped layers A light-emitting layer having any one of the light-emitting material undoped layers, a host material layer made of the same host material as the host material included in the light-emitting layer, adjacent to at least one surface of the light-emitting layer, And the styrylamine compound is a blue light emitting material.
<3> From <1> to <2 above, wherein the light emitting layer has one light emitting material undoped layer between two light emitting material doped layers including the first light emitting material doped layer and the second light emitting material doped layer. > The organic electroluminescent element according to any one of the above.
<4> The light emitting layer includes three light emitting material doped layers including a first light emitting material doped layer, a second light emitting material doped layer, and a third light emitting material doped layer, a first light emitting material undoped layer, and A first light-emitting material between the first light-emitting material-doped layer and the second light-emitting material-doped layer. <1> to <2>, wherein an undoped layer is disposed, and the second light emitting material undoped layer is disposed between the second light emitting material doped layer and the third light emitting material doped layer. It is an organic electroluminescent element in any one.
<5> The organic electroluminescent element according to any one of <1> to <4>, wherein the host material layer is disposed adjacent to each of the one surface and the other surface of the light emitting layer. .
<6> The organic electroluminescence device according to any one of <1> to <5>, wherein the styrylamine compound is a compound represented by the following general formula (1).
However, in said general formula (1), Ar < ₁ >, Ar < ₂ >, Ar < ₃ >, Ar < ₅ > and Ar < ₆ > represent either a hydrogen atom or an aryl group, respectively, and the said aryl group is linear or branched. Ar ₄ may be substituted with at least one of an alkyl group, a substituted or unsubstituted aryl group and an amino group, and Ar ₄ represents a substituted or unsubstituted arylene group.
<7> The organic electroluminescence device according to any one of <1> to <6>, wherein the host material is at least one of an anthracene compound, a pyrene compound, and a chrysene compound.
<8> From the above <1>, the styrylamine compound and the host material contained in at least one of the light emitting material doped layers among the at least two light emitting material doped layers are any of the following (1) to (3): <7> The organic electroluminescence device according to any one of <7>.
(1) The styrylamine compound is a compound (Dopant-1) represented by the following structural formula, and the host material is a compound (Host-1) represented by the following structural formula.
(2) The styrylamine compound is a compound (Dopant-3) represented by the following structural formula, and the host material is a compound (Host-2) represented by the following structural formula.
(3) The styrylamine compound is a compound (Dopant-5) represented by the following structural formula, and the host material is a compound (Host-3) represented by the following structural formula.

  ADVANTAGE OF THE INVENTION According to this invention, the said various problems in the past can be solved, the said objective can be achieved, an organic electroluminescent element which has high heat resistance and is excellent in durability with respect to a temperature change can be provided.

FIG. 1 is a schematic cross-sectional view of the organic electroluminescent element according to the first embodiment. FIG. 2 is a schematic cross-sectional view of an organic electroluminescent element according to the second embodiment. FIG. 3 is a schematic cross-sectional view of an organic electroluminescent element according to the third embodiment. FIG. 4 is a schematic cross-sectional view of an organic electroluminescent element according to the fourth embodiment. FIG. 5 is a schematic cross-sectional view of an organic electroluminescent element according to the fifth embodiment. FIG. 6 is a schematic cross-sectional view of an organic electroluminescent element according to the sixth embodiment.

(Organic electroluminescence device)
The organic electroluminescent element of the present invention includes a light emitting layer and a host material layer, and includes other configurations as necessary.

<Light emitting layer>
The light emitting layer includes a light emitting material doped layer and a light emitting material undoped layer.
In such a configuration of the light emitting layer, when a voltage is applied between the anode and the cathode, charges are injected into the light emitting layer. Then, holes and electrons are recombined to generate excitation energy, and the excitation energy is transferred to the light emitting material to obtain light emission.
Charge recombination also occurs in each of the luminescent material doped layer and the luminescent material undoped layer. Excitons of the light emitting material doped layer as well as excitons of the light emitting material undoped layer transfer energy to the light emitting material of the light emitting material doped layer and contribute to light emission.

Although there is no restriction | limiting in particular as the whole thickness of the said light emitting layer, 10 nm-100 nm are preferable, 20 nm-60 nm are more preferable, and 30 nm-40 nm are especially preferable.
If the thickness is less than 10 nm, the light emission efficiency may decrease and the device may easily leak. If the thickness exceeds 100 nm, the light emission efficiency may decrease, the drive voltage may increase, and the chromaticity change due to driving may increase. is there.

-Light emitting material doped layer-
The light emitting material doped layer includes a light emitting material and a host material made of a styrylamine compound.
There is no restriction | limiting in particular as the number of layers of the said light emitting material dope layer, According to the objective, it can select suitably, For example, two layers or three layers may be sufficient.

Although there is no restriction | limiting in particular as content of the said luminescent material in one luminescent material dope layer, 1 mass%-30 mass% are preferable, 1 mass%-20 mass% are more preferable, 3 mass%-20 mass% Is more preferable, and 5% by mass to 10% by mass is particularly preferable.
If the content is less than 1% by mass, the light emission efficiency may be reduced, and if it exceeds 30% by mass, the drive durability may be reduced.
In addition, as said content rate in several light emitting material dope layer, although it may respectively be same or different, it is preferable that it is the same.

The specific thickness of the light emitting material doped layer is preferably 1 nm to 100 nm, more preferably 3 nm to 60 nm, and particularly preferably 5 nm to 30 nm.
If the thickness is less than 1 nm, the light emission efficiency and drive durability may be reduced, and if it exceeds 100 nm, the drive voltage may be increased.
In particular, each light emitting material dope in the case where the light emitting layer has one light emitting material undoped layer between two light emitting material doped layers composed of a first light emitting material doped layer and a second light emitting material doped layer. The thickness of the layer is preferably 5 nm to 15 nm from the above viewpoint. In this case, the thicknesses of the respective light emitting material dope layers may be different from each other, but it is preferable that they have the same thickness from the viewpoint of improving heat resistance.
The light emitting layer includes three light emitting material doped layers including a first light emitting material doped layer, a second light emitting material doped layer, and a third light emitting material doped layer, a first light emitting material undoped layer, and A first light-emitting material between the first light-emitting material-doped layer and the second light-emitting material-doped layer. Each of the light emitting material doped layers in the case where an undoped layer is disposed and the second light emitting material undoped layer is disposed between the second light emitting material doped layer and the third light emitting material doped layer The thickness is preferably 5 nm to 10 nm from the above viewpoint. In this case, the thicknesses of the respective light emitting material dope layers may be different from each other. However, from the viewpoint of improving heat resistance, it is preferable that each has a comparable thickness.

--Luminescent material--
The luminescent material is not particularly limited as long as it is a styrylamine compound. For example, styrylamine compounds such as styrylamine and amine-substituted styryl compounds are preferable. For example, a compound represented by the following general formula (1) is used. preferable. These styrylamine compounds exhibit blue fluorescence.

However, in the general formula (1), Ar ₁ to Ar ₃ , Ar ₅ and Ar ₆ each represent a hydrogen atom or an aryl group, and the aryl group is a linear or branched alkyl. Ar ₄ may be substituted with at least one of a group, a substituted or unsubstituted aryl group and an amino group, and Ar ₄ represents a substituted or unsubstituted arylene group.

Regarding the Ar ₁ to Ar ₃ , Ar ₅ and Ar ₆ , examples of the aryl group include a phenyl group, a naphthyl group, and an anthranyl group. Examples of the linear or branched alkyl group include a methyl group, an ethyl group, a propyl group, a butyl group, an iso-propyl group, and a tert-butyl group. The amino group may be further substituted with the aryl group.
Regarding Ar ₄ , examples of the substituted or unsubstituted arylene group include a substituted or unsubstituted phenylene group, naphthalene group, and anthracenylene group.
Below, an example of the preferable compound of a styrylamine compound is shown. In addition, the light emitting material of each layer used for the at least two light emitting material doped layers may be the same or different.

-Host material-
The host material is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include anthracene compounds, pyrene compounds, chrysene compounds, and these compounds having an asymmetric structure. Among these, anthracene compounds, particularly anthracene compounds having an asymmetric structure are preferable.
Specific examples of host materials that can be suitably used are shown below.

In the light-emitting layer, the styryl compound contained in at least one light-emitting material doped layer and the host material are preferably any of the following (1) to (3), and the styryl compound in all the light-emitting material doped layers More preferably, the host material is any one of the following (1) to (3).
That is, (1) The styrylamine compound is a compound (Dopant-1) represented by the following structural formula, and the host material is a compound (Host-1) represented by the following structural formula.
(2) The styrylamine compound is a compound (Dopant-3) represented by the following structural formula, and the host material is a compound (Host-2) represented by the following structural formula.
(3) The styrylamine compound is a compound (Dopant-5) represented by the following structural formula, and the host material is a compound (Host-3) represented by the following structural formula.

-Light-emitting material undoped layer-
The light emitting material undoped layer is made of the same host material as the host material in the light emitting material doped layer, and at least one light emitting material undoped layer is disposed between the two light emitting material doped layers.

Although there is no restriction | limiting in particular as thickness of the said light emitting material undoped layer, It is preferable that it is thicker than the thickness of the said light emitting material dope layer. In this case, even when the light emitting material concentration of the light emitting material doped layer is increased, the effect of diluting the light emitting material concentration of the entire light emitting layer is high, and concentration quenching can be effectively prevented.
The specific thickness of the light emitting material undoped layer is preferably 1 nm to 50 nm, more preferably 5 nm to 30 nm, and particularly preferably 10 nm to 20 nm.
If the thickness is less than 1 nm, a synergistic effect on driving durability and heat resistance may not be obtained, and if it exceeds 50 nm, a synergistic effect on driving durability and heat resistance may not be obtained.
In particular, the light emitting material undoped when the light emitting layer has one light emitting material undoped layer between two light emitting material doped layers comprising a first light emitting material doped layer and a second light emitting material doped layer. The thickness of the layer is preferably 15 nm to 20 nm from the above viewpoint.
The light emitting layer includes three light emitting material doped layers including a first light emitting material doped layer, a second light emitting material doped layer, and a third light emitting material doped layer, a first light emitting material undoped layer, and A first light-emitting material between the first light-emitting material-doped layer and the second light-emitting material-doped layer. Each of the light emitting material doped non-layers when an undoped layer is disposed and the second light emitting material undoped layer is disposed between the second light emitting material doped layer and the third light emitting material doped layer The thickness is preferably 5 nm to 15 nm from the above viewpoint. In this case, the thicknesses of the respective light-emitting material undoped layers may be different from each other, but preferably have the same thickness from the viewpoint of improving heat resistance.

<Host material layer>
The host material layer is adjacent to any surface of the light emitting layer and is composed of the same host material as the host material included in the light emitting layer.

  The host material is not limited as long as it is a host material contained in the adjacent light emitting layer, and examples thereof include a host material used for the blue light emitting layer.

The thickness of the host material layer is not particularly limited, but is preferably 1 nm to 15 nm, more preferably 3 nm to 12 nm, and particularly preferably 5 nm to 10 nm.
When the thickness is less than 1 nm, a synergistic effect on driving durability and heat resistance may not be obtained. When the thickness exceeds 15 nm, the driving voltage may increase or the light emission efficiency may decrease.

The host material layer is preferably disposed adjacent to one surface of the light emitting layer and the other surface.
When configured in this way, although not certain, one of the factors of driving element deterioration is the alteration of the material due to the reaction between the light-emitting material and the carrier transport material in the layer adjacent to the light-emitting layer. It is thought that it will come out bigger.
Therefore, it is considered that this reaction is promoted by the diffusion of the light emitting material into the adjacent layer during driving or the diffusion of the material of the adjacent layer into the light emitting layer, and the host material layer is provided on both sides of the light emitting layer. Therefore, mixing of each material between the hole transport layer and the light emitting layer and between the electron transport layer and the light emitting layer due to the diffusion of the material can be prevented. From the viewpoint of device durability and heat resistance, the host is provided on both sides of the light emitting layer. The above-described configuration in which a material layer is provided is preferable.

<Other configurations>
A configuration of an organic electroluminescent element including the light emitting layer and the host material layer will be described.
The organic electroluminescence device has an organic compound layer including at least the light emitting layer between a pair of electrodes (anode and cathode), and further includes a hole transport layer between the anode and the light emitting layer, and a cathode. An electron transport layer is provided between the light-emitting layer.
As a structure of the said organic compound layer, the aspect laminated | stacked in order of the said positive hole transport layer, the said light emitting layer, and the said electron carrying layer from the said anode side is mentioned.
Moreover, what provided the said positive hole injection layer between the said anode and the said positive hole transport layer, and similarly provided the electron injection layer between the said cathode and the said electron transport layer is mentioned.
The organic electroluminescent element can be configured as follows.
(1) Anode / host material layer / light emitting layer / cathode (2) Anode / light emitting layer / host material layer / cathode (3) Anode / host material layer / light emitting layer / host material layer / cathode (4) Anode / hole Transport layer / host material layer / light emitting layer / cathode (5) anode / hole transport layer / light emitting layer / host material layer / cathode (6) anode / hole transport layer / host material layer / light emitting layer / host material layer / Cathode (7) Anode / Host Material Layer / Light Emitting Layer / Electron Transport Layer / Cathode (8) Anode / Light Emitting Layer / Host Material Layer / Electron Transport Layer / Cathode (9) Anode / Host Material Layer / Light Emitting Layer / Host Material Layer / Electron transport layer / cathode (10) anode / hole injection layer / hole transport layer / host material layer / light emitting layer / electron transport layer / cathode (11) anode / hole injection layer / hole transport layer / light emitting layer / Host material layer / electron transport layer / cathode (12) anode / hole injection layer / hole transport layer / host material layer / light emitting layer Host material layer / electron transport layer / cathode (13) anode / hole transport layer / host material layer / light emitting layer / electron transport layer / electron injection layer / cathode (14) anode / hole transport layer / light emitting layer / host material Layer / electron transport layer / electron injection layer / cathode (15) anode / hole transport layer / host material layer / light emitting layer / host material layer / electron transport layer / electron injection layer / cathode (16) anode / hole injection layer / Hole transport layer / host material layer / light emitting layer / electron transport layer / electron injection layer / cathode (17) anode / hole injection layer / hole transport layer / light emitting layer / host material layer / electron transport layer / electron injection Layer / cathode (18) anode / hole injection layer / hole transport layer / host material layer / light emitting layer / host material layer / electron transport layer / electron injection layer / cathode

In the organic electroluminescent element of the present invention, the light emitting layer further includes at least two light emitting material doped layers and at least one light emitting material undoped layer disposed between the light emitting material doped layers in the above configuration. Is one of the features.
Hereinafter, the aspect is demonstrated using drawing.
FIG. 1 is a schematic cross-sectional view showing the layer configuration of the organic electroluminescent device 100 according to the first embodiment. The organic electroluminescent element 100 includes a hole injection layer 2, a hole transport layer 3, a host material layer 4, a first light emitting material doped layer 5a, a light emitting material undoped layer 6, and a second light emitting material from the anode 1 side. The doped layer 5b, the electron transport layer 7, the electron injection layer 8, and the cathode 9 are formed in this order.
FIG. 2 is a schematic cross-sectional view showing the layer configuration of the organic electroluminescent element 200 according to the second embodiment. The organic electroluminescent device 200 includes a hole injection layer 2, a hole transport layer 3, a first light emitting material doped layer 5a, a light emitting material undoped layer 6, a second light emitting material doped layer 5b, and a host from the anode 1 side. The material layer 4, the electron transport layer 7, the electron injection layer 8, and the cathode 9 are configured in this order.
FIG. 3 is a schematic cross-sectional view showing the layer configuration of the organic electroluminescent element 300 according to the third embodiment. The organic electroluminescent element 300 includes a hole injection layer 2, a hole transport layer 3, a first host material layer 4a, a first light emitting material doped layer 5a, a light emitting material undoped layer 6, and a second layer from the anode 1 side. The light emitting material doped layer 5b, the second host material layer 4b, the electron transport layer 7, the electron injection layer 8, and the cathode 9 are formed in this order.
FIG. 4 is a schematic cross-sectional view showing the layer configuration of the organic electroluminescent element 400 according to the fourth embodiment. The organic electroluminescent element 400 includes a positive hole injection layer 2, a positive hole transport layer 3, a host material layer 4, a first light emitting material doped layer 5a, a first light emitting material undoped layer 6a, and a second layer from the anode 1 side. The light emitting material doped layer 5b, the second light emitting material undoped layer 6b, the third light emitting material doped layer 5c, the electron transport layer 7, the electron injection layer 8, and the cathode 9 are formed in this order.
FIG. 5 is a schematic cross-sectional view showing the layer configuration of the organic electroluminescent element 500 according to the fifth embodiment. The organic electroluminescent element 500 includes a hole injection layer 2, a hole transport layer 3, a first light emitting material doped layer 5a, a first light emitting material undoped layer 6a, and a second light emitting material doped layer from the anode 1 side. 5b, the second light emitting material undoped layer 6b, the third light emitting material doped layer 5c, the host material layer 4, the electron transport layer 7, the electron injection layer 8, and the cathode 9.
FIG. 6 is a schematic cross-sectional view showing a layer configuration of an organic electroluminescent element 600 according to the sixth embodiment. The organic electroluminescent device 600 includes a hole injection layer 2, a hole transport layer 3, a first host material layer 4a, a first light emitting material doped layer 5a, and a first light emitting material undoped layer 6a from the anode 1 side. , Second luminescent material doped layer 5b, second luminescent material undoped layer 6b, third luminescent material doped layer 5c, second host material layer 4b, electron transport layer 7, electron injection layer 8, and cathode 9 It is composed in order.
In these drawings, reference numerals 10 and 10 ′ denote light emitting layers.

As each organic layer such as the light emitting layer, the host material layer, the hole transport layer, the hole injection layer, the electron transport layer, and the electron injection layer, a vapor deposition method, a sputtering method, a transfer method, a printing method, a coating method, an ink jet method, etc. It can be suitably formed by any method such as spraying.
Hereinafter, configurations other than the light emitting layer and the host material layer described above will be described.

-Anode-
The anode may have a function as an electrode for supplying holes to the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. Thus, it can be appropriately selected from known electrode materials.

  Suitable examples of the material for the anode include metals, alloys, metal oxides, conductive compounds, and mixtures thereof, and materials having a work function of 4.0 eV or more are preferable. Specific examples of the anode material include conductive metals such as tin oxide doped with antimony and fluorine (ATO, FTO), tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), and indium zinc oxide (IZO). Metals such as oxides, gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, polyaniline, polythiophene, polypyrrole, etc. Organic conductive materials, and a laminate of these and ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  Examples of the method for forming the anode include a printing method, a wet method such as a coating method, a physical method such as a vacuum deposition method, a sputtering method, and an ion plating method, and a chemical method such as CVD and plasma CVD method. Thus, it can be formed according to a method appropriately selected in consideration of suitability with the material constituting the anode. For example, when ITO is selected as the anode material, the anode can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like.

  As a patterning method for forming the anode, chemical etching by photolithography or the like may be used, physical etching by laser or the like may be used, and vacuum deposition or sputtering may be performed by overlaying a mask. Etc., or by a lift-off method or a printing method.

The thickness of the anode is preferably 10 nm to 50 μm, and more preferably 50 nm to 20 μm.
The resistance value of the anode is preferably 10 ³ Ω / □ or less, and more preferably 10 ² Ω / □ or less. When the anode is transparent, it may be colorless and transparent or colored and transparent. In order to take out light emission from the transparent anode side, the transmittance is preferably 60% or more, and more preferably 70% or more.

  The transparent anode is described in detail in the book “New Development of Transparent Electrode Films” published by CMC (1999), supervised by Yutaka Sawada, and the matters described here can be applied to the present invention. In the case of using a plastic substrate having low heat resistance, a transparent anode formed using ITO or IZO at a low temperature of 150 ° C. or lower is preferable.

-Cathode-
The cathode usually has a function as an electrode for injecting electrons into the organic compound layer, and there is no particular limitation on the shape, structure, size, etc., depending on the use and purpose of the light-emitting element. Thus, it can be appropriately selected from known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof, and those having a work function of 4.5 eV or less are preferable. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium, ytterbium, and the like. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection.

Among these, as a material constituting the cathode, an alkali metal or an alkaline earth metal is preferable from the viewpoint of electron injecting property, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability.
The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  There is no restriction | limiting in particular as a formation method of the said cathode, According to a well-known method, it can carry out. For example, the cathode described above is configured from a wet method such as a printing method or a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. It can be formed according to a method appropriately selected in consideration of suitability with the material. For example, when a metal or the like is selected as the cathode material, one or more of them can be simultaneously or sequentially performed according to a sputtering method or the like.

  As a patterning method for forming the cathode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using laser or the like, and is performed by vacuum deposition or sputtering with a mask overlapped. Alternatively, it may be performed by a lift-off method or a printing method.

The thickness of the cathode is preferably 10 nm to 5 μm, and more preferably 50 nm to 1 μm.
Further, the cathode may be transparent or opaque. The transparent cathode can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

-Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side.
The material for forming the hole injection layer and the hole transport layer is not particularly limited, and examples thereof include pyrrole derivatives, carbazole derivatives, pyrazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, and polyarylalkanes. Derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, thiophene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine Compounds, aromatic dimethylidin compounds, porphyrin compounds, phthalocyanine compounds, organosilane derivatives, and carbon are preferable.

  Among them, a pyrrole derivative, a carbazole derivative, a phenylenediamine derivative, an arylamine derivative, a thiophene derivative, and a phthalocyanine compound are preferable, and a carbazole derivative, an arylamine derivative, a thiophene derivative, and a phthalocyanine compound are more preferable. Derivatives, thiophene derivatives, and phthalocyanine compounds are particularly preferable, and carbazole derivatives and arylamine derivatives are particularly preferable as the hole transport layer material.

The thicknesses of the hole injection layer and the hole transport layer are not particularly limited, but are preferably 1 nm to 5 μm and more preferably 5 nm to 1 μm from the viewpoints of lowering driving voltage, improving luminous efficiency, and improving durability. 10 nm to 500 nm is particularly preferable.
Note that the driving voltage of the hole injection layer and the hole transport layer can be reduced by chemical doping or the like.
The hole injection layer and the hole transport layer may have a single layer structure composed of one or more of the forming materials, or a multilayer structure composed of a plurality of layers having the same composition or different compositions. May be.

-Electron injection layer, electron transport layer-
The electron injection layer and the electron transport layer are layers having any one of a function of injecting electrons from the cathode, a function of transporting electrons, and a function of blocking holes injected from the anode.
The material for forming the electron injection layer and the electron transport layer is not particularly limited, and examples thereof include pyridine, pyrimidine, triazine, imidazole, triazole, oxazole, oxadiazol, thiazole, thiadiazole, fluorenone, and anthraquino. Heterocyclic tetracarboxylic anhydrides such as dimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, naphthaleneperylene, phthalocyanine, silole and their derivatives ( Other rings may form condensed rings), various metal complexes represented by metal complexes of 8-quinolinol derivatives, metal phthalocyanines, benzoxazoles and benzothiazoles as ligands, etc. Can be mentioned.

  Among them, pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, imidazole derivatives, triazole derivatives, oxazole derivatives, oxadiazol derivatives, thiazole derivatives, thiadiazole derivatives, fluorine-substituted aromatic compounds, silole derivatives, 8-quinolinol derivatives Metal complexes (which may form condensed rings with other rings) are preferred, and metal complexes of pyridine derivatives, pyrimidine derivatives, pyrazine derivatives, triazine derivatives, imidazole derivatives, triazole derivatives, silole derivatives, 8-quinolinol derivatives (They may form a condensed ring with other rings.), And pyridine derivatives, pyrazine derivatives, triazine derivatives, imidazole derivatives, triazole derivatives, silole derivatives, 8-quinolinol. Conductor of the metal complex (which may form a condensed ring with another ring.) Is particularly preferred.

The thicknesses of the electron injection layer and the electron transport layer are not particularly limited, but are preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, more preferably 10 nm from the viewpoints of lowering driving voltage, improving luminous efficiency, and improving durability. ˜500 nm is particularly preferred.
Note that the driving voltage of the electron injection layer and the electron transport layer can be reduced by chemical doping or the like.
The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the forming materials, or a multilayer structure composed of a plurality of layers having the same composition or different compositions. Good.

-Board-
Although there is no restriction | limiting in particular as said board | substrate, It is preferable that it is a board | substrate which does not scatter or attenuate the light emitted from an organic compound layer. Specific examples include zirconia-stabilized yttrium (YSZ), inorganic materials such as glass, polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, and polycycloolefin. , Organic materials such as norbornene resin and poly (chlorotrifluoroethylene).
For example, when glass is used as the substrate, alkali-free glass is preferably used as the material in order to reduce ions eluted from the glass. Moreover, when using soda-lime glass, it is preferable to use what gave barrier coatings, such as a silica. In the case of an organic material, it is preferable that it is excellent in heat resistance, dimensional stability, solvent resistance, electrical insulation, and workability.

  There is no restriction | limiting in particular about the shape of the said board | substrate, a structure, a magnitude | size, It can select suitably according to the use, purpose, etc. of a light emitting element. In general, the shape of the substrate is preferably a plate shape. The structure of the substrate may be a single layer structure, a laminated structure, may be formed of a single member, or may be formed of two or more members.

  The substrate may be colorless and transparent or colored and transparent, but is preferably colorless and transparent in that it does not scatter or attenuate light emitted from the organic light emitting layer.

The substrate may be provided with a moisture permeation preventing layer (gas barrier layer) on the front surface or the back surface.
As a material for the moisture permeation preventive layer (gas barrier layer), inorganic materials such as silicon nitride and silicon oxide are preferably used. The moisture permeation preventing layer (gas barrier layer) can be formed by, for example, a high frequency sputtering method.
When a thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

-Protective layer-
The entire organic electroluminescent element may be protected by a protective layer.
As a material contained in the protective layer, any material may be used as long as it has a function of preventing a material that promotes device deterioration such as moisture or oxygen from entering the device.
Specific examples thereof include metals such as In, Sn, Pb, Au, Cu, Ag, Al, Ti, and Ni, MgO, SiO, SiO ₂ , Al ₂ O ₃ , GeO, NiO, CaO, BaO, and Fe ₂ O. ₃ , metal oxides such as Y ₂ O ₃ and TiO ₂ , metal nitrides such as SiN _x and SiN _x O _y , metal fluorides such as MgF ₂ , LiF, AlF ₃ and CaF ₂ , polyethylene, polypropylene, polymethyl Monomer mixture containing methacrylate, polyimide, polyurea, polytetrafluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, copolymer of chlorotrifluoroethylene and dichlorodifluoroethylene, tetrafluoroethylene and at least one comonomer A copolymer obtained by copolymerization of a copolymer having a cyclic structure in the copolymer main chain. Copolymer, 1% by weight of the water absorbing water absorption material, water absorption of 0.1% or less of moisture-proof material, and the like.

  The method for forming the protective layer is not particularly limited. For example, the vacuum deposition method, the sputtering method, the reactive sputtering method, the MBE (molecular beam epitaxy) method, the cluster ion beam method, the ion plating method, the plasma polymerization method ( High frequency excitation ion plating method), plasma CVD method, laser CVD method, thermal CVD method, gas source CVD method, coating method, printing method, transfer method can be applied.

-Sealing-
Furthermore, the organic electroluminescent element may be sealed entirely using a sealing container.
Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. The moisture absorbent is not particularly limited, and examples thereof include barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, and chloride. Examples thereof include copper, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide.
The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorine-based solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorine-based solvents, and silicone oils. Can be mentioned.

  The organic electroluminescence device obtains light emission by applying a direct current (which may include an alternating current component as necessary) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Can do.

  Examples of the driving method of the organic electroluminescence device of the present invention include, for example, JP-A-2-148687, JP-A-6-301355, JP-A-5-29080, JP-A-7-134558, JP-A-8-234585, and JP-A-8-241047. No. 2,784,615, U.S. Pat. Nos. 5,828,429, 6023308, and the like, and the like can be applied.

  The organic electroluminescent element can be used for, for example, a light-emitting display device, a display, a backlight, electrophotography, an illumination light source, a recording light source, an exposure light source, a reading light source, a sign, a signboard, interior, optical communication, etc. It can be suitably used for an interior display of an automobile exposed underneath.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
On a glass substrate having a thickness of 0.5 mm and a square of 2.5 cm, ITO (Indium Tin Oxide) was provided as an anode by a sputtering method so as to have a thickness of 70 nm. Next, this ITO-attached glass substrate was put into a cleaning container, subjected to ultrasonic cleaning in 2-propanol, and then subjected to UV-ozone treatment for 30 minutes.
Next, on the glass substrate with ITO, a hole transport material (HTM-1) represented by the following structural formula is deposited so as to have a thickness of 60 nm, and a first hole transport layer (HTL) is formed. Formed.

Next, a hole transport material (HTM-2) represented by the following structural formula is deposited on the first hole injection layer so as to have a thickness of 15 nm, and the second hole transport layer ( HTL) was formed.

Next, a host material (Host-1) represented by the following structural formula was deposited on the second hole transport layer so as to have a thickness of 5 nm, thereby forming a first host material layer.

Next, a light-emitting layer using the host material (Host-1) and a compound represented by the following structural formula (Dopant-1) as a light-emitting material was formed over the host material layer.
Specifically, the compound (Dopant-1) serving as the light emitting material and the compound (Host-1) serving as the host were installed in different vapor deposition sources of the vapor deposition apparatus. Then, both the boats were heated, and the opening and closing of the shutter on the side where the compound (Dopant-1) was installed was appropriately switched to laminate two light emitting material doped layers and one light emitting material undoped layer. That is, the first light emitting material doped layer, the light emitting material undoped layer, and the second light emitting material doped layer were laminated in this order from the anode side.
At this time, the thicknesses of the two light emitting material doped layers were adjusted to 10 nm and the thickness of the one light emitting material undoped layer was adjusted to 20 nm by setting the time for opening and closing the shutter, respectively. The total thickness of the light emitting layer was 40 nm. Moreover, the density | concentration of the compound (Dopant-1) used as the light emitting material in a light emitting material dope layer was 10 mass%.

  Next, a host material (Host-1) was deposited on the light emitting layer in the same manner as the first host material layer so as to have a thickness of 5 nm to form a second host material layer.

Next, tris (8-quinolinolato) aluminum (Alq ₃ ) represented by the following structural formula was deposited on the second host material layer so as to have a thickness of 15 nm to form an electron transport layer.

Next, LiF was deposited on the electron transport layer so as to have a thickness of 1 nm to form an electron injection layer.
Aluminum (Al) was deposited on the electron injection layer so as to have a thickness of 100 nm to form a cathode.
The laminate produced as described above is placed in a glove box substituted with argon gas, and a stainless steel sealing can, a desiccant (HD-S-071205-40, manufactured by Dynic Co., Ltd.), and an ultraviolet curable adhesive ( XNR5516HV, manufactured by Nagase Ciba Co., Ltd.) was used to manufacture the organic electroluminescent element in Example 1.

(Example 2)
In Example 1, the second host material layer was not formed on the light emitting layer, an electron transport layer was formed, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. Then, an organic electroluminescent device in Example 2 was produced.

(Comparative Example A)
In Example 1, Comparative Example A was carried out in the same manner as Example 1 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 0.5% by mass. An organic electroluminescent device was manufactured.

(Example A)
In Example 1, the organic material in Example A was changed in the same manner as in Example 1 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 5% by mass. An electroluminescent device was manufactured.

(Example B)
In Example 1, the organic material in Example B was changed in the same manner as in Example 1 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 18% by mass. An electroluminescent device was manufactured.

(Comparative Example B)
In Example 1, the organic compound in Comparative Example B was used in the same manner as in Example 1, except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 20% by mass. An electroluminescent device was manufactured.

(Comparative Example C)
In Example 2, Comparative Example C was performed in the same manner as in Example 2 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 0.5% by mass. An organic electroluminescent device was manufactured.

(Example C)
In Example 2, the organic material in Example C was changed in the same manner as in Example 2 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 5% by mass. An electroluminescent device was manufactured.

(Example D)
In Example 2, the organic material in Example D was changed in the same manner as in Example 2 except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 18% by mass. An electroluminescent device was manufactured.

(Comparative Example D)
In Example 2, the organic compound in Comparative Example D was used in the same manner as in Example 2, except that the concentration of the compound (Dopant-1) serving as the light emitting material in the light emitting material doped layer was changed from 10% by mass to 20% by mass. An electroluminescent device was manufactured.

(Example 3)
In Example 1, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Example 3 was produced in the same manner as in Example 1 except that the thickness was changed from 15 nm to 20 nm.

(Comparative Example 1)
In Example 1, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the second host is formed on the light emitting layer. Except for forming the electron transport layer on the light emitting layer without forming the material layer, changing the thickness of the second hole transport layer from 15 nm to 20 nm, and changing the thickness of the electron transport layer from 15 nm to 20 nm, In the same manner as in Example 1, the organic electroluminescent element in Comparative Example 1 was produced.

(Comparative Example 2)
In Example 1, a comparison was made in the same manner as in Example 1 except that the light emitting layer was formed as follows instead of the light emitting layer in which two light emitting material doped layers and one light emitting material undoped layer were laminated. The organic electroluminescent element in Example 2 was manufactured.
That is, the host material (Host-1) and the light emitting material (Dopant-1) are vapor-deposited on the first host material layer so that the concentration of the light emitting material is 10% by mass and the thickness is 40 nm. A light emitting layer was formed.

(Comparative Example 3)
In Comparative Example 2, the second host material layer was not formed on the light emitting layer, the electron transport layer was formed on the light emitting layer, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. In the same manner as described above, an organic electroluminescent element in Comparative Example 3 was produced.

(Comparative Example 4)
In Comparative Example 2, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Comparative Example 4 was produced in the same manner as Comparative Example 2 except that the thickness was changed from 15 nm to 20 nm.

(Comparative Example 5)
In Example 1, the same procedure as in Example 1 was performed except that the compound (Dopant-2) represented by the following structural formula was used instead of the compound (Dopant-1) as the light emitting material. An organic electroluminescent device was manufactured.

(Comparative Example 6)
In Example 2, the organic electroluminescent element in Comparative Example 6 was produced in the same manner as in Example 2 except that the compound (Dopant-2) was used instead of the compound (Dopant-1) as the luminescent material. .

(Comparative Example 7)
In Example 3, the organic electroluminescent element in Comparative Example 7 was produced in the same manner as in Example 3 except that the compound (Dopant-2) was used instead of the compound (Dopant-1) as the luminescent material. .

(Comparative Example 8)
In Comparative Example 2, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Comparative Example 8 was produced in the same manner as Comparative Example 2 except that the thickness was changed from 15 nm to 20 nm.

The main structures of the organic electroluminescent elements in Examples 1 to 3 and Comparative Examples 1 to 8 are summarized in Table 1 below, and the main structures of the organic electroluminescent elements in Examples A to D and Comparative Examples A to D are shown. These structures are summarized in Table 1-2. In addition, the numerical value in () in a table | surface shows thickness (nm).

Example 4
In Example 1, in place of the light-emitting layer in which two light-emitting material doped layers and one light-emitting material undoped layer were stacked, the same procedure as in Example 1 was performed except that a light-emitting layer was formed as follows. The organic electroluminescent element in Example 4 was manufactured.
That is, the compound (Dopant-1) serving as the light emitting material and the compound (Host-1) serving as the host were installed in different vapor deposition sources of the vapor deposition apparatus. Then, both the boats are heated, and the shutter on the side where the compound (Dopant-1) is installed is appropriately switched to stack two light emitting material doped layers and one light emitting material undoped layer, and from the anode side, A first light emitting material doped layer, a first light emitting material undoped layer, a second light emitting material doped layer, a second light emitting material undoped layer, and a third light emitting material doped layer are stacked in this order. did.
At this time, depending on the time settings for opening and closing the shutter, the thicknesses of the first and third light emitting material doped layers are 7 nm, the second light emitting material doped layer is 6 nm, and the two light emitting material undoped layers are thick. Was adjusted to 10 nm. The total thickness of the light emitting layer was 40 nm. Moreover, the density | concentration of the compound (Dopant-1) used as the light emitting material in a light emitting material dope layer was 10 mass%.

(Example 5)
In Example 4, a host material layer was not formed on the light emitting layer, an electron transport layer was formed on the light emitting layer, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. Thus, an organic electroluminescent element in Example 5 was produced.

(Example 6)
In Example 4, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Example 6 was produced in the same manner as in Example 4 except that the thickness was changed from 15 nm to 20 nm.

(Comparative Example 9)
In Example 4, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the second host is formed on the light emitting layer. Except for forming the electron transport layer on the light emitting layer without forming the material layer, changing the thickness of the second hole transport layer from 15 nm to 20 nm, and changing the thickness of the electron transport layer from 15 nm to 20 nm, In the same manner as in Example 4, the organic electroluminescent element in Comparative Example 9 was produced.

(Comparative Example 10)
In Example 4, the organic electroluminescent element in Comparative Example 10 was produced in the same manner as in Example 4 except that the compound (Dopant-2) was used instead of the compound (Dopant-1) as the luminescent material. .

(Comparative Example 11)
In Example 5, the organic electroluminescent element in Comparative Example 11 was produced in the same manner as in Example 5 except that the compound (Dopant-2) was used instead of the compound (Dopant-1) as the luminescent material. .

(Comparative Example 12)
In Example 6, the organic electroluminescent element in Comparative Example 12 was produced in the same manner as in Example 6 except that the compound (Dopant-2) was used instead of the compound (Dopant-1) as the luminescent material. .

The main structures of the organic electroluminescent elements in Examples 4 to 6 and Comparative Examples 9 to 12 are summarized in Table 2 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Examples 7 to 9)
In Examples 1 to 3, the compound (Dopant-3) represented by the following structural formula was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-1) was used as the host material. Each organic electroluminescent element in Examples 7-9 was manufactured in the same manner as in Examples 1-3 except that the compound represented by the structural formula (Host-2) was used (see Table 3 below). ).

(Comparative Examples 13-16, 20)
In Comparative Examples 1-4 and 8, the compound (Dopant-3) was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-2) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Comparative Examples 13 to 16 and 20 was produced in the same manner as Comparative Examples 1 to 4 and 8 except that was used (see Table 3 below).

(Comparative Examples 17-19)
In Comparative Examples 5 to 7, a compound (Dopant-4) represented by the following structural formula was used instead of the compound (Dopant-2) as the light emitting material, and a compound instead of the compound (Host-1) was used as the host material. Except having used (Host-2), it carried out similarly to Comparative Examples 5-7, and manufactured each organic electroluminescent element in Comparative Examples 17-19 (refer Table 3 below).

The main structures of the organic electroluminescent elements in Examples 7 to 9 and Comparative Examples 13 to 20 are summarized in Table 3 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Examples 10 to 12)
In Examples 4 to 6, the compound (Dopant-3) was used instead of the compound (Dopant-1) as the luminescent material, and the compound (Host-2) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Examples 10 to 12 was produced in the same manner as in Examples 4 to 6 except for the above (see Table 4 below).

(Comparative Example 21)
In Comparative Example 9, the compound (Dopant-3) was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-2) was used as the host material instead of the compound (Host-1). The organic electroluminescent element in Comparative Example 21 was produced in the same manner as in Comparative Example 9 except for the above.

(Comparative Examples 22-24)
In Comparative Examples 10 to 12, the compound (Dopant-4) was used instead of the compound (Dopant-2) as the light emitting material, and the compound (Host-2) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Comparative Examples 22 to 24 was produced in the same manner as in Comparative Examples 10 to 12 (see Table 4 below).

The main structures of the organic electroluminescent elements in Examples 10 to 12 and Comparative Examples 21 to 24 are summarized in Table 4 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Examples 13 to 15)
In Examples 1 to 3, the compound (Dopant-5) represented by the following structural formula was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-1) was used as the host material. Each organic electroluminescent element in Examples 13 to 15 was produced in the same manner as in Examples 1 to 3 except that the compound represented by the structural formula (Host-3) was used (see Table 5 below). ).

(Comparative Examples 25-28, 32)
In Comparative Examples 1-4 and 8, the compound (Dopant-5) was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-3) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Comparative Examples 25 to 28 and 32 was produced in the same manner as Comparative Examples 1 to 4 and 8 except that was used (see Table 5 below).

(Comparative Examples 29-31)
In Comparative Examples 5 to 7, a compound (Dopant-6) represented by the following structural formula was used instead of the compound (Dopant-2) as the light emitting material, and a compound instead of the compound (Host-1) was used as the host material. Except having used (Host-2), it carried out similarly to Comparative Examples 5-7, and manufactured each organic electroluminescent element in Comparative Examples 29-31 (refer Table 5 below).

The main structures of the organic electroluminescent elements in Examples 13 to 15 and Comparative Examples 25 to 32 are summarized in Table 5 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Examples 16 to 18)
In Examples 4 to 6, the compound (Dopant-5) was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-3) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Examples 16 to 18 was produced in the same manner as in Examples 4 to 6 (see Table 6 below).

(Comparative Example 33)
In Comparative Example 9, the compound (Dopant-5) was used instead of the compound (Dopant-1) as the light emitting material, and the compound (Host-3) was used as the host material instead of the compound (Host-1). The organic electroluminescent element in Comparative Example 33 was produced in the same manner as in Comparative Example 9 except for the above.

(Comparative Examples 34 to 36)
In Comparative Examples 10 to 12, the compound (Dopant-6) was used instead of the compound (Dopant-2) as the light emitting material, and the compound (Host-3) was used as the host material instead of the compound (Host-1). Each organic electroluminescent element in Comparative Examples 34 to 36 was produced in the same manner as Comparative Examples 10 to 12 (see Table 6 below).

The main structures of the organic electroluminescent elements in Examples 16 to 18 and Comparative Examples 33 to 36 are summarized in Table 6 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Example 19)
In Example 1, the organic electroluminescent element in Example 19 was produced in the same manner as in Example 1 except that two light emitting material doped layers and one light emitting material undoped layer were formed as follows. .
That is, the compound (Dopant-1) and compound (Dopant-3) used as a luminescent material, and the compound (Host-1) used as a host were installed in different vapor deposition sources of the vapor deposition apparatus. Then, each boat is heated, and the opening and closing of the shutter on the side where the compound (Dopant-1) or the compound (Dopant-3) is installed is appropriately switched to stack two light emitting material doped layers and one light emitting material undoped layer. did. That is, from the anode side, a first light emitting material doped layer containing a compound (Dopant-1), a light emitting material undoped layer, and a second light emitting material doped layer containing a compound (Dopant-3) are stacked in this order. did.
At this time, the thicknesses of the two light emitting material doped layers were adjusted to 10 nm and the thickness of the one light emitting material undoped layer was adjusted to 20 nm by setting the time for opening and closing the shutter, respectively. The total thickness of the light emitting layer was 40 nm. Moreover, the density | concentration of the compound (Dopant-1) and compound (Dopant-3) used as the luminescent material in each luminescent material dope layer was 10 mass%, respectively.

(Example 20)
In Example 19, the second host material layer was not formed on the light emitting layer, the electron transport layer was formed on the light emitting layer, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. In the same manner as described above, an organic electroluminescent element in Example 20 was produced.

(Example 21)
In Example 19, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Example 21 was produced in the same manner as in Example 19 except that the thickness was changed from 15 nm to 20 nm.

(Example 22)
In Example 4, the organic electroluminescent element in Example 22 was produced in the same manner as in Example 4 except that three light emitting material doped layers and two light emitting material undoped layers were formed as follows. .
That is, the compound (Dopant-1), the compound (Dopant-3), and the compound (Dopant-5) as the light emitting material and the compound (Host-1) as the host were installed in different vapor deposition sources of the vapor deposition apparatus. Each boat is heated, and the shutter on the side where the compound (Dopant-1), the compound (Dopant-3) or the compound (Dopant-5) is installed is appropriately switched to open and close the three light emitting material doped layers and the two A light emitting material undoped layer was laminated. That is, from the anode side, a first light emitting material doped layer containing a compound (Dopant-1), a first light emitting material undoped layer, a second light emitting material doped layer containing a compound (Dopant-3), A second light emitting material undoped layer and a third light emitting material doped layer containing the compound (Dopant-5) were stacked in this order.
At this time, depending on the time settings for opening and closing the shutter, the thicknesses of the first and third light emitting material doped layers are 7 nm, the second light emitting material doped layer is 6 nm, and the two light emitting material undoped layers are thick. Were adjusted to 10 nm respectively. The total thickness of the light emitting layer was 40 nm. Moreover, the density | concentration of the compound (Dopant-1), the compound (Dopant-3), and the compound (Dopant-5) used as a luminescent material in each luminescent material dope layer was 10 mass%, respectively.

(Example 23)
In Example 22, the second host material layer was not formed on the light emitting layer, the electron transport layer was formed on the light emitting layer, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. In the same manner as described above, an organic electroluminescent element in Example 23 was produced.

(Example 24)
In Example 22, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the thickness of the second hole transport layer is increased. The organic electroluminescent element in Example 24 was produced in the same manner as in Example 22 except that the thickness was changed from 15 nm to 20 nm.

(Comparative Example 37)
In Example 19, the first host material layer was not formed on the second hole transport layer, the light emitting layer was formed on the second hole transport layer, and the second host material layer was formed on the light emitting layer. Example 2 except that the electron transport layer was formed on the light emitting layer without changing the thickness, the thickness of the second hole transport layer was changed from 15 nm to 20 nm, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. In the same manner as in Example 19, an organic electroluminescent element of Comparative Example 37 was produced.

(Comparative Examples 38-40)
In Examples 19 to 21, as the light emitting layer, the first light emitting material doped layer was formed using the compound (Dopant-2) instead of the compound (Dopant-1), and the compound instead of the compound (Dopant-3). Except having formed the 2nd light emitting material dope layer using (Dopant-4), it carried out similarly to Examples 19-21, and manufactured each organic electroluminescent element in Comparative Examples 38-40 (following). (See Table 7).

(Comparative Example 41)
In Example 22, the first host material layer is not formed on the second hole transport layer, the light emitting layer is formed on the second hole transport layer, and the second host material layer is formed on the light emitting layer. Example 2 except that the electron transport layer was formed on the light emitting layer without changing the thickness, the thickness of the second hole transport layer was changed from 15 nm to 20 nm, and the thickness of the electron transport layer was changed from 15 nm to 20 nm. In the same manner as in Example 22, an organic electroluminescent element of Comparative Example 41 was produced.

(Comparative Examples 42-44)
In Examples 22 to 24, as the light-emitting layer, the first light-emitting material doped layer was formed using the compound (Dopant-2) instead of the compound (Dopant-1), and the compound instead of the compound (Dopant-3). The second light emitting material dope layer was formed using (Dopant-4), and the same procedure as in Examples 22 to 24 was performed except that the compound (Dopant-6) was used instead of the compound (Dopant-5). The organic electroluminescent elements in Comparative Examples 42 to 44 were produced (see Table 7 below).

(Comparative Examples 45-47)
In Comparative Examples 14 to 16, the host material layer was formed using the compound (Host-1) instead of the compound (Host-2) as the host material. Each organic electroluminescent element in Examples 45 to 47 was produced (see Table 7 below).

(Comparative Examples 48-50)
In Comparative Examples 26 to 28, a comparison was made in the same manner as Comparative Examples 26 to 28 except that the host material layer was formed using the compound (Host-1) instead of the compound (Host-3) as the host material. Each organic electroluminescent element in Examples 48-50 was manufactured (see Table 7 below).

(Comparative Example 51)
In Comparative Example 20, the organic material in Comparative Example 51 was the same as Comparative Example 20 except that the host material layer was formed using the compound (Host-1) instead of the compound (Host-2) as the host material. An electroluminescent device was manufactured.

(Comparative Example 52)
In Comparative Example 32, the organic material in Comparative Example 52 was the same as Comparative Example 32 except that the host material layer was formed using the compound (Host-1) instead of the compound (Host-3) as the host material. An electroluminescent device was manufactured.

The main structures of the organic electroluminescent elements in Examples 19 to 24 and Comparative Examples 37 to 52 are summarized in Table 7 below. In addition, the numerical value in () in a table | surface shows thickness (nm).

(Measurement and evaluation method of heat resistance)
<Luminance half time (t ₂ / t ₁ , t ₃ / t ₁ )>
The organic electroluminescence device was driven from an initial luminance of 2,000 cd / m ^{2 in an} atmosphere of 10 ° C. until the luminance became 1,800 cd / m ² at the current density at the start of measurement.
Thereafter, the driven organic electroluminescence device was driven in each temperature atmosphere of 10 ° C., 55 ° C., and 70 ° C. until the luminance became 1,800 cd / m ² to 1,000 cd / m ² . The luminance half time from the start of measurement was measured.
At this time, the luminance half-time when driven in a constant atmosphere at 10 ° C. is t _1, and the luminance half-time when driven in a 55 ° C. atmosphere after driving in a 10 ° C. atmosphere is t _2. After driving under, the luminance half-life time when driving under the atmosphere at 70 ° C. was t _3, and the comparison was made according to the respective values of “t ₂ / t ₁ ” and “t ₃ / t ₁ ”.
Incidentally, the measurement of luminance, using a luminance measuring device (TOPCON _{Corporation),} the measurement of _{t 1, t 2, t 3} , was used durability evaluation device (EHC Co., Ltd.).

<Voltage increase value (ΔV) and luminance decrease value (ΔL)>
The organic electroluminescent element was energized for 3 hours at a current density of 1 mA / cm ² in a temperature atmosphere of 20 ° C., and then the temperature was increased from 20 ° C. to 70 ° C. with a gradient of 1 ° C./min. Holding for 3 hours in a temperature atmosphere and lowering the temperature to 20 ° C. with a gradient of 1 ° C./min as one cycle is repeated 100 cycles, and the voltage increase value of the drive voltage after 100 cycles with respect to the initial drive voltage (ΔV) was compared with the luminance decrease value (ΔL) after 100 cycles with respect to the initial luminance.
Note that a source measure unit 2400 manufactured by KEITHLEY was used for measuring the voltage value, and a luminance measuring apparatus used for measuring the luminance half-time was used for measuring the luminance.

Tables 8 and 8 below show the results of comparing the brightness half-life time, voltage increase value, and brightness decrease value of each organic electroluminescent element in Examples 1 to 3 and AD, and Comparative Examples 1 to 8 and AD. It is shown in 2. Here, the comparison of each item was performed by normalizing the organic electroluminescent element in Example 1 as 100.

As shown in Table 8 above, the organic electroluminescent elements in Examples 1 to 3 can significantly improve the heat resistance as compared with the organic electroluminescent elements in Comparative Examples 1 to 8.
Moreover, the organic electroluminescent element in Examples 1-3 can hold down the voltage rise value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 1-8, and is durable with respect to a temperature change. Are better.
Moreover, the organic electroluminescent element in Examples 1-3 can hold down the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 1-8, and is durable with respect to a temperature change. Are better.

As shown in Table 8-2 above, the organic electroluminescent elements in Examples A to D can significantly improve heat resistance as compared with the organic electroluminescent elements in Comparative Examples A to D.
Moreover, the organic electroluminescent element in Example AD can suppress the voltage rise value after applying a heat cycle lower than the organic electroluminescent element in Comparative Example AD, and is durable with respect to a temperature change. Are better.
Moreover, the organic electroluminescent element in Examples AD can suppress the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples AD, and is durable with respect to a temperature change. Are better.

Table 9 below shows the results of comparison of the luminance half-time, voltage increase value, and luminance decrease value of each organic electroluminescent element in Examples 4 to 6 and Comparative Examples 2 to 4 and 8 to 12. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 4 as 100.

As shown in Table 9 above, the organic electroluminescent elements in Examples 4 to 6 have significantly improved heat resistance than the organic electroluminescent elements in Comparative Examples 2 to 4 and 8 to 12.
Moreover, the organic electroluminescent element in Examples 4-6 can hold down the voltage rise value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 2-4 and 8-12, and a temperature change is carried out. Excellent durability against
Moreover, the organic electroluminescent element in Examples 4-6 can suppress the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 8-12, and is durable with respect to a temperature change. Are better.

Table 10 below shows the results of comparing the luminance half-life time, voltage increase value, and luminance decrease value of each organic electroluminescent element in Examples 7 to 9 and Comparative Examples 13 to 20. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 7 as 100.

As shown in Table 10 above, the organic electroluminescent elements in Examples 7 to 9 can significantly improve heat resistance as compared with the organic electroluminescent elements in Comparative Examples 13 to 20.
Moreover, the organic electroluminescent element in Examples 7-9 can hold down the voltage rise value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 13-20, and is durable with respect to a temperature change. Are better.
Moreover, the organic electroluminescent element in Examples 7-9 can suppress the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 13-20, and is durable with respect to a temperature change. Are better.

Table 11 below shows the results of comparison of the luminance half-time, voltage increase value, and luminance decrease value of each organic electroluminescent element in Examples 10-12 and Comparative Examples 14-16, 20-24. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 10 as 100.

As shown in Table 11 above, the organic electroluminescent elements in Examples 10 to 12 have significantly improved heat resistance than the organic electroluminescent elements in Comparative Examples 14 to 16 and 20 to 24.
Moreover, the organic electroluminescent element in Examples 10-12 can hold down the voltage rise value after carrying out a heat cycle lower than the organic electroluminescent element in Comparative Examples 14-16, 20-24, and a temperature change is carried out. Excellent durability against
Moreover, the organic electroluminescent element in Examples 10-12 can hold down the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 14-16, 20-24, and a temperature change is carried out. Excellent durability against

Table 12 below shows the results of comparing the luminance half-life time, the voltage increase value, and the luminance decrease value of each organic electroluminescent element in Examples 13 to 15 and Comparative Examples 25 to 32. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 13 as 100.

As shown in Table 12 above, the organic electroluminescent elements in Examples 13 to 15 can significantly improve the heat resistance as compared with the organic electroluminescent elements in Comparative Examples 25 to 32.
Moreover, the organic electroluminescent element in Examples 13-15 can hold down the voltage rise value after carrying out a thermal cycle lower than the organic electroluminescent element in Comparative Examples 25-32, and is durable with respect to a temperature change. Are better.
Moreover, the organic electroluminescent element in Examples 13-15 can suppress the brightness | luminance reduction value after applying a heat cycle lower than the organic electroluminescent element in Comparative Examples 25-32, and is durable with respect to a temperature change. Are better.

Table 13 below shows the results of comparison of the luminance half-time, voltage increase value, and luminance decrease value of each organic electroluminescent element in Examples 16 to 18 and Comparative Examples 26 to 28 and 32-36. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 16 as 100.

As shown in Table 13 above, the organic electroluminescent elements in Examples 16 to 18 have significantly improved heat resistance than the organic electroluminescent elements in Comparative Examples 26 to 28 and 32-36.
Moreover, the organic electroluminescent element in Examples 16-18 can hold down the voltage rise value after carrying out a thermal cycle lower than the organic electroluminescent element in Comparative Examples 26-28 and 32-36, and a temperature change is carried out. Excellent durability against
Moreover, the organic electroluminescent element in Examples 16-18 can hold down the brightness | luminance reduction value after carrying out a thermal cycle lower than the organic electroluminescent element in Comparative Examples 26-28 and 32-36, and a temperature change is carried out. Excellent durability against

Table 14 below shows the results of comparison of the luminance half-time, voltage increase value, and luminance decrease value of each organic electroluminescent element in Examples 19 to 24 and Comparative Examples 2 to 4, 8, and 37 to 52. Here, the comparison of each item was performed by standardizing the organic electroluminescent element in Example 19 as 100.
As shown in Table 14 above, the organic electroluminescent elements in Examples 19 to 24 have significantly improved heat resistance than the organic electroluminescent elements in Comparative Examples 2 to 4, 8, and 37 to 52.
Moreover, the organic electroluminescent element in Examples 19-24 has suppressed the voltage rise value after carrying out a heat cycle lower than the organic electroluminescent element in Comparative Examples 2-4, 8, 37-52, Excellent durability against temperature changes.
Moreover, the organic electroluminescent element in Examples 19-24 has suppressed the brightness | luminance reduction value after carrying out a thermal cycle lower than the organic electroluminescent element in Comparative Examples 2-4, 8, 37-52, Excellent durability against temperature changes.

  The organic electroluminescent device of the present invention has high heat resistance and excellent durability against temperature changes. For example, the display device, display, backlight, electrophotography, illumination light source, recording light source, exposure light source, reading light source, label It can be used for signboards, interiors, optical communications, etc., and can be suitably used for in-car displays of automobiles exposed to high temperature environments.

DESCRIPTION OF SYMBOLS 1 Anode 2 Hole injection layer 3 Hole transport layer 4 Host material layer 4a 1st host material layer 4b 2nd host material layer 5a 1st light emitting material dope layer 5b 2nd light emitting material dope layer 5c 3rd Light emitting material doped layer 6 Light emitting material undoped layer 6a First light emitting material undoped layer 6b Second light emitting material undoped layer 7 Electron transport layer 8 Electron injection layer 9 Cathode 10, 10 ′ Light emitting layer 100, 200, 300, 400, 500, 600 Organic electroluminescent device

Claims (5)

Light emitting layer having one light emitting material undoped layer between two light emitting material doped layers comprising a first light emitting material doped layer comprising a light emitting material and a host material comprising a styrylamine compound and a second light emitting material doped layer When,
A host material layer that is adjacent to at least one surface of the light emitting layer and is made of the same host material as the host material contained in the light emitting layer, and
An organic electroluminescent element, wherein the styrylamine compound is a blue light emitting material and contained in the light emitting material doped layer in an amount of 5 % by mass to 18 % by mass.   The organic electroluminescent element according to claim 1, wherein the host material layer is disposed adjacent to each of one surface of the light emitting layer and the other surface. The organic electroluminescent element according to claim 1, wherein the styrylamine compound is a compound represented by the following general formula (1).
However, in the general formula (1), Ar ₁ , Ar ₂ , Ar ₃ , Ar ₅ And Ar ₆ Each represents a hydrogen atom or an aryl group, and the aryl group is substituted with at least one of a linear or branched alkyl group, a substituted or unsubstituted aryl group and an amino group. Well, Ar ₄ Represents a substituted or unsubstituted arylene group. The organic electroluminescent element according to any one of claims 1 to 3, wherein the host material is at least one of an anthracene compound, a pyrene compound, and a chrysene compound. 5. The styryl compound and the host material contained in at least one of the light emitting material doped layers among the two light emitting material doped layers are any of the following (1) to (3). Organic electroluminescent element.
(1) The styrylamine compound is a compound (Dopant-1) represented by the following structural formula, and the host material is a compound (Host-1) represented by the following structural formula.
(2) The styrylamine compound is a compound (Dopant-3) represented by the following structural formula, and the host material is a compound (Host-2) represented by the following structural formula.
(3) The styrylamine compound is a compound (Dopant-5) represented by the following structural formula, and the host material is a compound (Host-3) represented by the following structural formula.