JP2011060722A - Organic electroluminescent device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent device having improved emitting strength and hue and a reduced change in chromaticity at a wide viewing angle. <P>SOLUTION: The organic electroluminescent device includes, at least, an organic electroluminescent element including at least a light-emitting layer between a pair of electrodes, and a light extraction member shaped as part of a half sphere that a sphere is split in half. The refractive index of the light-emitting layer is almost the same as that of the light extraction member, the light extraction member is located on the optical path of light emitted from the light-emitting layer, and the center of the light-emitting layer is at the same position as the center of the light extraction member. On the cross section perpendicular to the surface of the light-emitting layer at the center of the light extraction member, the light extraction member has a light extraction face cut out to be even with the bottom face of the light extraction member and parallel to the bottom face of the half sphere, wherein a vertical line is drawn at an angle of 0° from the light extraction member to the end of the surface of the light-emitting layer, a straight line is drawn at 60° to the vertical line from an intersection between the vertical line and the bottom face of the light extraction member to the same side of the light extraction member as the end of the surface of the light-emitting layer, and contact points between the straight line and an arcuate portion of the light extraction member are joined to each other via the straight line. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to an organic electroluminescent device.

  An organic electroluminescent device (hereinafter sometimes referred to as an “organic EL device”) is a self-luminous display device, and is used for displays and illumination. The organic EL display has advantages in display performance such as higher visibility than conventional CRTs and LCDs and no viewing angle dependency. There is also an advantage that the display can be reduced in weight and thickness. In addition to the advantages of light weight and thin layers, organic EL lighting has the possibility of realizing illumination in a shape that could not be realized so far by using a flexible substrate.

As described above, the organic EL device has excellent characteristics, but in general, the refractive index of each layer constituting the display device including the light emitting layer is higher than that of air (refractive index n = 1.0). For example, in an organic EL device, the refractive index of an organic thin film layer such as a light emitting layer is about n = 1.8. For this reason, both the top emission type and the bottom emission type have a problem in that the intensity (light quantity) emitted to the outside is limited by the total reflection angle caused by the difference in refractive index from the air layer.
In order to extract light confined by the total reflection angle, it is known to use a hemispherical lens as a light extraction member. By using the hemispherical lens, the light component reaching the surface of the emission layer is extracted. At that time, by making the refractive index of the hemispherical lens equal to the refractive index of the organic layer, there is no refractive index step, there is no loss of light confinement, and almost all light can be taken out. Incidentally, since the hemispherical lens has a refractive index equal to or higher than that of the organic layer, optical confinement loss in the organic layer is eliminated in principle.

Further, in an organic electroluminescent device, a microcavity structure that functions as a microresonator is formed in an organic electroluminescent element (hereinafter sometimes referred to as an “organic EL element”), thereby having a configuration without a microcavity structure. In comparison, the wavelength selectivity is improved, and the spectral half width is narrowed, so that the color tone is improved. Furthermore, since the wavelength is selected and the light intensity of the selected wavelength is increased, the luminance can be improved.
However, since the characteristics are sensitive to the film thickness of the layers that make up the resonator, when the light emitting part is observed from an inclined angle, there is an angular region where coherency is not maintained. Unlike the coherent, there is a problem that the color is shifted.
For this reason, there is a problem in that, by extracting all the components of light, the components of the spectrum that deteriorate the color that is not coherent are also extracted. For example, an organic EL display is required to have the same color from any angle, so this problem needs to be solved quickly.

So far, an organic EL element having a microresonator and a light shielding film has been proposed (see, for example, Patent Document 1). In this proposal, by having a light-shielding film that shields light emitted from the microresonator, light on the wide-angle side from a certain radiation angle is blocked and does not go outside. In the proposal, it is described that the light shielding film is provided corresponding to a portion where the optical length of the resonator varies, but the light shielding film functions to shield a wide-angle component of light that is substantially deteriorated in color. It is thought that there is. Therefore, the shade is improved by shielding the component having a poor color as compared with the case where the light shielding film is not used.
However, there is a problem that the luminance (radiation intensity) also decreases.

In addition, an organic EL element in which a bandpass filter layer is inserted in an organic layer sandwiched between reflective electrodes has been proposed (see, for example, Patent Document 2). In this proposal, the color selection system is improved by inserting a band-pass filter layer in the organic layer sandwiched between the reflective electrodes so that only a specific wavelength is reflected and transmitted.
In general, it is known that by incorporating a band-pass filter in an organic layer, absorption / transmission loss or the like occurs, and the radiation intensity tends to decrease.
In particular, in Patent Document 2, a band pass filter uses a filter having a wavelength characteristic that is transparent with respect to blue and has reflection characteristics with respect to green and red, and the band pass filter is laminated as a common layer on a three-color element. Therefore, there is a problem that the angle dependency of chromaticity with respect to a single color is not improved so much.

  Accordingly, the present situation is that rapid development of an organic electroluminescent device that is excellent in radiant intensity (luminance) and color and has little change in chromaticity over a wide viewing angle is required.

JP 2005-108736 A JP2007-335185A

  An object of the present invention is to solve the conventional problems and achieve the following objects. That is, an object of the present invention is to provide an organic electroluminescent device that is excellent in radiation intensity and color and has little change in chromaticity over a wide viewing angle.

  In order to solve the above-mentioned problems, the present inventors have made extensive studies and as a result, obtained the following findings. That is, the light emitting layer and the light extraction member have substantially the same refractive index, the light extraction member is positioned on the optical path of the light emitted from the light emission layer, and the center of the light emission layer and the light extraction member And the light extraction member draws a perpendicular line from the light extraction member to an end of the surface of the light emitting layer in a cross section perpendicular to the surface of the light emitting layer at the center of the light extraction member, The angle at this time is 0 °, and a straight line forming 60 ° from the perpendicular is formed on the same side as the end of the light emitting layer surface of the light extraction member from the intersection of the perpendicular and the bottom surface of the light extraction member. Pulling, connecting the straight line and the arc portion of the light extraction member with a straight line, cutting out the light extraction member in the horizontal direction with the bottom surface of the light extraction member, and a light extraction surface parallel to the bottom surface of the hemisphere By having Spectral components that are not coherent in light and have poor color can be confined to the inside by the total reflection angle so that they do not go out. It is the knowledge that can be done.

Means for solving the problems are as follows. That is,
<1> At least an organic electroluminescent element including at least a light emitting layer between a pair of electrodes, and a light extraction member having a shape of a part of a hemisphere obtained by dividing a sphere in half,
The light emitting layer and the light extraction member have substantially the same refractive index,
The light extraction member is located on an optical path of light emitted from the light emitting layer, and the center of the light emission layer and the center of the light extraction member are in the same position;
The light extraction member is
In a cross section perpendicular to the light emitting layer surface at the center of the light extraction member,
A perpendicular is drawn from the light extraction member to the end of the light emitting layer surface, and the angle at this time is set to 0 °.
From the intersection of the perpendicular and the bottom surface of the light extraction member, draw a straight line forming 60 ° from the perpendicular to the same side as the end of the light emitting layer surface of the light extraction member,
The contact points between the straight line and the arc portion of the light extraction member are connected by a straight line,
An organic electroluminescent device characterized by having a light extraction surface cut out in a horizontal direction with the bottom surface of the light extraction member and parallel to the bottom surface of the hemisphere.
<2> The organic electroluminescent device according to <1>, wherein the organic electroluminescent element has a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents an emission wavelength). .
<3> The light extraction member is
In the cross section perpendicular to the light emitting layer surface at the center of the hemisphere, the center of the hemisphere obtained by dividing the sphere in half and the center of the light emitting layer are in the same position.
A perpendicular is drawn from the hemisphere to the end of the light emitting layer surface, and the angle at this time is 0 °.
From the intersection of the perpendicular and the bottom surface of the hemisphere, a straight line forming 35 ° from the perpendicular is drawn on the opposite side of the light emitting layer surface of the hemisphere,
Connecting the straight line and the contact point of the arc of the hemisphere with a straight line,
The top of the sphere cut out horizontally with the bottom of the hemisphere,
The organic electroluminescence device according to any one of <1> to <2>, wherein the organic electroluminescence device is coaxially disposed on a light extraction surface.
<4> The ratio (A / B) of the area (A) of the surface of the light extraction member on the light emitting layer side and the area (B) of the surface of the light emission layer on the light extraction member side is 7 or more <1 The organic electroluminescence device according to any one of <3> to <3>.
<5> The organic electroluminescent device according to any one of <1> to <4>, wherein the organic electroluminescent element is a top emission type and has a sealing layer and a light extraction member in this order on one electrode. It is.
<6> The organic electroluminescent element is a bottom emission type, has a substrate, and the shape of each substrate on the light emitting layer is the shape of the light extraction member, any one of <1> to <4> It is an organic electroluminescent apparatus as described in above.

  ADVANTAGE OF THE INVENTION According to this invention, the various problems in the past can be solved, and an organic electroluminescence device that is excellent in radiation intensity and color and has little change in chromaticity over a wide viewing angle can be provided.

FIG. 1A is a schematic cross-sectional view for explaining an example of the shape of the light extraction member of the present invention, and is an explanatory view for cutting out the A shape. FIG. 1B is an example of the shape of the light extraction member of the present invention, and is a schematic cross-sectional view after being cut out in FIG. 1A (A shape). FIG. 2A is a schematic cross-sectional view for explaining an example of the shape of the light extraction member of the present invention, and is an explanatory view for cutting out a B shape. FIG. 2B is an example of the shape of the light extraction member of the present invention, and is a schematic cross-sectional view of a shape (C shape) obtained by combining the A shape and the B shape. FIG. 2C is an example of the shape of the light extraction member of the present invention, and is a schematic cross-sectional view of a shape (C shape) obtained by combining the A shape and the B shape. FIG. 3A is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 3B is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 3C is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 3D is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 3E is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 3F is a diagram illustrating an example of a light extraction member and a method for manufacturing an organic electroluminescent device. FIG. 3G is a diagram illustrating an example of a method of manufacturing a light extraction member and an organic electroluminescent device. FIG. 4 is a schematic cross-sectional view showing an example of the organic electroluminescent device of the present invention. FIG. 5 is a schematic cross-sectional view showing another example of the organic electroluminescent device of the present invention. FIG. 6 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (1) of Comparative Example 1 are plotted. FIG. 7 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (1) of Comparative Example 1 and the organic electroluminescent device (2) of Example 1 are plotted. FIG. 8 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (3) of Comparative Example 2 and the organic electroluminescent device (4) of Example 2 are plotted. FIG. 9 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (5) of Comparative Example 3 and the organic electroluminescent device (6) of Example 3 are plotted. FIG. 10 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (2) of Example 1 and the organic electroluminescent device (8) of Example 4 are plotted. FIG. 11 is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent device (7) of Comparative Example 4 and the organic electroluminescent device (2) of Example 1. FIG. 12A is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent device (2) of Example 1. FIG. FIG. 12B is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent element (8) of Example 4. FIG. 13 is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent devices (a) to (d) of Test Example 1.

(Organic electroluminescent device)
The organic electroluminescent device of the present invention includes at least an organic electroluminescent element and a light extraction member, and includes a substrate, a barrier layer, and other members as necessary.

<Organic electroluminescent device>
The organic electroluminescent element has at least a light emitting layer between a pair of electrodes (anode and cathode), and has a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, etc. as necessary. These layers may also have other functions. Various materials can be used for forming each layer.
The organic electroluminescent element is configured as a pixel including any one of red (R), green (G), and blue (B).
As a configuration of such a pixel, for example, as described in “Monthly Display”, September 2000, pages 33 to 37, the light emitting layer is made to emit light corresponding to red, green, or blue, respectively. A known structure such as a three-color light emitting method in which a pixel as a light emitting layer that emits light is formed and any one of these red, green, and blue pixels is arranged can be applied.

-Anode-
The anode supplies holes to a hole injection layer, a hole transport layer, a light emitting layer, and the like, and a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. The material preferably has a work function of 4 eV or more.
Examples of the material of the anode include conductive metal oxides such as tin oxide, zinc oxide, indium oxide, and indium tin oxide (ITO); metals such as gold, silver, chromium, and nickel; and these metals and conductive metals Examples thereof include mixtures or laminates with oxides, inorganic conductive substances such as copper iodide and copper sulfide; organic conductive materials such as polyaniline, polythiophene and polypyrrole, and laminates of these with ITO. Among these, a conductive metal oxide is preferable, and ITO is particularly preferable in terms of productivity, high conductivity, transparency, and the like.
There is no restriction | limiting in particular in the thickness of the said anode, Although it can select suitably according to material, 10 nm-5 micrometers are preferable, 50 nm-1 micrometer are more preferable, 100 nm-500 nm are still more preferable.

As the anode, for example, a layer formed on soda-lime glass, non-alkali glass, a transparent resin substrate or the like is used. When glass is used, it is preferable to use non-alkali glass 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.
The thickness of the substrate is not particularly limited as long as it is sufficient to maintain mechanical strength, and can be appropriately selected according to the purpose. However, when glass is used, 0.2 mm or more is preferable. 7 mm or more is more preferable.

  A barrier film can also be used as the transparent resin substrate. The barrier film is a film in which a gas impermeable barrier layer is provided on a plastic support. As the barrier film, a film in which silicon oxide or aluminum oxide is vapor-deposited (Japanese Patent Publication No. 53-12953, Japanese Patent Laid-Open No. 58-217344), an organic-inorganic hybrid coating layer (Japanese Patent Laid-Open No. 2000-323273, JP-A-2004-25732), those having an inorganic layered compound (JP-A-2001-205743), laminates of inorganic materials (JP-A-2003-206361, JP-A-2006-263389), organic Layers and inorganic layers laminated alternately (Japanese Patent Laid-Open No. 2007-30387, US Pat. No. 6,413,645, Affinito et al., Thin Solid Films 1996, pages 290-291), organic layers and inorganic layers are continuously formed. Laminated (US Patent Application Publication No. 2004-464) No. 97 specification) and the like.

  Various methods are used for the production of the anode. For example, in the case of ITO, electron beam method, sputtering method, resistance heating vapor deposition method, chemical reaction method (sol-gel method, etc.), dispersion of indium tin oxide A film is formed by a method such as application of an object. The anode can be subjected to cleaning or other processing to lower the driving voltage of the display device or to increase the light emission efficiency. For example, in the case of ITO, UV-ozone treatment is effective.

-Cathode-
The cathode supplies electrons to an electron injection layer, an electron transport layer, a light emitting layer, and the like. Adhesion between the cathode and adjacent layers such as an electron injection layer, an electron transport layer, and a light emitting layer, ionization potential, and stability It is selected in consideration of sex and the like.
As the material of the cathode, a metal, an alloy, a metal oxide, an electrically conductive compound, or a mixture thereof can be used. Specific examples thereof include alkali metals (for example, Li, Na, K, etc.) or fluorides thereof, Alkaline earth metals (eg Mg, Ca, etc.) or fluorides thereof, gold, silver, lead, aluminum, sodium-potassium alloys or mixed metals thereof, lithium-aluminum alloys or mixed metals thereof, magnesium-silver alloys or those thereof And a rare earth metal such as indium and ytterbium. Among these, a material having a work function of 4 eV or less is preferable, and aluminum, a lithium-aluminum alloy or a mixed metal thereof, a magnesium-silver alloy or a mixed metal thereof is particularly preferable.

There is no restriction | limiting in particular in the thickness of the said cathode, Although it can select suitably according to material, 10 nm-5 micrometers are preferable, 50 nm-1 micrometer are more preferable, 100 nm-1 micrometer are still more preferable.
As a method for producing the cathode, for example, an electron beam method, a sputtering method, a resistance heating vapor deposition method, a coating method, or the like is used, and a metal can be vapor-deposited alone or two or more components can be vapor-deposited simultaneously. Furthermore, a plurality of metals can be vapor-deposited simultaneously to form an alloy electrode, or a previously prepared alloy may be vapor-deposited.
The sheet resistance of the anode and cathode is preferably low, and is preferably several hundred Ω / □ or less.

-Light emitting layer-
The material of the light emitting layer is not particularly limited and may be appropriately selected depending on the purpose. Holes can be injected from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, and the cathode Alternatively, a layer having the function of injecting electrons from the electron injection layer, the electron transport layer, the function of moving the injected charge, and the function of emitting light by providing a field for recombination of holes and electrons is formed. What can be used can be used.

The material of the light emitting layer is not particularly limited and may be appropriately selected depending on the purpose. For example, benzoxazole derivatives, benzimidazole derivatives, benzothiazole derivatives, styrylbenzene derivatives, polyphenyl derivatives, diphenylbutadiene derivatives, tetra Phenylbutadiene derivatives, naphthalimide derivatives, coumarin derivatives, perylene derivatives, perinone derivatives, oxadiazole derivatives, aldazine derivatives, pyrazine derivatives, cyclopentadiene derivatives, bisstyrylanthracene derivatives, quinacridone derivatives, pyrrolopyridine derivatives, thiadiazolopyridine derivatives, Various metal complexes typified by metal complexes and rare earth complexes of cyclopentadiene derivatives, styrylamine derivatives, aromatic dimethylidin compounds, 8-quinolinol derivatives Polythiophene, polyphenylene, polyphenylene vinylene polymer compounds, and the like. These may be used individually by 1 type and may use 2 or more types together.
There is no restriction | limiting in particular in the thickness of the said light emitting layer, According to the objective, it can select suitably, 1 nm-5 micrometers are preferable, 5 nm-1 micrometer are more preferable, 10 nm-500 nm are still more preferable.
The method for forming the light emitting layer is not particularly limited and may be appropriately selected depending on the purpose. For example, resistance heating evaporation, electron beam, sputtering, molecular lamination method, coating method (spin coating method, casting method, dip method) Coating method, etc.) and LB method. Among these, resistance heating vapor deposition and a coating method are particularly preferable.

-Hole injection layer, hole transport layer-
The material of the hole injection layer and the hole transport layer has any one of a function of injecting holes from the anode, a function of transporting holes, and a function of blocking electrons injected from the cathode. If it is, there will be no restriction | limiting in particular, According to the objective, it can select suitably.
Examples of the material for the hole injection layer and the hole transport layer include carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamines. Derivatives, amino-substituted chalcone derivatives, styrylanthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, porphyrin compounds, polysilane compounds, poly Examples thereof include (N-vinylcarbazole) derivatives, aniline copolymers, thiophene oligomers, and conductive polymer oligomers such as polythiophene. These may be used individually by 1 type and may use 2 or more types together.

The hole injection layer and the hole transport layer may have a single-layer structure composed of one or more of the materials described above, or a multilayer structure composed of a plurality of layers having the same composition or different compositions. Good.
As a method for forming the hole injection layer and the hole transport layer, for example, a vacuum deposition method, an LB method, a method in which the hole injection / transport agent is dissolved or dispersed in a solvent (a spin coating method, a casting method, a dip method). Coating method). In the case of the coating method, it can be dissolved or dispersed together with the resin component.
The resin component is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyvinyl chloride resin, polycarbonate resin, polystyrene resin, polymethyl methacrylate resin, polybutyl methacrylate resin, polyester resin, polysulfone resin , Polyphenylene oxide resin, polybutadiene, poly (N-vinylcarbazole) resin, hydrocarbon resin, ketone resin, phenoxy resin, polyamide resin, ethyl cellulose, vinyl acetate resin, ABS resin, polyurethane resin, melamine resin, unsaturated polyester resin, alkyd Resin, epoxy resin, silicone resin, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.
The thicknesses of the hole injection layer and the hole transport layer are not particularly limited and may be appropriately selected depending on the purpose. For example, 1 nm to 5 μm is preferable, 5 nm to 1 μm is more preferable, and 10 nm to 500 nm is still more preferable. .

-Electron injection layer, electron transport layer-
As a material for the electron injection layer and the electron transport layer, any material may be used as long as it has any one of the function of injecting electrons from the cathode, the function of transporting electrons, and the function of blocking holes injected from the anode. There is no restriction | limiting, According to the objective, it can select suitably.
Examples of the material for the electron injection layer and the electron transport layer include triazole derivatives, oxazole derivatives, oxadiazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone derivatives, diphenylquinone derivatives, thiopyrandioxide derivatives, carbodiimide derivatives, Metal complexes of fluorenylidenemethane derivatives, distyrylpyrazine derivatives, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanine derivatives, 8-quinolinol derivatives, metal phthalocyanines, benzoxazole and benzothiazole ligands And various metal complexes represented by These may be used individually by 1 type and may use 2 or more types together.

The electron injection layer and the electron transport layer may have a single layer structure composed of one or more of the above-described materials, or may have a multilayer structure composed of a plurality of layers having the same composition or different compositions.
Examples of the method for forming the electron injection layer and the electron transport layer include a vacuum deposition method, an LB method, and a method in which the electron injection / transport agent is dissolved or dispersed in a solvent (a spin coating method, a casting method, a dip coating method, etc. ) Etc. are used. In the case of the coating method, it can be dissolved or dispersed together with the resin component, and as the resin component, for example, those exemplified in the case of the hole injection transport layer can be applied.
The thicknesses of the electron injection layer and the electron transport layer are not particularly limited and may be appropriately selected depending on the purpose. The thickness is preferably 1 nm to 5 μm, more preferably 5 nm to 1 μm, and still more preferably 10 nm to 500 nm.

The light emitting layer and the light extraction member to be described later have substantially the same refractive index.
Here, the substantially same means that the ratio of the refractive index of the light emitting layer to the refractive index of the light extraction member {(refractive index of the light emission layer) / (light extraction member)} is 0.9 to 1.1. I mean.
The ratio {(refractive index of light emitting layer) / (light extraction member)} is not particularly limited as long as it is 0.9 to 1.1, and can be appropriately selected according to the purpose. It is particularly preferably 95 to 1.05. When the ratio {(refractive index of the light emitting layer) / (light extraction member)} is less than 0.9 or exceeds 1.1, a difference in refractive index between the light emitting layer and the light extraction member is large. The light extraction efficiency may be reduced. On the other hand, when the ratio {(refractive index of the light emitting layer) / (light extraction member)} is within the particularly preferable range, it is advantageous in that the light extraction efficiency can be increased.

  Here, there is no restriction | limiting in particular as a structure of the said organic electroluminescent element, According to the objective, it can select suitably, For example, (1) The reflectance of the electrode (anode) of the light emission side in an organic electroluminescent element (2) The optical length of the microcavity structure, and (3) the structure corresponding to the bottom emission type or the top emission type.

As the electrode (anode) on the light emission side of the organic electroluminescence device of (1), in the bottom emission type, a transparent electrode (for example, ITO) having a reflectance of 10% or less as viewed from the light emitting layer, or the light emitting layer is used. A transflective electrode (for example, an Ag electrode) having a reflectance exceeding 10% can be used. If a transparent electrode is used as the anode, the microcavity structure cannot be formed because the reflection of light is weak. When a transflective electrode is used as the anode, a microcavity structure can be formed.
In the top emission type, a microcavity structure is formed by using a transflective electrode with a reflectance exceeding 10% as viewed from the light emitting layer as an electrode (anode) on the light emission side.

The optical length of the microcavity structure (2) can be appropriately adjusted by changing the thickness of the organic compound layer between the anode and the cathode constituting the organic electroluminescent element. Here, there is no restriction | limiting in particular as said organic compound layer, According to the objective, it can select suitably, For example, a hole transport layer, a hole injection layer, a light emitting layer, an electron transport layer, an electron injection layer, etc. are mentioned. .
Here, the macrocavity structure means a structure in which the light-transmitting side transflective layer interferes with the light-exiting reflective layer.

The optical length (optical distance) L of the microcavity structure is represented by L = 2 × Σn _i d _i (where i represents an integer from 1 to i in the number of layers) and a phase shift due to reflection, It is represented by the sum of the products of the thickness d of each layer formed between the cathodes and the refractive index n of the layer.
The optical length L is related to the emission wavelength λ by the optical length L (λ) = mλ (m = 1: 1, m = 2: secondary, m = 3: 3rd), and the optical length. L (λ) is represented by the following mathematical formula.
Where L (λ) is the optical length [= 2Σn _j d _j + ΣABS (φmiλ / 2π)], λ is the emission wavelength, i is a suffix indicating the metal reflective layer, and j is other than the metal reflective layer. The suffix indicating the layer between the metal layers (organic layer, dielectric layer, etc.) is shown.

The microcavity structure is primary when the optical length L (λ) is 1λ (where λ represents the light emission wavelength), and the minimum optical that is a condition for strengthening the light that round-trips between the metal reflective layers. Means long.
When the microcavity structure is secondary, the optical length L (λ) is 2λ (where λ represents the emission wavelength), and the minimum optical condition under which the light that round-trips between the metal reflective layers is intensified. It means that the optical length is the second shortest from the longest.
When the microcavity structure is third order, the optical length L (λ) is 3λ (where λ represents the light emission wavelength), and the minimum optical condition under which the light that round-trips between the metal reflecting layers is intensified. It means that the optical length is the third shortest from the longest.

  It is advantageous that the organic electroluminescent element has a microcavity structure in terms of excellent radiation intensity and color. Among them, the front-side radiation intensity is equal when having a secondary microcavity structure with an optical length L (λ) of 2λ (where λ represents an emission wavelength) compared to the primary microcavity structure. Otherwise, the resonance effect is more remarkable and the spectrum is sharp and the color is good. Further, when compared with a third-order microcavity structure, it is advantageous in that the front radiation intensity is greatly superior. Further, in the microcavity structure higher than the third order, the extracted light intensity is in a direction to attenuate due to the reason of the resonance structure. As for the film formation, the primary microcavity structure requires a thin film design, which is difficult to manufacture compared to the secondary microcavity structure, and the secondary microcavity structure is advantageous also in this respect.

<Light extraction member>
The light extraction member has a shape of a part of a hemisphere obtained by dividing a sphere in half.
The light extraction member is located on an optical path of light emitted from the light emitting layer, and the center of the light emission layer and the center of the light extraction member are at the same position.
One light extraction member is arranged per pixel.

The surface on which the light extraction member is disposed is located on the optical path of the light emitted from the light emitting layer, and the center of the light emitting layer and the center of the light extraction member are at the same position. There is no restriction | limiting in particular, According to the objective, it can select suitably.
In the bottom emission type, for example, on a glass substrate, the shape of the light emitting member at the position on each light emitting layer of the substrate is the shape of the light extraction member. The refractive index of the bottom glass substrate is substantially the same as that of the light emitting layer. It is preferable in that it is a material having a refractive index of 5 mm, and the bottom surface of the light extraction member shape and the semi-transmissive metal layer have a very close distance configuration.
In the top emission type, the sealing layer is preferable because it can be disposed directly on the organic layer from which light is extracted.

The shape of the light extraction member will be described with reference to FIGS. 1A and 1B.
1A and 1B are schematic views of a cross section perpendicular to the light emitting layer surface at the center of the light extraction member. 1A and 1B, reference numeral 1 denotes a hemispherical lens, reference numeral 2 denotes a light emitting layer, and reference numeral 3 denotes a light extraction member which is an embodiment of the present invention after cutting out the hemispherical lens.

  The light extraction member has a perpendicular line (reference numeral “4”) from the light extraction member to an end portion of the light emission layer surface in a cross section perpendicular to the light emission layer surface at the center (reference numeral “8”) of the light extraction member. The angle at this time is 0 °, and 60 ° from the perpendicular is formed on the same side as the end of the light emitting layer surface of the light extraction member from the intersection of the perpendicular and the bottom surface of the light extraction member. A straight line (symbol “5”) is drawn, and a contact point (symbol “6”) between the straight line and the arc portion of the light extraction member is connected by a straight line (symbol “7”), and the bottom surface of the light extraction member It has a light extraction surface that is cut out in the horizontal direction and parallel to the bottom surface of the hemisphere (see FIG. 1B, hereinafter may be referred to as “A shape”).

  By adopting the shape described above, the boundary surface (light extraction surface) with the air of the spectral component in the angular range where the color tone at the viewing angle deteriorates is flattened to be a total reflection region, and the spectral component in the angular range where the color tone becomes poor (35 ° -60 °) can be cut. Then, by applying the arc form of the hemispherical lens (form in which the incident angle component is perpendicularly incident) in an angle range other than the angle range in which the color tone is deteriorated, the spectral component in the angle range with good color tone (After 60 ° (wide angle side)) can be taken out, and the change in chromaticity can be reduced over a wide viewing angle. Further, on the wide angle side, the luminance can be improved as compared with the case where the light extraction member is not used.

The shape of the light extraction member is more preferably the following shape.
A more preferable shape of the light extraction member will be described with reference to FIGS.

  2A to 2C are schematic views of cross sections perpendicular to the light emitting layer surface at the center of the light extraction member. 2A to 2C, reference numeral 1 denotes a hemispherical lens, reference numeral 2 denotes a light emitting layer, and reference numeral 3 denotes a light extraction member which is an embodiment of the present invention after cutting out the hemispherical lens.

  2B and 2C, the center of the hemisphere obtained by dividing the sphere in half and the center of the light emitting layer are in the same position, and the center of the hemisphere (reference numeral “8”) In a cross section perpendicular to the surface of the light emitting layer (see FIG. 2A), a perpendicular (reference numeral “4”) is drawn from the hemisphere to the end of the surface of the light emitting layer, the angle at this time is 0 °, A straight line (symbol “9”) that forms 35 ° from the perpendicular is drawn from the intersection with the bottom of the hemisphere to the opposite side of the light emitting layer surface of the hemisphere, and the straight line and the arc portion of the hemisphere Are connected to each other (symbol “10”) by a straight line (symbol “11”), and the top of the sphere (hereinafter also referred to as “B shape”) cut out in the horizontal direction from the bottom surface of the hemisphere is light. It is arranged coaxially on the take-out surface.

  In the B shape, a spectral component (within 35 ° (narrow angle side)) having a good angle range can be taken out. Further, by making the light extraction member a C shape that combines the A shape and the B shape, the change in chromaticity can be reduced over a wide viewing angle, and the radiation intensity compared to the A shape. Can be further improved.

  The ratio (A / B) of the area (A) of the surface of the light extraction member on the light emitting layer side to the area (B) of the surface of the light emission layer on the light extraction member side is not particularly limited. Depending on the situation, it can be selected appropriately, but 7 or more is particularly preferred. When the ratio (A / B) is less than 7, the lens condensing effect may contribute only to a part of the emitted light, and the effect may be reduced. For example, this ratio is large, for example, exceeds 20. This means that the emission size is relatively small, which leads to a decrease in luminance.

  There is no restriction | limiting in particular as a material of the said light extraction member, According to the objective, it can select suitably, For example, transparent resin, glass, a transparent crystal, a transparent ceramic etc. are mentioned.

There is no restriction | limiting in particular as a preparation method of the said light extraction member, According to the objective, it can select suitably, For example, cutting, the inkjet method, the imprint method, the photolithographic method etc. are mentioned.
In the imprint method, for example, a composition containing a release agent and a UV curable resin is applied onto a transparent mold formed so that the light extraction member can be formed, and then the transparent mold is placed on the organic electroluminescent element. The light extraction member can be formed on the organic electroluminescent light emitting device by pressure-bonding and irradiating with UV light and then releasing the mold.
Moreover, in a bottom emission type | mold, it can produce in the process as shown to FIG. 3A-FIG. 3G, for example. That is, the water repellent material 13 and the resist (negative) 14 are laminated on the glass substrate 12 in this order (see FIG. 3B). Next, dry etching is performed under conditions that match the etching rates of the resist 14 and the glass substrate 12 to form hemispheres 15 at positions on the light emitting layers on the glass substrate (see FIGS. 3C and 3D). Then, the said hemispherical part can be grind | polished with the grinding | polishing sheet | seat 16, and the shape of a light extraction member can be formed on a glass substrate (refer FIG. 3E and FIG. 3F). In this case, an organic electroluminescent device is obtained by forming an organic electroluminescent element on the surface of the glass substrate opposite to the surface on which the shape 20 of the light extraction member is formed (FIG. 3G). In FIG. 3G, reference numeral 17 indicates a reflective electrode, reference numeral 18 indicates an organic compound layer, and reference numeral 19 indicates a semi-transmissive electrode.

-Barrier layer (sealing layer)-
The barrier layer is not particularly limited as long as it has a function of preventing permeation of oxygen, moisture, nitrogen oxides, sulfur oxides, ozone and the like in the atmosphere, and can be appropriately selected according to the purpose.
There is no restriction | limiting in particular as a material of the said barrier layer, According to the objective, it can select suitably, For example, SiN, SiON, etc. are mentioned.
There is no restriction | limiting in particular as thickness of the said barrier layer, Although it can select suitably according to the objective, 5 nm-1,000 nm are preferable, 7 nm-750 nm are more preferable, 10 nm-500 nm are especially preferable. If the thickness of the barrier layer is less than 5 nm, the barrier function for preventing the permeation of oxygen and moisture in the air may be insufficient. If the thickness exceeds 1,000 nm, the light transmittance decreases and the transparency is reduced. May be damaged.
As for the optical properties of the barrier layer, the light transmittance is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.
There is no restriction | limiting in particular as a formation method of the said barrier layer, According to the objective, it can select suitably, For example, CVD method, a vacuum evaporation method, etc. are mentioned.

-Board-
There is no restriction | limiting in particular about the material, a shape, a structure, a magnitude | size, etc. as said board | substrate, According to the objective, it can select suitably, As a shape of the said board | substrate, it is preferable that it is 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 light emitting layer.

  The material for the substrate is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include inorganic materials such as yttria-stabilized zirconia (YSZ) and glass; polyethylene terephthalate, polybutylene phthalate, polyethylene naphthalate, and the like. Examples thereof include organic materials such as polyester, polystyrene, polycarbonate, polyethersulfone, polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene). These may be used individually by 1 type and may use 2 or more types together.

  When glass is used as the substrate, it is preferable to use non-alkali glass 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 (for example, barrier film board | substrate). 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.

  When the thermoplastic substrate is used, a hard coat layer, an undercoat layer, or the like may be further provided as necessary.

  Here, FIG. 4 is a schematic cross-sectional view showing a bottom emission type organic electroluminescent device which is an example of the organic electroluminescent device of the present invention. FIG. 5 is a schematic cross-sectional view showing a top emission type organic electroluminescent device which is an example of the organic electroluminescent device of the present invention.

The bottom emission type organic electroluminescent device 100 of FIG. 4 has an organic electroluminescent element 101 (anode 51, hole injection layer 52, hole transport layer 53, light emitting layer 54, electron transport layer 55, electron injection) on a glass substrate 61. A light extraction member 58 is formed on a glass substrate 61 as a light extraction surface.
The top emission type organic electroluminescent device 200 of FIG. 5 is formed on a glass substrate 61 with an organic electroluminescent element 201 (cathode 62, hole injection layer 63, first hole transport layer 64, second hole transport layer 65, A light emitting layer 66, a first electron transport layer 67, a second electron transport layer 68, an electron injection layer 69, anodes 70 and 71), and a barrier layer 72 so as to cover the organic electroluminescent element on the substrate. A light extraction member 73 is formed on the barrier layer 72 as a light extraction surface.
The “light emission direction” indicates a direction in which light from the light emitting layer is emitted from the light extraction surface to the outside of the organic electroluminescence device. In the case of the bottom emission type organic electroluminescent device 100 shown in FIG. 4, as indicated by the arrow, the direction toward the lower side in parallel with the drawing as viewed from the light emitting layer 54 is shown. In the case of the top emission type organic electroluminescent device 200 shown in FIG. 5, as indicated by an arrow, the direction from the light emitting layer 66 toward the upper side in parallel with the drawing is shown.

  The organic electroluminescent device of the present invention may be configured as a device capable of displaying in full color. As a method for making the organic electroluminescence device of the present invention of a full color type, for example, as described in “Monthly Display”, September 2000, pages 33 to 37, the three primary colors (blue (B ), Green (G), red (R)), each of which emits light corresponding to a three-color light emitting method in which a layer structure for emitting light corresponding to each of the light emitting layers is arranged on a substrate. A white method, a color conversion method for converting blue light emission by a blue light emission layer structure into red (R) and green (G) through a fluorescent dye layer, and the like are known.

  In addition, by using a combination of a plurality of layer structures of different emission colors obtained by the above method, a planar light source having a desired emission color can be obtained. For example, a white light-emitting light source that combines blue and yellow light-emitting elements, a white light-emitting light source that combines blue, green, and red light-emitting elements.

  The organic electroluminescent device of the present invention includes, for example, a computer, an on-vehicle display, an outdoor display, a household device, a commercial device, a household appliance, a traffic display, a clock display, a calendar display, a luminescent It can be suitably used in various fields including screens and audio equipment.

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

(Comparative Example 1)
<Production of organic electroluminescent device (1)>
-Production of organic electroluminescent device (1)-
A top emission type organic electroluminescence device was produced as follows.

As a glass substrate, Eagle 2000 (manufactured by Corning) having a thickness of 0.7 mm and a refractive index of 1.5 was used.
Next, aluminum (Al) as a cathode was formed on the glass substrate by vacuum deposition so as to have a thickness of 100 nm.
Next, on the Al film, as a hole injection layer, 2-TNATA [4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine] and MoO ₃ are in a ratio of 7: 3 with a thickness of 20 nm. It formed by vacuum vapor deposition so that it might become.
Next, the hole injection layer is doped with 1.0% F4-TCNQ (2, 3, 5, 6-tetrafluoro-7, 7, 8, 8 tetracyanoquinodimethane) as 2-TNATA as the first hole transport layer. It formed by vacuum vapor deposition so that it might become a thickness of 141 nm.
Next, α-NPD [N, N ′-(dinaphthylphenylamino) pyrene] is formed as a second hole transport layer on the first hole transport layer by vacuum deposition so as to have a thickness of 10 nm. did.

Next, on the second hole transport layer, a light emitting layer is formed using CBP (4,4′-dicarbazole-biphenyl) as a host material, and a light emitting material A represented by the following structural formula as a light emitting material, 85: It was formed by vacuum co-evaporation so that the thickness was 30 nm at a ratio of 15.

Next, BAlq (Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate) is formed as a first electron transport layer on the light emitting layer by vacuum deposition so as to have a thickness of 49 nm. did.
Next, on the first electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenthrolin) is formed as a second electron transport layer so that the thickness becomes 1.0 nm. And formed by vacuum evaporation.
Next, LiF as an electron injection layer was formed on the second electron transport layer by vacuum deposition so as to have a thickness of 1.0 nm.
Next, Al is formed as an anode on the electron injection layer by vacuum deposition so that the thickness is 1.5 nm, and Ag is further formed on the Al by vacuum deposition so that the thickness is 20 nm. did. The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
The organic electroluminescent element (1) was produced by the above.
The obtained organic electroluminescent element (1) had a secondary microcavity structure with an optical length L (λ) of 2λ (where λ represents an emission wavelength).

The produced organic electroluminescent element (1) was optimized for light emission of green (about 530 nm), and the area of the light emitting portion (light emitting layer) of the organic electroluminescent element was 2 mm × 2 mm.
The refractive index of the light emitting layer of the organic electroluminescent element was about 1.8.

-Production of organic electroluminescent device (1)-
As shown in FIG. 5, a SiON layer as a barrier layer was formed to a thickness of 2,000 nm by vacuum deposition so as to cover the organic electroluminescent element (1) on the substrate.

On the barrier layer, a hemispherical lens (the diameter of the light emitting layer side surface is 10 mm, the height from the light emitting layer side surface to the top is about 2 mm, and the refractive index is 1.8) is formed on the barrier layer. The center of the light emitting layer of the electroluminescent element and the center of the hemispherical lens were arranged at the same position. The lens was fixed (adhered) by thinly applying a UV adhesive on the barrier layer, and then irradiating the hemispherical lens with UV light. As the UV adhesive, T-857 / UR009 manufactured by Nagase Sangyo was used.
As a result, light is extracted outside until about 33 °, which is the total reflection angle at the boundary with air (refractive index n = 1.0).

-Fabrication of hemispherical lens-
The hemispherical lens was produced by cutting and polishing a hemispherical material (material: glass type name FD60 manufactured by HOYA Corporation).

Example 1
<Production of organic electroluminescent device (2)>
An organic electroluminescent device (2) was produced in the same manner as in Comparative Example 1 except that the hemispherical lens in Comparative Example 1 was replaced with the light extraction member having the shape of FIG. 1B.

The light extraction member having the shape of FIG. 1B is perpendicular to the end of the surface of the light emitting layer from the hemisphere in a cross section perpendicular to the surface of the light emitting layer at the center (reference numeral “8”) of the hemispherical lens of Comparative Example 1. (4)), the angle at this time is set to 0 °, and 60 ° from the perpendicular to the same side as the end of the light emitting layer surface of the hemisphere from the intersection of the perpendicular and the bottom of the hemisphere. A straight line (symbol “5”) is formed, and the contact point (symbol “6”) between the straight line and the arc portion of the hemisphere is connected by a straight line (symbol “7”), and the bottom surface of the light extraction member It has a light extraction surface cut out in the horizontal direction and parallel to the bottom surface of the hemisphere (hereinafter sometimes referred to as “A shape”).
The light extraction member has a bottom surface diameter of 10 mm and a height from the bottom surface to the light extraction surface of 2.3 mm.

The A-shaped light extraction member was produced as follows.
A hemispherical material made of the same material as in Comparative Example 1 was prepared by grinding with a glass material and polishing so that the height from the bottom surface to the light extraction surface was 2.3 mm.

(Comparative Example 2)
<Production of organic electroluminescent device (3)>
-Preparation of organic electroluminescent device (2)-
As a glass substrate, Eagle 2000 (manufactured by Corning) having a thickness of 0.7 mm and a refractive index of 1.5 was used.
Next, aluminum (Al) as a cathode was formed on the glass substrate by vacuum deposition so as to have a thickness of 100 nm.
Next, on the Al film, as a hole injection layer, 2-TNATA [4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine] and MoO ₃ are in a ratio of 7: 3 with a thickness of 20 nm. It formed by vacuum vapor deposition so that it might become.
Next, the hole injection layer is doped with 1.0% F4-TCNQ (2, 3, 5, 6-tetrafluoro-7, 7, 8, 8 tetracyanoquinodimethane) as 2-TNATA as the first hole transport layer. It formed by vacuum vapor deposition so that it might become a thickness of 195 nm.
Next, α-NPD [N, N ′-(dinaphthylphenylamino) pyrene] is formed as a second hole transport layer on the first hole transport layer by vacuum deposition so as to have a thickness of 10 nm. did.

Next, on the second hole transport layer, a light-emitting layer is formed using mCP (1,3-bis (carbazol-9-yl) benzene as a host material and a light-emitting material B represented by the following structural formula as a light-emitting material. , 94: 6, and vacuum co-evaporation so that the thickness is 30 nm.

Next, BAlq (Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate) is formed as a first electron transport layer on the light emitting layer by vacuum deposition so that the thickness is 39 nm. did.
Next, on the first electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenthrolin) is formed as a second electron transport layer so that the thickness becomes 1.0 nm. And formed by vacuum evaporation.
Next, LiF as an electron injection layer was formed on the second electron transport layer by vacuum deposition so as to have a thickness of 1.0 nm.
Next, Al is formed as an anode on the electron injection layer by vacuum deposition so that the thickness is 1.5 nm, and Ag is further formed on the Al by vacuum deposition so that the thickness is 20 nm. did. The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
Thus, an organic electroluminescent element (2) was produced.
The obtained organic electroluminescent element (2) had a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents an emission wavelength).

The produced organic electroluminescent element (2) was optimized for red (about 630 nm) light emission, and the area of the light emitting portion (light emitting layer) of the organic electroluminescent element was 2 mm × 2 mm.
The refractive index of the light emitting layer of the organic electroluminescent element was about 1.8.

-Production of organic electroluminescent device (3)-
In the production of the organic electroluminescent device (1) of Comparative Example 1, an organic electroluminescent device (1) was prepared in the same manner as Comparative Example 1 except that the organic electroluminescent device (1) was replaced with the organic electroluminescent device (2). 3) was produced.

(Example 2)
<Production of organic electroluminescent device (4)>
In the production of the organic electroluminescent device (2) of Example 1, the same procedure as in Example 1 was conducted except that the organic electroluminescent element (1) was replaced with the organic electroluminescent element (2) produced in Comparative Example 2. Thus, an organic electroluminescent device (4) was produced.

(Comparative Example 3)
<Preparation of organic electroluminescent device (5)>
-Preparation of organic electroluminescent device (3)-
As a glass substrate, Eagle 2000 (manufactured by Corning) having a thickness of 0.7 mm and a refractive index of 1.5 was used.
Next, aluminum (Al) as a cathode was formed on the glass substrate by vacuum deposition so as to have a thickness of 100 nm.
Next, on the Al film, as a hole injection layer, 2-TNATA [4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine] and MoO ₃ are in a ratio of 7: 3 and the thickness is 10 nm. It formed by vacuum vapor deposition so that it might become.
Next, the hole injection layer is doped with 1.0% F4-TCNQ (2, 3, 5, 6-tetrafluoro-7, 7, 8, 8 tetracyanoquinodimethane) as 2-TNATA as the first hole transport layer. It formed by vacuum vapor deposition so that it might become a thickness of 120 nm.
Next, α-NPD [N, N ′-(dinaphthylphenylamino) pyrene] is formed as a second hole transport layer on the first hole transport layer by vacuum deposition so as to have a thickness of 10 nm. did.

Next, on the second hole transport layer, a light emitting layer is formed by using mCP (1,3-bis (carbazol-9-yl) benzene as a host material, and a light emitting material C represented by the following structural formula as a light emitting material. , 87:13, and the thickness was 33 nm by vacuum co-evaporation.

Next, BAlq (Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate) is formed as a first electron transport layer on the light emitting layer by vacuum deposition so as to have a thickness of 29 nm. did.
Next, on the first electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenthrolin) is formed as a second electron transport layer so that the thickness becomes 1.0 nm. And formed by vacuum evaporation.
Next, LiF as an electron injection layer was formed on the second electron transport layer by vacuum deposition so as to have a thickness of 1.0 nm.
Next, Al is formed as an anode on the electron injection layer by vacuum deposition so that the thickness is 1.5 nm, and Ag is further formed on the Al by vacuum deposition so that the thickness is 20 nm. did. The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
Thus, an organic electroluminescent element (3) was produced.
The obtained organic electroluminescent element (3) had a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents a light emission wavelength).

The produced organic electroluminescent element (3) was optimized for light emission of blue (about 470 nm), and the area of the light emitting portion (light emitting layer) of the organic electroluminescent element was 2 mm × 2 mm.
The refractive index of the light emitting layer of the organic electroluminescent element was about 1.8.

-Production of organic electroluminescent device (5)-
In the production of the organic electroluminescent device (1) of Comparative Example 1, an organic electroluminescent device (1) was prepared in the same manner as Comparative Example 1 except that the organic electroluminescent device (1) was replaced with the organic electroluminescent device (3). 5) was produced.

(Example 3)
<Production of organic electroluminescent device (6)>
In the production of the organic electroluminescent device (2) of Example 1, the same procedure as in Example 1 was conducted except that the organic electroluminescent element (1) was replaced with the organic electroluminescent element (3) produced in Comparative Example 3. Thus, an organic electroluminescent device (6) was produced.

(Comparative Example 4)
<Production of organic electroluminescent device (7)>
An organic electroluminescence device (7) was produced in the same manner as in Comparative Example 1 except that no hemispherical lens was used in the production of the organic electroluminescence device (1) of Comparative Example 1.

Example 4
<Preparation of organic electroluminescent device (8)>
An organic electroluminescent device (8) was produced in the same manner as in Example 1, except that the light extraction member in Example 1 was replaced with the light extraction member (C shape) having the shape of FIG. 2C.

The light extraction member having the shape of FIG. 2C has a section (see FIG. 2A) perpendicular to the surface of the light emitting layer at the center of the hemisphere (reference numeral “8”) obtained by dividing the sphere in half, from the hemisphere to the surface of the light emitting layer. A perpendicular (reference numeral “4”) is drawn to the end, the angle at this time is 0 °, and from the intersection of the normal and the bottom of the hemisphere, on the side opposite to the end of the light emitting layer surface of the hemisphere, A straight line (symbol “9”) forming 35 ° is drawn from the perpendicular, and the contact points (symbol “10”) between the straight line and the arc portion of the hemisphere are connected by a straight line (symbol “11”), and the hemisphere A sphere top portion (hereinafter also referred to as “B shape”) cut out in the horizontal direction with the bottom surface of the light source is coaxially disposed on the light extraction surface of the light extraction member (A shape) of Example 1. (Refer to FIGS. 2B and 2C, hereinafter referred to as “C shape”) .)
In the B shape, the diameter of the surface on the A shape side is 2 mm, and the height from the surface on the A shape side to the top is 0.2 mm.

The light extraction member (C shape) was produced as follows.
The A-shaped member and the B-shaped member were separately prepared by cutting and polishing. Next, the B-shaped member was bonded so as to be coaxially disposed on the A-shaped light extraction surface, thereby producing the C-shaped light extraction member.
The bonding was performed with an adhesive (trade name, manufactured by Opstar JSR). In addition, you may perform the said bonding by the heat sealing | fusion of glass material.

<Evaluation>
The following evaluation was performed about the organic electroluminescent apparatus obtained by the said Example and the comparative example.

-Change in chromaticity depending on viewing angle-
CIE chromaticity at each angle of the organic electroluminescent device (a perpendicular line is drawn from the light extraction surface of the light extraction member to the light emitting layer, and the viewing angle viewed from this direction is 0 °, and ± 5 ° in increments of 5 °). The coordinates u ′ and v ′ were determined based on the CIE 1976 standard from the x and y chromaticity coordinates calculated from the spectrum.

FIG. 6 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (1) of Comparative Example 1 are plotted.
From the results of FIG. 6, it was found that in the organic electroluminescent device (1) of Comparative Example 1 using a hemispherical lens, the chromaticity change was large in the angle range of 35 ° to 60 °.

FIG. 7 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (1) of Comparative Example 1 and the organic electroluminescent device (2) of Example 1 are plotted.
From the results of FIG. 7, it was found that the chromaticity change near 50 ° was suppressed in the organic electroluminescent device (2) of Example 1 using the light extraction member (A shape) of the present invention.

FIG. 8 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (3) of Comparative Example 2 and the organic electroluminescent device (4) of Example 2 are plotted.
From the result of FIG. 8, it was found that the chromaticity change around 40 ° was suppressed in the organic electroluminescent device (4) of Example 2 using the light extraction member (A shape) of the present invention.

FIG. 9 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (5) of Comparative Example 3 and the organic electroluminescent device (6) of Example 3 are plotted.
From the results of FIG. 9, it was found that the chromaticity change near 55 ° was suppressed in the organic electroluminescent device (6) of Example 3 using the light extraction member (A shape) of the present invention.

FIG. 10 is a diagram in which u ′ and v ′ of CIE chromaticity coordinates at each angle of the organic electroluminescent device (2) of Example 1 and the organic electroluminescent device (8) of Example 4 are plotted.
From the result of FIG. 10, it can be seen that in the organic electroluminescent device (8) of Example 4 using the light extraction member (C shape) of the present invention, the chromaticity change in the vicinity of 40 ° to 55 ° is suppressed. It was.

−Radiation intensity (luminance) −
Radiation intensity and angle at each angle of the organic electroluminescent device (perpendicular lines are drawn from the light extraction surface of the light extraction member to the light emitting layer, and the viewing angle viewed from this direction is 0 °, up to ± 90 °) The light spectrum was measured with a luminance meter (CS-2000 manufactured by Konica Minolta).

FIG. 11 is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent device (7) of Comparative Example 4 and the organic electroluminescent device (2) of Example 1.
From the result of FIG. 11, in the organic electroluminescent device (2) of Example 1 using the light extraction member (A shape) of the present invention, the radiation intensity is on the wide angle side (greater than 60 °, smaller than −60 °). It turns out that it has improved.

FIG. 12A shows the result of measuring the radiation intensity at each angle of the organic electroluminescent device (2) of Example 1, and FIG. 12B shows the radiation intensity at each angle of the organic electroluminescent device (8) of Example 4. It is a figure which shows the measurement result. In addition, the radiant intensity of the vertical axis | shaft of FIG. 12A and FIG. 12B is an arbitrary unit, and is the same conditions.
From the results of FIGS. 12A and 12B, in the organic electroluminescent device (8) of Example 4 using the light extraction member (C shape) of the present invention, Example 1 using the light extraction member (A shape) of the present invention. It was found that the radiation intensity was improved from the organic electroluminescent device (2).

(Test Example 1: Examination of ratio (A / B))
The ratio (A / B) between the area (A) of the surface of the light extraction member on the light emitting layer side and the area (B) of the surface of the light extraction layer on the light extraction member side was examined.

<Manufacture of organic electroluminescent device (a)>
In the same manner as in Comparative Example 1, an organic electroluminescent device (a) was produced.
In the organic electroluminescent device (a), the diameter of the surface on the light emitting layer side of the light extraction member is 10 mm, and the area (A) is 78.5 mm ² . Moreover, the area (B) of the surface at the side of the light extraction member of a light emitting layer is 4 mm < ² >.

<Manufacture of organic electroluminescent device (b)>
In the manufacture of the organic electroluminescence device (a), the light extraction member is replaced with a light extraction member having a diameter of 3 mm on the surface of the light emitting layer. Thus, an organic electroluminescent device (b) was produced.

<Manufacture of organic electroluminescent device (c)>
In the production of the organic electroluminescence device (a), the light extraction member was replaced with a light extraction member having a diameter of 4 mm on the surface of the light emitting layer, and was the same as the production of the organic electroluminescence device (a). Thus, an organic electroluminescent device (c) was produced.

<Manufacture of organic electroluminescent device (d)>
In the production of the organic electroluminescence device (a), the light extraction member is replaced with a light extraction member having a diameter of 6 mm on the surface on the light emitting layer side, and is the same as the production of the organic electroluminescence device (a). Thus, an organic electroluminescent device (d) was produced.

Table 1 shows the configurations of the organic electroluminescent devices (a) to (d).

−Radiation intensity (luminance) −
Each angle of the organic electroluminescent devices (a) to (d) (a perpendicular line is drawn from the light extraction surface of the light extraction member to the light emitting layer, and the viewing angle viewed from this direction is 0 °, and 5 ° up to ± 90 °. The radiant intensity and the light spectrum were measured with a luminance meter (CS-2000 manufactured by Konica Minolta).

FIG. 13 is a diagram showing the results of measuring the radiation intensity at each angle of the organic electroluminescent devices (a) to (d).
From the result of FIG. 13, the ratio (A / B) of the area (A) of the surface on the light emitting layer side of the light extraction member and the area (B) of the surface on the light extraction member side of the light extraction member is 7 or more. The organic electroluminescent device (a) and the organic electroluminescent device (d) are superior in radiation intensity to the organic electroluminescent devices (b) and (c) in which the ratio (A / B) is less than 7. Thus, it was found that the ratio (A / B) is preferably 7 or more in order to further obtain the effect of the light extraction member.

  The organic electroluminescent device of the present invention is excellent in radiation intensity and color, and has little change in chromaticity over a wide viewing angle. Therefore, the organic electroluminescent device is suitable for both a bottom emission type organic electroluminescence device and a top emission type organic electroluminescence device. Used, for example, computers, in-vehicle displays, outdoor displays, household equipment, commercial equipment, home appliances, traffic-related displays, clock displays, calendar displays, luminescent screens, acoustic equipment, etc. It can be suitably used in various fields including the beginning.

DESCRIPTION OF SYMBOLS 1 Hemispherical lens 2 Light emitting layer 3 Light extraction member 4 Perpendicular line 5 Straight line 6 Contact point 7 Straight line 8 Center 9 Straight line 10 Contact point 11 Straight line 12 Glass substrate 13 Water repellent material 14 Resist (negative)
DESCRIPTION OF SYMBOLS 15 Hemisphere 16 Polishing sheet 17 Reflective electrode 18 Organic compound layer 19 Semi-transmissive electrode 20 Shape of light extraction member 51 Anode 52 Hole injection layer 53 Hole transport layer 54 Light emitting layer 55 Electron transport layer 56 Electron injection layer 57 Cathode 58 Light extraction member 61 Glass substrate 62 Cathode 63 Hole injection layer 64 First hole transport layer 65 Second hole transport layer 66 Light emitting layer 67 First electron transport layer 68 Second electron transport layer 69 Electron injection layer 70 Anode 71 Anode 72 Barrier layer 73 Light Extraction Member 100 Organic Electroluminescent Device 101 Organic Electroluminescent Device 200 Organic Electroluminescent Device 201 Organic Electroluminescent Device

Claims (6)

An organic electroluminescent element including at least a light emitting layer between a pair of electrodes, and a light extraction member having a shape of a part of a hemisphere obtained by dividing a sphere in half,
The light emitting layer and the light extraction member have substantially the same refractive index,
The light extraction member is located on an optical path of light emitted from the light emitting layer, and the center of the light emission layer and the center of the light extraction member are in the same position;
The light extraction member is
In a cross section perpendicular to the light emitting layer surface at the center of the light extraction member,
A perpendicular is drawn from the light extraction member to the end of the light emitting layer surface, and the angle at this time is set to 0 °.
From the intersection of the perpendicular and the bottom surface of the light extraction member, draw a straight line forming 60 ° from the perpendicular to the same side as the end of the light emitting layer surface of the light extraction member,
The contact points between the straight line and the arc portion of the light extraction member are connected by a straight line,
An organic electroluminescent device characterized by having a light extraction surface cut out in a horizontal direction with the bottom surface of the light extraction member and parallel to the bottom surface of the hemisphere.   The organic electroluminescent device according to claim 1, wherein the organic electroluminescent element has a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents an emission wavelength). The light extraction member is
In the cross section perpendicular to the light emitting layer surface at the center of the hemisphere, the center of the hemisphere obtained by dividing the sphere in half and the center of the light emitting layer are in the same position.
A perpendicular is drawn from the hemisphere to the end of the light emitting layer surface, and the angle at this time is 0 °.
From the intersection of the perpendicular and the bottom surface of the hemisphere, a straight line forming 35 ° from the perpendicular is drawn on the opposite side of the light emitting layer surface of the hemisphere,
Connecting the straight line and the contact point of the arc of the hemisphere with a straight line,
The top of the sphere cut out horizontally with the bottom of the hemisphere,
The organic electroluminescent device according to claim 1, wherein the organic electroluminescent device is disposed coaxially on a light extraction surface.   The ratio (A / B) of the area (A) of the surface of the light extraction member on the light emitting layer side to the area (B) of the surface of the light emission layer on the light extraction member side is 7 or more. The organic electroluminescent apparatus in any one.   The organic electroluminescence device according to any one of claims 1 to 4, wherein the organic electroluminescence element is a top emission type, and has a sealing layer and a light extraction member in this order on one electrode.   The organic electroluminescence according to any one of claims 1 to 4, wherein the organic electroluminescence device is a bottom emission type, has a substrate, and the shape of each of the substrates on the light emitting layer is the shape of the light extraction member. apparatus.