JP2011018583A - Organic el device and its design method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL device that has high light extraction efficiency and is reduced in the bleeding of images, and a design method of the organic EL device.SOLUTION: The organic EL device at least has an organic EL display part including at least a light-emitting layer between an anode and a cathode, and a nearly-quadrangular pyramid prism that controls an optical path of the light emitted from the light-emitting layer in which the ratio (A/B) of the light extraction efficiency A at the front face brightness when the nearly quadrangular pyramid prism is installed on the light extraction face to the light extraction efficiency B at the front face brightness when the nearly quadrangular pyramid prism is not installed on the light extraction face exceeds 1, and under this light extraction efficiency at the front face brightness, the ratio (h/b) of one edge length b of the nearly-quadrangular pyramid prism to the height h of the nearly quadrangular pyramid prism is 1.2 or smaller.

Description

  The present invention relates to an organic EL device having high light extraction efficiency and less image blur, and a method for designing an organic EL device.

  An organic EL device (organic electroluminescent 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 generally, the refractive index of each layer constituting the display device including the light emitting layer is higher than that of air. For example, in an organic EL device, the refractive index of an organic thin film layer such as a light emitting layer is 1.6 to 2.1. For this reason, the emitted light is easily totally reflected at the interface, and the light extraction efficiency is less than 20%, and most of the light is lost.
For example, an organic EL display unit in a generally known organic EL device includes an organic compound layer disposed between a pair of electrode layers on a substrate. The organic compound layer includes a light emitting layer, and the organic EL device emits light emitted from the light emitting layer from the light extraction surface side. In this case, there is a problem that the light extraction efficiency is low because the total reflection component that is light having a critical angle or more cannot be extracted at the light extraction surface or the interface between the electrode layer and the organic compound layer.

Therefore, in order to improve the light extraction efficiency, a light extraction member such as a prism that controls the optical path of the light emitted from the light emitting layer and emits the light emitted from the light emitting layer from the light extraction surface side is provided. Various organic EL devices arranged on the optical path have been proposed.
For example, Patent Document 1 proposes an electroluminescent device in which square pyramid-shaped microprisms are arranged in a dot matrix corresponding to each pixel on the upper surface of a transparent substrate. According to this proposal, the divergent light emitted from the organic light emitting layer can be refracted in a direction substantially parallel to the normal line of the transparent substrate, and is emitted toward the observer side.
Further, Patent Document 2 proposes an illuminating device including an organic EL element as a planar light emitting element and a prism sheet as an optical element. In this proposal, the prism sheet has a light emitting portion made up of a large number of prism-like convex portions, and a prism having a trapezoidal cross section obtained by cutting out the top of a triangle is used as the convex portion.

Therefore, as a result of the intensive studies by the present inventors in order to solve the above problems, as will be described later, the organic EL device has a light distribution distribution (angle distribution of light) that varies greatly depending on its element design. It was found that the structure of the prism, which is a light extraction member suitable for light extraction, changes depending on the light distribution.
However, in the prior art, this is not taken into consideration at all, and therefore the light extraction efficiency has not been optimized. That is, the optimal prism structure to be combined with the organic EL display unit differs depending on the structure of the organic EL display unit, and the design for optimizing the combination of the structure of the organic EL display unit and the prism has not been performed. As a result, there is a problem that light extraction efficiency with sufficient front luminance cannot be obtained, and image blur occurs when light is guided between the prism and the light emitting layer.

Japanese Patent Laid-Open No. 9-326297 JP 2007-188065 A

  This invention is made | formed in view of this present condition, and makes it a subject to solve the said various problems in the past and to achieve the following objectives. That is, an object of the present invention is to provide an organic EL device that has no image blur, has high extraction efficiency, and can achieve low power consumption, and a method for designing the organic EL device.

Means for solving the problems are as follows. That is,
<1> An organic EL display unit including at least a light emitting layer between an anode and a cathode, and a substantially quadrangular pyramid prism that controls an optical path of light emitted from the light emitting layer,
A ratio between the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface ( A / B) is more than 1 and the light extraction efficiency at the front luminance is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is 1.2 or less.
<2> The organic EL display unit has a primary microcavity structure having an optical length L (λ) of 1λ (where λ represents an emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to <1>, which is 0.7 or less.
<3> The organic EL display unit has a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents an emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to <1>, which is 0.5 or less.
<4> The organic EL display unit has a third-order microcavity structure in which an optical length L (λ) is 3λ (where λ represents an emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to <1>, which is 0.4 or less.
<5> The anode of the organic EL display part is a transparent electrode having a reflectance of 10% or less as viewed from the light emitting layer,
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to <1>, which is 1.2 or less.
<6> The above <1> to <5>, wherein the ratio (d / a) of the distance d between the light emitting layer and the substantially quadrangular pyramid prism and the maximum length a of one side of the light emitting layer is 0.1 or less. The organic EL device according to any one of the above.
<7> A method for designing an organic EL device having at least an organic EL display unit including at least a light emitting layer between an anode and a cathode, and a substantially quadrangular pyramid prism for controlling an optical path of light emitted from the light emitting layer. And
A ratio between the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface ( A / B) is more than 1 and the light extraction efficiency at the front luminance is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is designed so as to satisfy 1.2 or less.

  According to the present invention, it is possible to solve conventional problems, provide an organic EL device that has no image blur, has high extraction efficiency, and consumes low power, and a method for designing the organic EL device.

FIG. 1 is a schematic cross-sectional view showing an example of the organic EL device of the present invention. FIG. 2 is a schematic cross-sectional view showing another example of the organic EL device of the present invention. FIG. 3 is a diagram illustrating an example of a light distribution of an organic EL element (wm = 2). FIG. 4 is a diagram illustrating an example of a light distribution of an organic EL element (sm = 1). FIG. 5 is a diagram illustrating an example of a light distribution of an organic EL element (sm = 2). FIG. 6 is a diagram illustrating an example of a light distribution of an organic EL element (sm = 3). FIG. 7 is a schematic diagram of the organic EL device used in the light extraction efficiency evaluation experiment of Example 1. FIG. 8 is a top view of the organic EL device used in the light extraction efficiency evaluation experiment of Example 1. FIG. FIG. 9 is a graph showing the relationship between the light extraction efficiency at the front luminance of Example 1 and the height of the quadrangular pyramid prism. FIG. 10 is a graph showing the relationship between the light extraction efficiency at the integrated intensity of Example 1 and the height of the quadrangular pyramid prism. FIG. 11 is a schematic diagram of the organic EL device used in the light extraction efficiency evaluation experiment of Example 2. FIG. 12 is a schematic view of an organic EL device used in an experiment for evaluating light extraction efficiency in Example 2. FIG. 13 is a graph showing the relationship between the light extraction efficiency at the front luminance of Example 2 and the height of the quadrangular pyramid prism. FIG. 14 is a graph showing the relationship between the light extraction efficiency at the integrated intensity of Example 2 and the height of the quadrangular pyramid prism. FIG. 15 is a diagram showing a state in which a quadrangular pyramid prism is arranged for each pixel in the RGB three pixels. FIG. 16 is a diagram illustrating a state in which a quadrangular pyramid prism is arranged with RGB3 pixels as a unit. FIG. 17 is a diagram illustrating a state where a large number of small prisms are arranged in one pixel.

(Organic EL device and organic EL device design method)
The organic EL device of the present invention includes at least an organic EL display unit and a substantially quadrangular pyramid prism provided on a light extraction surface, and includes a substrate, a barrier layer, and other members as necessary.
The organic EL device design method of the present invention is a method of designing the organic EL device of the present invention,
A ratio between the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface ( A / B) is more than 1 and the light extraction efficiency at the front luminance is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is designed to satisfy 1.2 or less.
Hereinafter, the organic EL device and the design method of the organic EL device of the present invention will be described in detail.

  In the present invention, first, the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface, and the front luminance when the substantially square pyramid prism is not provided on the light extraction surface. The ratio (A / B) with respect to the light extraction efficiency B is more than 1.

When the ratio (A / B) exceeds 1, the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface is the same as that when the substantially square pyramid prism is not provided on the light extraction surface. This means that the light extraction efficiency B at the front luminance is higher than the light extraction efficiency B. By providing a substantially quadrangular pyramid prism on the light extraction surface, the light extraction efficiency at the front luminance is improved and the brightness when viewed from the front is improved. improves.
Here, the front luminance rather than the integrated intensity is adopted for the light extraction efficiency. Considering application to the organic EL display, the power consumption is defined as the power to obtain a constant front luminance. This is because the front luminance is more important than the integrated intensity from the viewpoint of an index.
The ratio (A / B) is not particularly limited as long as it exceeds 1, and can be appropriately selected according to the purpose, but is preferably 1.5 or more, and more preferably 2.0 or more. When the ratio (A / B) is 1 or less, there is no effect of providing a substantially quadrangular pyramid prism as a light extraction member, and the object of the present invention may not be achieved.
Here, the light extraction efficiency at the front luminance is the front luminance of the organic EL device in which the substantially quadrangular pyramid prism is mounted on the light extraction surface, and the front luminance of the organic EL device in which the approximately square pyramid prism is not mounted on the light extraction surface. It can be obtained from the divided value. The front luminance can be measured by, for example, a spectral radiance meter (SR-3, manufactured by Topcon).

In the present invention, secondly, in the light extraction efficiency at the front luminance, the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is 1. 2 or less.
Here, the length b of one side of the base of the substantially quadrangular pyramid prism usually means the length of one side on the bottom surface of the substantially quadrangular pyramid prism, and may be appropriately selected depending on the shape of the quadrangular pyramid. For example, when the length of one side of the bottom surface is equal (for example, the bottom surface is square), any one side may be used, but when the length of one side of the bottom surface is different (for example, the bottom surface is rectangular) Adopt the longest side.
The height h of the substantially quadrangular pyramid prism means the height from the light extraction surface (for example, the glass substrate surface) on which the substantially quadrangular pyramid prism is provided.

In the light extraction efficiency at the front luminance, the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is 1.2 or less; 7 or less is preferable and 0.5 or less is more preferable. The lower limit is preferably 0.2 or more.
When the ratio (h / b) exceeds 1.2, the front luminance may be lower than when no prism is attached.

  The light extraction efficiency at the integrated intensity is not particularly limited and can be appropriately selected depending on the structure of the organic EL display unit (organic EL element). However, a substantially quadrangular pyramid prism is provided on the light extraction surface. The ratio (C / D) of the light extraction efficiency C at the integrated intensity to the light extraction efficiency D at the integrated intensity when the substantially quadrangular pyramid prism is not provided on the light extraction surface exceeds 1, and the approximately four The ratio (h / b) of the light extraction efficiency at the integrated intensity between the length b of one side of the pyramid prism and the height h of the substantially quadrangular pyramid prism is preferably 2.4 or less. .4 or less is more preferable.

  The ratio (C / D) exceeding 1 means that the light extraction efficiency at the integrated intensity is improved by attaching a substantially square pyramid prism. Even if the light extraction efficiency at the front luminance is high, if the light extraction efficiency at the integrated intensity is low, the brightness when viewed from an oblique direction may not be sufficient.

  Here, the light extraction efficiency at the integrated intensity is the integrated intensity of the organic EL device in which the substantially quadrangular pyramid prism is mounted on the light extraction surface, and the integrated intensity of the organic EL device in which the approximately quadrangular pyramid prism is not mounted on the light extraction surface. It can be obtained from the divided value. The integrated intensity can be measured, for example, with a spectral radiance meter (SR-3, manufactured by Topcon).

  The ratio (h / b) of the light extraction efficiency at the front luminance and the integrated intensity varies depending on the structure of the organic EL display unit (organic EL element), the height of the substantially quadrangular pyramid prism, and the like. The light extraction efficiency can be optimized by combining a substantially quadrangular pyramid prism that matches the structure of the organic EL display unit.

  Here, there is no restriction | limiting in particular as a structure of the said organic EL display part, 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 EL display part, (2) Optical length of microcavity structure, (3) Bottom emission type or top emission type.

As the electrode (anode) on the light emission side of the organic EL display unit (1), in the bottom emission type, a transparent electrode (for example, ITO) having a reflectance as viewed from the light emitting layer of 10% or less, 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 EL display unit. 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.

<First Embodiment>
In the first embodiment, the organic EL display unit has a primary microcavity structure with an optical length L (λ) of 1λ (where λ represents an emission wavelength), and is a bottom emission type and a top emission type. Any type.
In the first embodiment, the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface, and the light extraction at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface. In the light extraction efficiency at the front luminance with a ratio (A / B) to the efficiency B exceeding 1, the length b of one side of the substantially square pyramid prism and the height h of the substantially square pyramid prism The ratio (h / b) is preferably 0.7 or less, and more preferably 0.4 or less. The lower limit is preferably 0.2 or more.
Further, the ratio of the light extraction efficiency C at the integrated intensity when the substantially quadrangular pyramid prism is provided on the light extraction surface and the light extraction efficiency D at the integral intensity when the approximate square pyramid prism is not provided on the light extraction surface ( C / D) exceeds 1, and the light extraction efficiency at the integrated intensity is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is preferably 0.45 or less.

<Second Embodiment>
In the second embodiment, the organic EL display unit has a secondary microcavity structure with an optical length L (λ) of 2λ (where λ represents an emission wavelength), and is a bottom emission type and a top emission type. Any type.
In the second embodiment, the light extraction efficiency A at the front luminance when the substantially quadrangular pyramid prism is provided on the light extraction surface, and the light extraction at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface. In the light extraction efficiency at the front luminance with a ratio (A / B) to the efficiency B exceeding 1, the length b of one side of the substantially square pyramid prism and the height h of the substantially square pyramid prism The ratio (h / b) is preferably 0.5 or less. The lower limit is preferably 0.2 or more.
Further, the ratio of the light extraction efficiency C at the integrated intensity when the substantially quadrangular pyramid prism is provided on the light extraction surface and the light extraction efficiency D at the integral intensity when the approximate square pyramid prism is not provided on the light extraction surface ( C / D) exceeds 1, and the light extraction efficiency at the integrated intensity is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is preferably 1.2 or less, and more preferably 0.35 or less.

<Third Embodiment>
In the third embodiment, the organic EL display unit has a third-order microcavity structure with an optical length L (λ) of 3λ (where λ represents an emission wavelength), and is a bottom emission type and a top emission type. Any type.
In the third embodiment, the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface, and the light extraction at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface. In the light extraction efficiency at the front luminance with a ratio (A / B) to the efficiency B exceeding 1, the length b of one side of the substantially square pyramid prism and the height h of the substantially square pyramid prism The ratio (h / b) is preferably 0.4 or less. The lower limit is preferably 0.2 or more.
In the third embodiment, the light extraction efficiency at the integrated intensity is not particularly limited and can be appropriately selected according to the purpose.

<Fourth Embodiment>
In the fourth embodiment, the anode of the organic EL display unit is a transparent electrode (for example, ITO) having a reflectance of 10% or less when viewed from the light emitting layer, and is a bottom emission type.
In the fourth embodiment, the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface, and the light extraction at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface. In the light extraction efficiency at the front luminance with a ratio (A / B) to the efficiency B exceeding 1, the length b of one side of the substantially square pyramid prism and the height h of the substantially square pyramid prism The ratio (h / b) is preferably 1.2 or less, and more preferably 0.5 or less. The lower limit is preferably 0.2 or more.
In the fourth embodiment, the light extraction efficiency at the integrated intensity is not particularly limited and can be appropriately selected according to the purpose.

In the present invention, the ratio (d / a) between the distance d between the light emitting layer and the substantially quadrangular pyramid prism and the maximum length a of one side of the light emitting layer is preferably 0.1 or less. .05 or less is more preferable. When the ratio (d / a) exceeds 0.1, image blur may occur.
Here, the maximum length a of one side of the light emitting layer varies depending on the shape of the light emitting layer and can be appropriately selected. For example, when the length of one side is equal (for example, a square), Although it may be a side, when the length of one side is different (for example, a rectangle), the longest side is adopted.

<Organic EL display>
The organic EL display unit (organic EL element) has at least a light emitting layer between an anode and a 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 EL display unit 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 Layer and inorganic layer laminated alternately (Japanese Patent Laid-Open No. 2007-30387, US Pat. No. 6,436,645, Affinito et al., Thin Solid Films 1996, pages 290-291), organic layer and inorganic layer continuously A laminate (US Patent Application Publication No. 2004-46497) and the like can be mentioned.

  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.

<Substantially square pyramid prism>
The substantially quadrangular pyramid prism has a function of controlling an optical path of light emitted from the light emitting layer provided on the light extraction surface.
Examples of the substantially quadrangular pyramid prism include those having a substantially square bottom to a substantially rectangular bottom. In addition, the substantially quadrangular pyramid prism includes those having a triangular apex having a curved shape and those having a trapezoidal cross section obtained by cutting the apex of the triangle. The prism shape is not particularly limited as long as the effects of the present invention can be achieved, and may be a triangular prism, a cone, a hexagonal pyramid, an octagonal pyramid, or the like other than a quadrangular pyramid.
The substantially quadrangular pyramid prisms are not limited to being arranged one for each pixel, and a plurality of them may be arranged. Further, a large number of small prisms may be arranged in one pixel.
Examples of the light extraction surface include a glass substrate in the bottom emission type. In the top emission type, for example, a barrier layer and the like can be mentioned.

The substantially quadrangular pyramid prism is not particularly limited in its arrangement, size, material, and the like, and can be appropriately selected according to the purpose. Examples of the prism arrangement include a square lattice, a honeycomb, and a dot. Examples include matrix.
Examples of the material of the prism include transparent resin, glass, transparent crystal, and transparent ceramic.
The length b of one side of the bottom surface of the substantially quadrangular pyramid prism is not particularly limited and may be appropriately selected according to the purpose. The length is preferably 5 μm or more, more preferably 10 μm to 200 μm. If the length b of one side of the bottom surface is less than 5 μm, the influence of diffraction may occur and the light extraction efficiency may be lowered.

There is no restriction | limiting in particular as a preparation method of the said substantially square pyramid prism, 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 as to form a substantially quadrangular pyramid prism, and then the transparent mold is pressed onto the organic EL element. Then, after irradiating with UV light, a substantially quadrangular pyramid prism can be formed on the organic EL element by releasing the mold.

-Barrier 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. 1 is a schematic sectional view showing a bottom emission type organic EL device which is an example of the organic EL device of the present invention. FIG. 2 is a schematic cross-sectional view showing a top emission type organic EL device which is an example of the organic EL device of the present invention.

A bottom emission type organic EL device 100 shown in FIG. 1 includes an organic EL display unit 101 (anode 2, hole injection layer 3, hole transport layer 4, light emitting layer 5, electron transport layer 6, electron injection layer on a glass substrate 1. 7 and a cathode 8), and a quadrangular pyramid prism 9 is formed on a glass substrate 1 as a light extraction surface.
A top emission type organic EL device 200 shown in FIG. 2 has an organic EL display unit 201 (cathode 8, hole injection layer 3, hole transport layer 4, light emitting layer 5, electron transport layer 6, electron injection layer on a glass substrate 1. 7, an anode 2), a gas barrier layer 10 is formed on the anode 2, and a quadrangular pyramid prism 9 is formed on the gas barrier layer 10 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 EL device. In the case of the bottom emission type organic EL device 100 shown in FIG. 1, as indicated by an arrow, a downward direction is shown in parallel with the drawing as viewed from the light emitting layer 5. In the case of the top emission type organic EL device 200 shown in FIG. 2, as indicated by an arrow, the direction from the light emitting layer 5 toward the upper side in parallel with the drawing is shown.

  The organic EL device of the present invention may be configured as a device capable of displaying in full color. As a method for making the organic EL device of the present invention of a full color type, for example, as described in “Monthly Display”, September 2000, pages 33 to 37, three primary colors (blue (B) , Green (G), red (R), each of which emits light corresponding to a three-color light emission method in which a layer structure for emitting light is arranged on a substrate, and white light emitted by a layer structure for white light emission is divided into three primary colors through a color filter. And a color conversion method in which blue light emission by a layer structure for blue light emission is converted into red (R) and green (G) through a fluorescent dye layer 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 EL device of the present invention includes, for example, a computer, a vehicle-mounted display, a field display, a household device, a business device, a home appliance, a traffic display, a clock display, a calendar display, and a luminescent screen. It can be suitably used in various fields including acoustic equipment.

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

Example 1
The following four types of organic EL elements (1) to (4) of the bottom emission type were produced as follows.

<Preparation of organic EL element (1) (wm = 2); when the anode is a transparent electrode (ITO)>
As a glass substrate, S-TIH6 (made by OHARA) having a thickness of 0.2 mm and a refractive index of 1.8 was used.
Next, ITO as an anode was formed on the glass substrate by vacuum deposition so that the thickness was 100 nm. The reflectance of the produced ITO film as seen from the light emitting layer was 2%, and the transmittance was 97%.
Next, on the ITO film, 2-TNATA [4,4 ′, 4 ″ -tris (2-naphthylphenylamino) triphenylamine] and MnO ₃ are used as a hole injection layer in a ratio of 7: 3 and 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 was formed by vacuum deposition so as to have 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, a hole transport material A represented by the following structural formula as a third hole transport layer was formed on the second hole transport layer by vacuum deposition so as to have a thickness of 3 nm.

Next, on the third hole transport layer, the light-emitting layer is formed using CBP (4,4′-dicarbazole-biphenyl) as a host material, and the 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 20 nm at a ratio of 15.

Next, BAlq (Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate) is formed as a first electron transporting layer on the light emitting layer by vacuum deposition so as to have a thickness of 39 nm. did.
Next, on the first electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin) as a second electron transport layer is vacuumed so that the thickness becomes 1 nm. It was formed by vapor deposition.
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 nm.
Next, aluminum (Al) as a cathode was formed on the electron injection layer by vacuum deposition so as to have a thickness of 100 nm.
Thus, an organic EL element (1) was produced.

<Preparation of organic EL element (2) (sm = 1); optical length is primary microcavity structure>
The organic EL element (1) was manufactured except that an anode 20 nm thick Ag film was formed instead of the 100 nm thick ITO film as the anode, and the thickness of the first hole transport layer was changed from 141 nm to 11 nm. The organic EL element (2) was produced in the same manner as in the production of (1). The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
The obtained organic EL element (2) had a primary microcavity structure having an optical length L (λ) of 1λ (where λ represents a light emission wavelength).

<Preparation of Organic EL Element (3) (sm = 2); When Optical Length is Secondary Microcavity Structure>
In the production of the organic EL element (1), the organic EL element (3) was produced in the same manner as the production of the organic EL element (1) except that an Ag film having a thickness of 20 nm was formed as an anode instead of the ITO film having a thickness of 100 nm. Was made. The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
The obtained organic EL device (3) had a secondary microcavity structure with an optical length L (λ) of 2λ (where λ represents a light emission wavelength).

<Preparation of organic EL element (4) (sm = 3); when optical length is a tertiary microcavity structure>
The organic EL element (1) was prepared by changing the thickness of the first hole transport layer from 141 nm to 271 nm in place of the 100 nm thick ITO film instead of the 100 nm thick ITO film. The organic EL element (4) was produced in the same manner as in the production of (1). The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
The obtained organic EL element (4) had a tertiary microcavity structure with an optical length L (λ) of 3λ (where λ represents a light emission wavelength).

  Each of the produced organic EL elements was optimized for light emission of green (about 530 nm), and the maximum length a of one side of the light emitting portion (light emitting layer) of each organic EL element was 2 mm.

Next, for each of the produced organic EL devices, a cylinder lens having a sufficiently large diameter (radius 10 mm) and a refractive index of 1.8 is used as a matching oil (refractive index = 1.8) on a glass substrate as a light extraction surface. ). About each organic EL element, light distribution was measured as follows. This evaluation makes it possible to know the angular distribution of light in the glass.
The result of the light distribution of the organic EL element (1) (wm = 2) is shown in FIG. 3, the result of the light distribution of the organic EL element (2) (sm = 1) is shown in FIG. 4, and the result of the organic EL element (3) (sm = 2) shows the result of the light distribution, and FIG. 6 shows the result of the light distribution of the organic EL element (4) (sm = 3).
<Measurement method of light distribution>
A silicon detector was attached to the goniometer, each organic EL element was caused to emit light, and the relationship between the angle of the goniometer and the voltage signal corresponding to the light intensity from the detector was measured to obtain the light distribution.

From the results of FIGS. 3 to 6, it was found that the light distribution in the glass in each organic EL element (angle distribution of light) varies greatly depending on the structure of the organic EL element. That is, in the organic EL element (1) (wm = 2) of FIG. 3 and the organic EL element (3) (sm = 2) of FIG. 5, the anode is a transparent electrode (ITO) or a semi-transmissive electrode (Ag electrode). However, as shown in FIGS. 3 and 5, it was found that the light distribution in the glass is greatly different.
Also, the organic EL element (2) (sm = 1) in FIG. 4, the organic EL element (3) (sm = 2) in FIG. 5, and the organic EL element (4) (sm = 3) in FIG. The thickness of the transport layer is different, and the optical length of the microcavity structure is different. 4, 5, and 6, it was found that the light distribution (the angular distribution of light) is different when the optical length of the microcavity structure is different from the first order, the second order, and the third order.

  Here, when the light extraction surface of each organic EL element is not equipped with a quadrangular pyramid prism as a light extraction member, the total reflection angle at the interface between glass and air is ± 33 °, which is an angle larger than this angle. No light is emitted into the air.

Next, in each organic EL element, a case where a quadrangular pyramid prism as a light extraction member is mounted will be considered.
It is difficult to predict the quantitative behavior of the light extraction efficiency with respect to the quadrangular pyramid prism in consideration of the light distribution of the actual organic EL element, and the evaluation experiment of the light extraction efficiency was performed as follows.

<Evaluation experiment of light extraction efficiency>
As shown in FIG. 7 and FIG. 8, a quadrangular pyramid prism 22 having a refractive index of 1.8 produced by cutting is produced on a glass substrate 23 serving as a light extraction surface of the organic EL element by five-face polishing. Each organic EL device was fabricated by attaching with an adhesive in which refractive index nanoparticles (TiO ₂ ) were dispersed. Then, the length b of one side of the quadrangular pyramid prism 22 was set to 2 mm, and the height h of the quadrangular pyramid prism was changed from 0 mm to 3 mm.
In each organic EL device, the ratio (d / a) between the distance d between the light emitting layer and the quadrangular pyramid prism and the maximum length a of one side of the light emitting layer was 0.1.

About each produced organic EL apparatus, the light extraction efficiency was measured as follows. The light extraction efficiency was measured for both integrated intensity and front luminance. The results are shown in FIG. 9 (front luminance) and FIG. 10 (integrated intensity).
<Light extraction efficiency>
A value obtained by dividing the front luminance of the organic EL element equipped with the quadrangular pyramid prism by the front luminance of the organic EL element not equipped with the quadrangular pyramid prism was defined as the light extraction efficiency at the front luminance.
A value obtained by dividing the integral intensity of the organic EL element equipped with the quadrangular pyramid prism by the integral intensity of the organic EL element not equipped with the quadrangular pyramid prism was defined as the light extraction efficiency at the integral intensity.
The integrated intensity and front luminance were measured with a spectral radiance meter (SR-3, manufactured by Topcon Corporation).

  From the results of FIGS. 9 and 10, it was found that the front luminance and the integrated intensity of the light extraction efficiency vary depending on the height h and ratio (h / b) of the quadrangular pyramid prism, and differ depending on the configuration of the organic EL element. . Hereinafter, each organic EL element will be described.

<Organic EL element (1) (wm = 2): When the anode of an organic EL element is a transparent electrode (ITO)>
As shown in FIG. 9, in the organic EL element (1), the front luminance of the light extraction efficiency increases rapidly until the height h of the quadrangular pyramid prism reaches 0.5 mm, and then decreases rapidly, It was found that the reduction rate was larger than that of the EL elements (2) to (4).
Therefore, in the organic EL element (1), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) with B exceeded 1 was that the ratio (h / b) for light extraction efficiency at the front luminance was 1.2 or less.
Further, as shown in FIG. 10, it was found that the organic EL element (1) is not affected by the height h and the ratio (h / b) of the quadrangular pyramid prism with respect to the integrated intensity of the light extraction efficiency.

<Organic EL element (2) (sm = 1): When optical length is a primary microcavity structure>
As shown in FIG. 9, in the organic EL element (2), the front luminance of the light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm and then decreased.
Therefore, in the organic EL element (2), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) for light extraction efficiency at the front luminance was 0.7 or less.
Further, as shown in FIG. 10, the organic EL element (2) was found that the integrated intensity of the light extraction efficiency increased until the height h of the quadrangular pyramid prism increased to 0.3 mm and then decreased. .
Therefore, in the organic EL element (2), the light extraction efficiency C at the integrated intensity when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the integral intensity when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (C / D) with D exceeded 1 when the ratio (h / b) of the integrated intensity of light extraction efficiency was 0.45 or less.

<Organic EL element (3) (sm = 2): When optical length is a secondary microcavity structure>
As shown in FIG. 9, in the organic EL element (3), the front luminance of light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm and then decreased.
Accordingly, in the organic EL element (3), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) of the front luminance of light extraction efficiency was 0.5 or less.
Further, as shown in FIG. 10, in the organic EL element (3), the integrated intensity of the light extraction efficiency decreases after the height h of the quadrangular pyramid prism increases to 0.3 mm, and decreases after increasing again. I understood that.
Therefore, in the organic EL element (3), the light extraction efficiency C with the integrated intensity when the quadrangular pyramid prism is provided on the light extraction surface and the light extraction efficiency with the integrated intensity when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (C / D) with D exceeded 1 when the ratio (h / b) of the integrated intensity of light extraction efficiency was 1.2 or less.

<Organic EL element (4) (sm = 3): When optical length is a tertiary microcavity structure>
As shown in FIG. 9, in the organic EL element (4), the front luminance of the light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm and then decreased.
Accordingly, in the organic EL element (4), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) of the front luminance of light extraction efficiency was 0.4 or less.
Further, as shown in FIG. 10, the organic EL element (4) was found not to be affected by the height h and the ratio (h / b) of the quadrangular pyramid prism with respect to the integrated intensity of the light extraction efficiency.

(Example 2)
Three types of top emission type organic EL elements (5) to (7) were respectively produced as follows.

<Preparation of organic EL element (5) (sm = 1); When optical length is primary microcavity structure>
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 MnO ₃ are in a ratio of 7: 3 and the thickness is 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 was formed by vacuum deposition so as to have a thickness of 11 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, a hole transport material A represented by the following structural formula as a third hole transport layer material was formed on the second hole transport layer by vacuum deposition so as to have a thickness of 3 nm.

Next, on the third hole transport layer, the light-emitting layer is formed using CBP (4,4′-dicarbazole-biphenyl) as a host material, and the 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 20 nm at a ratio of 15.

Next, BAlq (Aluminum (III) bis (2-methyl-8-quinolinato) -4-phenylphenolate) is formed as a first electron transporting layer on the light emitting layer by vacuum deposition so as to have a thickness of 39 nm. did.
Next, on the first electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthrolin) as a second electron transport layer is vacuumed so that the thickness becomes 1 nm. It was formed by vapor deposition.
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 nm.
Next, Ag was formed as an anode on the electron injection layer by vacuum deposition so as to have a thickness of 20 nm. The reflectance of the manufactured Ag film as viewed from the light emitting layer was 47%, and the transmittance was 45%.
Thus, an organic EL element (5) was produced.
The obtained organic EL element (5) had a primary microcavity structure with an optical length L (λ) of 1λ (where λ represents a light emission wavelength).

<Preparation of Organic EL Element (6) (sm = 2); When Optical Length is Secondary Microcavity Structure>
In the production of the organic EL element (5), the organic EL element (6) was produced in the same manner as the production of the organic EL element (5) except that the thickness of the first hole transport layer was changed from 11 nm to 141 nm. .
The obtained organic EL element (6) had a secondary microcavity structure with an optical length L (λ) of 2λ (where λ represents an emission wavelength).

<Preparation of organic EL element (7) (sm = 3); When optical length is tertiary microcavity structure>
In the production of the organic EL element (5), the organic EL element (7) was produced in the same manner as in the production of the organic EL element (5) except that the thickness of the first hole transport layer was changed from 11 nm to 271 nm. .
The obtained organic EL element (7) had a tertiary microcavity structure with an optical length L (λ) of 3λ (where λ represents a light emission wavelength).

  Each of the produced organic EL elements was optimized for light emission of green (about 530 nm), and one side of the light emitting portion (light emitting layer) of each organic EL element had a maximum length a of 2 mm.

  Next, the light distribution was measured for each of the produced organic EL elements in the same manner as in Example 1. By this evaluation, the light distribution in the glass (angle distribution of light) can be known. FIG. 4 shows the result of the light distribution of the organic EL element (5) (sm = 1), FIG. 5 shows the result of the light distribution of the organic EL element (6) (sm = 2), and the organic EL element (7) ( The result of the light distribution of sm = 3) is shown in FIG.

From the results of FIGS. 4 to 6, it was found that the light distribution in the glass (angle distribution of light) in each organic EL element varies greatly depending on the structure of the organic EL element.
That is, the organic EL element (5) of FIG. 4, the organic EL element (6) of FIG. 5, and the organic EL element (7) of FIG. The length is different. 4, 5, and 6, it was found that the light distribution (the angular distribution of light) is different when the optical length of the microcavity structure is different from the first order, the second order, and the third order.

Next, about each organic EL element, light extraction efficiency was evaluated as follows.
<Evaluation experiment of light extraction efficiency>
As shown in FIG. 11 and FIG. 12, a high-refractive-index inorganic fine particle (TiO ₂ ) is dispersed on a light extraction surface of an organic EL element with a quadrangular pyramid prism 22 having a refractive index of 1.8 produced by cutting. The organic EL device was produced by pasting with resin. Then, the length b of one side of the quadrangular pyramid prism was set to 2 mm, and the height h of the quadrangular pyramid prism was changed from 0 mm to 3 mm.
In each organic EL device, the ratio (d / a) between the distance d between the light emitting layer and the quadrangular pyramid prism and the maximum length a of one side of the light emitting layer was 0.1.

  About each produced organic EL apparatus, it carried out similarly to Example 1, and measured the light extraction efficiency. The light extraction efficiency was measured for both integrated intensity and front luminance. The results are shown in FIG. 13 (front luminance) and FIG. 14 (integrated intensity).

  From the results of FIGS. 13 and 14, it was found that the front luminance and the integrated intensity of the light extraction efficiency vary depending on the height h and the ratio (h / b) of the quadrangular pyramid prism, and differ depending on the configuration of the organic EL element. . Hereinafter, each organic EL element will be described.

<Organic EL element (5) (sm = 1): When optical length is a primary microcavity structure>
As shown in FIG. 13, in the organic EL element (5), the front luminance of the light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm and then decreased.
Therefore, in the organic EL element (5), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) for light extraction efficiency at the front luminance was 0.7 or less.
Further, as shown in FIG. 14, the organic EL element (5) was found that the integrated intensity of the light extraction efficiency increased until the height h of the quadrangular pyramid prism increased to 0.3 mm, and then decreased. .
Accordingly, in the organic EL element (5), the light extraction efficiency C with the integrated intensity when the quadrangular pyramid prism is provided on the light extraction surface and the light extraction efficiency with the integral intensity when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (C / D) with D exceeded 1 when the ratio (h / b) of the integrated intensity of light extraction efficiency was 0.45 or less.

<Organic EL element (6) (sm = 2): When optical length is a secondary microcavity structure>
As shown in FIG. 13, in the organic EL element (6), the front luminance of the light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm, and then decreased.
Therefore, in the organic EL element (6), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) of the front luminance of light extraction efficiency was 0.5 or less.
In the organic EL element (6), as shown in FIG. 14, the integrated intensity of the light extraction efficiency decreases after the height h of the quadrangular pyramid prism increases to 0.3 mm, and decreases after increasing again. I understood that.
Therefore, in the organic EL element (6), the light extraction efficiency C with the integrated intensity when the quadrangular pyramid prism is provided on the light extraction surface and the light extraction efficiency with the integrated intensity when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (C / D) with D exceeded 1 when the ratio (h / b) of the integrated intensity of light extraction efficiency was 1.2 or less.

<Organic EL element (7) (sm = 3): When optical length is a tertiary microcavity structure>
As shown in FIG. 13, in the organic EL element (7), the front luminance of the light extraction efficiency was found to increase until the height h of the quadrangular pyramid prism increased to 0.5 mm and then decreased.
Accordingly, in the organic EL element (7), the light extraction efficiency A at the front luminance when the quadrangular pyramid prism is provided on the light extraction surface, and the light extraction efficiency at the front luminance when the square pyramid prism is not provided on the light extraction surface. It was found that the ratio (A / B) to B exceeded 1 was that the ratio (h / b) of the front luminance of light extraction efficiency was 0.4 or less.
Further, as shown in FIG. 14, the organic EL element (7) was found not to be affected by the height h and the ratio (h / b) of the quadrangular pyramid prism with respect to the integrated intensity of the light extraction efficiency.

  From the results of Examples 1 and 2 described above, the optimum height h of the quadrangular pyramid prism to be combined differs depending on the configuration of the organic EL element, and the combination of the configuration of the organic EL element and the quadrangular pyramid prism is not optimized. It was found that there is a region where sufficient light extraction efficiency cannot be obtained.

The results of Example 1 and Example 2 described above were performed for one pixel of green (about 530 nm), but similar results were obtained for blue (about 470 nm) and red (about 630 nm).
That is, when a device having three RGB pixels of red (R), green (G), and blue (B) is manufactured and a quadrangular pyramid prism is arranged for the three RGB pixels, as shown in FIG. Each pixel may be surrounded by a quadrangular pyramid prism. Alternatively, as shown in FIG. 16, three RGB pixels may be surrounded by a quadrangular pyramid prism as a unit. The number of quadrangular pyramid prisms is not limited to one per pixel, and a plurality of quadrangular pyramid prisms may be arranged. As shown in FIG. 17, a large number of small quadrangular pyramid prisms 24 can be arranged in one pixel G.
Moreover, there is no restriction | limiting in particular about the shape of a pixel, According to the objective, it can change suitably, For example, a square pixel, a rectangular pixel, a circular pixel, a triangular pixel, etc. are mentioned.
In Examples 1 and 2, an organic EL element having a maximum length a of 2 mm on one side of the light emitting portion (light emitting layer) was fabricated and evaluated. However, the size of the prism (length of one side) was evaluated. If the ratio (a / b) between b) and the maximum length a of one side of the light emitting portion (light emitting layer) is the same, the optical properties are equivalent.
Actually, an organic EL device having a maximum length a of 2 μm on one side of the light emitting portion (light emitting layer) was prepared and evaluated in the same manner. At this time, an experiment was conducted using a glass substrate having a thickness (d) of 20 μm. As a result, the same optical properties as in the case where one side was 2 mm were obtained.

  Since the organic EL device of the present invention has high light extraction efficiency and little image blur, it can be suitably used for both bottom emission type organic EL display devices and top emission type organic EL display devices. In various fields including in-vehicle displays, outdoor displays, household equipment, commercial equipment, household appliances, traffic-related displays, clock displays, calendar displays, luminescent screens, acoustic equipment, etc. It can be preferably used.

DESCRIPTION OF SYMBOLS 1 Glass substrate 2 Anode 3 Hole injection layer 4 Hole transport layer 5 Light emitting layer 6 Electron transport layer 7 Electron injection layer 8 Cathode 9 Square pyramid prism 10 Barrier layer 21 Pixel 22 Square pyramid prism 23 Glass substrate 24 Small square pyramid prism 100 Organic EL Device 101 Organic EL element (Organic EL display unit)
200 Organic EL Device 201 Organic EL Element (Organic EL Display Unit)

Claims (7)

An organic EL display unit including at least a light emitting layer between an anode and a cathode, and a substantially quadrangular pyramid prism for controlling an optical path of light emitted from the light emitting layer,
A ratio between the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface ( A / B) is more than 1 and the light extraction efficiency at the front luminance is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is 1.2 or less. The organic EL display unit has a primary microcavity structure with an optical length L (λ) of 1λ (where λ represents an emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to claim 1, which is 0.7 or less. The organic EL display unit has a secondary microcavity structure having an optical length L (λ) of 2λ (where λ represents a light emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to claim 1, which is 0.5 or less. The organic EL display unit has a third-order microcavity structure in which an optical length L (λ) is 3λ (where λ represents an emission wavelength),
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to claim 1, which is 0.4 or less. The anode of the organic EL display unit is a transparent electrode having a reflectance of 10% or less as viewed from the light emitting layer,
Ratio of light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface (A / B) is greater than 1 and the light extraction efficiency at the front luminance is such that the ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism is The organic EL device according to claim 1, which is 1.2 or less.   The ratio (d / a) between the distance d between the light emitting layer and the substantially square pyramid prism and the maximum length a of one side of the light emitting layer is 0.1 or less. Organic EL device. An organic EL device design method comprising at least an organic EL display unit including at least a light emitting layer between an anode and a cathode, and a substantially quadrangular pyramid prism for controlling an optical path of light emitted from the light emitting layer,
A ratio between the light extraction efficiency A at the front luminance when the substantially square pyramid prism is provided on the light extraction surface and the light extraction efficiency B at the front luminance when the substantially square pyramid prism is not provided on the light extraction surface ( A / B) is more than 1 and the light extraction efficiency at the front luminance is a ratio (h / b) between the length b of one side of the substantially quadrangular pyramid prism and the height h of the substantially quadrangular pyramid prism. ) Is designed so as to satisfy 1.2 or less.