JP2010198907A - Organic electroluminescent display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an organic electroluminescent display device which can control radiation distribution of light with high light extraction efficiency, is free from blurring of image, and is easy to manufacture with shallow formation of via. <P>SOLUTION: The organic electroluminescent display device includes an optical path-changing means provided between a substrate and an organic electroluminescent element including a substrate and a light-emitting layer, the means changing into the light-emitting layer side the optical path of light emitted from the light-emitting layer toward the substrate. The optical path changing means has a plurality of discontinous reflecting surfaces so that the light can be focused toward a light extraction area. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a top emission type organic electroluminescent display device which has high light extraction efficiency and is easy to manufacture.

  An organic electroluminescence display device (organic electroluminescence display device) is a self-luminous display device, and is used for displays and illumination. Organic electroluminescent displays have 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 made lighter and thinner. On the other hand, in addition to the advantages of lightening and thinning the organic electroluminescent illumination, there is a possibility that it is possible to realize illumination having a shape that could not be realized by using a flexible substrate.

  The organic light emitting display device has excellent characteristics as described above, 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 light emitting display 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 its light extraction efficiency is less than 20%, and most of the light is lost.

As a technique for improving the light extraction efficiency, in a top emission type organic electroluminescence display device, the light emitted from the light emitting layer is omitted in the cross-sectional view disposed between the light emitting layer and the substrate (circuit). A method is disclosed in which the light is reflected by a sinusoidal reflective layer and taken out from the light emitting layer side (see Patent Document 1).
However, the substantially sinusoidal reflecting layer functions as a diffraction grating because of its shape, and the light extraction efficiency is diffracted as ± 1st-order diffracted light in the direction opposite to the light extraction direction. There is a problem that is not enough.
That is, when the + 1st order direction is the front direction of the display, light that is not extracted is generated in the -1st order direction when the direction is parallel to the substrate and the back side.

Also, in a bottom emission type organic electroluminescence display device, light emitted from the light emitting layer is concavely reflected by a cathode formed in a concave shape on the substrate (circuit), and light is emitted from the anode side arranged on the substrate. A method of improving the directivity of extracted light (see, for example, Patent Document 2) is disclosed.
However, a bottom emission type organic light emitting display device has a problem that light extraction efficiency is not always sufficient because light propagates inside a substrate such as glass.

In this regard, if the concave reflecting member is applied to a top emission type organic light emitting display device, for example, as shown in FIG. 6, the concave reflecting member 5 ′ is bulky, so that the transistor 4 and the electrode (anode 7). joining the door, the electrode output voltage of the transistor 4 (e.g., the anode 7) it is necessary to deeply form the via 14 to be transmitted (see T ₁ of the in FIG. 6), there is a problem that the manufacturing becomes difficult.

JP 2006-107745 A Japanese Patent Laid-Open No. 2001-217078

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, it is an object of the present invention to provide an organic light emitting display device that has high light extraction efficiency, can control light radiation distribution, has no image blur, has a shallow via formation, and is easy to manufacture. .

Means for solving the above problems are as follows. That is,
<1> An optical path changing unit capable of changing an optical path of light emitted from the light emitting layer to the substrate side to the light emitting layer side between the substrate and the organic electroluminescent element including the light emitting layer, and the optical path The organic electroluminescence display device, wherein the changing means has a plurality of discontinuous reflection surfaces that allow the light to be condensed toward the light extraction region.
<2> The organic electroluminescence device according to <1>, wherein a surface of the discontinuous reflection surface is arcuate in a cross section in the optical path changing direction of the optical path changing unit.
<3> The organic electroluminescence device according to <1>, wherein a surface of the discontinuous reflection surface is linear in a cross section in the optical path changing direction in the optical path changing unit.

  According to the present invention, conventional problems can be solved, and the present invention provides an organic electroluminescence display device that has high light extraction efficiency, can control the light radiation distribution, has no image blur, and is easy to manufacture. Can be provided.

FIG. 1 is a schematic view showing a top emission type organic light emitting display device of the present invention. FIG. 2 is a cross-sectional view schematically showing an optical path changing unit having a first discontinuous reflection surface. FIG. 3 is a cross-sectional view showing an outline of the optical path changing means having the second discontinuous reflection surface. FIG. 4 is a plan view schematically showing the optical path changing means having a Fresnel shape. FIG. 5 is a diagram illustrating a configuration example of a top emission type organic light emitting display device. FIG. 6 is a schematic view showing a top emission type organic light emitting display device using a concave reflecting member.

  The organic electroluminescent display device of the present invention includes a substrate, an organic electroluminescent element including a light emitting layer, and an optical path changing unit, and includes other members as necessary.

A schematic configuration of such an organic light emitting display device will be described with reference to FIG. FIG. 1 shows an outline of the organic electroluminescence display device of the present invention, and the present invention is not limited to the illustrated contents.
The organic electroluminescent display device 100 is a top emission type organic electroluminescent display device, and the optical path changing means 5 is provided between the substrate 1 and the organic electroluminescent display element 20 including the anode 7, the light emitting layer 8, and the cathode 9. Have A transistor 4 for driving the organic light emitting display device 100 is disposed on the substrate 1 through a passivation layer 2. The transistor 4 is joined to the anode 7 by a via 14 to transmit the output voltage of the transistor 4 to the organic light emitting display device 20.
By driving the transistor 4, light is emitted from the light emitting layer 8 in the organic light emitting display element 20. Of the light, the light 60 emitted toward the substrate 1 is changed in optical path toward the light emitting layer 8 by the optical path changing means 5 and can be condensed toward the light extraction region 50. Therefore, it is possible to efficiently extract light from the light extraction region 50.

Further, the optical path changing means 5 has a plurality of discontinuous reflection surfaces and can be formed thin in the depth direction of the via 14, so that the depth for forming the via 14 can also be reduced ( In FIG. 1, refer to T ₂ ), which facilitates manufacture.
That is, the via 14 is formed by forming a contact hole and then burying a contact material in the hole by a chemical vapor deposition method (CVD method) or the like, but the depth with respect to the diameter of the contact hole is long. When the aspect ratio is large, it is difficult to embed the contact material in a desired manner, and when the depth with respect to the diameter of the contact hole is short and the aspect ratio is small, the manufacturing becomes easy.
Therefore, in the organic electroluminescent display device of the present invention, the light extraction efficiency is good and the manufacture is facilitated.
Hereinafter, a specific configuration of the organic light emitting display device will be described in more detail.

-Optical path changing means-
The optical path changing means is disposed between the substrate and the organic electroluminescent element, and has a plurality of discontinuous reflection surfaces.

  The material for forming the optical path changing means is not particularly limited and can be appropriately selected according to the purpose. For example, aluminum, an aluminum alloy, and silver can be used, and these materials can be vapor-deposited. The optical path changing means can be formed.

--Discontinuous reflective surface--
The discontinuous reflection surface can collect light emitted from the light emitting layer toward the substrate toward a light extraction region.
The shape of the discontinuous reflection surface is not particularly limited as long as it allows the light emitted from the light emitting layer to the substrate side to be condensed toward the light extraction region, and is appropriately selected depending on the purpose. Although it can select, the shape in the following 1st discontinuous reflective surface or the following 2nd discontinuous reflective surface is preferable, for example.
In this specification, the light emitted from the light emitting layer to the substrate side includes light emitted from the light emitting layer directly to the substrate side, as well as light once emitted from the light emitting layer to the light extraction side, It includes light that is diffracted to the substrate side and indirectly emitted to the substrate side.
In addition, the light collection based on the optical path changing unit does not need to have a lens function, as long as it changes the optical path of light emitted from the light emitting layer to the substrate side toward the light extraction region. Good.

The height of the discontinuous reflection surface in the thickness direction is preferably 500 nm to 20 μm, more preferably 1 μm to 10 μm, with the height being the top of the cross section in the optical path changing direction in the optical path changing means.
If the height is less than 500 nm, the order of the wavelength of the light to be used is reached, so that a diffraction effect occurs.
When the height exceeds 20 μm, it becomes difficult to process the via structure.

The width in the adjacent direction of the discontinuous reflection surface is preferably 2 μm to 50 μm, and more preferably 5 μm to 20 μm.
If the width is less than 2 μm, the order of the wavelength of the light to be used is reached, so that a diffraction effect occurs.
If the width exceeds 50 μm, the pixel size becomes the same, and improvement in extraction efficiency cannot be expected.
In addition, each of the width | variety of the discontinuous reflective surface which exists multiple may have the same width | variety, and may have a different width | variety.

The optical path changing means may be coated with a planarizing layer to adjust the surface roughness.
In this case, the height in the thickness direction of the discontinuous reflection surface may be limited so that the surface roughness Ra after shrinkage is not more than a predetermined value according to the shrinkage rate characteristics of the flattened layer after coating. preferable.
Moreover, it is preferable to set the width | variety of the adjacent direction of the said discontinuous reflective surface according to this height.
The surface roughness Ra after shrinkage is preferably 50 nm or less, more preferably 10 nm or less, and particularly preferably 5 nm or less.
When the surface roughness Ra after shrinkage is 50 nm or less, the organic EL can emit light without breaking even when the electrode layer is formed.

---- First discontinuous reflecting surface ---
The surface of the first discontinuous reflection surface has an arc shape in a cross section in the optical path changing direction in the optical path changing means.
The first discontinuous reflection surface will be described with reference to FIG. FIG. 2 is a schematic view showing a cross section in the optical path changing direction in the optical path changing means.
As shown in FIG. 2, the optical path changing means 5 has a plurality of discontinuous reflection surfaces 5a. The discontinuous reflection surface 5a has an arcuate surface in the cross section of the light 60 in the optical path changing direction.
With such an optical path changing means having the first discontinuous reflection surface 5a, it is possible to improve the light extraction efficiency by reflection and to control the light distribution.

  The method for forming the optical path changing means having the first discontinuous reflection surface is not particularly limited, and a master mold is prepared by imprint technology using photolithography, a UV curable resin is applied onto the substrate, and the master mold is pressed. And curing.

---- Second discontinuous reflecting surface ---
The surface of the second discontinuous reflection surface is a straight line in the cross section in the optical path changing direction in the optical path changing means.
The second discontinuous reflection surface will be described with reference to FIG. FIG. 3 is a schematic view showing a cross section in the optical path changing direction in the optical path changing means.
As shown in FIG. 3, the optical path changing means 5 has a plurality of discontinuous reflection surfaces 5b. The discontinuous reflecting surface 5b has a straight surface in the cross section in the optical path changing direction of the light 60.
In the case of such an optical path changing means having the second discontinuous reflection surface 5b, by approximating the curved shape (see FIG. 6) when using the concave reflection member with a micro straight line, A similar effect can be expected, and since it is linear, the master mold can be easily manufactured.

  The method for forming the optical path changing means having the second discontinuous reflection surface is not particularly limited, and a master mold is prepared by imprint technology using optical lithography, a UV curable resin is applied onto the substrate, and the master mold is pressed. And curing.

The shape of the optical path changing means having the first discontinuous reflection surface or the second discontinuous reflection surface is not particularly limited and may be appropriately selected depending on the intended purpose. It is preferable to have a Fresnel shape having a plurality of discontinuous reflection surfaces arranged substantially concentrically from a position corresponding to the center of the layer.
For example, FIG. 4 is a diagram showing a plane of the optical path changing means, and as shown in FIG. 4, the optical path changing means 5 has a plurality of discontinuous reflection surfaces 5a (5b) arranged concentrically. It is preferable to be formed as follows.
When the optical path changing means has such a Fresnel shape, it is possible to expect the same effect as the concave reflection member with optimized light extraction efficiency and light distribution.

-Organic electroluminescence device-
Hereinafter, a specific configuration of the organic electroluminescent device will be described in detail.
The organic electroluminescent element has a pair of electrodes, that is, an anode and a cathode, and a light emitting layer between both electrodes. Examples of the functional layer other than the light emitting layer that can be disposed between both electrodes include a hole transport layer, an electron transport layer, a hole block layer, an electron block layer, a hole injection layer, and an electron injection layer.

The organic electroluminescent element preferably has a hole transport layer between the anode and the light emitting layer, and preferably has an electron transport layer between the cathode and the light emitting layer. Furthermore, a hole injection layer may be provided between the hole transport layer and the anode, or an electron injection layer may be provided between the electron transport layer and the cathode.
In addition, a hole transporting intermediate layer (electron blocking layer) may be provided between the light emitting layer and the hole transporting layer, and an electron transporting intermediate layer (hole blocking layer) is provided between the light emitting layer and the electron transporting layer. Layer) may be provided. Each functional layer may be divided into a plurality of secondary layers.

  These functional layers including the light emitting layer can be suitably formed by any of dry film forming methods such as vapor deposition and sputtering, wet coating methods, transfer methods, printing methods, and ink jet methods.

--- Light emitting layer--
The light emitting layer in the present invention receives holes from the anode, the hole injection layer, or the hole transport layer when an electric field is applied, receives electrons from the cathode, the electron injection layer, or the electron transport layer, and regenerates the holes and electrons. It is a layer having a function of providing a bonding field to emit light.
The light emitting layer in the present invention contains a light emitting material. The light emitting layer may be composed of only a light emitting material, or may be a mixed layer of a host material and a light emitting material (in the latter case, the light emitting material may be referred to as “light emitting dopant” or “dopant”). The light emitting material may be a fluorescent light emitting material or a phosphorescent light emitting material, and two or more kinds may be mixed. The host material is preferably a charge transport material. The host material may be one type or two or more types. Furthermore, the light emitting layer may include a material that does not have charge transporting properties and does not emit light.

  Although the thickness of the light emitting layer is not particularly limited, it is usually preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm in terms of external quantum efficiency, and 5 nm to 100 nm. More preferably. Further, the light emitting layer may be a single layer or two or more layers, and each layer may emit light in different emission colors.

--- Luminescent material ---
As the light emitting material in the present invention, any of phosphorescent light emitting materials, fluorescent light emitting materials and the like can be suitably used. The luminescent dopant in the present invention has an ionization potential difference (ΔIp) and an electron affinity difference (ΔEa) of 1.2 eV>ΔIp> 0.2 eV and / or 1.2 eV> with respect to the host compound. A dopant satisfying the relationship of ΔEa> 0.2 eV is preferable from the viewpoint of driving durability.
The light-emitting dopant in the light-emitting layer is contained in an amount of 0.1% by mass to 50% by mass with respect to the total compound mass generally forming the light-emitting layer in the light-emitting layer. To 1 mass% to 50 mass%, and more preferably 2 mass% to 40 mass%.

<Phosphorescent material>
In general, examples of the phosphorescent material include complexes containing a transition metal atom or a lanthanoid atom.
For example, the transition metal atom is not particularly limited, but preferably includes ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum, and more preferably rhenium, iridium. And platinum, more preferably iridium and platinum.

  Examples of the ligand of the complex include G.I. Wilkinson et al., Comprehensive Coordination Chemistry, Pergamon Press, 1987, H.C. Examples include ligands described in Yersin's "Photochemistry and Photophysics of Coordination Compounds" published by Springer-Verlag 1987, Akio Yamamoto "Organic Metal Chemistry-Fundamentals and Applications-" .

  The complex may have one transition metal atom in the compound, or may be a so-called binuclear complex having two or more. Different metal atoms may be contained at the same time.

  Among these, as specific examples of phosphorescent materials, for example, US6303238B1, US6097147, WO00 / 57676, WO00 / 70655, WO01 / 08230, WO01 / 39234A2, WO01 / 41512A1, WO02 / 02714A2, WO02 / 15645A1, WO02 / 44189A1 , WO05 / 19373A2, WO2004 / 108857A1, WO2005 / 042444A2, WO2005 / 042550A1, JP2001-247859, JP2002-302671, JP2002-117978, JP2003-133074, JP2002-235076, JP2003 -123982, JP2002-170684, EP121257, JP2002-226495, JP2 02-234894, JP-A-2001-247659, JP-A-2001-298470, JP-A-2002-173675, JP-A-2002-203678, JP-A-2002-203679, JP-A-2004-357542, JP-A-2006-93542, JP-A-2006- 261623, JP-A-2006-256999, JP-A-2007-19462, JP-A-2007-84635, JP-A-2007-96259, and the like, and more preferable examples of the light-emitting material include Ir. Complexes, Pt complexes, Cu complexes, Re complexes, W complexes, Rh complexes, Ru complexes, Pd complexes, Os complexes, Eu complexes, Tb complexes, Gd complexes, Dy complexes, and Ce complexes. Particularly preferred is an Ir complex, a Pt complex, or a Re complex, among which an Ir complex or a Pt complex containing at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond. Or a Re complex. Furthermore, an Ir complex, a Pt complex, or a Re complex containing a tridentate or higher polydentate ligand is particularly preferable from the viewpoints of luminous efficiency, driving durability, chromaticity, and the like.

  Specific examples of the phosphorescent light-emitting material that can be used in the present invention include the following compounds, but are not limited thereto.

<Fluorescent material>
As the fluorescent material, generally, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin, pyran, perinone, oxadiazole, aldazine, pyralidine, cyclohexane Pentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compounds, condensed polycyclic aromatic compounds (such as anthracene, phenanthroline, pyrene, perylene, rubrene, or pentacene), 8 -Metal complexes of quinolinol, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene, polyphenylene, polyphenylene vinylene, etc. Rimmer compounds, organic silane, and the like, and their derivatives.

---- Host material ---
As the host material used for the light emitting layer, a hole transporting host material having excellent hole transportability (may be described as a hole transportable host) and an electron transporting host compound having excellent electron transportability (electron transport) May be described as a sex host).

<Hole transportable host>
Specific examples of the hole transporting host used in the light emitting layer include the following materials. Pyrrole, indole, carbazole, azaindole, azacarbazole, triazole, oxazole, oxadiazole, pyrazole, imidazole, thiophene, polyarylalkane, pyrazoline, pyrazolone, phenylenediamine, arylamine, amino-substituted chalcone, styrylanthracene, fluorenone Hydrazone, stilbene, silazane, aromatic tertiary amine compound, styrylamine compound, aromatic dimethylidin compound, porphyrin compound, polysilane compound, poly (N-vinylcarbazole), aniline copolymer, thiophene oligomer, Examples thereof include conductive polymer oligomers such as polythiophene, organic silanes, carbon films, and derivatives thereof.
Preferred are indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, and thiophene derivatives, and more preferred are those having a carbazole group in the molecule. In particular, a compound having a t-butyl substituted carbazole group is preferable.

<Electron transporting host>
Specific examples of the electron transporting host used in the light emitting layer include the following materials. Pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazol, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluorenylidenemethane, distyryl Metal complexes of pyrazine, fluorine-substituted aromatic compounds, heterocyclic tetracarboxylic anhydrides such as naphthaleneperylene, phthalocyanines, and derivatives thereof (which may form condensed rings with other rings), 8-quinolinol derivatives And various metal complexes represented by metal complexes having metal phthalocyanine, benzoxazole or benzothiazol as a ligand. Among them, a metal complex compound is preferable from the viewpoint of durability, and a metal complex having a ligand having at least one nitrogen atom, oxygen atom, or sulfur atom coordinated to a metal is more preferable. Examples of the metal complex electron transporting host are described in, for example, JP-A No. 2002-235076, JP-A No. 2004-214179, JP-A No. 2004-221106, JP-A No. 2004-221665, JP-A No. 2004-221068, JP-A No. 2004-327313, and the like. The compound of this is mentioned.

  Specific examples of the hole transporting host material and the electron transporting host material that can be used in the present invention include, but are not limited to, the following compounds.

--- Hole injection layer, hole transport layer-
The hole injection layer and the hole transport layer are layers having a function of receiving holes from the anode or the anode side and transporting them to the cathode side. The hole injecting material and hole transporting material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyrrole derivatives, carbazole derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, polyarylalkane derivatives, pyrazoline derivatives, pyrazolone derivatives, phenylenediamine derivatives, arylamine derivatives, amino-substituted chalcone derivatives, styryl Anthracene derivatives, fluorenone derivatives, hydrazone derivatives, stilbene derivatives, silazane derivatives, aromatic tertiary amine compounds, styrylamine compounds, aromatic dimethylidin compounds, phthalocyanine compounds, porphyrin compounds, thiophene derivatives, organosilane derivatives, carbon, And the like.

The hole injection layer and the hole transport layer may contain an electron accepting dopant. As the electron-accepting dopant introduced into the hole-injecting layer and the hole-transporting layer, an inorganic compound or an organic compound can be used as long as it has an electron-accepting property and oxidizes an organic compound.
Specifically, examples of the inorganic compound include metal halides such as ferric chloride, aluminum chloride, gallium chloride, indium chloride, and antimony pentachloride, metal oxides such as vanadium pentoxide, and molybdenum trioxide. In the case of an organic compound, a compound having a nitro group, halogen, cyano group, trifluoromethyl group or the like as a substituent, a quinone compound, an acid anhydride compound, fullerene, or the like can be preferably used.
These electron-accepting dopants may be used alone or in combination of two or more. Although the usage-amount of an electron-accepting dopant changes with kinds of material, it is preferable that it is 0.01 mass%-50 mass% with respect to hole transport layer material, and it is 0.05 mass%-20 mass%. More preferably, it is especially preferable that it is 0.1 mass%-10 mass%.

  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.

--Electron injection layer, electron transport layer--
The electron injection layer and the electron transport layer are layers having a function of receiving electrons from the cathode or the cathode side and transporting them to the anode side. The electron injection material and the electron transport material used for these layers may be a low molecular compound or a high molecular compound.
Specifically, pyridine derivatives, quinoline derivatives, pyrimidine derivatives, pyrazine derivatives, phthalazine derivatives, phenanthroline derivatives, triazine derivatives, triazole derivatives, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, fluorenone derivatives, anthraquinodimethane derivatives, anthrone Derivatives, diphenylquinone derivatives, thiopyran dioxide derivatives, carbodiimide derivatives, fluorenylidenemethane derivatives, distyrylpyrazine derivatives, naphthalene, perylene and other aromatic ring tetracarboxylic acid anhydrides, phthalocyanine derivatives, 8-quinolinol derivative metal complexes, Metal phthalocyanines, various metal complexes represented by metal complexes with benzoxazole and benzothiazole as ligands, organosilane derivatives represented by siloles Body, or the like is preferably a layer containing.

The electron injection layer or the electron transport layer may contain an electron donating dopant. The electron-donating dopant introduced into the electron-injecting layer or the electron-transporting layer is not limited as long as it has an electron-donating property and has a property of reducing an organic compound, such as an alkali metal such as Li, an alkaline earth metal such as Mg, Transition metals including rare earth metals and reducing organic compounds are preferably used. As the metal, a metal having a work function of 4.2 eV or less can be preferably used. Specifically, Li, Na, K, Be, Mg, Ca, Sr, Ba, Y, Cs, La, Sm, Gd , And Yb. Examples of the reducing organic compound include nitrogen-containing compounds, sulfur-containing compounds, and phosphorus-containing compounds.
These electron donating dopants may be used alone or in combination of two or more. Although the usage-amount of an electron donating dopant changes with kinds of material, it is preferable that it is 0.1 mass%-99 mass% with respect to electron transport layer material, and it is 1.0 mass%-80 mass%. Is more preferable, and 2.0 mass% to 70 mass% is particularly preferable.

  The electron injection layer and the electron transport layer may have a single-layer structure made of one or more of the materials described above, or may have a multilayer structure made up of a plurality of layers having the same composition or different compositions. .

--Hole blocking layer, electron blocking layer--
The hole blocking layer is a layer having a function of preventing holes transported from the anode side to the light emitting layer from passing through to the cathode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the cathode side. .
On the other hand, the electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the light emitting layer from passing to the anode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the anode side. .
Examples of the compound constituting the hole blocking layer include aluminum complexes such as BAlq, triazole derivatives, phenanthroline derivatives such as BCP, and the like. As an example of the compound constituting the electron blocking layer, for example, those mentioned as the hole transport material described above can be used.
The thickness of the hole blocking layer and the electron blocking layer is preferably 1 nm to 500 nm, more preferably 5 nm to 200 nm, and even more preferably 10 nm to 100 nm. In addition, the hole blocking layer and the electron blocking 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. .

--- Electrode--
The organic electroluminescent element includes a pair of electrodes, that is, an anode and a cathode. In view of the properties of the light emitting element, at least one of the anode and the cathode is preferably transparent.
Usually, the anode only needs to have a function as an electrode for supplying holes to the organic compound layer, and the cathode only needs to have a function as an electrode for injecting electrons into the organic compound layer. The shape, structure, size, and the like are not particularly limited, and can be appropriately selected from known electrode materials according to the use and purpose of the light-emitting element. As a material which comprises an electrode, a metal, an alloy, a metal oxide, an electroconductive compound, or a mixture thereof etc. are mentioned suitably, for example.

  Specific examples of the material constituting the anode include, for example, tin oxide (ATO, FTO) doped with antimony or fluorine, tin oxide, zinc oxide, indium oxide, indium tin oxide (ITO), indium zinc oxide (IZO). ) Conductive metal oxides, metals such as gold, silver, chromium, nickel, and mixtures or laminates of these metals and conductive metal oxides, inorganic conductive materials such as copper iodide and copper sulfide, Examples thereof include organic conductive materials such as polyaniline, polythiophene, and polypyrrole, and laminates of these with ITO. Among these, conductive metal oxides are preferable, and ITO is particularly preferable from the viewpoints of productivity, high conductivity, transparency, and the like.

  Specific examples of the material constituting the cathode include, for example, alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium -Potassium alloys, lithium-aluminum alloys, magnesium-silver alloys, indium, and rare earth metals such as ytterbium. These may be used alone, but two or more can be suitably used in combination from the viewpoint of achieving both stability and electron injection. Among these, alkali metals and alkaline earth metals are preferable from the viewpoint of electron injection properties, and materials mainly composed of aluminum are preferable from the viewpoint of excellent storage stability. The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  There is no restriction | limiting in particular about the formation method of the said electrode, According to a well-known method, it can carry out. For example, a material constituting the electrode from a wet method such as a printing method, a coating method, a physical method such as a vacuum deposition method, a sputtering method, or an ion plating method, or a chemical method such as CVD or plasma CVD method. In consideration of the suitability, the film can be formed on the substrate according to an appropriately selected method. For example, when ITO is selected as the anode material, it can be formed according to a direct current or high frequency sputtering method, a vacuum deposition method, an ion plating method, or the like. When a metal or the like is selected as the cathode material, one or more of them can be formed simultaneously or sequentially according to a sputtering method or the like.

  In addition, when patterning is performed when forming the electrode, it may be performed by chemical etching such as photolithography, or may be performed by physical etching using a laser or the like. It may be performed by sputtering or the like, or may be performed by a lift-off method or a printing method.

-Board-
It is preferable that the optical path changing unit and the organic electroluminescent element are arranged in this order on the substrate.
An intermediate layer may be provided between the optical path changing unit and the substrate.
Examples of the substrate include inorganic materials such as yttria-stabilized zirconia (YSZ) and glass (such as alkali-free glass and soda lime glass), polyesters such as polyethylene terephthalate, polybutylene phthalate, and polyethylene naphthalate, polystyrene, polycarbonate, and polyethersulfone. , Substrates made of organic materials such as polyarylate, polyimide, polycycloolefin, norbornene resin, and poly (chlorotrifluoroethylene).

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

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

-Other components-
There is no restriction | limiting in particular as said other member, According to the objective, it can select suitably, For example, a protective layer, a sealing container, and a fine particle content layer are mentioned.

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

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

--Sealing--
Further, the organic electroluminescent element may be entirely sealed using a sealing container. Further, a moisture absorbent or an inert liquid may be sealed in a space between the sealing container and the light emitting element. Although it does not specifically limit as a moisture absorber, For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, calcium chloride, magnesium chloride, copper chloride Cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, magnesium oxide, and the like. The inert liquid is not particularly limited, and examples thereof include paraffins, liquid paraffins, fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether, chlorinated solvents, and silicone oils. Can be mentioned.

  Moreover, the method of sealing with the resin sealing layer shown below is also used suitably.

---- Resin sealing layer ---
The organic electroluminescent element preferably suppresses element performance deterioration due to oxygen or moisture from the atmosphere by a resin sealing layer.
The resin material of the resin sealing layer is not particularly limited, and acrylic resin, epoxy resin, fluorine resin, silicon resin, rubber resin, ester resin, or the like can be used. An epoxy resin is preferable from the viewpoint of function. Among the epoxy resins, a thermosetting epoxy resin or a photocurable epoxy resin is preferable.
The method for producing the resin sealing layer is not particularly limited, and examples thereof include a method of applying a resin solution, a method of pressure bonding or thermocompression bonding of a resin sheet, and a method of dry polymerization by vapor deposition or sputtering.

---- Sealing adhesive ---
The sealing adhesive has a function of preventing intrusion of moisture and oxygen from the end portion. As the material of the sealing adhesive, the same material as that used for the resin sealing layer can be used. Among these, epoxy adhesives are preferable from the viewpoint of moisture prevention, and among them, a photocurable adhesive or a thermosetting adhesive is preferable.
It is also preferable to add a filler to the above material. The filler added to the sealant is preferably an inorganic material such as SiO ₂ , SiO (silicon oxide), SiON (silicon oxynitride) or SiN (silicon nitride). Addition of the filler increases the viscosity of the sealant, improves processing suitability, and improves moisture resistance.
The sealing adhesive may contain a desiccant. As the desiccant, barium oxide, calcium oxide, or strontium oxide is preferable. The amount of the desiccant added to the sealing adhesive is preferably 0.01% by mass to 20% by mass, and more preferably 0.05% by mass to 15% by mass. If the amount is less than this, the effect of adding the desiccant is diminished. On the other hand, when it is more than this, it becomes difficult to uniformly disperse the desiccant in the sealing adhesive, which is not preferable.
In the present invention, the sealing adhesive containing the desiccant can be applied in an arbitrary amount with a dispenser or the like, and the second substrate can be overlaid after application and cured by being cured.

Note that, as described above, the organic light emitting display device may be configured to include a fine particle-containing layer.
There is no restriction | limiting in particular as long as the effect of this invention is not impaired as a material of the said fine particle content layer, According to the objective, it can select suitably.

<Drive>
The organic electroluminescence device emits light by applying a direct current (which may include an alternating current component if necessary, the same applies hereinafter) voltage (usually 2 to 15 volts) or a direct current between the anode and the cathode. Can be obtained.
The organic electroluminescence device can be applied to an active matrix by a thin film transistor (TFT). As the active layer of the thin film transistor, amorphous silicon, high temperature polysilicon, low temperature polysilicon, microcrystalline silicon, oxide semiconductor, organic semiconductor, carbon nanotube, or the like can be used. As the organic electroluminescence element, the thin film transistor described in each specification of WO2005 / 088726, JP-A-2006-165529, US2008 / 0237598A1, and the like can be applied.

  The organic electroluminescence device can improve the light extraction efficiency by various known devices. For example, by controlling the refractive index of the substrate / ITO layer / organic layer, and controlling the film thickness of the substrate / ITO layer / organic layer, the light extraction efficiency can be improved and the external quantum efficiency can be improved. It is. The light extraction method from the organic electroluminescence device is a top emission method.

<Top emission type organic EL display device>
For example, as shown in FIG. 5, the top emission type organic EL display device includes a glass substrate 1 (refractive index: about 1.5) and a passivation layer formed on the glass substrate 1 and made of SiNx, SiON, or the like. 2, disposed on the passivation layer 2, an interlayer insulating layer 3 made of acrylic resin, and the like, disposed on the passivation layer 2 and adjacent to the interlayer insulating layer 3, an organic thin film transistor (TFT) 4, Arranged on the insulating layer 3, disposed on the optical path changing means 5, the optical path changing means 5, disposed on the organic resin material (refractive index: about 1.5), the planarizing layer 6, and the planarizing layer 6. A transparent electrode (anode) 7 (refractive index: about 1.9) made of ITO or the like, and an organic compound layer 8 (refractive index: about 1.8) disposed on the transparent electrode (anode) 7 and including a light emitting layer, etc. ) And organic compound layer 8 The counter electrode (semi-transmissive cathode) 9 made of aluminum, silver or the like is disposed on the planarizing layer 6, and is formed on the transparent electrode (anode) 7, the organic compound layer 8, and the counter electrode (semi-transmissive cathode) 9. A bank 10 made of acrylic resin and the like, and a sealing layer 11 (refractive index: about 1.75) made of SiNx, SiON, etc., arranged on the counter electrode (semi-transmissive cathode) 9; An adhesive layer 12 (refractive index: about 1.55) disposed on the sealing layer 11 and made of an epoxy resin, and a substrate 13 (refractive index: about 1) disposed on the adhesive layer 12 and made of glass or the like. 5).
The interlayer insulating layer 3 and the planarizing layer 6 also have a function as a planarizing film that planarizes the organic thin film transistor (TFT) 4.
Vias 14 are formed in the interlayer insulating layer 3, the optical path changing means 5 and the planarizing layer 6, and the transparent electrode (anode) 7 and the organic thin film transistor (TFT) 4 are connected.
Further, since the thickness of the planarizing layer 6 is as thin as 2 μm to 10 μm, the via 14 can be easily formed, and the manufacturing cost can be reduced.
Since the planarizing layer 6 contains fine particles having a refractive index higher than that of the organic resin material, it is emitted from the light emitting layer in the organic compound layer 8, passes through the transparent electrode (anode) 7, and passes through the optical path. The reflected light reflected by the changing unit 5 can be scattered to improve the light extraction efficiency.

The organic light emitting display device may have a resonator structure. For example, a multilayer mirror made of a plurality of laminated films having different refractive indexes, a transparent or translucent electrode, a light emitting layer, and a metal electrode are superimposed on a transparent substrate. The light generated in the light emitting layer resonates repeatedly with the multilayer mirror and the metal electrode as a reflection plate.
In another preferred embodiment, a transparent or translucent electrode and a metal electrode each function as a reflecting plate on the transparent substrate, and light generated in the light emitting layer repeats reflection and resonates between them.
In order to form the resonant structure, the optical path length determined from the effective refractive index of the two reflecting plates and the refractive index and thickness of each layer between the reflecting plates is set to an optimum value for obtaining a desired resonant wavelength. Adjusted. The calculation formula in the case of the first embodiment is described in JP-A-9-180883. The calculation formula in the case of the second aspect is described in Japanese Patent Application Laid-Open No. 2004-127795.

  As a method of making the organic electroluminescent display device 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)), a three-color light emitting method in which organic electroluminescent elements that emit light corresponding to green (G) and red (R)) are arranged on a substrate, and white light emitted by a white light emitting organic electroluminescent element through a color filter. There are known a white method for separating primary colors, a color conversion method for converting blue light emitted by an organic electroluminescent element for blue light emission into red (R) and green (G) through a fluorescent dye layer, and the like. Moreover, the planar light source of a desired luminescent color can be obtained by using combining the organic electroluminescent element of the different luminescent color obtained by the said method. 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.

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

Example 1
An optical path changing means having a plurality of discontinuous reflection surfaces was formed by using a known optical imprint technique. Specifically, it was formed by the following method.

A photosensitive resist was applied to the quartz substrate for the master mold to form a photosensitive resist layer on the quartz substrate.
The photosensitive resist layer was subjected to gray scale exposure through a photomask.
The photomask used was a concentric circle from the position corresponding to the center of the pixel on which the optical path changing means is provided, and a Fresnel shape with the unevenness height limited to 2 μm as shades (irregularities).
The photosensitive resist layer after grayscale exposure was developed and then etched to produce a concavo-convex shape having a plurality of discontinuous reflective surfaces on a quartz substrate, which was used as a master mold.

A photosensitive resin was applied to the substrate to form a photosensitive resin layer. The photosensitive resin layer was cured by pressing a master mold and irradiating with ultraviolet rays.
An optical path changing means having a plurality of discontinuous reflection surfaces was formed by vapor-depositing aluminum on the cured photosensitive resin by a sputtering apparatus.

In this optical path changing means, a flattening layer made of a transparent resin (acrylic resin) was disposed, and the upper part of the optical path changing means was flattened.
Via holes were formed to the depth of the transistor in the organic electroluminescent element by a laser via device with respect to the optical path changing means formed in this way.
Thereafter, a transparent electrode (ITO) is formed so as to be connected to the transistor through the via hole, and the organic light emitting layer is further formed thereon to manufacture the organic light emitting display according to Example 1. did.

(Comparative Example 1)
The organic electroluminescent display device in Comparative Example 1 is manufactured in the same manner as in Example 1 except that a planar reflective layer is used instead of the optical path changing means having a plurality of discontinuous reflective surfaces in Example 1. did.

(Evaluation)
Measurement of light extraction efficiency in an organic electroluminescence display device comprising an organic electroluminescence display device having an optical path changing means having a plurality of discontinuous reflection surfaces and an organic electroluminescence display device having a planar reflection layer according to Example 1. Evaluation was performed.
As the measuring method, using an integrating sphere, total bundle measurement was performed for light emission in each organic light emitting display device.
As a result of comparing the light extraction efficiency of the organic electroluminescent display device according to Comparative Example 1 and the organic electroluminescent display device according to Example 1 based on the measured light amount, the organic electroluminescent display according to Comparative Example 1 was compared. The light extraction efficiency of the organic light emitting display according to Example 1 with respect to the device was 1.6 times.

  The organic electroluminescent display device of the present invention is suitable for use as a display device in various devices because it has high light extraction efficiency, can control the radiation distribution of light, does not blur images, and is easy to manufacture.

1 substrate 2 passivation layer 3 interlayer insulation layer 4 transistor (TFT)
5 Optical path changing means 5a, 5b Discontinuous reflection surface 6 Flattening layer 7 Transparent electrode (anode)
8 Light emitting layer (organic compound layer)
9 Counter electrode (cathode)
10 Bank 11 Sealing Layer 12 Adhesive Layer 13 Substrate 14 Via 50 Light Extraction Area 60 Light (Optical Path)
100, 200 Organic electroluminescent display device

Claims (3)

Between the substrate and the organic electroluminescent element including the light emitting layer, an optical path changing means capable of changing the light path of the light emitted from the light emitting layer to the substrate side to the light emitting layer side,
The organic light emitting display device, wherein the optical path changing means has a plurality of discontinuous reflection surfaces that allow the light to be condensed toward a light extraction region.   2. The organic electroluminescent device according to claim 1, wherein a surface of the discontinuous reflection surface is arcuate in a cross section in the optical path changing direction in the optical path changing means.   2. The organic electroluminescent device according to claim 1, wherein a surface of the discontinuous reflection surface is linear in a cross section of the optical path changing unit in the optical path changing direction.