JP2022148337A - Light-emitting device and light extraction layer - Google Patents

Abstract

To provide a light-emitting device capable of longer and stable driving while improving the light extraction efficiency, and a light extraction layer that is suitably usable for the light-emitting device.SOLUTION: A light-emitting device according to an embodiment includes a transparent substrate, a transparent electrode, a reflection electrode, and a light-emitting layer. The transparent electrode is disposed on the transparent substrate, and the light-emitting layer is disposed between the transparent electrode and the reflection electrode. The light-emitting device includes a light extraction layer disposed on an optical path of light emitted from the light-emitting layer, and is used to extract light emitted from the light-emitting layer to the outside. The light extraction layer includes a light scattering layer including a base material and scattering particles with a refractive index different from that of the base material. The transmission parameter of resin in the light scattering layer is 4.0×10-4 m/h0.5 or less.SELECTED DRAWING: Figure 1

Description

The present invention relates to light emitting devices and light extraction layers.

A light-emitting device includes a device having a transparent substrate, a transparent electrode provided on the transparent substrate, a reflective electrode paired with the transparent electrode, and a light-emitting layer disposed between the transparent electrode and the reflective electrode. In such a light-emitting device, one of the transparent electrode and the reflective electrode is used as an anode, and the other is used as a cathode to supply electric power to the light-emitting layer. This causes light to be generated in the light-emitting layer. Light generated in the light-emitting layer passes through the transparent electrode and the transparent substrate and is output from the transparent substrate side. Of the light generated in the light-emitting layer, the light traveling toward the reflective electrode is reflected by the reflective electrode, transmitted through the transparent electrode and the transparent substrate, and output from the transparent substrate. As described above, in a light-emitting device using a transparent substrate, light is output from the transparent substrate side, but part of the light generated in the light-emitting layer is confined in the transparent substrate and the transparent electrode. Therefore, it is known to use a light extraction layer as disclosed in Patent Document 1 in order to improve the luminous efficiency of the light emitting device.

WO2014/087462

In order to stably drive a light-emitting device over a long period of time, high sealing performance against gases such as water vapor and oxygen is required. Therefore, improvements in light extraction efficiency must be made without compromising the stability of the light emitting device. However, when a light extraction layer is provided as in Patent Document 1, the period during which the light emitting device can be stably driven may be reduced even if the light extraction efficiency is improved.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a light-emitting device that can be stably driven for a longer period of time while improving light-extraction efficiency, and a light-extraction layer that can be suitably applied to the light-emitting device.

By focusing on the transmission parameter of the light scattering layer (specifically, the transmission parameter of the resin contained in the light scattering layer), the inventors of the present application have improved the light extraction efficiency while maintaining stability for a longer period of time. The inventors have found that it is possible to realize a light-emitting device that can be driven by a light-emitting device, leading to the present invention.

A light-emitting device according to one aspect of the present invention includes a transparent substrate, a transparent electrode, a reflective electrode, and a light-emitting layer. The transparent electrode is disposed on the transparent substrate, and the light-emitting layer includes the transparent electrode. and the reflective electrode, the light-emitting device is arranged on the optical path of the light emitted from the light-emitting layer, for extracting the light emitted from the light-emitting layer to the outside A light extraction layer is provided, the light extraction layer has a light scattering layer containing a base material and scattering particles having a refractive index different from that of the base material, and the transmission parameter of the resin contained in the light scattering layer is 4. .0×10 ⁻⁴ m/h ^0.5 or less.

The light emitting device has a light extraction layer on the optical path of light emitted from the light emitting layer. Since the light extraction layer has the light scattering layer, the light incident on the light extraction layer is easily extracted to the outside of the light emitting device. In the light emitting device having the above structure, the transmission parameter of the resin contained in the light scattering layer is 4.0×10 ⁻⁴ m/h ^0.5 or less. This enables stable driving while improving the light extraction efficiency.

A barrier layer having a refractive index equal to or higher than the refractive index of the base material is further provided between the light extraction layer and the transparent electrode, even if the water vapor permeability of the transparent substrate is lower than the water vapor permeability of the barrier layer. good. In this case, it is difficult for water vapor or the like to enter the light-emitting layer from the transparent substrate side.

The water vapor permeability of the transparent substrate may be less than 1/10 of the water vapor permeability of the barrier layer. In this case, it is more difficult for water vapor or the like to enter the light-emitting layer from the transparent substrate side.

In the light emitting device according to one embodiment, the light extraction layer is arranged between the transparent substrate and the transparent electrode, and the light extraction layer is arranged on the transparent electrode side of the light scattering layer. The light extraction layer may be a layer that satisfies the following condition (A).
Condition (A):
A laminate obtained by forming a first layer having the same structure as the light scattering layer on the transparent substrate by a coating method and forming a second layer having the same structure as the flattening layer by a coating method. The first hue of is called b ^* _1, and after degassing the laminate, the laminate was heat-treated for 15 minutes ± 10 seconds so that the temperature of the laminate was 230 ° C ± 5 ° C. The difference Δb ^* between the first hue and the second hue represented by the formula (I) is 5 or less when the second hue of the laminate afterward is referred to as b ^* _2.
Δb ^* =(b ^* _2)-(b ^* _1) (I)

When the light extraction layer satisfies the above condition (A), the light extraction efficiency is further improved.

The light-emitting layer may be an organic light-emitting layer. In this case, the light emitting device functions as an organic electroluminescent device.

A light extraction layer according to another aspect of the present invention includes a light scattering layer having a base material and scattering particles having a refractive index different from that of the base material, and a resin contained in the light scattering layer has a transmission parameter of 4. .0×10 ⁻⁴ m/h ^0.5 or less.

In the light extraction layer, the transmission parameter of the resin contained in the light scattering layer is 4.0×10 ⁻⁴ m/h ^0.5 or less. Therefore, when the light extraction layer is applied to, for example, a light emitting device, the light emitting device can be stably driven while improving the light extraction efficiency.

According to the present invention, it is possible to provide a light-emitting device that can be stably driven for a longer period of time while improving light-extraction efficiency, and a light-extraction layer that can be suitably applied to the light-emitting device.

FIG. 1 is a diagram illustrating the basic configuration of an organic electroluminescence device (organic EL device), which is an example of a light-emitting device according to one embodiment. FIG. 2 is a schematic diagram of an example for explaining the configuration of the light extraction layer. FIG. 3 is a drawing for explaining an organic EL device (light-emitting device) provided with a sealing member. FIG. 4 is a drawing for explaining a method of calculating a transmission parameter. FIG. 5 is a plan view of a measurement sample used for calculating transmission parameters. FIG. 6 is a table showing compositions of photocurable resin compounds used in experiments. FIG. 7 is a chart showing experimental results.

Embodiments of the present invention will be described. First, the “transmission parameter K” used in the present disclosure will be explained.

<Transmission parameter>
The permeation parameter K is the relationship between time and distance when moisture permeates in the direction of the material from the interface when a material not containing moisture and a certain atmosphere containing moisture are brought into contact at one interface. is a parameter that represents

The mechanism by which moisture permeates through a material that does not contain moisture is (a) the dissolution of moisture from the atmosphere around the material to the surface of the material, and (b) the concentration gradient of moisture in the material as the driving force. Diffusion, including.

Of these, Henry's law of gas dissolution is applied to the above (a). Regarding (b) above, since the distance between the surface of the material and the tip where the moisture reaches is extended every moment, if the thickness of the material is constant, the concentration gradient of moisture in that section is , and Fick's second law applies. That is, as the distance between the surface of the material and the tip reached by the moisture increases with the passage of time, the concentration gradient at any point in that section decreases, so the speed at which the distance increases decreases.

境界条件は、材料表面の水分濃度をＣ_０として、次のように与えられる。
Ｃ（ｘ，０）＝０
Ｃ（０，ｔ）＝Ｃ_０
Ｃ（∞，ｔ）＝０ A mathematical analysis of this results in the following. C is the moisture concentration at an arbitrary point x in the direction from the material surface to the material side when a material not containing moisture and a certain atmosphere containing moisture are brought into contact at one interface for time t, and D is the diffusion coefficient of the material. Then, according to Fick's second law, the relationship of formula (1) holds.

The boundary conditions are given as follows, where _C0 is the moisture concentration on the material surface.
C(x,0)=0
C(0,t)= _C0
C(∞, t) = 0

Here, next, variable conversion is performed using z shown in Equation (2).

式（１）の右辺に対して式（２）を用いた変数変換は次のとおりである。

すなわち、以下の式（３）、式（４）および式（５）が成立する。

式（６）中のＡは積分定数である。 The transformation of variables using equation (2) on the left side of equation (1) is as follows.

The transformation of variables using equation (2) on the right side of equation (1) is as follows.

That is, the following formulas (3), (4) and (5) are established.

A in Equation (6) is the constant of integration.

The above equations (4) to (6) show that z=x/2(Dt) ^1/2 for a certain C is constant, and the diffusion coefficient D is a material-specific constant, so a certain There is a constant x/t ^1/2 for C. That is, if the reaching distance x _t of water at the moment when C>0, that is, at a certain time t is known, x _t /t ^1/2 peculiar to the material can be obtained. Therefore, in this disclosure, the transmission parameter K is defined by the following equation.
K= _xt /t1/ ² (7a)

Next, a light extraction layer and a light emitting device including the same according to one embodiment will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals, and overlapping descriptions are omitted. The dimensional proportions of the drawings do not necessarily match those of the description.

FIG. 1 is a diagram illustrating the basic configuration of an organic electroluminescence device (organic EL device), which is an example of a light-emitting device according to one embodiment.

The organic EL device 10 includes a transparent substrate 11 , a light extraction layer 12 , a transparent electrode 13 , an organic EL layer (device functional layer) 14 and a reflective electrode 15 . One of the transparent electrode 13 and the reflective electrode 15 functions as an anode, and the other functions as a cathode. In the following, unless otherwise specified, a configuration in which the transparent electrode 13 functions as an anode and the reflective electrode 15 functions as a cathode will be described.

The transparent substrate 11 is transparent to light (including visible light) output from the organic EL device 10 . The transparent substrate 11 may be a rigid substrate such as a glass substrate and a quartz substrate, or a flexible substrate such as a plastic substrate and a polymer film. A flexible substrate is a substrate that can be bent without being sheared or broken even when a predetermined force is applied to the substrate. An example of the refractive index of the transparent substrate 11 is 1.4 or more and 1.8 or less. An example of the water vapor transmission rate (WVTR) of the transparent substrate 11 is 1×10 ⁻⁴ g/(m ² ·day) or less.

When the transparent substrate 11 is a rigid substrate, the thickness of the transparent substrate 11 is, for example, 50 μm to 1100 μm. When the transparent substrate 11 is a flexible substrate, the thickness of the transparent substrate 11 is, for example, 10 μm to 700 μm.

The light extraction layer 12 is arranged on the transparent substrate 11 . The light extraction layer 12 is a layer for extracting light generated within the organic EL device 10 to the outside. The light extraction layer 12 will be described later.

An electrode exhibiting optical transparency is used for the transparent electrode 13 . As the electrode exhibiting light transmittance, thin films of metal oxides, metal sulfides, metals, and the like with high electrical conductivity and laminates thereof can be used, and thin films with high light transmittance are preferably used. The transparent electrode 13 may have a network structure made of a conductor (for example, metal). The thickness of the transparent electrode 13 can be determined in consideration of light transmittance, electrical conductivity, and the like. The thickness of the transparent electrode 13 is usually 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 30 nm to 500 nm.

Materials for the transparent electrode 13 include, for example, indium oxide, indium tin oxide (abbreviated as ITO), indium zinc oxide (abbreviated as IZO), zinc oxide, and aluminum-doped zinc oxide (Aluminium Zinc Oxide: AZO), Gallium Zinc Oxide (GZO), Tin Oxide, Antimony Tin Oxide (ATO), Fluorine Tin Oxide (FTO), gold, platinum, silver, copper, etc., and among these, ITO or IZO is preferred. The transparent electrode 13 can be formed as a thin film made of the exemplified materials. Organic materials such as polyaniline and its derivatives, polythiophene and its derivatives may be used as the material of the transparent electrode 13 . In this case, the transparent electrode 13 can be formed as a transparent conductive film.

The transparent electrode 13 can be formed by a dry film-forming method. Examples of the dry film forming method include a vacuum deposition method, a sputtering method, an ion plating method, and a CVD method.

The organic EL layer 14 is arranged on the transparent electrode 13 . The organic EL layer 14 is positioned between the transparent electrode 13 and the reflective electrode 15 . The size of the organic EL layer 14 (the size when viewed in the thickness direction) is smaller than the transparent substrate 11 . The organic EL layer 14 is a functional layer that contributes to light emission of the organic EL device 10 such as charge transfer and charge recombination according to power applied to the transparent electrode 13 and the reflective electrode 15 . The organic EL layer 14 has a light-emitting layer (organic light-emitting layer) 14a.

The light emitting layer 14a is a functional layer that emits light (including visible light). The thickness of the light emitting layer 14a is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm.

The light-emitting layer 14a is usually formed of an organic material that mainly emits at least one of fluorescence and phosphorescence, or the organic material and a dopant material that assists the organic material. Therefore, the light-emitting layer 14a is an organic light-emitting layer. The organic substance contained in the light-emitting layer 14a may be a low-molecular compound or a high-molecular compound.

Organic substances that mainly emit at least one of fluorescence and phosphorescence include the following dye-based materials, metal complex-based materials, polymer-based materials, and the like.

Examples of dye materials include cyclopentamine or its derivatives, tetraphenylbutadiene or its derivatives, triphenylamine or its derivatives, oxadiazole or its derivatives, pyrazoloquinoline or its derivatives, distyrylbenzene or its derivatives, di styrylarylene or derivatives thereof, pyrrole or derivatives thereof, thiophene ring compounds, pyridine ring compounds, perinone or derivatives thereof, perylene or derivatives thereof, oligothiophene or derivatives thereof, oxadiazole dimers or derivatives thereof, pyrazoline dimers or derivatives thereof, Examples include quinacridone or its derivatives, coumarin or its derivatives, and the like.

Examples of metal complex materials include rare earth metals such as Tb, Eu, and Dy, or Al, Zn, Be, Pt, Ir, etc., as central metals, and oxadiazole, thiadiazole, phenylpyridine, phenylbenzimidazole, and quinoline. A metal complex having a structure or the like as a ligand can be mentioned. Examples of metal complexes include metal complexes that emit light from a triplet excited state such as iridium complexes and platinum complexes, aluminum quinolinol complexes, benzoquinolinol beryllium complexes, benzoxazolyl zinc complexes, benzothiazole zinc complexes, azomethyl zinc complexes, porphyrin zinc complex, phenanthroline europium complex, and the like.

Examples of polymeric materials include polyparaphenylene vinylene or derivatives thereof, polythiophene or derivatives thereof, polyparaphenylene or derivatives thereof, polysilane or derivatives thereof, polyacetylene or derivatives thereof, polyfluorene or derivatives thereof, polyvinylcarbazole or derivatives thereof, Examples thereof include materials obtained by polymerizing at least one of the dye material and the metal complex material.

A dopant material is added, for example, to improve the luminous efficiency or change the luminous wavelength. Dopant materials mainly assisting organic substances that emit at least one of fluorescence and phosphorescence include, for example, perylene or its derivatives, coumarin or its derivatives, rubrene or its derivatives, quinacridone or its derivatives, squarium or its derivatives, porphyrin or its derivatives. , styryl dyes, tetracene or derivatives thereof, pyrazolones or derivatives thereof, decacyclene or derivatives thereof, phenoxazone or derivatives thereof, and the like.

The organic EL layer 14 may include various functional layers in addition to the light emitting layer 14a. Examples of the functional layer disposed between the transparent electrode 13, which is an anode, and the light-emitting layer 14a include the hole injection layer 14b and the hole transport layer 14c, as shown in FIG.

The hole injection layer 14b is a functional layer having a function of improving the efficiency of hole injection from the transparent electrode (anode) 13 to the light emitting layer 14a. The hole injection layer 14b may be an inorganic layer or an organic layer. The hole injection material forming the hole injection layer 14b may be a low-molecular compound or a high-molecular compound.

Examples of the hole injection material include metal oxides such as vanadium oxide, molybdenum oxide, ruthenium oxide, and aluminum oxide, and amorphous carbon. When the hole injection material is a low-molecular-weight compound, examples of the low-molecular-weight compound include phenylamine compounds, starburst-type amine compounds, and phthalocyanine compounds. Examples include amine compounds, starburst type amine compounds, and phthalocyanine compounds.

When the hole injection material is a polymer compound, examples of the polymer compound include polyaniline, polythiophene, polythiophene derivatives such as polyethylenedioxythiophene (PEDOT), polypyrrole, polyphenylene vinylene, polythienylene vinylene, polyquinoline and poly Examples include quinoxaline and derivatives thereof; and conductive polymers such as polymers containing an aromatic amine structure in the main chain or side chain.

The optimum thickness of the hole injection layer 14b varies depending on the material used. The thickness of the hole injection layer 14b can be appropriately determined in consideration of the required properties and the simplicity of film formation. The thickness of the hole injection layer 14b is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The hole-transporting layer 14c is a functional layer having a function of improving the efficiency of hole injection from the hole-injecting layer 14b (the transparent electrode (anode) 13 in a form in which the hole-injecting layer 14b does not exist) to the light-emitting layer 14a. .

Hole transport layer 14c is an organic layer containing a hole transport material. The hole-transporting material is not limited as long as it is an organic compound having a hole-transporting function. Examples of organic compounds having a hole transport function include polyvinylcarbazole or derivatives thereof, polysilane or derivatives thereof, polysiloxane derivatives having aromatic amine residues in side chains or main chains, pyrazoline derivatives, arylamine derivatives, and stilbene derivatives. , triphenyldiamine derivative, polyaniline or its derivative, polythiophene or its derivative, polypyrrole or its derivative, polyarylamine or its derivative, poly(p-phenylene vinylene) or its derivative, polyfluorene derivative, having an aromatic amine residue Polymer compounds, and poly(2,5-thienylenevinylene) or derivatives thereof.

Examples of hole transport materials include JP-A-63-70257, JP-A-63-175860, JP-A-2-135359, JP-A-2-135361, JP-A-2-209988, Also included are hole transport materials described in JP-A-3-37992 and JP-A-3-152184.

The optimum thickness of the hole transport layer 14c differs depending on the material used. The thickness of the hole-transporting layer 14c can be appropriately determined in consideration of the required properties, the simplicity of film formation, and the like. The thickness of the hole transport layer 14c is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The organic EL layer 14 may have an electron transport layer, an electron injection layer, etc. between the light emitting layer 14 a and the reflective electrode (cathode) 15 .

The electron transport layer is a functional layer that has the function of improving the efficiency of electron injection from the electron injection layer (the reflective electrode (cathode) 15 if the organic EL layer 14 does not have an electron injection layer) to the light emitting layer 14a.

The electron-transporting layer is an organic layer containing an electron-transporting material. A known material can be used as the electron transport material. Specific examples of electron transport materials include oxadiazole derivatives, anthraquinodimethane or derivatives thereof, benzoquinone or derivatives thereof, naphthoquinone or derivatives thereof, anthraquinone or derivatives thereof, tetracyanoanthraquinodimethane or derivatives thereof, fluorenone derivatives, Diphenyldicyanoethylene or its derivatives, diphenoquinone derivatives, metal complexes of 8-hydroxyquinoline or its derivatives, polyquinoline or its derivatives, polyquinoxaline or its derivatives, polyfluorenes or its derivatives, and the like.

The thickness of the electron-transporting layer can be appropriately determined in consideration of the required properties, ease of film formation, and the like. The thickness of the electron transport layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 5 nm to 200 nm.

The electron injection layer is a functional layer having a function of improving the electron injection efficiency from the reflective electrode (cathode) 15 to the light emitting layer 14a. When the organic EL layer 14 has an electron transport layer, the electron injection layer is arranged between the electron transport layer and the reflective electrode 15 . In this case, the electron transport layer injects electrons from the electron injection layer to the light emitting layer 14a. The electron injection layer may be an inorganic layer or an organic layer. The electron injection layer may be part of the reflective electrode 15 .

As the material forming the electron injection layer, an optimum material is appropriately selected according to the type of the light emitting layer 14a. Examples of materials constituting the electron injection layer include alkali metals, alkaline earth metals, alloys containing one or more of alkali metals and alkaline earth metals, oxides of alkali metals or alkaline earth metals, and halides. , carbonates, or mixtures of these substances. Examples of alkali metals, alkali metal oxides, halides and carbonates include lithium, sodium, potassium, rubidium, cesium, lithium oxide, lithium fluoride, sodium oxide, sodium fluoride, potassium oxide, potassium fluoride, Rubidium oxide, rubidium fluoride, cesium oxide, cesium fluoride, lithium carbonate, and the like may be mentioned. Examples of alkaline earth metals or alkaline earth metal oxides, halides and carbonates include magnesium, calcium, barium, strontium, magnesium oxide, magnesium fluoride, calcium oxide, calcium fluoride, barium oxide, fluoride Barium, strontium oxide, strontium fluoride, magnesium carbonate and the like.

In addition, a layer in which a conventionally known electron-transporting organic material and an organometallic complex of an alkali metal are mixed can be used as the electron injection layer.

The thickness of the electron injection layer is, for example, 1 nm to 1 μm, preferably 2 nm to 500 nm, more preferably 3 nm to 200 nm.

Examples of layer structures that the organic EL layer 14 can have are shown below. In the description of the layer structure of the organic EL layer 14, the transparent electrode 13 and the reflective electrode 15 are referred to as anodes in order to show the arrangement relationship between the anode (transparent electrode 13) and the cathode (reflective electrode 15) and the arrangement relationship among various functional layers. and the cathode. In the arrangement examples below, the anode and cathode are also listed in brackets.
(a) (anode)/hole injection layer/light-emitting layer/(cathode)
(b) (anode)/hole injection layer/light emitting layer/electron injection layer/(cathode)
(c) (Anode)/Hole Injection Layer (or Hole Transport Layer)/Emitting Layer/Electron Transport Layer/Electron Injection Layer/(Cathode)
(d) (anode)/hole injection layer/hole transport layer/light-emitting layer/(cathode)
(e) (Anode)/Hole Injection Layer/Hole Transport Layer/Emitting Layer/Electron Injection Layer/(Cathode)
(f) (Anode)/Hole Injection Layer/Hole Transport Layer/Emitting Layer/Electron Transport Layer/Electron Injection Layer/(Cathode)
(g) (anode)/light emitting layer/electron transport layer (or electron injection layer)/(cathode)
(i) (anode)/light emitting layer/electron transport layer/electron injection layer/(cathode)
The symbol "/" means that the layers on both sides of the symbol "/" are joined together.

The number of light-emitting layers 14a included in the organic EL layer 14 may be one, or two or more. In any one of the above layer configurations (a) to (i), the laminated structure arranged between the anode and the cathode is referred to as [structural unit I]. In this case, the structure of the organic EL layer 14 having two light-emitting layers 14a includes the layer structure shown in (j) below. The layer configurations of the two structural units I may be the same or different.
(j) (anode)/[structural unit I]/charge generating layer/[structural unit I]/(cathode)

The charge generation layer is a layer that generates holes and electrons by applying an electric field. Examples of the charge generation layer include thin films containing vanadium oxide, ITO, molybdenum oxide, and the like.

When "[structural unit I]/charge generation layer" is referred to as [structural unit II], the structure of the organic EL layer 14 having three or more light-emitting layers 14a includes the layer structure shown in (k) below. .
(k) (anode)/[structural unit II]x/[structural unit I]/(cathode)
The symbol "x" represents an integer of 2 or more, and "[structural unit II]x" represents a laminated structure in which [structural unit II] is laminated in x stages. A plurality of structural units II may have the same or different layer configurations.

The organic EL layer 14 may be configured by directly stacking a plurality of light emitting layers 14a without providing the charge generation layer.

The organic EL layer 14 can be formed by a coating method. Examples of coating methods include spin coating, inkjet printing, slit coating, micro gravure coating, gravure coating, bar coating, roll coating, wire bar coating, spray coating, screen printing, and flexographic coating. A printing method, an offset printing method, a reverse printing method, a nozzle printing method, and the like can be mentioned. The gravure coating method, screen printing method, flexographic printing method, offset printing method, reverse printing method, and inkjet printing method are preferable in that pattern formation and multicolor application are easy. When the organic EL layer 14 has a plurality of functional layers, each functional layer can be formed by a coating method.

A reflective electrode 15 is arranged on the organic EL layer 14 . The optimum thickness of the reflective electrode 15 differs depending on the material used, and is set in consideration of electrical conductivity, durability, and the like. The thickness of the reflective electrode 15 is usually 10 nm to 10 μm, preferably 20 nm to 1 μm, more preferably 50 nm to 500 nm.

The material of the reflective electrode 15 is selected from the organic EL layer 14 so that the light from the organic EL layer 14 (specifically, the light from the light-emitting layer 14a) is reflected by the reflective electrode 15 and travels toward the transparent electrode 13. A material having a high reflectance with respect to the light (especially visible light) emitted from the light emitting layer 14a is preferable. Materials for the reflective electrode 15 include, for example, alkali metals, alkaline earth metals, transition metals, and metals containing Group 13 elements of the periodic table. A transparent conductive electrode containing a conductive metal oxide, a conductive organic substance, or the like may be used as the reflective electrode 15 . The reflective electrode 15 may have multiple layers.

The reflective electrode 15 can be formed by a dry film forming method, a coating method, or the like. Examples of the dry film forming method and the coating method are as described above.

[Light extraction layer]
Next, the light extraction layer 12 will be described. The light extraction layer 12 is arranged on the optical path of the light emitted from the light emitting layer 14a. In the form shown in FIG. 1, the light extraction layer 12 is arranged between the transparent substrate 11 and the transparent electrode 13 . The light extraction layer 12 has a light scattering layer 12 a including a base material 121 (or base material layer) and scattering particles 122 dispersed in the base material 121 . The light extraction layer 12 may have a planarization layer 12b as shown in FIG.

An example of the material of the base material 121 is transparent resin. The transmission parameter K of the transparent resin forming the base material 121 is 4.0×10 ⁻² cm/h ^0.5 or less (4.0×10 ⁻⁴ m/h ^0.5 or less). An example of the transparent resin used for the base material 121 is not particularly limited as long as it satisfies the condition of the transmission parameter K and is transparent to the light emitted from the light emitting layer. Thermoplastic, thermosetting, light (electromagnetic wave) curing by visible light, ultraviolet rays, infrared rays, or the like, and electron beam curing by electron beam irradiation are preferably used. The transmission parameter K can be adjusted by changing the material, composition, etc. of the resin.

Examples of such resins include polycarbonate (PC), polystyrene (PS), polyether, polyester, polyarylate, polyamide, polyimide, phenol-formaldehyde resin (phenolic resin), polydiethylene glycol bisallyl carbonate, acrylonitrile-styrene co- Polymers (AS resins), methyl methacrylate/styrene copolymers (MS resins), poly-4-methylpentene, norbornene-based polymers, urethane resins, epoxy resins, oxetane resins, acrylic resins, silicone resins, and the like. In addition, an organic-inorganic nanocomposite in which an organic polymer matrix and highly refractive inorganic nanoparticles are combined can also be used, but the present invention is not necessarily limited to these. These can be used singly or as a mixture of two or more at any ratio as required.

The compound constituting the photocurable resin may have two or more polymerizable functional groups per molecule. When the photocurable resin is composed of a compound having two or more polymerizable functional groups, it is possible to obtain a dense coating layer with a high crosslink density, which effectively suppresses permeation of moisture in the coating layer. This can contribute to improving the storage durability of the organic EL device 10 . The compound having two or more polymerizable functional groups is not particularly limited. It may be a compound having two or more kinds of polymerizable functional groups in one molecule, if necessary.

If necessary, nanoparticles may be added to the transparent resin used for the base material 121 in order to improve the refractive index. Examples of nanoparticles include zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), hafnium oxide (HfO ₂ ), Tantalum pentoxide (Ta ₂ O ₅ ) and the like are included. An example of the particle size of the nanoparticles is 0.001 μm or more and 0.05 μm or less. An example of the refractive index of the base material 121 (including the base material 121 in which nanoparticles are dispersed) is 1.6 or more and 2.0 or less. The refractive index of the base material 121 is preferably 1.7 or higher. The refractive index at a wavelength of 589 nm (D-line wavelength) is taken as the refractive index of the base material 121, and can be measured with a multi-wavelength Abbe refractometer, prism coupler, spectral interferometer, spectral ellipsometer, or the like.

The scattering particles 122 are particles for scattering light generated within the organic EL device 10 . The scattering particles 122 include titanium oxide (TiO ₂ ), zirconium oxide (ZrO ₂ ), titanium oxide (TiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zinc oxide (ZnO), tin oxide (SnO ₂ ), oxide hafnium ₍ HfO2), tantalum pentoxide ₍ Ta2O5), calcium oxide ₍ CaO), calcium carbonate ( _CaCO3 ), barium oxide (BaO), barium carbonate (BaCO3) _, barium titanate (BaTiO3) _, etc. and organic particles such as polymethyl methacrylate beads, acrylic-styrene copolymer beads, melamine resin beads, polycarbonate beads, polystyrene beads, cross-linked polystyrene beads, polyvinyl chloride beads, and benzoguanamine-melamine formaldehyde condensate beads. mentioned.

The particle diameter of the scattering particles 122 is larger than the particle diameter of the nanoparticles. An example of the particle diameter of the scattering particles 122 is 0.1 μm or more and 10 μm or less.

Since the scattering particles 122 scatter light, the refractive index of the scattering particles 122 is different from the refractive index of the base material 121 . Examples of the refractive index of the scattering particles 122 may be 2.0 or more and 2.4 or less, or 1.3 or more and 1.5 or less. The difference between the refractive index of the scattering particles 122 and the refractive index of the base material 121 can be 0.3 or more. An example of the upper limit of the difference between the refractive index of the scattering particles 122 and the base material 121 is 0.8. The refractive index of the scattering particles 122 is the refractive index at a wavelength of 589 nm (D-line wavelength) and can be measured by a multi-wavelength Abbe refractometer, prism coupler, spectroscopic interferometer, spectroscopic ellipsometer, or the like. Values from various databases can be used for materials such as inorganic particles that are difficult to measure the refractive index. The particle size of the scattering particles 122 dispersed in the base material 121 may be different. That is, scattering particles 122 having different particle diameters may be dispersed in the base material 121 .

An example of the thickness of the light scattering layer 12a is 0.3 μm or more and 10 μm or less. The thickness of the light scattering layer 12a can be the in-plane average thickness in the plane orthogonal to the thickness direction of the light scattering layer 12a. The light scattering layer 12a can be measured with a thickness gauge. An example of the volume concentration of the scattering particles 122 is 5 vol % or more and 80 vol % or less.

The light scattering layer 12a can be formed by a coating method. Examples of coating methods are described above.

The planarization layer 12b is a layer for reducing unevenness of the surface caused by the scattering particles 122 of the light scattering layer 12a. The material of the flattening layer 12b can be a material that does not cause a refractive index difference with the base material 121 of the light scattering layer 12a. In one embodiment, the planarization layer 12b is made of the same material as the base material 121 described above. An example of the thickness of the planarization layer 12b is 0.5 μm or more and 10 μm or less. The planarizing layer 12b can be formed by a coating method. Examples of coating methods are described above.

The light extraction layer 12 may satisfy the following condition (A).
Condition (A):
As shown in FIG. 2, a first layer 41 having the same structure as the light scattering layer 12a is formed on the transparent substrate 11 by a coating method, and a second layer 42 having the same structure as the flattening layer 12b is applied. The first hue b ^* (hereinafter referred to as “b ^* _1”) of the laminate 40 obtained by forming the laminate 40 by the method and the temperature of the laminate 40 after degassing the laminate 40 is 230° C.±5 The difference Δb ^* in the second hue b ^* (hereinafter referred to as “b ^* — 2”) of the laminate 40 after the laminate 40 is heat-treated for 15 minutes ± 10 seconds so that the temperature reaches °C is 5 or less. be. The difference Δb ^* is defined by the following formula (I).
Δb ^* =(b ^* _2)-(b ^* _1) (I)

The hue b ^* is a transmission hue, and an example of b ^* _1 is 0.0 or more and 15.0 or less. An example lower limit for Δb ^* is 0.5.

Since the first layer 41 has the same configuration as the light scattering layer 12a, it has a base material 121 and scattering particles 122 as shown in FIG. The material of the base material 121 and the scattering particles 122 of the first layer 41 are the same as those of the light scattering layer 12a. The volume concentration of the scattering particles 122 in the first layer 41 is also the same as in the light scattering layer 12a. The thickness of the first layer 41 is also the same as that of the light scattering layer 12a. Since the second layer 42 has the same configuration as the planarization layer 12b, the material and thickness of the second layer 42 are the same as those of the planarization layer 12b.

An example of the temperature included in the above heating conditions is the maximum process temperature among the process temperatures when forming the device main body composed of the transparent electrode 13, the organic EL layer 14, and the reflective electrode 15 in the manufacture of the organic EL device 10. The heating time included in the heating conditions corresponds to the time during which the light extraction layer 12 is heated at the maximum process temperature. The temperature and time under the above heating conditions are, for example, a temperature of 230° C. and 15 minutes.

As shown in FIG. 1, organic EL device 10 may have barrier layer 16 between light extraction layer 12 and transparent electrode 13 .

A barrier layer 16 is disposed on the light extraction layer 12 . A barrier layer 16 is located between the light extraction layer 12 and the transparent electrode 13 . An example of barrier layer 16 is an inorganic thin film layer. An example of the water vapor permeability of the barrier layer 16 is 1×10 ⁻¹ g/(m ² ·day) or less. The water vapor transmission rate can be a value calculated by a calcium corrosion method (method described in Japanese Patent Application Laid-Open No. 2005-283561) under conditions of a temperature of 40° C. and a humidity of 90% RH.

The barrier layer 16 has a refractive index equal to or higher than that of the base material 121, for example. An example of the refractive index of the barrier layer 16 is 1.8 or more and 2.4 or less. As a material for the barrier layer 16, a layer of an inorganic material having a known gas barrier property can be appropriately used from the viewpoint of refractive index and transparency. Examples of inorganic materials include metal oxides, metal nitrides, metal oxynitrides, metal oxycarbides, and mixtures comprising at least two of these. Moreover, a multilayer film in which two or more layers of the thin film layers described above are laminated can also be used. In addition, inorganic polymeric materials such as perhydropolysilazanes can also be used. An example thickness of the barrier layer 16 is 10 nm or more and 1000 nm or less.

The barrier layer 16 can be formed by a dry film-forming method, a coating method, or the like. Examples of the dry film forming method and the coating method are as described above.

In the organic EL device 10, the water vapor permeability of the transparent substrate 11 is preferably lower than the water vapor permeability of the barrier layer 16, and the water vapor permeability of the transparent substrate 11 is more than 1/10 of the water vapor permeability of the barrier layer 16. Smaller is more preferred. That is, when the water vapor permeability of the transparent substrate 11 is α (g/(m ² ·day)) and the water vapor permeability of the barrier layer 16 is β (g/(m ² ·day)), the formula (8a) is preferably satisfied, and more preferably formula (8b) is satisfied.
α<β (8a)
α<β/10 (8b)

Organic EL device 10 can be manufactured, for example, by forming light extraction layer 12 , transparent electrode 13 , organic EL layer 14 and reflective electrode 15 on transparent substrate 11 in this order. If the organic EL device 10 has the barrier layer 16 , the barrier layer 16 may be formed after forming the light extraction layer 12 and before forming the transparent electrode 13 .

The organic EL device 10 may include a sealing member that seals the organic EL layer 14 . The sealing member is not particularly limited as long as it suppresses deterioration of the organic EL device 10 due to moisture, oxygen, etc., entering from the outside. There is a stop member. In this embodiment, an organic EL device 10 having a sheet-like (or layered) sealing member will be described. FIG. 3 is a drawing for explaining an example of an organic EL device with a sealing member. The organic EL device 10 shown in FIG. 3 is called an organic EL device 10A.

As shown in FIG. 3, the organic EL device 10A includes a transparent substrate 11, a light extraction layer 12, a transparent electrode 13, an organic EL layer 14, a reflective electrode 15, an auxiliary electrode 31, and a sealing member 51. and a reflective layer 52 . Although omitted in FIG. 3, the organic EL device 10A may include a barrier layer 16 between the light extraction layer 12 and the transparent electrode 13, as in the case of the organic EL device 10. FIG.

For the convenience of the following description, the portions of the organic EL device 10A other than the sealing member 51 and the reflective layer 52, that is, the light extraction layer 12, the barrier layer 16, the transparent electrode 13, the auxiliary electrode 31, and the organic EL layer 14 And the transparent substrate 11 on which the reflective electrode 15 is formed is called a device substrate 30 .

The configuration and arrangement relationship of the transparent substrate 11 and the light extraction layer 12 are the same as in the case of the organic EL device 10, so description thereof will be omitted.

The transparent electrode 13 and the auxiliary electrode 31 are spaced apart on the light extraction layer 12 (on the barrier layer 16 when the organic EL device 10A has the barrier layer 16). Since the configuration of the transparent electrode 13 is the same as that of the organic EL device 10, the description thereof is omitted.

The auxiliary electrode 31 is electrically connected to the reflective electrode 15 . An external terminal is connected to the auxiliary electrode 31 . The auxiliary electrode 31 is an electrode for supplying electric power to the reflective electrode 15 arranged inside the sealing member 51, as shown in FIG.

The thickness and material of the auxiliary electrode 31 may be the same as those of the transparent electrode 13 . In this case, the auxiliary electrode 31 and the transparent electrode 13 are formed by forming an electrode layer using the same material as those, and then patterning the transparent electrode 13 and the auxiliary electrode 31 by finely processing the electrode layer. can be formed. The auxiliary electrode 31 may be made of a conductive material different from that of the transparent electrode 13 . The auxiliary electrode 31 may be formed so as to be separated from the transparent electrode 13 in advance when the transparent electrode 13 is formed. That is, the transparent electrode 13 and the auxiliary electrode 31 may be individually formed without patterning one electrode layer as described above. The auxiliary electrode 31 may be formed before or after forming the transparent electrode 13 .

The configurations of the organic EL layer 14 and the reflective electrode 15 are the same as those of the organic EL device 10 . In the organic EL device 10A, the organic EL layer 14 can also be arranged between the transparent electrode 13 and the auxiliary electrode 31. FIG. In the organic EL device 10A, the reflective electrode 15 is formed on the organic EL layer 14 as in the case of the organic EL device 10 and is also formed on the auxiliary electrode 31 . Thereby, the reflective electrode 15 and the auxiliary electrode 31 are electrically connected.

The sealing member 51 is a sheet-like (or layered) sealing member. The sealing member 51 has a sealing function of blocking permeation of moisture from the edge and an adhesive function of bonding the reflective layer 52 having sealing ability and reflectivity to the device substrate 30 . The sealing member 51 having such a function can be formed of a known adhesive (including the concept of pressure sensitive adhesive) having a sealing ability that can be used in organic EL devices.

The reflective layer 52 is arranged on the sealing member 51 . The size of the reflective layer 52 is such that when the organic EL device 10A is viewed from above (when viewed from the thickness direction), the light emitting portion (the transparent electrode 13, the organic EL layer 14, and the reflective electrode 15 are overlapped with each other) of the organic EL device 10A. area) is preferably larger. As a result, more light generated in the organic EL device 10A can be output from the transparent substrate 11 side.

As the reflective layer 52, a metal thin film formed of silver, aluminum, platinum, nickel, tin, copper, rhodium, chromium, lead, palladium, molybdenum, tungsten, gold, or the like, or any of the above-exemplified metals. An alloy thin film formed by an alloy of at least two kinds of metals can be used. In addition, a protective layer may be used in order to prevent deterioration of reflectivity due to oxidation of the metal thin film (or alloy thin film) used as the reflective layer 52 . The reflective layer 52 such as the metal thin film is formed on a supporting member (substrate, film, etc.), and the supporting member preferably has barrier properties. By doing so, it is possible to prevent moisture and oxygen from entering the organic EL device 10A from the external environment, thereby preventing deterioration of the organic EL device 10A. The support member may also be part of the reflective member.

For convenience of explanation, the sealing member 51 having the reflective layer 52 formed thereon may also be referred to as a sealing member 50 .

The sealing member 50 (or sealing member 51 ) is bonded to the device substrate 30 such that the transparent electrode 13 and the auxiliary electrode 31 are partly located outside the sealing member 50 . Thereby, power can be supplied to the transparent electrode 13 and the auxiliary electrode 31 .

Organic EL device 10A can be manufactured, for example, as follows. A device substrate 30 is manufactured in the same manner as the organic EL device 10 except that the auxiliary electrode 31 is formed as described above. The sealing member 50 is obtained by forming the reflective layer 52 on the sealing member 51 or by bonding the sealing member 51 to the reflective layer 52 . The reflective layer 52 depends on the material that constitutes the reflective layer 52, but can be formed by vacuum deposition, for example. After that, the sealing member 50 is joined to the device substrate 30 so that the transparent electrode 13 and part of the auxiliary electrode 31 are located outside the sealing member 50 . The organic EL device 10A is thus obtained.

Actions and effects of the organic EL devices 10 and 10A will be described. The organic EL device 10A has a configuration similar to that of the organic EL device 10 as a basic configuration. Therefore, since the organic EL device 10A has the same operational effects as the organic EL device 10, the operational effects of the organic EL devices 10 and 10A will be described for the organic EL device 10 unless otherwise specified.

In the organic EL device 10 , when power is supplied to the transparent electrode 13 and the reflective electrode 15 , light is generated in the light emitting layer 14 a within the organic EL layer 14 . The light generated in the light emitting layer 14a passes through the transparent electrode 13 and is output from the transparent substrate 11 side. Of the light generated in the light emitting layer 14a, the light traveling toward the reflective electrode 15 is reflected by the reflective electrode 15 and then output from the transparent substrate 11 side.

The organic EL device 10 has the light extraction layer 12 on the optical path of the light emitted from the light emitting layer 14a. The light incident on the light extraction layer 12 after being emitted from the light emitting layer 14 a is scattered by the scattering particles 122 in the light scattering layer 12 a of the light extraction layer 12 . Therefore, light confinement due to total reflection inside the transparent electrode 13, the transparent substrate 11, etc. is suppressed, so that the light extraction efficiency is improved.

The transmission parameter K of the resin contained in the light scattering layer 12a of the light extraction layer 12 (specifically, the resin contained in the base material 121) is 4.0×10 ⁻² cm/h ^0.5 or less (4. 0×10 ⁻⁴ m/h ^0.5 or less). Therefore, in the organic EL device 10, improvement in storage durability can be realized while realizing improvement in light extraction efficiency. The improved storage durability allows the organic EL device 10 to be stably driven for a longer period of time.

When the organic EL device 10 has the barrier layer 16, it is possible to prevent moisture from entering the organic EL layer 14 from the transparent substrate 11 side. Therefore, the product life of the organic EL device 10 is improved. When the water vapor permeability of the transparent substrate 11 and the barrier layer 16 satisfies the above formula (8a) (more preferably satisfies the formula (8b)), it is possible to prevent moisture from entering the organic EL layer 14 from the transparent substrate 11 side. It can be prevented further.

When the light extraction layer 12 satisfies the above condition (A), a higher light extraction efficiency can be achieved, and the water vapor permeability of the transparent substrate 11 and the barrier layer 16 must satisfy the above formula (8a) ( More preferably, by satisfying formula (8b), it is possible to stably drive the organic EL device 10 for a long period of time.

Next, an experimental example will be described. The present invention is not limited to the experimental examples described below. For convenience of explanation, elements corresponding to the elements described in the above embodiment are denoted by the same reference numerals in the description of the experimental example.

<Measurement and evaluation method>
Methods for measuring or evaluating physical quantities used in experimental examples will be described.

(Method for measuring refractive index)
The refractive index was determined by analyzing the optical constants of the absolute reflectance measurement results obtained with a reflection spectroscopic film thickness meter (manufactured by Otsuka Electronics Co., Ltd., FE-3000).

(Method for measuring film thickness)
A stylus-type film thickness measuring device (P-16, manufactured by KLA-Tencor) was used for the film thickness measurement.

(Method for measuring total light transmittance and haze)
Total light transmittance and haze were measured using a haze meter (manufactured by Suga Test Instruments Co., Ltd., HZ-V3), using air as a blank and a C light source as a light source, according to JISK7105.

(Measurement of b ^* of light extraction layer)
The hue b ^* of the light extraction layer was measured using a spectrophotometer (CM-3600A, manufactured by Konica Minolta Co., Ltd.), using air as a blank, and allowing light to enter from the light extraction layer side, in accordance with ASTM D1925 (C light source). It was measured.

(Measurement of water vapor permeability)
The gas barrier properties of laminated films having barrier properties were evaluated by water vapor transmission rate (WVTR). The water vapor transmission rate was calculated by the calcium corrosion method (method described in Japanese Patent Application Laid-Open No. 2005-283561) under conditions of a temperature of 40° C. and a humidity of 90% RH. That is, after the laminated film is dried, metallic calcium is vapor-deposited, then metallic aluminum is vapor-deposited thereon, and finally, glass is bonded using a sealing resin to bond the sample. The increase in corrosion points on the laminated film side due to changes over time under the conditions of 40° C. and 90% RH was examined by image analysis to calculate the water vapor transmission rate.

In addition, when calculating such a water vapor transmission rate, the corrosion point is photographed with a microscope, the image is taken into a personal computer, the image of the corrosion point is binarized, and the corrosion area is calculated and obtained. Water vapor permeability was calculated. The smaller the water vapor transmission rate, the better the gas barrier properties.

(Calculation of transmission parameter K)
The permeation parameter K was calculated by the method described below under conditions of a temperature of 60° C. and a humidity of 90% RH.

That is, as shown in FIG. 4A, calcium (Ca) is deposited on the center of a glass substrate 60 (manufactured by Corning, EagleXG) having a substrate size of 50 mm×50 mm and a thickness of 0.7 mm by a vacuum deposition method. A metal calcium film 61 having a size of 25 mm×25 mm and a film thickness of 100 nm was obtained by vapor deposition.

After vapor deposition, the glass substrate 60 was transported from the vapor deposition chamber to the sealing treatment chamber without being exposed to the atmosphere, and in a nitrogen atmosphere (inert atmosphere), as shown in FIG. A resin 62 to be measured was dropped on 61 . Next, as shown in FIG. 4C, a sealing glass substrate 63 (manufactured by Corning Incorporated, manufactured by Corning, Inc.) having a substrate size of 37 mm×40 mm and a thickness of 0.7 mm is placed on the resin layer 62a formed of the dropped resin 62. Eagle XG) was applied so that one side of the edge of the sealing glass substrate 63 was parallel to the vapor-deposited metallic calcium film 61 and the distance from the vapor-deposited edge of the metallic calcium film 61 was about 2 mm, and air bubbles were formed in the resin layer 62a. The measurement sample S shown in FIG. 4(d) and FIG.

When preparing the measurement sample S as described above, in order to make the thickness of the resin layer 62a uniform in the plane, after the step of FIG. 4(a), as shown in FIG. A PET film 64 (Lumirror #12-S10, 12 μm thick, manufactured by Toray Industries, Inc.) cut to a size of 7 mm×7 mm was placed at four points on the edge of the glass substrate 60 . As shown in FIGS. 4(c) and 4(d), when installing the sealing glass substrate 63, the sealing glass substrate 63 is arranged so as to ride on a portion of the PET film 64 (approximately 2 mm wide). did.

In preparation of the measurement sample S, the resin 62 protruding from the sealing glass substrate 63 is wiped off with a rag before hardening, so that the excess resin 62 does not exist at the edge of the sealing glass substrate 63, thereby reducing the resin layer 62a. The distance between the end and the end of the sealing glass substrate 63 can be the same as the end of the metal calcium film 61 (the end of metal calcium deposition). The resin 62 was stored in a nitrogen atmosphere (inert atmosphere) with a dew point of 70° C. or less for one day or longer and dehydrated in advance.

In the experimental example, the resin was in the form of droplets, but when the resin to be measured is in the form of a sheet, a substrate such as metal foil or thin plate glass that is flexible and impermeable to moisture can be used. After laminating a resin sheet to , a dehydration treatment is performed, and a glass substrate 60 on which calcium is vapor-deposited is laminated in the same arrangement as the sealing glass substrate 63 so as not to contain air bubbles, thereby obtaining a measurement sample. can be obtained.

Next, the measurement sample S is placed in a thermo-hygrostat at 60° C. and 90% RH, and the distance x between the edge of the resin layer 62a and the edge of the metal calcium film 61 used for the above-described measurement is measured at regular time intervals. Measurement was performed three times with a microscope, and the average value was used for calculation of the transmission parameter K. The predetermined time is 25 hours from the start of the test until 100 hours have passed, and is 100 hours after 100 hours have passed. The test was terminated when 1000 hours had elapsed from the start of the test or when the distance xt between the end of the resin layer 62a and the end of the metallic calcium film 61 reached 5 mm or more due to permeation of moisture, and K _{=xt .} The permeation parameter K was calculated using the relational expression of /t ^1/2 (equation (7a) above). t in formula (7a) was the time from the start of the test to the end of the test.

(Method for measuring sheet resistance)
Sheet resistance was measured by a four-terminal, four-probe method (Mitsubishi Chemical Analytic Tech Loresta GP).

(Adjustment of photocurable resin compound)
According to the composition shown in FIG. 6, each component was mixed to prepare a photocurable resin compound. “%” in FIG. 6 represents “mass %”. A transmission parameter K was calculated for the adjusted photocurable resin compound. Experimental Examples 1 to 5 in FIG. 6 correspond to Experimental Examples 1 to 5 in FIG.

Each component shown in FIG. 6 is shown below.
<Alicyclic epoxy compound having two or more polymerizable functional groups>
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexane carboxylate (“Celoxide 2021P” (trade name), manufactured by Daicel Chemical Industries, Ltd.)
<Aliphatic Epoxy Compound Having Two or More Polymerizable Functional Groups>
Pentaerythritol polyglycidyl ether (“EX-411” (trade name), manufactured by Nagase ChemteX Co., Ltd.)
<Aromatic epoxy compound having two or more polymerizable functional groups>
2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl]ethyl]phenyl]propane (“TECHMORE VG3101L ” (trade name), manufactured by Printec Co., Ltd.)
<Oxetane compound (A) having two or more polymerizable functional groups>
Bis (3-ethyl-3-oxetanylmethyl) ether (“OXT-221” (trade name), manufactured by Toagosei Co., Ltd.)
<Oxetane compound (B) having one polymerizable functional group>
2-ethylhexyloxetane (“OXT-212” (trade name), manufactured by Toagosei Co., Ltd.)
<Polymerization initiator>
Photocationic polymerization initiator: propylene carbonate 50 solution of triarylsulfonium hexafluorophosphate (“CPI-100P” (trade name), manufactured by San-Apro Co., Ltd.)
<Leveling material>
Silicone leveling agent (“SH710” (trade name), manufactured by Dow Corning Toray Co., Ltd.)

<Manufacture of organic EL device>
Next, a method for manufacturing the organic EL device used in the experimental examples will be described. In an experimental example, an organic EL device 10A having a sealing member 50 was manufactured as shown in FIG. In experimental examples, as shown in FIGS. 6 and 7, organic EL devices 10A of Examples 1 to 5 were manufactured under different conditions. A method for manufacturing the organic EL device 10A will be specifically described for Experimental Example 1. FIG.

(1) Experimental example 1
(Preparation of light extraction layer)
A dispersion of zirconium oxide (ZrO ₂ ) having an average primary particle size of 5 nm was mixed and added into a photocurable resin compound prepared according to the composition for Experimental Example 1 shown in FIG. 6 to obtain a base material dispersion solution. rice field. The transmission parameter K of the photocurable resin compound used in the base material dispersion solution was employed as the transmission parameter K of the resin forming the light scattering layer 12a of Example 1. The transmission parameter K of the resin forming the light scattering layer 12a in Example 1 was as shown in FIG.

The obtained base material dispersion solution was coated on a glass substrate (EagleXG manufactured by Corning) by a spin coating method under the conditions of a slope of 1 second, a number of revolutions of 1000 rpm, and a holding time of 30 seconds. dried for a minute. After drying, the coating layer was subjected to a curing treatment using a UV irradiation device (SP-9, manufactured by Ushio Inc.) under the conditions of an illuminance of 30 mW/cm ² and an integrated light intensity of 800 mJ/cm ² to remove the base material coating layer. Obtained. The base material coating layer corresponds to the base material 121 shown in FIG. The refractive index was measured using the obtained base material coating layer.

Titanium oxide (TiO ₂ , manufactured by Tayca, JR600E) having a refractive index of 2.4 and an average particle diameter of 0.27 μm was used for the scattering particles 122 . PGME (propylene glycol monomethyl ether) was added as a dispersion medium to the scattering particles 122 and subjected to dispersion treatment to obtain a silicon oxide particle dispersion. Thereafter, the photocurable resin compound and zirconium oxide in the base material dispersion solution are mixed so that the solid content concentration of titanium oxide in the titanium oxide particle dispersion solution is 15 vol %, and coating for forming a light scattering layer is performed. I got the liquid.

(Preparation of transparent substrate)
As the transparent substrate 11, a glass substrate (EagleXG manufactured by Corning Inc.) having a substrate size of 24 mm×24 mm and a thickness of 0.7 mm and subjected to pretreatment was used. The above pretreatment was carried out as follows.
<Pretreatment>
After cleaning the glass substrate with a brush scrubbing, two-fluid cleaning, rinsing with pure water, drying with an air knife, and further cleaning for 10 minutes using a UV ozone cleaning device (manufactured by Technovision Co., Ltd., trade name: UV-312). A surface modification treatment was performed.

(Formation of light scattering layer)
Next, the coating solution for forming a light scattering layer was dropped onto the transparent substrate 11 placed on the coater head of a spin coater, spin-coated, and then dried on a hot plate at 90° C. for 2 minutes. The film thickness was adjusted to 750 nm by changing the rotational speed of the spin coater. After drying, the coating layer was subjected to a curing treatment using a UV irradiation device (SP-9, manufactured by Ushio Inc.) under the conditions of an illuminance of 30 mW/cm ² and an integrated light intensity of 800 mJ/cm ² .

<Formation of planarization layer>
Furthermore, after coating the base material dispersion solution on the substrate with the light scattering layer by spin coating while adjusting the number of rotations of the spin coater so that the film thickness becomes 1500 nm, it is dried on a hot plate at 90° C. for 2 minutes. rice field. After drying, the coating layer (corresponding to the flattening layer 12b in FIG. 1) was subjected to the conditions of an illuminance of 30 mW/cm ² and an integrated light amount of 800 mJ/cm ² using a UV irradiation device (manufactured by Ushio Inc., SP-9). A hardening treatment was performed with and a flattening treatment was performed. In addition, degassing was performed on a hot plate at 200° C. for 10 minutes. As a result, the light extraction layer 12 having the light scattering layer 12a and the flattening layer 12b laminated on the light scattering layer 12a was formed, and as a result, the substrate with the light extraction layer was obtained.

In the process of obtaining the substrate with the light extraction layer, the substrate with the light extraction layer after the planarization treatment and before the degassing treatment (the coating layer and the light scattering layer after the planarization treatment and before the degassing treatment) A measurement of the hue b ^* of the substrate) was performed. The measurement result was adopted as the first hue b ^* _1 of the laminate 40 before heat treatment under the condition (A) described with reference to FIG. Separately from the substrate with the light extraction layer used for the measurement of the first hue b ^* , a substrate with the light extraction layer prepared by the same procedure as the substrate with the light extraction layer used for the measurement of the first hue b ^* was transparent. After heating for 15 minutes at the maximum temperature of 230° C. in the manufacturing process of the organic EL device 10A after the formation of the electrode 13 (the manufacturing process of the device main body), the hue b ^* was measured. The measurement result was adopted as the second hue b ^* _2 of the laminate 40 after heat treatment under the condition (A) described with reference to FIG. Using the first hue b ^* _1 and the second hue b ^* _2, the difference Δb ^* between the first hue b ^* _1 and the second hue b ^* _2 was calculated. The calculation results were as shown in FIG.

(Formation of barrier layer (inorganic thin film layer))
A barrier layer 16 was formed on the planarizing layer 12b of the substrate with the light extraction layer using a plasma CVD apparatus. Specifically, after loading the substrate with the light extraction layer into the discharge chamber of the plasma CVD device, the chamber was evacuated to 1×10 ⁻³ Pa or less. Then, SiH ₄ , N ₂ , and NH ₃ gases were introduced into the discharge chamber, and under the condition that the pressure was adjusted to 1.0 Pa, a high-frequency power of 13.56 kHz was applied to the induction coil, whereby the dielectric window was opened. plasma was generated in the chamber to form a silicon oxynitride film layer (barrier layer 16). The refractive index of the silicon oxynitride film layer at a wavelength of 200 nm and a wavelength of 589 nm was 1.87. Therefore, the obtained silicon oxynitride film layer (barrier layer 16) was a high refractive index barrier layer. At the same time, the water vapor transmission rate of the laminated film with the silicon oxynitride film formed on the COP film (Zeonor film ZF16, 50 μm thick, manufactured by Nippon Zeon Co., Ltd.) placed in the chamber was measured and found to be 5 × 10 ^-3 g. /(m ² ·day). The water vapor transmission rate of the laminate film with the silicon oxynitride film was measured by the method described in the evaluation method for gas barrier property described above.

(Formation of transparent electrode and auxiliary electrode)
Next, an ITO (In ₂ O ₃ —SnO ₂ ) film was formed on the barrier layer 16 of the substrate with the light extraction layer by sputtering using a metal shadow mask so as to have a thickness of 45 nm. A film was patterned to form an electrode 31 . The sheet resistance of the obtained ITO was 39Ω/□. The resulting transparent electrode-attached substrate was ultrasonically cleaned with an organic solvent, an alkaline detergent and ultrapure water in this order, then boiled in an organic solvent for 10 minutes and dried. Then, the surface on which the ITO thin film was formed was subjected to surface modification treatment for 10 minutes using a UV ozone cleaning device (manufactured by Technovision Co., Ltd., trade name: UV-312).

(Formation of organic EL layer)
<Hole injection layer>
A coating film having a thickness of 35 nm was formed by applying a hole injection material, which is a combination of an organic material having a charge-transporting property and an electron-accepting material, onto a substrate with a transparent electrode by a spin coating method. The coating film was dried on a hot plate in the atmosphere to form the hole injection layer 14b. In drying using a hot plate, drying was first performed at 80° C. for 4 minutes, and then further dried at 230° C. for 15 minutes.

<Hole transport layer>
A hole-transporting material, which is a polymer material, and xylene were mixed to obtain a composition for forming a hole-transporting layer having a solid matter (hole-transporting material) concentration of 0.7% by mass. The obtained composition for forming a hole transport layer was applied onto the hole injection layer 14b by a spin coating method to obtain a coating film having a thickness of 20 nm. The substrate provided with this coating film is placed in a nitrogen atmosphere (inert atmosphere), using a hot plate, heated at 200 ° C. for 30 minutes to evaporate the solvent, and then naturally cooled to room temperature to transport holes. Layer 14c was obtained.

<Light emitting layer>
The light-emitting conjugated polymer material and xylene were mixed to obtain a composition for forming a light-emitting layer in which the concentration of the light-emitting conjugated polymer material was 1.3%. A green light-emitting conjugated polymer material was used as the light-emitting conjugated polymer material. The obtained composition for forming a light emitting layer was applied onto the hole transport layer 14c by a spin coating method to obtain a coating film having a thickness of 60 nm. The substrate provided with this coating film is placed in a nitrogen atmosphere (inert atmosphere), using a hot plate, heated at 180° C. for 10 minutes to evaporate the solvent, and then naturally cooled to room temperature to obtain the light-emitting layer 14a. got

(reflective electrode)
After forming the light-emitting layer 14a, the reflective electrode 15 was formed in a vapor deposition chamber dedicated to metal. Specifically, on the light-emitting layer 14a, sodium fluoride (NaF) is vapor-deposited to a thickness of 3 nm by a vacuum vapor deposition method, and then aluminum (Al) is vapor-deposited to a thickness of 100 nm. , a reflective electrode 15 was formed. Thus, a device substrate 30 was obtained.

(sealing)
A barrier film was obtained by the manufacturing method disclosed in Example 1 of Japanese Patent No. 6691803. The barrier film was a laminated film in which a gas barrier layer and an inorganic polymer layer were laminated on a resin substrate. A film of silver (Ag) was formed to a thickness of 200 nm on the barrier surface (inorganic polymer layer) side of the barrier film by a vacuum deposition method to form a reflective layer 52 . The resulting reflective layer 52 had an average reflectance of 96.5% from 400 to 800 nm.

Next, a commercially available sealing adhesive sheet was pasted as a sealing member 51 onto the reflective layer 52 of the barrier film on which the reflective layer 52 was formed. As a result, the sealing member 50 in which the reflective layer 52 was provided on the sealing member 51 was obtained. The average reflectance of the sealing member 50 at wavelengths of 400 nm to 800 nm was 89.5%.

The device substrate 30 is transported from the deposition chamber to the sealing processing chamber without being exposed to the atmosphere, and the sealing member 50 and the device substrate 30 transported from the deposition chamber are bonded under a nitrogen atmosphere (inert atmosphere). Together, the device substrate 30 was sealed with the sealing member 50 . This completes the organic EL device 40A.

(2) Manufacture of organic EL devices of Experimental Examples 2, 4, and 5 In the case of Experimental Example 1, except that the composition of the photocurable resin compound for forming the base material 121 was changed as shown in FIG. Organic EL devices 10A of Experimental Examples 2 and 4 and 5 were manufactured in the same manner as above. The transmission parameters K and Δb ^* calculated in the same manner as in Experimental Example 1 during the manufacturing process were as shown in FIG.

(3) Manufacture of Organic EL Device of Experimental Example 3 As the transparent substrate 11, instead of the glass substrate used in Experimental Example 1, a barrier film obtained by the manufacturing method disclosed in Example 1 of Japanese Patent No. 6691803 ( Water vapor transmission rate measurement result: 1 × 10 ^-6 g / (m ² day)) was cut into a size of 24 mm × 24 mm in the same manner as in Experimental example 1. No. 3 organic EL device 10A was manufactured. The transmission parameters K and Δb ^* calculated in the same manner as in Experimental Example 1 during the manufacturing process were as shown in FIG.

<Evaluation of organic EL device>
(1) Evaluation of organic EL device of Experimental Example 1 (Evaluation of light extraction efficiency)
A reference device having the same configuration as the organic EL device 10A of Experimental Example 1 was manufactured, except that it did not have a light extraction layer.

Using a total luminous flux measurement device, the total luminous flux of the organic EL device 10A was measured under the condition of a current density of 2.5 mA/cm ² , and the external quantum efficiency (EQE) was calculated as the light extraction efficiency. Furthermore, the EQE was similarly calculated for the reference device. After that, the EQE improvement factor was obtained by dividing the EQE of the organic EL device 10A by the EQE of the reference device. The calculation results were as shown in FIG.

(Evaluation of storage life)
Power was applied to the organic EL device 10A to emit light, and after confirming that uniform light emission was obtained, the device was stored under accelerated conditions of 60° C. and 90% RH. The light emitting state was checked every 100 hours, and the area ratio of the non-light emitting portion (dark spot) to the light emitting portion was determined. Evaluation was made based on the following evaluation criteria based on the time for which the area ratio of the non-light-emitting portion was 3% or more. The evaluation results were as shown in FIG.
Evaluation A ⁺ : More than 1000 hours Evaluation A: 200 hours or more and 1000 hours or less Evaluation B: Less than 200 hours

(2) Evaluation of organic EL devices of Experimental Examples 2 to 5 (Evaluation of light extraction efficiency)
A reference device having the same configuration as the organic EL device 10A of each of Experimental Examples 2 to 5 was manufactured, except that it did not have a light extraction layer.

Experimental Examples 2 to 5 were conducted in the same manner as in Experimental Example 1 except that the organic EL devices 10A of Experimental Examples 2 to 5 were used, and the reference devices of Experimental Examples 2 to 5 were used. obtained the EQE enhancement factor at . The calculation results were as shown in FIG.

(Evaluation of storage life)
Using the same method and evaluation criteria as in Experimental Example 1, the storage life of the organic EL device 10A of each of Experimental Examples 2 to 5 was evaluated using the same evaluation criteria as in Example 1. The evaluation results were as shown in FIG.

From the results shown in FIG. 7, in Experimental Examples 1 to 3 and 5 in which the transmission parameter K is 4.0×10 ⁻² cm/h ^0.5 or less, the EQE improvement ratio is greater than 1 and the storage is for 200 hours or more. I was able to secure my life. On the other hand, in Experimental Example 4, in which the transmission parameter K is less than 4.0×10 ⁻² cm/h ^0.5 , even though an EQE improvement ratio greater than 1 could be secured, a storage life of 200 h or more could not be secured. .

That is, it can be understood that a good storage life can be obtained while improving the light extraction efficiency when the transmission parameter K is 4.0×10 ⁻² cm/h ^0.5 or less. With such a good storage life, the organic EL device 10A can be stably driven for a longer period of time.

Comparing Experimental Examples 1 to 3 with Experimental Example 5, the permeation parameter K is 4.0×10 ⁻² cm/h ^0.5 or less and Δb ^* is 5 or less, so that the storage life is ensured. However, it can be understood that the light extraction efficiency can be further improved.

The present invention is not limited to the above embodiments and experimental examples, but includes the scope indicated by the claims, and all changes within the meaning and scope equivalent to the claims intended to be included.

For example, the transparent electrode 13 may be the cathode and the reflective electrode 15 may be the anode.

When the organic EL device includes a sealing member, the sealing member may be bonded to the device substrate so as to cover the end surface (side surface) of the device substrate, for example. The sealing member may be a cap-shaped (or frame-shaped) sealing member with one side open. In this case, the configuration on the light extraction layer can be covered by arranging the sealing member so that the open-side end of the sealing member faces the device substrate side. The cap-side sealing member is attached to the device substrate by fixing the open end of the sealing member to the device substrate using an adhesive.

By raising the refractive index of the light extraction layer to the same or higher than that of the organic EL layer, the light generated in the light emitting layer of the organic EL layer is taken into the light extraction layer with less loss such as total reflection, resulting in light extraction efficiency. is increasing. Therefore, for example, by making the refractive index of the transparent substrate equal to or higher than that of the organic EL layer, the same effect can be exhibited even when the light extraction layer is arranged on the opposite side of the transparent electrode.

The present invention can also be applied to light-emitting devices other than organic EL devices. For example, the light-emitting layer may be made of an inorganic material.

A light-outcoupling film may be attached to the side of the transparent substrate opposite to the side on which the light-outcoupling layer is arranged. Light extraction films include those coated with scattering particles and those that improve the light extraction efficiency by surface shaping such as microlenses, but the light extraction efficiency is maximized in combination with the light extraction layer. An appropriate light extraction film may be selected. The light extraction film can reduce total reflection loss caused by the refractive index difference between the transparent substrate and the air interface.

The above embodiments and various modifications may be combined as appropriate without departing from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10, 10A... Organic EL device (light emitting device), 11... Transparent substrate, 12... Light extraction layer, 12a... Light scattering layer, 12b... Flattening layer, 13... Transparent electrode, 14... Organic EL layer, 14a... Light emitting layer (Organic light-emitting layer) 15 Reflective electrode 16 Barrier layer 40 Laminate 41 First layer 42 Second layer 121 Base material 122 Scattering particles.

Claims (6)

It comprises a transparent substrate, a transparent electrode, a reflective electrode, and a luminescent layer, the transparent electrode being disposed on the transparent substrate, and the luminescent layer being disposed between the transparent electrode and the reflective electrode. a light emitting device comprising:
A light extraction layer disposed on the optical path of the light emitted from the light emitting layer and for extracting the light emitted from the light emitting layer to the outside,
The light extraction layer has a light scattering layer containing a base material and scattering particles having a refractive index different from that of the base material,
The transmission parameter of the resin contained in the light scattering layer is 4.0×10 ⁻⁴ m/h ^0.5 or less.
luminous device. further comprising a barrier layer having a refractive index equal to or higher than the refractive index of the base material between the light extraction layer and the transparent electrode;
the water vapor permeability of the transparent substrate is lower than the water vapor permeability of the barrier layer;
11. The light emitting device of claim 1. the water vapor transmission rate of the transparent substrate is less than 1/10 of the water vapor transmission rate of the barrier layer;
3. A light emitting device according to claim 2. The light extraction layer is arranged between the transparent substrate and the transparent electrode,
The light extraction layer further comprises a planarization layer disposed on the transparent electrode side of the light scattering layer,
The light extraction layer is a layer that satisfies the following condition (A):
A light-emitting device according to any one of claims 1-3.
Condition (A):
A laminate obtained by forming a first layer having the same structure as the light scattering layer on the transparent substrate by a coating method and forming a second layer having the same structure as the flattening layer by a coating method. The first hue of is called b ^* _1, and after degassing the laminate, the laminate was heat-treated for 15 minutes ± 10 seconds so that the temperature of the laminate was 230 ° C ± 5 ° C. The difference Δb ^* between the first hue and the second hue represented by the formula (I) is 5 or less when the second hue of the laminate afterward is referred to as b ^* _2.
Δb ^* =(b ^* _2)-(b ^* _1) (I) wherein the light-emitting layer is an organic light-emitting layer;
A light-emitting device according to any one of claims 1-4. A light scattering layer having a base material and scattering particles having a refractive index different from that of the base material,
The transmission parameter of the resin contained in the light scattering layer is 4.0×10 ⁻⁴ m/h ^0.5 or less.
light extraction layer.

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