JP5973812B2 - Organic electroluminescent device, surface light source, and lighting device - Google Patents

Description

  The present invention relates to an organic electroluminescent element (sometimes referred to as “organic EL element” or “organic electroluminescence element”), a surface light source, and an illumination device.

  An organic electroluminescent element is a self-luminous light emitting device, and is expected to be used for displays and lighting. For example, an organic electroluminescent display has advantages in display performance such as higher visibility than conventional CRTs and LCDs and no viewing angle dependency. In addition, there is an advantage that the display can be made lighter and thinner. On the other hand, in addition to the advantages that organic electroluminescence lighting can be reduced in weight and thickness, it has the potential to realize illumination in a shape that could not be realized by using a flexible substrate. Yes.

The organic electroluminescent element has a pair of electrodes including an anode and a cathode on a substrate, and an organic layer including at least one organic light emitting layer between the pair of electrodes. In order to take out the light generated in the organic light emitting layer, at least one of the anode and the cathode needs to be an electrode having transparency (transparent electrode). As the electrode having transparency, indium tin oxide (ITO ) Is generally used.
In the organic electroluminescent element, light generated in the organic light emitting layer passes through the transparent electrode and the transparent substrate and is extracted to the outside of the organic electroluminescent element. However, the light exceeds the critical angle determined by the output medium, the incident medium, and the refractive index. The emitted light cannot be extracted, is totally reflected at the interface between the two media, is confined inside the organic electroluminescent element, and is lost. In the calculation based on Snell's law of classical refraction, the refractive index n of the organic light emitting layer is 1.8 (according to Non-Patent Document 1, the refractive index n of the organic light emitting layer is 1.7 to 1.85). When the light distribution of light emitted from the organic light emitting layer is Lambertian, the light extraction efficiency up to air is only about 30% due to the difference between the refractive index of the organic light emitting layer and the refractive index of air. The remaining 70% of the light is confined inside the organic electroluminescence device due to the difference in refractive index, and there is a problem that it cannot be emitted to the air.
FIG. 22 shows a light propagation principle diagram of a general organic EL element having a configuration of a transparent substrate, a transparent electrode, an organic light emitting layer, and a reflective electrode. However, the document PONEER R & D Vol. 11 No. 1, pp21-28, the organic light emitting layer has a refractive index n of 1.7 to 1.85, and is a commonly used transparent electrode, tin-doped indium oxide (ITO) (refractive index n = 2.0). ZnO (refractive index n = 1.95), SnO ₂ (refractive index n = 2.0), In ₂ O ₃ (refractive index n = 1.9 to 2.0), TiO ₂ (refractive index n = 1). .90) has a refractive index larger than that of the organic layer including the organic light emitting layer, and does not affect the total reflection between the organic layer and the air. Part ", and the refractive index of the organic light emitting part was represented as 1.8.
In FIG. 22, a light beam a emitted from the organic light emitting unit is a light beam having a radiation angle smaller than the total reflection critical angle due to a difference in refractive index between the organic light emitting unit and air, and can radiate to the air. Since it is larger than the critical angle, it is totally reflected at the interface and cannot be taken out, resulting in loss. The proportion of light a is about 30%.

For this reason, various proposals have been made to improve light extraction efficiency in organic electroluminescent devices.
Patent Document 1 describes an organic electroluminescent element including a transparent substrate, a light diffusion layer, a transparent electrode, an organic light emitting layer, and a reflective electrode in this order. According to this configuration, light emitted from the organic light emitting layer is scattered by the light diffusion layer, and the light traveling angle is converted, so that the light can be emitted to the air.
Patent Document 2 describes a light-emitting device having an organic electroluminescent element, a light-transmitting material having a high refractive index, and a concave reflector. According to this configuration, light emitted from the organic light emitting layer strikes the concave reflector through the high refractive index light-transmitting material, and the organic electroluminescent element is disposed at the focal point of the concave reflector. Can be radiated into the air.
Patent Document 3 describes an organic electroluminescence device including a transparent substrate, a light scattering layer, a transparent electrode, an organic light emitting layer, a transparent electrode, a low refractive index isolation layer, and a reflective layer in this order.
Patent Document 4 includes a reflective electrode, an organic light emitting layer, a transparent electrode, a light guide part, and a reflective part, and the reflective part has a sawtooth cross section in which triangles are continuous in the light emission direction, and There is described an organic LED element composed of concave and convex portions arranged so that one oblique side of a triangle faces an exit surface.

JP 2004-296429 A JP 2004-119147 A Japanese Patent No. 4665340 JP 2003-168553 A

FIG. 23 shows a principle of light propagation of the organic EL element of Patent Document 1. The element of FIG. 23 is obtained by adding a light extraction layer between the transparent substrate and the organic light emitting unit in the element of FIG. By providing the light extraction layer, the light rays b and c in FIG. 22 are guided to the light extraction layer, scattered by the light extraction layer, and emitted to the air by changing the light emission angle.
However, in the element having this structure, light rays d and e that return scattered light to the inside of the element are also generated. In order to extract the light beam d and the light beam e, the metal reflection electrode is used to reflect the light beam d and the light beam e and radiate to the light extraction layer side. More absorption occurs, resulting in loss. Further, every time the light beam reciprocates inside the organic EL element, a loss occurs due to absorption of the organic layer.

FIG. 24 shows a light propagation principle diagram of the organic EL element of Patent Document 2. In FIG. The organic EL element of FIG. 24 has a configuration of reflective electrode / organic layer / transparent electrode, and has a concave reflector facing the transparent electrode with a light transmissive material interposed therebetween. A conical convex portion is provided at the center of the concave reflector. In this configuration, the light emitted from the organic light emitting layer hits the concave reflector through the light-transmitting material having a high refractive index, and the organic EL element is disposed at the focal point of the concave reflector. And then radiates to the air.
However, if the light-transmitting material that guides light from the organic EL element to the concave reflecting surface is a high-refractive index material having a refractive index comparable to that of the organic light emitting layer, the cost is high. On the other hand, when the light-transmitting material is smaller than the refractive index of the organic light emitting layer, total reflection occurs between the light-transmitting material and the transparent electrode of the organic EL element, and light from the total reflection cannot reach the concave reflecting surface. Cannot be improved.
Moreover, since the light reflected by the concave reflecting surface passes through the organic layer again, a part of the light is absorbed by the organic layer, and the light extraction efficiency is lowered.
Furthermore, since the organic EL element must be arranged near the focal point of the concave reflector in order to convert the light emission angle to approximately the front, the concave reflector is sufficiently larger than the organic EL element (the size of the concave body is This is not effective unless it is at least three times that of the organic EL element), and there is also a problem that the organic EL element is enlarged.

FIG. 25 shows a principle of light propagation of the organic EL element disclosed in Patent Document 3. The device of FIG. 25 is obtained by adding a low refractive index layer between the reflective layer and the organic light emitting portion in the device of FIG. As in Patent Document 1, light emitted from the organic EL element is scattered by the light extraction layer to extract a part of the light, and the remaining light beam f and light beam g return to the organic EL element. Here, total reflection due to the difference in refractive index between the organic light emitting portion and the low refractive index layer is provided by providing a low refractive index layer between the organic light emitting portion including the organic light emitting layer and the transparent electrode and the reflective layer. , The high radiation angle light beam f can be reflected and extracted by the light extraction layer of the organic EL element without being absorbed by the metal electrode as in Patent Document 1. The low radiation angle light beam g passes through the low refractive index layer, is reflected by the reflective layer, enters the organic EL element again, and is emitted to the light extraction side (air side).
However, in the element of this configuration, every time the light returned to the organic EL element reciprocates between the light extraction layer and the low refractive index layer, a loss due to light absorption of the organic light emitting portion occurs, and the light extraction efficiency There is a problem that improvement cannot be sufficiently achieved.
Further, in the case where the reflective layer is a metal such as silver (Ag) or aluminum (Al), the reflectivity of light by the metal varies depending on the refractive index of the reflected region, and the greater the refractive index of the reflected region, The reflectance of light in the metal is small and the absorptance is large. In addition, the larger the refractive index of the low refractive index layer, the smaller the difference in refractive index between the low refractive index layer and the organic light emitting layer, so that less light is totally reflected and more incident on the low refractive index layer. More light is absorbed by the metal.
Therefore, in the low refractive index layer composed of a photosensitive polymer or an inorganic layer specifically described in Patent Document 3, the light extraction efficiency is not sufficiently improved.

  An object of the present invention is to solve the above-described problems and to provide an organic electroluminescent device excellent in light extraction efficiency.

The present inventors have intensively studied to solve the above problems, and have a transparent substrate, a light extraction layer, a first transparent electrode, an organic layer including at least one organic light emitting layer, and a second transparent electrode. In the double-sided light emitting organic EL element, an air layer and a reflector are provided in this order on the second transparent electrode side, and one protrusion is formed with the surface of the reflector facing the second transparent electrode side. It has been found that an organic EL light emitting device capable of achieving high light extraction efficiency can be obtained by using a specific shape.
That is, the means for solving the above problems are as follows.

[1]
A laminate having a transparent substrate, a light extraction layer for diffusing light generated in the organic light emitting layer to the transparent substrate side, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order;
A layered body on the side having the second transparent electrode with respect to the transparent substrate, provided with a gap between the layered body and a reflector that reflects light generated in the organic light emitting layer;
The surface on the laminate side of the reflector has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate monotonously increases as the distance from the point or line increases. Has a shape,
The organic electroluminescent element in which the reflector covers the whole organic light emitting layer in planar view in the lamination direction of a laminated body.
[2]
The organic electroluminescent element according to [1], wherein a low refractive index layer having a refractive index lower than that of the organic light emitting layer is present between the laminate and the reflector.
[3]
The organic electroluminescent element according to [2], wherein the low refractive index layer is an air layer.
[4]
The organic electroluminescent element according to any one of [1] to [3], wherein the reflector has a spherical shape, a conical shape, a pyramid shape, or a triangular prism shape.
[5]
The surface of the reflector on the laminate side has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate continuously increases as the distance from the point or line increases. The organic electroluminescent element according to any one of [1] to [4], which has a shape to be formed.
[6]
The area on the reflector side of the organic light emitting layer is S,
When the maximum distance between the surface of the laminate and the reflector is D,
The organic electroluminescent element according to any one of [1] to [5], wherein √S and D satisfy the following formula (1).
0.3 ≦ D / √S Formula (1)
[7]
In a plan view in the stacking direction of the stacked body, the shape of the organic light emitting layer is square, and the side length of the square is W,
When the maximum distance between the surface of the laminate and the reflector is D,
The organic electroluminescent element according to any one of [1] to [6], wherein W and D satisfy the following formula (2).
0.5 ≦ D / W Formula (2)
[8]
The organic electroluminescent element according to any one of [1] to [7], wherein a surface of the reflector is spherical.
[9]
In a plan view in the stacking direction of the stacked body, the shape of the organic light emitting layer is square, and the side length of the square is W,
When the radius of curvature of the reflector surface is R,
The organic electroluminescent element according to [8], wherein W and R satisfy the following formula (3).
0.1 ≦ R / W ≦ 3 Formula (3)
[10]
The organic electroluminescent element according to any one of [1] to [9], wherein the reflector is made of a metal material or a diffuse reflector having a reflectance of 90% or more.
[11]
The light extraction layer is the organic electroluminescence device according to any one of [1] to [10], wherein the light extraction layer is a fine particle diffusion layer containing scattering fine particles.
[12]
The organic electroluminescence device according to any one of [1] to [11], further including a second reflector that further reflects the light reflected by the reflector toward the transparent substrate side.
[13]
The organic electroluminescent element according to [12], wherein the second reflector is provided in contact with the reflector and the transparent substrate.
[14]
The organic electroluminescent element according to [13], wherein the second reflector is provided so as to form an acute angle with the transparent substrate.
[15]
The organic electroluminescent element according to any one of [1] to [14], wherein the reflector is provided in a sealing can that seals the laminate.
[16]
The organic electroluminescent element according to [15], wherein the reflector is provided in the sealing can with a cavity between the reflector and the sealing can and has a desiccant in the cavity.
[17]
The organic electroluminescent element according to any one of [1] to [16], wherein a second light extraction layer is further provided on the reflector side of the second transparent electrode.
[18]
The surface light source containing the organic electroluminescent element of any one of [1]-[17].
[19]
[1] A lighting device including the organic electroluminescent element according to any one of [17].

  ADVANTAGE OF THE INVENTION According to this invention, the organic electroluminescent element excellent in light extraction efficiency can be provided.

It is the schematic which shows the perspective view of an example of the organic electroluminescent element of this invention. It is the schematic which shows sectional drawing of an example of the organic electroluminescent element of this invention. It is the schematic which planarly viewed an example of the organic electroluminescent element of this invention. It is the schematic which shows the perspective view of an example of the organic electroluminescent element of this invention. It is the schematic which shows the perspective view of an example of the organic electroluminescent element of this invention. It is the schematic for demonstrating a curvature radius in case the reflector of the organic electroluminescent element of this invention is a spherical surface. 1 is a schematic view showing an organic electroluminescent element of Example 1. FIG. 3 is a schematic view showing an organic electroluminescent element of Example 2. FIG. 6 is a schematic view showing an organic electroluminescent element of Example 3. FIG. FIG. 6 is a schematic view showing an organic electroluminescent element of Example 4. 6 is a schematic view showing an organic electroluminescent element of Example 5. FIG. 6 is a schematic view showing an organic electroluminescent element of Example 6. FIG. It is the schematic which shows the organic electroluminescent element of the calculation model 1. It is the schematic which shows the organic electroluminescent element of the calculation model 2. FIG. It is the schematic which shows the organic electroluminescent element of the calculation model 3. It is the schematic which shows the organic electroluminescent element of the calculation model 4. In calculation models 1-4, it is the graph which showed the relation between D / W and magnification of light extraction efficiency. In calculation model 3, it is the graph which showed the relationship between R / W and the magnification of light extraction efficiency. It is the schematic which shows the organic electroluminescent element of the calculation model 5. It is the schematic which shows the organic electroluminescent element of the calculation model 6. In calculation models 5-6, it is the graph which showed the relationship between the refractive index of a low refractive index layer, and the magnification of light extraction efficiency. It is the schematic which shows an example of the conventional organic electroluminescent element. It is the schematic which shows an example of the organic electroluminescent element of patent document 1. FIG. It is the schematic which shows an example of the organic electroluminescent element of patent document 2. FIG. It is the schematic which shows an example of the organic electroluminescent element of patent document 3. FIG.

The organic electroluminescent element of the present invention comprises a transparent substrate, a light extraction layer for diffusing light generated in the organic light emitting layer toward the transparent substrate, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order. A laminate having
A reflector that reflects the light generated in the organic light emitting layer provided on the side of the laminate that has the second transparent electrode with respect to the transparent substrate and is spaced from the laminate;
The surface on the laminate side of the reflector has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate becomes monotonous as the distance from the point or line increases. Has an increasing shape,
In the planar view in the stacking direction of the stacked body, the reflector is an organic electroluminescent element covering the entire organic light emitting layer.

FIG. 1 shows a schematic view (perspective view) of an example of the organic electroluminescent element of the present invention.
The organic electroluminescent element 100 described in FIG. 1 includes a laminate 10 having a transparent substrate 1, a light extraction layer 2, a first transparent electrode 3, an organic light emitting layer 4, and a second transparent electrode 5 in this order, On the side of the laminate 10 that has the second transparent electrode 5 with respect to the transparent substrate 1, the laminate 10 is provided with a reflector 6 provided at a distance from the laminate 10. Between the laminated body 10 and the reflector 6, a low refractive index layer (preferably an air layer) having a refractive index lower than that of the organic light emitting layer is provided.
The surface of the reflector 6 on the laminate 10 side has one point where the distance between the reflector 6 and the laminate 10 is the shortest, and the distance between the reflector 6 and the laminate 10 increases as the distance from the point increases. Has a monotonically increasing shape.
FIG. 2 is a schematic cross-sectional view of the organic electroluminescent element of FIG. 1 as viewed from the side.
FIG. 3 shows a schematic diagram when viewed from the stacking direction A of the stacked body 10 in FIG.
As shown in FIG. 3, the reflector 6 covers the entire organic light emitting layer 4 in a plan view in the stacking direction A of the stacked body 10. Point P represents a point where the distance between the reflector 6 and the laminate 10 is the shortest. W represents the side length of one side of the organic light emitting layer 4 when the shape of the organic light emitting layer 4 is a square in plan view in the stacking direction A of the stacked body 10.
In FIG. 3, only the organic light emitting layer 4 of the laminate 10 is illustrated, and the transparent substrate 1, the light extraction layer 2, the first transparent electrode 3, and the second transparent electrode 5 are illustrated. Absent.

  FIG. 2 shows a principle of light propagation of the organic electroluminescence device of the present invention. In the organic electroluminescent device 100 of the present invention shown in FIG. 2, light emitted from the organic light emitting layer 4 is radiated and scattered to the light extraction layer 2, and at a certain rate on the light extraction side (transparent substrate 1 side). Radiates into the front air (light ray a) and other light returns into the organic EL element. Of the light rays f, g, and h returning to the inside of the element, the light beam f is light having an angle larger than the total reflection critical angle due to the difference between the refractive index of the organic light emitting layer and the refractive index of the low refractive index layer. Use it to return to the light extraction layer. On the other hand, light rays g and h of low radiation angle light radiate to the low refractive index layer provided between the organic light emitting layer 4 and the reflector 6 and are reflected by the surface of the reflector 6 to change the radiation direction. Then, avoid the organic EL element and radiate to the front (transparent substrate 1 side). As a result, high-angle light such as the light beam f is prevented from being absorbed by the reflector 6, and low-angle light such as the light beam g and the light beam h is absorbed by the organic layer by returning to the inside of the organic electroluminescent element. Therefore, an organic EL light emitting element with high light extraction efficiency is realized.

The organic electroluminescent element of the present invention has the above-described configuration, but may further include other members as necessary.
Hereinafter, each member of the organic electroluminescent element of the present invention will be described.

[Transparent substrate]
The transparent substrate contained in the organic electroluminescent element of the present invention will be described.
The shape, structure, size, material, etc. of the transparent substrate are not particularly limited and can be appropriately selected according to the purpose. Examples of the shape include a flat plate shape, and the structure is as follows. May have a single-layer structure or a laminated structure, and the size can be appropriately selected.
The material for the transparent substrate is not particularly limited and may be appropriately selected depending on the intended purpose. For example, inorganic materials such as yttria-stabilized zirconia (YSZ) and glass (such as alkali-free glass and soda lime glass), polyethylene Examples thereof include polyester resins such as terephthalate (PET) and polyethylene naphthalate (PEN), polycarbonate, polyimide resin (PI), polyethylene, polyvinyl chloride, polyvinylidene chloride, polystyrene, and styrene-acrylonitrile copolymer. These may be used individually by 1 type and may use 2 or more types together.
The surface of the substrate is preferably subjected to a surface activation treatment in order to improve adhesion with a light extraction layer provided thereon. Examples of the surface activation treatment include glow discharge treatment, corona discharge treatment, and silane coupling treatment of a glass substrate.
The transparent substrate may be appropriately synthesized or a commercially available product may be used.
There is no restriction | limiting in particular as thickness of a transparent substrate, According to the objective, it can select suitably, 10 micrometers or more are preferable and 50 micrometers or more are more preferable.
The transmittance of the transparent substrate in the visible light range (wavelength 400 to 780 nm) is preferably 90% or more.
The refractive index of the transparent substrate is preferably from 1.3 to 1.8, more preferably from 1.4 to 1.7, and still more preferably from 1.4 to 1.6. When the refractive index of the transparent substrate is 1.3 or more, the refractive index difference between the transparent substrate and the light extraction layer does not become too large, and when light from the light extraction layer enters, Fresnel reflection does not become too strong, Light extraction efficiency is easy to improve. When the refractive index of the transparent substrate is 1.8 or less, the difference in refractive index between the transparent substrate and air (light emission side) does not become too large, Fresnel reflection does not become too strong, and light extraction efficiency is easily improved.

[Light extraction layer]
The light extraction layer included in the organic electroluminescent element of the present invention will be described.
The light extraction layer is preferably a fine particle layer.
The fine particle layer contains at least a polymer and fine particles, and further contains other components as necessary.

The refractive index of the polymer in the fine particle layer is preferably different from the refractive index of the fine particles. When a polymer having a refractive index equivalent to the refractive index of the transparent substrate or a refractive index equivalent to that of the organic light emitting layer contains fine particles having a refractive index different from that of the polymer, the organic electroluminescent layer emits the polymer to the polymer. Each time the light hits the fine particle, the light is scattered and the light emission angle is converted due to the difference in refractive index between the polymer and the fine particle, so the light with a high emission angle that is originally totally reflected is converted into a low emission angle. Then, light is emitted from the fine particle layer (or transparent substrate) to the air. In addition, the light having a high radiation angle is scattered in the direction of the reflective electrode, and when reflected by the reflective electrode, it is emitted again to the fine particle layer, and the radiation angle is converted. It is preferable in that it can improve the light extraction efficiency of the organic electroluminescent device.
As described above, the refractive index of the polymer in the fine particle layer is preferably equal to the refractive index of the transparent substrate.

-Fine particles-
The fine particles are not particularly limited as long as the refractive index is different from the refractive index of the polymer of the fine particle layer and can scatter light, and can be appropriately selected according to the purpose. It may be fine particles, and preferably contains two or more fine particles.

Examples of the organic fine particles include polymethyl methacrylate beads, acrylic-styrene copolymer beads, melamine beads, polycarbonate beads, polystyrene beads, cross-linked polystyrene beads, polyvinyl chloride beads, benzoguanamine-melamine formaldehyde beads, and the like.
Examples of the inorganic fine particles include ZrO ₂ , TiO ₂ , Al ₂ O ₃ , In ₂ O ₃ , ZnO, SnO ₂ , Sb ₂ O ₃ , and the like. Among these, TiO ₂ , ZrO ₂ , ZnO, and SnO ₂ are particularly preferable.

The refractive index of the fine particles is not particularly limited as long as it is different from the refractive index of the polymer of the fine particle layer, and can be appropriately selected according to the purpose, but is preferably 1.35 to 2.6, More preferably, it is 1.45 to 2.1.
The refractive index of the fine particles is determined by measuring the refractive index of the refractive liquid using, for example, an automatic refractive index measuring device (KPR-2000, manufactured by Shimadzu Corporation), and then a precision spectrometer (GMR-1DA, manufactured by Shimadzu Corporation). ) And can be measured by the Shribsky method.
The average particle diameter of the fine particles is preferably 0.5 μm to 10 μm, and more preferably 0.5 μm to 6 μm. When the average particle diameter of the fine particles exceeds 10 μm, most of the light is forward scattered, and the ability to convert the angle of light by the scattered fine particles may be reduced. In addition, as described above, light having a high emission angle returns to the organic electroluminescent layer, is reflected by the reflective electrode, and re-radiates again to the fine particle layer. However, the size of the organic electroluminescent device is limited, and the organic electroluminescent layer or reflective layer is reflected. The light extraction efficiency may decrease due to the absorption of the electrode. On the other hand, if the average particle size of the fine particles is less than 0.5 μm, the wavelength becomes smaller than the wavelength of visible light, Mie scattering changes to the Rayleigh scattering region, the wavelength dependency of the scattering efficiency of the fine particles increases, and light emission It is expected that the chromaticity of the element will change greatly and the light extraction efficiency will decrease.
The average particle size of the fine particles can be measured, for example, by an apparatus using a dynamic light scattering method such as Nanotrack UPA-EX150 manufactured by Nikkiso Co., Ltd., or by image processing of an electron micrograph.

The volume filling rate of the fine particles in the fine particle layer is preferably 20% to 70%, and more preferably 30% to 65%. If the volume filling factor is less than 20%, the probability that light incident on the fine particle layer is scattered by the fine particles is small, and the ability to convert the light angle of the fine particle layer is small. If it is not thickened, the light extraction efficiency may decrease. Further, increasing the thickness of the fine particle layer may lead to an increase in cost. Furthermore, light extraction efficiency may be reduced due to increased backscattering. On the other hand, if the volume filling rate exceeds 70%, it may be close to close packing, and the characteristics of the fine particle layer may be difficult to control.
The volume filling rate of the fine particles in the fine particle layer can be measured, for example, by a gravimetric method. First, the specific gravity of particles is measured with a particle specific gravity measuring device (MARK3, manufactured by Union Engineering Co., Ltd.), and the weight of fine particles is measured with an electronic balance (FZ-3000i, manufactured by A & D). Next, a part of the produced fine particle layer is cut off, and the thickness of the fine particle layer is measured with a scanning electron microscope (S-3400N, manufactured by Hitachi High-Tech Co., Ltd.) to obtain the volume filling rate of the fine particles in the fine particle layer. it can.

<< Polymer >>
As described above, the refractive index of the polymer in the fine particle layer is equivalent to the refractive index of the transparent substrate, and is preferably 1.55 to 1.95.
As such a high refractive index polymer, a high refractive index composition in which the polymer is adjusted to a high refractive index with small refractive index fine particles is preferably used.
The high refractive index composition contains the fine particles, small refractive index fine particles, and a matrix, and further contains a dispersant, a solvent, and other components as necessary.

-High refractive index fine particles-
The high refractive index fine particles preferably have a refractive index of 1.80 to 2.8, more preferably 1.9 to 2.8. The average particle size of the primary particles is preferably 3 nm to 100 nm, more preferably 5 nm to 100 nm, and particularly preferably 10 nm to 80 nm.
If the refractive index of the high refractive index fine particles is 1.8 or more, the refractive index of the fine particle layer can be effectively increased, and if the refractive index is 2.8 or less, there is no inconvenience such as coloring of the particles. Therefore, it is preferable. Further, if the average particle diameter of the primary particles of the high refractive index fine particles is 100 nm or less, the haze value of the fine particle layer to be formed is high, and there is no inconvenience such as impairing the transparency of the layer. It is preferable because a high refractive index is maintained.
The particle diameter of the high refractive index fine particles is represented by an average primary particle diameter according to a transmission electron microscope (TEM) photograph. The average primary particle diameter is expressed as an average value of the maximum diameters of the respective fine particles. When the major axis diameter and the minor axis diameter are included, the average value of the major axis diameters of the respective fine particles is defined as the average primary particle diameter.

  As the high refractive index fine particles, for example, oxides such as Ti, Zr, Ta, In, Nd, Sn, Sb, Zn, La, W, Ce, Nb, V, Sm, and Y, composite oxides, and sulfides are mainly used. The particle | grains used as a component are mentioned. Here, the main component means a component having the largest content (mass%) among the components constituting the particles. More preferable high refractive index fine particles in the present invention are particles mainly composed of an oxide or composite oxide containing at least one metal element selected from Ti, Zr, Ta, In, and Sn.

The high refractive index fine particles may contain various elements in the particles (hereinafter, such elements may be referred to as containing elements).
Examples of the contained element include Li, Si, Al, B, Ba, Co, Fe, Hg, Ag, Pt, Au, Cr, Bi, P, and S. In the case of tin oxide and indium oxide, it is preferable to contain an element such as Sb, Nb, P, B, In, V, or halogen in order to increase the conductivity of the particles, and in particular, antimony oxide is contained in an amount of 5% by mass to 20%. Most preferred is a composition containing 1% by mass.

The high refractive index fine particles are inorganic fine particles (hereinafter sometimes referred to as “specific oxides”) mainly composed of titanium dioxide containing at least one element selected from Co, Zr, and Al as contained elements. Can be mentioned. Among these, Co is particularly preferable. The total content of Co, Al, and Zr is preferably 0.05% by mass to 30% by mass with respect to Ti, more preferably 0.1% by mass to 10% by mass, and 0.2% by mass. % To 7% by mass is more preferable, 0.3% to 5% by mass is particularly preferable, and 0.5% to 3% by mass is most preferable.
The contained elements Co, Al, and Zr are present inside or on the surface of the high refractive index fine particles mainly composed of titanium dioxide. It is more preferable that it exists in the high refractive index fine particle mainly composed of titanium dioxide, and it is more preferable that it exists in both the inside and the surface. Among these contained elements, the metal element may exist as an oxide.

As another preferable high refractive index fine particle, composite oxidation of titanium element and at least one metal element (hereinafter also abbreviated as “Met”) selected from metal elements whose oxide has a refractive index of 1.95 or more. In addition, the composite oxide includes inorganic fine particles doped with at least one metal ion selected from Co ions, Zr ions, and Al ions (sometimes referred to as “specific multi-oxide”). Can be mentioned. Here, examples of the metal element whose refractive index of the oxide is 1.95 or more include Ta, Zr, In, Nd, Sb, Sn, Bi, and the like. Among these, Ta, Zr, Sn, and Bi are particularly preferable.
From the standpoint of maintaining the refractive index, the content of the metal ions doped in the specific composite oxide should not exceed 25% by mass with respect to the total amount of metal [Ti + Met] constituting the composite oxide. Preferably, 0.05 mass%-10 mass% are more preferable, 0.1 mass%-5 mass% are still more preferable, 0.3 mass%-3 mass% are especially preferable.

  The doped metal ion may exist as a metal ion or in any form of a metal atom, and may appropriately exist from the surface to the inside of the composite oxide. It is preferable to exist both on the surface and inside of the composite oxide.

  The high refractive index fine particles preferably have a crystal structure. The crystal structure is preferably composed mainly of rutile, a mixed crystal of rutile / anatase, and anatase, particularly preferably a rutile structure. Accordingly, the high refractive index fine particles of the specific oxide or specific double oxide have a refractive index of 1.9 to 2.8, which is preferable. The refractive index is more preferably 2.1 to 2.8, still more preferably 2.2 to 2.8. As a result, the photocatalytic activity of titanium dioxide can be suppressed, and the weather resistance of the fine particle layer itself and the upper / lower layers in contact with the fine particle layer can be remarkably improved.

  A conventionally well-known method can be used for the method of doping the above-mentioned specific metal element or metal ion. For example, methods described in JP-A-5-330825, 11-263620, JP-A-11-512336, European Patent No. 0335773, etc .; ion implantation method [for example, Shunichi Gonda, Jun Ishikawa 3. Eiji Kamijo, “Ion Beam Application Technology” CMC Co., Ltd., published in 1989, Yasushi Aoki, “Surface Science” 18 (5), 262, 1998, Shoichi Anbo, “Surface Science” 20 (2), p. 60, 1999, etc.].

The high refractive index fine particles may be surface-treated. The surface treatment is a modification of the surface of the particles using an inorganic compound and / or an organic compound, whereby the wettability of the surface of the high refractive index fine particles is adjusted, and fine particles in an organic solvent are obtained. Dispersibility and dispersion stability in the refractive index composition are improved. Examples of inorganic compounds adsorbed physicochemically on the particle surface include silicon-containing inorganic compounds (such as SiO ₂ ), aluminum-containing inorganic compounds [Al ₂ O ₃ , Al (OH) _3, etc.], and cobalt. Inorganic compounds containing (CoO ₂ , Co ₂ O ₃ , Co ₃ O ₄ etc.), inorganic compounds containing zirconium [ZrO ₂ , Zr (OH) ₄ etc.], inorganic compounds containing iron (Fe ₂ O ₃ etc.) ), Etc.

  As the organic compound used for the surface treatment, conventionally known surface modifiers of inorganic fillers such as metal oxides and inorganic pigments can be used. For example, it is described in “Pigment Dispersion Stabilization and Surface Treatment Technology / Evaluation”, Chapter 1 (Technical Information Association, published in 2001).

  Specifically, an organic compound having a polar group having an affinity for the surface of the high refractive index fine particles and a coupling compound can be mentioned. Examples of the polar group having an affinity for the surface of the high refractive index fine particles include a carboxy group, a phosphono group, a hydroxy group, a mercapto group, a cyclic acid anhydride group, an amino group, and the like. Compounds containing are preferred. For example, long chain aliphatic carboxylic acids (eg stearic acid, lauric acid, oleic acid, linoleic acid, linolenic acid, etc.), polyol compounds (eg pentaerythritol triacrylate, dipentaerythritol pentaacrylate, ECH (epichlorohydrin) modified glycerol triacrylate Etc.], phosphono group-containing compounds {for example, EO (ethylene oxide) -modified phosphate triacrylate, etc.}, alkanolamines {ethylenediamine EO adducts (5 mol), etc.}.

  As a coupling compound, a conventionally well-known organometallic compound is mentioned, A silane coupling agent, a titanate coupling agent, an aluminate coupling agent, etc. are contained. Silane coupling agents are most preferred. Specific examples include compounds described in paragraph numbers [0011] to [0015] of JP-A Nos. 2002-9908 and 2001-310423. Two or more kinds of compounds used for these surface treatments can be used in combination.

  The high refractive index fine particles are also preferably fine particles having a core / shell structure in which a shell made of another inorganic compound is formed using this as a core. The shell is preferably an oxide composed of at least one element selected from Al, Si, and Zr. Specifically, for example, the contents described in JP-A-2001-166104 can be mentioned.

The shape of the high refractive index fine particles is not particularly limited and may be appropriately selected depending on the purpose. For example, a rice granular shape, a spherical shape, a cubic shape, a spindle shape or an indefinite shape is preferable.
High refractive index fine particles may be used alone or in combination of two or more.
The content of the high refractive index fine particles is not particularly limited and can be appropriately selected according to the purpose, but is preferably in a range where the refractive index of the polymer can be 1.55 to 1.95.

  The matrix is preferably at least one of (A) an organic binder, (B) an organometallic compound containing a hydrolyzable functional group, and a partial condensate of this organometallic compound.

-(A) Organic binder-
As an organic binder of (A),
(1) a conventionally known thermoplastic resin,
(2) A combination of a conventionally known reactive curable resin and a curing agent, or (3) a combination of a binder precursor (such as a curable polyfunctional monomer or polyfunctional oligomer described below) and a polymerization initiator. Binders to be used.

  It is preferable that a high refractive index composition is prepared from a dispersion containing the organic binder (1), (2) or (3), fine particles and a dispersant. This composition is applied onto a support to form a coating film, and then cured by a method according to the component for forming a binder to form a fine particle layer. The curing method is appropriately selected depending on the type of the binder component. For example, a crosslinking reaction or a polymerization reaction of a curable compound (for example, a polyfunctional monomer or a polyfunctional oligomer) is performed by at least one of heating and light irradiation. The method to make it occur is mentioned. Especially, the method of forming the binder which hardened | cured the crosslinking reaction or the polymerization reaction of the curable compound by irradiating light using the combination of said (3) is preferable.

  Furthermore, it is preferable that the dispersing agent contained in the fine particle dispersion is subjected to a crosslinking reaction or a polymerization reaction simultaneously with or after the application of the high refractive index composition.

  The binder in the cured film produced in this way is, for example, a curable polyfunctional monomer or polyfunctional oligomer, which is a precursor of the dispersant, and the precursor of the binder undergoes a crosslinking or polymerization reaction, and the binder has an anion of the dispersant. It becomes a form in which a sex group is incorporated. Furthermore, since the binder in the cured film has a function of maintaining the dispersion state of the high refractive index fine particles, the crosslinked or polymerized structure imparts a film forming ability to the binder and contains the high refractive index fine particles. The physical strength, chemical resistance, and weather resistance in the cured film can be improved.

{Thermoplastic resin (A-1)}
There is no restriction | limiting in particular as a thermoplastic resin of said (1), According to the objective, it can select suitably, For example, a polystyrene resin, a polyester resin, a cellulose resin, a polyether resin, a vinyl chloride resin, a vinyl acetate resin, Examples thereof include a vinyl chloride-vinyl copolymer resin, a polyacrylic resin, a polymethacrylic resin, a polyolefin resin, a urethane resin, a silicone resin, and an imide resin.

{Combination of reactive curable resin and curing agent (A-2)}
As the reactive curable resin (2), it is preferable to use a thermosetting resin and / or an ionizing radiation curable resin.
There is no restriction | limiting in particular as a thermosetting resin, According to the objective, it can select suitably, For example, phenol resin, urea resin, diallyl phthalate resin, melamine resin, guanamine resin, unsaturated polyester resin, polyurethane resin, epoxy resin Aminoalkyd resin, melamine-urea cocondensation resin, silicon resin, polysiloxane resin and the like.
The ionizing radiation curable resin is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a radical polymerizable unsaturated group {(meth) acryloyloxy group, vinyloxy group, styryl group, vinyl group, etc.} And / or a resin having a functional group such as a cationic polymerizable group (epoxy group, thioepoxy group, vinyloxy group, oxetanyl group, etc.), for example, a relatively low molecular weight polyester resin, polyether resin, (meth) acrylic resin, epoxy Examples thereof include resins, urethane resins, alkyd resins, spiroacetal resins, polybutadiene resins, and polythiol polyene resins.

  As necessary for these reactive curable resins, a crosslinking agent (epoxy compound, polyisocyanate compound, polyol compound, polyamine compound, melamine compound, etc.), polymerization initiator (azobis compound, organic peroxide compound, organic halogen compound, Conventionally known compounds such as curing agents such as onium salt compounds and UV photoinitiators such as ketone compounds) and polymerization accelerators (organic metal compounds, acid compounds, basic compounds, etc.) are used. Specific examples include compounds described by Fuzo Yamashita and Tosuke Kaneko “Crosslinking Agent Handbook” (published by Taiseisha, 1981).

{Combination of binder precursor and polymerization initiator (A-3)}
Hereinafter, a method for forming a cured binder by crosslinking or polymerizing a curable compound by light irradiation using the combination of (3), which is a preferable method for forming a cured binder, will be mainly described.

  The functional group of the photocurable polyfunctional monomer or polyfunctional oligomer which is the precursor of the binder may be any of a radical polymerizable functional group and a cationic polymerizable functional group.

  Examples of the radical polymerizable functional group include ethylenically unsaturated groups such as a (meth) acryloyl group, a vinyloxy group, a styryl group, and an allyl group. Among these, a (meth) acryloyl group is preferable, and a polyfunctional monomer containing two or more radical polymerizable groups in the molecule is particularly preferable.

The radical polymerizable polyfunctional monomer is preferably selected from compounds having at least two terminal ethylenically unsaturated bonds. Among these, compounds having 2 to 6 terminal ethylenically unsaturated bonds in the molecule are particularly preferable. Such a compound group is widely known in the polymer material field, and these can be used without any particular limitation.
These can have chemical forms such as monomers, prepolymers (ie, dimers, trimers and oligomers) or mixtures thereof, and copolymers thereof.

  Examples of the radical polymerizable monomer include unsaturated carboxylic acids (for example, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, isocrotonic acid, maleic acid, etc.), esters thereof, amides, and the like. Among these, an ester of an unsaturated carboxylic acid and an aliphatic polyhydric alcohol compound, and an amide of an unsaturated carboxylic acid and an aliphatic polyamine compound are particularly preferable.

  Also, addition reaction products of unsaturated carboxylic acid esters and amides having a nucleophilic substituent such as hydroxyl group, amino group and mercapto group with monofunctional or polyfunctional isocyanates and epoxies, polyfunctional carboxylic acids. A dehydration condensation reaction product with an acid or the like is also preferably used. A reaction product of an unsaturated carboxylic acid ester or amide having an electrophilic substituent such as an isocyanate group or an epoxy group with a monofunctional or polyfunctional alcohol, amine or thiol is also suitable. As yet another example, a compound group in which an unsaturated phosphonic acid, styrene, or the like is substituted for the unsaturated carboxylic acid may be used.

  Examples of the aliphatic polyhydric alcohol compound include alkanediol, alkanetriol, cyclohexanediol, cyclohexanetriol, inositol, cyclohexanedimethanol, pentaerythritol, sorbitol, dipentaerythritol, tripentaerythritol, glycerin, diglycerin and the like. Polymerizable ester compounds (monoesters or polyesters) of these aliphatic polyhydric alcohol compounds and unsaturated carboxylic acids, for example, as described in paragraph numbers [0026] to [0027] of JP-A No. 2001-139663 Compounds.

  Examples of other polymerizable esters include, for example, vinyl alcohol, allyl methacrylate, allyl acrylate, aliphatic alcohols described in JP-B-46-27926, JP-B-51-47334, JP-A-57-196231, and the like. Those having an ester group, those having an aromatic skeleton described in JP-A-2-226149, those having an amino group described in JP-A-1-165613, and the like are also preferably used.

  Specific examples of polymerizable amides formed from aliphatic polyvalent amine compounds and unsaturated carboxylic acids include methylene bis (meth) acrylamide, 1,6-hexamethylene bis (meth) acrylamide, and diethylenetriamine tris (meth) acrylamide. And xylylene bis (meth) acrylamide, and those having a cyclohexylene structure described in JP-B No. 54-21726.

  Furthermore, vinylurethane compounds containing two or more polymerizable vinyl groups in one molecule (Japanese Patent Publication No. 48-41708, etc.), urethane acrylates (Japanese Patent Publication No. 2-16765, etc.), ethylene oxide skeleton Described in JP-B-62-39418, polyester acrylates (JP-B 52-30490, etc.), and further, described in Japan Adhesion Association Vol. 20, No. 7, pages 300-308 (1984). Photocurable monomers and oligomers can also be used. Two or more kinds of these radical polymerizable polyfunctional monomers may be used in combination.

  Next, a cationically polymerizable group-containing compound (hereinafter also referred to as “cationic polymerizable compound” or “cationic polymerizable organic compound”) that can be used for forming the binder of the fine particle layer will be described.

  As the cationic polymerizable compound, any compound that causes a polymerization reaction and / or a crosslinking reaction when irradiated with an active energy ray in the presence of an active energy ray-sensitive cationic polymerization initiator can be used. , Cyclic thioether compounds, cyclic ether compounds, spiro orthoester compounds, vinyl hydrocarbon compounds, vinyl ether compounds, and the like. One or more of the cationically polymerizable organic compounds may be used.

  As the cationically polymerizable group-containing compound, the number of cationically polymerizable groups in one molecule is preferably 2 to 10, and more preferably 2 to 5. The average molecular weight of the compound is preferably 3,000 or less, more preferably 200 to 2,000, and still more preferably 400 to 1,500. If the average molecular weight is not less than the lower limit value, there will be no inconvenience such as volatilization in the film forming process, and if it is not more than the upper limit value, the compatibility with the high refractive index composition is poor. This is preferable because it does not cause problems such as.

  As an epoxy compound, an aliphatic epoxy compound and an aromatic epoxy compound are mentioned, for example.

  Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof, polyglycidyl esters of aliphatic long-chain polybasic acids, homopolymers and copolymers of glycidyl acrylate and glycidyl methacrylate, and the like. Can do. In addition to the above epoxy compounds, for example, monoglycidyl ethers of higher aliphatic alcohols, glycidyl esters of higher fatty acids, epoxidized soybean oil, butyl epoxide stearate, octyl epoxide stearate, epoxidized linseed oil, epoxidized polybutadiene, etc. Can be mentioned. Examples of the alicyclic epoxy compound include polyglycidyl ethers of polyhydric alcohols having at least one alicyclic ring, or unsaturated alicyclic rings (for example, cyclohexene, cyclopentene, dicyclooctene, tricyclodecene, etc. ) Cyclohexene oxide or cyclopentene oxide-containing compound obtained by epoxidizing the containing compound with a suitable oxidizing agent such as hydrogen peroxide or peracid.

  Examples of the aromatic epoxy compound include monovalent or polyvalent phenols having at least one aromatic nucleus, or mono- or polyglycidyl ethers of alkylene oxide adducts thereof. Examples of these epoxy compounds include compounds described in paragraphs [0084] to [0086] in JP-A-11-242101, and paragraphs [0044] to [0046] in JP-A-10-158385. And the compounds described.

  Among these epoxy compounds, aromatic epoxides and alicyclic epoxides are preferable, and alicyclic epoxides are particularly preferable in consideration of fast curability. One of the epoxy compounds may be used alone, or two or more may be used in appropriate combination.

  Examples of the cyclic thioether compound include compounds having a thioepoxy ring instead of the epoxy ring of the epoxy compound.

  Specific examples of the compound containing an oxetanyl group as a cyclic ether include the compounds described in paragraphs [0024] to [0025] in JP-A No. 2000-239309. These compounds are preferably used in combination with an epoxy group-containing compound.

  Examples of the spiro orthoester compound include compounds described in JP 2000-506908 A.

  Examples of vinyl hydrocarbon compounds include styrene compounds, vinyl group-substituted alicyclic hydrocarbon compounds (vinyl cyclohexane, vinyl bicycloheptene, etc.), compounds described in the above radical polymerizable monomers, propenyl compounds {“J. Polymer Science: Part A: Polymer Chemistry ”, vol. 32, page 2895 (1994), etc.}, alkoxy allene compounds {“ J. Polymer Science: Part A: Polymer Chemistry ”, vol. 33, page 2493 (1995), etc.}, vinyl compounds {“ J Polymer Science: Part A: Polymer Chemistry, 34, 1015 (1996), JP-A-2002-29162, etc.}, isopropenyl compound {“J Polymer Science: Part A: Polymer Chemistry ", Vol. 34, p. 2051 (1996), etc.}. You may use these in combination of 2 or more types as appropriate.

  The polyfunctional compound is preferably a compound containing at least one of each selected from the radical polymerizable group and the cationic polymerizable group in the molecule. Examples thereof include compounds described in paragraph numbers [0031] to [0052] in JP-A-8-277320, compounds described in paragraph number [0015] in JP-A 2000-191737, and the like. The compounds used in the present invention are not limited to these.

  The radical polymerizable compound and the cationic polymerizable compound described above are preferably contained in a mass ratio of radical polymerizable compound: cation polymerizable compound in a ratio of 90:10 to 20:80, and 80:20 It is more preferable to contain in the ratio of -30: 70.

  Next, the polymerization initiator used in combination with the binder precursor in the combination (3) will be described in detail.

Examples of the polymerization initiator include a thermal polymerization initiator and a photopolymerization initiator.
The polymerization initiator is preferably a compound that generates radicals or acids upon irradiation with light and / or heat. The photopolymerization initiator preferably has a maximum absorption wavelength of 400 nm or less. Thus, the handling can be performed under a white light by setting the absorption wavelength to the ultraviolet region. A compound having a maximum absorption wavelength in the near infrared region can also be used.

  The compound that generates radicals refers to a compound that generates radicals by irradiation with light and / or heat, and initiates and accelerates polymerization of a compound having a polymerizable unsaturated group. A known polymerization initiator or a compound having a bond with a small bond dissociation energy can be appropriately selected and used. Moreover, the compound which generate | occur | produces a radical can be used individually or in combination of 2 or more types.

  Examples of the compound that generates radicals include conventionally known organic peroxide compounds, thermal radical polymerization initiators such as azo polymerization initiators, organic peroxide compounds (JP 2001-139663 A, etc.), amine compounds (special No. 44-20189), metallocene compounds (JP-A-5-83588, JP-A-1-304453, etc.), hexaarylbiimidazole compounds (US Pat. No. 3,479,185, etc.) ), Disulfone compounds (JP-A-5-239015, JP-A-61-166544, etc.), organic halogenated compounds, carbonyl compounds, organic boric acid compounds, and the like.

  Specific examples of the organic halogenated compound include Wakabayashi et al., “Bull. Chem. Soc Japan”, 42, 2924 (1969), US Pat. No. 3,905,815, and JP-A-5-27830 No., M.C. P. Hutt, “J. Heterocyclic Chemistry”, Vol. 1 (No. 3), (1970) ”and the like, and in particular, an oxazole compound substituted with a trihalomethyl group: an s-triazine compound. More preferable examples include s-triazine derivatives in which at least one mono, di, or trihalogen-substituted methyl group is bonded to the s-triazine ring.

  Examples of the carbonyl compound include, for example, “Latest UV Curing Technology”, pages 60 to 62 [published by Technical Information Association, 1991], paragraph numbers [0015] to [0016] of JP-A-8-134404, And the compounds described in paragraphs [0029] to [0031] of JP-A No. 11-217518, and benzoin compounds such as acetophenone, hydroxyacetophenone, benzophenone, thioxan, benzoin ethyl ether, and benzoin isobutyl ether, p -Benzoic acid ester derivatives such as ethyl dimethylaminobenzoate and ethyl p-diethylaminobenzoate, benzyldimethyl ketal, acylphosphine oxide and the like.

  Examples of the organic borate compound include Japanese Patent Nos. 2764769 and 2002-116539, and Kunz, Martin, “Rad. Tech'98. Proceeding April 19-22, 1998, Chicago”. And the organic borates described in 1. Examples thereof include compounds described in paragraph numbers [0022] to [0027] of JP-A-2002-116539. Examples of other organic boron compounds include JP-A-6-348011, JP-A-7-128785, JP-A-7-140589, JP-A-7-306527, and JP-A-7-292014. Specific examples include organoboron transition metal coordination complexes.

  These radical generating compounds may be added alone or in combination of two or more. As addition amount, it is preferable that it is 0.1 mass%-30 mass% with respect to radical polymerization monomer whole quantity, It is more preferable that it is 0.5 mass%-25 mass%, 1 mass%-20 mass% % Is more preferable. In the range of the addition amount, the high-refractive index composition has high polymerizability without problems with time.

Next, a photoacid generator that can be used as a photopolymerization initiator will be described in detail.
Examples of the photoacid generator include known compounds such as photoinitiators for photocationic polymerization, photodecolorants for dyes, photochromic agents, or known photoacid generators used in microresists, and the like. And the like. Examples of the photoacid generator include organic halogenated compounds, disulfone compounds, onium compounds, and the like. Among these, organic halogenated compounds and disulfone compounds are particularly preferable. Specific examples of the organic halogen compound and the disulfone compound are the same as those described for the compound generating the radical.

  Examples of the onium compound include diazonium salts, ammonium salts, iminium salts, phosphonium salts, iodonium salts, sulfonium salts, arsonium salts, selenonium salts, and the like. For example, paragraph numbers [0058] to [0058] of [JP-A-2002-29162] And the like, and the like.

  As the acid generator, an onium salt is particularly preferably used, and among them, a diazonium salt, an iodonium salt, a sulfonium salt, and an iminium salt are preferable from the viewpoint of photosensitivity at the start of photopolymerization, material stability of the compound, and the like.

  Specific examples of the onium salt include, for example, an amylated sulfonium salt described in paragraph [0035] of JP-A-9-268205 and paragraphs [0010] to [0011] of JP-A-2000-71366. Diaryl iodonium salt or triarylsulfonium salt described in JP-A-2001-288205, sulfonium salt of thiobenzoic acid S-phenyl ester described in JP-A-2001-288205, paragraph number in JP-A-2001-133696 Examples include the onium salts described in [0030] to [0033].

  Other examples of the photoacid generator include photoacid generators having organometallic / organic halides and o-nitrobenzyl type protecting groups described in JP-A-2002-29162, paragraphs [0059] to [0062]. And compounds such as compounds (iminosulfonate, etc.) that generate sulfonic acid upon photolysis.

  These acid generators may be used alone or in combination of two or more. The addition amount of the acid generator is preferably 0.1% by mass to 20% by mass, more preferably 0.5% by mass to 15% by mass, and more preferably 1% by mass to 10% by mass with respect to the total mass of the total cationic polymerizable monomer. % Is more preferable. The addition amount is preferable in the above range from the stability of the high refractive index composition, the polymerization reactivity, and the like.

  The high refractive index composition is 0.5% by mass to 10% by mass of the radical polymerization initiator or 1% by mass to 10% by mass of the cationic polymerization initiator with respect to the total mass of the radical polymerizable compound or the cationic polymerizable compound. The radical polymerization initiator is preferably contained in an amount of 1% by mass to 5% by mass, or the cationic polymerization initiator is preferably contained in an amount of 2% by mass to 6% by mass.

  When the polymerization reaction is carried out by ultraviolet irradiation, a conventionally known ultraviolet spectral sensitizer or chemical sensitizer may be used in combination with the high refractive index composition. Examples of these sensitizers include Michler's ketone, amino acids (such as glycine), and organic amines (such as butylamine and dibutylamine).

  Moreover, when performing a polymerization reaction by near infrared irradiation, it is preferable to use a near infrared spectral sensitizer together. The near-infrared spectral sensitizer used in combination may be a light-absorbing substance having an absorption band in at least a part of the wavelength region of 700 nm or more, and a compound having a molecular extinction coefficient of 10,000 or more is preferable. Furthermore, a value having absorption in the region of 750 nm to 1,400 nm and a molecular extinction coefficient of 20,000 or more is preferable. Moreover, it is more preferable that there is a trough of absorption in the visible light wavelength region of 420 nm to 700 nm, and it is optically transparent.

  As the near-infrared spectral sensitizer, various pigments and dyes known as near-infrared absorbing pigments and near-infrared absorbing dyes can be used. Among these, it is preferable to use a conventionally known near-infrared absorber. Commercially available dyes and literature {for example, “Chemical Industry”, May 1986, pages 45-51, “Near-Infrared Absorbing Dye”, “Development and Market Trends of Functional Dyes in the 1990s”, Chapter 2.3. (1990) CMC, “Special Function Dye” [edited by Ikemori and Pilatani, 1986, issued by CMC Co., Ltd.], J. Am. FABIAN, “Chem. Rev.”, Vol. 92, pp. 1197-1226 (1992)}, a catalog published in 1995 by Nippon Sensitive Dye Research Institute, and Exciton Inc. Can be used as well as known dyes described in laser dye catalogs and patents issued in 1989.

  (B) Organometallic compound containing hydrolyzable functional group and partial condensate of this organometallic compound As the matrix, an organometallic compound containing a hydrolyzable functional group is used to form a coating film by a sol / gel reaction. It is also preferable to form a cured film after formation.

Examples of the organometallic compound include compounds composed of Si, Ti, Zr, Al, and the like.
Examples of the hydrolyzable functional group include an alkoxy group, an alkoxycarbonyl group, a halogen atom, and a hydroxyl group. Among these, alkoxy groups such as a methoxy group, an ethoxy group, a propoxy group, and a butoxy group are particularly preferable. A preferred organometallic compound is an organosilicon compound represented by the following general formula (2) and a partial hydrolyzate (partial condensate) thereof. In addition, it is a well-known fact that the organosilicon compound represented by the general formula (2) is easily hydrolyzed and subsequently undergoes a dehydration condensation reaction.

Formula (2): (R ²¹ ) _β- Si (Y ²¹ ) _4-β
However, In the general formula ^{(2), R 21} represents a substituted or unsubstituted C 1-30 aliphatic group or an aryl group having 6 to 14 carbon atoms. Y ²¹ represents a halogen atom (a chlorine atom, a bromine atom, etc.), an OH group, an OR ²² group, or an OCOR ²² group. Here, R ²² represents a substituted or unsubstituted alkyl group. β represents an integer of 0 to 3, preferably 0, 1 or 2, particularly preferably 1. However, when β is 0, Y ²¹ represents an OR ²² group or an OCOR ²² group.

In the general formula (2), the aliphatic group represented by R ²¹ preferably has 1 to 18 carbon atoms (for example, methyl group, ethyl group, propyl group, butyl group, pentyl group, hexyl group, octyl group, decyl group). , Dodecyl group, hexadecyl group, octadecyl group, benzyl group, phenethyl group, cyclohexyl group, cyclohexylmethyl group, hexenyl group, decenyl group, dodecenyl group, etc.). More preferably, it has 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms. Examples of the aryl group for R ²¹ include a phenyl group, a naphthyl group, and an anthranyl group, and a phenyl group is preferable.

  The substituent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, halogen (fluorine, chlorine, bromine, etc.), hydroxyl group, mercapto group, carboxyl group, epoxy group, alkyl group (methyl group) , Ethyl group, i-propyl group, propyl group, t-butyl etc.), aryl group (phenyl group, naphthyl group etc.), aromatic heterocyclic group (furyl group, pyrazolyl group, pyridyl group etc.), alkoxy group (methoxy) Group, ethoxy group, i-propoxy group, hexyloxy group, etc.), aryloxy group (phenoxy group, etc.), alkylthio group (methylthio group, ethylthio group, etc.), arylthio group (phenylthio group, etc.), alkenyl group (vinyl group, 1-propenyl group etc.), alkoxysilyl group (trimethoxysilyl group, triethoxysilyl group etc.), acyloxy group { Cetoxy group, (meth) acryloyl group etc.}, alkoxycarbonyl group (methoxycarbonyl group, ethoxycarbonyl group etc.), aryloxycarbonyl group (phenoxycarbonyl group etc.), carbamoyl group (carbamoyl group, N-methylcarbamoyl group, N, N-dimethylcarbamoyl group, N-methyl-N-octylcarbamoyl group, etc.), acylamino group (acetylamino group, benzoylamino group, acrylamino group, methacrylamino group, etc.) are preferred.

  Of these substituents, more preferred are a hydroxyl group, a mercapto group, a carboxyl group, an epoxy group, an alkyl group, an alkoxysilyl group, an acyloxy group, and an acylamino group, and particularly preferred are an epoxy group and a polymerizable acyloxy group {( (Meth) acryloyl group} and a polymerizable acylamino group (acrylamino group, methacrylamino group). These substituents may be further substituted.

As described above, R ²² represents a substituted or unsubstituted alkyl group, and the alkyl group is not particularly limited, and examples thereof include the same as the aliphatic group of R ²¹ , and the explanation of the substituent in the alkyl group is R ²¹ .

  The content of the compound of the general formula (2) is preferably 10% by mass to 80% by mass, more preferably 20% by mass to 70% by mass, and more preferably 30% by mass based on the total solid content of the high refractive index composition. It is still more preferable that it is% -50 mass%.

  Examples of the compound of the general formula (2) include compounds described in paragraph numbers [0054] to [0056] of JP-A No. 2001-166104.

  In the high refractive index composition, the organic binder preferably has a silanol group. It is preferable that the binder has a silanol group because the physical strength, chemical resistance, and weather resistance of the fine particle layer are further improved. The silanol group is contained, for example, as a binder forming component constituting a high refractive index composition in a binder precursor (such as a curable polyfunctional monomer or polyfunctional oligomer), a polymerization initiator, or a dispersion of high refractive index fine particles. The organosilicon compound represented by the general formula (2) having a crosslinkable or polymerizable functional group is blended in the high refractive index composition together with the dispersing agent, and the high refractive index composition is coated on the transparent support. Then, the dispersant, the polyfunctional monomer, the polyfunctional oligomer, and the organosilicon compound represented by the general formula (2) can be introduced into the binder by a crosslinking reaction or a polymerization reaction.

  The hydrolysis / condensation reaction for curing the organometallic compound is preferably performed in the presence of a catalyst. Examples of the catalyst include inorganic acids such as hydrochloric acid, sulfuric acid, and nitric acid; organic acids such as oxalic acid, acetic acid, formic acid, trifluoroacetic acid, methanesulfonic acid, and toluenesulfonic acid; sodium hydroxide, potassium hydroxide, ammonia, and the like. Inorganic bases; organic bases such as triethylamine and pyridine; metal alkoxides such as triisopropoxyaluminum, tetrabutoxyzirconium and tetrabutoxytitanate; metal chelate compounds of β-diketones and β-ketoesters. Specific examples include the compounds described in paragraph numbers [0071] to [0083] in JP-A No. 2000-275403.

  The proportion of these catalyst compounds in the composition is preferably 0.01% by mass to 50% by mass, more preferably 0.1% by mass to 50% by mass, and 0.5% by mass to the organometallic compound. 10 mass% is still more preferable. In addition, it is preferable that reaction conditions are suitably adjusted with the reactivity of an organometallic compound.

In the high refractive index composition, the matrix preferably has a specific polar group.
Examples of the specific polar group include an anionic group, an amino group, and a quaternary ammonium group. Specific examples of the anionic group, amino group, and quaternary ammonium group include the same as those described for the dispersant.

-Solvent-
The solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include alcohols, ketones, esters, amides, ethers, ether esters, hydrocarbons, and halogenated hydrocarbons. Is mentioned. Specifically, alcohol (for example, methanol, ethanol, propanol, butanol, benzyl alcohol, ethylene glycol, propylene glycol, ethylene glycol monoacetate, etc.), ketone (for example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, methylcyclohexanone, etc.), ester ( For example, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, ethyl formate, propyl formate, butyl formate, ethyl lactate, etc.), aliphatic hydrocarbons (eg, hexane, cyclohexane), halogenated hydrocarbons (eg, methyl chloroform), aromatic Group hydrocarbons (eg, benzene, toluene, xylene, etc.), amides (eg, dimethylformamide, dimethylacetamide, n-methylpyrrolidone, etc.), ethers (eg, dioxane) Emissions, tetrahydrofuran, ethylene glycol dimethyl ether, propylene glycol dimethyl ether, etc.), ether alcohols (such as 1-methoxy-2-propanol, ethyl cellosolve, methyl carbinol and the like). These may be used individually by 1 type and may use 2 or more types together. Among these, toluene, xylene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and butanol are particularly preferable.
A coating solvent system mainly comprising a ketone solvent (for example, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, etc.) is also preferably used.
The content of the ketone solvent is preferably 10% by mass or more, more preferably 30% by mass or more, and still more preferably 60% by mass or more of the total solvent contained in the high refractive index composition.

  A matrix having a specific polar group is prepared by, for example, blending a dispersion containing high refractive index fine particles and a dispersant with a high refractive index composition, and a binder precursor having a specific polar group as a cured film forming component (specific A curable polyfunctional monomer or polyfunctional oligomer having a polar group) and a polymerization initiator, and a general polar formula having a specific polar group and a crosslinked or polymerizable functional group (2). At least one of the organic silicon compounds, a monopolar monomer having a specific polar group and a crosslinkable or polymerizable functional group, if desired, and coating the coating composition on the transparent support. Then, the above-mentioned dispersant, monofunctional monomer, polyfunctional monomer, polyfunctional oligomer and / or the organosilicon compound represented by the general formula (2) are obtained by crosslinking or polymerization reaction.

  The monofunctional monomer having the specific polar group is preferable because it can function as a dispersion aid for the high refractive index fine particles in the high refractive index composition. Furthermore, after coating, a uniform dispersion of high refractive index fine particles in the fine particle layer is maintained by crosslinking reaction or polymerization reaction with a dispersant, a polyfunctional monomer or polyfunctional oligomer, or a polymerization reaction to maintain a good physical dispersibility. A fine particle layer having excellent strength, chemical resistance and weather resistance can be produced.

  The coating liquid in which the fine particles are added to the high refractive index composition, on the transparent substrate, for example, dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method, It can be prepared by applying by a known thin film forming method such as a micro gravure coating method or an extrusion coating method, followed by drying, light and / or heat irradiation. Preferably, curing by light irradiation is advantageous from rapid curing. Furthermore, it is also preferable to heat-process in the second half of photocuring process.

  The light source for light irradiation may be any one in the ultraviolet light region or near infrared light. Ultraviolet, high pressure, medium pressure, and low pressure mercury lamps, chemical lamps, carbon arc lamps, metal halide lamps may be used as ultraviolet light sources. Xenon lamps, sunlight, etc. Various available laser light sources having a wavelength of 350 nm to 420 nm may be irradiated as a multi-beam. Further, examples of the near-infrared light source include a halogen lamp, a xenon lamp, and a high-pressure sodium lamp. Various available laser light sources having a wavelength of 750 nm to 1,400 nm may be irradiated in a multi-beam form.

In the case of radical photopolymerization by light irradiation, it can be carried out in air or in an inert gas, but in order to shorten the polymerization induction period of the radically polymerizable monomer or sufficiently increase the polymerization rate, etc. It is preferable that the atmosphere has a reduced oxygen concentration. Irradiation intensity of ultraviolet irradiation is ^preferably from 0.1mW / cm ² ~100mW / cm 2 or so, an amount of light irradiation on the coating film surface is 100mJ ^/ cm ² ~1,000mJ ^/ cm 2 is preferred. Further, the temperature distribution of the coating film in the light irradiation step is preferably as uniform as possible, preferably within ± 3 ° C., and more preferably controlled within ± 1.5 ° C. In this range, the polymerization reaction in the in-plane and in-layer depth directions of the coating film proceeds uniformly, which is preferable.

The average thickness of the fine particle layer is preferably 5 μm to 200 μm, and more preferably 5 μm to 50 μm. If the average thickness is less than 5 μm, there is no sufficient light angle conversion by the fine particle layer, and the maximum light extraction efficiency may not be obtained. Increasing the amount of light and returning more light to the inside of the organic electroluminescent element, reducing the light extraction efficiency, and the thick fine particle layer may lead to high costs.
The average thickness can be determined, for example, by cutting a part of the fine particle layer and measuring with a scanning electron microscope (S-3400N, manufactured by Hitachi High-Tech Co., Ltd.).

[First transparent electrode]
The 1st transparent electrode contained in the organic electroluminescent element of this invention is demonstrated.
There is no restriction | limiting in particular as a material of a 1st transparent electrode, According to the objective, it can select suitably, For example, a tin dope indium oxide (ITO) (refractive index = 2.0), zinc dope indium oxide (IZO) ZnO (refractive index = 1.95), SnO ₂ (refractive index = 2.0), In ₂ O ₃ (refractive index = 1.9 to 2.0), TiO ₂ (refractive index = 1.90), etc. Is mentioned. Among these, ITO and IZO are particularly preferable.
The refractive index of the first transparent electrode is preferably 1.65 to 2.2.
The average thickness of the first transparent electrode is preferably 20 nm to 200 nm, and more preferably 40 nm to 100 nm.
The transmittance of the first transparent electrode in the visible light range (wavelength 400 to 780 nm) is preferably 90% or more.

[Organic layer]
The organic electroluminescent element of the present invention has an organic layer including at least one organic light emitting layer.
The organic layer has at least one organic light emitting layer, and may have a hole injection layer, a hole transport layer, an electron injection layer, an electron transport layer, and the like, if necessary. It may be provided with other functions. Various materials can be used for forming each layer.

--Luminescent material--
As the light emitting material, any of a phosphorescent light emitting material, a fluorescent light emitting material and the like can be suitably used.
The light emitting material 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>ΔEa> with the host compound. A dopant satisfying the relationship of 0.2 eV is preferable from the viewpoint of driving durability.
The light emitting material 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. From the viewpoint, the content is preferably 1% by mass to 50% by mass, and more preferably 2% by mass to 50% by mass.

--- Phosphorescent material ---
In general, examples of the phosphorescent material include complexes containing a transition metal atom or a lanthanoid atom.
The transition metal atom is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include ruthenium, rhodium, palladium, tungsten, rhenium, osmium, iridium, gold, silver, copper, and platinum. Rhenium, iridium, and platinum are more preferable, and iridium and platinum are more preferable.

  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 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, JP2002-1235076, JP2003-123982, JP2002-170684, EP121257, JP2002-226495, JP2002-2002 34894, JP 2001-247659, JP 2001-298470, JP 2002-173675, JP 2002-203678, JP 2002-203679, JP 2004-357791, JP 2006-93542, JP 2006-261623, Examples thereof include phosphorescent compounds described in JP-A-2006-256999, JP-A-2007-19462, JP-A-2007-84635, JP-A-2007-96259, and the like. Among these, Ir complex, Pt complex, Cu complex, Re complex, W complex, Rh complex, Ru complex, Pd complex, Os complex, Eu complex, Tb complex, Gd complex, Dy complex, and Ce complex are preferable, and Ir complex , A Pt complex, or a Re complex is more preferable, and an Ir complex, a Pt complex, or a Re complex including at least one coordination mode of a metal-carbon bond, a metal-nitrogen bond, a metal-oxygen bond, and a metal-sulfur bond is further included. In view of luminous efficiency, driving durability, chromaticity, etc., an Ir complex, a Pt complex, or a Re complex containing a tridentate or higher polydentate ligand is particularly preferable.

  Specific examples of the phosphorescent material include the following compounds, but are not limited thereto.

--- Fluorescent material ---
The fluorescent light emitting material is not particularly limited and may be appropriately selected depending on the intended purpose. For example, benzoxazole, benzimidazole, benzothiazole, styrylbenzene, polyphenyl, diphenylbutadiene, tetraphenylbutadiene, naphthalimide, coumarin , Pyran, perinone, oxadiazole, aldazine, pyridine, cyclopentadiene, bisstyrylanthracene, quinacridone, pyrrolopyridine, thiadiazolopyridine, cyclopentadiene, styrylamine, aromatic dimethylidin compound, condensed polycyclic aromatic compound (anthracene, Phenanthroline, pyrene, perylene, rubrene, or pentacene), metal complexes of 8-quinolinol, various metal complexes represented by pyromethene complexes and rare earth complexes, polythiophene Polyphenylene polymer compounds such as polyphenylene vinylene, organic silane, or their derivatives can be mentioned.

-Host material-
As the host material, a hole-transporting host material having excellent hole-transporting property (may be described as a hole-transporting host) and an electron-transporting host compound having excellent electron-transporting property (described as an electron-transporting host) May be used).

--- Hole-transporting host material ---
Examples of the hole transporting host material 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, or derivatives thereof.
Among these, indole derivatives, carbazole derivatives, aromatic tertiary amine compounds, thiophene derivatives, and those having a carbazole group in the molecule are preferred, and compounds having a t-butyl substituted carbazole group are more preferred.

---- Electron-transporting host material ---
Examples of the electron transporting host material include pyridine, pyrimidine, triazine, imidazole, pyrazole, triazole, oxazole, oxadiazole, fluorenone, anthraquinodimethane, anthrone, diphenylquinone, thiopyran dioxide, carbodiimide, fluoreni Heterocyclic tetracarboxylic anhydrides such as redenemethane, distyrylpyrazine, fluorine-substituted aromatic compounds, naphthaleneperylene, phthalocyanines, or derivatives thereof (may form condensed rings with other rings), 8-quinolinol derivatives And various metal complexes represented by metal complexes having metal phthalocyanine, benzoxazole or benzothiazole as a ligand. Among these, 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 include Japanese Patent Application Laid-Open No. 2002-235076, Japanese Patent Application Laid-Open No. 2004-214179, Japanese Patent Application Laid-Open No. 2004-221106, Japanese Patent Application Laid-Open No. 2004-221665, and Japanese Patent Application Laid-Open No. 2004-221068. And compounds described in JP-A No. 2004-327313.

  Specific examples of the hole transporting host material and the electron transporting host material include the following compounds, but are not limited thereto.

-Hole injection layer, hole transport layer-
The hole injection layer or the hole transport layer is a layer having a function of receiving holes from the anode or the layer on 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, Etc. are preferred.

The hole injection layer or the hole transport layer may contain an electron accepting dopant. As the electron-accepting dopant introduced into the hole injection layer or the hole transport 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, and 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. The amount of the electron-accepting dopant varies depending on the type of the material, but is preferably 0.01% by mass to 50% by mass, more preferably 0.05% by mass to 40% by mass with respect to the hole transport layer material. 1 mass% to 30 mass% is particularly preferable.

  The hole injection layer or 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. Also good.

There is no restriction | limiting in particular in the thickness of the said light emitting layer, According to the objective, it can select suitably, 1 nm-5 micrometers are preferable, 5 nm-1 micrometer are more preferable, 10 nm-500 nm are still more preferable.
The method for forming the light emitting layer is not particularly limited and may be appropriately selected depending on the purpose. For example, resistance heating vapor deposition, electron beam, sputtering, molecular lamination method, coating method (spin coating method, casting method, dip coating) Method) and LB method. Among these, resistance heating vapor deposition and a coating method are particularly preferable.

-Electron injection layer, electron transport layer-
The electron injection layer or the electron transport layer is a layer having a function of receiving electrons from the cathode or a layer on 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, the layer containing the like are preferable.

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. Alkali metals such as Li and alkaline earths such as Mg Metals, transition metals including rare earth metals, reducing organic compounds, and the like 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, 0.1 mass%-99 mass% are preferable with respect to electron carrying layer material, 1.0 mass%-80 mass% are still more preferable. 0 mass%-70 mass% is especially preferable.

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

-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 organic light emitting layer from passing to the cathode side, and is usually provided as an organic compound layer adjacent to the light emitting layer on the cathode side. It is done.
On the other hand, the electron blocking layer is a layer having a function of preventing electrons transported from the cathode side to the organic light emitting layer from passing to the anode side, and is usually an organic compound layer adjacent to the organic light emitting layer on the anode side. Provided.
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 still more preferably 10 nm to 100 nm. The hole blocking layer and the electron blocking layer may have a single-layer structure made of one or more of the materials described above, or a multilayer structure made up of a plurality of layers having the same composition or different compositions. Also good.

[Second transparent electrode]
The 2nd transparent electrode contained in the organic electroluminescent element of this invention is demonstrated.
The second transparent electrode preferably functions as a cathode, and generally has only to have a function as an electrode for injecting electrons into the organic compound layer constituting the above-described light emitting layer. There is no restriction | limiting in particular about this etc., According to the use and objective of an organic EL apparatus, it can select suitably from well-known electrode materials.

  Examples of the material constituting the cathode include metals, alloys, metal oxides, electrically conductive compounds, and mixtures thereof. Specific examples include alkali metals (eg, Li, Na, K, Cs, etc.), alkaline earth metals (eg, Mg, Ca, etc.), gold, silver, lead, aluminum, sodium-potassium alloys, lithium-aluminum alloys, magnesium. -Rare earth metals such as silver alloys, indium and 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, the material constituting the cathode is preferably an alkali metal or an alkaline earth metal from the viewpoint of electron injection, and a material mainly composed of aluminum is preferable from the viewpoint of excellent storage stability. The material mainly composed of aluminum is aluminum alone, an alloy of aluminum and 0.01% by mass to 10% by mass of alkali metal or alkaline earth metal, or a mixture thereof (for example, lithium-aluminum alloy, magnesium-aluminum alloy). Etc.).

  The materials for the cathode are described in detail in JP-A-2-15595 and JP-A-5-121172, and the materials described in these public relations can also be applied in the present invention.

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

  Patterning when forming the cathode may be performed by chemical etching such as photolithography, physical etching by laser, or the like, or by vacuum deposition or sputtering with the mask overlaid. It may be performed by a lift-off method or a printing method.

  In the present invention, the arrangement position of the cathode is not particularly limited as long as it is provided so that an electric field can be applied to the light emitting layer, and may be formed on the entire light emitting layer or a part thereof. Also good.

  Further, a dielectric layer made of an alkali metal or alkaline earth metal fluoride or oxide may be inserted between the cathode and the organic compound layer with a thickness of 0.1 nm to 5 nm. This dielectric layer can also be regarded as a kind of electron injection layer. The dielectric layer can be formed by, for example, a vacuum deposition method, a sputtering method, an ion plating method, or the like.

The refractive index of the second transparent electrode is preferably 1.65 to 2.2.
The average thickness of the second transparent electrode is preferably 20 nm to 200 nm, and more preferably 40 nm to 100 nm.
The transmittance of the second transparent electrode in the visible light range (wavelength 400 to 780 nm) is preferably 90% or more.
When the second transparent electrode is a cathode, it can be formed by depositing a thin cathode material to a thickness of 1 nm to 10 nm and further laminating a transparent conductive material such as ITO or IZO.

[Reflector]
The organic electroluminescent device of the present invention includes at least a laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode, and a transparent substrate of the laminate. On the side having the two transparent electrodes, the laminate and a reflector provided with a gap are provided.
The surface on the laminate side of the reflector has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate becomes monotonous as the distance from the point or line increases. Has an increasing shape.
Here, the distance represents the “shortest distance”.
“The distance increases monotonously” includes not only the case where the distance increases continuously but also the case where the distance does not change.

  In order to prevent the reflector from being absorbed in the organic light emitting layer or the like, it is generated in the organic light emitting layer and reflects more light that has traveled to the reflector side so as to travel in the direction of the transparent substrate avoiding the laminate. This makes it possible to efficiently extract light from the light extraction surface.

The light reflectance of the reflector is preferably 50% or more, more preferably 70% or more, and still more preferably 90% or more. Here, the reflectance is a value with respect to the visible light range (wavelength 400 to 780 nm, typically represented by d-line: wavelength 587 nm).
The material which comprises a reflector is not specifically limited. Examples of the material include metals and metal oxides, and metals such as aluminum, silver, gold, and chromium are preferable.
The method for forming the reflector is not particularly limited. For example, vapor deposition, Metal Injection Molding (MIM) method (metal powder injection molding method), plating, cutting molding, vapor deposition method and the like can be mentioned, and MIM method is preferable from the viewpoint of component manufacturing efficiency and precision of shape formation. .
The MIM method is not particularly limited and can be performed with reference to a conventionally known method. An example of the MIM method is described in JP-A-6-2004.
When producing a reflector by the vapor deposition method, a reflective layer material such as Ag is vapor-deposited on a sealing can to produce a flat reflector, and a reflective layer material such as Ag is vapor-deposited on a mold having a curved surface such as a glass lens to reflect the curved surface. A body may be created and combined with an adhesive.

  In addition to the above metal, the reflector is preferably composed of a diffuse reflector having a reflectance of 90% or more. Examples of the diffuse reflection plate having a reflectance of 90% or more include an easily molded light reflection plate MCPOLYCA manufactured by Furukawa Electric. Here, the reflectance is a value with respect to the visible light range (wavelength 400 to 780 nm, typically represented by d-line: wavelength 587 nm).

In order to change the angle of light so that the light incident on the low refractive index layer does not return to the organic layer, the surface of the reflector on the side of the laminate is the point or line with the shortest distance between the reflector and the laminate. It is preferable to have a shape in which the distance between the reflector and the laminate continuously increases as the distance from the point or line increases.
For example, in the organic electroluminescent element of the present invention, the transparent substrate is a flat plate, and the light extraction layer, the first transparent electrode, the organic light emitting layer, and the second transparent electrode are also parallel to the surface on the reflector side of the transparent substrate. When laminated so as to have a surface, the shape of the reflector is preferably a shape having one protrusion toward the organic light emitting layer. As such a shape, a shape having a curved surface (preferably spherical shape), a conical shape, a pyramid shape, or a triangular prism shape is preferable, and a shape having a curved surface (preferably spherical shape) is more preferable. For convex reflectors of the same height, the spherical shape is preferable because the spherical curvature is the largest and the angle conversion capability of light is great. A specific example of the spherical reflector is a convex mirror. It should be noted that the spherical surface is not a complete spherical surface but includes a substantially spherical surface.
FIG. 4 shows a schematic view (perspective view) of an example of the organic electroluminescent element of the present invention. 4 differs from FIG. 1 only in that the surface of the reflector 6 is a quadrangular pyramid.
FIG. 5 shows a schematic view (perspective view) of an example of the organic electroluminescent element of the present invention. The organic electroluminescent element 100 shown in FIG. 5 differs from FIG. 1 only in that the surface of the reflector 6 has a triangular prism shape.

  In the organic electroluminescent element of the present invention, the reflector covers the entire organic light emitting layer in a plan view in the stacking direction of the stacked body. In other words, a projection plane obtained by projecting the organic light emitting layer in a direction perpendicular to the surface of the organic light emitting layer on the reflector side projects the reflector in a direction perpendicular to the surface of the organic light emitting layer. It is preferable that all are included in the projected plane. That is, the reflector is preferably provided so as to face the entire surface of the organic light emitting layer. By doing in this way, the light emitted from the organic light emitting layer and reflected by the reflector proceeds in the direction of the transparent substrate avoiding the laminate, so that it is prevented from being absorbed by the organic light emitting layer and the like. The extraction efficiency can be improved.

Let S be the area of the surface of the organic light emitting layer on the reflector side.
When the maximum value of the distance between the surface of the laminate and the reflector is D (see FIG. 2),
It is preferable from the viewpoint of light extraction efficiency that √S and D satisfy the following formula (1). However, the unit of D and √S is the same (for example, the unit of D and the unit of √S are both “mm”).
0.3 ≦ D / √S Formula (1)
D / √S is more preferably 0.5 or more, and further preferably 0.8 or more.
Further, from the viewpoint that the thickness of the organic electroluminescent element can be made thinner, D / √S is preferably 1.5 or less.

  When the organic light emitting layer has a square shape in plan view in the stacking direction of the stack, and the side length of the square is W (see FIGS. 2 and 3), the relationship between W and S is W = √ S.

When the maximum value of the distance between the surface of the laminate and the reflector is D (see FIG. 2),
It is preferable from the viewpoint of light extraction efficiency that W and D satisfy the following formula (2). However, the unit of D and W is the same (for example, the unit of D and the unit of W are both “mm”).
0.5 ≦ D / W Formula (2)
D / W is more preferably 0.8 or more, and even more preferably 1.0 or more.
Moreover, it is preferable that D / W is 2.0 or less from a viewpoint that the volume of an organic light emitting element can be made smaller.

  Although each value of D and W is not specifically limited, For example, D is about 10 mm-300 mm, and 20 mm-200 mm are preferable. W is preferably 30 mm to 500 mm.

When the reflector has a curved surface (preferably a spherical shape), the organic light emitting layer has a square shape in plan view in the stacking direction of the stack, and the side length of the square is W.
When the radius of curvature of the curved surface of the reflector is R,
It is preferable from the viewpoint of light extraction efficiency that W and R satisfy the following formula (3). However, the units of R and W are the same (for example, the unit of R and the unit of W are both “mm”).
0.1 ≦ R / W ≦ 3 Formula (3)
R / W is more preferably 0.2 or more and 1.5 or less, and further preferably 0.3 or more and 1.3 or less.

Although the value of R is not specifically limited, For example, R is about 5 mm-1000 mm, and 10 mm-800 mm are preferable.
FIG. 6 is a schematic diagram for explaining the radius of curvature R when the surface of the reflector is spherical. As an example, a reflector having a spherical surface has a shape obtained by cutting a sphere having a radius R along a straight line B as shown in FIG.

The surface on the laminate side of the reflector has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate monotonously increases as the distance from the point or line increases. Have a shape to The position of the point or line is not particularly limited, but it is preferable that the point or line is at the center of the reflector from the viewpoint of easily preventing light from returning to the organic layer.
Moreover, it is preferable that the center of the reflector overlaps the center of the organic light emitting layer in a plan view in the stacking direction of the stacked body.
When the center of the organic light emitting layer and the reflector are overlapped, the reflected light is radiated to the transparent substrate side with good symmetry, which is preferable because uniform surface light emission can be obtained.

  The reflector is preferably provided in a sealing can that seals the laminate in the organic electroluminescent element.

[Low refractive index layer]
The organic electroluminescent element of the present invention includes at least a laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode, and a reflector having the convex structure. It is preferable to have a low refractive index layer.
Here, the low refractive index layer is a layer having a refractive index lower than that of the organic light emitting layer, the refractive index is preferably 1.6 or less, more preferably 1.5 or less, and further preferably 1.4 or less. 1.1 or less is particularly preferable, and 1.05 or less is most preferable.
By having the low refractive index layer, the light that is going to travel from the laminate to the low refractive index layer at a high angle is totally reflected at the interface with the low refractive index layer, and returns to the transparent substrate side, thereby improving the light extraction efficiency. Contributes to improvement.

The form of the low refractive index layer is not particularly limited as long as the refractive index condition is satisfied. The low refractive index layer may be a layer made of a low refractive index material (for example, LaF ₃ , BK 7, SiO ₂ , MgF ₂ , NaF, KF, Bi ₂ S ₃ , Na ₅ Al ₃ F _14, etc.). However, it may be a gas layer. Examples of the gas constituting the gas layer include oxygen, nitrogen, carbon dioxide, and air. A vacuum may also be used. The low refractive index layer is preferably a gas layer, more preferably a layer composed of air (air layer) because it has a low refractive index, is easy to manufacture, and does not cost.

  There is no restriction | limiting in particular in the formation method of an air layer, According to the objective, it can select suitably. For example, when a reflector or a diffuse reflector is applied to the back surface (inside) of the sealing can, which will be described later, and the organic layer side of the substrate is sealed, the substrate is sealed so that an air layer with a desired thickness is formed. It can be formed by adjusting the stop position.

  The organic electroluminescent element of the present invention may have two or more light extraction layers, a transparent substrate, a first light extraction layer, a first transparent electrode, an organic light emitting layer, a second transparent electrode, and The organic electroluminescent element which has a laminated body which has a 2nd light extraction layer in this order, and the said reflector may be sufficient. Thereby, the light extraction efficiency can be further improved.

[Second reflector]
The organic electroluminescent element of the present invention preferably has a second reflector different from the reflector (hereinafter referred to as “first reflector” for convenience).
The second reflector is preferably arranged so as to further reflect the light reflected by the first reflector so that it can be easily taken out to the transparent substrate side of the organic electroluminescent element.
In addition, the second reflector is preferably provided so as to contact the first reflector and the transparent substrate (preferably the first reflector and the second reflector are integrated). . Thereby, the 2nd reflector can serve as sealing material mentioned below. In this case, it is also preferable that the second reflector is provided at an acute angle with the transparent substrate.
The shape of the reflective surface of the second reflector is not particularly limited, and may be a flat reflector or may have a convex surface or a concave surface.

[Sealing material]
The organic electroluminescent element of the present invention is preferably sealed with a sealing material in order to prevent deterioration due to moisture, nitrogen oxides, sulfur oxides, ozone and the like.
As a sealing method, the organic electroluminescent device of the present invention is sealed in a sealing can formed of a sealing material, or the transparent substrate of the organic electroluminescent device of the present invention is used as a light extraction layer and a first transparent electrode. , An organic layer including at least one organic light emitting layer, and larger than the second transparent electrode (in a plan view in the stacking direction of the stacked body, the transparent substrate is a light extraction layer, the first transparent electrode, and the organic layer) And the second transparent electrode is entirely covered and made larger), the transparent substrate is used as a lid, the space between the transparent substrate and the reflector is sealed with a sealing material, the light extraction layer, the first A transparent electrode, an organic layer including at least one organic light emitting layer, and a method of encapsulating a second transparent electricity.
The material, size, shape, and structure for forming the sealing can are not particularly limited and can be appropriately selected according to the purpose.
There is no restriction | limiting in particular as a material (sealing material) of a sealing can, What is necessary is just to select suitably according to the objective, and the single layer structure or laminated structure which consists of various inorganic compounds or organic compounds may be sufficient. As the inorganic _{compound, SiNx, SiON, SiO 2,} Al 2 O 3, TiO 2 , and examples of the organic compound, silicon-based polymers, epoxy polymers, acrylic polymers, urethane polymers. The thickness of the barrier layer is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably 0.1 to 10 μm, more preferably 0.1 to 5 μm, and more preferably 0.2 to 3 μm. When the thickness of the sealing layer is less than 0.1 μm, the sealing function for preventing the permeation of oxygen and moisture in the atmosphere may be insufficient. When the thickness exceeds 10 μm, the light transmittance decreases and the transparent layer is transparent. When the inorganic material is used as a single layer, there is a possibility that the barrier properties such as cracking due to stress difference and peeling from the adjacent layer may be impaired. As for the optical properties of the sealing layer, the light transmittance is preferably 80% or more, more preferably 85% or more, and still more preferably 90% or more.
There is no restriction | limiting in particular as a formation method of a sealing layer, According to the objective, it can select suitably, For example, CVD method, a vacuum evaporation method, a sputtering method etc. are mentioned.
In the present invention, it is preferable to use a reflective material as the sealing material.
Thereby, since the light reflected by the reflector is not absorbed by the sealing material, the light extraction efficiency is improved.

In a space between the sealing can and the organic electroluminescent element including the first transparent electrode, the second transparent electrode, and the organic layer, a desiccant (a moisture absorbent or an inert liquid) may be sealed. .
The moisture absorbent is not particularly limited and may be appropriately selected depending on the intended purpose. For example, barium oxide, sodium oxide, potassium oxide, calcium oxide, sodium sulfate, calcium sulfate, magnesium sulfate, phosphorus pentoxide, Examples thereof include calcium chloride, magnesium chloride, copper chloride, cesium fluoride, niobium fluoride, calcium bromide, vanadium bromide, molecular sieve, zeolite, and magnesium oxide.
The inert liquid is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include paraffins, liquid paraffins; fluorinated solvents such as perfluoroalkane, perfluoroamine, and perfluoroether; chlorine System solvents, silicone oils and the like.
In particular, it is preferable to install a desiccant between the reflector and the sealing can.
Preferably, the reflector is provided in the sealing can with a cavity between the reflector and the sealing can, and the cavity has a desiccant.

The organic electroluminescent element can be configured as a device capable of displaying in full color.
As a method of making the organic electroluminescent element of a full color type, for example, as described in “Monthly Display”, September 2000, pages 33 to 37, the three primary colors (blue (B), A three-color light emission method in which a layer structure that emits light corresponding to green (G) and red (R) is arranged on a substrate, a white light that divides white light emission by a layer structure for white light emission into three primary colors through a color filter layer And a color conversion method in which blue light emission by a layer structure for blue light emission is converted into red (R) and green (G) through a fluorescent dye layer are known.
In this case, it is preferable to appropriately adjust the laser power and thickness for each pixel of blue (B), green (G), and red (R).
In addition, a planar light source having a desired emission color can be obtained by using a combination of a plurality of layer structures having different emission colors obtained by the above method. For example, a white light-emitting light source combining blue and yellow light-emitting devices, a white light-emitting light source combining blue (B), green (G), and red (R) organic electroluminescent elements, and the like.

  The organic electroluminescent element is, for example, a surface light source, a lighting device, a computer, an on-vehicle display, an outdoor display, a household device, a commercial device, a household appliance, a traffic display, a clock display, a calendar display. In addition, it can be suitably used in various fields including luminescent screens, acoustic devices and the like.

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

<Estimation of light extraction efficiency by simulation>
The following model was simulated using commercially available ray tracing software (ZEMAX Development Corporation product ZEMAX-EE) using the following model.
The improvement factor of the light extraction efficiency and the light extraction efficiency of each organic electroluminescent element is defined by the following equation.
Light extraction efficiency = light energy emitted to the front air (light extraction side) on the transparent substrate side / light energy emitted from the organic light emitting layer magnification = light extraction efficiency of the implementation element / light extraction efficiency of the reference element 1

1. Reference element 1 (calculation model 1)
As shown in FIG. 13, the calculation model 1 used for the simulation is “air / transparent substrate (BK7, manufactured by OHARA, refractive index (n) = 1.5, attenuation coefficient k = 0, thickness 1 mm) / transparent substrate side. Organic light emitting part including transparent electrode and organic light emitting layer (refractive index (n) = 1.8, absorptance 10%, thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded part in FIG. 13)) / Ag This is an organic EL element composed of a laminate of “reflecting electrode (refractive index (n) = 0.18, attenuation coefficient k = 3.4, thickness 100 nm)”.
The element size is a square of 50 mm × 50 mm. That is, in a plan view in the stacking direction of the stacked body, the shape of the organic light emitting layer is a square, and the length W of the side of the square is 50 mm.
The structure of the organic light emitting part including the transparent electrode on the transparent substrate side is “transparent electrode / hole injection layer and transport layer / organic light emitting layer / electron injection layer and transport layer”.

Literature PONEER R & D Vol. 11 No. According to 1, pp21-28, the refractive index n of the light emitting layer is 1.7 to 1.85. Moreover, a transparent electrode often used, tin-doped indium oxide (ITO) (refractive index (n) = 2.0), ZnO (refractive index (n) = 1.95), SnO ₂ (refractive index (n) = 2.0), In ₂ O ₃ (refractive index (n) = 1.9 to 2.0), and TiO ₂ (refractive index (n) = 1.90) have a refractive index larger than the refractive index of the organic layer. Since the total reflection between the light emitting layer and the air is not affected, the refractive index of the organic light emitting part including the transparent electrode is set to 1.8, and the light emitted from the organic light emitting layer is stacked on the organic light emitting element. Radiates through the body and into the air. Since the organic material constituting the organic light-emitting element has an absorption characteristic for light, when light passes through the organic layer, it is absorbed depending on the attenuation coefficient of the organic material. In addition, there is light reflected inside the organic light emitting device (reflector side) due to a difference in refractive index between the organic light emitting device and air. The light reflected inside the organic light emitting element is reflected again to the light extraction side by the reflective electrode or reflector, and radiates to the air through the organic layer. Each time light passes through the organic layer, it is absorbed depending on the attenuation coefficient of the organic material. Here, the absorptance is 10% every time light passes through the organic layer.

The light distribution of the light emitted from the organic light emitting portion to the transparent substrate (within the refractive index (n) = 1.8) is a Lambertian distribution.
As the organic electroluminescent element, one having the following structure disclosed in Vol 459/14 May 2009 / doi: 10.1038 / nature08003 was used.

Glass (OHARA S-LAH53, refractive index n = 1.8) / ITO (thickness 90 nm) / MeO-TPD: NDP-2 (thickness 45 nm) / NPB (thickness 10 nm) / TCTA: Ir (MDQ) ₂ (acac) (Thickness 6 nm) / TCTA (Thickness 2 nm) / TPBi: FIrpic (4 nm) / TPBi (Thickness 2 nm) / TPBi: Ir (ppy) ₃ / TPBi (10 nm) / Bphen: Cs (Thickness 25 nm) / Ag (Thickness 100 nm)

Note that, as described in paragraph [0002] of Japanese Patent Application Laid-Open No. 2008-70198, the light distribution of light emitted from the light emitting layer and emitted into the transparent substrate is assumed to be a Lambertian distribution.
The light extraction efficiency when the calculation model 1 was simulated was about 32%. From this, the magnification of the light extraction efficiency simulated for each calculation model is the magnification with respect to this light extraction efficiency.

2. Simulation of relationship between air gap D and light extraction efficiency (calculation model 2)
A laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and provided on the second transparent electrode side with respect to the transparent substrate of the laminate. Assuming an organic electroluminescent element (a schematic diagram of the element is shown in FIG. 14) having a planar reflector made of silver, the maximum distance (air gap) D between the laminate and the reflector And the light extraction efficiency was estimated.

The configuration of the calculation model 2 is as follows.
Air / transparent substrate (refractive index n = 1.5, attenuation coefficient k = 0, thickness 1 mm) / light extraction layer (fine particle diffusion scattering film. Binder polymer refractive index nb = 1.8, attenuation coefficient k = 0. Cross-linking) Average particle diameter of acrylic particles φ = 1.5 μm, refractive index np = 1.49, attenuation coefficient k = 0, fine particle volume filling rate 50%, scattering film thickness 5 μm) / including transparent electrode and organic light emitting layer Organic light emitting part (refractive index n = 1.8, absorptance: 10%, film thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded area in FIG. 14)) / air layer (refractive index n = 1.0, Attenuation coefficient k = 0, gap distance D) / Ag reflector (refractive index n = 0.18, attenuation coefficient k = 3.4)
Here, it is assumed that the configuration of the organic light emitting unit including the transparent electrode is “transparent electrode / hole injection layer and transport layer / organic light emitting layer / electron injection layer and transport layer / transparent electrode”.
The light extraction layer is a fine particle diffusion scattering film composed of fine particles diffused into the high refractive index polymer. As a high refractive index polymer, high refractive index nanoparticles (TiO ₂ , refractive index n = 2.6, average particle size of 100 nm or less) are appropriately dispersed in urethane (refractive index n = 1.5), and refractive index nb. = 1.8 was used.
The fine particles were crosslinked acrylic particles having an average particle diameter of φ1.5 μm (refractive index n = 1.49, attenuation coefficient k = 0).
The organic light emitting layer was formed to have a square shape in plan view in the stacking direction of the stacked body, and the side length of the square was set to W.
For the calculation model 2, a simulation was performed using “air gap D / side length W of the organic light emitting layer” as a parameter, and the magnification of the light extraction efficiency with respect to the light extraction efficiency of the calculation model 1 was obtained.

3. Effect of improving the light extraction efficiency by the convex structure reflector, single-surface light extraction layer (calculation model 3)
A laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the laminate on the second transparent electrode side with respect to the transparent substrate of the laminate The simulation was performed assuming an organic electroluminescent element (a schematic diagram of the element is shown in FIG. 15) having a spherical reflector with a radius of curvature R provided on the surface and spaced from the body.
The element of FIG. 15 includes a laminated body having an organic light emitting unit 20 including a transparent substrate 1, a light extraction layer 2, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the organic light emitting unit 20 And a reflector 6 having a spherical surface with a radius of curvature R, which is provided with a gap therebetween.
The configuration of the calculation model 3 is as follows.
Air / transparent substrate (refractive index n = 1.5, attenuation coefficient k = 0, thickness 1 mm) / light extraction layer (fine particle diffusion scattering film. Binder polymer refractive index nb = 1.8, attenuation coefficient k = 0. Cross-linking) Average particle diameter of acrylic particles φ = 1.5 μm, refractive index np = 1.49, attenuation coefficient k = 0, fine particle volume filling rate 50%, scattering film thickness 5 μm) / including transparent electrode and organic light emitting layer Organic light emitting part (refractive index n = 1.8, absorptance: 10%, film thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded area in FIG. 15)) / air layer (refractive index n = 1.0, Spherical Ag reflector having attenuation coefficient k = 0, gap distance D / surface of curvature radius R (refractive index n = 0.18, attenuation coefficient k = 3.4)
The organic light emitting layer was formed to have a square shape in plan view in the stacking direction of the stacked body, and the side length of the square was set to W.
In addition, the center of the reflector overlaps the center of the organic light emitting layer in a plan view in the stacking direction of the stack.
For calculation model 3, with “air gap D / side length W of organic light emitting layer” and “curvature radius R of spherical reflector / side length W of organic light emitting layer” as parameters, the magnification of light extraction efficiency Sought a relationship.

4). Improvement of light extraction efficiency due to the convex structure of the reflector, double-sided light extraction layer (calculation model 4)
A laminate having a transparent substrate, a first light extraction layer, a first transparent electrode, an organic light emitting layer, a second transparent electrode, and a second light extraction layer in this order, and a second light extraction of the laminate Assuming an organic electroluminescent element (a schematic diagram of the element is shown in FIG. 16) having a spherical reflector with a radius of curvature R provided opposite to the layer and spaced from each other, a simulation was performed. went.
16 includes a transparent substrate 1, a light extraction layer 2, a first transparent electrode, an organic light emitting layer, an organic light emitting unit 20 including a second transparent electrode, and a second light extraction layer 8 in this order. And a reflector 6 having a spherical surface with a radius of curvature R, which is provided opposite to the organic light emitting unit 20 with a space therebetween.
The configuration of the calculation model 4 is as follows.
Air / transparent substrate (refractive index n = 1.5, attenuation coefficient k = 0, thickness 1 mm) / light extraction layer (fine particle diffusion scattering film. Binder polymer refractive index nb = 1.8, attenuation coefficient k = 0. Cross-linking) Average particle diameter of acrylic particles φ = 1.5 μm, refractive index np = 1.49, attenuation coefficient k = 0, fine particle volume filling rate 50%, scattering film thickness 5 μm) / including transparent electrode and organic light emitting layer Organic light emitting part (refractive index n = 1.8, absorptance: 10%, film thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded area in FIG. 16)) / second light extraction layer (fine particle diffusion scattering film Refractive index nb = 1.8 of binder polymer, attenuation coefficient k = 0, average particle diameter φ1.5 μm of crosslinked acrylic particles, refractive index np = 1.49, attenuation coefficient k = 0, volume filling rate of fine particles 50 % Scattering film thickness 5 μm) / air layer (refractive index n = 1.0, k = 0) A spherical Ag reflector having a gap distance D / surface of curvature radius R (refractive index n = 0.18, attenuation coefficient k = 3.4)
The organic light emitting layer was formed to have a square shape in plan view in the stacking direction of the stacked body, and the side length of the square was set to W.
In addition, the center of the reflector overlaps the center of the organic light emitting layer in a plan view in the stacking direction of the stack.
The calculation model 4 was simulated in the same manner as the calculation model 3 using “air gap D / side length W of the organic light emitting layer” and “curvature radius R of the convex surface structure of the reflector” as parameters. The magnification of the light extraction efficiency with respect to the light extraction efficiency was determined.

5. Improved light extraction efficiency due to the refractive index of the low refractive index layer, convex structure reflector (calculation model 5)
A laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the laminate on the second transparent electrode side with respect to the transparent substrate of the laminate An organic electroluminescent element (an element of the element) having a low-refractive-index layer between the laminated body and the reflector, the surface of the reflector having a spherical radius of curvature R provided with a distance from the body A simulation was performed assuming a schematic diagram shown in FIG.
The element of FIG. 19 includes a laminated body having an organic light emitting unit 20 including a transparent substrate 1, a light extraction layer 2, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the organic light emitting unit 20 And a reflector 6 having a spherical surface with a radius of curvature R, which is provided with a gap therebetween, and a low refractive index layer 22 between the laminate and the reflector 6.
The configuration of the calculation model 5 is as follows.
Air / transparent substrate (refractive index n = 1.5, attenuation coefficient k = 0, thickness 1 mm) / light extraction layer (fine particle diffusion scattering film. Binder polymer refractive index nb = 1.8, attenuation coefficient k = 0. Cross-linking) Average particle diameter of acrylic particles φ = 1.5 μm, refractive index np = 1.49, attenuation coefficient k = 0, volume filling rate of fine particles 50%, scattering film thickness 5 μm) / organic light emitting part including transparent electrode ( Refractive index n = 1.8, absorptance 10%, film thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded area in FIG. 19) / low refractive index layer (refractive index n = 1.0 to 1.8) , Attenuation coefficient k = 0, gap distance D = W = 50 mm) / spherical Ag reflector having a curvature radius R on the surface (refractive index n = 0.18, attenuation coefficient k = 3.4, convex curvature R = 0) .75W)
The organic light emitting layer was formed so as to have a square shape in plan view in the stacking direction of the stacked body, and the side length of the square was W (= 50 mm).
In addition, the center of the reflector overlaps the center of the organic light emitting layer in a plan view in the stacking direction of the stack.
For calculation model 5, the light extraction efficiency was calculated using the refractive index of the low refractive index layer as a parameter. A simulation was performed to determine the ratio of the light extraction efficiency to the light extraction efficiency of the calculation model 1.

6). Improvement of light extraction efficiency due to the refractive index of the low refractive index layer, planar reflector (calculation model 6)
A laminate having a transparent substrate, a light extraction layer, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the laminate on the second transparent electrode side with respect to the transparent substrate of the laminate An organic electroluminescent device having a planar reflector disposed at a distance from the body and having a low refractive index layer between the laminate and the reflector (a schematic diagram of the device is shown in FIG. 20) The simulation was performed on the assumption.
The element of FIG. 20 includes a laminated body having an organic light emitting unit 20 including a transparent substrate 1, a light extraction layer 2, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order, and the organic light emitting unit 20 And a planar reflector 6r provided at intervals, and a low refractive index layer is provided between the laminate and the reflector 6r.
The configuration of the calculation model 6 is as follows.
Air / transparent substrate (refractive index n = 1.5, attenuation coefficient k = 0, thickness 1 mm) / light extraction layer (fine particle diffusion scattering film. Binder polymer refractive index nb = 1.8, attenuation coefficient k = 0. Cross-linking) Average particle diameter of acrylic particles φ = 1.5 μm, refractive index np = 1.49, attenuation coefficient k = 0, volume filling rate of fine particles 50%, scattering film thickness 5 μm) / organic light emitting part including transparent electrode ( Refractive index n = 1.8, absorptance 10%, film thickness 2 μm, light emitting area is 2 mm × 2 mm square (shaded area in FIG. 20) / low refractive index layer (refractive index n = 1.0 to 1.8) , Attenuation coefficient k = 0, gap distance D = W = 50 mm) / planar Ag reflector (refractive index n = 0.18, attenuation coefficient k = 3.4)
The organic light emitting layer was formed so as to have a square shape in plan view in the stacking direction of the stacked body, and the side length of the square was W (= 50 mm).
For calculation model 6, the light extraction efficiency was calculated using the refractive index of the low refractive index layer as a parameter. A simulation was performed to determine the ratio of the light extraction efficiency to the light extraction efficiency of the calculation model 1.

<Simulation results>
In FIG. 17, for calculation model 2 to calculation model 4, with respect to air gap D / side length W of the element as a parameter, a planar Ag reflector and a spherical Ag reflector element whose surface has a curvature radius R are shown. The results of improving the light extraction efficiency are summarized. In the case of a planar Ag reflector, the light extraction efficiency of the element model was determined for each air gap D. In the case where the convex surface is a spherical Ag reflector (layer) having a curvature radius R, the curvature radius R was changed, and the light extraction efficiency was determined with the optimum curvature radius R of each air gap D. More specifically, with respect to calculation model 3 and calculation model 4, when the air gap is D, the curvature radius R of the convex surface is changed, the light extraction efficiency of the element is calculated, and the curvature that maximizes the light extraction efficiency is obtained. The radius R was determined, and the optimized light extraction efficiency of the air gap D at the curvature radius R was determined.
It has been found that if there is an air layer and the distance D of the air gap is small with respect to W, the improvement of the light extraction efficiency is insufficient. Even in each model of a planar Ag reflector and a spherical Ag reflector element having a radius of curvature R, when the air gap distance D is less than 0.5 times the organic EL element side length W, the light extraction efficiency is improved. The improvement is insufficient, and when the distance D of the air gap becomes 0.5 times or more of the organic EL element side length W, the improvement factor of the light extraction efficiency becomes stable.
When the distance D of the air gap is smaller than 0.25 times the side length W of the organic EL element, the improvement of the light extraction efficiency of the organic EL element having the convex structure reflector (layer) configuration is not much different from that of the planar reflector. Or lower than the planar reflector configuration. However, when the distance D of the air gap is 0.25 times or more of the organic EL element side length W, the light extraction efficiency improvement factor of the spherical reflector whose surface has a curvature radius R becomes larger than that of the planar reflector. When the distance D of the air gap is greater than 0.5 times the side length W of the organic EL element, the difference between the improvement factor of the light extraction efficiency of the reflector having the convex structure and the flat reflector is stabilized.
In FIG. 18, as an example, for calculation model 3, when the surface has a radius of curvature R / element side length W of a spherical reflector having a radius of curvature R, the air gap distance D is changed. The range of radius of curvature R / side length W of the element optimized is shown. More specifically, when the radius of curvature R of the convex surface is used as a parameter, the calculation model 3 is optimized by changing the air gap D, and the optimized light extraction efficiency of the element at the optimum D is calculated. The curvature radius R of the spherical reflector whose surface has a curvature radius R / side length W of the element is preferably 0.1 to 3, and more preferably 0.2 to 1.5.
FIG. 21 shows the results of calculation models 5 and 6. More specifically, with respect to calculation models 5 and 6, when the refractive index of the low refractive index layer was used as a parameter, the relationship between the magnification of light extraction efficiency was shown.
From FIG. 21, when the refractive index of the low refractive index layer is 1.6 or less, the magnification of light extraction efficiency is improved, and the refractive index is more preferably 1.3 or less, and the low refractive index layer is an air layer. It can be seen that this is most preferable.
Further, FIG. 21 shows that the reflector is more effective when the reflector has a spherical convex structure than when the reflector is a planar reflector.

<Example of production of organic electroluminescence device>
Hereinafter, although the example of preparation of the organic electroluminescent element of this invention is shown concretely, these are examples and this invention is not limited to these specific examples.

[Example 1]
FIG. 7 shows a schematic diagram of the organic electroluminescent element of Example 1. The organic electroluminescent device 100 of FIG. 7 includes an organic light emitting unit 20 including a transparent substrate 1, a light extraction layer 2, a first transparent electrode, an organic light emitting layer, and a second transparent electrode, a laminated body in this order, an organic And a reflector 6 provided at an interval so as to face the light emitting unit 20. The surface of the reflector 6 on the organic light emitting unit 20 side has one point where the distance between the reflector 6 and the organic light emitting unit 20 is the shortest, and the distance between the reflector 6 and the organic light emitting unit 20 increases. It has a shape in which the distance increases monotonously.
In plan view from the stacking direction of the stacked body in FIG. 7, the reflector 6 covers the entire organic light emitting layer.
The organic electroluminescent element of FIG. 7 has a second reflector 7 different from the reflector 6. The second reflector 7 can further reflect the light reflected by the reflector 6, and can improve the light extraction efficiency even if the size of the organic electroluminescent element is reduced. Contribute. The second reflector 7 is a flat reflector. The second reflector 7 is provided in contact with the transparent substrate 1 and the reflector 6. Since the laminate is sealed with the transparent substrate 1, the reflector 6, and the second reflector 7, entry of moisture and the like from the outside can be prevented.
In FIG. 7, the reflector 6 and the second reflector 7 are separated by a dotted line, but this dotted line is shown for convenience, and actually the reflector 6 and the second reflector 7 May be integrated. The same applies to FIGS.

[Example 2]
FIG. 8 shows a schematic diagram of the organic electroluminescent element of Example 2. The organic electroluminescent element 100 of FIG. 8 is obtained by adding a second light extraction layer 8 to the reflector 6 side of the organic light emitting unit 20 in the organic electroluminescent element of Example 1.

[Example 3]
FIG. 9 shows a schematic diagram of an organic electroluminescent element of Example 3. The organic electroluminescent device 100 of FIG. 9 is the same as the organic electroluminescent device of Example 1, except that the reflector 6 is formed inside the sealing can 9 and the transparent substrate 1 and the sealing can 9 are disposed in contact with each other. The laminate can be sealed to prevent entry of moisture and the like from the outside.
The reflector 6 is formed so as to have a cavity between the bottom of the sealing can 9 and a desiccant is enclosed in the cavity. By encapsulating the desiccant between the reflector 6 and the sealing can 9, light absorption and optical path obstruction by the desiccant can be avoided.

[Example 4]
FIG. 10 shows a schematic diagram of an organic electroluminescent element of Example 4. The organic electroluminescent element 100 of FIG. 10 is obtained by adding a second light extraction layer 8 to the reflector 6 side of the organic light emitting unit 20 in the organic electroluminescent element of Example 3.

[Example 5]
FIG. 11 is a schematic view of the organic electroluminescent element of Example 5. The organic electroluminescent device 100 of FIG. 11 is the same as the organic electroluminescent device of Example 1, except that the second reflector 7 is arranged at an acute angle with the transparent substrate 1 (so as to form an obtuse angle with the reflector 6). Arranged). By disposing the second reflector 7 in this way, the amount of light reflected to the transparent substrate 1 side can be increased, which contributes to improvement of light extraction efficiency.

[Example 6]
FIG. 12 shows a schematic diagram of an organic electroluminescent element of Example 6. The organic electroluminescent device 100 of FIG. 12 is obtained by adding a second light extraction layer 8 to the reflector 6 side of the organic light emitting unit 20 in the organic electroluminescent device of Example 5.

  Hereinafter, a specific method for manufacturing each member will be described.

(Create light extraction layer)
-Preparation of coating composition for forming light extraction layer 11.2 g of resin material (acrylate compound “Ogsol EA-0200” (manufactured by Osaka Gas Chemical Co., Ltd.)) and high refractive index inorganic filler (TiO ₂ dispersion HTD-760) (Taika Co., Ltd.) 40 g was mixed with 42 g of toluene, dissolved by stirring with a roller mixer and a stirrer, and TiO ₂ was dispersed by ultrasonic waves (sonifier) to obtain a high refractive index resin.
14.8 g of light diffusion particles (cross-linked acrylic particles having an average diameter of 1.5 μm, refractive index of 1.49, material name “EX-150”) 14.8 g were added to 93 g of the obtained high refractive index resin while stirring with a stirrer. The light diffusing particles were sufficiently dispersed in a high refractive index resin with ultrasonic waves, and further stirred well with a stirrer. Subsequently, 2 wt% of a polymerization initiator (IRGACURE819, manufactured by Ciba) was added to the resin in an environment where light with a wavelength of 450 nm or less was cut, and the mixture was sufficiently stirred to contain light diffusing particles in the resin film. A coating composition for forming a resin film having a rate of 30% by volume was obtained.

-Film formation of light extraction layer The coating composition for forming the light extraction layer was applied onto the substrate with an edge coater to form a light extraction layer with a thickness of 2 to 10 µm.

(Glass substrate surface treatment)
The glass substrate is subjected to a silane coupling treatment to enhance the adhesion between the light extraction layer and the glass.

(Transparent electrode and organic layer deposition)
On the light extraction layer formed on the substrate, 100 nm of ITO is formed using a sputtering device, and then HAT-CN is formed to 10 nm, 2-TNATA (99.8%) and F4-TCNQ (on a vacuum evaporation device). 0.2%) was vapor-deposited at 160 nm, NPD was vapor-deposited at 10 nm, mCP (60%) and material A (40%) were vapor-deposited at 30 nm, and 40 nm of BAlq was further laminated to obtain an organic layer. . Furthermore, 1 nm of LiF was deposited and 0.5 nm of aluminum was deposited as an electrode. Thereafter, ITO is deposited to a thickness of 100 nm.

(Production and sealing of reflector)
1. Sealed package with convex surface (Examples 1, 2, 5, 6)
As a method for forming a desired convex structure in a sealed package, MIM method: metal powder injection molding method) / Metal Injection Molding is well known.
A sealed package having a convex reflecting mirror at the bottom can be obtained by forming a convex shape at the bottom using the MIM method and then coating a metal with high reflectivity (such as Al) after forming the package. A reflector having a desired structure can be obtained by mounting an organic electroluminescent element on this package.

2. When a desiccant is sealed in the convex part (Examples 3 and 4)
In the above method 1, the desiccant cannot be enclosed in the convex portion. In the case of this configuration, a reflection mirror member is formed by coating the convex side with a metal (Al or the like) having a high reflectance after forming a convex portion having a dent by resin injection molding. A package having a convex mirror with a desiccant inserted therein can be obtained by inserting a desiccant into the recess when the reflecting mirror is bonded and fixed to the package. A desired structure can be obtained by mounting an organic electroluminescent element on this package.

-Fabrication of organic electroluminescence device-
A glass substrate (Corning, Eagle XG, refractive index 1.51) is placed in a washing container, ultrasonically washed in a neutral detergent, then ultrasonically washed in pure water, and heated and dried at 120 ° C. for 120 minutes. went. The light extraction layer prepared above was attached to one surface of the substrate from the adhesive layer side.

Next, an ITO (Indium Tin Oxide) film was formed on the light extraction sheet attached to the glass substrate so as to have a thickness of 100 nm by a sputtering method (a conductive diffusion layer can be substituted for ITO).
Next, a HAT-CN layer was deposited on the ITO by 10 nm. Further, 4,4 ′, 4 ″ -tris (N, N- (2-naphthyl) -phenylamino) triphenylamine (2-TNATA) represented by the following structural formula is represented by F4 represented by the following structural formula. -A hole injection layer doped with 0.3% by mass of TCNQ was co-evaporated to a thickness of 150 nm.

Next, α-NPD (Bis [N- (1-naphthyl) -N-phenyl] benzidine)) is formed as a hole transport layer on the hole injection layer by a vacuum deposition method so as to have a thickness of 7 nm. did.
Next, an organic material A represented by the following structural formula was vacuum-deposited on the hole transport layer to form a second hole transport layer having a thickness of 3 nm.

  Next, an organic material B represented by the following structural formula as a host material on the second hole transport layer, and a phosphorescent light emitting material of 40 mass% with respect to the organic material B is represented by the following structural formula. The light emitting layer doped with the light emitting material A was vacuum evaporated to a thickness of 30 nm.

  Next, BAlq (Bis- (2-methyl-8-quinolinolato) -4- (phenyl-phenolate) -aluminum (III)) represented by the following structural formula is formed as an electron transport layer on the white light-emitting layer with a thickness of 39 nm. Vacuum deposition was performed so that

  Next, on the electron transport layer, BCP (2,9-dimethyl-4,7-diphenyl-1,10-phenanthroline) represented by the following structural formula is used as an electron injection layer so that the thickness is 1 nm. did.

Next, LiF having a thickness of 1 nm was formed on the electron injection layer as a buffer layer, and ITO was formed thereon with a thickness of 100 nm in the same manner as described above to form a second transparent electrode. Moreover, in order to implement | achieve the function as a cathode, the thin film of 1 nm-10 nm Al or Ag can also be vapor-deposited on the said buffer layer or a 2nd transparent electrode.
The produced laminated body is moved from a vacuum to a room under a nitrogen atmosphere and sealed with a sealing can. A hygroscopic material was previously pasted inside the sealing can. Thus, organic electroluminescent devices of (Examples 1 to 6) were produced.

DESCRIPTION OF SYMBOLS 1 Transparent substrate 2 Light extraction layer 3 1st transparent electrode 4 Organic light emitting layer 5 Second transparent electrode 6, 6r Reflector 7 Second reflector 8 Second light extraction layer 9 Sealing can 10 Laminate 20 Organic Light emitting part (including transparent electrode and organic light emitting layer)
22 Low Refractive Index Layer 100 Organic Electroluminescent Element a to h Ray P Center Point

Claims (19)

A laminate having a transparent substrate, a light extraction layer for diffusing light generated in the organic light emitting layer toward the transparent substrate, a first transparent electrode, an organic light emitting layer, and a second transparent electrode in this order;
A reflector that reflects the light generated in the organic light emitting layer provided on the side of the laminate that has the second transparent electrode with respect to the transparent substrate and is spaced from the laminate;
The surface on the laminate side of the reflector has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate becomes monotonous as the distance from the point or line increases. Has an increasing shape,
The organic electroluminescent element which the said reflector has covered the whole said organic light emitting layer in planar view in the lamination direction of the said laminated body.   The organic electroluminescent element according to claim 1, wherein a low refractive index layer having a refractive index lower than that of the organic light emitting layer is present between the laminate and the reflector.   The organic electroluminescent element according to claim 2, wherein the low refractive index layer is an air layer.   The organic electroluminescent element according to claim 1, wherein the reflector has a spherical shape, a conical shape, a pyramid shape, or a triangular prism shape.   The surface of the reflector on the laminate side has one point or line with the shortest distance between the reflector and the laminate, and the distance between the reflector and the laminate becomes continuous as the distance from the point or line increases. The organic electroluminescent element according to claim 1, wherein the organic electroluminescent element has a shape that increases rapidly. The area of the organic light emitting layer on the reflector side is S,
When the maximum value of the distance between the surface of the laminate and the reflector is D,
The organic electroluminescent element according to claim 1, wherein √S and D satisfy the following formula (1).
0.3 ≦ D / √S Formula (1) In plan view in the stacking direction of the stacked body, the shape of the organic light emitting layer is a square, and the side length of the square is W,
When the maximum value of the distance between the surface of the laminate and the reflector is D,
The organic electroluminescent element according to any one of claims 1 to 6, wherein W and D satisfy the following formula (2).
0.5 ≦ D / W Formula (2)   The organic electroluminescent element of any one of Claims 1-7 whose surface of the said reflector is spherical shape. In plan view in the stacking direction of the stacked body, the shape of the organic light emitting layer is a square, and the side length of the square is W,
When the radius of curvature of the surface of the reflector is R,
The organic electroluminescent element according to claim 8, wherein W and R satisfy the following formula (3).
0.1 ≦ R / W ≦ 3 Formula (3)   The organic electroluminescent element according to claim 1, wherein the reflector is made of a metal material or a diffuse reflector having a reflectance of 90% or more.   The organic electroluminescent element according to claim 1, wherein the light extraction layer is a fine particle diffusion layer containing scattering fine particles.   The organic electroluminescent element according to claim 1, further comprising a second reflector that further reflects the light reflected by the reflector toward the transparent substrate.   The organic electroluminescent element according to claim 12, wherein the second reflector is provided in contact with the reflector and the transparent substrate.   The organic electroluminescent element according to claim 13, wherein the second reflector is provided so as to form an acute angle with the transparent substrate.   The organic electroluminescent element of any one of Claims 1-14 with which the said reflector is provided in the sealing can which seals the said laminated body.   The organic electroluminescent element according to claim 15, wherein the reflector is provided in the sealing can with a cavity between the reflector and the sealing can, and the desiccant is provided in the cavity.   The organic electroluminescent element according to any one of claims 1 to 16, wherein a second light extraction layer is further provided on the reflector side of the second transparent electrode.   The surface light source containing the organic electroluminescent element of any one of Claims 1-17.   The illuminating device containing the organic electroluminescent element of any one of Claims 1-17.

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