JP6269065B2 - Organic electroluminescence light source device - Google Patents

Description

  The present invention relates to an organic electroluminescence (hereinafter sometimes abbreviated as “organic EL”) light source device.

  An organic EL light source device is a device that has a plurality of layers of electrodes and an organic light emitting layer provided therebetween, and electrically emits light by energizing the electrodes. An organic EL light source device is used as a display element in place of a liquid crystal cell, and also takes advantage of its high luminous efficiency, low voltage drive, light weight, low cost, etc., flat illumination, a backlight for a liquid crystal display device, etc. Use as a surface light source is also being studied.

  When the organic EL light source device is used as a surface light source, it is a problem to extract useful light from the organic EL light source device with high efficiency. For example, although the light-emitting layer itself of the organic EL light source device has high luminous efficiency, the light amount is reduced due to interference in the layer until it emits light through the laminated structure that constitutes the device. It is required to reduce such light loss as much as possible.

  As a method for increasing the light extraction efficiency, for example, in Patent Document 1, the luminance in the front direction (0 °) of the element is suppressed and the luminance at an angle of 50 to 70 ° is increased, thereby increasing the overall luminance. It is disclosed.

  A technique using a combination of a transparent electrode and a reflective layer instead of providing a reflective electrode is also known (Patent Document 2).

Japanese Patent Application Laid-Open No. 2004-296423 (corresponding US publication US Patent Application Publication No. 2004/195862) International Publication No. 2009/131019 (corresponding US Publication No. 2011/050082 specification)

  However, the light source device is required to further improve the light extraction efficiency.

  Moreover, in patent document 2, as a structure for reflecting the light radiate | emitted on the opposite side to the light-projection surface among the light generate | occur | produced in the light emitting layer, a transparent electrode and a reflective layer are used instead of the conventionally used reflective electrode. Is used in combination. Since the reflective layer can be easily manufactured with a higher reflectance and lower cost than the reflective electrode, the configuration disclosed in Patent Document 2 is advantageous in increasing the light extraction efficiency. However, since the transparent electrode generally has a higher resistance than the reflective electrode, the in-plane voltage uniformity tends to be impaired. Therefore, it is difficult to obtain a light source device that has a large light source device area and emits light uniformly.

  Accordingly, an object of the present invention is to provide an organic EL light source device that has high light extraction efficiency and can easily increase the area.

In order to solve the above-mentioned problem, the present inventor has studied, as a result, instead of the reflective electrode commonly used in the prior art, as described in Patent Document 2, a reflective layer and a transparent electrode are used instead of the reflective electrode. Instead of using a combination of the above, it was conceived to use a combination of a reflective electrode and a reflective layer. That is, the inventor of the present application has a mode in which only a part of the light emitted from the light emitting layer in the direction opposite to the light emitting surface is reflected by the reflective electrode, and the rest is reflected by the reflective layer having a high reflectance. I thought of adopting it.
By adopting such an aspect, a reflective electrode whose resistance can be reduced more easily than a transparent electrode is used, and a large proportion of light is reflected by the reflective layer. As a result, uniform light emission over a large area is possible, and the light extraction efficiency can be improved. The present invention has been completed based on this finding.
Therefore, according to the present invention, the following [1] to [6] are provided.

[1] An organic electroluminescence light source device having a transparent electrode layer, a light emitting layer, a reflective electrode layer, and a reflective layer in this order from the light exit surface side,
The reflective electrode layer has a through hole,
An organic electroluminescence light source device, wherein the reflectance of the reflective layer is greater than the reflectance of the surface of the reflective electrode layer on the light emitting layer side.
[2] The organic electroluminescence light source device according to [1], wherein the reflective layer or the additional layer has a diffusing element that diffuses light.
[3] The organic electroluminescence light source device according to [2], wherein the diffusion element has a light diffusion layer or a concavo-convex structure layer provided on the light exit surface side of the transparent electrode layer. .
[4] The organic electroluminescence light source device according to [2] or [3], wherein the diffusion layer has the reflection layer that is a white scattering reflection layer.
[5] The organic electroluminescence light source device according to any one of [1] to [4], wherein the organic electroluminescence light source device further includes a gas layer between the reflective layer and the reflective electrode layer.
[6] The organic electroluminescence light source device according to any one of [1] to [5],
A light-emitting surface structure layer that is provided in contact with the surface of the transparent electrode layer opposite to the light-emitting layer and that defines a light-emitting surface of the device;
The reflective electrode layer has a periodic or grid shape having periodicity,
The organic electroluminescence light source device wherein the periodic pitch is equal to or less than the thickness of the light-emitting surface structure layer.

  The light source device of the present invention is useful as a light source for a backlight of a liquid crystal display device, an illumination device, and the like because it has a high light extraction efficiency and can be a device that emits light uniformly over a large area.

FIG. 1 is an elevational sectional view schematically showing a layer configuration of an organic EL light source device according to the first embodiment of the present invention. FIG. 2 is a perspective view schematically showing only the reflective electrode layer 112 and the reflective layer 131 of the light source device 100 according to the first embodiment. FIG. 3 is a perspective view schematically showing only the concavo-convex structure layer 141 of the light source device 100 according to the first embodiment. FIG. 4 is an elevational sectional view schematically showing a layer configuration of an organic EL light source device according to the second embodiment of the present invention. FIG. 5 is an elevational sectional view schematically showing a layer structure of an organic EL light source device according to the third embodiment of the present invention. FIG. 6 is a perspective view schematically showing another example of the reflective electrode layer and the reflective layer in the organic EL light source device of the present invention. FIG. 7 is an elevational sectional view schematically showing an example of a conventional organic EL light source device studied for comparison in the embodiment of the present application. FIG. 8 is an elevational sectional view schematically showing another example of a conventional organic EL light source device studied for comparison in the embodiment of the present application.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. The present invention is not limited to the embodiments and exemplifications described below, and can be implemented with any modifications without departing from the scope of the claims of the present invention and the equivalents thereof.

〔Overview〕
The organic EL light source device of the present invention includes a transparent electrode layer, a light emitting layer, a reflective electrode layer, and a reflective layer in this order from the light exit surface side. The transparent electrode layer, the light emitting layer, and the reflective electrode layer, and an optional layer between the transparent electrode and the reflective electrode provided as necessary constitute a light emitting element, and energize the transparent electrode layer and the reflective electrode layer. The light emitting layer emits light.
In the present application, the “reflective layer” and the “reflective electrode layer” are separate components, and thus the reflective layer is a layer other than the reflective electrode layer.
In the present application, the light exit surface of the light source device may be simply referred to as “device light exit surface”. The device light exit surface is an interface between the inside of the device and the outside of the device when light is emitted from the light source device to the outside of the device.
The device light exit surface is a surface parallel to the surface of the light emitting layer and parallel to the main surface of the surface light source device. However, when the device light exit surface is defined by a surface having a fine concavo-convex structure, the area of the actual light exit surface is sufficiently larger than that of the concavo-convex structure. Can be recognized as a flat surface. In the present application, unless otherwise specified, it is simply “parallel (or perpendicular) to the device light-emitting surface” to be parallel (or perpendicular) to the device light-emitting surface viewed ignoring the microscopic uneven structure. That's it. In the present application, unless otherwise specified, the surface light source device will be described in a state where the device light-emitting surface is placed so as to be parallel to the horizontal direction and upward. Therefore, in the following description, for example, the “upper” surface of a certain layer constituting the surface light source device is a surface closer to the device light-emitting surface of the layer, and the “lower” surface is the surface of the layer. This is the surface far from the device light exit surface.
In the present application, the fact that each component is “parallel” or “vertical” may include an error within a range that does not impair the effects of the present invention, for example, an error of ± 5 ° from a parallel or vertical angle. May be included.

(First embodiment)
FIG. 1 is an elevational sectional view schematically showing a layer configuration of an organic EL light source device according to the first embodiment of the present invention.
In FIG. 1, a light source device 100 includes a substrate 101, a transparent electrode layer 111 provided on the lower side of the substrate 101, a light emitting layer 121 provided on the lower side of the transparent electrode layer 111, and a lower side of the light emitting layer 121. And a reflective layer 131 provided on the lower side of the light emitting layer 121 and the reflective electrode layer 112. The transparent electrode 111, the light emitting layer 121, and the reflective electrode layer 112 constitute the light emitting element 120.

  The light source device 100 also has a concavo-convex structure layer 141 on the upper side of the substrate 101, and the upper surface 141 U of the concavo-convex structure layer defines the device light exit surface of the light source device 100. Hereinafter, the structure from the device light exit surface to the upper surface of the transparent electrode layer may be referred to as a light exit surface structure layer. In the example of the first embodiment, a structure in which the substrate 101 and the concavo-convex structure layer 141 are combined constitutes the light exit surface structure layer 190. In the present application, the light emitting surface structure layer is a structure from the device light emitting surface to the upper surface of the transparent electrode layer, so that the lower surface of the light emitting surface structure layer is in contact with the transparent electrode layer, while the upper surface thereof. Defines the light exit surface of the device.

  The light source device 100 can further include a sealing member (not shown) on the lower side and the side surface portion of the reflective layer 131 as needed. With this and the substrate 101, the light emitting element 120 can be connected from the outside of the device. It can protect from elements (moisture, oxygen, etc.) that degrade the element.

In the organic EL light source device of the present invention, the reflective electrode layer has a through hole. By combining a reflective electrode layer having a through-hole and a reflective layer, a part of the surface of the entire light source device that reflects light emitted downward from the light emitting layer upwards is the surface of the reflective electrode layer. The surface of the reflective layer occupies the other part of the area.
If it demonstrates with reference to the apparatus 100 of 1st Embodiment, the reflective electrode layer 112 has the through-hole 113. FIG. The through hole 113 penetrates from the upper surface side to the lower surface side. In the through hole 113, the light emitting layer 121 and the reflective layer 131 are in contact. Therefore, of the surface 131U of the reflective layer 131 on the light emitting layer 121 side, the surface 131E in the region in the through hole 113 faces the light emitting layer 121, and the surface 131C in the other region is covered with the reflective electrode layer 112. Yes. The reflective layer 131 is made of a material that specularly reflects incident light with high reflectivity.

  FIG. 2 is a perspective view schematically showing only the reflective electrode layer 112 and the reflective layer 131 of the light source device 100 according to the first embodiment. 1 to 8, orthogonal coordinate axes (X axis, Y axis, and Z axis) correspond to each other. For example, among the orthogonal coordinate axes shown in FIG. 2, the X axis and the Z axis correspond to the coordinate axes X axis and Z axis shown in FIG. As shown in FIG. 2, the through hole 113 of the reflective electrode layer 112 has a square structure, and each side of the square extends in parallel to the X axis direction and the Y axis direction. A large number of through holes 113 are arranged at equal intervals in the X-axis direction and the Y-axis direction. Thereby, the reflective electrode layer 112 has a lattice-like structure composed of a linear structure extending in the X-axis direction and the Y-axis direction. By having such a structure, a part of the device reflecting surface is occupied by the upper surface 112U of the reflecting electrode layer 112, and the other part is occupied by the surface 131E of the reflecting layer 131.

  In the first embodiment, unlike the reflective electrode layer 112, the substrate 101, the transparent electrode layer 111, and the light emitting layer 121 are flat layers extending over the entire region of the device light exit surface. However, since the light emitting layer 121 is in contact with the reflective electrode layer 112 having a through hole, the light emitting layer 121 may have a fine uneven structure that follows the shape of the reflective electrode layer 112 on the lower surface thereof.

  FIG. 3 is a perspective view schematically showing only the concavo-convex structure layer 141 of the light source device 100 according to the first embodiment. As shown in FIG. 3, the upper surface 141 </ b> U of the concavo-convex structure layer 141 has a large number of recesses 142. The recesses 142 have a quadrangular pyramid shape, and are arranged on the upper surface 141U of the concavo-convex structure layer 141 so as to be aligned in the X-axis direction and the Y-axis direction at intervals.

  2 and 3 are schematic diagrams, and only a small number of through holes 113 and recesses 142 are shown. In an actual apparatus, the size of the through holes and the recesses is the area of the light exit surface of the apparatus. Can have a much larger number of through holes and recesses than those illustrated in FIGS. 2 and 3.

In the organic EL light source device of the present invention, the reflectance of the reflective layer is larger than the reflectance of the surface of the reflective electrode layer on the light emitting layer side. Here, the reflectance of the reflective layer is the reflectance of the surface of the reflective layer on the light emitting layer side. When the reflective layer and the reflective electrode layer are in contact, light does not normally reach the interface between the reflective layer and the reflective electrode layer. Therefore, the light emitting layer is formed through the through hole in the surface of the reflective layer on the light emitting layer side. Only the region facing the surface can be considered for the reflectivity of the reflective layer.
This will be described with reference to the example of the apparatus 100 of the first embodiment. The reflectance of the surface 131E in the region in the through hole 113 in the surface 131U of the reflective layer 131 is the reflection of the upper surface 112U of the reflective electrode layer 112. Greater than rate. Light emitted downward from the light emitting layer 121 (light generated downward in the light emitting layer 121 and generated upward in the light emitting layer 121 and emitted to the upper side of the light emitting layer 121. Part of the light reflected at the interface and transmitted through the light emitting layer 121 and emitted to the lower side of the light emitting layer is reflected on the surface 112U of the reflective electrode 112, and the other part is reflected. A part of the upper surface 131U of the layer 131 is reflected with a higher reflectance. The light reflected on the surfaces 131E and 112U travels upward, and at least a part of the light passes through the light emitting layer 121, the transparent electrode 111, the substrate 101, and the concavo-convex structure layer 141, and the device light exit surface (in this example, the upper side of the concavo-convex structure layer). From the surface 141U).

In the organic EL light source device of the present invention, in-plane voltage uniformity can be easily increased by using a reflective electrode instead of a transparent electrode as an electrode on the opposite side of the light emitting layer from the device light-emitting surface. Therefore, it is possible to easily obtain a light source device that has a large light emission area and emits light uniformly. Furthermore, when the reflective electrode layer has a through hole and is combined with a reflective layer having a predetermined reflectance, the light extraction efficiency can be increased.
Specifically describing this feature, the reflective electrode layer generally has both high reflectivity and work function characteristics suitable for the electrode, as well as device fabrication processes, to improve light extraction efficiency. Appropriateness is required, but it is difficult to satisfy them at the same time. Therefore, aluminum is generally used. The reflectance of the aluminum reflective electrode layer is about 85%, and 15% of light is lost for each reflection. Therefore, in the present application, the reflective electrode layer is not provided in the entire region of the device reflection surface, but the reflective electrode layer is provided only in a part of the region, and the reflective layer is provided in the other region. Unlike the reflective electrode, the reflective layer does not require a high work function, and only a high reflectance is required. Therefore, it is possible to easily select a material that is inexpensive and exhibits a reflectance higher than that of the reflective electrode layer, such as 85%. Therefore, in the present invention, it is possible to employ a material having a high work function as the material of the reflective electrode layer and to increase the reflectance of the entire apparatus, and to configure such an aspect from an inexpensive material. it can.

  The ratio of the area occupied by the reflective surface of the reflective electrode layer to the area occupied by the reflective surface of the reflective layer in the area when the area in the light output surface of the apparatus is observed from above the device in a direction perpendicular to the light output surface of the apparatus. Can be appropriately adjusted according to factors such as the reflectance of each layer, the desired light extraction efficiency, and the desired amount of emitted light. Usually, the ratio of the area occupied by the reflective surface of the reflective electrode layer to the total of the area occupied by the reflective surface of the reflective electrode layer and the area occupied by the reflective surface of the reflective layer is preferably 1% or more, and preferably 5% or more. More preferably, it is preferably 50% or less, more preferably 40% or less. By setting the ratio of the area occupied by the reflective surface of the reflective electrode layer to be equal to or higher than the lower limit, it is possible to obtain a high amount of light emitted from the apparatus, while the ratio of the area occupied by the reflective surface of the reflective electrode layer is equal to or lower than the upper limit. Thus, high light extraction efficiency can be obtained.

  The organic EL light source device of the present invention preferably has a diffusing element that diffuses light. Specifically, the reflective layer may also function as a diffusing element, or the light source device may have a diffusing element as an additional layer other than the reflective layer. In the latter case, the diffusing element can be, for example, a light diffusing layer or an uneven structure layer provided on the light exit surface side of the transparent electrode layer. The concavo-convex structure layer is a layer having a concavo-convex structure on one or both of the front surface and the back surface. For example, like the concavo-convex structure layer 141 in the first embodiment, It can be a layer having a large number of recesses, protrusions, or both.

  The organic EL light source device of the present invention can further enhance the light extraction efficiency by having such a diffusing element. This will be described with reference to the device 100 of the first embodiment in FIG. 1. Light emitted upward from the light emitting layer 121 (light generated upward in the light emitting layer 121, and the reflective electrode 112 and the reflective layer 131. At least a part of the reflected light travels upward through the substrate 101 and the concavo-convex structure layer 141. Then, the light exits from the device light exit surface 141U, but the other part does not exit and is reflected by the device light exit surface 141U and returned to the inside of the device. In particular, at the interface between the concavo-convex structure layer 141 and the outside of the device, light whose angle formed by the interface and the light traveling direction is less than the critical angle is totally reflected and returned into the device. In such reflection, when the concavo-convex structure layer 141 has a concavo-convex structure, the reflection direction is diffused, and light is reflected in various directions. The reflected light is reflected by the reflective layer 131 and the reflective electrode 112 and reaches the interface between the concavo-convex structure layer 141 and the outside of the apparatus again. At this time, since the traveling direction of light is diffused by the diffused reflection, the ratio of light that enters the interface at an angle greater than the critical angle and exits from the apparatus increases. Here, in the organic EL light source device of the present invention, the ratio of the light emitted outside the device by the diffusing element (in this example, the concavo-convex structure layer) is obtained by having a reflective layer having a high reflection efficiency and the reflective electrode in combination. The increasing effect can be further enhanced, resulting in a synergistic effect and greatly improving the light extraction efficiency.

(Each component)
The materials and properties of each component of the organic EL light source device of the present invention will be described more specifically below.

(Light emitting element)
In the organic EL light source device of the present invention, the light-emitting layer constituting the light-emitting element is not particularly limited and can be appropriately selected from known ones. By combining the types of layers, light including a predetermined peak wavelength described later can be emitted.
The material constituting the transparent electrode layer and the reflective electrode layer is not particularly limited, and a known material used as an electrode of the organic EL light-emitting element can be appropriately selected, and either one is an anode and the other is a cathode. Can do. In addition to the light emitting layer, the electrode may further include an arbitrary layer such as a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and a gas barrier layer, and these also serve as components of the light emitting element. sell.

Examples of the material for the transparent electrode layer include a metal thin film, ITO, IZO, SnO _{2 and the} like. Examples of the material of the reflective electrode layer include aluminum and MgAg.

Specific layer configurations of the light-emitting element include anode / hole transport layer / light-emitting layer / cathode configuration, anode / hole transport layer / light-emitting layer / electron injection layer / cathode configuration, anode / hole injection layer / Composition of light emitting layer / cathode, anode / hole injection layer / hole transport layer / light emitting layer / electron transport layer / electron injection layer / cathode composition, anode / hole transport layer / light emitting layer / electron injection layer / equipotential Structure of surface forming layer / hole transport layer / light emitting layer / electron injection layer / cathode, anode / hole transport layer / light emitting layer / electron injection layer / charge generation layer / hole transport layer / light emitting layer / electron injection layer / Examples include the configuration of the cathode. The light-emitting element in the organic EL light source device of the present invention can have one or more light-emitting layers between the anode and the cathode, and as the light-emitting layer, a laminate of a plurality of layers having different emission colors, or A certain dye layer may have a mixed layer doped with different dyes. The material of each layer is not particularly limited. For example, examples of the material constituting the light emitting layer include materials such as polyparaphenylene vinylene, polyfluorene, and polyvinyl carbazole. Examples of the hole injection layer and the hole transport layer include phthalocyanine-based, arylamine-based, and polythiophene-based materials. Examples of the electron injection layer and the electron transport layer include aluminum complexes and lithium fluoride. As the equipotential surface forming layer or the charge generation layer, ITO, IZO, the transparent electrode such as SnO _2, or Ag, and metal thin film such as Al.

  The transparent electrode layer, the light emitting layer, the reflective electrode layer, and any other layer constituting the light emitting element can be provided by sequentially laminating them on the substrate. The thickness of each of these layers can be 10 to 1000 nm.

  A method for forming the reflective electrode layer having the through hole is not particularly limited, and a known method for forming a thin film, such as photolithography and mask sputtering, can be used.

  Specifically, the lower limit of the reflectance of the surface on the light emitting layer side of the reflective electrode layer is preferably 75% or more, and more preferably 85% or more. On the other hand, the upper limit may be less than 100%. The reflectance of the reflective electrode layer is preferably higher, but in the present invention, efficient reflection can be achieved by combining a reflective layer having a higher reflectance than the reflective electrode layer.

(Reflective layer)
The material which comprises a reflection layer is not specifically limited, The material which can obtain a predetermined high reflectance can be selected suitably. Examples of the reflective layer that performs specular reflection like the reflective layer 131 of the first embodiment include a dielectric multilayer film, gold, and silver.

  Further, the reflection layer may be a diffuse reflection layer that diffuses and reflects light in addition to the mirror reflection layer (see the second embodiment). As the diffuse reflection layer, a white layer in which incident light is reflected by Lambert scattering can be preferably used. As a material constituting such a white layer, specifically, for example, a polyester film is stretched to generate fine bubbles inside the film, and a white film is formed by reflection scattering (for example, Toray Stock Co., Ltd.) Company name, product name "Lumilar", etc.).

  The reflectance of the reflective layer is higher than that of the reflective electrode layer. Specifically, the lower limit is preferably 90% or more, and more preferably 94% or more. On the other hand, the upper limit can be 100% or less.

(Light emitting surface structure layer: substrate)
As a material constituting the substrate, a substrate that can be normally used as a substrate of an organic EL light emitting element, such as a glass substrate, quartz glass, and a plastic substrate, can be adopted. The thickness of the substrate can be 0.01 to 5 mm.

(Light emitting surface structure layer: uneven structure layer)
The concavo-convex structure layer can be generally formed from a resin composition having a light transmittance suitable for use in an optical member. Examples of the resin constituting the resin composition include thermoplastic resins, thermosetting resins, ultraviolet curable resins, and electron beam curable resins. Among these, thermoplastic resins are preferable because they can be easily deformed by heat, and ultraviolet curable resins have high curability and high efficiency, so that an uneven structure layer can be formed efficiently.

  Examples of the thermoplastic resin include polyester-based, polyacrylate-based, and cycloolefin polymer-based resins. In addition, examples of the ultraviolet curable resin include epoxy resins, acrylic resins, urethane resins, ene / thiol resins, isocyanate resins, and the like. As these resins, those having a plurality of polymerizable functional groups can be preferably used. In addition, the said resin may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

  Especially, as a material for the concavo-convex structure layer, a material having high hardness at the time of curing is preferable from the viewpoint of easily forming the concavo-convex structure and easily obtaining scratch resistance of the concavo-convex structure. Specifically, when a resin layer having a film thickness of 7 μm is formed on a substrate without a concavo-convex structure, a material having a pencil hardness of HB or higher is preferable, and a material of H or higher is more preferable. The material which becomes 2H or more is more preferable.

  A light diffusive material may be used as a material of a layer serving as a layer constituent element of the light emitting surface structure such as the uneven structure layer and the base material. Thereby, the light extraction efficiency by diffusion can be further increased, and the change in color depending on the observation angle can be further reduced.

  Examples of the light diffusing material include a material containing particles, and an alloy resin that diffuses light by mixing two or more kinds of resins. Among these, from the viewpoint that the light diffusibility can be easily adjusted, a material including particles is preferable, and a resin composition including particles is particularly preferable.

  The particles may be transparent or opaque. Examples of the material of the particles include metals and metal compounds, and resins. Examples of the metal compound include metal oxides and nitrides. Specific examples of metals and metal compounds include metals having high reflectivity such as silver and aluminum; metal compounds such as silicon oxide, aluminum oxide, zirconium oxide, silicon nitride, tin-added indium oxide, and titanium oxide. be able to. On the other hand, examples of the resin include methacrylic resin, polyurethane resin, and silicone resin. In addition, the particle | grain material may be used individually by 1 type, and may be used combining two or more types by arbitrary ratios.

The shape of the particles can be, for example, a spherical shape, a cylindrical shape, a needle shape, a cubic shape, a rectangular parallelepiped shape, a pyramid shape, a conical shape, a star shape, or the like.
The particle diameter of the particles is preferably 0.1 μm or more, preferably 10 μm or less, more preferably 5 μm or less. Here, the particle diameter is a 50% particle diameter in an integrated distribution obtained by integrating the volume-based particle amount with the particle diameter as the horizontal axis. The larger the particle size, the larger the content ratio of particles necessary for obtaining the desired effect, and the smaller the particle size, the smaller the content. Therefore, as the particle size is smaller, desired effects such as a reduction in change in color depending on the observation angle and an improvement in light extraction efficiency can be obtained with fewer particles. When the particle shape is other than spherical, the diameter of the sphere having the same volume is used as the particle size.

  In the case where the particles are transparent particles and the particles are contained in the transparent resin, the difference between the refractive index of the particles and the refractive index of the transparent resin is preferably 0.05 to 0.5. More preferably, it is 07-0.5. Here, either the particle or the refractive index of the transparent resin may be larger. If the refractive index of the particles and the transparent resin is too close, the diffusion effect cannot be obtained and the color unevenness may be difficult to be suppressed. Conversely, if the difference is too large, the diffusion becomes large and the color unevenness is suppressed, but light Extraction effect may be reduced.

  The content ratio of the particles is a volume ratio in the total amount of the layer containing the particles, preferably 1% or more, more preferably 5% or more, 80% or less, and more preferably 50% or less. By setting the content ratio of the particles to be equal to or higher than the lower limit, desired effects such as reduction of a change in color depending on the observation angle can be obtained. Moreover, by setting it as this upper limit or less, aggregation of particle | grains can be prevented and particle | grains can be disperse | distributed stably.

  Furthermore, the resin composition may contain arbitrary components as necessary. Examples of the optional component include additives such as phenol-based and amine-based degradation inhibitors; surfactant-based, siloxane-based antistatic agents; triazole-based, 2-hydroxybenzophenone-based light-resistant agents; Can be mentioned.

  The thickness of the concavo-convex structure layer is not particularly limited, but is preferably 1 μm to 70 μm. Further, the thickness of the entire light emitting surface structure layer can be preferably 30 μm or more, more preferably 50 μm or more, and preferably 950 μm or less, more preferably 800 μm or less.

The production of the multilayer structure of the concavo-convex structure layer and the substrate is performed, for example, by preparing a mold such as a mold having a desired shape and transferring the mold to a layer of a material forming the concavo-convex structure layer. Can do. As a more specific method, for example,
(Method 1) Prepare a raw multilayer body having a layer of the resin composition A constituting the substrate and a layer of the resin composition B constituting the concavo-convex structure layer (the concavo-convex structure has not been formed yet) A method of forming a concavo-convex structure on the surface of the unprocessed multilayer body on the resin composition B side; and (Method 2) A resin composition B in a liquid state is applied onto a substrate, and the applied resin composition Examples include a method in which a mold is applied to the layer of the product B, and the resin composition B is cured in that state to form an uneven structure layer.

  In Method 1, the raw multilayer body may be obtained by, for example, extrusion molding in which the resin composition A and the resin composition B are coextruded. An uneven structure can be formed by pressing a mold having a desired surface shape onto the surface of the unprocessed multilayer body on the resin composition B side.

  In Method 2, as the resin composition B constituting the concavo-convex structure layer, it is preferable to use a composition that can be cured by energy rays such as ultraviolet rays. The resin composition B is applied on a base material, and a UV light is emitted from a light source located on the back side of the application surface (on the opposite side of the base material to which the resin composition B is applied) in a state where the mold is applied. The resin composition B is cured by irradiating energy rays such as, and then the mold is peeled off, whereby the coating film of the resin composition B is used as an uneven structure layer to obtain a multilayer body.

(Relationship between light-emitting surface structure layer and reflective electrode layer structure)
In a preferred embodiment of the present invention, the reflective electrode layer has a structure having periodicity (for example, a lattice-like shape having periodicity or a row-like structure having periodicity), and the periodic pitch is the light emission. It is below the thickness of a surface structure layer. By having the said structure, the nonuniformity of the brightness | luminance in an apparatus light emission surface is reduced, and it can be set as the light source device which emits light uniformly. In other words, the organic EL light source device of the present invention may have uneven brightness due to the through-holes in the reflective electrode layer as compared with a device in which the reflective electrode layer is provided on the entire surface, but the periodic pitch is set to the predetermined pitch. And, more preferably, the diffusion element described above is provided so that the diffusion in the device is sufficiently compensated for the luminance unevenness due to the presence of the through-hole, and as a result, the device light exit surface. The luminance unevenness of the light emitted from is reduced.
This will be described with reference to the reflective electrode layer 112 (FIGS. 1 and 2) of the first embodiment. The reflective electrode layer 112 is configured by linear reflective electrode layers extending in the X-axis direction and the Y-axis direction. For example, when this is observed in a scanning manner from one end to the other end in the X-axis direction, a linear reflective electrode layer extending in the Y-axis direction and the through-hole 113 are formed. Observed periodically. Therefore, the distance A1 between the side of one through-hole and the corresponding side of the through-hole adjacent thereto is a periodic pitch. When the pitch A1 is equal to or less than the thickness of the light emitting surface structure layer 190, the light source device 100 can be a device that emits light uniformly.

  The periodic pitch can be observed in any direction parallel to the reflective surface of the reflective electrode layer. In the case where the linear structures of the reflective electrode layers are arranged in a lattice shape or a row shape, a periodic pitch can be observed in a direction orthogonal to the extending direction of the linear structure. When the linear structures are arranged in a grid, a plurality of periodic pitches can be observed. In that case, it is preferable that any one pitch satisfies the requirements of the preferred embodiment, and all pitches Is more preferable to satisfy the requirements of the preferred embodiments.

  The specific numerical range of the periodic pitch can be preferably 30 μm or more, more preferably 50 μm or more, while preferably 950 μm or less, more preferably 800 μm or less.

(Second Embodiment)
The first embodiment described above has a reflecting surface that is specularly reflected as the reflecting layer, and has a concavo-convex structure layer as the diffusing element, but the present invention is not limited to this. As in the embodiment, a layer that performs scattering reflection may be used as a reflection layer and a diffusing element.

FIG. 4 is an elevational sectional view schematically showing a layer configuration of an organic EL light source device according to the second embodiment of the present invention.
In FIG. 4, the light source device 200 does not have the concavo-convex structure layer 141, and is different in that the upper surface 101 U of the substrate 101 defines the device light-emitting surface and a scattering reflection layer 231 instead of the reflection layer 131. Unlike the first embodiment, other points are common.
Similar to the surface 131U of the reflective layer 131, the reflectance of the surface 231U of the scattering reflective layer 231 is higher than that of the upper surface 112U of the reflective electrode layer 112. However, the upper surface 231U of the scattering reflection layer 231 is a surface that exhibits white when visually observed, and is different from the surface 131U of the reflection layer 131 in that it reflects light in a scattered manner.

In the device 200 of the second embodiment, the light emitting layer 121 and the scattering reflection layer 231 are in contact with each other in the through hole 113 of the reflective electrode layer 112. Therefore, of the surface 231U of the scattering reflection layer 231 on the light emitting layer 121 side, the surface 231E in the region in the through hole 113 faces the light emitting layer 121, and the surface 231C in the other region is covered with the reflective electrode layer 112. ing.
Of the light generated in the light emitting layer 121, a part of the light traveling downward is reflected on the surface 112 </ b> U of the reflective electrode 112, and the other part is a part of the upper surface 231 </ b> U of the reflective layer 231. At 231E, the light is reflected with a higher reflectance. The light reflected on the surfaces 231E and 112U travels upward, and at least part of the light passes through the light emitting layer 121, the transparent electrode 111, and the substrate 101, and from the device light exit surface (in this example, the upper surface 101U of the substrate 101). Idemitsu.

  In the light source device 200 of the second embodiment, the scattering reflection layer 231 functions as a reflection layer and also functions as a diffusion element. By having such a scattering reflection layer as a diffusing element, the light extraction efficiency can be further increased. Specifically, at least of light emitted upward from the light emitting layer 121 (including light generated upward in the light emitting layer 121 and light reflected by the reflective electrode 112 and the reflective layer 231 and traveling upward). A part of the light is transmitted through the substrate 101 and emitted from the device light exit surface 101U, but the other part is not emitted but reflected by the device light exit surface 101U and returned to the inside of the device. In particular, at the interface between the substrate 101 and the outside of the apparatus, light whose angle formed by the interface and the light traveling direction is less than the critical angle is totally reflected and returned to the apparatus. Of the light returned into the apparatus by such reflection, the light that has reached the scattering reflection layer 231 is reflected in various directions due to the property that the scattering reflection layer 231 reflects the light and then travels upward again. . When this light reaches the interface between the substrate 101 and the outside of the apparatus again, the traveling direction of the light is diffused by the diffused reflection, so that it enters the interface at an angle greater than the critical angle and exits from the apparatus. The proportion of light increases. Here, in the organic EL light source device of the present invention, by combining the reflective layer having a high reflection efficiency and the reflective electrode, the effect of increasing the proportion of light emitted outside the device by the scattering reflective layer is further enhanced, Has a synergistic effect. Thus, the same effect as that of the concavo-convex structure layer that the first embodiment has as a diffusing element can be obtained also by the scattering reflection layer.

(Third embodiment)
The organic EL device of the present invention may have both the concavo-convex structure layer in the first embodiment described above and the scattering reflection layer in the second embodiment instead of either one as the diffusing element.
In the first embodiment and the second embodiment described above, the reflective electrode layer and the reflective layer are provided in direct contact with each other. However, the present invention is not limited to this, and for example, the third embodiment shown below. As in the embodiment, the reflective electrode layer and the reflective layer may be provided separately.

FIG. 5 is an elevational sectional view schematically showing a layer structure of an organic EL light source device according to the third embodiment of the present invention. In FIG. 5, the light source device 300 does not have the reflective layer 131 and differs from the first embodiment in that it has other components instead, and the other points are common.
The light source device 300 includes a sealing layer 351 provided in contact with the lower side of the light emitting layer 121 and the reflective electrode layer 112, and further includes a scattering reflection layer 331 via a gas layer 361 on the lower side thereof. The gas layer 361 is defined by supporting the sealing layer 351 and the scattering reflection layer 331 with the support 362. A dehumidifying agent 363 is provided in the gas layer 361 to reduce elements in the gas layer 361 that degrade light emitting elements such as moisture. A light-emitting element including the transparent electrode layer 111, the light-emitting layer 121, and the reflective electrode layer 112 includes a substrate 101, a sealing member (not shown) provided on the side of the device as necessary, a sealing layer 351, a gas layer 361, and scattering reflection. The layer 331 and other components provided as necessary can protect the elements from the outside of the device from deterioration.

  Similar to the surface 131U of the reflective layer 131 of the first embodiment, the reflectance of the surface 331U of the scattering reflective layer 331 is higher than the upper surface 112U of the reflective electrode layer 112. However, the upper surface 331U of the scattering reflection layer 331 is a surface exhibiting white when visually observed, similarly to the upper surface 231U of the scattering reflection layer 231 of the second embodiment, and scatters light. reflect.

  In the device 300 of the third embodiment, the light emitting layer 121 and the sealing layer 351 are in contact with each other in the through hole 113 of the reflective electrode layer 112. Of the light generated in the light emitting layer 121, a part of the light traveling downward is reflected on the surface 112 U of the reflective electrode 112, and the other part passes through the through hole 113 and passes through the sealing layer 351. Then, it reaches the interface between the sealing layer 351 and the gas layer 361. Most of the light reaching here is reflected at this interface, but the remaining part is transmitted through the gas layer 361 and reaches the upper surface 331U of the scattering reflection layer 331, which is higher than the surface of the reflection electrode layer. Reflected with reflectivity. Therefore, also in such a form, the effect by the combination of a reflective electrode layer and a reflective layer can be acquired. Furthermore, in the apparatus 300 of the third embodiment, the diffusion effect by both the uneven structure layer 141 and the scattering reflection layer 331 can be obtained, synergistically with the effect by the combination of the reflective electrode layer and the reflective layer, High light extraction efficiency can be realized.

  In the third embodiment, the reflective electrode layer 112 and the scattering reflective layer 331 which is a reflective layer are separated from each other. Therefore, part of the light reflected by the scattering reflection layer 331 reaches the surface 112L of the reflective electrode layer 112 on the side opposite to the light emitting layer. In the light source device of the present invention, the reflectance of the surface of the reflective electrode layer on the side opposite to the light emitting layer is not particularly limited, but can usually be a reflectance equivalent to the reflectance of the surface on the light emitting layer side.

  In the third embodiment, as a material of the sealing layer 351, a substance that can transmit light and has sealing performance can be appropriately selected. Specifically, for example, a material similar to that of the substrate 101 can be used. The gas in the gas layer 361 can be normal air, or an inert gas such as argon or nitrogen, which can further reduce deterioration of the light emitting element.

(Modification)
The organic EL light source device of the present invention is not limited to the above embodiment, and various modifications can be made to the above embodiment.

(Modification: Arbitrary layer)
In the third embodiment described above, the scattering reflection layer 331 is provided via the gas layer 361 as a layer below the sealing layer 351. However, in the organic EL light source device of the present invention, another layer is provided. May be provided. For example, a substrate such as glass can be provided below the gas layer 361, and a scattering reflection layer can be provided further below.

(Modification: Reflective electrode layer structure)
In the embodiment described above, the reflective electrode layer has the lattice-like structure shown in FIG. 2, but the organic EL light source device of the present invention has another form as the reflective electrode layer. Also good. For example, as shown in the reflective electrode layer 612 in FIG. 6, linear structures 614 extending in the Y-axis direction are aligned in parallel in the X-axis direction, and band-shaped through holes 613 are formed between the linear structures 614. It can also have a row-like structure. In this case, the periodic pitch of the reflective electrode layer 612 can be a periodic pitch observed in the direction orthogonal to the linear structure 614, that is, in the X-axis direction, specifically in the X-axis direction. The distance A2 between the side of one through hole and the corresponding side of the through hole adjacent thereto can be set.

  In addition, the reflective electrode layer may have a shape in which through holes having an arbitrary shape such as a round shape are aligned on a plane.

(Modification: Transparent electrode structure)
In the embodiment described above, the transparent electrode layer 111 is a flat layer that extends over the entire region of the light output surface of the device. In the organic EL light source device of the present invention, the transparent electrode layer is, for example, a reflective electrode. Similar to the layer, it may have a through-hole.
However, in the organic EL light source device of the present invention, the transparent electrode layer is preferably a flat layer as shown in the first to third embodiments. When the transparent electrode layer is a flat layer, the in-plane voltage can be made uniform even when the resistance of the transparent electrode layer is high. For example, it is possible to reduce the tendency that the voltage near the center of the light exit surface of the apparatus decreases and the vicinity of the center becomes dark. Further, if the transparent electrode layer has a through-hole or a concavo-convex structure, the luminescent layer also has a concavo-convex structure following that, and the concavo-convex structure portion of the luminescent layer may be a starting point for deterioration, while the transparent electrode When the layer is a flat layer, the starting point of such deterioration can be reduced.

(Modification: Light-emitting surface structure layer, uneven structure layer)
In the first and third embodiments described above, as the concavo-convex structure of the concavo-convex structure layer 141, a rectangular pyramid-shaped concave portion 142 is aligned in the X-axis direction and the Y-axis direction and arranged at intervals. Although shown, the concavo-convex structure in the present invention is not limited to this, and may have various shapes. For example, instead of the quadrangular pyramid-like structural unit, a prism other than the quadrangular pyramid, a pyramid, a part of the pyramid and a trapezoidal cross-sectional shape, a cone, a sphere, or a part of an elliptic rotating body can be used. Further, the concavo-convex structure may be a row-like shape in which a large number of groove-like concave portions and / or convex portions that are continuous from one side of the device light-emitting surface to the other opposing sides are arranged in parallel. The height of such a concavo-convex structure is not particularly limited, but is preferably 0.3 to 100 μm as the difference between the highest part and the lowest part.
Further, when the concavo-convex structure has a concave portion and a flat portion like the concavo-convex structure of the concavo-convex structure layer 141, the ratio of the region occupied by the concave portion and the region occupied by the flat portion when observed from above the device is 19: 1. ˜4: 6 is preferable, and 9: 1 to 5: 5 is more preferable.

  Further, the concavo-convex structure of the concavo-convex structure 141 has a concave portion having the same shape and a flat portion having the same height on the entire surface of the device light exit surface. However, the concavo-convex structure in the present invention is not limited to this, Concave portions and / or convex portions may be mixed, and a plurality of levels of flat portions having different heights may be mixed. By using such a random shape, it is possible to prevent rainbow unevenness on the light exit surface of the apparatus. In addition, by reducing the interference of light inside the device and combining it with an increase in the amount of reflection due to the reflective layer or the like, it is possible to obtain effects such as further improvement in light extraction efficiency.

  In the first and third embodiments described above, the concave-convex structure layer 141 is a component different from the substrate 101 in the light-emitting surface structure layer 190. However, in the present invention, the mode of the light-emitting surface structure layer is this. However, the light-emitting surface structure layer may be formed integrally with a common member. Conversely, the light exit surface structure layer may further include an arbitrary layer in addition to the substrate and the uneven structure layer.

  Furthermore, in the organic EL light source device of the present invention, the diffusing element is not limited to the concavo-convex structure layer and the scattering reflection layer, and may take any configuration that diffuses light in the device instead of or in addition to these. it can. For example, a flat diffusing element having a diffusing agent can be provided at any position between the device light exit surface and the reflective layer.

(Other components)
The organic EL light source device of the present invention can include arbitrary components for configuring the light source device in addition to the components described above. For example, a wiring for energizing the light emitting element, a sealing member for sealing the light emitting element, an adhesive layer for bonding between layers, and a peripheral part of the light emitting surface of the device to ensure physical strength or as a housing Any component such as a functioning member may be included.

(Use)
Although the use of the organic EL light source device of the present invention is not particularly limited, it can be used as a light source such as a backlight of a liquid crystal display device or a lighting device by taking advantage of high light extraction efficiency.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

<Example 1>
The light extraction efficiency of the organic EL light source device 100 having the configuration of the first embodiment of the present invention shown in FIG. 1 was simulated based on the following setting conditions.

In the organic EL light source device 100 shown in FIG. 1, the concavo-convex structure on the top surface of the concavo-convex structure layer 141 is adjacent to the angle of 60 ° formed by the slope of the regular quadrangular pyramid-shaped concave portion and the light-emitting surface of the device, The distance between the quadrangular pyramid recesses was 8 μm, and as a result, the periodic pitch was 40 μm.
The reflectivity of the reflective electrode layer 112 was 85% assuming aluminum. The reflection mode was specular reflection.
The reflectance of the reflective layer 131 was 98%, and the reflection mode was specular reflection.
The area ratio between the reflective surface 112U of the reflective electrode layer 112 and the reflective surface 131E of the reflective layer 131 was set to 36:64.
The refractive indexes of the concavo-convex structure layer 141, the substrate 101, the transparent electrode layer 111, and the light emitting layer 121 were 1.53, 1.53, 1.9, and 1.8, respectively.
The thicknesses of the uneven structure layer 141, the substrate 101, the transparent electrode layer 111, and the light emitting layer 121 were 15 μm, 500 μm, 0.2 μm, and 100 nm, respectively. The light distribution characteristic of the light source from the light emitting layer was Lambertian.

  For comparison, the organic EL light source device shown in FIG. 7 was assumed. The light source device 700 shown in FIG. 7 does not have the reflective layer 131, and instead of the reflective electrode 112, the reflective electrode layer 712 provided in the entire region of the reflective surface of the device is provided. It was set as having the same configuration.

  Based on the above setting conditions, the light extraction efficiency was simulated by a program (program name: Light Tools, manufactured by Optical Research Associates), and the light extraction efficiency of the light source device 100 and the light source device 700 was compared. As a result, the light extraction efficiency of the light source device 100 was 1.06 times that of the light source device 700.

<Example 2>
The light extraction efficiency of the organic EL light source device 200 having the configuration of the second embodiment of the present invention shown in FIG. 4 was simulated based on the following setting conditions.

In the organic EL light source device 200 shown in FIG. 4, the reflectance of the reflective electrode layer 112 is 85% assuming aluminum. The reflection mode was specular reflection.
The reflectance of the reflective layer 231 was 98%, and the reflection mode was white scattering.
The area ratio of the reflective surface 112U of the reflective electrode layer 112 to the reflective surface 131E of the reflective layer 231 was 36:64.
The settings for the substrate 101, the transparent electrode layer 111, and the light emitting layer 121 were the same as in Example 1.

  For comparison, the organic EL light source device shown in FIG. 8 was assumed. The light source device 800 shown in FIG. 8 does not have the reflective layer 231 and is replaced with the light source device 200 except that a reflective electrode layer 712 provided in the entire region of the device reflective surface is provided instead of the reflective electrode 112. It was set as having the same configuration.

  Based on the above setting conditions, the light extraction efficiency was simulated by the same program as in Example 1, and the light extraction efficiency of the light source device 200 and the light source device 800 was compared. As a result, the light extraction efficiency of the light source device 200 was 1.85 times that of the light source device 800.

<Example 3>
Except that the reflectance of the reflective layer 131 is 98% and the reflection mode is white scattering, the light extraction efficiency is simulated under the same setting conditions as in Example 1, and the light extraction efficiency of the light source device 100 and the light source device 700 is calculated. Contrasted. As a result, the light extraction efficiency of the light source device 100 was 1.11 times that of the light source device 700.

<Example 4>
The light extraction efficiency of the organic EL light source device 300 having the configuration of the third embodiment of the present invention shown in FIG. 5 was simulated based on the following setting conditions.

The refractive indexes of the sealing layer 351 and the gas layer 361 were 1.53 and 1.0, respectively.
The thicknesses of the sealing layer 351 and the gas layer 361 were both 1 μm.
The reflectance of the reflective layer 331 was 98%, and the reflection mode was white scattering.
The area ratio between the reflective surface 112U of the reflective electrode layer 112 and the through hole 113 of the reflective layer 231 was 36:64.
The settings for the concavo-convex structure layer 141, the substrate 101, the transparent electrode layer 111, and the light emitting layer 121 were the same as those in Example 1.

  Based on the above setting conditions, the light extraction efficiency was simulated by the same program as in the first embodiment, and the light extraction efficiency of the light source device 300 and the light source device 700 simulated in the first embodiment was compared. As a result, the light extraction efficiency of the light source device 100 was 1.29 times that of the light source device 700.

Claims (4)

An organic electroluminescence light source device having a transparent electrode layer, a light emitting layer, a reflective electrode layer, and a reflective layer in this order from the light exit surface side,
The reflective electrode layer has a through hole,
The reflectance of the reflective layer is, the reflective electrode layer, rather larger than the reflectivity of the surface of the light-emitting layer side,
The organic electroluminescence light source device has a diffusing element that diffuses light as the reflective layer or the additional layer,
The organic electroluminescence light source device has the reflection layer, which is a white scattering reflection layer, as the diffusing element . 2. The organic electroluminescence light source device according to claim 1 , wherein the diffusion element has a light diffusion layer or a concavo-convex structure layer provided on a light exit surface side of the transparent electrode layer. 3. The organic electroluminescence light source device according to claim 1 , further comprising a gas layer between the reflective layer and the reflective electrode layer. It is an organic electroluminescent light source device of any one of Claims 1-3 ,
A light-emitting surface structure layer that is provided in contact with the surface of the transparent electrode layer opposite to the light-emitting layer and that defines a light-emitting surface of the device;
The reflective electrode layer has a periodic or grid shape having periodicity,
The organic electroluminescence light source device wherein the periodic pitch is equal to or less than the thickness of the light-emitting surface structure layer.

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