JP2017097948A - Organic electroluminescence element and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic electroluminescence element in which the contour of a light source is difficult to be viewed from the outside while suppressing reduction of a light extraction efficiency.SOLUTION: An organic EL element 1 has a planar shape, and includes a first electrode 2 having light transmittance, a second electrode 3 paired with the first electrode 1, an organic light emitting layer 4 disposed between the first electrode 2 and the second electrode 3, and a diffusion structure. The diffusion structure more greatly diffuses light which passes from the organic light emitting layer 4 through the vicinity of the outer peripheral edge of the first electrode 2 and is emitted to the outside, as compared with light which passes from the organic light emitting layer 4 through the central portion of the first electrode 2 and is emitted to the outside.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic electroluminescence element and a lighting fixture using the same.

  As an organic electroluminescence element (hereinafter referred to as “organic EL element”), a substrate is known in which a light transmissive electrode, an organic light emitting layer composed of a plurality of layers, and a pair of electrodes are laminated. Yes. And in order to improve the light extraction efficiency from an organic EL element, providing various light extraction structures in an organic EL element is proposed. As an example of this, a low refractive index layer having a refractive index lower than that of the substrate, a high refractive index layer having a refractive index higher than that of the low refractive index layer, and a transparent electrode are laminated in this order on the surface of the transparent substrate. There is a technique for roughening the surface of the refractive index layer on the high refractive index layer side (see, for example, Patent Document 1). In this technology, the low refractive index layer and the high refractive index layer constitute a light extraction structure, and light diffuses at the interface between the low refractive index layer and the high refractive index layer, that is, the traveling direction of the light changes. Thus, the amount of light transmitted through the substrate is increased, and as a result, the light extraction efficiency is improved.

JP 2005-274741 A

  The light extraction structure improves the light extraction efficiency by diffusing the light emitted from the organic EL element. However, when the degree of light diffusion increases, the light extraction efficiency decreases. For this reason, the light extraction structure is configured not to diffuse light excessively.

  However, if the diffusibility of the light emitted from the organic EL element is low, a bright light source and a non-light-emitting area outside the organic EL element are clearly visible from the outside when the organic EL element emits light. In particular, when an organic EL element is applied to a lighting fixture, the outline of the light source is easily visually recognized from the outside, or when a plurality of organic EL elements are arranged side by side, the joint between the light sources becomes conspicuous.

  In other words, if priority is given to improving the light extraction efficiency, the outline of the light source is easily seen from the outside, and if the outline of the light source is not easily seen from the outside, the light extraction efficiency is lowered. Occur.

  This invention is made | formed in view of the said problem, and it aims at providing the organic EL element and lighting fixture which make it difficult to visually recognize the outline of a light source from the outside, suppressing the fall of light extraction efficiency.

The organic EL device according to the first aspect of the present invention is:
A first electrode having a planar shape and having optical transparency;
A second electrode paired with the first electrode;
An organic light emitting layer disposed between the first electrode and the second electrode;
The light emitted from the organic light emitting layer through the vicinity of the outer peripheral edge of the first electrode to the outside is diffused more than the light emitted from the organic light emitting layer through the central portion of the first electrode to the outside. A diffusion structure composed of
Is provided.

The organic EL device according to the second aspect of the present invention, in the first aspect,
A diffusion layer disposed at a position opposite to the organic light emitting layer with respect to the first electrode,
The diffusion layer defines the diffusion structure;
The diffusion layer is configured to transmit and diffuse the light passing through the first electrode, and the light diffusibility of the diffusion layer increases from the central portion of the diffusion layer toward the outer peripheral edge.

The organic EL device according to the third aspect of the present invention is the second aspect,
The diffusion layer includes a diffusion surface facing the first electrode or facing the opposite side of the first electrode,
The diffusion surface comprises a plurality of recesses or a plurality of protrusions,
The depth of the recess or the height of the protrusion increases from the center of the diffusion layer toward the outer periphery.

The organic EL device according to the fourth aspect of the present invention, in the third aspect,
A high refractive index layer disposed between the diffusion layer and the first electrode and having a higher refractive index than the diffusion layer;
The diffusion surface is opposed to the first electrode;
The high refractive index layer is in contact with the diffusion surface of the diffusion layer.

The organic EL device according to the fifth aspect of the present invention is any one of the second to fourth aspects.
The diffusion layer contains diffusion particles,
The density of the diffusion particles increases from the center of the diffusion layer toward the outer periphery.

The organic EL device according to the sixth aspect of the present invention is any one of the second to fifth aspects.
The diffusion layer is divided in a direction orthogonal to an axis along a direction in which the first electrode, the organic light emitting layer, and the second electrode are arranged.

  A lighting fixture according to a seventh aspect of the present invention includes the organic EL element according to any one of the first to sixth aspects, and a fixture body that holds the organic EL element.

  According to the present invention, the degree of diffusion of light that passes through the vicinity of the outer peripheral edge of the first electrode and exits to the outside increases. For this reason, when an organic EL element is observed from the outside, it becomes difficult to visually recognize the outline of the organic light emitting layer as a light source. On the other hand, since the degree of diffusion of the light that passes through the central portion of the first electrode and is emitted to the outside is smaller than that in the vicinity of the outer peripheral edge, a decrease in light extraction efficiency is suppressed. For this reason, the fall of the light extraction efficiency which is easy to occur with the improvement of light diffusibility is suppressed.

FIG. 1A is a sectional view showing an organic EL element according to the first embodiment of the present invention, and FIG. 1B is a partial sectional view showing a diffusion layer in the organic EL element. It is a top view which shows the diffusion layer in the organic EL element which concerns on 1st embodiment of this invention. It is a partial sectional view showing a modification of the diffusion layer in the organic EL device according to the first embodiment of the present invention. 4A is a cross-sectional view showing a first modification of the organic EL element according to the first embodiment of the present invention, and FIG. 4B is a partial cross-section showing a diffusion layer in the organic EL element. FIG. FIG. 5A is a cross-sectional view showing a second modification of the organic EL element according to the first embodiment of the present invention, and FIG. 5B is a partial cross-section showing a diffusion layer in the organic EL element. FIG. FIG. 6A is a cross-sectional view showing a third modification of the organic EL element according to the first embodiment of the present invention, and FIG. 6B is a partial cross-section showing a diffusion layer in the organic EL element. FIG. FIG. 7A is a cross-sectional view showing an organic EL element according to the second embodiment of the present invention, and FIG. 7B is a partial cross-sectional view showing a diffusion layer in the organic EL element. It is a schematic plan view which shows the diffusion layer in the organic EL element which concerns on 2nd embodiment of this invention. FIG. 9A is a cross-sectional view showing an organic EL element according to the third embodiment of the present invention, and FIG. 9B is a partial cross-sectional view showing a diffusion layer in the organic EL element. It is sectional drawing which shows an example of the lighting fixture which concerns on this invention.

  FIG. 1A and FIG. 1B show an organic EL element 1 according to the first embodiment of the present invention. FIG. 2 shows the axis of the diffusion layer 6 in the organic EL element in FIG. The top view seen in the direction along X is shown.

  The organic EL element 1 according to the first embodiment has a planar shape, a light-transmitting first electrode 2, a second electrode 3 paired with the first electrode 2, a first electrode 2, and a first electrode And an organic light emitting layer 4 disposed between the two electrodes 3. The organic EL element 1 further includes a diffusion structure. The diffusion structure is such that light emitted from the organic light emitting layer 4 through the vicinity of the outer peripheral edge of the first electrode 2 to the outside is emitted from light emitted from the organic light emitting layer 4 through the central portion of the first electrode 2 to the outside. Is also configured to diffuse.

  The central part of the first electrode 2 is a part inside the outer peripheral edge of the first electrode 2, and the light passing through this part is not diffused by the diffusion structure or passes through the vicinity of the outer peripheral edge of the first electrode 2. It is designed to diffuse more weakly than the light it does. The central portion of the first electrode 2 is preferably a central point of the first electrode 2 or a portion consisting of the central point and its vicinity.

  The organic EL element 1 according to the first embodiment includes a diffusion layer 6 disposed at a position opposite to the organic light emitting layer 4 with respect to the first electrode 2. The diffusion layer 6 defines the diffusion structure. The diffusion layer 6 is configured to transmit and diffuse light passing through the first electrode 2. The light diffusibility of the diffusion layer 6 increases from the center of the diffusion layer 6 toward the outer periphery.

  The central portion of the diffusion layer 6 is a portion inside the outer peripheral edge of the diffusion layer 6 and is a portion having the smallest light diffusibility in the diffusion layer 6. The central portion of the diffusion layer 6 is preferably located at a position overlapping the central portion of the first electrode 2 in the direction along the axis X. The central portion of the diffusion layer 6 is preferably a central point of the diffusion layer 6 or a portion consisting of the central point and its vicinity.

  In the first embodiment, since the light diffusibility of the diffusion layer 6 is enhanced in the vicinity of the outer peripheral edge, when the organic EL element 1 is observed from the outside, the outline of the organic light emitting layer 4 that is a light source is visually recognized. It becomes difficult to distinguish between a light source and a dark part around it. On the other hand, since the light diffusibility of the center part of the diffusion layer 6 is smaller than the vicinity of the outer peripheral edge, a decrease in light extraction efficiency is suppressed at the center part of the diffusion layer 6. For this reason, the fall of the light extraction efficiency which is easy to occur with the improvement of light diffusibility is suppressed.

  In the diffusion layer 6, the light diffusibility may increase continuously from the central portion of the diffusion layer 6 toward the outer peripheral edge, or may increase stepwise.

  The degree of light diffusibility at a specific position of the diffusion layer 6 is evaluated to be higher as the integrated intensity of 10 ° to 90 ° reflected light from the specific position of the diffusion layer 6 is higher. Specifically, it is evaluated as follows. A light parallel to the axis X is irradiated from the outside of the organic EL element 1 to a specific position of the diffusion layer 6 in the organic EL element 1. The axis X is along the direction in which the first electrode 2, the organic light emitting layer 4 and the second electrode 3 are arranged. The axis X usually coincides with the normal line of the surface of the first electrode 2 facing the organic light emitting layer 4. The wavelength of the light irradiated to the specific position should just be a wavelength contained in the wavelength range of the light which the organic light emitting layer 4 emits. Incident light is unpolarized. In this case, the integrated intensity of the reflected light from the specific position of the diffusion layer 6 toward the direction inclined by 10 ° to 90 ° from the axis X is measured. The integrated intensity of the reflected light is an index of the degree of light diffusibility at a specific position of the diffusion layer 6, and it is evaluated that the higher the intensity of the reflected light, the higher the light diffusibility at the specific position.

  The diffusion layer 6 preferably includes a diffusion surface 7 that faces the first electrode 2 or faces away from the first electrode 2. In the first embodiment, the diffusion layer 6 includes a diffusion surface 7 that faces the first electrode 2. The diffusion surface 7 includes a plurality of inclined surfaces 71. The inclined surface 71 is inclined with respect to the axis X along the direction in which the first electrode 2, the organic light emitting layer 4 and the second electrode 3 are arranged. The inclination angle of the inclined surface 71 with respect to the axis X increases from the central portion of the diffusion layer 6 toward the outer peripheral edge.

  For this reason, the diffusion layer 6 is given a property that its light diffusibility increases from the center of the diffusion layer 6 toward the outer periphery. That is, as the inclination angle of the inclined surface 71 increases, the light passing through the inclined surface 71 is more easily diffused. Therefore, when the inclination angle increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, Light diffusibility increases from the center of the diffusion layer 6 toward the outer periphery.

  The diffusion surface 7 includes a plurality of recesses 72 or a plurality of protrusions 73 (see FIG. 3). The depth dimension of the recesses 72 or the height dimension of the protrusions 73 extends from the central portion of the diffusion layer 6 toward the outer peripheral edge. May be larger. In the first embodiment, the diffusion surface 7 includes a plurality of recesses 72, and the depth dimension of the recesses 72 increases from the central portion of the diffusion layer 6 toward the outer peripheral edge.

  Even in this case, the diffusion layer 6 is given the property that its light diffusibility increases from the center of the diffusion layer 6 toward the outer periphery. That is, as the depth dimension of the recess 72 is larger, light passing through the recess 72 is more easily diffused. Therefore, when the depth dimension increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, the diffusion layer 6 becomes higher from the center of the diffusion layer 6 toward the outer periphery.

  As shown in FIG. 3, the diffusion surface 7 may include a protrusion 73. In the case where the diffusing surface 7 includes the protrusion 73, the light passing through the protrusion 73 is more easily diffused as the height dimension of the protrusion 73 is larger. For this reason, when the height dimension increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, the light diffusibility of the diffusion layer 6 increases from the central portion of the diffusion layer 6 toward the outer peripheral edge.

  As in the case where the diffusing surface 7 is a rough surface, when it is difficult to determine whether the diffusing surface 7 has a plurality of recesses 72 or a plurality of protrusions 73, the diffusing surface 7 has a plurality of recesses 72. It may be considered that the diffusion surface 7 includes a plurality of protrusions 73.

  The side surface of the recess 72 or the side surface of the protrusion 73 in the diffusing surface 7 preferably defines the inclined surface 71. In the first embodiment, the side surface of the recess 72 defines the inclined surface 71 as shown in FIG. 1B, but the side surface of the protrusion 73 may define the inclined surface 71 as shown in FIG. In this case, the recesses 72 or protrusions 73 and the inclined surface 71 which are elements that govern the light diffusibility are arranged on the diffusion surface 7 with high density.

  In the first embodiment, the organic EL element 1 includes a high refractive index layer 9 interposed between the diffusion layer 6 and the first electrode layer 2. The high refractive index layer 9 has a higher refractive index than the diffusion layer 6. As described above, in the first embodiment, the diffusion surface 7 faces the first electrode layer 2, and the high refractive index layer 9 is in contact with the diffusion surface 7.

  Although the diffusing surface 7 is uneven because the recess 72 and the inclined surface 71 are formed, in the first embodiment, the diffusing surface 7 is covered and concealed by the high refractive index layer 9. For this reason, when the diffusion layer 6 is incorporated in the organic EL element 1, the shape of the diffusion surface 7 is less likely to affect the structure of the organic EL element 1. Furthermore, when the light emitted from the organic light emitting layer 4 is incident on the diffusion layer 6 from the high refractive index layer 9, reflection at the interface between the high refractive index layer 9 and the diffusion layer 6 is suppressed, and this light is Diffused. For this reason, the light extraction efficiency of the organic EL element 1 is increased.

  In 1st embodiment, it is preferable that the diffusion layer 6 contains a diffusion particle. It is preferable that the density of the diffusion particles in the diffusion layer 6 increases from the center of the diffusion layer 6 toward the outer peripheral edge.

  This also gives the diffusion layer 6 the property that its light diffusibility increases from the center of the diffusion layer 6 toward the outer periphery. The reason is as follows. The diffusion particles are particles made of a material different from the parent phase of the diffusion layer 6. The diffusing particles improve the light diffusibility by generating an interface between different phases in the diffusion layer 6. The higher the density of the diffusing particles, the easier it is for light to diffuse. For this reason, when the density of the diffusion particles increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, the light diffusibility of the diffusion layer 6 increases from the central portion of the diffusion layer 6 toward the outer peripheral edge.

  The density of the diffusing particles is evaluated by the size of the area of the interface between the different phases in the diffusing layer 6 generated by the diffusing particles. When the area of the interface between the different phases per unit volume of the diffusion layer 6 is larger, it is evaluated that the density of the diffusion particles is higher. When there is no variation in the particle size of the diffusion particles in the diffusion layer 6, the number of diffusion particles per unit volume of the diffusion layer 6 serves as an index of the density of the diffusion particles, and the number of diffusion particles per unit volume of the diffusion layer 6. It is evaluated that the density of the diffusing particles is higher as there is more.

  The diffusion layer 6 may be divided in a direction orthogonal to the axis X. As described above, the axis X is along the direction in which the first electrode 2, the organic light emitting layer 4, and the second electrode 3 are arranged.

  In this case, the diffusion layer 6 is hardly cracked, and the reliability of the organic EL element 1 is increased. The configuration in which the diffusion layer 6 is divided will be described in detail in the second embodiment.

  The organic EL element 1 according to the first embodiment can constitute a lighting fixture. For example, a lighting fixture including the organic EL element 1 according to the first embodiment and a fixture main body that holds the organic EL element 1 is obtained.

  The configuration of the organic EL element 1 according to the first embodiment will be described in more detail.

  The organic EL element 1 includes a first base material 11, an element body 5, a second base material 12, and a light extraction layer 10. The element body 5 includes a first electrode 2, a second electrode 3, and an organic light emitting layer 4. The light extraction layer 10 includes a diffusion layer 6 and a high refractive index layer 9.

  The first electrode 2 in the element body 5 is configured to function as an anode, and the second electrode 3 is configured to function as a cathode. The first electrode 2 may be configured to function as a cathode, and the second electrode 3 may be configured to function as an anode.

  The first electrode 2 has light transparency. In this specification, the light transmitting property is a property of a substance that transmits light, and includes light transmitting property and transparency. The first electrode 2 is formed from a material having both conductivity and light transmission, for example. Examples of this material include conductive transparent metal oxides such as ITO, IZO, and AZO; conductive polymers such as PEDOT and polyaniline; conductive polymers doped with any acceptor; and carbon nanotubes. . The first electrode 2 is formed into a thin film by a method such as vacuum deposition, sputtering, or coating. In vacuum deposition and sputtering, the first electrode 2 can be produced at low cost by patterning the first electrode 2 using a mask.

  The organic light emitting layer 4 is a layer containing an organic compound that is a light emitting substance. The thickness of the organic light emitting layer 4 is in the range of 60 to 1000 nm, for example. The structure of the organic light emitting layer 4 in an organic electroluminescent element is well-known. The organic light emitting layer 4 includes, for example, a light emitting layer containing an organic compound, or further includes one or more layers selected from the group consisting of a hole injection layer, a hole transport layer, an electron transport layer, an electron injection layer, and an intermediate layer. Prepare. When the first electrode 2 is an anode and the second electrode 3 is a cathode, the organic light-emitting layer 4 is formed of, for example, a hole transport layer, a light-emitting layer, an electron transport layer, and the like from the first electrode 2 toward the second electrode 3. It has a structure in which electron injection layers are sequentially stacked. The organic light emitting layer 4 may have a so-called multi-unit structure.

The second electrode 3 preferably has light reflectivity. In this case, the light extraction efficiency of the organic EL element 1 is increased. When light is extracted from the organic EL element 1 to the outside through the second electrode 3, the second electrode 3 may have light transmittance. The 2nd electrode 3 is produced from the material which consists of a metal, an alloy, an electrically conductive compound, or these mixtures, for example. More specifically, the second electrode 3 includes, for example, a metal such as aluminum, silver, and magnesium; an alloy such as a magnesium-silver mixture, a magnesium-indium mixture, and an aluminum-lithium alloy; a metal oxide such as Al ₂ O ₃ ; And made from a material selected from the group consisting of mixtures such as Al / Al ₂ O ₃ .

  The first electrode 2 of the element body 5 faces the first base material 11. The first base material 11 supports the element body 5. “The first base material 11 supports the element body 5” means not only the case where the element body 5 directly overlaps the first base material 11, but also the element body 5 and the first base material. 11 includes a case where an appropriate layer is interposed. In the first embodiment, the light extraction layer 10 is interposed between the element body 5 and the first base material 11.

  The first base material 11 has light transmittance. The first substrate 11 may be colorless and transparent, or may be slightly colored. The first substrate 11 may be translucent. The first substrate 11 may be ground glass. The first substrate 11 may be, for example, a transparent glass plate formed from soda lime glass, non-alkali glass, or the like, a plastic film formed from a polyester resin, a polyolefin resin, a polyamide resin, an epoxy resin, a fluorine resin, or the like. A plastic plate may be used.

  The first base material 11 may be provided with light diffusibility by containing particles, powder, bubbles, or the like having a refractive index different from that of the matrix of the first base material 11. . The surface of the first substrate 11 may have a shape for imparting light diffusibility to the first substrate 11. In order to reduce the temperature rise due to heat generation of the element body 5, the first base material 11 may have high thermal conductivity. When the 1st base material 11 has moisture permeability, in order to suppress the penetration | invasion of the water | moisture content in the organic EL element 1, it is also preferable to laminate | stack the layer which has moisture resistance on the 1st base material 11. FIG.

  The light extraction layer 10 is configured to increase the amount of light extracted when the light emitted from the organic light emitting layer 4 is extracted to the outside of the organic EL element 1. The surface of the light extraction layer 10 that faces the first electrode 2 is in contact with the first electrode 2, and the surface that faces the first substrate 11 is in contact with the first substrate 11.

  The high refractive index layer 9 in the light extraction layer 10 is overlaid on the surface of the diffusion layer 6 facing the first electrode 2. The surface of the high refractive index layer 9 facing the first electrode 2 is in contact with the first electrode 2, and the surface of the diffusion layer 6 facing the first substrate 11 is in contact with the first substrate 11.

  The high refractive index layer 9 has a higher refractive index than the diffusion layer 6. The refractive index difference between the diffusion layer 6 and the high refractive index layer 9 is, for example, 0.1 or more, 0.5 or more, 1 or more, or 2 or more. The refractive index of the diffusion layer 6 is in the range of 1.4 to 1.7, for example. The refractive index of the high refractive index layer 9 is in the range of 1.6 to 2.0, for example. In order to prevent cracks in the light extraction layer 10, it is preferable that the difference in linear expansion coefficient between the diffusion layer 6 and the high refractive index layer 9 is small. The refractive index of the high refractive index layer 9 is preferably approximate to the refractive index of the first electrode 2. In this case, total reflection of light at the interface between the high refractive index layer 9 and the first electrode 2 is suppressed, and the light extraction efficiency is further improved. The difference in refractive index between the high refractive index layer 9 and the first electrode 2 is preferably 0.2 or less, and more preferably 0.1 or less.

The high refractive index layer 9 is made of, for example, a resin. The high refractive index layer 9 preferably contains nanoparticles having a high refractive index, such as TiO ₂ particles, for adjusting the refractive index. The high refractive index layer 9 is produced by molding a molding material containing, for example, an organic resin. Examples of the organic resin include acrylic resins and epoxy resins. The molding material preferably contains nanoparticles having a high refractive index. The molding material may contain one or more additives selected from a curing agent, a curing accelerator, and a curing initiator, if necessary. The high refractive index layer 9 may be made of an inorganic material such as SiN or SiO ₂ .

  In the first embodiment, the diffusion surface 7 of the diffusion layer 6 faces the first electrode 2. For this reason, the high refractive index layer 9 is in contact with the diffusion surface 7.

  The diffusion surface 7 shown in FIGS. 1 (a) and 1 (b) includes a plurality of recesses 72, and the side surface of the recess 72 defines an inclined surface 71. As shown in FIG. A plurality of protrusions 73 may be provided, and a side surface of the protrusion 73 may define the inclined surface 71. As described above, when it is difficult to determine whether the diffusing surface 7 includes a plurality of recesses 72 or a plurality of protrusions 73, as in the case where the diffusing surface 7 is entirely rough, the diffusing surface 7 may be regarded as including a plurality of recesses 72, and the diffusion surface 7 may be regarded as including a plurality of protrusions 73.

  The diffusion surface 7 may have a lens array structure by including a plurality of protrusions 73. In that case, the shape of the protrusion 73 on the diffusing surface 7 may be hemispherical, bowl-shaped or cone-shaped. The diffusion surface 7 may have a diffractive structure.

  The diffusion layer 6 is composed of, for example, a plurality of portions having different light diffusivities. These portions are arranged so that the light diffusibility of the diffusion layer 6 increases from the central portion toward the outer peripheral edge. In the first embodiment, as illustrated in FIG. 2, the diffusion layer 6 includes a low diffusion portion 61 and a high diffusion portion 62 having higher light diffusibility than the low diffusion portion 61. In the low diffusion part 61, there is a central part of the diffusion layer 6. For example, the center point of the low diffusion part 61 or the center point and the vicinity thereof coincide with the center part of the diffusion layer 6. The high diffusion part 62 surrounds the low diffusion part 61 along the outer peripheral edge of the low diffusion part 61. The outer peripheral edge of the high diffusion portion 62 defines the outer peripheral edge of the diffusion layer 6. In the first embodiment, the diffusion layer 6 includes a high diffusion portion 62 and a low diffusion portion 61.

  The diffusion layer 6 may include one or more portions between the high diffusion portion 62 and the low diffusion portion 61 that have higher light diffusion properties than the low diffusion portion 61 and lower than the high diffusion portion 62. In this case, the change in light diffusibility becomes gentle, and the light emitted from the organic EL element 1 can give a more natural impression to the observer. The details will be described in a first modification described later.

In the first embodiment, the depth dimension H ₂ of the recess 72 in the high diffusion portion 62 is larger than the depth dimension H ₁ of the recess 72 in the low diffusion portion 61. This makes the light diffusion property of the high diffusion part 62 higher than that of the low diffusion part 61. In the first embodiment, the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 is larger than the inclination angle α ₁ of the inclined surface 71 in the low diffusion portion 61. This also makes the light diffusion property of the high diffusion part 62 higher than that of the low diffusion part 61.

The width of the opening of the recess 72 in the diffusion surface 7 is, for example, in the range of 10 nm to 100 μm, and the interval between the adjacent recesses 72 is in the range of, for example, 20 nm to 500 μm. The depth dimension of the recess 72 is preferably in the range of 100 nm to 100 μm. The depth of the shallowest recess 72 in the diffusing surface 7 (i.e., the recess 72 in the low spreading unit 61) relative to the depth H ₁ of the deepest recesses 72 (i.e., the recess 72 in the high diffusion part 62) The ratio value of the dimension H ₂ is preferably in the range of 1.1 to 5.0. In this case, since the light is not diffused excessively in the low diffusion portion 61, high light extraction efficiency is maintained, and in the high diffusion portion 62, the light is sufficiently diffused so that the outline of the light source of the organic EL element 1 is more visually recognized. It becomes difficult to be done.

As shown in FIG. 3, when the diffusion surface 7 includes a plurality of protrusions 73, the width of the protrusion 73 is in the range of 10 nm to 100 μm, for example, and the interval between the adjacent protrusions 73 is in the range of 20 nm to 500 μm, for example. Is within. The height dimension of the protrusion 73 is preferably in the range of 100 nm to 100 μm. In addition, the ratio of the height dimension H ₂ of the protrusion 73 in the high diffusion portion 62 to the height dimension H ₁ of the protrusion 73 in the low diffusion portion 61 may be in the range of 1.1 to 5.0. preferable. In this case, since the light is not diffused excessively in the low diffusion portion 61, high light extraction efficiency is maintained, and in the high diffusion portion 62, the light is sufficiently diffused so that the outline of the light source of the organic EL element 1 is more visually recognized. It becomes difficult.

The inclination angle of the inclined surface 71 in the diffusing surface 7 is preferably in the range of 88 ° to 30 °. Also, most inclination angle is less inclined surface 71 (i.e., the inclined surface 71 in the low spreading unit 61) relative to the inclination angle alpha ₁ of the most inclination angle is larger inclined surface 71 (i.e., the inclined surface 71 in the high diffusion part 62) The value of the ratio of the inclination angle α ₂ is preferably in the range of 1.1 to 2.5. Also in this case, since the light is not diffused excessively in the low diffusion part 61, high light extraction efficiency is maintained, and in the high diffusion part 62, the light is sufficiently diffused, so that the contour of the light source of the organic EL element 1 is further improved. It becomes difficult to see.

  In the first embodiment, it is preferable that the outer peripheral edge of the diffusion layer 6 overlaps the outer peripheral edge of the organic light emitting layer 4 in the direction along the axis X. The outer peripheral edge of the diffusion layer 6 protrudes outside the outer peripheral edge of the organic light emitting layer 4 so that the high diffusion portion 62 of the diffusion layer 6 overlaps the outer peripheral edge of the organic light emitting layer 4 in the direction along the axis X. Is also preferable. In this case, the light emitted from the vicinity of the outer peripheral edge of the organic light emitting layer 4 is strongly diffused, and the contour of the light source of the organic EL element 1 is further hardly recognized.

  The width of the high diffusion portion 62 is preferably 500 μm or less, more preferably 5 μm or less, but is not limited thereto.

  The light absorption of the diffusion layer 6 is preferably low. In this case, the light extraction efficiency from the organic EL element 1 is further improved. For that purpose, it is preferable that the diffusion layer 6 is made of a material having low light absorption. In particular, the extinction coefficient (k) of light in the emission wavelength region of the element body 5 of the diffusion layer 6 is preferably 0.05 or less. In this case, the loss of light is particularly reduced. In order to reduce the light absorption of the diffusion layer 6, the thickness of the diffusion layer 6 is preferably 20 μm or less, and more preferably 10 μm or less.

  The refractive index of the diffusion layer 6 is in the range of 1.3 to 1.5, for example. The diffusion layer 6 is made of, for example, a resin. In this case, the refractive index of the diffusion layer 6 can be easily adjusted, and the diffusion surface 7 can be easily formed on the diffusion layer 6.

  For example, the diffusion layer 6 is formed by molding the resin composition by a coating method. The resin composition may contain a curable resin such as a thermosetting resin or a photocurable resin, or may contain a thermoplastic resin. As resin which a resin composition contains, an acrylic resin, an epoxy resin, a phenol resin etc. are mentioned, for example. Examples of the coating method include a spin coating method, a slit coating method, and an ink jet method, and printing methods such as a gravure printing method and a screen printing method are also included. In the case of the inkjet method and the printing method, it is easy to form the diffusion layer 6 having an appropriate pattern.

  The diffusion layer 6 may be a sheet-like or film-like molded body obtained by molding a synthetic resin. Examples of the synthetic resin include plastic materials such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), acrylic resins, and epoxy resins. Examples of the molding method include rolling molding, roll molding, and injection molding. It is also preferable that the diffusion layer 6 which is a molded body has flexibility. In this case, at the time of manufacturing the organic EL element 1, when the diffusion layer 6 is stacked on the first base material 11, the roll-shaped diffusion layer 6 is fed out and stacked on the first base material 11, for example, by thermocompression bonding or adhesion. , Manufacturing efficiency can be improved. If the diffusion layer 6 has flexibility, it is also possible to obtain the organic EL element 1 having flexibility as a whole.

  The diffusion surface 7 in the diffusion layer 6 is formed by stamping, for example. The diffusion surface 7 may be formed by imprint. In particular, when the diffusion surface 7 is formed by optical imprinting, the diffusion surface 7 is efficiently formed.

  The diffusion layer 6 may contain diffusion particles. The diffusion particles are particles made of a material different from the parent phase of the diffusion layer 6, and more preferably particles having a refractive index different from that of the parent phase of the diffusion layer 6. The light absorption of the diffusing particles is preferably low. By making the diffusion layer 6 contain diffusing particles, it is possible to impart light diffusibility to the diffusion layer 6 or to adjust the light diffusibility of the diffusion layer 6. The diffusing particles may be spherical or lens-shaped. The difference in refractive index between the diffusing particles and the parent phase of the diffusing layer 6 is preferably 0.1 or more. In this case, the light diffusibility of the diffusing layer 6 is further enhanced. The particle diameter of the diffusing particles may be any particle diameter that can diffuse light, but is preferably in the range of 10 nm to 5 μm.

  When the diffusion layer 6 contains diffusion particles, the density of the diffusion particles in the diffusion layer 6 is preferably increased from the central portion of the diffusion layer 6 toward the outer peripheral edge. For example, in the first embodiment, when the low diffusion part 61 does not contain diffusion particles and the high diffusion part 62 contains diffusion particles with a uniform density, the density of the diffusion particles in the diffusion layer 6 is It becomes higher from the central part toward the outer periphery. As a result, the diffusion layer 6 is given a property that its light diffusibility increases from the center of the diffusion layer 6 toward the outer peripheral edge.

  For example, when the diffusion particles exist over the entire diffusion layer 6, the density of the diffusion particles only needs to increase continuously from the central portion of the diffusion layer 6 toward the outer peripheral edge.

  Examples of the diffusion particles include particles containing Ti, Si, or oxides thereof. Further, the diffusing particles may be particles containing a resin having a refractive index different from that of the parent phase of the diffusing layer 6.

  The refractive index of the diffusion layer 6 may be the same as the refractive index of the first electrode 2 or may be lower than the refractive index of the first electrode 2. As an example of a preferable relationship of the refractive index between these layers, there is a relationship in which the refractive index increases in the order of the diffusion layer 6, the first electrode 2, and the organic light emitting layer 4. In this case, since the refractive index gradually changes, the light extraction efficiency of the organic EL element 1 is further improved.

  In the first embodiment, the first base material 11 and the diffusion layer 6 are in contact with each other, but another layer may be interposed between the first base material 11 and the diffusion layer 6. For example, a layer having moisture resistance may be interposed between the first base material 11 and the diffusion layer 6. In this case, the permeation of moisture into the organic light emitting layer 4 is suppressed, and thus the deterioration of the light emission characteristics of the organic light emitting layer 4 is suppressed. In particular, when the first substrate 11 has moisture permeability, it is preferable to provide a layer having moisture resistance. When the moisture-proof layer is provided, the refractive index of the diffusion layer 6 is preferably equal to or lower than the refractive index of the moisture-proof layer. Thereby, the total reflection of the light between the 1st base material 11 and the diffusion layer 6 is further suppressed. For example, the refractive index of the diffusion layer 6 may be lower than that of the moisture-proof layer, and the refractive index may be higher in the order of the diffusion layer 6, the first electrode 2, and the organic light emitting layer 4. It is also preferable that the refractive index of the diffusion layer 6 is equal to or higher than the refractive index of the first electrode 2. Thereby, the total reflection of light between the first electrode 2 and the diffusion layer 6 is further suppressed. For example, the refractive index of the diffusion layer 6 may be lower than that of the moisture-proof layer, and the refractive index of the diffusion layer 6 may be higher than that of the first electrode 2.

  Between the first electrode 2 and the organic light emitting layer 4, an auxiliary electrode 13 made of a conductive material may be superimposed on the first electrode 2. The auxiliary electrode 13 supplements the electrical conductivity of the first electrode 2, improves the current-carrying characteristics of the element body 5, and further uniformizes the current density distribution in the element body 5 to equalize the light emission intensity of the element body 5. can do. The auxiliary electrode 13 is preferably formed from a material having a lower electrical resistance than the first electrode 2. For example, the auxiliary electrode 13 is formed of one or more materials selected from the group consisting of copper, silver, gold, aluminum, nickel, and molybdenum. The auxiliary electrode 13 is preferably formed from a molybdenum / aluminum / molybdenum laminate (Mo / Al / Mo). The auxiliary electrode 13 has, for example, a mesh shape or a lattice shape. The auxiliary electrode 13 is formed, for example, by patterning a material after forming it into a sheet.

  An electric insulating film 14 may be interposed between the auxiliary electrode 13 and the organic light emitting layer 4. Since the auxiliary electrode 13 shields light, even if the portion of the organic light emitting layer 4 that overlaps with the auxiliary electrode 13 emits light, this light is not extracted to the outside, and power loss occurs. The electric loss is suppressed by the electric insulating film 14 preventing the energization of the portion of the organic light emitting layer 4 that overlaps the auxiliary electrode 13. The electrical insulating film 14 can also prevent a short circuit between the auxiliary electrode 13 and the second electrode 3. The electrical insulating film 14 is formed from, for example, a novolac resin, an acrylic resin, or polyimide.

  The auxiliary electrode 13 can apply a force toward the light extraction layer 10 via the first electrode 2. When the electrical insulating film 14 is provided, the electrical insulating film 14 can also apply a force toward the light extraction layer 10 via the auxiliary electrode 13 and the first electrode 2. Therefore, even if the light extraction layer 10 is heated and thermally expanded, the auxiliary electrode 13 presses the light extraction layer 10 to prevent the deformation of the organic EL element 1, and the organic EL element 1 due to cracks at the layer interface or the like. The damage of the is suppressed.

  An auxiliary electrode 13 may be superimposed on the first electrode 2 between the first electrode 2 and the light extraction layer 10. In this case, the electrical insulating film 14 is interposed between the first electrode 2 and the organic light emitting layer 4 at a position overlapping the auxiliary electrode 13 in the direction along the axis X.

  As described above, since light is not extracted from the auxiliary electrode 13 to the outside, the organic EL element 1 may have a portion that does not emit light along the shape of the auxiliary electrode 13. However, in the first embodiment, since the diffusion layer 6 diffuses light, a portion that does not emit light becomes inconspicuous. The portion of the diffusion surface 7 that overlaps the auxiliary electrode 13 in the direction along the axis X is preferably flat. In this case, the auxiliary electrode 13 is easily formed flat, the film quality of the auxiliary electrode 13 is uniform, and the stability is improved. Further, a stable film is easily formed on the auxiliary electrode 13. For this reason, the short circuit in the element body 5 is suppressed, the current density distribution in the element body 5 is stabilized, and the reliability of the organic EL element 1 is improved.

  The second substrate 12 is formed of a material having a low moisture permeability, for example. The second substrate 12 is made of glass, for example. More specifically, the second substrate 12 is made of, for example, soda lime glass or non-alkali glass. The second base material 12 faces the first base material 11 with the element body 5 interposed therebetween. A concave portion may be formed on the opposing surface of the second substrate 12 facing the first substrate 11. In this case, since the element main body 5 is accommodated in the recess, the entry of moisture into the element main body 5 from the outside is suppressed. As the 2nd base material 12 provided with a recessed part, cap glass is used, for example. The opposing surface of the second substrate 12 may be flat. In this case, a dam member surrounding the element body 5 may be interposed between the first substrate 11 and the second substrate 12. preferable. The second substrate 12 may be made of the same material as the first substrate 11, and in this case, even if the first substrate 11 and the second substrate 12 are subjected to heat or stress, the first substrate It becomes difficult for the second substrate 12 to peel from the material 11.

  The first base material 11 and the second base material 12 are joined by an adhesive material 17. Since the adhesive material 17 surrounds the outer periphery of the element body 5, the element body 5 is blocked from the outside and sealed. The adhesive material 17 is a material that functions as an adhesive, and is made of, for example, a resin. The resin adhesive material 17 preferably has moisture resistance, and for that purpose, for example, preferably contains a desiccant. The resin adhesive material 17 may contain a thermosetting resin or an ultraviolet curable resin as a main component.

  A space 18 around the element body 5 sandwiched between the first base material 11 and the second base material 12 in the organic EL element 1 may be a cavity. In this case, the manufacturing process of the organic EL element 1 is simplified. Further, a desiccant may be provided in the cavity. In this case, even if moisture enters the organic EL element 1, the desiccant can absorb the moisture. For example, the desiccant is provided on the surface of the second substrate 12 facing the first substrate 11.

  In addition, the space 18 around the element main body 5 sandwiched between the first base material 11 and the second base material 12 in the organic EL element 1 may be filled with a filler. In this case, even if the second substrate 12 is curved, for example, when the organic EL element 1 is manufactured, the second substrate 12 is prevented from coming into contact with the element body 5, and the organic EL element 1 is manufactured more safely. . The filler is formed from a curable resin composition containing, for example, a desiccant, a hygroscopic agent, and the like. When this resin composition has fluidity, the periphery of the element body 5 is easily filled with the filler. The filler may or may not have curability. When the filler contains a desiccant, a hygroscopic agent, etc., even if moisture enters the organic EL element 1, it becomes difficult for the moisture to reach the element body 5.

  On the first substrate 11, a first wiring 15 and a second wiring 16 that are electrically connected to the element body 5 are provided. The first wiring 15 and the second wiring 16 are made from an appropriate conductive material. One end of the first wiring 15 is connected to the first electrode 2, and the other end is exposed to the outside of the organic EL element 1. One end of the second wiring 16 is connected to the second electrode 3, and the other end is exposed to the outside of the organic EL element 1. The first wiring 15 and the second wiring 16 can be used as terminals for supplying power to the element body 5 from the outside.

  In the first embodiment, since the light extraction layer 10 diffuses the light passing through the light extraction layer 10, total reflection of light in the organic EL element 1 is less likely to occur, thereby improving the light extraction efficiency. Will improve. Further, since the diffusion layer 6 has a property that its light diffusibility increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, light does not diffuse excessively in the central portion of the diffusion layer 6, and thus high light extraction is achieved. Efficiency is maintained, and on the other hand, light is sufficiently diffused in the vicinity of the outer peripheral edge of the diffusion layer 6, so that the outline of the light source of the organic EL element 1 becomes less visible.

  In the first embodiment, the diffusion layer 6 constitutes a part of the light extraction layer 10, thereby reducing the number of members and reducing the cost. The diffusion layer 6 and the light extraction layer 10 may be separate elements. That is, the light emitting device includes a light extraction layer 10 configured to increase the amount of light extracted when the light emitted from the element body 5 is extracted to the outside of the organic EL element 1, and further includes the light extraction layer 10 and Alternatively, a diffusion layer 6 may be provided.

  In the first embodiment, the surface of the diffusion layer 6 that faces away from the first electrode 2 may be the diffusion surface 7. In that case, for example, a recess or protrusion is formed on the first base material 11 by blasting or laser processing, and further, a resin is applied to the first base material 11 to form the diffusion layer 6. Also good. In this case, the surface of the diffusion layer 6 in contact with the first base material 11 becomes the diffusion surface 7.

  When the surface facing the opposite side of the first electrode 2 of the diffusion layer 6 is the diffusion surface 7, the diffusion surface 7 of the diffusion layer 6 and the first base material 11 face each other with a space therebetween, and the diffusion surface 7 and the first surface A filling layer that fills the gap between the base material 11 and the base material 11 may be interposed.

  In the first embodiment, the organic EL element 1 may not include the high refractive index layer 9 and the diffusion layer 6 may be in direct contact with the first electrode 2.

  FIG. 4A and FIG. 4B show a first modification of the first embodiment. In the example shown in FIG. 1A and FIG. 1B, the change in light diffusibility in the diffusion layer 6 is one stage, but in the first modification, the light diffusibility is divided into a plurality of stages in the diffusion layer 6. It has changed.

  In the first modification, the diffusion layer 6 includes an intermediate diffusion portion 63 between the high diffusion portion 62 and the low diffusion portion 61. The middle diffusion portion 63 has a light diffusibility higher than that of the low diffusion portion 61 and lower than that of the high diffusion portion 62. The middle diffusion portion 63 may include a plurality of portions having different light diffusivities.

  In the first modification, the diffusion layer 6 includes the middle diffusion portion 63 in addition to the high diffusion portion 62 and the low diffusion portion 61, so that the light diffusibility changes in a plurality of stages in the diffusion layer 6. For this reason, the change of light diffusibility becomes moderate, and the light emitted from the organic EL element 1 can give a more natural impression to the observer.

When the light diffusibility changes in a plurality of stages in the diffusion layer 6 as in the first modification, the change in the depth dimension of the recess 72 from the central portion of the diffusion layer 6 toward the outer periphery is a plurality of stages. Is preferred. That is, the depth dimension H ₃ of the recess 72 in the middle diffusion part 63 is larger than the depth dimension H ₁ of the recess 72 in the low diffusion part 61, and the depth of the recess 72 in the middle diffusion part 63 is further increased. It is preferable that the depth dimension H ₂ of the recess 72 in the high diffusion portion 62 is larger than the dimension H ₃ .

  In the case where the diffusion surface 7 is provided with a protrusion instead of the recess 72, it is preferable that the change in the height dimension of the protrusion from the central portion of the diffusion layer 6 toward the outer peripheral edge is performed in a plurality of stages. That is, the height dimension of the protrusion in the middle diffusion part 63 is larger than the height dimension of the protrusion in the low diffusion part 61, and further the protrusion in the high diffusion part 62 than the height dimension of the protrusion in the middle diffusion part 63. It is preferable that the height dimension is larger.

The change in the inclination angle of the inclined surface 71 from the central portion of the diffusion layer 6 toward the outer peripheral edge is also preferably in a plurality of stages. In other words, the inclined angle alpha ₁ of the inclined surface 71 in the low diffusion portion 61, larger in inclination angle alpha ₃ of the inclined surface 71 of the middle diffusion unit 63, the inclination angle alpha ₃ of the inclined surface 71 of the middle diffusion unit 63 further It is preferable that the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 is larger than that.

FIG. 5A and FIG. 5B show a second modification of the first embodiment. In the example shown in FIGS. 1A and 1B, the change in the depth dimension of the recess 72 and the change in the inclination angle of the inclined surface 71 in the diffusion surface 7 of the diffusion layer 6 are caused by the light diffusion of the diffusion layer 6. It causes sexual changes. On the other hand, in the second modification, the change in the inclination angle of the inclined surface 71 in the inclined surface 71 of the diffusion layer 6 causes a change in the light diffusibility of the diffusion layer 6. There is no change in the depth dimension at location 72. That is, in the second modified example, since the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 is larger than the inclination angle α ₁ of the inclined surface 71 in the low diffusion portion 61, the light of the high diffusion portion 62 The diffusibility is higher than that of the low diffusion part 61. On the other hand, in the second modification, the depth dimension H ₁ of the recess 72 in the low diffusion part 61 and the depth dimension H ₂ of the recess 72 in the high diffusion part 62 are the same. Even if there is no change in the depth dimension of the recess 72 as in the second modification, a change in the light diffusibility of the diffusion layer 6 can be caused if there is a change in the inclination angle of the inclined surface 71. . Thereby, it becomes difficult to visually recognize the outline of the light source of the organic EL element 1 from the outside.

In the case where the diffusion surface 7 is not provided with the recess 72 but is provided with a protrusion, the change in the inclination angle of the inclined surface 71 causes a change in the light diffusibility of the diffusion layer 6 and the height of the protrusion on the diffusion surface 7 is increased. There is no need to change the size. In this case, since the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 is larger than the inclination angle α ₁ of the inclined surface 71 in the low diffusion portion 61, the light diffusibility of the high diffusion portion 62 is low. It is higher than the diffusion part 61. On the other hand, the height dimension of the protrusion in the low diffusion portion 61 and the height dimension of the protrusion in the high diffusion portion 62 are the same. Thus, even if there is no change in the height dimension of the protrusion, if there is a change in the inclination angle of the inclined surface 71, a change in the light diffusibility of the diffusion layer 6 can be caused. It becomes difficult for the outline of the light source 1 to be visually recognized from the outside.

FIG. 6A and FIG. 6B show a third modification of the first embodiment. In the example shown in FIGS. 1A and 1B, the change in the depth dimension of the recess 72 and the change in the inclination angle of the inclined surface 71 in the diffusion surface 7 change the light diffusibility of the diffusion layer 6. It is generated. On the other hand, in the third modification, the change in the depth dimension of the recess 72 causes a change in the light diffusibility of the diffusion layer 6, but the inclination angle of the inclined surface 71 in the diffusion surface 7 changes. There is no. That is, in the third modified example, since the depth dimension H ₂ of the recess 72 in the high diffusion part 62 is larger than the depth dimension H ₁ of the recess 72 in the low diffusion part 61, the high diffusion part. The light diffusion property of 62 is higher than that of the low diffusion portion 61. On the other hand, in the third modification, the inclination angle α ₁ of the inclined surface 71 in the low diffusion portion 61 and the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 are the same. Even if there is no change in the inclination angle of the inclined surface 71 as in the third modification, a change in the light diffusibility of the diffusion layer 6 can be caused if there is a change in the depth dimension of the recess 72. . Thereby, it becomes difficult to visually recognize the outline of the light source of the organic EL element 1 from the outside.

In the case where the diffusing surface 7 is provided with a protrusion without the recess 72, the change in the height dimension of the protrusion causes a change in the light diffusibility of the diffusing layer 6 and the change in the inclination angle of the inclined surface 71. There is no need. In this case, since the height dimension of the protrusion in the high diffusion part 62 is larger than the height dimension of the protrusion in the low diffusion part 61, the light diffusion property of the high diffusion part 62 is higher than that of the low diffusion part 61. . On the other hand, the inclination angle α ₁ of the inclined surface 71 in the low diffusion portion 61 and the inclination angle α ₂ of the inclined surface 71 in the high diffusion portion 62 are the same. Thus, even if there is no change in the inclination angle of the inclined surface 71, a change in the light diffusibility of the diffusion layer 6 can be caused if there is a change in the height dimension of the protrusion. Thereby, it becomes difficult to visually recognize the outline of the light source of the organic EL element 1 from the outside.

  In the third modification, the diffusing surface 7 may not include the inclined surface 71. That is, the side surface of the recess 72 or the side surface of the protrusion may not be inclined with respect to the axis X. Even in such a case, if there is a change in the depth dimension of the recess 72 or a change in the height dimension of the protrusion on the diffusion surface 7, a change in the light diffusibility of the diffusion layer 6 can be caused. The outline of the light source of the element 1 becomes difficult to be visually recognized from the outside.

  7A and 7B show an organic EL element 1 according to the second embodiment of the present invention.

  The organic EL element 1 according to the second embodiment has the same structure as the organic EL element 1 according to the first embodiment, except that the diffusion layer 6 is divided. Therefore, also in the second embodiment, the light extraction efficiency is improved and the outline of the light source of the organic EL element 1 is not easily recognized as in the first embodiment.

  In the second embodiment, the diffusion layer 6 is divided in a direction orthogonal to the axis X. The axis X is along the direction in which the first electrode 2, the organic light emitting layer 4 and the second electrode 3 are arranged. The axis X usually coincides with the normal line of the surface of the first electrode 2 facing the organic light emitting layer 4.

  The configuration of the diffusion layer 6 in the second embodiment will be described in more detail. The diffusion layer 6 is divided into, for example, a plurality of portions having different light diffusivities, and these portions are arranged such that the light diffusibility of the diffusion layer 6 increases from the central portion toward the outer peripheral edge.

  In the second embodiment, the diffusion layer 6 is divided into a low diffusion portion 61, a middle diffusion portion 63 and a high diffusion portion 62. The middle diffusion portion 63 has higher light diffusibility than the low diffusion portion 61, and the high diffusion portion 62 has higher light diffusibility than the middle diffusion portion 63. In the low diffusion part 61, there is a central part of the diffusion layer 6. The middle diffusion portion 63 surrounds the low diffusion portion 61 with a gap 19 along the outer peripheral edge of the low diffusion portion 61. The high diffusion part 62 surrounds the middle diffusion part 63 with a gap 19 along the outer peripheral edge of the middle diffusion part 63. The outer peripheral edge of the high diffusion portion 62 defines the outer peripheral edge of the diffusion layer 6. These portions may be further divided into a plurality of portions. For example, as schematically shown in FIG. 8, when viewed in the direction along the axis X, the middle diffusion portion 63 divided into a plurality of portions surrounds the low diffusion portion 61 and is further divided into a plurality of portions. The diffusion unit 62 may surround the middle diffusion unit 63.

  When the diffusion layer 6 is divided into a plurality of portions in this way, the diffusion layer 6 is not easily damaged even when heat or force is applied to the diffusion layer 6.

  Also in the second embodiment, as in the first embodiment, the auxiliary electrode 13 is superimposed on the first electrode 2 and an electrical insulating film 14 is further provided. It is preferable that the auxiliary electrode 13 and the gap 19 generated by dividing the diffusion layer 6 overlap each other in the direction along the axis X. Since the auxiliary electrode 13 blocks light, no light is extracted from the auxiliary electrode 13 to the outside. For this reason, it is not necessary to diffuse light at a position overlapping with the auxiliary electrode 13. By disposing the gap 19 in the diffusion layer 6 at a position overlapping the auxiliary electrode 13, the diffusion layer 6 is divided without impairing the performance of the diffusion layer 6.

  When the auxiliary electrode 13 and the gap 19 overlap with each other in the direction along the axis X, a plurality of portions (low diffusion portion 61, medium diffusion portion 63, high diffusion) generated by the diffusion layer 6 being further divided. It is preferable that the light diffusibility of each of the portions 62 and the like (hereinafter referred to as divided portions) is higher toward the gap 19 in contact with each divided portion. In this case, since the light is diffused strongly in the vicinity of the auxiliary electrode 13, the dark portion generated by the auxiliary electrode 13 in the organic EL element 1 becomes inconspicuous. In order for the light diffusibility of each divided portion to increase toward the gap 19 in contact with each divided portion, for example, in the entire diffusion layer 6, the depth dimension of the recess 72 in the diffusion surface 7 is the center of the diffusion layer 6. The inclination angle of the inclined surface 71 in each divided portion increases toward the gap 19 from the portion toward the outer peripheral edge. In the diffusion layer 6 as a whole, the inclination angle of the inclined surface 71 in the diffusion surface 7 increases from the central portion of the diffusion layer 6 toward the outer peripheral edge, and the depth dimension of the recess 72 in each divided portion is a gap. You may become large toward 19.

  The organic EL device 1 according to the third embodiment of the present invention is shown in FIGS. 9 (a) and 9 (b). The organic EL element 1 according to the third embodiment does not include the light extraction layer 10 in the first embodiment. That is, the light extraction layer 10 is not interposed between the first electrode 2 and the first base material 11.

  In the third embodiment, the diffusion layer 6 is superimposed on the surface of the first base material 11 opposite to the surface facing the first electrode 2. For this reason, the diffusion layer 6 is exposed to the outside of the organic EL element 1. The diffusion surface 7 of the diffusion layer 6 faces the side opposite to the first electrode 2.

  The diffusion layer 6 is formed, for example, by molding a resin composition by a coating method. The diffusion layer 6 may be a sheet-like or film-like molded body obtained by molding a synthetic resin. The diffusion layer 6 can be manufactured using the same material as that of the diffusion layer 6 in the first embodiment, for example, and in the same manner as in the case of manufacturing the diffusion layer 6 in the first embodiment.

The diffusion layer 6 has a property that its light diffusibility increases stepwise from the central portion of the diffusion layer 6 toward the outer peripheral edge. In the third embodiment, the diffusion layer 6 includes a high diffusion portion 62 and a low diffusion portion 61. In the third embodiment, the depth dimension H ₂ of the recess 72 in the high diffusion portion 62 is larger than the depth dimension H ₁ of the recess 72 in the low diffusion portion 61. This makes the light diffusion property of the high diffusion part 62 higher than that of the low diffusion part 61. In the third embodiment, the inclination angle α ₂ with respect to the axis X of the inclined surface 71 in the high diffusion portion 62 is larger than the inclination angle α _{1 with} respect to the axis X of the inclined surface 71 in the low diffusion portion 61. This also makes the light diffusion property of the high diffusion part 62 higher than that of the low diffusion part 61.

  In the third embodiment, as in the first embodiment, by providing the diffusion layer 6, the degree of diffusion of light that passes through the vicinity of the outer peripheral edge of the first electrode 2 and exits to the outside increases. When the organic EL element 1 is observed from the outside, the outline of the organic light emitting layer 4 that is a light source becomes difficult to be visually recognized. On the other hand, since the degree of diffusion of the light that passes through the central portion of the first electrode 2 and is emitted to the outside is smaller than that in the vicinity of the outer peripheral edge, a decrease in light extraction efficiency is suppressed. For this reason, the fall of the light extraction efficiency which is easy to occur with the improvement of light diffusibility is suppressed.

  Furthermore, since the diffusion layer 6 can be provided so as to be exposed to the outside of the organic EL element 1, it is easy to additionally provide the diffusion layer 6 in the organic EL element 1 that does not include the diffusion layer 6.

  In FIG. 10, the example of the lighting fixture 100 provided with the organic EL element 1 is shown. The lighting fixture 100 includes an organic EL element 1 and a fixture main body 110 that holds the organic EL element 1. The instrument main body 110 includes a housing 111, a front panel 112, wiring 113, and a power supply terminal 114.

The casing 111 is configured to hold the organic EL element 1. The housing 111 includes a recess 115, and the organic EL element 1 is held in the recess 115. The opening of the recess 115 is closed by the front panel 112. The front panel 112 is provided with a front case 116 and a rear case 117 in a recess 115 of the translucent casing 111. The organic EL element 1 is held between the front side case 116 and the back side case 117. The front side case 116 is interposed between the first base material 11 and the front panel 112. The front side case 116 includes an opening 118 facing the first base material 11 of the organic EL element 1.

  Two wirings 113 are provided from the outside to the inside of the housing 111. These two wirings 113 are connected to an external power source. Two power supply terminals 114 are sandwiched and fixed between the front side case 116 and the back side case 117. The two wirings 113 are connected to the two power supply terminals 114, respectively, and the two power supply terminals 114 are connected to the first wiring 15 and the second wiring 16, respectively. Thus, power is supplied from an external power source to the element body 5 in the organic EL element 1 through the wiring 113 and the power supply terminal 114.

  In this luminaire 100, when power is supplied from an external power source to the element body 5 in the organic EL element 1 via the wiring 113 and the power supply terminal 114, the element body 5 emits light, and this light is transmitted to the first base material. 11, and exits through the opening 118 and the front panel 112.

DESCRIPTION OF SYMBOLS 1 Organic EL element 2 1st electrode 3 2nd electrode 4 Organic light emitting layer 6 Diffusion layer 7 Diffusion surface 72 Recess 100 Lighting fixture

Claims (7)

A first electrode having a planar shape and having optical transparency;
A second electrode paired with the first electrode;
An organic light emitting layer disposed between the first electrode and the second electrode;
The light emitted from the organic light emitting layer through the vicinity of the outer peripheral edge of the first electrode to the outside is diffused more than the light emitted from the organic light emitting layer through the central portion of the first electrode to the outside. A diffusion structure composed of
An organic electroluminescence device comprising: A diffusion layer disposed at a position opposite to the organic light emitting layer with respect to the first electrode,
The diffusion layer defines the diffusion structure;
The diffusion layer is configured to transmit and diffuse light passing through the first electrode, and the light diffusibility of the diffusion layer increases from the central portion of the diffusion layer toward the outer periphery.
The organic electroluminescent element according to claim 1. The diffusion layer includes a diffusion surface facing the first electrode or facing the opposite side of the first electrode,
The diffusion surface comprises a plurality of recesses or a plurality of protrusions,
The depth dimension of the recess or the height dimension of the protrusion is increased from the central portion of the diffusion layer toward the outer peripheral edge,
The organic electroluminescent element according to claim 2. A high refractive index layer disposed between the diffusion layer and the first electrode and having a higher refractive index than the diffusion layer;
The diffusion surface is opposed to the first electrode;
The high refractive index layer is in contact with the diffusion surface of the diffusion layer;
The organic electroluminescent element according to claim 3. The diffusion layer contains diffusion particles,
The density of the diffusion particles increases from the center of the diffusion layer toward the outer periphery.
The organic electroluminescent element as described in any one of Claims 2 thru | or 4. The diffusion layer is divided in a direction orthogonal to an axis along a direction in which the first electrode, the organic light emitting layer, and the second electrode are arranged.
The organic electroluminescent element as described in any one of Claims 2 thru | or 5. A lighting fixture comprising: the organic electroluminescence device according to any one of claims 1 to 6; and a fixture main body that holds the organic electroluminescence device.

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