JP2016100297A - Transparent substrate for el element, organic el illumination, organic el light source, and organic el display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL element, requiring no special device such as a high-temperature sintering furnace, versatile, capable of reducing the number of manufacturing steps, having no quality problem such as crack generation, excellent in light extraction efficiency.SOLUTION: A transparent substrate 4, on which a positive electrode 3, a light-emitting layer 2, a negative electrode 1 are subsequently laminated, for an EL element, is provided by a multilayer extrusion method or a thermal lamination method on a surface or inside with a total reflection preventing surface 11a, on one surface, having a light extraction function, and on the other surface a smooth surface for forming an EL surface.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an organic EL (Electro Luminescence / electroluminescence) element, and more particularly to a transparent substrate for an EL element with improved light extraction efficiency of the organic EL element.

  Organic EL elements have been applied to displays for mobile phones and digital cameras, and to lighting devices because of their advantages such as wide viewing angle due to self-emission, high-speed response, and thin and light weight.

  FIG. 8 shows a configuration of a general organic EL element and a light extraction state in the organic EL element. On the transparent substrate 4, the anode 3, the hole injection layer, the hole transport layer, the interlayer layer, the light emission. It has a structure in which a layer 2, an electron transport layer, an electron injection layer, and a cathode 1 are sequentially laminated. A DC voltage is applied to the anode 3 and the cathode 1, and electrons and holes are injected into the light emitting layer 2. Excitons are generated by recombination, and light emission occurs by utilizing the emission of light when the excitons are deactivated.

  In the configuration of a general organic EL element, when light rays emitted from the light emitting layer 2 are emitted from the transparent substrate on the light emitting surface side, some of the light rays may be at the interface between the transparent substrate 4 on the observation side and air, or the anode 3. There is a problem that the total amount of light reflected at the interface between the transparent substrate 4 and the transparent substrate 4 is lost.

  In this case, it is said that the light extraction efficiency of the amount of light extracted outside is generally about 20%. Therefore, it is necessary to increase the input power as the display and illumination with high brightness are required. In this case, since a large current flows through the element, the load on the element increases, resulting in a decrease in luminance and a reduction in lifetime, and the reliability of the element itself decreases.

  In response to this problem, various attempts have been made to increase the light extraction efficiency of the organic EL element. FIG. 9 shows a configuration in which a light extraction film 5 having a lens shape is attached to the outside of the transparent substrate 4. An attempt has been reported to reduce the light 8a emitted from the organic light emitting layer and totally reflected at the transparent substrate-air interface, and to increase the light 8b emitted from the organic light emitting layer and exiting without being totally reflected. Yes.

  FIG. 10 shows a configuration in which a light scattering layer is inserted between a transparent electrode such as ITO as an anode and a transparent substrate, and light 9a emitted from the organic light emitting layer and totally reflected at the transparent substrate-anode interface is shown. There has been reported an attempt to reduce the amount of light 9b emitted from the organic light emitting layer and exiting to the outside without being totally reflected at the total reflection preventing surface-anode interface.

  Conventionally, the mainstream method is to attach a light extraction film 5 having a lens shape to the outside of the transparent substrate 4 to improve the light extraction efficiency. However, it is possible to extract light that is totally reflected between the anode and the transparent substrate. However, since the amount of the extracted light to the outside increases, the method of inserting a light scattering layer between the anode and the translucent substrate has been attracting attention in recent years.

  As the method, for example, a glass frit kneaded together with a resin is applied onto a glass substrate, and the glass frit is melted and the resin is burned off by baking and heating at a high temperature, and the bubbles are made into a glass medium. There is a report of a method of making it internal (Patent Document 1).

However, since firing at 500 ° C. or higher is necessary for melting the glass frit, there is a problem in that heat energy consumption is large, plastic material cannot be applied as a substrate, and versatility is poor. There is also a problem in productivity in that a high temperature sintering furnace is required.

  Moreover, a method for obtaining a scattering layer by spin coating an acrylic resin solution containing zinc oxide as scattering particles has been reported (Patent Document 2).

  However, the point of obtaining a light scattering layer by applying a resin solution by spin coating and then drying at a temperature around the boiling point of the solvent is preferable because the heat energy consumption is small, but because it is sheet-to-sheet processing, it is mass-productive. Have a problem of lacking.

  Also, a method of obtaining a cured film that functions as a light scattering layer by applying a mixture of a sol-gel solution that is a hydrolyzate of tetraethoxysilane and a silica sol solution having a particle size of 80 nm by spin coating and heating at 300 ° C. has been reported. (Patent Document 3).

  However, it is an easy formation method by coating, and is preferable in that a film having high heat resistance is obtained. However, a cured film formed from a sol-gel solution of a metal alkoxide has a shrinkage stress at the time of curing as the film thickness increases. In order to introduce scattering particles having a particle size of several tens of nanometers or more effective for visible light scattering into a film of 200 nm or less, which has an effective film thickness where cracks are generated and cracks do not occur, the amount is limited. Therefore, the function as a light scattering layer may be inferior. Furthermore, since this light-scattering film is an inorganic glass material and has low flexibility and is not suitable for a flexible substrate material, there is a problem that it is inferior in versatility.

  As means for solving these problems, it has been proposed to apply a porous cured product obtained by curing a composition containing polysilane, metal oxide, and solvent as a light scattering layer (Patent Document 4).

  However, the porous light scattering layer is formed by heating at a high temperature of about 400 ° C. in order to remove the solvent, and the heat energy consumption required for production is large although not as high as the firing.

  In both cases, there is a process to apply and heat a liquid containing light scattering elements on the substrate, so there is a limit to downsizing the device and reducing the number of processes, limiting the shape of the light extraction layer There is also a problem that occurs.

JP 2011-248104 A International Publication No. 2009/116531 JP 2010-182449 A International Publication No. 2003/26357

  The present invention has been made in view of the above problems, does not require a special device such as a high-temperature sintering furnace, is versatile, can reduce the number of manufacturing steps, and has a quality such as generation of cracks. It is an object of the present invention to provide an organic EL element with good light extraction efficiency.

As means for solving the above-mentioned problems, the invention according to claim 1 includes an anode, a hole injection layer, a hole transport layer, an interlayer layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode sequentially. A transparent substrate for EL elements to be laminated,
A transparent substrate for an EL element, wherein a total reflection preventing surface having a light extraction function is provided on the surface or inside by a multilayer extrusion method or a thermal lamination method.

  According to a second aspect of the present invention, in the transparent EL element according to the first aspect, the total antireflection surface is formed of a light scattering element made of scattering particles or a lens-like shape. It is a substrate.

  The invention according to claim 3 is an uneven structure in which the surface on the anode side has a height of 100 to 800 nm and an aspect ratio falls within a range of 1 to 3. 2. A transparent substrate for an EL device according to 2.

  The invention according to claim 4 is characterized in that the arithmetic mean roughness Ra of the surface on the anode side is 2.5 nm or less, for EL elements according to any one of claims 1 to 3. This is a transparent substrate.

  The invention according to claim 5 is characterized in that the total reflection preventing surface is provided on a surface which does not contact the anode of a transparent substrate for an EL element. It is a transparent substrate for EL elements as described in the paragraph.

  The invention according to claim 6 is characterized in that the total reflection preventing surface is provided on a surface in contact with the anode of a transparent substrate for an EL element. It is a transparent substrate for EL elements as described in above.

  The invention according to claim 7 is characterized in that the total reflection preventing surface is provided on both surfaces of a transparent substrate for an EL element. It is a transparent substrate for elements.

  In the invention according to claim 8, the light extraction function of the total reflection preventing surface having the light extraction function is expressed by the shape of the substrate, that is, the total reflection preventing surface has a lens shape. It is a transparent substrate for EL elements as described in any one of Claims 1-7 characterized by the above-mentioned.

  The invention according to claim 9 is an organic EL illumination using the transparent substrate for an EL element according to any one of claims 1 to 8.

  The invention according to claim 10 is an organic EL light source characterized by using the transparent substrate for an EL element according to any one of claims 1 to 8.

  The invention according to claim 11 is an organic EL display device using the organic EL light source according to claim 10.

According to the present invention, it is possible to provide an organic EL element, a luminaire, a light source, and a display device that are more versatile than conventional ones, can reduce the number of manufacturing steps, and have good light extraction efficiency.
Further, the surface of the organic EL element can be extended by having a surface roughness suitable for forming a water vapor barrier film.

It is the schematic cross section which showed the structure of the EL element using the transparent substrate for EL elements which provided the total reflection prevention surface concerning this invention. It is the schematic cross section which showed one structure of the transparent substrate for EL elements which provided the total reflection prevention surface concerning this invention. It is the schematic cross section which showed one structure of the transparent substrate for EL elements which provided the total reflection prevention surface concerning this invention. It is the schematic cross section which showed another structure of the transparent substrate for EL elements which provided the total reflection prevention surface concerning this invention. FIG. 3 is a schematic diagram illustrating a manufacturing method related to FIG. 2 in which a conical total reflection preventing surface is formed on the electrode side surface of the transparent substrate and a lens shape is imparted to the irradiation side surface of the transparent substrate. FIG. 4 is a schematic diagram illustrating a manufacturing method related to FIG. 3 and forming a lens-shaped total antireflection surface on the irradiation side surface of the transparent substrate. FIG. 5 is a schematic diagram illustrating a manufacturing method related to FIG. 4, in which a molten resin is discharged onto a shaped sheet and a lens-shaped total antireflection surface is formed inside a transparent substrate. It is the cross-sectional schematic diagram which showed the structure of a general organic EL element, and the light emitted from a light emitting layer and totally reflected in a transparent substrate-air interface and a transparent substrate-anode interface. It is the cross-sectional schematic diagram which showed the mode of the light discharge | released from a light emitting layer in the transparent substrate-air interface at the time of sticking the light extraction film 19 on the irradiation side surface of the transparent substrate 4. FIG. It is the cross-sectional schematic diagram which showed the mode of the light discharge | released from a light emitting layer in the transparent substrate-anode interface at the time of sticking the light extraction film 20 on the transparent substrate 4 electrode side surface.

  DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings. Note that the shape will be described with reference to the drawings, but the same or similar functions are denoted by the same reference numerals throughout the drawings, and redundant description will be omitted. Further, the shape is merely a reference example, and is not limited to the illustrated shape, and can be appropriately selected according to a desired application / performance. Furthermore, each figure is a schematic diagram, and the scale of each part does not coincide with the actual scale.

  FIG. 1 shows a substrate example 1 according to the present invention, in which a microlens-shaped total reflection preventing surface 5 is formed on the light emitting surface side of the core material 10 and a conical total reflection preventing surface 6 is formed on the other electrode side surface. A configuration in which an EL element is formed by laminating an anode 3, a light emitting layer 2, and a cathode 1 thereon is shown.

  Examples of the material of the substrate provided on the light emitting surface side according to the present invention include PET (Polyethylene terephthalate), polycarbonate, and PEN (Polyether nitrile), but are not limited thereto and can be arbitrarily selected.

  FIG. 2 shows the configuration of the substrate example 1 according to the present invention.

  FIG. 3 shows a substrate example 2 according to the present invention, and shows a configuration in which a microlens-shaped total reflection preventing surface 5 is formed on the light emitting surface side of the core material 10.

  FIG. 4 shows a substrate example 3 according to the present invention, and shows a configuration in which a conical total reflection preventing surface 6 is formed on the electrode side surface of the core material 10. The electrode side surface of the core material 10 needs to be smooth, and by providing a resin layer in which light scattering particles are kneaded and laminated by coextrusion, the surface is smooth and a total reflection preventing function can be imparted.

  The part having the light extraction function composed of the microlens-like total antireflection surface 5 and the conical total antireflection surface 6 is integrated with the transparent substrate without undergoing a coating process or a bonding process via an adhesive or adhesive layer. It is characterized by being.

FIG. 5 is a schematic diagram illustrating a manufacturing method related to FIG. 1, in which a microlens-like total antireflection surface 5 is formed on one surface of a transparent substrate and a conical total antireflection surface is formed on the other surface. The resin 10b forming the core material and the resin 11b forming the total antireflection surface forming the microlens-like total antireflection surface are heated and melted to form a total antireflection surface having a conical shape on the surface. The surface of the shaping sheet 12 is co-extruded from the T-die 14 and passes between the first clamping roll 15 and the second clamping roll (for shaping) 16 a, and the first cooling roll 17 and the second cooling roll 18. The substrate example 1 according to the present invention in which the micro-lens-like total antireflection surface 5 is formed on one surface and the anode side surface having the conical total antireflection surface inside the other surface is flat is formed. .

  FIG. 6 is a schematic diagram illustrating a manufacturing method for forming the microlens-like total antireflection surface 5 on one surface of the transparent substrate in relation to FIG. 3, and is a resin 10 b that forms a core material and a resin that forms a surface layer. 11 b is heated and melted, co-extruded from the T die 14, passes between the first pinching roll 15 and the second pinching roll (for shaping) 16 a, and is cooled by the first cooling roll 17 and the second cooling roll 18. The substrate example 2 according to the present invention having the microlens-like total antireflection surface 5 is formed by cooling.

  FIG. 7 is a schematic diagram for explaining a manufacturing method for forming a conical total antireflection surface on one side of a transparent substrate in relation to FIG. 4, and the resin 10 b forming the core material is heated and melted to form a T die. 14, passed between the first pinching roll 15 and the second pinching roll (flat roll) 16 b, cooled by the first cooling roll 17 and the second cooling roll 18, and on the electrode side surface of the transparent substrate A substrate example 3 according to the present invention in which a conical total antireflection surface is formed is formed.

  Moreover, it is also possible to peel and use the shaping sheet | seat 12 which forms a total reflection prevention surface.

  As a method for imparting the shape of the total antireflection surface having a microlens shape or the conical total antireflection surface, the method of pinching with the second pinching roll (for shaping) 16a as described above, or the shaping sheet 12 is used. In addition to pouring the molten resin into the sheet, it is possible to select a method of transferring a desired shape by pressing a heated die during conveyance of a sheet formed by pressing with a flat roll, but the tip becomes narrower. This is not desirable because there is a risk of incomplete transfer due to the shape or the possibility of residual distortion and color unevenness.

  When forming on both sides with a pinching roll, if the shape size is several to several tens of μm on both sides (shape size as a light extraction function provided on the outermost surface), there is a risk of inconvenience such as thickness variation. However, since the transparent substrate for an EL element according to the present invention is designed to have at least one surface of less than 1 μm as described later, it can be manufactured without causing unevenness in thickness or imperfect shape transfer. Since a cooling process is provided later, residual distortion can be eliminated.

  As described above, the total antireflection surface can be provided without undergoing a coating process or a bonding step via an adhesive or adhesive layer, and the core material 10 and the resin 11b forming the total antireflection surface are integrated. By adjusting the smoothness of the pinching roll, while maintaining the surface smoothness equivalent to the coated surface, there is no repellency at the time of coating, no lifting / peeling, the performance maintenance period is long, and the number of substrate processing steps It is possible to provide a transparent substrate for an EL element that leads to reduction in the type, manpower and cost of the processing machine.

  Furthermore, by adjusting the molding speed at the time of extrusion molding and the supply amount of the raw material resin, it is possible to easily obtain substrates having the same configuration and different thicknesses, and to give flexibility or rigidity. It becomes possible.

It is also advantageous in that it can be easily processed to a thickness according to the application, and when a base material is molded as a flexible film, it becomes possible to collect and recover, so that the subsequent process can be processed with roll-to-roll, It is also advantageous in that mass production is possible. The resin used as a raw material does not need to be a single product, and may be a laminate of different refractive index resins by coextrusion, or a light scattering layer in which light scattering particles are mixed may be provided. Further, the substrate examples 1 to 3 are merely examples, and the number of co-extrusion layers may be three or more depending on the design.

  On the other hand, when a concave / convex structure having a height of 100 to 800 nm and an aspect ratio in the range of 1 to 3 is imparted to the surface in contact with the electrode, it is disadvantageous for the formation of a water vapor barrier by vapor deposition. It has also been found that by following up to the formation of the electrode on the opposite side, plasmon loss can be reduced, leading to an improvement in light extraction efficiency. Which performance is prioritized may be appropriately determined according to the specifications required by the product.

  When the light scattering layer is formed on the outermost surface on the electrode side, it is difficult to adjust the surface roughness and the surface shape. Therefore, when providing the light scattering layer, it is desirable to avoid the outermost surface on the electrode side.

  The total light transmittance of the entire substrate provided on the light emitting surface side is desirably 80% or more. This is because when the total light transmittance is less than 80% due to absorption or reflection by the resin or light-scattering particles used for the substrate, the amount of light of the organic EL element decreases, and sufficient brightness cannot be maintained. This is because it is disadvantageous. When the total light transmittance is 80% or more, the light emitted from the light emitting layer can be effectively utilized.

  Hereinafter, it demonstrates in detail based on an Example.

  By the manufacturing method shown in FIG. 6, flexible PEN (manufactured by Teijin Ltd.) is extruded as a core substrate so as to have a thickness of 600 μm, and the surface of the electrode side surface has a surface roughness Ra of the first pinching roll (for flattening). A transparent substrate for an EL element of Example 1 was obtained by a mold roll having a microlens matrix in contact with 2.0 nm. In order to provide a water vapor barrier on the surface, a sputtered film of SiON having a thickness of 30 nm was provided.

  A transparent substrate for an EL element of Example 2 was obtained under the same conditions as Example 1 except that the surface roughness Ra of the second pinching roll (for flattening) was 2.5 nm.

  In this embodiment, a light scattering layer is inserted into the inside of Example 2, and in the manufacturing method shown in FIG. 6, the number of coextrusions is 3, and the resin for forming the surface layer is used without adding filler on both sides, and the central layer Was added with a silicone particle (manufactured by Momentive) having a diameter of φ0.8 um as a light scattering material in a range of 10 to 25% to form a light scattering layer. The base resin is PEN (manufactured by Teijin Ltd.), the surface layer is adjusted to a thickness of 100 to 150 μm, the light scattering layer is adjusted to a thickness of 300 to 400 μm, and the surface roughness Ra of the second pinching roll (for flattening). Was set to 2.5 nm, and a transparent substrate for an EL device of Example 3 was obtained under the same conditions as in Example 2.

  A transparent substrate for the EL element of Example 4 was obtained under the same conditions as in Example 1 except that rigid PEN (manufactured by Teijin Ltd.) was extruded to a thickness of 3 mm as the core substrate used in Example 1. It was.

  A transparent substrate for the EL element of Example 5 was obtained under the same conditions as in Example 1 except that rigid PEN (manufactured by Teijin Ltd.) was extruded to a thickness of 3 mm as the core substrate used in Example 2. It was.

A transparent substrate for the EL element of Example 6 was obtained under the same conditions as in Example 1 except that rigid PEN (manufactured by Teijin Ltd.) was extruded to a thickness of 3 mm as the core substrate used in Example 3. It was.

  Transparent for the EL element of Example 7 under the same conditions as in Example 6 except that a smooth roll was used instead of the mold roll having the microlens matrix used on the light exit surface side of Example 6. A substrate was obtained.

  In Example 3, the coextrusion number was set to 2, and instead of omitting the surface layer resin opposite to the mold roll, as shown in FIG. 4, the same conditions except that a 90 ° prism sheet was inserted as the shaping sheet 12. A transparent substrate for the EL device of Example 8 was obtained.

  As the same core base material as in Example 4, rigid PEN (manufactured by Teijin Ltd.) was extruded so as to have a thickness of 3 mm, and the surface of the electrode side surface had a conical matrix with a conical height of 100 nm and an aspect ratio of 1, A transparent substrate for the EL element of Example 9 was obtained by using a pinching roll (for shaping) 16a and a light emitting surface using a smooth roll. The surface is not provided with a sputtered SiON film for providing a water vapor barrier.

  A transparent substrate for the EL element of Example 10 was used under the same conditions as Example 9 except that the smooth roll used on the light emission surface side of Example 9 was replaced with a mold roll having a microlens matrix. Obtained. The surface is not provided with a sputtered SiON film for providing a water vapor barrier.

  Example 11 was carried out under the same conditions as Example 9 except that a second pinching roll (for shaping) 16a having a cone-shaped matrix with a cone height of 100 nm and an aspect ratio of 3 was used for forming the surface of the electrode side surface. A transparent substrate for an EL element was obtained. The surface is not provided with a sputtered SiON film for providing a water vapor barrier.

  Example 12 was performed under the same conditions as Example 9 except that a second pinching roll (for shaping) 16a having a cone-shaped matrix with a cone height of 350 nm and an aspect ratio of 1 was used to form the electrode side surface. A transparent substrate for an EL element was obtained. The surface is not provided with a sputtered SiON film for providing a water vapor barrier.

  Example 13 was carried out under the same conditions as in Example 9, except that a second pinching roll (for shaping) 16a having a cone-shaped matrix with a cone height of 800 nm and an aspect ratio of 1 was used to form the electrode side surface. A transparent substrate for an EL element was obtained. The surface is not provided with a sputtered SiON film for providing a water vapor barrier.

<Comparative Example 1>
The EL of Comparative Example 1 was performed under the same conditions as in Example 1 except that the surface roughness Ra of the second sandwiching roll for surface formation (for flattening) on the electrode side surface used in Example 1 was set to 3.0 nm. A transparent substrate for the element was obtained.

<Comparative Example 2>
A water vapor barrier was not provided, and the other conditions were the same as in Example 1, and a transparent substrate for an EL element of Comparative Example 2 was obtained.

<Comparative Example 3>
A water vapor barrier was not provided, and the other conditions were the same as in Example 2, and a transparent substrate for an EL element of Comparative Example 3 was obtained.

<Comparative example 4>
The surface roughness Ra of the second pressure forming roll (for flattening) on the side surface of the electrode used in Example 1 is set to 3.0 nm, no water vapor barrier is provided, and other conditions are the same as in Example 1. As a result, a transparent substrate for an EL element of Comparative Example 4 was obtained.

<Comparative Example 5>
The EL of Comparative Example 5 was carried out under the same conditions as in Example 4 except that the surface roughness Ra of the second pinching roll for surface formation (for flattening) on the electrode side surface used in Example 4 was set to 3.0 nm. A transparent substrate for the element was obtained.

<Comparative Example 6>
A transparent substrate for an EL element of Comparative Example 6 was obtained under the same conditions as in Example 4 except that a SiON sputtered film for providing a water vapor barrier was not provided on the surface.

<Comparative Example 7>
A transparent substrate for an EL device of Comparative Example 7 was obtained under the same conditions as in Example 5 except that a sputtered SiON film for providing a water vapor barrier on the surface was not provided.

<Comparative Example 8>
A transparent substrate for an EL element of Comparative Example 8 was obtained under the same conditions as Comparative Examples 6 and 7, except that the surface roughness Ra of the second pinching roll (for flattening) was 3.0 nm.

<Comparative Example 9>
The surface of the electrode side surface is the same as in Example 9 except that a second pinching roll (for shaping) 16a having a conical shape with a cone height of 50 nm and an aspect ratio of 1 is used. A transparent substrate for an EL element was obtained.

<Comparative Example 10>
The surface of the electrode side surface is the same as in Example 10 except that a second pinching roll (for shaping) 16a having a conical shape with a cone height of 900 nm and an aspect ratio of 1 is used. A transparent substrate for an EL element was obtained.

  In order to confirm the effect of the present invention, various organic EL elements having a cathode (silver) / light emitting layer / anode (ITO if the transparent substrate is rigid, conductive polymer PEDOT / PSS (Aldrich) if the transparent substrate is flexible) / transparent substrate configuration At this time, the anode = ITO, the transparent substrate = rigid glass, and a configuration in which a microlens was bonded as a light extraction film on the light exit surface was used as a reference.

<Evaluation>
The produced organic EL device was evaluated from the viewpoint of the number of steps, light extraction efficiency, life, and substrate strength.

<Number of steps>
The evaluation criteria were ○ if the number of manufacturing steps was less than that of the reference, and × if it was more.

<Light extraction efficiency>
In the measurement using an integrating sphere, the total luminous flux was greater than that of the reference, ◯, if equal, Δ, and x if less.

<Light emitting layer lifetime>
If the time until the occurrence of TL70 or a dark spot is longer than the reference, it is indicated as ◯, if it is equal, Δ, and if it is shorter, it is indicated as x.

<Board strength>
A drop test and heating at 80 ° C. for 24 hours were performed, and evaluation was performed by floating and peeling. If the result was better than that of the reference, the result was ○, if it was the same, Δ, and if it was bad, the result was ×.

  The results are shown in Table 1.

  It can be seen from Examples 1 and 2 and Comparative Examples 2 and 3 that the lifetime of the light emitting layer was deteriorated by the presence or absence of the water vapor barrier.

  From the results of Examples 4 and 5 and Comparative Examples 6 and 7, it can be seen that the lifetime of the light emitting layer is improved by the presence or absence of the sputtered SiON film.

  Comparative Example 1 and Comparative Example 5 show that even when the water vapor barrier layer is provided, the life is adversely affected when the surface roughness Ra on the side where the electrode is provided is 3.0 nm.

  From the results of Examples 6 and 8, it was found that the light extraction efficiency equivalent to that obtained when the microlens sheet was bonded to the outside of the glass substrate was obtained when the microlens was provided on the irradiation side surface.

  By selecting resin as the material of the base material provided on the light emitting surface, there remains a concern that the deterioration of the element due to water vapor is faster than when glass is used, but the surface roughness Ra on the side where the electrode is provided is 2 By setting the thickness to 5 nm or less, it is advantageous for vapor deposition of the water vapor barrier film, and by providing the water vapor barrier film between the substrate and the electrode, the lifetime is longer than when the device is manufactured without paying attention to the surface roughness. It turns out that it becomes possible.

  From Examples 9, 12, and 13 and Comparative Examples 9 and 10, the light extraction efficiency is improved by forming a concavo-convex structure with an aspect ratio of 1 and a height of 100 to 800 nm on the electrode side surface of the transparent substrate. I understand that.

  According to the present invention, in an organic EL element composed of a cathode, an anode, and an organic EL layer sandwiched between them, a part having a light extraction function can be provided without using coating or adhesion. Thus, it can be seen that the number of manufacturing steps can be reduced, and a transparent substrate for an EL element with good light extraction efficiency can be obtained.

  Moreover, it was confirmed that the transparent substrate was the same regardless of whether it was rigid or flexible, and it was rich in versatility.

DESCRIPTION OF SYMBOLS 1 ... Cathode 2 ... Light emitting layer 3 ... Anode 4 ... Transparent substrate 5 ... Microlens-like total reflection preventing surface 6 ... Light scattering layer 7 ... Emission from organic light emitting layer The light 8a not totally reflected between the organic light emitting layer-anode and the anode-transparent substrate is emitted from the organic light emitting layer, the light 8b totally reflected at the transparent substrate-air interface is emitted from the organic light emitting layer, Light 9a exiting outside without total reflection ... Light emitted from the organic light emitting layer and totally reflected at the transparent substrate-anode interface 9b ... Light emitted from the organic light emitting layer, total reflection preventing surface-anode interface Light that goes out without being totally reflected 10 ... core material 10b ... resin 11 that forms the core material according to the present invention ... total reflection preventing surface 11b ... total reflection preventing surface is formed Resin 12 ... Shaping sheet 13a forming a total antireflection surface ... Substrate example 1 relating to the present invention
13b ... Example 2 of substrate related to the present invention
13c: Example of substrate 3 according to the present invention
14 ... T die 15 ... first clamping roll 16a ... second clamping roll (for shaping)
16b ... 2nd pinching roll (for flat)
17 ... 1st cooling roll 18 ... 2nd cooling roll 19 ... Light extraction film A
20 ... Light extraction film B

Claims (11)

A transparent substrate for an EL device in which an anode, a hole injection layer, a hole transport layer, an interlayer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode are sequentially laminated,
A transparent substrate for an EL element, wherein a total reflection preventing surface having a light extraction function is provided on the surface or inside by a multilayer extrusion method or a thermal lamination method.   The transparent substrate for an EL element according to claim 1, wherein the total antireflection surface is formed of a light scattering element made of scattering particles or a lens-like shape.   3. The transparent substrate for an EL element according to claim 1, wherein the surface on the anode side has a concavo-convex structure having a height of 100 to 800 nm and an aspect ratio in the range of 1 to 3. 4.   The transparent substrate for an EL element according to any one of claims 1 to 3, wherein the arithmetic average roughness Ra of the surface on the anode side is 2.5 nm or less.   The transparent substrate for an EL element according to any one of claims 1 to 4, wherein the total antireflection surface is provided on a surface of the transparent substrate for an EL element that does not contact the anode.   The transparent substrate for an EL element according to claim 1, wherein the total reflection preventing surface is provided on a surface of the transparent substrate for an EL element that is in contact with the anode.   The transparent substrate for an EL element according to any one of claims 1 to 4, wherein the total antireflection surface is provided on both surfaces of the transparent substrate for an EL element.   The light reflection function of the total reflection preventing surface having the light extraction function is expressed by the shape of the substrate, that is, the total reflection prevention surface has a lens shape. The transparent substrate for EL elements as described in any one.   Organic EL illumination using the transparent substrate for EL elements as described in any one of Claims 1-8.   An organic EL light source using the transparent substrate for an EL element according to any one of claims 1 to 8.   An organic EL display device using the organic EL light source according to claim 10.

Images