JP2016076301A - Light emitting element base material and manufacturing method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting element base material capable of efficiently extracting light output from a laminated light emitting element part.SOLUTION: A light emitting element base material includes a light transmitting base material 102 and a high refractive index layer 120 arranged on the light transmitting base material. In the light emitting element base material, ends of the high refractive index layer are projected, and a light emitting element part is arranged at a portion other than the projected ends in the high refractive index layer on the opposite side of the light transmitting base material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light-emitting element substrate and a manufacturing method, and more particularly to a light-emitting element substrate and a manufacturing method having a structure in which light from stacked light-emitting element portions is efficiently extracted.

  Conventionally, an organic electro-luminescence (OEL) element (also referred to as an organic light-emitting diode (OLED)) is known as a light-emitting element. A general organic EL element includes a light-transmitting base material such as a glass substrate, and a light-emitting layer (also referred to as a light-emitting element portion in this specification) laminated on the base material. A general organic EL device has a light extraction efficiency (also referred to as a light extraction efficiency in this specification) of only 20%, which is emitted from the light emitting layer, passes through the substrate, and is emitted into the air. Not too much. In view of this, in lighting devices, display devices, and the like using panel-shaped organic EL elements, an external film for light diffusion is attached to a translucent substrate in consideration of the mass productivity of the panel. Although it depends on the element structure of the panel, even when an external film is attached to the element, the light extraction efficiency is about 25%, and the light loss is large. The reason for this is the total reflection of light at the existing interface between the organic layer (light emitting layer) and the substrate. In particular, the influence of total reflection at the interface due to a difference in refractive index between a base material such as a glass substrate or a plastic substrate and a medium adjacent to the base material is large. Therefore, in order to further improve the light extraction efficiency, it is necessary to devise a structure inside the element.

  For example, it is known that a light scattering layer containing fine particles as a light scatterer is formed between a light emitting layer and a translucent substrate to form a light scattering portion (see, for example, Patent Document 1).

JP2009-4274 (paragraph 0035)

  However, in order to improve the light extraction efficiency in the light scattering portion containing fine particles, it is necessary to increase the amount of light scattering fine particles added in order to scatter light. As a result, the amount of light extracted increases, but the light absorption effect due to the addition of light-scattering fine particles is increased accordingly. Therefore, since light extraction and absorption occur at the same time, the light extraction effect is not sufficient.

  Moreover, the surface of the light-scattering part in which the light-scattering layer containing microparticles | fine-particles was uneven | corrugated with the particle | grains exposed to the surface of a light-scattering layer. Therefore, it has been proposed to form a buffer layer on the surface of the light scattering layer to improve smoothness and reduce the total reflection of light (see, for example, cited document 1).

  However, when a buffer layer is formed on the surface of the light scattering layer, if the surface of the buffer layer and the light emitting surface are completely smooth surfaces, there will be no problem in laminating them. It is difficult to make the surface completely smooth, and there is a problem that if there is even a small convex portion at one place, the light emitting layer is damaged from that point.

  This invention is made | formed in view of such a problem, The place made into the objective is to provide the light emitting element base material which can take out the light from the laminated | stacked light emitting element part efficiently. It is another object of the present invention to provide a light-emitting element substrate having a structure in which the light-emitting layer is hardly damaged even when there are irregularities such as foreign matters on the light-emitting surface.

  In order to achieve such an object, one embodiment of the present invention is a light-emitting element substrate. A light emitting element base material comprises a translucent base material and a high refractive index layer disposed on the translucent base material. The high refractive index layer has a raised end portion, and is for arranging the light emitting element portion in a portion other than the raised end portion on the opposite side of the translucent substrate.

  In one embodiment, the high refractive index layer has a refractive index of 1.7 or greater. The high refractive index layer may include light diffusing particles.

  In one embodiment, the high refractive index layer may have a refractive index of less than 1.7, and may have a prism shape in which a portion other than the raised end is inclined with respect to two axes.

  In one embodiment, a second high refractive index layer having a refractive index of 1.7 or more that does not include light diffusing particles may be laminated on the surface of the high refractive index layer.

  Another embodiment of the present invention is a method for producing a light-emitting element substrate. The manufacturing method of the light-emitting element substrate includes a step of pasting a masking film on a light-transmitting substrate, a step of peeling a part of the masking film, and a portion of the masking film of the light-transmitting substrate. A step of applying a high refractive index resin to a part including the periphery of the part and a part of the masking film which has been peeled off, a process of peeling off the remaining part of the masking film, and a masking film of the translucent substrate And a step of curing a resin having a high refractive index at a part where a part of the resin is peeled off.

  As described above, according to the present invention, light from the stacked light emitting element portions can be efficiently extracted, and the light emitting layer is not easily damaged even if there are irregularities such as foreign matters on the light emitting surface. A light emitting element substrate can be provided.

It is a figure which shows the light emitting element base material concerning one Embodiment of this invention, (a) is a top view, (b) is sectional drawing. It is a figure which shows the light emitting element base material concerning one Embodiment of this invention, (a) is a top view, (b) is sectional drawing. It is a figure which shows the light emitting element base material concerning one Embodiment of this invention, (a) is a top view, (b) is sectional drawing. It is a figure which shows the light emitting element base material concerning one Embodiment of this invention, (a) is a top view, (b) is sectional drawing, (c) is a perspective view of a high refractive part. It is a figure which shows the light emitting element base material concerning one Embodiment of this invention, (a) is a top view, (b) is sectional drawing, (c) is a perspective view of a high refractive part. It is a figure explaining the manufacturing method of the light emitting element base material concerning one Embodiment of this invention. It is a figure which shows the mode of permeation | transmission / reflection of the light in the light emitting element base material concerning one Embodiment of this invention. It is a figure which shows the mode of permeation | transmission / reflection of the light in the light emitting element base material concerning one Embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Specific compositions and numerical values in the following description are examples, and the present invention is not limited to these composition examples and numerical examples. It goes without saying that the present invention can be implemented with other compositions and numerical values without losing generality. The same or similar reference numerals in the drawings indicate the same or similar elements. Therefore, repeated description is omitted.

  Below, the light emitting element base material which concerns on this invention WHEREIN: The organic EL element comprised by arrange | positioning the light emitting element part comprised with an organic thin film, the electrode which supplies an electron and a hole to a light emitting element part, etc. is illustrated. In the organic EL element described here, light from the light emitting surface of the light emitting element portion is transmitted to the outside through the light emitting element base (translucent base).

  As described above, when light emitted from the light emitting element is emitted from the translucent substrate to the outside, total reflection occurs at the interface due to the difference in refractive index between the translucent substrate and air, and light is emitted to the outside. Is not produced, and light loss occurs. There is a method of reducing light loss by providing a light scattering element in the structure of the organic EL element so that light is not lost, thereby reducing total reflection. However, when many light scattering elements are added, the light extraction efficiency is improved by reducing the total reflection of light, and at the same time, the light absorption in the light scattering element and the light reflection elements in the light scattering element are increased. Since light absorption and light loss occur simultaneously, light cannot be extracted efficiently.

  The light totally reflected at the boundary surface of the medium repeats total reflection between the boundary surfaces and gradually moves to the edge of the medium. Therefore, light generated in any area of the light emitting surface is collected at the edge of the medium by repeating total reflection. Therefore, providing the scattering element at the end of the medium where the light repeats total reflection allows the light to be efficiently scattered, which is convenient.

  Therefore, in the present invention, the end of the medium between the light emitting element part and the translucent substrate is raised, and the reflection direction of the light gathered at the raised end by repeating total reflection is changed abruptly. The substrate can be transmitted and more light can be extracted.

(First embodiment)
1A and 1B are diagrams showing an organic EL element 100 using a light emitting element substrate according to a first embodiment of the present invention, where FIG. 1A is a plan view and FIG. 1B is a cross-sectional view. An organic EL element 100 shown in FIG. 1 includes a light emitting element substrate having a translucent substrate 102 and a high refractive index layer 120 formed on the translucent substrate. The organic EL element 100 includes a light emitting element substrate (102, 120), three transparent electrode portions 106, a light emitting element portion 104, an insulating layer 110, and an electrode portion 108.

  Two of the three transparent electrode portions 106 are formed at positions sandwiching the high refractive index layer 120 on the translucent substrate 102, and the remaining one is not in contact with the other two and has a high refractive index layer 120. It is formed so as to cover.

  The light emitting element portion 104 is disposed on the high refractive index layer 120 via the transparent electrode portion 106 such that the light emitting surface faces the surface of the translucent substrate 102.

  The electrode part 108 is formed at a position opposite to the light emitting surface of the light emitting element part 104 and the high refractive index layer 120 on the translucent substrate 102 so as to be in contact with the two transparent electrode parts 106. Has been. An insulating layer 110 is formed between the electrode portion 108 and the transparent electrode portion 106 formed so as to cover the high refractive index layer 120, and maintains an electrically insulating state. The electrode portion 108 is a cathode that supplies electrons to the light emitting element portion 104, and the transparent electrode portion 106 formed so as to cover the high refractive index layer 120 is an anode that supplies holes to the light emitting element portion 104. Thereby, the light emitting element part 104 light-emits from the surface at the side of a light emitting element base material (102,120).

  The high refractive index layer 120 is a medium having a refractive index of 1.7 or more, and has a structure in which an end portion (a periphery, an edge, or an outer periphery of the high refractive index layer) is raised. Therefore, the light totally reflected at the interface with the translucent substrate 102 is repeatedly totally reflected in the high refractive index layer 120 and gathers at the end, and the reflection direction can be changed at the end of the high refractive index layer 120. . Thereby, the light which permeate | transmits a translucent base material and radiates | emits outside increases (it becomes possible to take out more light). Since the raised end of the high refractive index layer acts as a spacer for the upper portion of the light emitting element portion, the pressure applied to the light emitting element portion from the upper portion can be reduced, and the light emitting layer can be formed even if there are irregularities such as foreign matter on the light emitting surface. It becomes hard to receive damage.

  The thickness of the portion where the light emitting element portion 104 is disposed in the high refractive index layer 120 is desirably smaller than 100 μm. This is because when the thickness is 100 μm or more, the amount of water contained in the material is too large (the amount of water that can be accepted as EL is 100 μm in terms of thickness), and the light transmittance becomes weaker.

  Further, the width and thickness of the raised end portion in the high refractive index layer 120 are preferably larger than the thickness of the portion where the light emitting element portion 104 is disposed, and are 0.5 μm or more and 3 mm or less. If the width and thickness of the end portion increase, light absorption increases, leading to light loss. Conversely, if the end portion is too small, the light scattering effect decreases and efficient light extraction cannot be performed. .

  In addition, the shape of the protruding end of the high refractive index layer 120 may be a shape in which light is easily scattered, and may be a convex and smooth curved surface (FIG. 1B), or a small protrusion may be formed. Even when there are a plurality of lenses (not shown), when a plurality of convex lenses are arranged, or even when a large spherical projection is used, the light can be extracted by the lens effect, and the shape is not specified.

  Most of the light can be extracted to the outside through the translucent substrate 102 by irregular reflection at the raised portion of the end portion of the high refractive index layer 120, but some light cannot be extracted. It becomes a loss.

  FIG. 7 is a view showing the behavior of light in the organic EL element 100 using the light emitting element base (102, 120) shown in FIG. The light totally reflected at the interface between the translucent substrate 102 and the air gathers at the raised end of the high refractive index layer 120 while repeating total reflection. The light incident on the raised end of the high refractive index layer 120 is reflected at the interface, and the direction of the light changes abruptly, and is transmitted through the light-transmitting substrate 102 to be emitted (taken out).

  In this embodiment, the amount of light extraction can be increased by using the high refractive index layer 124 including a few scattering elements that do not absorb light, instead of the high refractive index layer 120. .

  In the organic EL element 200 shown in FIG. 2, the light emitting element substrate includes a light transmissive substrate 102 and a high refractive index layer 124, and the high refractive index layer 124 includes light scattering particles 122 as scattering elements. Including. The light-scattering fine particles are not limited to this, for example, TiO2, SiO2, Al2O3, ZrO2, CaCO3, BaSO4, Mg3Si4O10 (OH) 2, etc., and various particle diameters of several tens nm to several hundreds μm, etc. Light scattering fine particles can be selectively used.

  When the light scattering particles 122 are included in the high refractive index layer 124, the thickness of the high refractive index layer 124 is preferably in the range of 0.005 to 100 μm. When the thickness of the high refractive index layer 124 is smaller than 0.005 μm, it is necessary to make the particle size of the scattering fine particles put into the high refractive index layer 124 smaller than the thickness, the particle size of the fine particles is too small, and the light scattering property is weakened. This is because it does not function as a scattering element. In addition, as described above with reference to FIG. 1, when the thickness of the high refractive index layer 124 is 100 μm or more, the amount of moisture contained in the material is excessive, and the light transmittance is further reduced.

  Further, similarly to the high refractive index layer 120 (FIG. 1), a raised portion is provided at the end of the high refractive index layer 124, and more light of scattering at the end can be extracted. The addition amount of the light scattering fine particles 122 is not so necessary. The amount added is preferably 40 w% or less. If it exceeds 40 w%, light will be absorbed by the light-scattering fine particles 122 and light will be reflected more than necessary. Note that fine particles such as ZrO 2 and TiO 2 having a particle size of nano-order and very weak functionality as a light scattering element are used as a refractive index control element for increasing the refractive index of the high refractive index layer 124, and light It may be distinguished from scattering fine particles.

  As with the high refractive index layer 120 (FIG. 1), the width and thickness of the raised end portion in the high refractive index layer 124 are larger than the thickness of the portion where the light emitting element portion 104 is disposed and are 0.5 μm or more and 3 mm or less. It is preferable. The shape of the raised end portion of the high refractive index layer 124 may be a shape in which light is easily scattered, similar to the shape of the raised end portion of the high refractive index layer 120.

  The surface of the high refractive index layer 124 is uneven due to the light scattering particles 122. Therefore, it is possible to improve the surface flatness by further laminating the high refractive index layer 120 that does not contain the light scattering particles.

  In the organic EL element 300 shown in FIG. 3, the light emitting element substrate includes a light transmissive substrate 102, a high refractive index layer 124, and a high refractive index layer 120, and light is applied to the surface of the high refractive index layer 124. A high refractive index layer 120 that does not contain scattering particles is laminated. As a measure of the surface flatness of the high refractive index layer 120, Ra is preferably 100 nm or less. If it exceeds that, leakage (leak light emission) is likely to occur in the light emitting element portion 104, and the reliability of the organic EL element is significantly lowered.

  In this embodiment, the amount of light extraction can be increased by using the high refractive index layer 124 including a few scattering elements that do not absorb light, instead of the high refractive index layer 120. .

  FIG. 8 is a diagram showing the behavior of light in the organic EL element 200 using the light emitting element substrate (102, 122) shown in FIG. If light scattering particles 124 do not exist from the light incident on the high refractive index layer 122 from the light emitting element portion 104, the light incident at an angle that totally reflects on the interface between the translucent substrate 102 and air is scattered by the light scattering particles 124. Then, the light passes through the translucent substrate 102 and is emitted (taken out) to the outside. On the other hand, of the light incident on the high refractive index layer 122 from the light emitting element portion 104, the light that does not hit the light scattering particles 124 or hits the light scattering particles 124 and scatters, and is totally reflected at the interface between the translucent substrate 102 and the air. Collect at the raised end of the high refractive index layer 122 while repeating total reflection. The light incident on the raised end of the high refractive index layer 122 is reflected at the interface, and the direction of the light changes abruptly, and is transmitted through the translucent substrate 102 to be emitted (extracted). The behavior of light in the organic EL element 300 using the light emitting element substrate (102, 122, 120) shown in FIG. 3 is also the same.

(Second Embodiment)
4A and 4B are views showing an organic EL element 400 using a light emitting element substrate according to a second embodiment of the present invention, in which FIG. 4A is a plan view and FIG. 4B is a cross-sectional view. In this embodiment, instead of the high refractive index layer 120 (FIG. 1), a prism-shaped high refractive index layer 126 inclined in two axes is used, so that the high refractive index layer 124 containing light-scattering fine particles ( It is possible to obtain the same performance as in FIG. The refractive index of the prism-shaped high refractive index layer 126 is preferably in the range of n <1.7. This is because if the refractive index exceeds 1.7, the light scattering property is lowered and the amount of light extracted is reduced.

  In FIG. 4B, the light behavior of the organic EL element 400 using the light emitting element base (102, 126) is also shown. Of the light incident on the prism-shaped high refractive index layer 126 from the light emitting element portion 104, if there is no prism shape, the light incident at the angle of total reflection at the interface between the translucent substrate 102 and air is the prism-shaped portion. Scattered, transmitted through the light-transmitting substrate 102, and emitted (taken out) to the outside. On the other hand, the light that does not scatter or scatters from the light emitting element portion 104 at the prism-shaped portion and is totally reflected at the interface between the light-transmitting substrate 102 and the air is raised in the high refractive index layer 126 while repeating total reflection. Gather to the edge. The light incident on the raised end of the prism-shaped high refractive index layer 126 is reflected by the interface, the direction of the light changes abruptly, passes through the translucent substrate 102, and is emitted to the outside (taken out). )

  As described above with reference to FIG. 3, light scattering particles are not included in the surface of the prism-shaped high refractive index layer 126 in order to improve the flatness of the surface of the prism-shaped high refractive index layer 126. A high refractive index layer may be laminated. In the organic EL element 500 shown in FIG. 5, a high refractive index layer 120 that does not contain light scattering particles is laminated on the surface of a prism-shaped high refractive index layer 126. As described above, Ra is preferably 100 nm or less as a measure of the surface flatness of the high refractive index layer 120 laminated. The behavior of light in the organic EL element 500 is the same as the behavior of light in the organic EL element 400.

(Third embodiment)
With reference to FIG. 6, the manufacturing method of the light emitting element base material concerning embodiment of this invention is demonstrated. The translucent substrate 102, the high refractive index layer 102, the high refractive index layer 124 containing light scattering particles, the prism-shaped high refractive index layer 126, the transparent electrode portion 106, and the like can be manufactured by roll-to-roll. Therefore, since it is possible to produce the organic material forming the light-emitting element part 104 in a roll-to-roll manner, a functional element part is produced on a conventional glass substrate, and a light scattering film is formed. Compared with the manufacturing process of molding on a plastic substrate, and then attaching a light-scattering film to the glass substrate through an adhesive, etc., the process is simplified, and the manufacturing lead time is increased, which is advantageous for cost reduction. There is a possibility.

  Referring to FIG. 6, first, a 30 μm-thick masking film 602 is bonded onto a 100 μm-thick PET (Polybutylene terephthalate) film 102, which is a translucent base material, and only the masking film is formed with a half-cut blade 604. After cutting (FIG. 6A), the masking film is peeled off (FIG. 6B), and the resin containing the light scattering fine particles 122 is gravure-coated (FIG. 6C). The resin is an ultraviolet (UV) reaction type resin, and the light scattering fine particles 122 are made of SiO 2 φ2.0 μm. The amount of light scattering fine particles added is 20% by weight. Next, unnecessary portions of the masking film are peeled off, and the resin is cured by irradiating UV (FIG. 6D). Through the steps of FIGS. 6A to 6D, a light emitting element substrate having the high refractive index layer 124 described with reference to FIG. 2 can be manufactured. In addition, in FIG. 6C, a light emitting element substrate having the high refractive index layer 120 described with reference to FIG. 1 can be manufactured by gravure coating a resin that does not include the light scattering fine particles 122. .

  In this manufacturing method, since the resin is also applied to the end portion of the half-cut masking film, the end portion can inevitably be raised when the masking film is peeled off. By adjusting the thickness of the masking film, the size of the raised portion can be adjusted.

  Further, even when a resin is laminated on the high refractive index layer 124 containing the light scattering fine particles 122, the steps of FIGS. 6 (e) to (h) similar to the steps of FIGS. 6 (a) to (d) are performed. It becomes possible to align and laminate. In the step of FIG. 6 (g), the resin that does not include the light-scattering particles is gravure-coated so that the light-transmitting substrate 102 and the light-transmitting substrate shown in FIG. A light emitting element substrate having the refractive index layer 124 and the high refractive index layer 120 can be manufactured.

  Note that the prism shape shown in FIGS. 4C and 5C can be obtained by embossing with a mold before the resin is irradiated with UV (for example, in the step of FIG. 6C or 6D). The high refractive index layer 126 can be formed. Similarly, a shape in which light is easily scattered can be formed by embossing the shape of the protruding end with a mold.

  In the present embodiment, the heat of the high refractive index layer 124 (scattering layer) including the light scattering particles 122 is 5 μm, and the thickness of the high refractive index layer 120 not including the light scattering particles laminated thereon is 10 μm. The resin was applied.

  ITO was used for the transparent electrode portion 106 to form a film by sputtering at 150 nm. In order to prevent moisture permeability, the surface opposite to the surface on which the high refractive index layer 120 of the PET film was formed was bonded to the glass surface using a transparent adhesive film. The configuration of the translucent substrate is an example, and the present invention is not limited to this. The refractive index of the high refractive index layer was 1.7.

  In the light emitting element portion 104, α-npd was deposited to 70 nm, Alq 3 to 60 nm, and Al to 100 nm on the ITO transparent electrode portion 106. Compared to a reference made simply on glass, an efficiency improvement of about 1.7 times was confirmed.

  As described above, according to the present invention, it is possible to provide a light emitting element substrate that can efficiently extract light from the stacked light emitting element portions. In addition, since the raised end of the high refractive index layer acts as a spacer, the pressure applied to the light emitting element part from the top can be reduced, so that the light emitting layer is not easily damaged even if there are irregularities such as foreign matter on the light emitting surface. It becomes possible to provide the light emitting element substrate.

100, 200, 300, 400, 500 Organic EL element 102 Translucent base material 104 Light emitting element part 106 Transparent electrode part 108 Electrode part (cathode)
110 Insulating Layer 120 High Refractive Index Layer 122 Light Scattering Particle 124 High Refractive Index Layer Containing Light Scattering Particle 126 Prism-shaped High Refractive Index Layer 602 Masking Film 604 Half Cut Blade

Claims (7)

A light-emitting element substrate,
A translucent substrate;
Comprising a high refractive index layer disposed on the translucent substrate,
The high refractive index layer has a raised end portion, and is a light emitting element base material for disposing a light emitting element portion in a portion other than the raised end portion on the opposite side of the translucent base material. .   The light-emitting element substrate according to claim 1, wherein the high refractive index layer has a refractive index of 1.7 or more.   The light-emitting element substrate according to claim 1, wherein the high refractive index layer contains light diffusing particles.   2. The light-emitting element substrate according to claim 1, wherein the high refractive index layer has a prism shape in which a portion other than the raised end is inclined in two axes.   The light-emitting element substrate according to claim 4, wherein the high refractive index layer has a refractive index of less than 1.7.   The light emitting element group according to claim 3, 4 or 5, wherein a second high refractive index layer having a refractive index of 1.7 or more not including light diffusing particles is laminated on the surface of the high refractive index layer. Wood. A method for manufacturing a light-emitting element substrate,
A step of pasting a masking film on a translucent substrate;
Peeling a part of the masking film;
A step of applying a resin having a high refractive index to a portion including a portion of the translucent base material from which the masking film is partially peeled and a portion of the masking film which is peeled off;
Peeling off the remaining portion of the masking film;
Curing the high-refractive index resin at a portion where a part of the masking film of the translucent substrate is peeled off.

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