WO2013175868A1

WO2013175868A1 - Surface-emitting element

Info

Publication number: WO2013175868A1
Application number: PCT/JP2013/060018
Authority: WO
Inventors: 孝二郎関根
Original assignee: コニカミノルタ株式会社
Priority date: 2012-05-24
Filing date: 2013-04-02
Publication date: 2013-11-28

Abstract

A surface-emitting element (4) is provided with: a light emitting layer (43), which generates light; a first electrode layer (42), which is provided on the light emitting layer (43) surface on one side of the light emitting layer, and which can pass through the light generated by the light emitting layer (43); a second electrode layer (44), which is provided on the light emitting layer (43) surface on the other side of the light emitting layer; a light passing layer (41), which is provided on the first electrode layer (42) surface on the reverse side of the surface where the light emitting layer (43) is positioned, and which can pass through the light generated by the light emitting layer (43); and a light extraction layer (46), which is provided on the light passing layer (41) surface on the reverse side of the surface where the first electrode layer (42) is positioned, and which improves efficiency of extraction of the light from the light passing layer (41). The side surface of the light passing layer (41) includes a tilted surface (45), which is tilted further outside than the side surface of the first electrode layer (42) from the first electrode layer (42) side toward the light extraction layer (46) side.

Description

Surface light emitting device

The present invention relates to the structure of a surface light emitting device.

As a new light source, a surface light emitting element can be mentioned. In the surface light emitting element, optimization of the structure of the surface light emitting element is being studied in order to improve the light extraction efficiency.

Japanese Unexamined Patent Application Publication No. 2010-123436 (Patent Document 1) discloses a surface light emitting device using organic EL (Electro-Luminescence). In this surface light emitting device, a microlens sheet is disposed on the light extraction surface side of the substrate in order to improve the light extraction efficiency.

Japanese Unexamined Patent Application Publication No. 2004-119211 (Patent Document 2) discloses a surface light emitting element using an organic EL as a backlight of a liquid crystal display device. In this surface light emitting device, in order to improve the light extraction efficiency, the side surface of the transparent substrate is inclined outward, and the light emitted from the light source is reflected to the liquid crystal panel side using the inclined side surface. Is adopted.

JP 2010-123436 A JP 2004-119211 A

In the future, since the demand for surface light emitting devices is expected to expand, it is important to develop a new surface light emitting device structure that can improve the light extraction efficiency of the surface light emitting device.

Therefore, an object of the present invention is to provide a surface light emitting device having a structure that can improve light extraction efficiency.

In the surface light emitting device according to the present invention, a light emitting layer that generates light, a first electrode layer that is provided on one surface of the light emitting layer and that allows light generated from the light emitting layer to pass through, The second electrode layer provided on the other surface of the light emitting layer, and the surface of the first electrode layer opposite to the surface on which the light emitting layer is located, pass light generated from the light emitting layer. A light passage layer that is possible, and a light extraction layer that is provided on the surface of the light passage layer opposite to the surface on which the first electrode layer is located and that increases the light extraction efficiency from the light passage layer. .

The side surface of the light passage layer includes an inclined surface that extends outward from the side surface of the first electrode layer as it goes from the first electrode layer side to the light extraction layer side.

According to the present invention, it is possible to provide a surface light emitting device having a structure capable of improving light extraction efficiency.

FIG. 3 is a cross-sectional view of the surface light-emitting element according to Related Technology 1 taken along line II in FIG. 2. It is a top view of the surface emitting element in the related art 1. FIG. 5 is a cross-sectional view of the surface light-emitting element according to Related Technology 2 taken along line III-III in FIG. 4. It is a top view of the surface emitting element in related technology 2. FIG. 7 is a cross-sectional view of the surface light emitting element according to Related Technology 3 as viewed in the direction of arrows VV in FIG. 6. It is a top view of the surface emitting element in the related technique 3. FIG. 9 is a cross-sectional view of the surface light emitting element according to the first embodiment, taken along line VII-VII in FIG. FIG. 3 is a plan view of the surface light emitting element in the first embodiment. FIG. 11 is a cross-sectional view taken along the line IX-IX of FIG. FIG. 6 is a plan view of a surface light emitting element in a second embodiment. FIG. 13 is a cross-sectional view taken along the line XI-XI in FIG. FIG. 6 is a plan view of a surface light emitting element in a third embodiment. FIG. 15 is a cross-sectional view taken along the line XIII-XIII in FIG. FIG. 10 is a plan view of a surface light emitting element in a fourth embodiment. FIG. 17 is a cross-sectional view taken along the line XV-XV in FIG. 16 of the surface light emitting element in the fifth embodiment. FIG. 10 is a plan view of a surface light emitting element in a fifth embodiment. FIG. 19 is a cross-sectional view of the surface light-emitting element according to the sixth embodiment, taken along line XVII-XVII in FIG. It is a top view of the surface emitting element in Embodiment 6. It is a figure which shows the light extraction efficiency of the surface emitting element in the related art 1-3 and Embodiment 1-6.

The surface light emitting device in each embodiment based on the present invention will be described below with reference to the drawings. Note that in the embodiments described below, when referring to the number, amount, and the like, the scope of the present invention is not necessarily limited to the number, amount, and the like unless otherwise specified. The same parts and corresponding parts are denoted by the same reference numerals, and redundant description may not be repeated. In addition, it is planned from the beginning to use the structures in the embodiments in appropriate combinations.

(Related technologies 1 to 3: surface light emitting devices 1 to 3)
With reference to FIGS. 1 to 6, the surface light emitting devices 1 to 3 in the related arts 1 to 3 will be described before the structure of the surface light emitting device in each embodiment based on the present invention is described.

(Surface emitting element 1)
First, with reference to FIG. 1 and FIG. 2, the surface emitting element 1 in the related technique 1 is demonstrated. FIG. 1 is a cross-sectional view of a surface light emitting device 1 according to Related Art 1, and is a cross-sectional view taken along the line II in FIG. FIG. 2 is a plan view of the surface light-emitting element 1 in the related art 1.

The surface light emitting element 1 has a rectangular shape in plan view. As an example, it is a regular square having a side of about 50 mm. The surface light emitting device 1 includes a light emitting layer 13 that generates light, and a first electrode layer that is provided on one surface (front surface) of the light emitting layer 13 and that allows light generated from the light emitting layer 13 to pass therethrough. A light transmissive electrode) 12 and a second electrode layer (back electrode) 14 provided on the other surface (back surface) of the light emitting layer 13.

On the surface of the first electrode layer 12 opposite to the surface on which the light-emitting layer 13 is located, a light-passing layer 11 capable of passing light generated from the light-emitting layer 13 is provided.

As the light emitting layer 13, for example, an organic EL light emitting layer is used, and the layer thickness is about several tens of nanometers. For the first electrode layer 12 (anode layer), for example, a transparent oxide semiconductor (IZO (mixture of indium oxide and zinc oxide), ITO (mixture of indium oxide and tin oxide) or the like) is used. The layer thickness is about several nanometers to several hundreds of nanometers. For example, a thin film metal electrode (Ag, Al, Au, Cu, etc.) is used for the second electrode layer 14 (cathode layer), and the layer thickness is about 100 nm to 200 nm.

When organic EL is used for the light emitting layer 13, when a negative potential is applied to the second electrode layer 14 and a positive potential is applied to the first electrode layer 12, free electrons generated in the second electrode layer 14 and the first electrode layer The holes generated in 12 are combined in the light emitting layer 13, and the organic matter in the light emitting layer 13 becomes excited and emits light when returning to the original stable state.

The light transmission layer 11 may be made of a material transparent to the emission wavelength in addition to a glass substrate, such as inorganic materials such as quartz and sapphire, acrylic, polycarbonate, PET (Polyethylene terephthalate), PEN (Polyethylene). An organic material such as naphthalate (polyethylene naphthalate) is used, and the layer thickness is about 0.7 mm.

Light is generated from the light emitting layer 13 by applying predetermined power to the light emitting layer 13 using the first electrode layer 12 and the second electrode layer 14. The light generated in the light emitting layer 13 passes through the first electrode layer 12 and the light passing layer 11 to the air on the surface (upper surface in the drawing) side of the light passing layer 11 opposite to the first electrode layer 12. Light is extracted.

In the structure of the surface light-emitting element 1, the light inside the light passage layer 11 is only part of the light inside the light passage layer 11 due to total reflection at the interface between the light passage layer 11 and air. It cannot be taken out.

In the structure of the surface light emitting element 1, about 40% of the light inside the light passage layer 11 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness is about 0.7 mm, the ratio (thickness ratio) obtained by dividing the thickness of the light transmission layer 11 by the length of one side of the light emitting area is 0. 7/50 = 0.014.

(Surface emitting element 2)
Next, with reference to FIG. 3 and FIG. 4, the surface emitting element 2 in the related art 2 will be described. FIG. 3 is a cross-sectional view of the surface light emitting element 2 in the related art 2, and is a cross-sectional view taken along line III-III in FIG. FIG. 4 is a plan view of the surface light emitting element 2 in the related art 2.

The surface light emitting element 2 has a rectangular shape in plan view. The surface light emitting device 1 includes a light emitting layer 23 that generates light, and a first electrode layer (provided on one surface (front surface) of the light emitting layer 23, through which light generated from the light emitting layer 23 can pass. A light transmissive electrode) 22 and a second electrode layer (back electrode) 24 provided on the other surface (back surface) of the light emitting layer 23.

A light passage layer 21 through which light generated from the light emitting layer 23 can pass is provided on the surface of the first electrode layer 22 opposite to the surface on which the light emitting layer 23 is located.

The side surface of the light passage layer 21 includes an inclined surface 25 that spreads outward from the side surface of the first electrode layer 22 from the first electrode layer 22 side toward the upper side in the drawing. The inclined surface 25 is subjected to a light reflection process. In the surface light emitting element 2, the inclination angle (α) of the inclined surface 25 is 45 degrees.

The materials used and the layer thicknesses of the light emitting layer 23, the first electrode layer 22, and the second electrode layer 24 are the same as those of the surface light emitting element 1. The material used for the light transmission layer 21 is the same as that of the surface light emitting element 1, and the layer thickness is about 5 mm.

The light emitting layer 23, the first electrode layer 22, and the second electrode layer 24 are regular squares having a side of about 50 mm. The light transmission layer 21 is a regular square having a side of about 60 mm on the surface opposite to the first electrode layer 22.

Light is generated from the light emitting layer 23 by applying predetermined power to the light emitting layer 23 using the first electrode layer 22 and the second electrode layer 24. The light generated in the light emitting layer 23 passes through the first electrode layer 22 and the light passage layer 21 to the air on the surface (upper surface in the drawing) side of the light passage layer 21 opposite to the first electrode layer 22. Light is extracted.

In the structure of the surface light emitting element 2, the light inside the light passage layer 21 is only part of the light inside the light passage layer 21 due to total reflection at the interface between the light passage layer 21 and air. It cannot be taken out. However, compared with the surface light emitting element 1 of the related art 1, the surface light emitting element 2 is provided with the inclined surface 25, so that the light extraction efficiency is improved.

In the structure of the surface light emitting element 2, about 65% of the light inside the light passage layer 21 was emitted to the air. Since the length of one side of the light emission area is about 50 mm and the thickness of the light passage layer 21 is about 5 mm, the ratio of the thickness of the light passage layer 21 divided by the length of one side of the light emission area (thickness ratio) Then, 5/50 = 0.1.

(Surface emitting element 3)
Next, with reference to FIG. 5 and FIG. 6, the surface light emitting element 3 in the related art 3 will be described. FIG. 5 is a cross-sectional view of the surface light emitting element 3 in the related art 3, and is a cross-sectional view taken along line VV in FIG. FIG. 6 is a plan view of the surface light emitting element 3 in the related art 3.

The surface light emitting element 3 has a rectangular shape in plan view. As an example, it is a regular square having a side of about 50 mm. The surface light-emitting element 3 includes a light-emitting layer 33 that generates light and a first electrode layer (provided on one surface (front surface) of the light-emitting layer 33, through which light generated from the light-emitting layer 33 can pass. A light-transmitting electrode) 32 and a second electrode layer (back electrode) 34 provided on the other surface (back surface) of the light-emitting layer 33.

On the surface of the first electrode layer 32 opposite to the surface on which the light-emitting layer 33 is located, a light-passing layer 31 through which light generated from the light-emitting layer 33 can pass is provided.

An uneven light extraction layer 36 is provided on the surface of the light passage layer 31 opposite to the surface on which the first electrode layer 32 is located in order to increase the light extraction efficiency from the light passage layer 31.

The materials and layer thicknesses of the light emitting layer 33, the first electrode layer 32, the second electrode layer 34, and the light passing layer 31 are the same as those of the surface light emitting element 1. The light extraction layer 36 is formed by processing the surface of the light passage layer 31 into a microlens array.

As this microlens array, hemispheres having a diameter of about 30 μm are two-dimensionally arranged on the surface (light emitting surface) side of the light passage layer 31.

Light is generated from the light emitting layer 33 by applying a predetermined power to the light emitting layer 33 using the first electrode layer 32 and the second electrode layer 34. The light generated in the light emitting layer 33 passes through the first electrode layer 32, the light passage layer 31, and the light extraction layer 36, and the surface of the light extraction layer 36 opposite to the light passage layer 31 (upper surface in the drawing). ) Light is taken out to the air on the side.

In the structure of the surface light emitting element 3, a microlens array is used for the light extraction layer 36. By installing the light extraction layer 36 that scatters light such as a microlens array, a part of the light that cannot be extracted by total reflection is emitted to the air.

Since the angle at which the light reflected by the light extraction layer 36 is also changed from the incident angle, the light passing through the light passing layer 31, the first electrode layer 32, the light emitting layer 33, and the second electrode layer 34, Light that is reflected again by the two-electrode layer 34 and returns to the light-passing layer 31 through the light-emitting layer 33 and the first electrode layer 32 has an opportunity to be taken out to the air again by the microlens array. Even if it is not extracted once, it will be emitted to the air side by repeating reflection several times.

As described above, the surface light emitting element 3 in the related technique 3 is provided with the light extraction layer 36 using the microlens array as compared with the surface light emitting element 1 in the related technique 1, and thus the light extraction efficiency is improved. Improvements are being made.

In the structure of the surface light emitting element 3, about 68% of the light inside the light passage layer 31 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passing layer 31 is about 0.7 mm, the ratio (thickness) obtained by dividing the thickness of the light passing layer 31 by the length of one side of the light emitting area. Ratio) is 0.7 / 50 = 0.014.

(Embodiments based on the present invention)
Hereinafter, the surface light emitting device in each embodiment based on the present invention will be described with reference to the drawings.

Embodiment 1 Surface Light Emitting Element 4
With reference to FIG. 7 and FIG. 8, the surface light-emitting element 4 in Embodiment 1 is demonstrated. FIG. 7 is a cross-sectional view of the surface light-emitting element 4 in the present embodiment, which is a cross-sectional view taken along line VII-VII in FIG. FIG. 8 is a plan view of the surface light-emitting element 4 in the present embodiment.

The surface light emitting element 4 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. The surface light emitting element 4 includes a light emitting layer 43 that generates light, and a first electrode layer (provided on one surface (front surface) of the light emitting layer 43, through which light generated from the light emitting layer 43 can pass. A light-transmitting electrode) 42 and a second electrode layer (back electrode) 44 provided on the other surface (back surface) of the light-emitting layer 43.

On the surface of the first electrode layer 42 opposite to the surface on which the light emitting layer 43 is located, a light passage layer 41 through which light generated from the light emitting layer 43 can pass is provided.

An uneven light extraction layer 46 is provided on the surface of the light passage layer 41 opposite to the surface on which the first electrode layer 42 is located in order to increase the light extraction efficiency from the light passage layer 31.

The materials and layer thicknesses of the light emitting layer 33, the first electrode layer 32, the second electrode layer 34, and the light passing layer 31 are the same as those of the surface light emitting element 1. The light extraction layer 36 can be obtained by processing the surface of the light passage layer 31 into a microlens array shape or separately providing a microlens array sheet.

As an example of processing the microlens array, a hemisphere having a diameter of about 30 μm is two-dimensionally arranged on the surface (light emitting surface) side of the light passage layer 31. The diameter is preferably 10 μm to 100 μm. If it is 10 μm or more, the diffraction effect and coloring hardly occur, and if it is 100 μm or less, the thickness can be reduced.

In order to increase the light extraction efficiency of the light passage layer 41, the side surface of the light passage layer 41 has an inclined surface 45 that spreads outward from the side surface of the first electrode layer 42 from the first electrode layer 42 side toward the upper side in the drawing. including. The inclined surface 45 is subjected to a light reflection process. In some cases, the light reflection process is not performed. In this surface light emitting element 4, the inclination angle (α) of the inclined surface 45 is 45 degrees.

For example, an organic EL light emitting layer is used for the light emitting layer 43, and the layer thickness is about several tens of nm. For the first electrode layer 42 (anode layer), for example, a transparent oxide semiconductor (ITO, IZO, etc.) is used, and the layer thickness is about several nm to several tens of nm. For the second electrode layer 44 (cathode layer), for example, a thin film metal electrode (Ag, Al, Au, Cu, etc.) is used, and the layer thickness is about 100 nm to 200 nm.

In addition, although the case where organic EL was used for the light emitting layer was demonstrated, if it is a light emitting layer which has equivalent performance, it will not be limited to organic EL, and the light emitting layer using inorganic EL, surface emitting laser, surface emitting LED, etc. Can also be adopted. The same applies to the following embodiments.

The light passing layer 41 may be a transparent material at the emission wavelength in addition to a glass substrate, such as inorganic materials such as quartz and sapphire, acrylic, polycarbonate, PET (Polyethylene terephthalate), PEN (Polyethylene naphthalate: An organic material such as polyethylene naphthalate) is used, and the layer thickness is about 5 mm.

The light emitting layer 43, the first electrode layer 42, and the second electrode layer 44 are regular squares having a side of about 50 mm. The light passage layer 41 is a regular square having a side of about 60 mm on the surface opposite to the first electrode layer 42.

Compared to the configuration of the surface light emitting element 2 of Related Technology 2, a light extraction layer 46 using a microlens array is provided. Compared to the configuration of the surface light emitting element 3 of Related Art 3, an inclined surface 45 is provided on the side surface of the light passage layer 41.

In the configuration of the surface light emitting element 2 of the related art 2, light is efficiently extracted to the air side by the inclined surface, but part of the light is reflected again by the inclined surface to the light passage layer and confined by total reflection. Exists.

In the configuration of the surface light emitting element 2 of the related art 2, since there is no light extraction layer, light once confined in the light passage layer is not emitted to the air even if there is an inclined surface. Therefore, in the configuration of the surface light emitting element 2 of the related art 2, there is a limit to improving the light extraction efficiency. In order to extract the light confined in the light passage layer, the light extraction efficiency can be further improved by providing a light extraction layer.

In the structure of the surface light emitting element 3 of Related Technology 3, light extraction is realized by multiple reflection in the vertical direction of the light extraction layer and the light emitting layer. However, light absorption by the second electrode layer (back electrode), the light emitting layer, and the first electrode layer 12 (transparent electrode) cannot be ignored, and there is a limit to improving light extraction.

By simply increasing the thickness of the light passage layer, the light that reaches the side surface of the light passage layer either returns into the light passage layer or exits from the side surface of the light passage layer. It is difficult to extract light on the side opposite to the electrode layer (upward).

By increasing the thickness of the light-passing layer and forming an inclined surface on the side surface, it is possible to efficiently extract light that has reached the side surface at a stage where the number of multiple reflections, which is a cause of light loss, is low, on the inclined surface. Therefore, the light extraction efficiency can be further improved as compared with the configuration of the surface light emitting element 3 of the related technique 3.

In the structure of the surface light emitting element 4, about 78% of the light inside the light passage layer 41 was emitted to the air. Since the length of one side of the light emission area is about 50 mm and the thickness of the light passage layer 41 is about 5 mm, the ratio of the thickness of the light passage layer 41 divided by the length of one side of the light emission area (thickness ratio) Then, 5/50 = 0.1.

As the thickness ratio of the light passage layer 41 is increased, the light extraction efficiency can be increased. However, in order to realize a thin surface light emitting element, it is necessary to have a finite thickness. The applicable range of the thickness ratio is preferably 0.05 to 0.5, and more preferably 0.05 to 0.1 from the viewpoint of thinness.

(Embodiment 2: Surface light emitting element 5)
With reference to FIG. 9 and FIG. 10, the surface emitting element 5 in Embodiment 2 is demonstrated. FIG. 9 is a cross-sectional view of the surface light-emitting element 5 in the present embodiment, and is a cross-sectional view taken along line IX-IX in FIG. FIG. 10 is a plan view of the surface light-emitting element 5 in the present embodiment.

The surface light emitting element 5 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. The surface light-emitting element 5 includes a light-emitting layer 53 that generates light, and a first electrode layer that is provided on one surface (front surface) of the light-emitting layer 53 and that allows light generated from the light-emitting layer 53 to pass therethrough. A light-transmitting electrode) 52 and a second electrode layer (back electrode) 54 provided on the other surface (back surface) of the light-emitting layer 53.

A light passage layer 51 through which light generated from the light emitting layer 53 can pass is provided on the surface of the first electrode layer 52 opposite to the surface on which the light emitting layer 53 is located.

In order to increase the light extraction efficiency of the light passage layer 51, the side surface of the light passage layer 51 has an inclined surface 55 that spreads outward from the side surface of the first electrode layer 52 from the first electrode layer 52 side toward the upper side in the drawing. including. The inclined surface 55 is subjected to a light reflection process. In some cases, the light reflection process is not performed. In the surface light emitting element 5, the inclination angle (α) of the inclined surface 55 is 45 degrees.

The materials and layer thicknesses of the light emitting layer 53, the first electrode layer 52, the second electrode layer 54, and the light passage layer 51 are the same as those of the surface light emitting element 4.

The light emitting layer 53, the first electrode layer 52, and the second electrode layer 54 are regular squares having a side of about 50 mm. The light transmission layer 51 is a regular square having a side of about 60 mm on the surface opposite to the first electrode layer 52.

An uneven light extraction layer 56 is provided on the surface of the light passage layer 51 opposite to the surface on which the first electrode layer 52 is located. For the light extraction layer 56, a microlens array similar to that of the surface light emitting element 4 is used.

When the configuration of the surface light emitting element 4 and the configuration of the surface light emitting element 5 in the present embodiment are compared, the region where the light extraction layer 56 is provided is different. In the surface light emitting element 5 in the present embodiment, the light extraction layer 56 is provided at a position covering the light emitting layer 53, and the light extraction layer 56 is not provided at a position where the inclined surface 55 faces.

Thus, by limiting the region where the light extraction layer 56 is provided, light extraction in the region facing the light emitting layer 53 is performed in the light extraction layer 56. Since most of the light reflected on the inclined surface 55 travels in the direction perpendicular to the light passage layer 51, it is more preferable not to install the light extraction layer 56 having a light scattering effect at the position where the inclined surface 55 faces. An improvement in light extraction efficiency can be expected.

In the structure of the surface light emitting element 5, about 84% of the light inside the light passage layer 51 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passing layer 51 is about 5 mm, the ratio of the thickness of the light passing layer 51 divided by the length of one side of the light emitting area (thickness ratio) Then, 5/50 = 0.1.

In the present embodiment, the exposed region of the light passage layer 51 is provided so as to surround the light extraction layer 56, but the embodiment is not limited thereto. As long as the light extraction layer 56 covers the light emitting layer 53, the exposed region of the light passage layer 51 may be in any form. For example, in FIG. 10, the exposed region of the light passage layer 51 may be provided only on the left and right sides of the light extraction layer 56, and the light extraction layer 56 may be provided so as to cover the light passage layer 51 in the upper and lower sides. The same applies to the following embodiments.

(Embodiment 3: Surface light emitting element 6)
With reference to FIG. 11 and FIG. 12, the surface emitting element 6 in Embodiment 3 is demonstrated. FIG. 11 is a cross-sectional view of the surface light emitting element 6 in the present embodiment, and is a cross-sectional view taken along line XI-XI in FIG. FIG. 12 is a plan view of the surface light-emitting element 6 in the present embodiment.

The surface light emitting element 6 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. The surface light-emitting element 6 includes a light-emitting layer 63 that generates light, and a first electrode layer (provided on one surface (surface) of the light-emitting layer 63, through which light generated from the light-emitting layer 63 can pass. A light transmissive electrode) 62 and a second electrode layer (back electrode) 64 provided on the other surface (back surface) of the light emitting layer 63.

On the surface of the first electrode layer 62 opposite to the surface on which the light emitting layer 63 is located, a light passing layer 61 capable of passing light generated from the light emitting layer 63 is provided.

In order to increase the light extraction efficiency of the light passage layer 61, the side surface of the light passage layer 61 has an inclined surface 65 that spreads outward from the side surface of the first electrode layer 62 from the first electrode layer 62 side toward the upper side in the drawing. including. The inclined surface 65 is subjected to a light reflection process. In some cases, the light reflection process is not performed. In the surface light emitting element 6, the inclination angle (α) of the inclined surface 45 is 45 degrees.

The materials and layer thicknesses of the light emitting layer 63, the first electrode layer 62, the second electrode layer 64, and the light passage layer 61 are the same as those of the surface light emitting element 4.

The light emitting layer 63, the first electrode layer 62, and the second electrode layer 64 are regular squares having a side of about 50 mm. The light transmission layer 61 is a regular square having a side of about 60 mm on the surface opposite to the first electrode layer 62.

A light extraction layer 66 is provided on the entire surface of the light passage layer 61 opposite to the surface on which the first electrode layer 62 is located. Specifically, a fine particle dispersion type diffusion layer is used for the light extraction layer 66. For this diffusion layer, for example, a diffusion film “Light Up (registered trademark) 100NSH” manufactured by Kimoto Co., Ltd. was used. This “Light-Up (registered trademark) 100NSH” has a configuration in which a diffusion layer in which diffusion beads are dispersed is laminated on a 100 μm PET base material.

Even when a diffusion layer is used for the light extraction layer 66, the same effect as that of the surface light-emitting element 4 in the first embodiment can be obtained. About 76% of the internal light was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passing layer 61 is about 5 mm, the ratio of the thickness of the light passing layer 41 divided by the length of one side of the light emitting area (thickness ratio) Then, 5/50 = 0.1.

(Embodiment 4: Surface light emitting element 7)
With reference to FIG. 13 and FIG. 14, the surface light emitting element 7 in the fourth embodiment will be described. FIG. 13 is a cross-sectional view of the surface light emitting device 7 in the present embodiment, and is a cross-sectional view taken along line XIII-XIII in FIG. FIG. 14 is a plan view of the surface light-emitting element 7 in the present embodiment.

The surface light emitting element 7 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. This surface light emitting element 7 is provided with a light emitting layer 73 that generates light and a first electrode layer (provided on one surface (front surface) of the light emitting layer 73, through which light generated from the light emitting layer 73 can pass. A light transmissive electrode) 72 and a second electrode layer (back surface electrode) 74 provided on the other side surface (back surface) of the light emitting layer 73.

On the surface of the first electrode layer 72 opposite to the surface on which the light emitting layer 73 is located, a light passing layer 71 capable of passing light generated from the light emitting layer 73 is provided.

In order to increase the light extraction efficiency of the light passage layer 71, the side surface of the light passage layer 71 has an inclined surface 75 that spreads outward from the side surface of the first electrode layer 72 from the first electrode layer 72 side toward the upper side in the drawing. including. The inclined surface 75 is subjected to light reflection processing. In some cases, the light reflection process is not performed. In the surface light emitting element 7, the inclined angle (α) of the inclined surface 75 is 45 degrees.

The materials used and the layer thicknesses of the light emitting layer 73, the first electrode layer 72, the second electrode layer 74, and the light passage layer 71 are the same as those of the surface light emitting element 4.

The light emitting layer 73, the first electrode layer 72, and the second electrode layer 74 are regular squares having a side of about 50 mm. The light passage layer 71 is a regular square having a side of about 60 mm on the surface opposite to the first electrode layer 72.

A light extraction layer 76 is provided on the surface of the light passage layer 71 opposite to the surface on which the first electrode layer 72 is located. For the light extraction layer 76, a fine particle dispersion type diffusion layer similar to the surface light emitting element 6 is used.

When the structure of the surface light emitting element 6 is compared with the structure of the surface light emitting element 7 in the present embodiment, the region where the light extraction layer 76 is provided is different. In the surface light emitting element 7 in the present embodiment, the light extraction layer 76 is provided at a position covering the light emitting layer 73, and the light extraction layer 76 is not provided at a position where the inclined surface 75 faces.

Thus, by limiting the region where the light extraction layer 76 is provided, the light extraction in the region facing the light emitting layer 73 is performed by the light extraction layer 76. Since most of the light reflected on the inclined surface 75 travels in a direction perpendicular to the light passage layer 71, it is expected that the light extraction efficiency will be further improved if the light extraction layer 76 having a light scattering effect is not provided. it can.

In the structure of the surface light emitting element 7, about 82% of the light inside the light passage layer 71 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passing layer 51 is about 5 mm, the ratio of the thickness of the light passing layer 71 divided by the length of one side of the light emitting area (thickness ratio) Then, 5/50 = 0.1.

(Embodiment 5: Surface light emitting element 8)
With reference to FIG. 15 and FIG. 16, the surface light-emitting element 8 in Embodiment 5 is demonstrated. FIG. 15 is a cross-sectional view of the surface light-emitting element 8 in the present embodiment, and is a cross-sectional view taken along line XV-XV in FIG. FIG. 16 is a plan view of the surface light-emitting element 8 in the present embodiment.

The surface light emitting element 8 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. The surface light-emitting element 8 includes a light-emitting layer 83 that generates light, and a first electrode layer (provided on one surface (front surface) of the light-emitting layer 83, through which light generated from the light-emitting layer 83 can pass. A light transmissive electrode) 82 and a second electrode layer (back electrode) 84 provided on the other surface (back surface) of the light emitting layer 83.

On the surface of the first electrode layer 82 opposite to the surface on which the light emitting layer 83 is located, a light passing layer 81 capable of passing light generated from the light emitting layer 83 is provided. The surface of the light passage layer 81 on the first electrode layer 82 side is provided so as to protrude outward more than the side surface of the first electrode layer 82.

In order to increase the light extraction efficiency of the light passage layer 81, the side surface of the light passage layer 81 has an inclined surface 85 that spreads outward from the side surface of the first electrode layer 82 from the first electrode layer 82 side toward the upper side in the drawing. including. A light reflection process is performed on the surface that protrudes more outward than the side surfaces of the inclined surface 85 and the first electrode layer 82. In some cases, the light reflection process is not performed. In this surface light emitting element 8, the inclination angle (α) of the inclined surface 85 is 45 degrees.

The materials and layer thicknesses of the light emitting layer 83, the first electrode layer 82, the second electrode layer 84, and the light passage layer 81 are the same as those of the surface light emitting element 4.

The light emitting layer 83, the first electrode layer 82, and the second electrode layer 84 are regular squares having a side of about 50 mm. The surface of the light passing layer 81 on the first electrode layer 82 side is a regular square having a side of about 56 mm. The surface of the light transmission layer 81 opposite to the first electrode layer 82 side is a regular square having a side of about 66 mm.

An uneven light extraction layer 86 is provided on the surface of the light passage layer 81 opposite to the surface on which the first electrode layer 82 is located. For the light extraction layer 86, a microlens array similar to the surface light emitting elements 4 and 5 is used.

When the configuration of the surface light emitting element 5 is compared with the configuration of the surface light emitting element 8 in the present embodiment, the surface of the light passing layer 81 on the first electrode layer 82 side is outside the side surface of the first electrode layer 82. It is in the point which is provided so that it may protrude greatly toward. Even in the protruding portion, it is possible to expect an improvement in light extraction efficiency due to the light reflection effect.

In the structure of the surface light emitting element 8, about 82% of the light inside the light passage layer 81 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passing layer 51 is about 5 mm, the ratio of the thickness of the light passing layer 81 divided by the length of one side of the light emitting area (thickness ratio) Then, 5/50 = 0.1.

(Embodiment 6: Surface light emitting element 9)
With reference to FIG. 17 and FIG. 18, the surface light emitting element 9 in the sixth embodiment will be described. FIG. 17 is a cross-sectional view of the surface light emitting device 9 in the present embodiment, and is a cross-sectional view taken along line XVII-XVII in FIG. FIG. 18 is a plan view of the surface light emitting element 9 in the present embodiment.

The surface light emitting element 9 has a rectangular shape in plan view. The planar shape is not limited to a rectangular shape. The surface light-emitting element 9 includes a light-emitting layer 93 that generates light, and a first electrode layer (provided on one surface (front surface) of the light-emitting layer 93, through which light generated from the light-emitting layer 93 can pass. A light-transmitting electrode) 92 and a second electrode layer (back electrode) 94 provided on the other surface (back surface) of the light emitting layer 93.

A first light passage layer 91 and a second light passage layer 91a through which light generated from the light emitting layer 83 can pass are provided on the surface of the first electrode layer 92 opposite to the surface on which the light emitting layer 93 is located. It has been. The second light passage layer 91a located on the first electrode layer 92 side is provided so as to protrude largely outward from the side surface of the first electrode layer 82. The surface of the first light passage layer 91 on the second light passage layer 91 a side has the same shape as the first electrode layer 92.

In order to increase the light extraction efficiency of the first light passage layer 91, the side surface of the first light passage layer 91 is more outward than the side surface of the first electrode layer 92 from the first electrode layer 92 side toward the upper side in the drawing. An expanding inclined surface 95 is included. A light reflection process is performed on the inclined surface 95 and the surface that protrudes more outward than the side surface of the first electrode layer 92. In some cases, the light reflection process is not performed. In the surface light emitting element 9, the inclination angle (α) of the inclined surface 95 is 45 degrees.

The materials used and the layer thicknesses of the light emitting layer 93, the first electrode layer 92, and the second electrode layer 94 are the same as those of the surface light emitting element 4. Materials used for the first light passage layer 91 and the second light passage layer 91a are the same as those of the surface light emitting element 4. The layer thickness of the first light passage layer 91 is about 5 mm, and the layer thickness of the second light passage layer 91a is about 0.7 mm.

The light emitting layer 93, the first electrode layer 92, and the second electrode layer 94 are regular squares having a side of about 50 mm. The surface of the first light passage layer 91 on the first electrode layer 92 side is a regular square having a side of about 50 mm. The surface of the first light passage layer 91 opposite to the first electrode layer 92 side is a regular square having a side of about 60 mm.

An uneven light extraction layer 96 is provided on the surface of the first light passage layer 91 opposite to the surface on which the first electrode layer 92 is located. For the light extraction layer 96, the same microlens array as that of the surface light emitting elements 4 and 5 is used.

Further, in the surface light emitting element 9 of the present embodiment, the light extraction layer 96 is provided at a position covering the light emitting layer 93 in the same manner as the structure of the surface light emitting element 5 of the second embodiment.

In the present embodiment, the light passage layer has a two-layer structure of a first light passage layer 91 and a second light passage layer 91a. Even when the layer thickness of the light passage layer (first light passage layer 91) when forming the surface light emitting device is thin, the light passage layer (second light passage layer 91a) optically adhered as a separate member is used. It is possible to increase the effective layer thickness of the light passage layer.

Further, even when the first light passage layer 91 and the second light passage layer 91a have an area larger than the light emission area of the light emitting layer 93, the surface of the first light passage layer 91 on the first electrode layer 92 side has a light emission area. Accordingly, by providing an inclined surface in a portion larger than the area of the light emitting portion, a thin commonly used substrate (second light passage layer 91a) advantageous in terms of manufacturing and cost, and a thickness for light extraction are provided. It becomes possible to combine with the board | substrate (1st light passage layer 91) which has a slope.

In the structure of the surface light emitting element 9, about 83% of the light inside the light passage layer 81 was emitted to the air. Since the length of one side of the light emitting area is about 50 mm and the thickness of the light passage layer 51 is about 5 mm, the thickness of the light passage layer (the first light passage layer 91 + the second light passage layer 91a) is set to the light emission area. The ratio (thickness ratio) divided by the length of one side is 5.7 / 50 = 0.114.

FIG. 19 shows a list of light extraction efficiencies of the surface emitting element 1-9 in the related art 1-3 and the embodiment 1-6. The light extraction efficiency of the surface light emitting element 1-3 in Related Art 1-3 is in the range of 40% to 60%, but the light extraction efficiency of the surface light emitting element 4-9 in Embodiment 1-6 is 70%. It has improved from 80 to 80%.

The surface light emitting device in each embodiment of the present invention has been described above. However, the embodiment disclosed this time should be considered as illustrative in all points and not restrictive. Therefore, the scope of the present invention is defined by the terms of the claims, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

1,2,3,4,5,6,7,8,9 surface light emitting element, 11,21,31,41,51,61,71,81 light passing layer, 12,22,32,42,52, 62, 72, 82, 92 1st electrode layer, 13, 23, 33, 43, 53, 63, 73, 83, 93 Light emitting layer, 14, 24, 34, 44, 54, 64, 74, 84, 94th 2 electrode layer, 25, 45, 55, 65, 75, 85, 95 inclined surface, 36, 46, 56, 66, 76, 86, 96 light extraction layer, 91 first light passage layer, 91a second light passage layer .

Claims

A light emitting layer for generating light;
A first electrode layer provided on one surface of the light emitting layer and capable of passing light generated from the light emitting layer;
A second electrode layer provided on the other surface of the light emitting layer;
A light-passing layer provided on the surface of the first electrode layer opposite to the surface on which the light-emitting layer is located, and capable of passing light generated from the light-emitting layer;
A light extraction layer provided on a surface opposite to the surface on which the first electrode layer of the light passage layer is located, and increasing the light extraction efficiency from the light passage layer,
The side surface of the said light passage layer is a surface emitting element containing the inclined surface which spreads outside the side surface of the said 1st electrode layer as it goes to the said light extraction layer side from the said 1st electrode layer side.
The surface light emitting device according to claim 1, wherein when the light emitting layer is viewed from the light extraction layer side, the light extraction layer is provided at a position covering at least the light emission layer.
The surface light emitting device according to claim 2, wherein the light extraction layer is not provided at a position where the inclined surface faces when the light emitting layer is viewed from the light extraction layer side.
4. The surface light emitting device according to claim 1, wherein the inclined surface is subjected to a light reflection process.
The surface light emitting device according to any one of claims 1 to 4, wherein a surface of the light extraction layer opposite to a surface on which the light passage layer is located has an uneven shape.
The surface light emitting device according to any one of claims 1 to 4, wherein the light extraction layer is a light diffusion layer.