JP2001135477A - Organic el display element - Google Patents

Abstract

PROBLEM TO BE SOLVED: To increase light-producing efficiency of an organic EL display element used for various displays. SOLUTION: This organic EL display element has such a structure in which on a transparent plate 11, a transparent electrode 12, light-emitting color material 13, metal electrode 14 and an insulation plate 15 are laminated in order, the transparent electrode 12 and the metal electrode 14 constitute an anode and a cathode respectively, and one side of the transparent plate 11 not contacting with the transparent electrode 12 has a shape of a convex lens. By using a convex lens, light-producing efficiency can be improved, and a bright display element can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-efficiency light-emitting structure of an organic EL display device.

[0002]

2. Description of the Related Art In a conventional organic EL display device, as shown in FIG. 12, a transparent and flat glass plate 71, a transparent electrode 62 represented by ITO, a luminescent color material 63 (a hole injection material 71, a hole transport material). 72, luminescent material 73, electron transport material 74), metal electrode 6
4. In the configuration in which the insulating plates 65 are sequentially laminated, when a voltage is applied with the metal electrode 64 serving as a cathode and the transparent electrode 62 serving as an anode, light is excited by the luminescent material 73 in the luminescent color material 63, and the light is converted into flat glass. It reaches the outside through the plate 71.

[0003]

However, as shown in FIG. 13, when light is emitted to the outside through glass,
Since the refractive index of air is smaller than that of glass, light emitted at an angle larger than the critical angle θ is totally reflected. FIG. 13 is a cross-sectional view of a portion of the glass plate 71 of FIG. 12, and light from the light emitting material 73 passes from bottom to top in FIG. Since the refractive index of a generally used glass plate is about 1.5, the critical angle at which light exits from the glass to the air is 41.8 degrees as shown by the following equation 1.

[0004]

(Equation 1)

[0005] Therefore, the theoretical extraction efficiency is about 25.4% according to the following equation, and a considerable amount of light is wasted.

[0006]

(Equation 2)

An object of the present invention is to increase the light extraction efficiency in such an organic EL display device.

[0008]

SUMMARY OF THE INVENTION In order to solve this problem, the present invention is to minimize the probability that the emission angle becomes larger than the critical angle when light is emitted from the glass plate into the air. Specifically, one or both surfaces of the glass plate are formed into a convex lens shape, and at the same time, the metal electrode is correspondingly made into a concave mirror state when viewed from the light emitting side.

As a result, the probability that the angle of emission from the glass, which is a transparent plate, to the observation side, which is an air medium, becomes smaller than the above critical angle increases, the light extraction efficiency is improved, and a bright display element is obtained.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION
A transparent plate, a transparent electrode sequentially laminated on the transparent plate,
An organic E having a luminescent colorant and a metal electrode, wherein the surface of the transparent plate on the side not in contact with the transparent electrode has a single convex lens shape;
This is an L display element, and has an effect that light extraction efficiency is improved by using a convex lens, and a bright display element can be obtained.

According to a second aspect of the present invention, there is provided a transparent plate, a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate, and both surfaces of the transparent plate are formed as a single convex lens. An organic EL display element having a function of using a convex lens and converging light with a concave mirror to improve light extraction efficiency and obtain a bright display element.

According to a third aspect of the present invention, a transparent plate, a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate, wherein a surface of the transparent plate that is in contact with the transparent electrode are provided. A predetermined number of micro-convex lens-shaped organic EL display elements, and the metal electrodes corresponding to the micro-convex lenses each serve as a large number of micro-concave mirrors, and converge light so that the probability of emitting light at a critical angle or more is reduced. Light extraction efficiency is improved, and a bright display element can be obtained.

According to a fourth aspect of the present invention, there is provided a transparent plate, a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate, wherein the transparent plate is not in contact with the transparent electrode. The surface on the side is a single convex lens shape, the surface of the transparent plate in contact with the transparent electrode is an organic EL display element having a predetermined number of minute convex lens shapes, and a large number of minute concave mirrors focus light, and By passing the light through the convex lens, the light extraction efficiency is improved, and a bright display element can be obtained.

According to a fifth aspect of the present invention, there is provided a transparent plate, a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate, wherein both surfaces of the transparent plate have a predetermined number. An organic EL display element having the shape of a micro-convex lens, a large number of micro-concave mirrors converge light, and the light extraction efficiency is improved by passing through a micro-convex lens corresponding to the micro-concave mirror on a one-to-one basis. It has the effect that it can be obtained.

According to a sixth aspect of the present invention, there is provided a transparent plate, a transparent electrode, a luminescent colorant, and a metal electrode sequentially laminated on the transparent plate, wherein the transparent electrode is not in contact with the transparent electrode. This is an organic EL display element whose side surface is in the form of a predetermined number of minute convex lenses, and has the effect of improving the light extraction efficiency by passing through a large number of minute convex lenses and providing a bright display element.

According to a seventh aspect of the present invention, there is provided the organic EL display device according to any one of the third to sixth aspects, wherein the micro convex lens is formed for each pixel of the matrix type display, and the concave mirror corresponding to each pixel. Has a function of converging light and passing through a convex lens corresponding to a pixel one-to-one, thereby improving light extraction efficiency and obtaining a bright display element.

According to an eighth aspect of the present invention, the micro convex lens is formed for each picture element having one pixel unit including red, green and blue of a matrix type display. An organic EL display element, in which concave mirrors corresponding to the respective picture elements focus light and pass through a convex lens corresponding to the picture elements on a one-to-one basis, so that light extraction efficiency is improved and a bright display element can be obtained. It has the action of:

According to a ninth aspect of the present invention, there is provided the organic EL display element according to any one of the first to eighth aspects, wherein an insulating plate is provided on the metal electrode. It has the action of:

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a cross-sectional view of an organic EL device having improved light emission extraction efficiency. In FIG. 1, reference numeral 11 denotes a transparent plate, which is a single-sided convex lens mainly made of transparent glass or a transparent resin plate. Reference numeral 12 denotes a transparent electrode, which mainly uses ITO as a transparent conductive material. Reference numeral 13 denotes a luminescent color material, which is a general term for a material that controls a luminescent mechanism. 14 is a metal electrode, which is made of aluminum, lithium-
A metal having a work function of about 5 such as magnesium is used. Reference numeral 15 denotes an insulating plate, which electrically separates the metal electrode 14 from other substances and protects the laminated film. The insulating plate 15 may be a glass plate or an insulating thin film. In the case of an insulating thin film, a circuit board may be added to the surface opposite to the metal electrode 14. As a method for forming a display element, a transparent plate 11 is used as a substrate, and a thin film-shaped transparent electrode 12
After sequentially laminating the respective films of the luminescent color material 13 and the metal electrode 14, the insulating plate 15 is laminated. In some cases, the insulating plate 15 may be omitted.

Another method is to form a thin film of a metal electrode 14, a luminescent color material 13, and a transparent electrode 12 in order using an insulating plate 15 as a substrate.
1 is laminated.

As shown in FIG. 2, the transparent plate 11 is obtained by cutting out a square inscribed in a circle of a single-sided convex lens. FIG. 2A is a view of the single-sided lens viewed from above, and FIG. 2B is a cross-sectional view taken along the line AA ′. Although FIG. 2 shows a cutout square, it may be a rectangle.

The difference between the conventional organic EL element and this embodiment is that the transparent plate 11 is a parallel plate or a single-sided convex lens. FIG. 3 shows a sectional view of a surface portion of a transparent plate together with a conventional example. FIG. 3A is a cross-sectional view of a conventional device, and FIG. 3B is a cross-sectional view of the present embodiment. The light emitted from the luminescent material of the luminescent color material 13 passes through the hole transport material in the luminescent color material 13 and the transparent electrode 12 and reaches the transparent plate 11. In the figure, light is transmitted from bottom to top. The hole transport material and the layer of the transparent electrode 12 each have a thickness of 50 to 100 nm. When ITO is used for the transparent electrode 12, the refractive index of the ITO is about 1.8, and the refractive index when the transparent plate 11 is made of glass Since the rate is about 1.5,
It is considered that light from the light emitting material travels substantially straight to the transparent plate 11.

Therefore, as shown in FIG. 3 (a), the light incident at the critical angle θ cannot be emitted to the observation side opposite to the lamination surface, but has a one-side convex lens shape as shown in FIG. 3 (b). In this case, the critical angle θ is used to set the tangent g of the emission point P as the reference line.
Can also be emitted through the transparent plate 11 to the observation side, and can be sensed as light. That is, the light extraction efficiency can be improved, and a brighter display can be performed than the conventional one.

(Embodiment 2) Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.

FIG. 4 shows the organic E according to the second embodiment.
1 shows a cross-sectional view of an L element. In FIG. 4, 21 is a transparent plate, 2
2 is a transparent electrode, 23 is a luminescent colorant, 24 is a metal electrode, 25
Are insulating plates, which are the same as those described with reference to FIG. 1 as the first embodiment.

The difference from the first embodiment is that the transparent plate 21
Is a double-sided convex lens, and accordingly the transparent electrode 22,
The luminescent color material 23, the metal electrode 24, and the insulating plate 25 are concave when viewed from the observation side, so that the portion of the metal electrode 24 where the electrode is formed becomes a concave mirror. FIG. 3C is a sectional view of a surface portion of the transparent plate of the organic EL device according to the present embodiment. As described in the first embodiment, the light emitted at the critical angle θ can pass through the transparent plate 21 at the point P, be emitted to the observation side, and be sensed as light. Further, since the metal electrode forms a concave mirror, the light is not diverged, but is condensed, and becomes brighter than a flat surface. For the above reasons, the light extraction efficiency can be increased as compared with the conventional example, and a bright display can be performed.

(Embodiment 3) Hereinafter, a third embodiment of the present invention will be described with reference to the drawings.

FIGS. 5A and 5B are conceptual views of the organic EL device according to the present embodiment, wherein FIG. 5A is a plan view and FIG. 5B is a sectional view. As shown in FIG. 5, used for image display and the like,
This is a matrix-type display element that displays a pixel unit consisting of m rows (vertical direction in the drawing) and n columns (horizontal direction). In the figure, reference numeral 36 denotes a convex lens.

FIG. 6 is an enlarged sectional view of the organic EL device according to the present embodiment.

In FIG. 6, reference numeral 31 denotes a transparent plate, which is composed of a convex lens on the lamination side in pixel units and a flat surface on the observation side as shown in FIG. Reference numeral 32 denotes a transparent electrode, each of which is a thin film having a concave surface on the transparent plate 31 side of the convex lens, and serves as a common electrode in a row direction in which pixels in each vertical direction are connected. Reference numeral 33 denotes a thin-film luminescent color material each having a concave surface on the transparent plate 31 side, and reference numeral 34 denotes a thin-film metal electrode each having a concave surface on the transparent plate 31 side, and forms a concave mirror for each pixel. In addition, a common electrode in the column direction is formed by connecting pixels in each horizontal direction. Reference numeral 35 denotes an insulating plate having a concave surface on the side of the metal electrode 34, which electrically separates the metal electrode 34 from other substances and protects the laminated film as described in the first embodiment. The insulating plate 35 may be a glass plate or an insulating thin film. In the case of an insulating thin film, a circuit board may be added to the surface opposite to the metal electrode 14. Further, when the transparent plate 31 is laminated as a substrate, the insulating plate 35 may not be provided.

FIG. 7 is an enlarged sectional view of a convex lens portion of the transparent plate 31, and FIG. 7A shows an element of the present embodiment.
FIG. 1B shows a conventional device. FIG. 7B shows a case of a transparent plate having no lens similar to that of FIG. 3A as a conventional example, and an angle γ larger than the critical angle θ.
The light emitted from the luminescent layer of the luminescent color material is totally reflected at the glass boundary surface in contact with air on the observation side and does not reach the observation side.

On the other hand, FIG. 7 (a) shows one pixel of FIG. 6, in which light having an emission angle γ emitted from point A is reflected once by a concave mirror of the metal electrode 34, and glass and air The beam reaches the observation side in a direction substantially perpendicular to the boundary surface. In addition, since the direct light from point A also reaches the observation side, and a wide range of light can be reached, FIG.
In this case, the light emission extraction efficiency is increased as compared with the case of, and a bright display can be performed.

Embodiment 4 Hereinafter, a fourth embodiment of the present invention will be described with reference to the drawings.

The present invention relates to a matrix type display element for displaying in pixel units as in the third embodiment.

FIG. 8 is a cross-sectional view of the present embodiment, which is an organic EL device having improved light emission extraction efficiency in a matrix type display.

In FIG. 8, reference numeral 41 denotes a transparent plate, and the lamination side is a convex lens on the lamination side in the same pixel unit as the transparent plate 31 of FIG. 6, and the observation side opposite to the lamination is the first embodiment. One single-sided convex lens is formed by the same display element as in FIG. 42 is a transparent electrode, 43 is a luminescent color material, 44 is a metal electrode, and 45 is an insulating plate.
The same as the transparent electrode 32, the luminescent color material 33, the metal electrode 34, and the insulating plate 35 of FIG.

In this embodiment, in addition to the operation described in the third embodiment, the observation side forms a single convex lens on the entire display element as described above. As described above, an effect that the light emission extraction efficiency is improved as compared with the case where the boundary surface on the observation side is a plane is also added. That is, as compared with the third embodiment shown in FIG. 6, the light emission extraction efficiency is improved, and a bright display can be performed.

(Embodiment 5) Hereinafter, a fifth embodiment of the present invention will be described with reference to the drawings.

The present invention also relates to a matrix type display element for displaying on a pixel-by-pixel basis as in the third embodiment.

FIG. 9 is a cross-sectional view of the present embodiment, which is an organic EL device having improved light emission extraction efficiency in a matrix type display.

In FIG. 9, reference numeral 51 denotes a transparent plate, and the lamination side is a convex lens on the lamination side in the same pixel unit as the transparent plate 31 in FIG. 6, and the observation side opposite to the lamination is the lens on the lamination side. It is a convex lens on the observation side corresponding to the convex lens of each pixel on a one-to-one basis, and one double-sided convex lens is formed for each pixel. 52 is a transparent electrode, 53 is a luminescent color material, 54 is a metal electrode, and 55 is an insulating plate. The transparent electrode 32 in FIG. 6 is the same as the luminescent color material 33, the metal electrode 34, and the insulating plate 35.

FIG. 10 is an enlarged cross-sectional view of the transparent plate 51 of the present embodiment. FIG. 10A shows an element of this embodiment, and FIG. 10B shows an element of a conventional example. FIG. 10 (b) shows a case of a transparent plate having no lens similar to that of FIG. 3 (a), which is a conventional example, in which light emitted from the luminescent layer of the luminescent color material at an angle γ larger than the critical angle θ. Is totally reflected at the glass boundary surface in contact with air on the observation side and does not reach the observation side.

On the other hand, FIG. 10A shows one pixel shown in FIG. 9, and shows the emission angle γ emitted from the point A.
Is once reflected by the concave mirror of the metal electrode, refracted in the convex direction toward the interface between glass and air at the contact point whose normal is the focal point of the convex lens, and reaches the observation side. In addition, since the direct light from point A also reaches the observation side and can reach a wide range of light, the light emission extraction efficiency increases as compared with the case of FIG. 10B, and a bright display can be performed.

In the third, fourth, and fifth embodiments of the matrix type display described above, an example is described in which the matrix display is made up of pixel units. However, as in color display, each of red, green, and blue is displayed. The present invention can be similarly implemented for a matrix constituted by a matrix display in which picture elements each composed of one pixel are used as a unit.

Embodiment 6 Hereinafter, a sixth embodiment of the present invention will be described with reference to the drawings.

The present invention relates to a matrix type color display element for displaying pixels in pixel units with red, green, and blue as one pixel unit.

FIG. 11 is a cross-sectional view of the present embodiment, which is an organic EL device having improved light emission extraction efficiency in a matrix type color display.

In FIG. 11, reference numeral 61 denotes a transparent plate, the lamination side is a plane, and the observation side opposite to the lamination is a convex lens. One single-sided convex lens is formed for each picture element. I have. 62 is a transparent electrode, 63 is a luminescent color material, 64 is a metal electrode, and 65 is an insulating plate. The transparent electrode 32 in the third embodiment shown in FIG.
4. The same as the case where the insulating plate 35 is a flat plate, but the luminescent color material 63 emits red (R), green (G), and blue (B) light for each pixel as one pixel unit. It is divided by color material.

This embodiment can be considered in the same manner as the first embodiment shown in FIG. 1 and FIG.
Therefore, even light emitted at an angle larger than the critical angle θ can reach the observation side, so that the light emission extraction efficiency is increased as compared with the conventional example, and a bright display can be performed.

In the above description, an example was described in which a matrix was displayed in units of picture elements. However, as in the third, fourth and fifth embodiments, a case in which a matrix was displayed in units of pixels was used. Can be similarly implemented.

In the above embodiment, the case where the insulating plate is provided on the metal electrode side has been described. However, it is needless to say that a configuration having no insulating plate can be similarly implemented.

[0054]

As described above, according to the present invention, the organic EL
Make the display observation side of the transparent plate of the display element a convex lens shape,
Alternatively, since the emission color material lamination side is formed into a convex lens shape and the metal electrode is used as a concave mirror, light emission extraction efficiency can be increased, so that an advantageous effect that a display can be brightened without increasing power consumption can be obtained. can get.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of an organic EL display element according to a first embodiment of the present invention.

FIG. 2 is a view showing a transparent plate of the organic EL display element according to the first embodiment.

FIG. 3 is a schematic diagram showing an optical path of the organic EL display element according to the first embodiment.

FIG. 4 is a sectional view of an organic EL display element according to the second embodiment.

FIG. 5 is a schematic view of an organic EL display element according to the third embodiment.

FIG. 6 is a sectional view of an organic EL display element according to the third embodiment.

FIG. 7 is a schematic view showing an optical path of the organic EL display element according to the third embodiment.

FIG. 8 is a sectional view of an organic EL display element according to the fourth embodiment.

FIG. 9 is a sectional view of an organic EL display element according to the fifth embodiment.

FIG. 10 is a schematic diagram showing an optical path of an organic EL display element according to the fifth embodiment.

FIG. 11 is a sectional view of an organic EL display element according to the sixth embodiment.

FIG. 12 is a cross-sectional view of a conventional organic EL display element.

FIG. 13 is a schematic view showing an optical path of a conventional organic EL display element.

[Explanation of symbols]

 11, 21, 31, 41, 51, 61 Transparent plate 12, 22, 32, 42, 52, 62 Transparent electrode 13, 23, 33, 43, 53, 63 Luminescent color material 14, 24, 34, 44, 54, 64 Metal electrode 15, 25, 35, 45, 55, 65 Insulating plate 36 Convex lens 71 Hole injection material 72 Hole transport material 73 Light emitting material 74 Electron transport material

Claims (9)

[Claims] 1. A transparent plate, comprising: a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate, and a surface of the transparent plate that is not in contact with the transparent electrode is one sheet. An organic EL display element having a convex lens shape. 2. An organic EL display device comprising: a transparent plate; a transparent electrode, a luminescent color material, and a metal electrode sequentially laminated on the transparent plate; and both surfaces of the transparent plate are in the form of a single convex lens. 3. A transparent plate, a transparent electrode, a luminescent colorant, and a metal electrode sequentially laminated on the transparent plate, and a surface of the transparent plate in contact with the transparent electrode has a predetermined number of minute convex lens shapes. An organic EL display element. 4. A transparent plate, comprising: a transparent electrode, a luminescent colorant, and a metal electrode sequentially laminated on the transparent plate, wherein a surface of the transparent plate that is not in contact with the transparent electrode is one sheet. An organic EL display element having a convex lens shape, wherein a surface of the transparent plate in contact with the transparent electrode has a predetermined number of minute convex lens shapes. 5. An organic material comprising a transparent plate, a transparent electrode, a luminescent colorant, and a metal electrode sequentially laminated on the transparent plate, and both surfaces of the transparent plate are in the form of a predetermined number of minute convex lenses corresponding to each other. EL display element. 6. A transparent plate, comprising a transparent electrode, a luminescent colorant, and a metal electrode sequentially laminated on the transparent plate, wherein a surface of the transparent plate which is not in contact with the transparent electrode has a predetermined number. An organic EL display element having a shape of a minute convex lens. 7. The organic EL display device according to claim 3, wherein the minute convex lens is formed for each pixel of the matrix type display. 8. The organic EL display element according to claim 3, wherein the minute convex lens is formed for each pixel including one pixel including red, green and blue of a matrix type display. 9. The method according to claim 1, wherein an insulating plate is provided on the metal electrode.
9. The organic EL display device according to any one of items 8 to 8.