JP2003022891A - Organic electroluminescent display device and method of manufacturing the same - Google Patents

Abstract

An object of the present invention is to improve a heat radiation rate from an EL element to the outside of the element, suppress deterioration of light emission characteristics due to heat generated in an organic EL layer, and extend the life of a display element. SOLUTION: An organic electroluminescence display element 1 is composed of at least one of glass, plastic, and ceramic, and is provided with a plurality of electrodes 3, and an organic electroluminescent display laminated on the substrate 2. An upper electrode 5 provided to face the luminescent layer 4 and the substrate 2 with the organic electroluminescent layer 4 interposed therebetween, and a sealing agent 7 via the sealing space 6 between the upper electrode 5 and the upper electrode 5. And a sealing substrate 8 sealed with respect to the sealing substrate 8. The upper side of the upper electrode 5 is formed on the surface 5 a of the upper electrode 5 facing the sealing substrate by film formation and processing, and the projected side wall is formed. A heat radiating portion 10 for releasing heat generated from the organic electroluminescent layer 4 due to the surface area of the organic electroluminescent layer 4.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic electroluminescence display device.

[0002]

2. Description of the Related Art Organic electroluminescence (hereinafter, referred to as
Organic EL-Electro luminescence-. ) A display element is attracting attention because it is a self-luminous element that has an excellent viewing angle and response speed and can be easily thinned. Generally, an organic EL display element has a transparent electrode provided on the substrate side for taking out light emission, and a counter electrode (upper electrode) mainly made of metal, and an organic light emitting layer (hereinafter, EL
It is a structure having layers). This EL layer is composed of a plurality of thin films such as a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer and an electron injection layer. Also, electrodes and EL
It may also have a dielectric such as lithium fluoride between the layers.

The EL layer is formed by a dry process typified by a vacuum vapor deposition method or a wet process typified by a spin coating method. The present invention relates to the formation of an EL layer and is particularly limited. is not. Examples of the film forming method of the counter electrode include a vacuum evaporation method using resistance heating, an electron beam evaporation method, a sputtering method, and the like.
A surface condition that follows the flatness of the layer is obtained. In particular, when the EL layer is formed by a wet process, a flat film is obtained for the EL layer, so that the surface of the counter electrode is also flat. Further, after the EL element is formed, sealing is performed in a special atmosphere such as N ₂ or Ar gas in order to prevent contact with the atmosphere.

The organic EL element is driven by exchanging excitons formed by recombination of electrons and holes in the EL layer as a light emitting layer by passing a current through the EL layer through the lower and upper electrodes. This is due to fluorescence generated by relaxation.

In this organic electroluminescence display element, heat is generated in the display element because the light emitting layer is current-driven. In particular, since the organic EL element is sealed to protect the EL layer, heat radiation to the outside via the counter electrode is unlikely to occur, and this heat easily accumulates in the element. As a result, changes in light emission characteristics due to temperature rise (for example, decrease in light emission efficiency and change in emission color), effects on device life, etc.
It is thought that immeasurable effects will occur.

[0006]

As described above, in the conventional organic electroluminescence display device,
Heat was generated near the electrodes in the display element by passing a current through the electrodes. The heat generated by this display element is remarkable in the vicinity of the electrodes, but since the lower electrode is provided on the substrate such as glass, the heat is propagated from the lower substrate that is in close contact and the heat dissipation is better than that of the upper electrode. Will have. On the other hand, in particular, the upper electrode provided facing the substrate above the EL layer is provided in the sealed space by being sealed by the lower substrate and the sealing substrate via the sealant. Therefore, there is a problem that heat generated by passing a current through the upper electrode is trapped in the display element. Due to the heat accumulated in the display element, there is a problem that a temperature rise occurs and the light emitting characteristics are deteriorated, or the life of the display element is shortened.

The present invention has been made to solve the above-mentioned problems, and suppresses the deterioration of the light emitting characteristics due to the heat generated in the organic EL layer by improving the heat dissipation rate from the EL element to the outside of the element. However, the purpose is to extend the life of the display element.

[0008]

In order to achieve the above object, an organic electroluminescence display device according to a first basic structure of the present invention is composed of at least one of glass, plastic, and ceramic, and a plurality of organic electroluminescence display devices. A substrate provided with an electrode of, an organic electroluminescent layer laminated on the substrate, an upper electrode provided to face the organic electroluminescent layer between the substrate, and the upper electrode. In a organic electroluminescence display element comprising: a sealing substrate sealed to the substrate with a sealing agent via a sealing space between them, a surface of the upper electrode facing the sealing substrate is formed. The surface is formed on the side wall of the protrusion by the film and processing, and the heat generated from the organic electroluminescence layer is released. Characterized in that it comprises a heat radiating portion that.

The method of manufacturing an organic electroluminescence display device according to the second basic structure of the present invention comprises a substrate which is made of at least one of glass, plastic and ceramics and which is provided with a plurality of electrodes. ,
An organic electroluminescence layer laminated on this substrate, an upper electrode provided to face the organic electroluminescence layer between the substrate, and a sealing space between the upper electrode and the upper electrode. In a method for manufacturing an organic electroluminescence display element, comprising: a sealing substrate sealed with respect to the substrate by a sealing agent; a step of forming a transparent electrode on one main surface of the substrate; Forming an organic light emitting layer on the main surface so as to surround the transparent electrode, and forming an upper electrode mainly made of a metal so as to surround the transparent electrode and the organic light emitting layer on the one main surface of the substrate. And a shape corresponding to the predetermined hole pattern by further depositing metal through a shadow mask having a predetermined hole pattern of the upper electrode. And a, and forming a protrusion by laminating.

According to the first and second basic configurations of the present invention, a seal for forming a sealed space sealed with a sealant between the substrate and a substrate provided with a plurality of electrodes as lower electrodes. A large number of protrusions are formed on the surface of the upper electrode facing the stop substrate to increase the surface area, and the increase in the area releases heat generated by the current passed through the upper electrode. The increase in surface area due to the larger number of protrusions than that on a flat plane can greatly improve heat dissipation characteristics. In order to further improve the characteristics for heat dissipation, the shape and arrangement of many protrusions may be formed so as to increase the surface area of the upper electrode on the side of the sealing space.

For that purpose, the formation density of the individual projections should be made as close as possible, and the height should be such that it comes into contact with the inner surface of the sealing substrate. Further, if the base portions of the adjacent protrusions are closely attached to each other as much as possible, and if they are formed in a trapezoidal shape or a truncated cone shape that becomes narrower toward the upper side, that is, in the sealing substrate direction, higher heat dissipation characteristics can be obtained. it can.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the organic electroluminescence display device according to the present invention will be described in detail with reference to the accompanying drawings. First, the organic electroluminescence display element according to the first embodiment of the present invention will be described with reference to FIGS. 1 and 2.

FIG. 1 is a schematic sectional view of the organic electroluminescence display element according to the first embodiment, and the sectional display is omitted in order to avoid complication of the display. In FIG. 1, an organic electroluminescence display device 1 includes a lower substrate 2 made of glass, plastic, ceramics or the like, a plurality of lower electrodes 3 provided on one main surface of the lower substrate 2, and a lower substrate 2 on the substrate 2. An organic electroluminescent layer 4 laminated so as to surround the lower electrode 3, and an upper electrode 5 provided to face the substrate 2 with the organic electroluminescent layer 4 interposed therebetween.
A sealing substrate 8 that is sealed from the lower substrate 2 by a sealant 7 via a sealing space 6 between the upper electrode 5 and the upper electrode 5. The configuration up to this point is the same as that of the conventional organic electroluminescence display element.

The organic electroluminescence display element according to the first embodiment has a heat dissipation portion 10 formed on the surface of the upper electrode 5 facing the sealing substrate 8. The heat dissipation portion 10 is formed and processed. And a large number of protrusions 11 for releasing heat generated from the organic electroluminescence layer due to the surface area of the side wall of the protrusion.

As shown in FIG. 2, the plurality of projections 11 are rectangular step-like projections formed substantially uniformly over a certain range of the facing surface 5a of the upper electrode 5 on the sealing substrate 8 side. The two adjacent projections 11, 11 of the large number of projections are arranged in a substantially orthogonal X direction and a Y direction.
It is provided so as to be separated by a predetermined distance in two directions.
The rectangular step-shaped projection 11 shown in FIG. 2 has a substantially square shape and has a congruent bottom surface and an upper surface, and a rectangular step portion having a height about twice one side of each surface is arranged in a matrix. It has a structure in which a large number are arranged.

In the organic electroluminescent display element according to the first embodiment shown in FIGS. 1 and 2, the heat dissipation portion 10 is formed by selectively laminating a metal film on the surface 5a of the flat metal upper electrode 5. It is formed by. Further, the heat dissipation portion 10 may be formed by selectively etching the flat metal upper electrode 5 after forming the film.

For example, in the case of a vacuum vapor deposition method using a shadow mask, the mask pattern is changed during vapor deposition so that the surface becomes uneven. At this time, the pattern of the shadow mask to be used is a mask having square holes in the case of the first embodiment, but other than that, depending on the shape of the projection to be formed, a stripe-shaped or dot-shaped pattern is used. And so on. Alternatively, the upper electrode 5 having a similar uneven surface can be formed by etching after film formation.
Can be created.

When forming the upper electrode, the method is the same as the conventional method until the shadow mask is changed, but the electrode formed after changing the shadow mask on the way is
The pattern of the shadow mask makes the surface uneven. As a result, the surface area of the upper electrode can be easily increased. By increasing the surface area, diffusion of heat from the upper electrode is promoted, and the heat generated in the element by driving can be diffused to the outside of the element.

Next, the organic electroluminescence display element according to the second embodiment of the present invention will be described with reference to FIGS. 3 and 4. The display element of the second embodiment is characterized in that the heat dissipation portion 10 has a longer protrusion 12 than the protrusion 11 of the first embodiment, and the upper surface 12a of the protrusion 12 is sealed as shown in FIG. It is formed to a height that is in close contact with the lower surface of the substrate on the upper electrode 5 side. In this way, by processing the upper electrode into an uneven shape and forming it into a long shape,
It is also possible to control the gap with the sealing substrate 8 without using a spacer. As an effect peculiar to this configuration, for example, when a TFT array substrate having a driving circuit on the lower substrate is used, the driver is prevented from being damaged by the spacer, and the yield is increased.

Next, an organic electroluminescence display element according to the third embodiment of the present invention will be described with reference to FIGS. 5 and 6. 5 and 6, the same components as those in FIGS. 1 to 4 are designated by the same reference numerals, and a duplicate description will be omitted. The organic electroluminescence display element according to the third embodiment is different from the display elements according to the first and second embodiments in that the heat dissipation portion 10 has a trapezoidal shape.

The specific structure of the heat dissipation portion 10 of the third embodiment is composed of a large number of trapezoidal protrusions 13 having a height up to the middle of the sealed space 6 as shown in FIG. As shown in FIG. 6, the situation is such that the adjacent sides of the trapezoidal bottom surfaces of the two protrusions protruding in the Y direction are in close contact with each other, and in the X direction, they are separated by approximately one jump for the bottom surface of the protrusion 13. Is formed. It is desirable that the arrangement density, the shape of the protrusions, and the like are statistically the density and the shape that have the best heat dissipation characteristics. Since it is considered to be a thing, it is preferable that the shape of the protrusion is such that it can be closely contacted as much as possible to secure a large surface area.

A fourth embodiment shown in FIGS. 7 and 8 can be considered based on the relationship of the second embodiment with respect to the first embodiment. The organic electroluminescence display element according to the fourth embodiment is, as shown in FIG.
A large number of trapezoidal protrusions 14 having an upper surface 14a that contacts the lower surface of the sealing substrate 8 are arranged in two directions X and Y. It is formed so that two adjacent sides of the bottom surface of the protrusion 14 are in close contact with each other. The protrusions 14 of the heat dissipation portion according to the fourth embodiment also function as spacers, like the protrusions 12 of the heat dissipation portion according to the second embodiment.

According to the organic electroluminescence display device according to the above-mentioned first to fourth embodiments,
Each of the large number of protrusions 11 to 14 as the heat dissipation portion 10 has a rectangular prismatic shape or a truncated pyramid shape with a bottom surface, but the present invention is not limited to this, and the large number of protrusions are formed in a cylindrical shape or a truncated cone shape. You may. Also, regarding the arrangement, the heat dissipation portion is composed of a large number of truncated cone-shaped projections formed so as to project substantially uniformly over a certain range of the surface of the upper electrode facing the sealing substrate. Adjacent two of a large number of protrusions may be provided at a predetermined distance in two orthogonal directions. The plurality of protrusions forming the heat radiating portion may be arranged such that protrusion columns of two adjacent rows in the row and column two directions arranged are displaced by a predetermined distance.

9 and 10 are a sectional view and a perspective view showing an organic electroluminescence display device according to a fifth embodiment of the present invention. As shown in FIG. 9, in the organic electroluminescence display element according to the fifth embodiment, a truncated cone-shaped protrusion 15 is provided on the surface 5 a of the upper electrode 5. The protrusions 15 are provided so as to be displaced for each adjacent column and row.

According to the display element of the fifth embodiment, since the projection 15 is formed in a truncated cone shape, a wide surface area can be secured by the conical inclined peripheral surface and the upper electrode can be secured. The thermal convection efficiency at the time of radiating the heat generated by the current of the upper electrode 5 between the upper surface 5a of the electrode 5 and the lower surface of the sealing substrate 8 can be further improved.

The frustoconical shape shown in FIG. 9 is formed at a height halfway between the shape 5a of the upper electrode 5 and the lower surface of the sealing substrate 8 in the sealing space 6. However, the present invention is not limited to this, and as in the heat dissipation parts 12 and 14 shown in the second and fourth embodiments, heat is applied to the lower surface of the sealing substrate 8 and heats the sealing substrate 8 directly on the upper surface of the protrusion. It may be configured to conduct electricity. Further, although the projection 15 of the fifth embodiment is formed in a truncated cone shape, the present invention is not limited to this and is formed in a cylindrical shape that looks like FIG. 1 when viewed from the side cross section. May be. Similarly, it is needless to say that the upper surface that looks like the side cross-sectional view of FIG. 3 may be a cylindrical protrusion that is formed long until it contacts the lower surface of the sealing substrate 8.

A sixth method corresponding to the method for manufacturing an organic electroluminescence display device according to the second basic structure of the present invention.
A method for manufacturing the organic electroluminescence display element according to the embodiment will be described with reference to FIGS. 11 and 12.

The method of manufacturing a display device according to the sixth embodiment is composed of at least one of glass, plastic, and ceramic, and a substrate provided with a plurality of electrodes, and an organic electroluminescent layer laminated on the substrate. A luminescent layer, an upper electrode provided to face the substrate with the organic electroluminescent layer sandwiched between the substrate, and a sealing agent through a sealing space between the upper electrode with respect to the substrate. The present invention relates to a method for manufacturing an organic electroluminescence display device including a sealed sealing substrate.

As shown in FIG. 11A, first, in step ST1, a plurality of transparent electrodes 3 are formed on one main surface 2a of the substrate 2. Next, in step ST2 shown in FIG. 11B, the organic light emitting layer 4 is formed on the one main surface 2a of the substrate 2 so as to surround the transparent electrode 3. Next, as shown in FIG. 11C, in step ST3, an upper electrode 5 mainly made of metal is formed on the one main surface 2a of the substrate 2 so as to surround the transparent electrode 3 and the organic light emitting layer 4. Form a stack. Finally, as shown in FIG. 11D, in step ST4, the upper electrode 5
A plurality of protrusions 1 having a shape corresponding to the predetermined hole pattern 21 are formed by further depositing a metal on the upper surface 5a of the shadow mask 20 having the predetermined hole pattern 21.
6 are sequentially laminated and formed. Formed protrusion 16
Functions as the heat dissipation unit 10 of the first to fifth embodiments.

In the method of manufacturing the organic electroluminescence display element according to the sixth embodiment, the method shown in FIG.
It is formed by metal deposition using a shadow mask 20 having a large number of hole patterns 21 as shown in FIG. By adjusting this hole pattern so that the heat dissipation portion 10 having the shape with the highest heat dissipation efficiency is formed, it is possible to form the protrusion having the most preferable shape and density. In addition,
In order to form the projection 16 in a conical shape, FIG.
At the time of metal deposition using a mask in step ST4 shown in (4), the metal deposition rate may be adjusted to be strong initially and gradually weakened so that the same mask can be deposited in a conical shape. Alternatively, a plurality of masks may be prepared, and a mask having a wide hole in the pattern may be gradually replaced with a mask having a smaller diameter to perform metal deposition.

[0031]

As described in detail above, according to the organic electroluminescence display element and the method for manufacturing the same according to the present invention, the top surface of the upper electrode facing the bottom surface of the encapsulation substrate is formed with irregularities to form a surface shape. Since the area is increased to be the heat dissipation portion, the heat generated in the sealed space of the display element is radiated by the heat dissipation portion to cool the inside of the display element, and the heat dissipation efficiency in the sealed space is improved. It is possible to suppress the deterioration of the light emitting characteristics due to the heat generated in the organic EL layer and to extend the life of the display element.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a schematic configuration of an organic electroluminescence display device according to a first embodiment of the present invention.

FIG. 2 is a perspective view showing a heat generating portion of the organic electroluminescence display element according to the first embodiment of the present invention.

FIG. 3 is a side sectional view showing a schematic configuration of the organic electroluminescence display element according to the first embodiment of the present invention.

FIG. 4 is a perspective view showing a heat generating portion of the organic electroluminescence display element according to the second embodiment of the present invention.

FIG. 5 is a side sectional view showing a schematic configuration of an organic electroluminescence display device according to a third embodiment of the present invention.

FIG. 6 is a perspective view showing a heat generating portion of an organic electroluminescence display device according to a third embodiment of the present invention.

FIG. 7 is a side sectional view showing a schematic configuration of an organic electroluminescence display device according to a fourth embodiment of the present invention.

FIG. 8 is a perspective view showing a heat generating portion of the organic electroluminescence display element according to the fourth embodiment of the present invention.

FIG. 9 is a side sectional view showing a schematic configuration of an organic electroluminescence display element according to a fifth embodiment of the present invention.

FIG. 10 is a perspective view showing a heat generating portion of the organic electroluminescence display element according to the fifth embodiment of the present invention.

FIG. 11 is a schematic step (a) of a method for manufacturing an organic electroluminescence display device according to a sixth embodiment of the present invention.
It is a sectional side view which shows each (d).

FIG. 12 is a plan view showing a shadow mask used in a method of manufacturing an organic electroluminescence display device according to a sixth embodiment of the present invention.

[Explanation of symbols]

1 Organic electroluminescence display device 2 Lower substrate (glass, plastic, ceramic) 3 transparent electrodes 4 Organic electroluminescence layer 5 Upper electrode 6 sealed space 7 Sealant 8 Sealing substrate 10 Heat sink 11-15 protrusions 16 Protrusion 20 shadow mask 21 hole pattern

Claims (6)

[Claims] 1. A substrate composed of at least one of glass, plastic, and ceramic and provided with a plurality of electrodes, an organic electroluminescence layer laminated on the substrate, and the substrate. An upper electrode provided to face each other with the organic electroluminescent layer interposed therebetween, and a sealing substrate sealed with respect to the substrate by a sealing agent via a sealing space between the upper electrode, In an organic electroluminescence display element, the heat dissipation is formed by projecting and forming on the surface of the upper electrode facing the sealing substrate by film formation and processing, and radiating heat generated from the organic electroluminescence layer by the surface area of the projecting side wall. An organic electroluminescence display device, characterized by comprising: 2. The organic electroluminescence display element according to claim 1, wherein the heat dissipation portion has an uneven portion provided on the surface of the upper electrode. 3. The heat dissipating portion is composed of a large number of step-like projections formed to project substantially uniformly over a certain range of the surface of the upper electrode facing the sealing substrate. 2. The organic electroluminescence display element according to claim 1, wherein the two adjacent to each other are spaced apart by a predetermined distance in two orthogonal directions. 4. The heat dissipation part comprises a plurality of protrusions arranged in a matrix on the surface of the upper electrode, and the protrusion columns of two adjacent rows are displaced by a predetermined distance. The organic electroluminescence display element according to claim 1. 5. The projection according to claim 3, wherein the plurality of protrusions forming the heat dissipation portion are formed at a height that abuts on a surface of the sealing substrate facing the upper electrode. Organic electroluminescence display device. 6. A substrate formed of at least one of glass, plastic, and ceramic and provided with a plurality of electrodes, an organic electroluminescence layer laminated on the substrate, and the substrate. An upper electrode provided to face each other with the organic electroluminescent layer interposed therebetween, and a sealing substrate sealed with respect to the substrate by a sealing agent via a sealing space between the upper electrode, In the method for manufacturing an organic electroluminescence display device, comprising: forming a transparent electrode on one main surface of the substrate; and forming an organic light emitting layer on the one main surface of the substrate so as to surround the transparent electrode. Stacking an upper electrode mainly made of metal so as to surround the transparent electrode and the organic light emitting layer on the one main surface of the substrate, A step of stacking and forming a protrusion having a shape corresponding to the predetermined hole pattern by further vapor-depositing a metal on the upper surface of the upper electrode through a shadow mask having a predetermined hole pattern, and the organic electroluminescence display comprising: Device manufacturing method.