KR100784546B1 - Organic light emitting device - Google Patents

Abstract

An organic light emitting diode is provided to prevent a life span and the reliability of the organic light emitting diode caused by deterioration of the organic light emitting diode from being deteriorated. An organic light emitting diode includes a substrate(22), a first electrode(24), an organic light emitting layer(26), a second electrode(28), and more than one protrusion(30). The substrate has a groove. The first electrode is formed on the substrate. The organic light emitting layer is formed on the first electrode. The second electrode is formed on the organic light emitting layer. The protrusion is formed on sides of the first and the second electrodes and has a height 40~80 times higher than a length of a long side of a section of the protrusion. The sides of the first and second electrodes are opposite sides to the organic light emitting layer.

Description

Organic Light Emitting Device

1 is a cross-sectional view showing a state in which light of a conventional organic light emitting diode is extracted;

2 is a cross-sectional view of an organic light emitting display device according to a first embodiment of the present invention;

3 is a plan view of an organic light emitting display device according to a first exemplary embodiment of the present invention;

4 is a cross-sectional view of an organic light emitting display device according to a second exemplary embodiment of the present invention.

5A and 5B are cross-sectional views of organic light emitting diodes according to third and fourth embodiments of the present invention.

6 is a cross-sectional view of an organic light emitting display device according to a fifth exemplary embodiment of the present invention.

* Description of the main parts of the drawings *

12, 22, 42, 62, 82, 102: substrate

14, 24, 44, 64, 84, 106: first electrode

16, 26, 46, 66, 86, 108: light emitting layer

18, 28, 48, 68, 88, 110: second electrode

23, 30, 50, 70, 90, 107, 112: protrusion

104: transparent film

The present invention relates to an organic electroluminescent device.

In general, an organic light emitting display device is a self-light emitting device that emits light by electrically exciting a fluorescent organic compound. The organic light emitting display device in which the organic light emitting diode is applied has a low driving voltage, is easy to thin, and has a wide viewing angle. In addition, the response speed is attracting attention as the next generation display.

The light efficiency of an organic light emitting diode is divided into an internal efficiency and an external efficiency. Among them, the internal efficiency depends on the photoelectric conversion efficiency of the organic light emitting material, and the external efficiency, also called light coupling efficiency, is due to the refractive index of each layer constituting the organic light emitting device.

When the light emitted from the organic light emitting layer is emitted above the critical angle, the organic light emitting diode emits total reflection at an interface between a layer having a high refractive index such as an electrode layer and a layer having a low refractive index such as a passivation film or a substrate. Therefore, the light emitted from the organic light emitting layer is lost in the process of being taken out to the outside, and only about 1/4 of the light emitted from the organic light emitting layer is emitted.

1 is a cross-sectional view showing a state in which light of a conventional organic light emitting diode is extracted;

Referring to FIG. 1, a first electrode 14, an organic emission layer 16, and a second electrode 18 are stacked on a substrate 12.

In the electroluminescent device 10, holes and electrons are supplied to the organic light emitting layer 16 through the first and second electrodes 14 and 18, and the supplied holes and electrons are recombined to generate excitons. Since this excitons change to the ground state, it emits light.

However, in the conventional electroluminescent device, light emitted from the light emitting layer is mostly extinguished and lost due to scattering, overlapping, reflection, and diffuse reflection on the interface with each other, resulting in low light extraction efficiency. Accordingly, in order to improve the brightness of the electroluminescent device Increasing the driving power accelerates deterioration of the device, resulting in deterioration of lifetime and reliability.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide an organic light emitting display device having high light extraction efficiency and excellent luminance characteristics.

In addition, an object of the present invention is to provide an organic light emitting device that can solve the problem of degradation of life and reliability due to deterioration of the device.

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An organic light emitting display device according to an embodiment of the present invention includes a substrate having a groove, a first electrode formed on the substrate, an organic light emitting layer formed on the first electrode, and a second electrode formed on the organic light emitting layer. And at least one protrusion is formed on a surface of the second electrode that does not face the organic light emitting layer, and the protrusion may have a height of 40 to 80 times the length of the longest side of the cross section of the protrusion.
In addition, the length of the longest side of the cross section of the protrusion may range from 0.25 mm to 0.45 mm.
In addition, the width between the protrusions may be 0.7 times to 1 times the height of the protrusions.
In addition, the groove formed between the protrusion and the protrusion may be the same.
In addition, the protrusion may be any one of a polygonal columnar shape or a truncated polygonal pyramidal shape, a polygonal pyramidal shape, a cone shape, a cylinder shape, and a cone shape.
In addition, the first electrode and the second electrode transmit light, and a plurality of protrusions may be formed on a surface not facing the organic light emitting layer.
In addition, a transparent film in which at least one groove is formed between the first electrode and the second electrode, which is relatively close to the substrate, and the substrate may be further formed.
Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

2 is a cross-sectional view of an organic light emitting display device according to a first embodiment of the present invention.

2, in the organic light emitting display device 20 according to the first exemplary embodiment of the present invention, grooves 22a (grooves or recesses) are formed on an upper surface of the substrate 22.

In addition, a first electrode 24 having a first protrusion 23 is formed on the substrate 22 so as to correspond to the groove 22a.

The organic light emitting layer 26 is formed on the first electrode 24. The second electrode 28 having one or more second protrusions 30 is formed on a side of the organic light emitting layer 24 that does not face the organic light emitting layer 24.

Accordingly, the first electrode 24 and the second electrode 28 are disposed to face each other with respect to the organic light emitting layer 24. The first protrusions 23 and the second protrusions 30 are formed on the side surfaces of the first electrode 24 and the second electrode 28 that do not face the organic light emitting layer 24, respectively.

3 is a plan view of an organic light emitting display device according to a first exemplary embodiment of the present invention.

Referring to FIG. 3, a plurality of second protrusions 30 having a square cross section is formed on the second electrode 28 of the organic light emitting diode 20.

Although not shown in FIG. 3, a plurality of first protrusions 23 having a square cross section is formed on one side of the first electrode 22.

In this case, the cross section of the protrusion is not limited to a square, and any one or a shape of a polygon including a triangle, a polygon including a rectangle, an oval, and an irregular closed curve may be a polygon, and the remaining part may be circular.

2 and 3, the height A of the second protrusion 30 is a ratio of 40 times to 80 times the length of one side B of the cross section of the second protrusion 30. The length ratio of the height A of the second protrusion 30 and one side B of the cross section of the second protrusion 30 is a ratio for optimizing the light converging effect of the second protrusion 30.

If the height A of the second protrusion 30 is smaller than the length of one side B of the cross section of the second protrusion 30, it is difficult to pattern the second protrusion 30, so that the yield is very low. There is a problem.

One side B of the cross section of the second protrusion 30 may be formed in a range of 0.25 mm to 0.45 mm.

This is because a plurality of small patterns are required in the second protrusion 30 to solve the problem of total reflection of the emitted light.

Specifically, when one side B of the cross section of the second protrusion 30 is formed in the range of 0.25 mm to 0.45 mm, the patterning of the second protrusion 30 is facilitated, and the second protrusion may exist in one subpixel. This is because the number of 30 is optimized.

Therefore, the length of one side (B) of the cross section of the second protrusion 30 is preferably formed in the range of 0.25 Å to 0.45 Å for the optimal total reflection refractory effect on the emitted light, but is not limited thereto.

Meanwhile, the width C of the groove formed between the second protrusions 30 may be formed at a ratio of 0.7 times to 1 times the height A of the second protrusions 30.

This is because when the width C of the groove formed between the second protrusions 30 becomes too large, the space B for scattering the emitted light and emitting the light within a range within the critical angle is reduced, and the second protrusions 30 may exist in one subpixel. This is because the total number of refraction prevention effects on the outgoing light is relatively reduced due to the decrease in the number of.

Therefore, in order to prevent the total reflection reflection for the emitted light, the width C of the groove formed between the second protrusions 30 is formed at a ratio of 0.7 to 1 times the height A of the second protrusions 30. Preferably, but not limited to.

The size ratio of the second protrusion 30 described above with reference to the drawings may be equally applied to the first protrusion 22a.

In addition, although the first protrusion 23 is formed to correspond to the groove 22a formed on the substrate 22, it has been described with reference to the drawing, but the first electrode 24 is disposed between the substrate 22 and the first electrode 24. A transparent film having grooves 22a may be further formed on the side opposite to the first protrusion 23.

In the organic light emitting display device 20 according to the first embodiment of the present invention described above, the first and second protrusions 23 and 30 formed on the first and second electrodes 24 and 28 are optically convex. It serves to adjust the emission angle or reflection angle of the light emitted from the organic light emitting layer 26 in the device within the range of the critical angle increases the light extraction efficiency.

4 is a cross-sectional view of an organic light emitting display device according to a second exemplary embodiment of the present invention.

Referring to FIG. 4, in the organic light emitting diode 40 according to the second exemplary embodiment of the present invention, a first electrode 44 is formed on a substrate 42.

In this case, the first electrode 44 may be formed of, for example, an opaque conductive film such as aluminum.

Accordingly, since the first electrode 44 reflects the emitted light in a direction opposite to the substrate, the organic light emitting display device 40 according to the second embodiment of the present invention has the substrate 40 as a top emission structure. The screen can be implemented in the opposite direction.

The organic light emitting layer 46 is formed on the first electrode 44.

In addition, on the organic light emitting layer 46, a second electrode 48 having one or more protrusions 50 and transmissive light in a direction opposite to the substrate is formed.

At this time, the structure and pattern of the protrusion 50 follow the same principle as the first embodiment of the present invention.

In the organic light emitting display device 40 according to the second embodiment of the present invention having the structure as described above, the protrusion 50 is optically convex with respect to light emitted from the organic light emitting layer 44 in the opposite direction to the substrate 42. In order to improve the light extraction efficiency according to the same principle as the second protrusion (28 of FIG. 2) of the first embodiment of the present invention.

In addition, since the first electrode 44 acts as a reflecting film in a direction opposite to the substrate 42 with respect to light emitted from the organic light emitting layer 44 toward the substrate 42, the second embodiment 40 of the present invention Compared with the first embodiment 20 of the present invention, the amount of emitted light is increased, and thus the light extraction efficiency can be further improved.

5A and 5B are cross-sectional views of organic light emitting diodes according to third and fourth embodiments of the present invention.

5A and 5B, first electrodes 64 and 84 are formed on the substrates 62 and 82.

Organic light emitting layers 66 and 86 are formed on the first electrodes 64 and 84.

On the organic light emitting layers 66 and 86, second electrodes 68 and 88 having light transmission and having at least one protrusion 70 and 90 in opposite directions to the substrates 62 and 82 are formed.

In the structure of the protrusions 70 and 90 of the electroluminescent devices 60 and 80 according to the third and fourth embodiments of the present invention, grooves formed between the protrusions 70 and 90 have at least one inclined surface, curved surface, or both. Characterized in having a.

Due to the shape of the grooves, the electroluminescent devices 60 and 80 according to the third and fourth embodiments of the present invention may have more protruding portions than the electroluminescent devices 20 and 40 according to the first and second embodiments of the present invention. 70, 90) The light scattering effect is better in the structure. Accordingly, the light extraction efficiency of the light emitted from the second electrodes 68 and 88 to the protrusions 70 and 90 of the emitted light is further improved.

In the above electroluminescent devices according to various embodiments of the present invention, the shape of the protrusion may be the same as any one of a polygonal column shape or a truncated polygonal cone shape, a polygonal cone shape, a cone shape, a cylinder shape, and a cone shape. It may be formed to have a curved surface on a part.

For example, the polygonal pillar shape may be a square pillar shape in which one of the cabinets is 100 ° to 160 °, or a triangular pillar shape in which one of the cabinets is 30 ° to 70 °.

In addition, in the electroluminescent devices according to various embodiments of the present invention, the protrusions may be patterned in various types including a stripe shape and a mesh shape.

6 is a cross-sectional view of an organic light emitting display device according to a fifth embodiment of the present invention.

The organic light emitting display device 100 according to the fifth embodiment of the present invention follows the same electrode structure and optical principle as the first embodiment of the present invention.

Referring to FIG. 6, a transparent film 104 having one or more grooves 104a formed on the substrate 102 is formed in a film form.

The first electrode 106 is formed on the transparent film 104 is formed, the first electrode 106 has a projection 107 by the groove (104a) of the transparent film 104.

The light emitting layer 108 and the second electrode 110 are formed on the first electrode 104, and the second electrode 110 has one or more protrusions 112 on the side that does not face the light emitting layer 108.

In the fifth exemplary embodiment of the present invention, the groove 104a formed in the transparent film 104 has been described with reference to the formation of the substrate 102 so that the substrate 102 is exposed. However, the groove 104a is formed in a part of the thickness of the transparent film 104a. It may be formed in the form of a groove or a recess to a corresponding depth.

In the various embodiments of the present invention, the second electrode has been described with reference to the one or more protrusions on the side which does not face the substrate, but the present invention is not limited thereto, and the second electrode is formed on the organic light emitting layer. On the second electrode, a transparent film having at least one protrusion may be further formed on a side of the second electrode that does not face the substrate.

In addition, the transparent film may be formed of an insulating film or a conductive layer, and the conductive layer may be formed of the same material as the first electrode or the second electrode.

Although the electrode structure of the electroluminescent device according to various embodiments of the present invention has been described with reference to the illustration that the grooves between the protrusions and the protrusions are substantially the same and are regularly patterned and repeated, the electroluminescence of the present invention. The electrode structure of the device is not limited thereto, and two or more patterns may be mixed.

While various embodiments of the present invention have been described above with reference to the accompanying drawings, the above-described technical configuration of the present invention may be embodied by those skilled in the art to which the present invention pertains without changing the technical spirit or essential features of the present invention. It will be appreciated that the present invention may be practiced as. Therefore, the embodiments described above are to be understood as illustrative and not restrictive in all aspects. In addition, the scope of the present invention is shown by the claims below, rather than the above detailed description. In addition, all changes or modifications derived from the meaning and scope of the claims and equivalent concepts should be interpreted as being included in the scope of the present invention.

According to the organic light emitting device of the present invention made as described above can greatly improve the light extraction efficiency.

In addition, it is possible to solve the problem of deterioration of lifetime and reliability caused by deterioration of the device.

Claims (8)

A grooved substrate; A first electrode formed on the substrate; An organic light emitting layer formed on the first electrode; And A second electrode formed on the organic light emitting layer; Wherein the first electrode and the second electrode have at least one protrusion formed on a surface of the first electrode and the second electrode that do not face the organic light emitting layer, and the protrusion has a length of 40 to 80 times the length of the longest side of the cross section of the protrusion. An organic light emitting display device having a height. The method of claim 1, The length of the longest side of the cross section of the protrusion is an organic light emitting device, characterized in that the range of 0.25Å to 0.45Å. delete The method of claim 1, The width between the protrusion and the organic light emitting device, characterized in that 0.7 to 1 times compared to the height of the protrusion. The method of claim 1, The grooves formed between the protrusions are the same. The method of claim 1, The protrusion is an organic light emitting device, characterized in that any one of a polygonal columnar or truncated polygonal pyramidal shape, polygonal pyramidal shape, cone shape, cylinder shape, cone shape. The method of claim 1, The first electrode and the second electrode transmits light, and the organic light emitting device, characterized in that the plurality of protrusions are formed on a surface not facing the organic light emitting layer. The method of claim 1, An organic electroluminescent device according to claim 1, further comprising a transparent film having at least one groove formed between the first electrode and the second electrode, the electrode close to the substrate and the substrate.

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