KR100685836B1 - Organic light-emitting device - Google Patents

Abstract

An organic light-emitting device is provided to obtain a reflection type first electrode having no corrosion caused by a galvanic phenomenon and enhance an adhesive strength of a metal reflection layer. In an organic light-emitting device, a first electrode(110) includes a reflection metal layer(110a) placed on a substrate(100), and a transparent conductive layer(110b) placed on the reflection metal layer(110a). An organic layer(155) is placed on the first electrode(110), and includes at least an organic light emitting layer(140). A second electrode(160) is placed on the organic layer(155).

Description

Organic Light-Emitting Device

1 is a cross-sectional view illustrating a method of manufacturing an organic light emitting display device according to the prior art.

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

3 is a graph showing reflectance for each wavelength of the first electrode according to the thickness of the transparent conductive film.

Explanation of symbols on the main parts of the drawings

100 substrate 110 first electrode

110a: reflective metal film 110b: transparent conductive film

120: pixel defining layer 130: hole transport layer

140: organic light emitting layer 150: electron transport layer

155: organic layer 160: second electrode

The present invention relates to an organic light emitting display device, and more particularly, to a method of manufacturing an organic light emitting display device which can improve reflectance and minimize dark spot defects.

A general organic light emitting display device includes a first electrode, an organic light emitting layer on the first electrode, and a second electrode on the organic light emitting layer. In the organic light emitting device, when a voltage is applied between the first electrode and the second electrode, holes are injected into the organic light emitting layer from the first electrode, and electrons are injected into the organic light emitting layer from the second electrode. The holes and electrons injected into the organic light emitting layer recombine in the organic light emitting layer to generate excitons, and the excitons emit light while transitioning from the excited state to the ground state.

In the organic light emitting diode, the first electrode is formed to be reflective, that is, to reflect light, and the second electrode is formed to be transmissive, that is, to transmit light, thereby emitting light emitted from the organic light emitting layer. It is possible to manufacture a top-emitting organic light emitting device emitting in a direction.

At this time, as the reflective first electrode, a conductive material having excellent reflection characteristics and an appropriate work function is suitable, but there is currently no single material that satisfies these characteristics and is applicable. Therefore, the above characteristics are satisfied by forming the reflective first electrode in a multilayer structure.

1 is a cross-sectional view illustrating a method of manufacturing an organic light emitting display device having a reflective first electrode according to the prior art.

Referring to FIG. 1, a reflective metal film 12a is formed of aluminum or an aluminum alloy on a substrate 10, and then indium tin oxide (ITO) or indium zinc oxide (IZO) is formed on the reflective metal film 12a. A transparent conductive film 12b is formed.

Subsequently, a photoresist pattern is formed on the transparent conductive film 12b, and the transparent conductive film 12b and the reflective metal film 12a are sequentially etched using the photoresist pattern as a mask. As a result, the first electrode 12 in which the reflective metal film 12a and the transparent conductive film 12b are sequentially stacked is formed. Then, the photoresist pattern is removed using a strip solution.

Next, an organic light emitting diode is manufactured by forming an organic film layer including at least an organic light emitting layer (not shown) on the first electrode 12 and forming a second electrode (not shown) on the organic film layer. .

In the first electrode 12, the transparent conductive film 12b has a high work function, and the reflective metal film 12a formed of aluminum or the like is a film having excellent reflection characteristics. Therefore, the first electrode 12 can easily inject holes into the organic light emitting layer, and can efficiently reflect light emitted from the organic light emitting layer.

However, in general, the reflective metal film 12a and the ITO film 12b formed of aluminum have a large work function difference, and the interface property therebetween deteriorates, which causes a problem of causing a decrease in reflectance.

In addition, in removing the photoresist pattern after etching the reflective metal film 12a and the transparent conductive film 12b, the reflective metal film 12a and the transparent conductive film 12b are exposed to the strip solution at the same time. Corrosion may occur between the metal film 12a and the transparent conductive film 12b due to a galvanic phenomenon. Accordingly, the reflective metal film 12a is formed in an island structure to prevent the reflective metal film 12a and the transparent conductive film 12b from being simultaneously exposed to the stripping solution. There was a need to separately pattern the transparent conductive film 12b.

Accordingly, an object of the present invention is to provide an organic electroluminescent device capable of improving the reflectance and minimizing dark spot defects, which is devised to solve the problems of the prior art as described above.

In order to achieve the above technical problem, the present invention, a substrate; A first electrode including a reflective metal film on the substrate and a transparent conductive film on the reflective metal film; An organic layer disposed on the first electrode and including at least an organic light emitting layer; It includes a second electrode located on the organic film layer, the thickness of the transparent conductive film provides an organic light emitting device, characterized in that 75 to 100Å.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings in order to describe the present invention in more detail. However, the present invention is not limited to the embodiments described herein but may be embodied in other forms. Rather, the embodiments introduced herein are provided so that the disclosure may be made thorough and complete, and to fully convey the spirit of the present invention to those skilled in the art. In the figures, where a layer is said to be "on" another layer or substrate, it may be formed directly on the other layer or substrate, or a third layer may be interposed therebetween. Like numbers refer to like elements throughout the specification.

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

Referring to FIG. 2, a substrate 100 having a predetermined substructure is provided. The substrate 100 includes at least one thin film transistor in the case of an active matrix organic light emitting diode.

The reflective metal film 110a is formed on the substrate 100. The reflective metal film 110a is a metal film that reflects light, and is preferably formed of a metal having excellent reflection characteristics, that is, silver (Al) or silver alloy (Al alloy). Such reflective metal materials generally have a low work function.

The reflective metal film 110a is preferably formed using sputtering. In addition, the reflective metal film 110a is preferably formed to have a thickness of 500 Å or more so as to exhibit appropriate reflection characteristics.

Subsequently, a transparent conductive film 110b is formed on the reflective metal film 110a. The transparent conductive film 110b may be formed using indium tin oxide (ITO) or indium zinc oxide (IZO) having a high work function.

Here, the thickness of the transparent conductive film (110b) is preferably 75 to 100Å.

When the thickness of the transparent conductive film 110b is less than 75Å, the thickness of the transparent conductive film 110b is not uniformly formed, so that the reflective metal film 110a formed at the bottom may be exposed. Since the reflective metal film 110a is exposed to the outside of the transparent conductive film 110b in a subsequent cleaning process because it is a very good material, oxidation proceeds quickly and projections occur due to an increase in volume due to oxidation. It may cause a defect. In addition, when the thickness of the transparent conductive film 110b is greater than 100 μs, the reflectance of the blue light emitting layer may decrease due to interference.

Subsequently, a photoresist pattern is formed on the transparent conductive film 110b, and the transparent conductive film 110b and the reflective metal film 110a are sequentially etched using the photoresist pattern as a mask to thereby form the reflective metal film 110a. And the transparent conductive film 110b are sequentially formed to form the reflective first electrode 110. Then, the photoresist pattern is removed using a strip solution.

In the first electrode 110, since a silver or a silver alloy having good reflectance is used as the reflective metal film 110a, the reflective characteristics of the first electrode 110 may be improved. In addition, in removing the photoresist pattern using the strip solution, even if the reflective metal film 110a and the transparent conductive film 110c are simultaneously exposed to the strip solution, the reflective metal film 110a formed of silver and The galvanic phenomenon does not occur between the transparent conductive films, so that they can be collectively etched, thereby shortening the process time.

Here, in order to increase the adhesion between the reflective metal film 110a and the substrate, a transparent conductive film may be further provided below the reflective metal film 110a.

As described above, when the first electrode 110 is formed, the surface of the first electrode 110 is washed with water, and then a pixel defined layer 120 is formed on the transparent conductive film 110c. do.

Next, the pixel definition layer 120 is exposed using a photomask to expose a predetermined region of the transparent conductive layer 110c in the pixel definition layer 120 to define an opening 120a defining a light emitting area. Form. The pixel definition layer 120 may be formed of one selected from the group consisting of benzocyclobutene (BCB), acrylic photoresist, phenolic photoresist, and polyimide photoresist.

Then, an organic layer 155 including at least an organic light emitting layer 140 is formed on the exposed transparent conductive layer 110c. In forming the organic layer 155, it is preferable to form a hole transport layer 130 on the transparent conductive layer 110c before forming the organic light emitting layer 140. More preferably, before the hole transport layer 130 is formed, a hole injection layer (not shown) is formed on the transparent conductive film 110c. In addition, in forming the organic layer 155, it is preferable to form the electron transport layer 150 on the organic light emitting layer 140. More preferably, an electron injection layer (not shown) is formed on the electron transport layer 150.

Subsequently, a second electrode 160 is formed on the organic layer 155. The second electrode 160 is formed using one metal selected from the group consisting of Mg, Ca, Al, Ag, Ba, and alloys thereof, but is preferably formed to a thickness sufficient to transmit light. Do.

As a result, an organic light emitting display device including the reflective first electrode 110, the second electrode 160, and the organic layer 155 interposed therebetween can be manufactured.

As described above, the present invention forms a transparent conductive film with a thickness of 75 to 100 GPa on the reflective metal film to ensure uniformity of the thickness of the transparent conductive film, thereby preventing dark spot defects due to exposure of the reflective metal film. have.

In addition, the present invention can improve the reflectance and prevent the corrosion phenomenon due to galvanic phenomenon by using silver or silver alloy as a reflective metal film.

In addition, the present invention can further improve the adhesion of the reflective metal film by further comprising a transparent conductive film under the reflective metal film.

Hereinafter, the present invention will be exemplified by the following experimental example, but the protection scope of the present invention is not limited by the following experimental example.

Experimental Example 1

Sputtering was performed on the substrate to form a silver alloy film having a thickness of about 1000 mW, and a transparent conductive film having a thickness of about 75 mW was formed on the silver alloy film by using IZO. Subsequently, a photoresist pattern was formed on the transparent conductive film, and the reflective first electrode was formed by sequentially etching the transparent conductive film and the silver alloy film using the photoresist pattern.

Experimental Example 2

A reflective type was formed in the same manner as in the experimental examples except that a sputtering was performed on the substrate to form a silver alloy film having a thickness of about 1000 mW, and a transparent conductive film was formed on the silver alloy film with a thickness of 200 mW using IZO. The first electrode was formed.

Comparative Example 1

The reflective type was formed by sputtering on the substrate to form a silver alloy film having a thickness of about 1000 mW, and a transparent conductive film having a thickness of 50 mW using IZO on the silver alloy film. The first electrode was formed.

Experimental Example 1 Experimental Example 2 Comparative example One 2 3 4 One 2 One 2 3 4 5 Dark spot number 6 5 5 7 5 5 9 10 16 16 23 Average 6 5 14.8

Table 1 is a table showing the number of dark spots generated per unit pixel of the organic light emitting display device manufactured according to Experimental Examples 1, 2 and Comparative Examples.

As described above, in Experimental Example 1 in which the transparent conductive film was formed on the silver alloy film at a thickness of 75 kPa and Experimental Example 2 formed at a thickness of 200 kPa, the number of dark spots was 2.5 times higher than that of the comparative example formed at the thickness of 50 kPa. It can be seen that the abnormal decrease. In addition, since the number of dark spots is no longer reduced even when the transparent conductive film is formed at 200 μs, it can be seen that when the transparent conductive film is formed at 75 μs or more, uniformity of the thickness of the transparent conductive film can be ensured, thereby minimizing dark spot defects. .

3 is a graph measuring reflectance for each wavelength according to the thickness of the transparent conductive film. Based on the reflectance of the aluminum alloy (A), a reflective metal film is formed of silver and on the reflective metal film is 50 Å (B), 70 Å (C), 100 Å (D), 140 Å (E) and 250 Å (F). After forming each transparent conductive film, the reflectance for each wavelength was measured.

Referring to FIG. 3, when the thickness of the transparent conductive film 110b exceeds 100 μs (D), since the reflectance of the blue light emitting layer is lowered to 80% or less than that of the aluminum alloy, the thickness of the transparent conductive film 110b is 100 μs. It is understood that the following is preferable.

As described above, according to the present invention, it is possible to obtain a reflective first electrode having increased reflectance and no corrosion due to galvanic phenomenon. In addition, the present invention can prevent the dark spot defect due to the exposure of the metal reflection film, it is possible to improve the adhesion of the metal reflection film.

Therefore, the present invention can implement an organic light emitting display device having an improved reliability and improved screen quality.

Claims (4)

Board; A first electrode including a reflective metal film on the substrate and a transparent conductive film on the reflective metal film; An organic layer disposed on the first electrode and including at least an organic light emitting layer; A second electrode positioned on the organic layer; The thickness of the transparent conductive film is an organic light emitting device, characterized in that 75 to 100Å. The method of claim 1, The reflective metal film is an organic light emitting device, characterized in that made of silver (Ag) or silver alloy (Ag alloy). The method of claim 1, The transparent conductive film is an organic electroluminescent device, characterized in that made of indium tin oxide (ITO) or indium zinc oxide (IZO). The method of claim 1, The first electrode further comprises a transparent conductive film under the reflective metal film.

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