KR20040019186A - Organic electro luminescence display device and method of manufacturing the same - Google Patents

Abstract

PURPOSE: An organic electro-luminescence device and a fabricating method thereof are provided to prevent a scattering phenomenon of light and enhance the light focusing efficiency by installing a light focusing unit on an optical path. CONSTITUTION: An organic electro-luminescence device includes a transparent substrate(100), a pixel forming unit(110), a driving unit(120), and a light focusing unit. The pixel forming unit(110) is formed with a first electrode layer, an organic layer, an insulating layer, and a second electrode layer. The first electrode layer is formed on a substrate. The organic layer is formed on the first electrode layer. The insulating layer is formed on the organic layer. The second electrode layer is formed on the insulating layer. The driving unit(120) includes TFTs to switch transparent electrodes. The light focusing unit includes a concave lens and a convex lens.

Description

Organic electroluminescent display device and method of manufacturing the same {Organic electro luminescence display device and method of manufacturing the same}

The present invention relates to an organic electroluminescent display, and more particularly, to an organic electroluminescent display having improved focusing efficiency of light generated by an organic film and a method of manufacturing the same.

In general, an organic light emitting display device is a self-luminous display that electrically excites fluorescent organic compounds and emits light, and can be driven at low voltage, is easy to thin, and is pointed out as a problem in liquid crystal display devices such as wide viewing angle and fast response speed. It is attracting attention as the next generation display that can solve the shortcomings.

In the organic light emitting diode display, an organic layer having a predetermined pattern is formed on glass or other transparent insulating substrate, and electrode layers are formed on upper and lower portions of the organic layer. The organic film consists of organic compounds. Materials for forming such organic films include phthalocyanine (CuPc: copper phthalocyanine), N, N-di (naphthalen-1-yl) -N, N'-diphenyl-benzidine (N, N'-Di (naphthalene-1) -yl) -N, N'-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum (Alq3), etc. are used.

In the organic light emitting display device configured as described above, as the anode and cathode voltages are applied to the electrodes, holes injected from the electrode to which the anode voltage is applied are moved to the light emitting layer via the hole transport layer, and the electrons have a cathode voltage. It is injected from the applied electrode into the light emitting layer via the electron transport layer. In this light emitting layer, electrons and holes recombine to produce excitons, and as the excitons change from the excited state to the ground state, the fluorescent molecules in the light emitting layer emit light to form an image.

The light efficiency of the organic light emitting display device driven as described above is divided into internal efficiency and external efficiency. The internal efficiency depends on the photoelectric conversion efficiency of the organic light emitting material, The external efficiency, also called light coupling efficiency, is due to the refractive index of each layer constituting the organic light emitting display. Among them, the light extraction efficiency, which is an external efficiency, is lower than that of other display devices such as cathode ray tubes and PDPs. However, there is much room for improvement in characteristics of display devices such as brightness and lifetime.

The main reason why the light extraction efficiency of the organic light emitting display device is lower than that of other display devices is that a layer having a high refractive index such as an ITO electrode layer and a passivation film when the light emitted by the organic film is emitted above a critical angle. This is because total reflection occurs at an interface between layers having a low refractive index, such as a substrate, and is prevented from being taken out to the outside, so that only about one quarter of the light generated in the organic light emitting layer can be used.

An example of a conventional organic electroluminescent display for preventing such a decrease in light extraction rate is disclosed in Japanese Laid-Open Patent Publication No. 63-172691. The disclosed organic electroluminescent display includes a substrate having light condensation such as a protruding lens. However, such a convex lens for condensing is difficult to form on the substrate because the pixel according to the emission of the organic film is very small.

Japanese Laid-Open Patent Publication No. 62-172691 discloses an organic electroluminescent display with a first dielectric layer interposed between a transparent electrode layer and a light emitting layer and a second dielectric layer having a refractive index between the first dielectric layer and the transparent electrode on a transparent electrode side. Japanese Patent Laid-Open No. Hei 1-220394 discloses an apparatus, and an organic electroluminescent display in which a lower electrode, an insulating layer, a light emitting layer and an upper electrode are formed on a substrate, and a mirror is formed to reflect light on one surface of the light emitting layer. An apparatus is disclosed.

Since the organic light emitting display device has a very thin thickness of the light emitting layer, it is very difficult to install a mirror for reflection on the side surface, and as a result, the production cost increases.

In order to solve these problems, Japanese Laid-Open Patent Publication No. 11-283751 discloses an organic electroluminescent display device having one or more organic layers between an anode and a cathode, and includes a structure including a diffraction grating or a zone plate as a component. Is disclosed. This is to form the diffraction grating near the boundary where the refractive index is different and to extract the light of the organic film by the light scattering effect.

1 shows a bottom emission type organic electroluminescent display device of an AM (Active Matrix) driving method to which a diffraction grating structure disclosed in Japanese Patent Laid-Open No. 11-283751 is applied.

In the AM organic light emitting display device, a buffer layer 11 is formed on a transparent substrate 10, and a p-type or n-type semiconductor layer 12 arranged in a predetermined pattern on the buffer layer 11 is gated. A gate electrode layer 14 corresponding to the semiconductor layer 12, a first insulating layer 15 filling the gate electrode layer 14, and a first insulating layer 15 buried by the insulating layer 13. Drain electrodes 16 formed on the first insulating layer 15 and connected to both sides of the semiconductor layer 12 through contact holes 16a and 17a formed in the gate insulating layer 13 and 15, respectively. A thin film transistor including a source electrode 17, a first auxiliary electrode 23b connected to the source electrode 17 and formed on an upper surface of the first insulating layer 15, and opposed to the first auxiliary electrode 23b. And a driving region formed of a capacitor 23 formed of a second auxiliary electrode 23a embedded in the first insulating film 15. A first insulating layer 18 formed on the upper surface of the upper surface 15, a planarization film 19 having the openings 19a formed therein, and a bottom surface of the opening of the planarization film 19 electrically connected to the drain electrode 16. An electrode layer 20 is formed, an organic layer 21 is stacked on the first electrode layer 20, and a second electrode layer 22 is formed on the organic layer and the planarization layer to form a pixel region.

In the bottom emission type organic light emitting display device as described above, the first electrode layer 20 is made of ITO, which is a transparent conductive material, and the substrate 10, the buffer layer 11, the gate insulating layer 13, and the first, The two insulating films 15 and 18 are also made of a transparent material. In this case, since the transparent first electrode layer 20 has a high refractive index and the second insulating layer 18 has a low refractive index, the protrusions 18a are formed at the interface thereof, as shown in a partially enlarged view. It has a function of a diffraction grating to increase the light extraction efficiency.

However, when the first electrode layer 20 is formed of ITO on the upper surface of the second insulating film 18 on which the protrusions 18a are formed as described above, the step of the second insulating film 18 forming the protrusions 18a is increased. As it is reflected in the first electrode layer 20 as shown in the figure, the protrusion 20a is formed in the first electrode layer 20. Therefore, the protrusion 20a of the first electrode layer 20 also affects the organic film layer 21 deposited as a thin thin film on the upper surface of the first electrode layer 20, and thus the protrusion 21a of the shape corresponding to the organic film layer. Is formed. However, since the thickness of the organic layer 21 is very thin, the deposition thickness of the organic layer may be thin in the vicinity of the side surface of the protrusion 21a. Accordingly, as shown in the figure, the protrusion of the first electrode layer 20 ( A portion S of which the side surface and the second electrode layer 22 are short-circuited at the side portion of the protrusion portion 21a of the organic film layer 21 is generated. In the organic light emitting display device having the above structure, it is very difficult to remove the protrusions of the first electrode layer 20 due to the other layers.

In the organic light emitting display device having the above structure, since the driving region including the TFT and the capacitor is formed and the pixel region including the electrode and the organic layer is formed, the light emitted from the organic layer 21 is removed. Since the second insulating film 18, the gate insulating film 13, the buffer layer 11, the lower substrate 10, and the like must pass through the boundary between the first electrode layer 20 and the second insulating film 18, the refractive index is high. It must pass through the different layers again, and light is scattered in the process, and the light extraction efficiency gradually decreases.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide an organic light emitting display device and a method of manufacturing the same, which improve brightness by preventing scattering of light generated from an organic film in a pixel region and increasing focusing power. have.

Another object of the present invention is to provide an organic electroluminescent display device and a method of manufacturing the same, which can reduce the light loss due to scattering therein and can substantially increase the luminous efficiency.

1 is a cross-sectional view of a conventional organic light emitting display device;

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

3 and 5 are cross-sectional views showing embodiments of the light focusing portions,

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

7 to 15 illustrate a method of manufacturing the light focusing unit in the organic light emitting display device.

The present invention for achieving the above object,

A transparent substrate;

A transparent first electrode layer formed in a predetermined pattern on the substrate, an organic film formed in a predetermined pattern on the upper surface of each first electrode layer, an insulating layer formed on the upper surface of the substrate so that the organic film is exposed, and the organic film and the insulating layer A pixel forming part including a second electrode layer formed on a top surface in a predetermined pattern;

A driver including thin film transistors for switching transparent first electrodes formed on the transparent substrate;

And a light converging means provided on a path for extracting light by the organic film to prevent scattering of light generated from the organic film.

In the present invention, the light converging means may be formed of a lens unit formed on the first electrode layer or the substrate.

Another aspect of the organic electroluminescent display device of the present invention for achieving the above object is a transparent substrate,

A buffer layer formed on the substrate, a thin film transistor formed on the buffer layer, insulating layers filling the thin film transistor, a first electrode layer formed in a predetermined pattern on the upper surface of the insulating layers, and selectively applied with voltage by the thin film transistor; An insulating planarization film having an opening formed to expose the electrode layer, an organic film formed on an upper surface of the first electrode layer, and a second electrode layer formed in a predetermined pattern on the upper surface of the organic film and the planarization film;

It is characterized in that the light converging means for condensing light on the path of the light generated and extracted from the organic film is formed.

In the present invention, the light converging means includes a lens unit formed on at least one side of the insulating layer, the buffer layer, or the substrate. The lens part is formed by filling a first insulating layer having a different refractive index and being recessed in the insulating layer and a second insulating layer stacked on the recessed portion. Herein, the density of the material forming the first insulating layer in which the recess is formed is lower than the density of the material forming the second insulating layer.

The lens unit of the light focusing means is formed by forming a lens unit on at least one of the insulating layers or the substrate.

The organic electroluminescent display device of the present invention for achieving the above object is a transparent substrate, first electrode layers formed in a predetermined pattern on the substrate, and formed on the substrate, the first electrode layer to expose the first electrode layers A planarization film including a buffer layer having an opening, at least one driving unit for applying a predetermined voltage to the first electrode layer selected to be formed in the buffer layer, and a second opening portion filling the driving unit and exposing the first electrode layer And a second electrode layer formed on the organic film applied to each of the first electrode layers and the organic film exposed to the planarization film and the second opening,

The substrate is provided with a light focusing means for focusing light on a path generated and extracted from the organic film.

According to an aspect of the present invention, there is provided a method of manufacturing an organic light emitting display device, the method including forming a buffer layer on an upper surface of a transparent substrate, a second step of forming a first insulating layer on an upper surface of the buffer layer, and Applying a photoresist film on the upper surface of the first insulating layer, and exposing and developing the photoresist film, the third step for the etching pattern for forming a predetermined lens portion, and etching the first insulating layer coated with the photosensitive film of the predetermined etching pattern to the lens portion Forming a lens unit by forming a second insulating layer on an upper surface of the first insulating layer from which the photosensitive film is coated on the first surface of the first insulating layer; It is characterized by including the sixth step.

In the present invention, the third step may further include a heat treatment step of forming a convex curved surface of the surface of each pattern by heat-treating the photoresist film having the etching pattern at a high temperature, the etching in the fourth step is made of boiling angle . Herein, the density of the material forming the first insulating layer is greater than the density of the material forming the second insulating layer.

In the fourth step, the etching pattern of the first insulating layer is etched to have a concave shape having a curved surface. In the sixth step, the second insulating layer applied to the upper surface of the first insulating layer is concave. The lens unit is filled in to form a lens unit, wherein in the fourth step, the etching is performed at an equiaxed angle. Herein, the density of the material forming the first insulating layer is smaller than the density of the material forming the second insulating layer.

Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 illustrates an example of an AM-type organic light emitting display (AMOLED) as an organic light emitting display according to the present invention.

Referring to the drawings, in the organic light emitting display device, a buffer layer 111 is formed on an upper surface of the transparent substrate 100 and a pixel having a pixel on the upper surface of the buffer layer 111 and a first electrode 112 for formation thereof, respectively. The forming unit 110, the thin film transistor TFT, and the capacitor may be roughly divided into a driver 120 driving the electrodes of the pixel region.

The driver 120 includes a buffer layer 111 formed on the substrate 100 and a thin film transistor (TFT), a capacitor, and the like on the upper surface of the buffer layer 111.

The driving region 120 is a p-type or n-type semiconductor layer 122 arranged in a predetermined pattern on the upper surface of the buffer layer 111, and a first insulating layer which is a gate insulating layer filling the semiconductor layer 122. 123, a gate electrode layer 124 disposed on an upper surface of the first insulating layer 123 to correspond to the semiconductor layer 122, a second insulating layer 125 filling the second insulating layer 125, and the second insulating layer 125. ) And drain electrodes 126 connected to both sides of the semiconductor layer 122 through contact holes 126a and 127a formed in the first insulating layer 123, respectively, and formed on the second insulating layer 125. And a thin film transistor including a source electrode 127, a first auxiliary electrode 128b connected to the source electrode 127 and formed on an upper surface of the second insulating layer 125, and the first auxiliary electrode 128b. And a capacitor 128 made of a second auxiliary electrode 128a which is opposite to and is embedded in the inner insulating layer 125. A third insulating layer 129 is formed on the top surface of the second insulating layer 125 to fill the drain electrode 126 and the source electrode 127.

Here, at least one side of the first, second, and third insulating layers 123, 125, and 129, the buffer layer 111, and the substrate may emit light that is generated and extracted from the organic layer of the pixel forming unit 110, which will be described later. A light focusing unit 150 that focuses is formed.

The light converging unit 150 may include one or two layers of the first, second, and third insulating layers 123, 125, and 129, at least one side of the buffer layer 111, and the transparent substrate 100. It may be formed including a lens unit 151 formed. That is, as shown in FIG. 3, the lens unit 151 may be formed in plural in a predetermined pattern on at least one of the first, second, and third insulating layers 123, 125, and 129. As illustrated in FIG. 4, the lens unit 152 may be formed of one lens unit formed at a portion corresponding to the first electrode 112 of the pixel region 110. Herein, the density of the material forming the lens unit is preferably made of a material higher than the density of the material forming the side laminated thereto.

In another embodiment of the light converging means, a recess 153 is formed in one of the insulating layers in FIG. 5, and a layer stacked thereon is filled in the recess 153 to form a lens unit 154. It is desirable to. For example, the recess 153 may be formed in at least one of the substrate 100, the buffer layer, and the first, second, and third insulating layers 123, 125, and 129. In this case, when the recess is formed in the substrate 100, the buffer layer 111 is filled in the lens to form the lens 154, and the recess 153 is formed in the third insulating layer 129. In this case, the transparent electrode 112 is filled in the recess 153 formed in the third insulating layer 129 to form the lens unit 154. As described above, when the lens part is formed by the layer in which the concave portion 153 is formed and the layer filled therein, the refractive indices of the two layers are different from each other, and the densities of the materials forming them are different. The density of the material is preferably lower than the density of the material of the layer is not formed the density of the material forming the layer is formed. For example, it is preferable to use SiNx (refractive index 2.05) as the material of the insulating layer having a relatively high density, and SiO ₂ (refractive index 1.46) or SiOxNy (refractive index 1.6-1.88) is preferably used as the material having a low density.

Meanwhile, as illustrated in FIG. 2, the pixel forming unit 110 is formed on the upper surface of the third insulating layer 129 stacked on the transparent substrate 100 and electrically connected to the drain electrode 112. The planarization layer 140 includes a first electrode 112 and an opening 141 exposing the transparent electrode 112 on an upper surface of the third insulating layer. An organic layer 160 is formed on an upper surface of the transparent electrode 112 exposed by the opening 141 of the planarization layer 140, and a predetermined surface is formed on the upper surface of the organic layer 160 and the planarization layer 140. The second electrode 170 is formed in a pattern of. A light condenser may be provided on the transparent electrode of the pixel forming unit 110. As described above, the light converging part forms a lens part on the first electrode 112 or forms a concave part on the third insulating layer 129 corresponding to the first electrode 112 as in the above-described embodiment. ) Can be formed by being filled. In this case, since the unevenness of the organic layer 160 and the second electrode 170 is formed by the formation of the lens part formed on the first electrode 112, the external light reflection from the second electrode 170 can be reduced.

6 illustrates another embodiment of an organic light emitting display device according to the present invention. The organic light emitting display according to the present invention is roughly divided into a driver 120 including a thin film transistor and a capacitor and a pixel forming unit 180 driven by the driver 120. Since it is substantially the same as, only the differences will be described.

Referring to the drawings, the pixel region 180 of the organic light emitting display device according to the present invention includes the buffer layer 111, the first, second, and third insulating layers 123, 125, 129, and the planarization layer 140. An opening 182 is formed in the first electrode 181 to expose the first electrode 181, and an organic film 183 is formed on an upper surface of the first electrode 181 exposed by the opening 182. The second electrode 170 of the predetermined pattern is formed on the top surface of the 183 and the top surface of the planarization film 140. The drain electrode 126 is electrically connected to the first electrode 181 through the first, second, and third insulating layers 123, 125, 129, and the buffer layer 111. A light concentrator is installed on at least one side of the first electrode 181 and the substrate 100. The light concentrator 150 includes a lens unit formed on the substrate 100 or a concave unit formed on the transparent substrate. In this case, the transparent electrode 181 may be embedded.

In the organic light emitting display according to the present invention configured as described above, a predetermined voltage is applied to the first electrode 112 by the driver and the thin film transistor selected as shown in FIGS. 2 and 6, and a second electrode. When a voltage is applied to the 170, holes injected from the first electrode 112 are moved to the light emitting layer via the hole transport layer forming the organic layer, and electrons are transferred from the second electrode electrode 170 to the electron transport layer. Is injected into the light emitting layer. Electrons and holes recombine in this light emitting layer to generate excitons, and as the excitons change from the excited state to the ground state, the fluorescent molecules of the light emitting layer 73 emit light. Light generated at this time is extracted through the first electrode 112, the first, second, and third insulating layers 123, 125, 129, the buffer layer 111, and the transparent substrate 100. In this process, since the light converging unit 150 is installed on the light extraction path, the light collected can be collected in one place to maximize the efficiency of luminance. That is, at least one side of the first, second, and third insulating layers 123, 125, and 129, the transparent substrate 100, and the buffer layer 111, which are the light extraction paths, or the boundary layer stacked on the lens unit 151 (lens). A) is formed to focus light. In this case, when the convex lens portion is formed on the first, second, and third insulating layers 123, 125, 129, the transparent substrate 100, and the buffer layer 111, the density of the material forming the layer forming the convex lens portion is stacked thereon. Since it is formed higher than the density of the layer, the effect of the convex lens can be obtained. When the first, second, and third insulating layers 123, 125, 129, the transparent substrate 100, and the buffer layer 111 are formed with recesses and the stacked layers are filled, the convex portions form a layer. Since the density of the material is formed lower than the material density of the layer to be laminated, the effect of the same convex lens can be expected. Therefore, the focusing efficiency of the light irradiated from the organic film can be increased to increase the focusing efficiency.

7 through 11 illustrate one embodiment of a method of forming a lens unit, which is a light focusing unit, in the organic light emitting display device according to the present invention configured as described above. In this embodiment, the lens unit is formed on the first, second, and third insulating layers 123, 125, and 129, but is not limited thereto.

A first step of forming a buffer layer 111 on the upper surface of the transparent substrate 100 (see FIG. 7), a second step of forming a first insulating layer 123 on an upper surface of the buffer layer, and the first insulating layer And a third step (see FIG. 8) for the etching pattern 201 for forming a predetermined lens by applying a photoresist film to the upper surface of the photoresist and exposing and developing the same. The method may further include a heat treatment step (see FIG. 9) for forming the outer surface of each pattern into a curved surface by heat-treating the photoresist film in the process of forming the etching pattern 201 at a high temperature. The temperature of the heat treatment is preferably to soften the photosensitive film so that the outer peripheral surface is curved.

A fourth step (see FIG. 10) is performed to etch the curved surface by etching the first insulating layer coated with the photoresist of the predetermined pattern. The etching may be performed by using an etching pattern 201 having an outer circumferential surface to be curved. As shown in FIG. 11, an isotropic angle of etching after forming a simple pattern without performing heat treatment in the process of forming the etching pattern may be performed.

A fifth step (see FIG. 12) is performed to remove the photoresist film coated on the upper surface of the first insulating layer. In the fifth step, in the case of the boiling angle, as shown in FIG. 10, the convex lens part is formed in the first insulating layer, and in the case of the equal angle, the first insulating layer 123 as shown in FIG. 13. Is formed in the recess 153.

As described above, when the photoresist film is removed from the upper surface of the first insulating layer 123, the second insulating layer 125 is formed on the upper surface of the first insulating layer 123. At this time, the convex lens formed by the boiling angle is embedded in the second insulating layer to form a lens portion as shown in FIG. 14. In the case of the equal angle, the second insulating layer is formed in the concave portion as shown in FIG. 15. Is filled to form the lens part. At this time, the density of the material forming the first and second insulating layers is mentioned in the above configuration and will not be described again.

In the organic electroluminescent device of the present invention and the method of manufacturing the same, the light converging portion is formed on the optical path generated from the organic film, thereby preventing light scattering and improving the light concentrating efficiency. Can increase the luminance. In addition, when the lens unit is formed on the transparent electrode layer, the surface area on which the organic layer is applied may be widened, and the reflection efficiency by the cathode electrode layer may be lowered by forming a bend on the cathode electrode layer applied on the organic layer.

Although the present invention has been described with reference to one embodiment shown in the drawings, this is merely exemplary and one of ordinary skill in the art will understand that various modifications and variations are possible. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Claims (7)

A transparent substrate; A transparent first electrode layer formed in a predetermined pattern on the substrate, an organic film formed in a predetermined pattern on the upper surface of each first electrode layer, an insulating layer formed on the upper surface of the substrate so that the organic film is exposed, and the organic film and the insulating layer A pixel forming part including a second electrode layer formed on a top surface in a predetermined pattern; A driving unit formed on the transparent substrate and including thin film transistors for switching transparent electrodes; It has a convex or concave lens portion for focusing the light generated from the organic film on the optical path taken out of the light by the organic film, the density of the material constituting the lens portion is higher or lower than the density of the adjacent material to the density difference And an optical focusing means for focusing light by means of an organic light emitting display. A first step of forming a buffer layer on an upper surface of the transparent substrate, A second step of forming a first insulating layer on an upper surface of the buffer layer; A third step of applying a photoresist film on the upper surface of the first insulating layer, exposing and developing the photoresist film, and etching patterns for forming a predetermined lens; A fourth step of etching the curved surface by etching the first insulating layer coated with the photosensitive film of the predetermined pattern, a fifth step of removing the photosensitive film applied to the upper surface of the first insulating layer, and a first step of removing the photosensitive film And a sixth step of forming a light converging portion by forming a second insulating layer on an upper surface of the insulating layer. The method of claim 2, The third step may further include a heat treatment step of forming the surface of each pattern into a curved surface by heat-treating the photosensitive film having the etching pattern at a high temperature, the etching in the fourth step is characterized in that the boiling angle Method of manufacturing an organic electroluminescent display. The method of claim 2, wherein the density of the material forming the first insulating layer is greater than the density of the material forming the second insulating layer. The method of claim 2, In the fourth step, the etching pattern of the first insulating layer is etched to have a concave shape having a curved surface, and in the sixth step, a second insulating layer is formed on the top surface of the first insulating layer to form the concave. And filling the portion with the material of the second insulating layer to form the lens portion. The method of claim 5, The density of the material forming the first insulating layer is less than the density of the material forming the second insulating layer. The method of claim 5, The etching in the fourth step is a method of manufacturing an organic electroluminescent display device, characterized in that the equi-corrosion angle.