KR102184939B1 - Organic Light Emitting Diode Display And Method For Manufacturing The Same - Google Patents

Abstract

The present invention relates to an organic light emitting diode display using a micro-cavity structure in a specific sub-pixel and a method of manufacturing the same. In the method of manufacturing an organic light emitting diode display according to the present invention, a transparent conductive material is applied on a substrate to a first thickness and patterned with a first photoresist, thereby forming a transparent anode electrode in which the first photoresist is stacked on a first sub-pixel. Forming; Applying a translucent conductive material to a second thickness on the substrate on which the transparent anode electrode and the first photoresist are stacked, patterning with a second photoresist, and forming a translucent anode electrode on a second sub-pixel; Forming an organic light emitting layer on the surface of the substrate on which the transparent anode electrode and the translucent anode electrode are formed; And forming a cathode electrode using a reflective conductive material on the organic emission layer.

Description

Organic Light Emitting Diode Display And Method For Manufacturing The Same}

The present invention relates to an organic light emitting diode display using a micro-cavity structure in a specific sub-pixel and a method of manufacturing the same. In particular, in the present invention, in using an organic layer emitting white light and a color filter, a micro-cavity structure is selectively applied to any one sub-pixel whose luminance efficiency is lower than that of other sub-pixels. It relates to an organic light emitting diode display device compensating for luminance efficiency and a method of manufacturing the same.

Recently, various flat panel display devices capable of reducing the weight and volume, which are the disadvantages of a cathode ray tube, have been developed. Such flat panel displays include a liquid crystal display (LCD), a field emission display (FED), a plasma display panel (PDP), and an electroluminescence device (EL). have.

Electroluminescent devices are roughly classified into inorganic electroluminescent devices and organic light emitting diode devices according to the material of the light emitting layer, and are self-luminous devices that emit light by themselves. They have a fast response speed and great luminous efficiency, luminance, and viewing angle. In particular, the organic light emitting diode display is a self-luminous display device and does not require a backlight such as a liquid crystal display device, so that it is easier to reduce weight and thickness. In addition, it can be manufactured by simplifying the process. In addition, the organic light emitting diode display has many advantages such as low voltage driving, high luminous efficiency, and a wide viewing angle, and thus is attracting attention as a next-generation display device.

The organic light emitting diode display includes an anode electrode, an organic light emitting layer, and a cathode electrode sequentially stacked on a substrate. Holes provided from the anode electrode and electrons provided from the cathode electrode are recombined in the organic light emitting layer to form excitons. This exciter emits light as it falls from an unstable high energy level to a stable low energy level. At this time, the light passes through any one of the anode and the cathode and the substrate to provide an image to the user.

1 is a schematic diagram showing the structure of a general organic light emitting diode. The organic light emitting diode includes an organic electroluminescent compound layer that emits light as shown in FIG. 1, and a cathode electrode and an anode electrode facing each other with the organic electroluminescent compound layer therebetween. The organic electroluminescent compound layer includes a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer. layer, EIL).

In the organic light-emitting diode, excitons are formed during the excitation process when holes and electrons injected into the anode and cathode electrodes recombine in the emission layer EML and emit light due to energy from the excitons. The organic light emitting diode display device displays an image by electrically controlling the amount of light emitted from the emission layer EML of the organic light emitting diode as shown in FIG. 1.

In the organic light emitting diode display (OLEDD) using the characteristics of the organic light emitting diode, which is an electroluminescent device, a passive matrix type organic light emitting diode display (PMOLED) and an active matrix It is roughly classified as an Active Matrix type Organic Light Emitting Diode display (AMOLED).

An active matrix type organic light emitting diode display (AMOLED) displays an image by controlling the current flowing through the organic light emitting diode using a thin film transistor ("TFT").

2 is an example of an equivalent circuit diagram showing the structure of one pixel in a general active matrix type organic light emitting diode display (or AMOLED). 3 is a plan view showing a structure of one pixel in an AMOLED according to the prior art. FIG. 4 is a cross-sectional view showing the structure of an AMOLED according to the prior art cut along the perforated line I-I' in FIG.

2 and 3, an active matrix organic light emitting diode display according to the prior art includes a switching thin film transistor (ST), a driving TFT (DT) connected to the switching TFT, and an organic light emitting diode (OLED) connected to the driving TFT (DT). ). The scan line SL, the data line DL, and the driving current line VDD are disposed on the substrate SUB to define a pixel area. An organic light-emitting diode (OLED) is formed in the pixel area to define a light emitting area.

The switching TFT ST is formed at a portion where the scan wiring SL and the data wiring DL intersect. The switching TFT (ST) functions to select a pixel. The switching TFT (ST) includes a gate electrode (SG) branching from the scan wiring (SL), a semiconductor layer (SA), a source electrode (SS), and a drain electrode (SD). And the driving TFT DT serves to drive the organic light emitting diode OLE of the pixel selected by the switching TFT ST. The driving TFT DT includes a gate electrode DG connected to the drain electrode SD of the switching TFT ST, a semiconductor layer DA, a source electrode DS connected to the driving current line VDD, and a drain electrode ( DD). The drain electrode DD of the driving TFT DT is connected to the anode electrode ANO of the organic light emitting diode OLE. The organic light emitting layer OL is interposed between the anode electrode ANO and the cathode electrode CAT. The cathode electrode CAT is connected to the ground voltage VSS. An auxiliary capacitance Cst between the gate electrode DG of the driving TFT DT and the driving current line VDD or between the gate electrode DG of the driving TFT DT and the drain electrode DD of the driving TFT DT Is placed.

Referring to FIG. 4 to examine in more detail, the switching TFT ST and the gate electrodes SG and DG of the driving TFT DT are formed on a substrate SUB of an active matrix organic light emitting diode display. In addition, the gate insulating film GI is covering the gate electrodes SG and DG. Semiconductor layers SA and DA are formed on a part of the gate insulating film GI overlapping the gate electrodes SG and DG. Source electrodes SS and DS and drain electrodes SD and DD are formed on the semiconductor layers SA and DA at regular intervals to face each other. The drain electrode SD of the switching TFT ST contacts the gate electrode DG of the driving TFT DT through a contact hole formed in the gate insulating film GI. A protective film PAS covering the switching TFT ST and the driving TFT DT having such a structure is formed on the entire surface.

In this way, the substrate on which the thin film transistors ST and DT are formed is formed with various components, so that the surface is not flat and has many steps. The organic light emitting layer OL must be formed on a flat surface so that light emission can be uniformly and uniformly emitted. Accordingly, a planarization film or an overcoat layer OC is formed on the entire surface of the substrate for the purpose of flattening the surface of the substrate.

In addition, the anode electrode ANO of the organic light emitting diode OLE is formed on the overcoat layer OC. Here, the anode electrode ANO is connected to the drain electrode DD of the driving TFT DT through the pixel contact hole PH formed in the overcoat layer OC and the passivation layer PAS.

On the substrate on which the anode electrode ANO is formed, a bank BN is formed on a region in which the switching TFT (ST), the driving TFT (DT), and various wirings (DL, SL, VDD) are formed to define a light emitting region. The anode electrode ANO exposed by the bank BN becomes a light emitting area. An organic light emitting layer OL is formed on the anode electrode ANO exposed by the bank BN. A cathode electrode layer CAT is formed on the organic light emitting layer OL.

In the case of the example shown in FIG. 4, a bottom emission type and full-color organic light emitting diode display is shown. In this case, a color filter CF may be further included between the overcoat layer OC and the passivation layer PAS, and the anode electrode ANO may include a transparent conductive material. In this case, the organic light-emitting layer OL may be made of an organic material that expresses white light. In addition, the organic emission layer OL and the cathode electrode CAT may be formed over the entire surface of the substrate.

In order to reproduce the actual natural color as possible in such an organic light emitting diode display, the color reproduction efficiency value of the color emitted from each pixel is important. However, until now, organic light emitting diode displays have been developed with more emphasis on driving voltage or manufacturing process than color reproduction efficiency. In other words, technology has been developed with a focus on productivity, taking into account the decrease in color reproduction efficiency implemented by the organic light emitting diode display to some extent.

However, at the present time when the production technology for an organic light emitting diode display device has reached a considerable level, producing a display device having excellent display quality becomes a more important problem. In order to improve display quality in an organic light emitting diode display, it is most important to keep the luminous efficiencies reproduced for each pixel uniform with each other.

In an organic light emitting diode display of an active matrix type, one unit pixel includes three or four sub-pixels. Each sub-pixel represents basic colors such as red, green, and blue, and they are combined in one unit pixel to express a specific color. In the case of an organic light emitting diode display, light is expressed in the organic light emitting layer, and a predetermined color is expressed in each sub-pixel through a color filter.

In an organic light emitting diode display, when the luminous efficiency of a sub-pixel representing a specific color is significantly lower than that of other sub-pixels, depending on the material of the organic light-emitting layer that emits light, it is difficult to correctly implement the overall color. In order to solve this problem, in selecting the organic light-emitting material constituting the organic light-emitting layer, it is most preferable to select a material having substantially the same light-emitting efficiency in all color ranges. However, this is directly related to physical properties, and is a method that is almost impossible to implement and requires a lot of cost and difficulty. Therefore, there is an urgent need for an efficient method to solve this problem.

An object of the present invention is an invention conceived to solve the problems of the prior art. When an organic light emitting layer expressing white light is commonly applied to all sub-pixels and used, it is to compensate for the lowered luminous efficiency in a specific sub-pixel For this purpose, it is an object to provide an organic light emitting diode display and a method of manufacturing the same, in which a micro-cavity structure is selectively applied only to specific sub-pixels.

In order to achieve the above object, an organic light emitting diode display according to the present invention includes: a substrate in which unit pixels including red, green, blue, and white sub-pixels are arranged in a matrix manner; A translucent anode electrode having a first thickness formed in a first sub-pixel selected from among the red, green, and blue sub-pixels; A transparent anode electrode having a second thickness formed in the remaining sub-pixels except for the first sub-pixel; An organic emission layer commonly applied to all the sub-pixels; And a cathode electrode commonly applied to all of the sub-pixels on the organic emission layer, and emit light from the cathode electrode toward the translucent anode electrode and from the cathode electrode toward the transparent anode electrode.

The translucent anode electrode includes a first transparent conductive layer, a semi-transparent metal layer, and a second transparent conductive layer, the transparent anode electrode includes a transparent conductive layer, and the first thickness of the translucent anode electrode is the transparent It is thinner than the second thickness of the anode electrode.

In addition, in the method of manufacturing an organic light emitting diode display according to the present invention, a transparent anode in which the first photoresist is stacked on a first sub-pixel by applying a transparent conductive material to a first thickness on a substrate and patterning with a first photoresist. Forming an electrode; Applying a translucent conductive material to a second thickness on the substrate on which the transparent anode electrode and the first photoresist are stacked, patterning with a second photoresist, and forming a translucent anode electrode on a second sub-pixel; Forming an organic light emitting layer on the surface of the substrate on which the transparent anode electrode and the translucent anode electrode are formed; And forming a cathode electrode using a reflective conductive material on the organic emission layer.

The forming of the transparent anode electrode and the forming of the translucent anode electrode may include: applying the transparent conductive material; Applying the first photoresist on the transparent conductive material; Patterning the first photoresist; Forming the transparent anode electrode by etching the transparent conductive material using the pattern of the first photoresist as a mask; Applying the transflective conductive material while leaving the pattern of the first photoresist on the transparent anode electrode; Applying the second photoresist over the transflective conductive material; Patterning the second photoresist; Forming the translucent anode electrode by etching the translucent conductive material using the pattern of the second photoresist as a mask; And simultaneously removing the first photoresist remaining on the transparent anode electrode and the second photoresist remaining on the translucent anode electrode.

The step of applying the transflective conductive material may include applying a first transparent conductive layer; Applying a transflective metal layer on the first transparent conductive layer; And applying a second transparent conductive layer thinner than the first transparent conductive layer on the transflective metal layer.

The translucent anode electrode is formed in the second sub-pixel selected from red, green, and blue sub-pixels, and the transparent anode electrode is formed in all other sub-pixels except for the second sub-pixel.

The present invention provides an organic light emitting diode display device in which a micro-cavity structure is selectively applied only to specific sub-pixels whose luminous efficiency is significantly lowered. Therefore, compared to applying a micro-cavity structure to all sub-pixels, the design is easy and the structure is simple. In addition, it has the advantage that the manufacturing process is not complicated. In particular, by using the photoresist without removing it, anode electrode layers having different thicknesses can be formed without increasing the number of mask steps.

1 is a schematic diagram showing a general organic light emitting diode device.
2 is an equivalent circuit diagram showing the structure of one pixel in a general active matrix type organic light emitting diode display (AMOLED).
3 is a plan view showing a structure of one pixel in an organic light emitting diode display of an active matrix type according to the prior art.
FIG. 4 is a cross-sectional view showing the structure of an organic light emitting diode display of an active matrix type according to the prior art, cut along the perforated line I-I' in FIG. 3;
5 is a plan view showing a structure of a unit pixel including four sub-pixels in an organic light emitting diode display according to the present invention.
FIG. 6 is a cross-sectional view showing a structure of a unit pixel including four sub-pixels in the organic light emitting diode display according to the present invention, taken along a cut line II-II' in FIG.
7A to 7F are cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to the first exemplary embodiment of the present invention, cut by a cut line II-II' in FIG. 5.
8A to 8F are cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to a second exemplary embodiment of the present invention, cut by a cut line II-II' in FIG. 5.

Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. The same reference numerals throughout the specification mean substantially the same constituent elements. In the following description, when it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the subject matter of the present invention, a detailed description thereof will be omitted.

In the present invention, an organic light-emitting diode which is mainly used at present is used, but has a structure that compensates to approximate the luminous efficiency of other sub-pixels by giving structural characteristics to a specific sub-pixel whose luminous efficiency is significantly lowered. A display device and a method of manufacturing the same are provided.

The structural features of the organic light emitting diode display according to the present invention will be described with reference to FIGS. 5 and 6. 5 is a plan view illustrating a structure of a unit pixel including four sub-pixels in an organic light emitting diode display according to the present invention. 6 is a cross-sectional view illustrating a structure of a unit pixel including four sub-pixels in the organic light-emitting diode display according to the present invention, taken along a cut line II-II' in FIG. 5.

In the organic light emitting diode display according to the present invention, one unit pixel includes four sub-pixels. For example, it may include sub-pixels representing colors of red (R; red), white (W; white), green (G; green), and blue (B; blue). In order to represent the color designated in each pixel, the organic light emitting layer itself can be configured to express its own color. Further, the organic light emitting layer may be configured to express white light and selectively express a desired color by using a color filter. In the present invention, the latter case will be mainly described.

Referring to FIG. 5, the basic configuration of the organic light emitting diode display according to the present invention is almost the same as that of the prior art. Therefore, redundant descriptions are omitted. In addition, the same components will be described with reference to the same reference numerals. The organic light emitting diode display according to the present invention is a bottom emission type that emits light in the direction of the substrate SUB to display an image. Accordingly, after forming the thin film transistors ST and DT on the substrate SUB, color filters CF corresponding to the opening regions of each pixel are formed. A protective layer PAS is covered on the thin film transistors ST and DT. In addition, color filters CF are formed on the passivation layer PAS to correspond to the opening area.

For example, a red (R) color filter (CF) is formed in a red sub-pixel, a green (G) color filter (CF) is formed in a green sub-pixel, and a blue (B) color filter (CF) is formed in a blue sub-pixel. . In addition, a special color filter may not be formed in the white sub-pixel. However, it is preferable to form a white (W) color filter CF with a transparent resin so that the heights of the sub-pixels on which other color filters are formed are equal.

In the present invention, the organic light emitting layer OL is made of a material that expresses white light. Since it is a bottom-emission type, it is preferable that the anode electrode ANO connected to the drain electrode DD of the driving thin film transistor DT includes a material such as indium-tin-oxide (ITO), which is a transparent conductive material. Do. In addition, it is preferable that the cathode electrode CAT includes a metallic material having high reflectivity.

In addition, the present invention applies a microcavity structure to the specific sub-pixel when the luminous efficiency (or color reproducibility) decreases in a specific sub-pixel compared to other sub-pixels, thereby compensating the luminous efficiency. It features. For example, if the luminous efficiency of the red sub-pixel in FIG. 6 is significantly lowered, the thickness of the organic light-emitting layer OL is different from the thickness of the organic light-emitting layer OL of other sub-pixels to give a micro-cavity effect. have. As a result, it is possible to implement a color implemented in the entire unit pixel as a desired color by compensating for the luminous efficiency in the sub-pixel having significantly lower luminous efficiency.

To this end, the organic light emitting diode display according to the present invention includes a first sub-pixel having a micro-cavity structure and a second sub-pixel to which the micro-cavity structure is not applied. The first sub-pixel having a micro-cavity structure includes a micro-cavity organic light-emitting diode MOLE in which a semi-transparent anode electrode HANA including a semi-transparent conductive material, an organic light-emitting layer OL, and a cathode electrode CAT are stacked. . Meanwhile, the second sub-pixel without a micro-cavity structure includes an organic light emitting diode (OLE) in which a transparent anode electrode (ANO) including a transparent conductive material, an organic light emitting layer (OL), and a cathode electrode (CAT) are stacked. do.

It will be described in more detail with reference to FIG. 6. In FIG. 6, a case where a micro-cavity structure is applied to a red sub-pixel and a micro-cavity structure is not applied to other sub-pixels (white, green, and blue sub-pixels) will be described. In sub-pixels to which the micro-cavity structure is not applied, a transparent anode electrode ANO, a white organic light emitting layer OL, and a reflective cathode electrode CAT are stacked to form an organic light emitting diode OLE. Here, the transparent anode electrode ANO is formed of a transparent conductive material such as ITO to a thickness of about 1,000 to 1500 Å. In addition, the reflective cathode electrode CAT is preferably formed of a metal material having high reflectivity to a thickness of about 1,000 to 2,000 Å.

Meanwhile, a micro-cavity structure is selectively applied only to the red sub-pixel. In the organic light emitting diode display according to the present invention, the organic light emitting layer OL is commonly applied over the entire surface of the substrate. That is, it is commonly applied to both sub-pixels to which the micro-cavity is applied and sub-pixels that do not. That is, the thickness of the organic light emitting layer OL has substantially the same thickness over the entire substrate SUB. Therefore, in order to selectively apply the micro-cavity effect to only the red sub-pixels, the thickness of the anode electrode of the red sub-pixel must be formed different from that of the other sub-pixels. In addition, in order to further amplify the microcavity effect, it is preferable to form the anode electrode of the red sub-pixel to be semi-transmissive.

For example, in a red sub-pixel to which a micro-cavity structure is applied, a translucent anode electrode (HANO), a white organic light-emitting layer (OL), and a reflective cathode electrode (CAT) are stacked to form a micro-cavity organic light-emitting diode (MOLE). . Here, the translucent anode electrode HAO may have a structure in which three conductive layers are stacked, such as a first transparent conductive layer ITO1 / a semi-transmissive layer Ag / a second transparent conductive layer ITO2. For example, an indium-tin oxide layer having a thickness of 600 Å, a metal thin film layer including silver (Ag) having a thickness of 120 Å, and an indium-tin oxide layer having a thickness of 100 Å are stacked to form a translucent anode (HANO) Can be formed. In addition, it is preferable that the reflective cathode electrode CAT is applied in common over the entire substrate SUB, similar to the white organic light emitting layer OL.

As described above, the translucent anode electrode HAO of the red sub-pixel to which the micro-cavity is applied may have a thickness thinner than that of the transparent anode electrode ANO of other sub-pixels. It is preferable that this degree of thinness is designed so that the red wavelength can be amplified in the red sub-pixel. More specifically, it is preferable to design the thickness of each layer of the translucent anode electrode HAO so that the distance between the reflective cathode electrode CAT and the transflective layer Ag is a multiple of the red wavelength.

In this configuration, in the red sub-pixel to which the micro-cavity is applied, an effect of amplifying for a specific frequency (here, the red frequency) between the translucent anode electrode HANA and the cathode electrode CAT can be obtained. Accordingly, the luminous efficiency of the other sub-pixels and the luminous efficiency of the red sub-pixel can be matched to almost the same level.

In the example described above, a case in which the anode electrode of the red sub-pixel to which the micro-cavity structure is applied is formed to be thinner than that of the other sub-pixel has been described. However, in some cases, the thickness of the anode electrode of the red sub-pixel may be thicker than that of the other sub-pixel. In addition, the micro-cavity structure may be applied to any one of green and blue sub-pixels instead of red sub-pixels. In the white sub-pixel, since light emitted from the organic light emitting layer OL is used as it is, there is no need to apply a micro-cavity structure. Accordingly, by selectively applying a micro-cavity structure to any one of the red, green, and blue sub-pixels having low luminous efficiency, the overall luminous efficiency can be uniformly adjusted.

Hereinafter, a method of manufacturing an organic light emitting diode display according to the present invention will be described in detail with reference to the drawings. The following two methods may be considered as a method of manufacturing an organic light emitting diode display according to the present invention. However, it is not limited to these two methods, and various modifications can be made by the relevant engineer by applying them.

First, a first embodiment of the present invention will be described with reference to FIGS. 7A to 7F. 7A to 7F are cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to the first exemplary embodiment of the present invention, cut by a cut line II-II' in FIG. 5.

For convenience, a detailed description of the process of forming the thin film transistors ST and DT that does not include the main contents of the present invention will be omitted.

Sub-pixels arranged in a matrix manner are defined on the substrate SUB, and thin film transistors ST and DT are formed in each of the sub-pixels. A passivation layer PAS is applied on the drain electrode DD of the driving thin film transistor DT. A red (R) color filter CF is formed in the red sub-pixel area on the passivation layer PAS. In addition, a white (W) color filter CF is formed in the white sub-pixel area. In the first embodiment, an example in which a micro-cavity structure is selectively applied only to red sub-pixels will be described. Accordingly, the sub-pixels to which the micro-cavity structure is not applied will be described as a white sub-pixel.

A planarization layer or an overcoat layer OC is applied on the substrate SUB on which the color filters CF are formed. In addition, a pixel contact hole PH exposing a portion of the drain electrode DD of the driving thin film transistor DT is formed by removing portions of the overcoat layer OC and the passivation layer PAS. The first transparent conductive layer ITO1 is applied to a thickness of about 600 Å on the entire surface of the substrate SUB on which the pixel contact hole PH is formed. Then, a semi-transmissive layer (Ag) is applied to a thickness of about 120 Å with a metal material such as silver (Ag). Subsequently, the second transparent conductive layer ITO2 is applied to a thickness of about 100 Å. After that, a first photoresist PR1 is applied on the second transparent conductive layer ITO2. The first photoresist PR1 is patterned by a first mask process. Here, it is preferable that the patterned first photoresist PR1 corresponds to the shape of the translucent anode electrode HAO. (Fig. 7a)

The first transparent conductive layer ITO1, the semitransmissive layer Ag, and the second transparent conductive layer ITO2 are simultaneously patterned in the shape of the first photoresist PR1 to form a semitransparent anode electrode HAO. It is preferable to form the translucent anode electrode HAO in the red sub-pixel to which the micro-cavity structure is applied. That is, it is preferable to be connected to the drain electrode DD of the driving thin film transistor DT allocated to the red sub-pixel to which the micro-cavity structure is applied.

Thereafter, silicon oxide is applied over the entire surface of the substrate SUB and patterned by a second mask process to form a protective layer CAP covering the translucent anode electrode HAO. (Fig. 7b)

A transparent conductive layer ITO is applied to a thickness of about 1200 Å on the entire surface of the substrate SUB on which the protective layer CAP is formed. After that, a second photoresist PR2 is applied on the transparent conductive layer ITO. The second photoresist PR2 is patterned by a third mask process. Here, it is preferable that the patterned second photoresist PR2 correspond to the shape of the transparent anode electrode ANO to be formed in the sub-pixels to which the micro-cavity structure is not applied. (Fig. 7c)

The transparent conductive layer ITO is patterned in the shape of the second photoresist PR2 to form a transparent anode electrode ANO. The transparent anode electrode ANO is preferably formed in a white sub-pixel (including other sub-pixels) to which a micro-cavity structure is not applied. That is, it is preferable to be connected to the drain electrode DD of the driving thin film transistor DT allocated to the white, green, and blue sub-pixels to which the micro-cavity structure is not applied. (Fig. 7d)

A bank BA defining an opening area of each sub-pixel is formed on the substrate SUB on which the translucent anode electrode HAO and the transparent anode electrode ANO are formed. The area exposed by the bank BA is defined as an opening area emitting light. (Fig. 7e)

An organic light emitting layer OL expressing white light is applied on the entire surface of the substrate SUB on which the bank BA is formed. Subsequently, a cathode electrode CAT including a metallic material having high reflectivity is applied. Accordingly, in the (red) sub-pixel to which the micro-cavity is applied, the micro-cavity organic light-emitting diode MOLE in which the translucent anode electrode HANA, the organic light-emitting layer OL, and the cathode electrode CAT are stacked is formed. On the other hand, in general sub-pixels to which a micro-cavity is not applied, an organic light emitting diode OLE in which a transparent anode electrode ANO, an organic light emitting layer OL, and a cathode electrode CAT are stacked is formed. (Fig. 7f)

Here, the thickness of the translucent anode electrode HANA of the (red) sub-pixel to which the micro-cavity is applied is thinner than that of the transparent anode electrode ANO of the general sub-pixel. In particular, the separation distance between the translucent anode electrode HANA and the cathode electrode CAT may be set to satisfy a condition in which light of a red wavelength is amplified. As a result, it is possible to compensate for the luminous efficiency of the red) sub-pixel to which the micro-cavity is applied, and thereby maintain the luminous efficiency of all sub-pixels constant.

In the first embodiment of the present invention, a case where the translucent anode electrode HAO of the (red) sub-pixel to which the micro-cavity structure is applied is first formed, and then the transparent anode electrodes ANO of the general sub-pixels are formed has been described. . However, in some cases, after first forming the transparent anode electrodes ANO of the general sub-pixels, the semi-transparent anode electrode HAO of the (red) sub-pixel to which the micro-cavity structure is applied may be formed. Which one is to be formed first can be selected as the most desirable one by the manufacturer in consideration of manufacturing equipment and/or process conditions.

Next, a second embodiment of the present invention will be described with reference to FIGS. 8A to 8F. 8A to 8F are cross-sectional views illustrating a method of manufacturing an organic light emitting diode display according to a second exemplary embodiment of the present invention, cut by a cut line II-II' in FIG. 5.

In the present invention, in the process of forming the anode, a transparent anode electrode ANO of general sub-pixels and a translucent anode electrode HAO of a sub-pixel to which a micro-cavity is applied are separately formed. Accordingly, it is necessary to form a protective layer CAP to protect the first transparent anode electrode ANO from being damaged in the process of forming the translucent anode HAO which is a subsequent patterning process. This causes an increase in the number of mask processes. In the second embodiment, a method of manufacturing without increasing the number of mask processes is provided. In particular, in the second embodiment of the present invention, after first forming the transparent anode electrodes (ANOs) of general sub-pixels, the case of forming the translucent anode electrode (HANO) of the (red) sub-pixel to which the micro-cavity structure is applied is an example. Explain.

Sub-pixels arranged in a matrix manner are defined on the substrate SUB, and thin film transistors ST and DT are formed in each of the sub-pixels. A passivation layer PAS is applied on the drain electrode DD of the driving thin film transistor DT. A red (R) color filter CF is formed in the red sub-pixel area on the passivation layer PAS. In addition, a white (W) color filter CF is formed in the white sub-pixel area. Also in the second embodiment, as in the first embodiment, for convenience, an example in which the micro-cavity structure is selectively applied only to the red sub-pixel will be described. Accordingly, the sub-pixels to which the micro-cavity structure is not applied will be described as a white sub-pixel.

A planarization layer or an overcoat layer OC is applied on the substrate SUB on which the color filters CF are formed. In addition, a pixel contact hole PH exposing a portion of the drain electrode DD of the driving thin film transistor DT is formed by removing portions of the overcoat layer OC and the passivation layer PAS. A transparent conductive layer ITO is applied to a thickness of about 1200 Å on the entire surface of the substrate SUB on which the pixel contact hole PH is formed. Thereafter, a first photoresist PR1 is applied on the transparent conductive layer ITO. The first photoresist PR1 is patterned by a first mask process. Here, it is preferable that the patterned first photoresist PR1 corresponds to the shape of the transparent anode electrode ANO. (Fig. 8a)

The transparent conductive layer ITO is patterned in the shape of the first photoresist PR1 to form a transparent anode electrode ANO. The transparent anode electrode ANO is preferably formed in a white sub-pixel (including green and blue sub-pixels) to which a micro-cavity structure is not applied. That is, it is preferable to be connected to the drain electrode DD of the driving thin film transistor DT allocated to the white, green, and blue sub-pixels to which the micro-cavity structure is not applied.

After patterning the transparent anode electrode ANO, the first photoresist PR1 is not removed and left as it is. Mainly, when patterning is performed by wet etching, the transparent anode electrode ANO may have an under-cut shape from the bottom of the first photoresist PR1 to the inside. (Fig. 8b)

With the first photoresist PR1 remaining on the transparent anode electrode ANO, the first transparent conductive layer ITO1 is applied to a thickness of about 600 Å on the entire surface of the substrate SUB. Then, a semi-transmissive layer (Ag) is applied to a thickness of about 120 Å with a metal material such as silver (Ag). Subsequently, the second transparent conductive layer ITO2 is applied to a thickness of about 100 Å. Thereafter, a second photoresist PR2 is applied on the second transparent conductive layer ITO2. The second photoresist PR2 is patterned by a second mask process. Here, it is preferable that the patterned second photoresist PR2 corresponds to the shape of the translucent anode electrode HAO to be formed in the (red) sub-pixel to which the micro-cavity structure is applied. (Fig. 8c)

In the shape of the patterned second photoresist PR2, the first transparent conductive layer ITO1, the transflective layer Ag, and the second transparent conductive layer ITO2 are simultaneously patterned to form a translucent anode electrode HANA. do. It is preferable to form the translucent anode electrode HAO in the red sub-pixel to which the micro-cavity structure is applied. That is, it is preferable to be connected to the drain electrode DD of the driving thin film transistor DT allocated to the red sub-pixel to which the micro-cavity structure is applied. Both the second photoresist PR2 remaining on the translucent anode electrode HAO and the first photoresist PR1 remaining on the transparent anode electrode ANO are removed. (Fig. 8d)

A bank BA defining an opening area of each sub-pixel is formed on the substrate SUB on which the translucent anode electrode HAO and the transparent anode electrode ANO are formed. The area exposed by the bank BA is defined as an opening area emitting light. (Fig. 8e)

An organic light emitting layer OL expressing white light is applied on the entire surface of the substrate SUB on which the bank BA is formed. Subsequently, a cathode electrode CAT including a metallic material having high reflectivity is applied. Accordingly, in the (red) sub-pixel to which the micro-cavity is applied, the micro-cavity organic light-emitting diode MOLE in which the translucent anode electrode HANA, the organic light-emitting layer OL, and the cathode electrode CAT are stacked is formed. On the other hand, in general sub-pixels to which a micro-cavity is not applied, an organic light emitting diode OLE in which a transparent anode electrode ANO, an organic light emitting layer OL, and a cathode electrode CAT are stacked is formed. (Fig. 8f)

As described above, in the second embodiment of the present invention, the translucent anode electrode ANO is formed while leaving the first photoresist PR1 used when forming the transparent anode electrode ANO. Accordingly, in the process of forming the translucent anode electrode HAO, a process of forming a separate protective layer for protecting the already formed transparent anode electrode ANO may be omitted. That is, compared to the first embodiment, it has the effect of reducing the number of mask processes once.

In the second embodiment of the present invention, after first forming a transparent anode electrode ANO in pixels having a general structure, a translucent anode electrode HANA is formed in a specific pixel having a micro-cavity structure. This is an optimized method considering various factors such as the conditions for reducing the number of mask processes, the overall manufacturing process conditions, and the properties of the finished product and the materials used. However, the same order as in the first embodiment may be applied depending on conditions.

In addition, in the present invention, a micro-cavity structure is selectively applied only to specific sub-pixels whose luminous efficiency is particularly lower than that of other sub-pixels. Accordingly, compared to a case in which a micro-cavity structure optimized for each color is applied in all sub-pixels, the structure is simple and the manufacturing process is not complicated. That is, it is optimized and simplified as a structure and/method for obtaining uniform luminance or luminous efficiency.

It will be appreciated by those skilled in the art through the above description that various changes and modifications can be made without departing from the spirit of the present invention. Accordingly, the present invention should not be limited to the content described in the detailed description, but should be defined by the claims.

DL: Data wiring SL: Scan wiring
VDD: drive current wiring ST: switching TFT
DT: Driving TFT OLE: Organic light emitting diode
MOLE: Micro cavity organic light emitting diode
SG, DG: gate electrode SS, DS: source electrode
SD, DD: drain electrode SUB: substrate
CAT: cathode electrode (layer) ANO: (transparent) anode electrode (layer)
HANO: translucent anode electrode
BANK: Bank PAS: Shield
OL: organic light emitting layer OC: overcoat layer
HIL: hole injection layer HTL: hole transport layer
DH: drain contact hole PH: pixel contact hole

Claims (6)

delete delete Forming a transparent anode electrode in which the first photoresist is stacked on a first sub-pixel by applying a transparent conductive material to a first thickness on a substrate and patterning with a first photoresist;
Applying a translucent conductive material to a second thickness on the substrate on which the transparent anode electrode and the first photoresist are stacked, patterning with a second photoresist, and forming a translucent anode electrode on a second sub-pixel;
Simultaneously removing the first photoresist remaining on the transparent anode electrode and the second photoresist remaining on the translucent anode electrode;
Forming an organic light emitting layer on the surface of the substrate on which the transparent anode electrode and the translucent anode electrode are formed; And
And forming a cathode electrode of a reflective conductive material on the organic light-emitting layer.
The method of claim 3,
Forming the transparent anode electrode and forming the translucent anode electrode,
Applying the transparent conductive material;
Applying the first photoresist on the transparent conductive material;
Patterning the first photoresist;
Forming the transparent anode electrode by etching the transparent conductive material using the pattern of the first photoresist as a mask;
Applying the transflective conductive material while leaving the pattern of the first photoresist on the transparent anode electrode;
Applying the second photoresist over the transflective conductive material;
Patterning the second photoresist;
Forming the translucent anode electrode by etching the translucent conductive material using the pattern of the second photoresist as a mask; And
And simultaneously removing the first photoresist remaining on the transparent anode electrode and the second photoresist remaining on the translucent anode electrode.
The method of claim 3,
The step of applying the semi-permeable conductive material,
Applying a first transparent conductive layer;
Applying a semi-transparent metal layer on the first transparent conductive layer; And
And applying a second transparent conductive layer thinner than the first transparent conductive layer on the transflective metal layer.
The method of claim 3,
The translucent anode electrode is formed in the second sub-pixel selected from red, green, and blue sub-pixels,
The transparent anode electrode is formed in all sub-pixels except for the second sub-pixel.

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