KR102665677B1 - Organic light emitting display device - Google Patents

Abstract

An organic light emitting display device according to the present invention includes a substrate; a transistor disposed on the substrate; a planarization film covering the transistor; and an organic light emitting layer disposed on the planarization film and electrically connected to the transistor, a second electrode facing the first electrode, and an organic light emitting layer interposed between the first electrode and the second electrode. It includes a diode, and the first electrode includes: a transmission layer including a transparent conductive material; and a reflective layer interposed between the transmission layer and the planarization film and having a positive taper shape, wherein the organic light-emitting layer directly contacts the top surface and the side surface of the first electrode and directly contacts the planarization film.

Description

Organic light emitting display device {ORGANIC LIGHT EMITTING DISPLAY DEVICE}

The present invention relates to an organic light emitting display device.

Various display devices are being developed that can reduce the weight and volume, which are disadvantages of the cathode ray tube. These display devices include Liquid Crystal Display (LCD), Field Emission Display (FED), Plasma Display Panel (PDP), and Organic Light Emitting Display device; It can be implemented with OLED), etc.

Among these flat panel displays, organic light-emitting diode displays are self-luminous displays that excite organic compounds to emit light. They do not require the backlight used in LCDs, so they are lightweight and thin, and have the advantage of simplifying the process. . In addition, organic electroluminescent display devices are widely used because they can be manufactured at low temperatures, have a high-speed response speed of 1 ms or less, and have characteristics such as low power consumption, wide viewing angle, and high contrast. there is.

Organic light emitting diode displays include organic light emitting diodes that convert electrical energy into light energy. An organic light emitting diode includes an anode, a cathode, and an organic light emitting layer disposed between them. In an organic light emitting diode display, holes and electrons injected from an anode and a cathode combine inside the light emitting layer to form excitons, and the formed excitons change from the excited state to the ground state. ), it emits light and displays an image.

Recently, efforts are being made to provide high-resolution display devices with high PPI (Pixel Per Inch). However, when many pixels are placed in a limited space, the size of the pixels inevitably becomes small, and in this case, it may be difficult to secure the desired aperture ratio. Therefore, a method is required to secure the required aperture ratio while implementing a high-resolution display device.

The purpose of the present invention is to provide an organic light emitting display device having a structure in which banks are deleted. In particular, an object of the present invention is to provide an organic light emitting display device that can prevent the problem of the organic light emitting layer being separated at the end of the first electrode in the bank deletion structure.

An organic light emitting display device according to the present invention includes a substrate; a transistor disposed on the substrate; a planarization film covering the transistor; and an organic light emitting layer disposed on the planarization film and electrically connected to the transistor, a second electrode facing the first electrode, and an organic light emitting layer interposed between the first electrode and the second electrode. It includes a diode, and the first electrode includes: a transmission layer including a transparent conductive material; and a reflective layer interposed between the transmission layer and the planarization film and having a positive taper shape, wherein the organic light-emitting layer directly contacts the top surface and the side surface of the first electrode and directly contacts the planarization film.

The reflective layer may directly contact the planarization film.

The transmission layer may cover an upper surface of the reflective layer and expose a side surface of the reflective layer.

The transmission layer is located on the upper surface of the reflection layer and may have a smaller area than the reflection layer.

An organic light emitting display device, wherein the end of the transmission layer is positioned at a predetermined distance from the end of the reflection layer toward the center of the reflection layer.

An end of the first electrode may have a step-shaped cross-sectional shape.

The transmission layer extends to cover the top and side surfaces of the reflective layer, and an end of the transmission layer may directly contact the planarization film.

The thickness of the reflective layer may be thicker than the thickness of the transmission layer.

The reflective layer may have a thickness of 1000 to 2000 Å, and the transmission layer may have a thickness of 50 to 150 Å.

The first electrode may be a reflective electrode, and the second electrode may be a transmissive electrode.

The display device according to the present invention has a structure in which banks (or pixel definition films), which were conventionally formed to partition neighboring pixels, are eliminated. Therefore, the process time and process cost due to the addition of a process to form a bank can be reduced, process defects can be reduced, and process yield can be significantly improved.

The display device according to the present invention forms a first electrode of a specific shape in a bank deletion structure, thereby preventing the organic light emitting layer from separating at the end of the first electrode and causing a short circuit between the first electrode and the second electrode. . Accordingly, it has the advantage of providing a high-quality organic light emitting display device.

1 is a block diagram schematically showing an organic light emitting diode display device.
FIG. 2 is a schematic configuration diagram of the pixel shown in FIG. 1.
Figure 3 is a cross-sectional view schematically showing an organic light emitting display device according to a preferred embodiment of the present invention.
Figure 4 is a diagram for comparative explanation of the effects of the present invention.
Figure 5 is a diagram for explaining the shape of a first electrode according to an embodiment of the present invention.
Figure 6 is a diagram for explaining the shape of a first electrode according to another embodiment of the present invention.
Figure 7 is a diagram for explaining the shape of a first electrode according to another embodiment of the present invention.
Figure 8 shows an organic light emitting display device according to a comparative example, and is a diagram for comparing and explaining the effect of the present invention.
Figure 9 is a diagram for comparative explanation between a preferred embodiment of the present invention and the prior art.
Figure 10 is a diagram for explaining the shape of an organic light-emitting layer according to a modified example of the present invention.

Hereinafter, preferred embodiments of the present invention will be described with reference to the attached drawings. Like reference numerals refer to substantially the same elements throughout the specification. In the following description, if it is determined that a detailed description of a known technology or configuration related to the present invention may unnecessarily obscure the gist of the present invention, the detailed description will be omitted. In describing various embodiments, the same components may be representatively described at the beginning and omitted in other embodiments.

Terms containing ordinal numbers, such as first, second, etc., may be used to describe various components, but the components are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another.

1 is a block diagram schematically showing an organic light emitting diode display device. FIG. 2 is a schematic configuration diagram of the pixel shown in FIG. 1.

Referring to FIG. 1, the organic light emitting diode display device 10 according to the present invention includes a display driving circuit and a display panel (DIS).

The display driving circuit includes a data driving circuit 12, a gate driving circuit 14, and a timing controller 16, and writes the video data voltage of the input image to the pixels of the display panel DIS. The data driving circuit 12 converts digital video data (RGB) input from the timing controller 16 into an analog gamma compensation voltage and generates a data voltage. The data voltage output from the data driving circuit 12 is supplied to the data wires D1 to Dm. The gate driving circuit 14 sequentially supplies a gate signal synchronized with the data voltage to the gate wires G1 to Gn to select pixels of the display panel DIS to which the data voltage is written.

The timing controller 16 inputs timing signals such as the vertical synchronization signal (Vsync), horizontal synchronization signal (Hsync), data enable signal (Data Enable, DE), and main clock (MCLK) input from the host system 19. The operation timing of the data driving circuit 12 and the gate driving circuit 14 is synchronized. The data timing control signal for controlling the data driving circuit 12 includes a source sampling clock (Source Sampling Clock, SSC), a source output enable signal (Source Output Enable, SOE), etc. Gate timing control signals for controlling the gate driving circuit 14 include gate start pulse (Gate Start Pulse, GSP), gate shift clock (GSC), gate output enable signal (GOE), etc. Includes.

The host system 19 may be implemented as any one of a television system, set-top box, navigation system, DVD player, Blu-ray player, personal computer (PC), home theater system, and phone system. The host system 19 includes a system on chip (SoC) with a built-in scaler and converts digital video data (RGB) of the input image into a format suitable for display on the display panel (DIS). The host system 19 transmits timing signals (Vsync, Hsync, DE, MCLK) along with digital video data to the timing controller 16.

The display panel DIS includes a pixel array. The pixel array includes pixels defined by data lines (D1 to Dm, m is a positive integer) and gate lines (G1 to Gn, n is a positive integer). Each pixel includes an organic light emitting diode (OLED), which is a self-luminous device.

Referring further to FIG. 2 , in the display panel DIS, a plurality of data wires D and a plurality of gate wires G intersect, and pixels are arranged in a matrix form in each intersection area. Each pixel has an OLED, a driving thin film transistor (hereinafter referred to as TFT) (DT) that controls the amount of current flowing through the OLED, and a programming unit (SC) that sets the gate-source voltage of the driving TFT (DT). Includes.

The programming unit SC may include at least one switch TFT and at least one storage capacitor. The switch TFT is turned on in response to a gate signal from the gate wire (G), thereby applying the data voltage from the data wire (D) to one electrode of the storage capacitor. The driving TFT (DT) controls the amount of light emitted by the OLED by controlling the amount of current supplied to the OLED according to the amount of voltage charged in the storage capacitor. The amount of light emitted by OLED is proportional to the amount of current supplied from the driving TFT (DT). These pixels are connected to a high-potential voltage source (Evdd) and a low-potential voltage source (Evss), and receive high-potential power supply voltage and low-potential power supply voltage, respectively, from a power generator (not shown). TFTs constituting a pixel may be implemented as a p type or as an n type. Additionally, the semiconductor layer of the TFTs constituting the pixel may include amorphous silicon, polysilicon, or oxide. Hereinafter, the case where the semiconductor layer contains oxide will be described as an example. OLED includes an anode (ANO), a cathode (CAT), and an organic compound layer sandwiched between the anode (ANO) and the cathode (CAT). The anode (ANO) is connected to the driving TFT (DT).

Figure 3 is a cross-sectional view schematically showing an organic light emitting display device according to a preferred embodiment of the present invention. Figure 4 is a diagram for comparative explanation of the effects of the present invention.

Referring to FIG. 3, an organic light emitting diode display device according to a preferred embodiment of the present invention includes a display panel including a first substrate (SUB1) and a second substrate (SUB2) facing each other. The display panel may further include a filler layer FL interposed between the first substrate SUB1 and the second substrate SUB2. The filler layer FL may include multiple fillers. The filler layer FL may be provided to maintain a cell gap between the first substrate SUB1 and the second substrate SUB2.

The first substrate SUB1 may be a thin film transistor array substrate having pixels on which a thin film transistor T and an organic light emitting diode OLE are arranged. The second substrate SUB2 may be a color filter substrate on which a color filter is formed. The second substrate SUB2 may function as an encapsulation substrate. The first substrate SUB1 and the second substrate SUB2 may be bonded together using a sealant SL. The sealant SL may be disposed at the edges of the first and second substrates SUB1 and SUB2 to maintain a predetermined bonding gap.

The first substrate SUB1 may be made of glass or plastic. For example, the first substrate SUB1 may be made of a plastic material such as polyimide (PI), polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or polycarbonate (PC), and may have flexible characteristics.

On the first substrate SUB1, a thin film transistor T and an organic light emitting diode OLE connected to the thin film transistor T are formed. A light blocking layer (LS) and a buffer layer (BUF) may be formed between the first substrate (SUB1) and the thin film transistor (T). The light blocking layer (LS) is arranged to overlap the semiconductor layer of the thin film transistor (T), especially the channel, and serves to protect the oxide semiconductor device from external light. The buffer layer (BUF) serves to block ions or impurities diffusing from the first substrate (SUB1) and to block external moisture from penetrating.

The thin film transistor (T) includes a semiconductor layer (ACT), a gate electrode (GE), and source/drain electrodes (SE, DE).

A gate insulating film (GI) and a gate electrode (GE) are disposed on the semiconductor layer (ACT). The gate insulating film (GI) insulates the gate electrode (GE) and may be made of a silicon oxide film (SiOx), but is not limited thereto. The gate electrode GE is arranged to overlap the semiconductor layer ACT with the gate insulating film GI interposed therebetween. The gate electrode (GE) is made of copper (Cu), molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), nickel (Ni), neodymium (Nd), and tantalum (Ta). and tungsten (W), or an alloy thereof. The gate insulating layer GI and the gate electrode GE may be patterned using the same mask. In this case, the gate insulating layer GI and the gate electrode GE may have the same area. Although not shown, the gate insulating layer GI may be formed to cover the entire surface of the first substrate SUB1.

An interlayer insulating film (IN) is disposed on the gate electrode (GE). The interlayer insulating film (IN) insulates the gate electrode (GE) and the source/drain electrodes (SE, DE) from each other and may be made of a silicon oxide film (SiOx), a silicon nitride film (SiNx), or a multilayer thereof, but is limited thereto. That is not the case.

Source/drain electrodes (SE, DE) are disposed on the interlayer insulating film (IN). The source electrode (SE) and the drain electrode (DE) are arranged to be spaced apart from each other by a predetermined distance. The source electrode SE contacts one side of the semiconductor layer ACT through a source contact hole penetrating the interlayer insulating film IN. The drain electrode (DE) contacts the other side of the semiconductor layer (ACT) through a drain contact hole penetrating the interlayer insulating film (IN).

The source electrode (SE) and drain electrode (DE) can be made of a single layer or multiple layers. In the case of a single layer, molybdenum (Mo), aluminum (Al), chromium (Cr), gold (Au), titanium (Ti), It may be made of any one selected from the group consisting of nickel (Ni), neodymium (Nd), and copper (Cu), or an alloy thereof. In addition, when the source electrode (SE) and drain electrode (DE) are multilayered, they are a double layer of molybdenum/aluminum-neodymium, molybdenum/aluminum, titanium/aluminum, or copper/molytitanium, or molybdenum/aluminum-neodymium/molybdenum, molybdenum. It may be made of a triple layer of /aluminum/molybdenum, titanium/aluminum/titanium, or molytitanium/copper/molytitanium.

The structure of the thin film transistor (T) is not limited to the structure shown, and may be implemented in various structures such as bottom gate, top gate, and double gate structures.

As shown, the storage capacitor Cst may be formed in a triple structure in which first to third capacitor electrodes overlap, and may be implemented with a plurality of various layers as needed.

A passivation film (PAS) is located on the thin film transistor (T). The passivation film (PAS) protects the thin film transistor (T) and may be made of silicon oxide (SiOx), silicon nitride (SiNx), or multiple layers thereof.

A planarization film (OC) is located on the passivation film (PAS). The planarization film (OC) is used to flatten the lower step and can be made of organic materials such as photo acryl, polyimide, benzocyclobutene resin, and acrylate. there is.

An organic light emitting diode (OLE) is located on the planarization film (OC). The organic light emitting diode (OLE) includes a first electrode (E1), an organic light emitting layer (OL), and a second electrode (E2). The first electrode (E1) may be an anode, and the second electrode (E2) may be a cathode.

In more detail, the first electrode E1 is located on the planarization film OC. The first electrode E1 is connected to the source electrode SE of the thin film transistor T through a contact hole penetrating the passivation film PAS and the planarization film OC. One first electrode E1 may be allocated per pixel.

Since the organic light emitting display device according to a preferred embodiment of the present invention is implemented in a top emission type, the first electrode E1 includes a reflective layer RL and can function as a reflective electrode. That is, in the case of a top-emitting organic light emitting display device, in order to improve light emission efficiency, the direction of light generated by the organic light emitting diode (OLE) and radiated in multiple directions can be controlled in a preset direction (or direction). There is a need. In a top-emitting organic light emitting display device, the direction may be toward the second substrate SUB2. Therefore, the first electrode E1 needs to function as a reflective electrode.

The first electrode E1 may be made of multiple layers including a reflective layer RL. Hereinafter, for convenience of explanation, a case in which the first electrode E1 is formed of a double layer including a reflective layer RL will be described as an example. For example, the first electrode E1 may include a reflective layer RL and a transmissive layer TL. Here, both the reflective layer RL and the transmissive layer TL may be formed of a conductive material.

The reflective layer RL may include a conductive material (or reflective conductive material) with excellent reflectivity. The reflective layer RL may be made of aluminum (Al), copper (Cu), silver (Ag), nickel (Ni), or an alloy thereof, and is preferably made of APC (silver/palladium/copper alloy). However, it is not limited to this. The reflective layer RL may be located at the bottom of the layers constituting the first electrode E1. That is, the reflective layer RL may be a layer in direct contact with the upper surface of the planarization layer OC.

The reflective layer RL is prepared to have a preset first thickness. Preferably, the thickness of the reflective layer RL may be 1000 to 2000 Å. The cross-sectional shape of the reflective layer RL has a positive taper shape.

The transmission layer (TL) may be located on the reflection layer (RL). The transmission layer TL may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO). The transmission layer (TL) is a layer prepared to match a preset work function and can function as a practical anode electrode.

The transmission layer TL is prepared to have a preset second thickness. The second thickness is set smaller than the first thickness. Preferably, the thickness of the transmission layer (TL) may be 50 to 150 Å. Assuming the total thickness at which the first electrode E1 can perform its function, the total thickness of the first electrode E1 is the sum of the first thickness of the reflective layer RL and the second thickness of the transmissive layer TL. Can be, where the second thickness can be set to be thinner than the first thickness.

The cross-sectional shape of the transmission layer TL may have a constant taper shape. Because the transmission layer is formed relatively very thin, the ends may not have a tapered shape. Since the transmission layer TL is formed relatively very thin, at least one end may not have a reverse taper shape.

A display device according to a preferred embodiment of the present invention does not form a bank (or pixel definition film) provided to partition neighboring pixels. That is, referring to FIG. 9, conventionally, a bank BN was provided to partition the pixels PXL1 and PXL2 between the neighboring pixels PXL1 and PXL2. However, in a preferred embodiment of the present invention, the bank BN for dividing the pixels PXL1 and PXL2 between the neighboring pixels PXL1 and PXL2 is omitted. Therefore, the process time and process cost due to the addition of a process to form a bank can be reduced, process defects can be reduced, and process yield can be significantly improved.

In addition, since the preferred embodiment of the present invention has a structure in which the bank is omitted, an additional process for aligning the bank to a specific position on the planarization film OC is not required. Considering that accurate alignment is not easy because high-resolution display devices with high PPI (Pixel Per Inch) have relatively narrow bank widths, the present invention can significantly improve process yield and reduce the risk of bank misalignment. It has the advantage of preventing deterioration of image quality characteristics.

Additionally, the bank is generally formed to cover the end of the first electrode E1. Accordingly, since a part of the first electrode E1 covered by the bank is allocated to a non-emission area, the aperture ratio is reduced by the area. Since the preferred embodiment of the present invention has a structure in which banks are omitted, it has the advantage of securing a sufficient aperture ratio.

Additionally, the display device according to a preferred embodiment of the present invention may be implemented as a transparent display device. For example, a pixel may include an emissive area (EA) and a transmissive area (TA). The emission area (EA) can be defined as an area where light to implement an input image is emitted. The transmission area (TA) can be defined as an area through which external light is transmitted so that the user can recognize objects located on the back of the display device. If a bank is placed in such a transmission area (TA), the light passing through the corresponding portion may have a yellowish color, which may cause visual discomfort to the user. Since the preferred embodiment of the present invention has a structure in which banks are omitted, it has the advantage of providing a high-quality transparent display device. Furthermore, the display device according to a preferred embodiment of the present invention can further improve transmittance by removing the planarization film (OC) from the transmission area (TA).

The organic light emitting layer (OL) is located on the first electrode (E1). The organic light emitting layer OL may be formed widely over the entire surface of the first substrate SUB1. The organic light emitting layer (OL) is a layer that emits light by combining electrons and holes, and includes an emission layer (EML), a hole injection layer (HIL), a hole transport layer (HTL), and an electron layer (HTL). It may further include one or more of an electron transport layer (ETL) and an electron injection layer (EIL). The organic light emitting layer (OL) can generate white light and can implement a specific color by combining it with a color filter.

The organic light emitting layer OL is formed to completely cover the first electrode E1 along the surface shape of the first electrode E1. The organic light-emitting layer OL is in direct contact with both the side surface and the top surface of the first electrode E1. The organic light emitting layer OL is in direct contact with the planarization film OC in a region where the first electrode E1 is not located. As will be described later, since the organic light emitting display device according to a preferred embodiment of the present invention has a structure in which the bank is deleted, the organic light emitting layer OL and the first electrode E1 overlap in the area where the organic light emitting layer OL and the first electrode E1 overlap. There is no layer interposed between the electrodes E1, and there is no layer interposed between the organic emission layer OL and the planarization film OC in areas where the organic emission layer OL and the first electrode E1 do not overlap.

The organic light emitting layer OL extends long to cover the side surface and the top surface of the first electrode E1 and can maintain continuity without being separated. That is, since the reflective layer (RL) and the transmissive layer (TL) of the first electrode (E1) do not have at least a reverse taper shape, the organic light emitting layer (OL) is continuous in the entire area without being separated by the first electrode (E1). can be maintained.

Referring to FIG. 4 , when the end of the first electrode E1 has a reverse taper shape, the organic light emitting layer OL may not have continuity in the area corresponding to the end of the first electrode E1 and may be separated. In this case, a short circuit may occur between the first electrode E1 and the second electrode E2 in the area where the organic light emitting layer OL is separated. In a preferred embodiment of the present invention, the organic light emitting layer can be prevented from being separated by forming the first electrode E1 to have a preset shape and/or a preset thickness. Accordingly, a preferred embodiment of the present invention can prevent a defect in which the corresponding pixel becomes dark due to a short circuit between the first electrode E1 and the second electrode E2.

The second electrode E2 is located on the organic light emitting layer OL. The second electrode E2 may be formed widely on the entire surface of the first substrate SUB1. Since the display device according to the preferred embodiment of the present invention is implemented in a top-emitting manner, the second electrode E2 can function as a transmission electrode. The second electrode (E2) may be formed of a transparent conductive material such as indium tin oxide (ITO) or indium zinc oxide (IZO), and may be made of magnesium (Mg) or calcium (Ca) that is thin enough to allow light to pass through. ), aluminum (Al), silver (Ag), or alloys thereof.

Although not shown, a capping layer and a blocking layer may be sequentially disposed on the second electrode E2. The capping layer may be a layer for compensating the color viewing angle. The blocking layer may be a layer to block moisture and foreign substances from entering the organic light emitting diode (OLE). The blocking layer may be made of an inorganic material such as silicon oxide (SiOx) or silicon nitride (SiNx). The capping layer and the blocking layer may be formed widely over the entire surface of the substrate to cover a plurality of pixels.

On the second substrate SUB2, a black matrix BM and a color filter CF are formed. On the second substrate SUB2, the stacking order of the black matrix BM and the color filter CF may be changed. That is, the color filter (CF) may be formed after the black matrix (BM) is formed, and the black matrix (BM) may be formed after the color filter (CF) is formed. The black matrix (BM) can prevent color mixing defects from occurring between neighboring pixels. The black matrix BM may be disposed in a non-emission area so as to expose at least the emission area.

The color filter (CF) may include red (R), blue (B), and green (G) color filters (CF). The pixel may include pixels that emit red (R), blue (B), and green (G), and a color filter (CF) may be assigned to each of the corresponding pixels. Red (R), blue (B), and green (G) color filters (CF) may be partitioned by a black matrix (BM). If necessary, the pixel may further include white (W) pixels.

Figure 5 is a diagram for explaining the shape of a first electrode according to an embodiment of the present invention.

Referring to FIG. 5 , the first electrode E1 may include a reflective layer (RL) and a transmissive layer (TL) sequentially stacked on the planarization film (OC). The transmission layer TL may be formed to cover the upper surface of the reflection layer RL. That is, the transmission layer TL may have an area substantially the same as the upper surface of the reflection layer RL. The transmission layer TL may expose a side surface of the reflection layer RL.

Figure 6 is a diagram for explaining the shape of a first electrode according to another embodiment of the present invention.

Referring to FIG. 6 , the first electrode E1 may include a reflective layer RL and a transmissive layer TL sequentially stacked on the planarization film OC. The transmission layer TL may be formed to cover a portion of the upper surface of the reflection layer RL. That is, the transmission layer TL may be located on the upper surface of the reflection layer RL, but may be located inside the reflection layer RL. For example, the transmission layer TL may be located on the upper surface of the reflection layer RL, but may have an area smaller than that of the reflection layer RL. For example, the end of the transmission layer TL may be positioned at a predetermined distance G from the end of the reflection layer RL toward the center of the reflection layer RL. In this case, because the end of the first electrode E1 may be formed in a step shape, a sharp step may not be formed at the end of the first electrode E1. Accordingly, a preferred embodiment of the present invention can prevent defects in which the organic light emitting layer OL is separated due to a step at an end of the first electrode E1.

Figure 7 is a diagram for explaining the shape of a first electrode according to another embodiment of the present invention.

Referring to FIG. 7 , the first electrode E1 may include a reflective layer (RL) and a transmissive layer (TL) sequentially stacked on the planarization film (OC). The transmission layer TL may be formed to cover the top surface and the side surface of the reflection layer RL. The transmission layer TL may be extended to completely cover the reflection layer RL, and its end may be in direct contact with the planarization layer OC. As described above, since the transmission layer TL is a layer that substantially functions as an anode electrode, the area occupied by the transmission layer TL may correspond to the light emitting area. Accordingly, a preferred embodiment of the present invention can secure a relatively large light emitting area by forming the transmission layer TL relatively long.

<Comparative example>

Figure 8 shows an organic light emitting display device according to a comparative example, and is a diagram for comparative explanation of the effect of the present invention.

Referring to FIG. 8, the organic light emitting display device according to the comparative example may be implemented as a top emission type.

Specifically, the organic light emitting display device according to the comparative example includes a thin film transistor substrate (SUB). On the thin film transistor substrate (SUB), a thin film transistor (T) assigned to each pixel and an organic light emitting diode (OLE) connected to the thin film transistor (T) are disposed.

In the case of a bottom-emitting organic light-emitting display device, in order to improve luminous efficiency, it is necessary to control the direction of light generated by the organic light-emitting diode (OLE) and radiated in multiple directions to a preset direction (or direction). there is. In a bottom-emitting organic light emitting display device, the direction may be toward the thin film transistor substrate (SUB). For this purpose, the first electrode E1 needs to function as a transmission electrode and the second electrode E2 needs to function as a reflective electrode. Therefore, the first electrode is formed of a transparent conductive material such as ITO, and the second electrode E2 is made of a metal material such as magnesium (Mg), calcium (Ca), aluminum (Al), silver (Ag), or alloys thereof. It can be formed as

In this structure, the first electrode is formed to have an inverse taper shape on the planarization film by a reaction mechanism between the ITO constituting the first electrode and the organic material constituting the planarization film. For example, when patterning ITO to form a first electrode, due to an adhesion problem between ITO and the organic material constituting the planarization film, when wet etching is performed, the top of the organic material (organic material and ITO) As the etching reaction occurs first at the interfacial interface, ITO may have a reverse taper shape.

As described above, when the end of the first electrode E1 has a reverse taper shape, the organic light emitting layer OL may not have continuity in the area corresponding to the end of the first electrode E1 and may be separated. In this case, a short circuit may occur between the first electrode E1 and the second electrode E2 in the area where the organic light emitting layer OL is separated.

In order to prevent the end of the first electrode E1 from having a reverse taper shape, a method of forming the ITO constituting the first electrode E1 thin may be considered. However, in order for the first electrode E1 to function properly, it is necessary to secure a thickness of 1000 Å or more, so it is difficult to achieve the above objective by simply forming the first electrode E1 thin.

As another method to prevent the above defect, as shown, a tapered bank BN that covers the end of the first electrode E1 may be additionally formed. Since the bank BN covers the end of the first electrode E1 having an inverse taper shape, a defect in which the organic light emitting layer OL formed thereafter is separated by the end of the first electrode E1 can be prevented. . However, in this case, since the end of the first electrode E1 is shielded by the bank BN, the aperture ratio is reduced by the shielding area OV. Therefore, there is a problem that it is difficult to secure the aperture ratio required for a high-resolution display device.

In contrast, in a preferred embodiment of the present invention, the first electrode E1 is configured to include a reflective layer (RL, FIG. 3) and a transmission layer (TL, FIG. 3), and the reflective layer (RL, FIG. 3) includes a metallic material. 3) can be set as a layer directly in contact with the planarization film. Accordingly, since the reflective layer RL (FIG. 3) can be formed to have a positive taper, a short circuit problem between the first electrode E1 and the second electrode E2 that occurs when the organic light emitting layer OL is separated is prevented. can do.

In addition, since the preferred embodiment of the present invention does not require additional formation of the bank BN, a sufficient aperture ratio can be secured within a limited space. Accordingly, since the required aperture ratio can be sufficiently secured even in a high-resolution display device, a high-quality, high-resolution display device can be implemented.

<Variation example>

Figure 10 is a diagram for explaining the shape of an organic light-emitting layer according to a modified example of the present invention.

Referring to (a) of FIG. 10, as described in the embodiment of the present invention, the organic light emitting layer OL is integrated to cover the first electrodes E1 disposed in the neighboring pixels PXL1 and PXL2. It can be formed as For example, the organic light emitting layer OL may be formed through an open mask having one opening that simultaneously exposes a plurality of pixels PXL1 and PXL2. Accordingly, the organic light emitting layer OL may be implemented as one layer covering the plurality of first electrodes E1.

Additionally, referring to (b) of FIG. 10, one organic light emitting layer (OL) according to a modified example of the present invention may be allocated per pixel. That is, the organic light emitting layer OL may be disposed one by one for each pixel PXL1 and PXL2, and the organic light emitting layers OL disposed in neighboring pixels PXL1 and PXL2 may be separated from each other and may not contact each other. For example, the organic light emitting layer OL may be formed through a fine metal mask (FMM) mask having a plurality of openings that respectively expose the pixels PXL1 and PXL2. Accordingly, the organic light emitting layers OL may be assigned one to each pixel PXL1 and PXL2 and may be separated from each other. In this case as well, the organic light emitting layer OL may be formed to cover the first electrode E1 formed in the corresponding pixel and may not be separated by the first electrode E1 as described above.

Through the above-described content, those skilled in the art will be able to make various changes and modifications without departing from the technical spirit of the present invention. Therefore, the technical scope of the present invention should not be limited to what is described in the detailed description of the specification, but should be determined by the scope of the patent claims.

SUB1: 1st substrate SUB2: 2nd substrate
T: Transistor OLE: Organic light emitting diode
E1: first electrode TL: transmission layer
RL: Reflective layer OL: Organic light emitting layer
E2: Second electrode CF: Color filter

Claims (10)

Board;
a transistor disposed on the substrate;
a planarization film covering the transistor; and
An organic light emitting diode including a first electrode disposed on the planarization film and electrically connected to the transistor, a second electrode facing the first electrode, and an organic light emitting layer interposed between the first electrode and the second electrode. Including,
The first electrode is,
A transmission layer containing a transparent conductive material; and
It is interposed between the transmission layer and the planarization film and includes a reflective layer having a positive taper shape,
The organic light emitting layer is,
An organic light emitting display device that is in direct contact with an upper surface of the transmission layer and side surfaces of the transmission layer and the reflection layer, and is in direct contact with the planarization film.
According to claim 1,
The reflective layer is,
An organic light emitting display device that is in direct contact with the planarization film.
According to claim 1,
The transmission layer is,
An organic light emitting display device covering an upper surface of the reflective layer and exposing a side surface of the reflective layer.
According to claim 1,
The transmission layer is,
An organic light emitting display device located on an upper surface of the reflective layer and having a smaller area than the reflective layer.
According to claim 4,
The end of the transmission layer is,
An organic light emitting display device positioned at a predetermined distance from an end of the reflective layer toward the center of the reflective layer.
According to claim 4,
The end of the first electrode is,
An organic light emitting display device having a step-shaped cross-sectional shape.
delete According to claim 1,
The thickness of the reflective layer is,
An organic light emitting display device that is thicker than the thickness of the transmission layer.
According to claim 8,
The reflective layer is,
It has a thickness of 1000~2000Å,
The transmission layer is,
An organic light emitting display device with a thickness of 50 to 150 Å.
According to claim 1,
The first electrode is a reflective electrode,
An organic light emitting display device, wherein the second electrode is a transmission electrode.

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