Electroluminescence Display

Abstract

This application relates to an electroluminescent display device having a cathode electrode having an encapsulation function. The electroluminescent display device according to this application comprises a substrate, an anode electrode, a light-emitting layer, and a cathode electrode. The anode electrode is disposed on the substrate. The light-emitting layer is disposed on the anode electrode. The cathode electrode is disposed on the light-emitting layer. The cathode electrode comprises at least two conductive layers sequentially stacked.

Description

Technology Field

[0001] This application relates to an electroluminescent display device having a cathode electrode having an encapsulation function. In particular, this application relates to an electroluminescent display device that performs the encapsulation function using the cathode electrode itself, without having a separate encapsulation layer to protect the light-emitting element. Background Technology

[0002] Recently, various types of display devices, such as CRTs (Cathode Ray Tubes), LCDs (Liquid Crystal Displays), PDPs (Plasma Display Panels), and Luminescent Displays, have been developed and are advancing. These diverse display devices are utilized to display image data in a wide range of products, including computers, mobile phones, ATMs, and vehicle navigation systems, each tailored to its unique characteristics.

[0003] In particular, organic electroluminescent displays, which are self-emissive display devices, face a problem where the lifespan is shortened due to damage to the organic components if foreign substances such as moisture and gas penetrate the device from the outside. To prevent this problem, a technology has been proposed to apply an encapsulation layer to protect the organic light-emitting device.

[0004] Establishing an encapsulation layer requires a separate process, which increases process and manufacturing costs. Furthermore, if the interface characteristics between the encapsulation layer and the cathode electrode of the organic light-emitting diode are poor, the full encapsulation performance cannot be guaranteed. Therefore, there is a need to develop technology for a new encapsulation layer structure that simplifies the manufacturing process and reduces production costs while preventing the intrusion of external moisture or foreign substances. The problem to be solved

[0005] The purpose of this application is to overcome the problems of the prior art by providing an electroluminescent display device that secures excellent encapsulation performance using the cathode electrode itself, without separately providing an encapsulation layer to protect the organic light-emitting element. Another purpose of this application is to provide an electroluminescent display device that can reduce manufacturing costs by simplifying the manufacturing process through the configuration of the cathode electrode to have an encapsulation function. means of solving the problem

[0006] To achieve the above objective, the electroluminescent display device according to this application comprises a substrate, an anode electrode, a light-emitting layer, and a cathode electrode. The anode electrode is disposed on the substrate. The light-emitting layer is disposed on the anode electrode. The cathode electrode is disposed on the light-emitting layer. The cathode electrode comprises at least two conductive layers sequentially stacked.

[0007] For example, the conductive layers include a first metal oxide layer made of a metal oxide material, a first metal layer made of a metal material, and a second metal oxide layer made of a metal oxide material.

[0008] For example, the conductive layers are laminated on the second metal oxide layer and further include a second metal layer made of a metal material.

[0009] For example, the conductive layers include a first metal layer made of a metal material, a first metal oxide layer made of a metal oxide material, and a second metal layer made of a metal material.

[0010] For example, the conductive layers are laminated on the second metal layer and further include a second metal oxide layer made of a metal oxide material.

[0011] For example, the conductive layers include a first metal layer made of a metal material, a first metal oxide layer made of a metal oxide material, and a resin layer made of a conductive resin material.

[0012] For example, the conductive layers are laminated on the resin layer and further include a second metal layer made of a metal material.

[0013] For example, the conductive layers are laminated on the second metal layer and further include a second metal oxide layer made of a metal oxide material.

[0014] For example, the conductive layers include a first metal oxide layer made of a metal oxide material, a first metal layer made of a metal material, and a resin layer made of a conductive resin material.

[0015] For example, the conductive layers are laminated on the resin layer and further include a second metal oxide layer made of a metal oxide material.

[0016] For example, the conductive layers are laminated on the second metal oxide layer and further include a second metal layer made of a metal material.

[0017] For example, the conductive layers include a first conductive layer in contact with the light-emitting layer, a second conductive layer in contact with the first conductive layer, and a third conductive layer in contact with the second conductive layer.

[0018] For example, each of the first conductive layer and the third conductive layer comprises at least one of a metal layer and a metal oxide layer. The thickness of the metal layer is thicker than the thickness of the metal oxide layer.

[0019] For example, the thickness of the metal oxide layer is 10 Å to 200 Å. The thickness of the metal layer is 100 Å to 3,000 Å.

[0020] For example, the second conductive layer includes a conductive resin material.

[0021] For example, the metal material includes any one selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The metal oxide material includes any one selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO).

[0022] For example, a conductive resin material comprises a domain material comprising any one of Alq3, TmPyPB, Bphen, TAZ, and TPB, and a dopant composed of an alkali metal material such as Li, Cs, Cs2O3, CsN3, Rb2, and C60 dispersed within the domain material. Effects of the invention

[0023] The electroluminescent display device according to this application has a structure in which a cathode electrode constituting an organic light-emitting element has at least two layers of conductive layers sequentially stacked. In particular, it has a structure in which a first conductive layer containing a metallic material such as aluminum and a second conductive layer containing a metal oxide layer such as aluminum oxide are stacked. Accordingly, by further providing an encapsulation function to the cathode electrode, the cathode electrode and the encapsulation layer can be formed as a single structure in a single process for forming the cathode electrode. As a result, the manufacturing process is simplified and manufacturing costs can be reduced. In addition, since the cathode electrode having an encapsulation function is formed with a structure made of a multilayer conductive material, the bonding strength between the thin films is excellent, so damage such as delamination does not occur. Accordingly, this application can provide an electroluminescent display device having a cathode electrode having an encapsulation function that has excellent performance in blocking foreign substances penetrating from the outside. Brief explanation of the drawing

[0024] FIG. 1 is a diagram showing the schematic structure of an electroluminescent display device according to this application. FIG. 2 is a diagram showing the circuit configuration of a pixel constituting an electroluminescent display device according to this application. FIG. 3 is a plan view showing the structure of pixels arranged in an electroluminescent display device according to this application. FIG. 4 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along II-II' of FIG. 3. FIG. 5 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along I-I' of FIG. 1. FIG. 6 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along III-III' of FIG. 1. FIGS. 7a and 7b are cross-sectional views showing a stacked structure of a light-emitting diode in an electroluminescent display device according to the first embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 8 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the second embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 9 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the third embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 10 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the fourth embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 11 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the fifth embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 12 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the 6th embodiment of this application, enlarged from the rectangular area (X) of FIG. 4. FIG. 13 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the 7th embodiment of this application. FIG. 14 is a cross-sectional view showing the structure of an electroluminescent display device according to the eighth embodiment of this application. FIG. 15 is a cross-sectional view showing the structure of an electroluminescent display device according to the ninth embodiment of this application. FIG. 16 is a cross-sectional view showing the structure of an electroluminescent display device according to another example of the ninth embodiment of this application. FIG. 17 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to one application example of this application. FIG. 18 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application example of this application. FIG. 19 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application example of this application. FIG. 20 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application example of this application. Specific details for implementing the invention

[0025] The advantages and features of this application and the methods for achieving them will become clear by referring to the examples described below in detail together with the accompanying drawings. However, this application is not limited to the examples disclosed below but may be embodied in various different forms; the examples of this application are provided merely to ensure that the disclosure of this application is complete and to fully inform those skilled in the art of the scope of the invention to which the invention of this application belongs, and the invention of this application is defined only by the scope of the claims.

[0026] Shapes, sizes, proportions, angles, quantities, etc. disclosed in the drawings for illustrating an example of this application are exemplary and are not limited to the matters depicted herein. Throughout the specification, the same reference numerals refer to the same components. Furthermore, in describing the examples of this application, detailed descriptions of related prior art are omitted if it is determined that such detailed descriptions would unnecessarily obscure the essence of the application.

[0027] Where terms such as 'includes,' 'have,' and 'consists of' mentioned in this application specification are used, other parts may be added unless 'only' is used. Where a component is expressed in the singular, it includes cases where it is in the plural unless specifically stated otherwise.

[0028] In interpreting the components, they are interpreted to include a margin of error even in the absence of a separate explicit statement.

[0029] In the case of describing a positional relationship, for example, when the positional relationship between two parts is described using expressions such as 'on,' 'upper,' 'lower,' or 'next to,' one or more other parts may be located between the two parts unless 'immediately' or 'directly' is used.

[0030] In the case of an explanation of a temporal relationship, for example, when a temporal sequence is explained using 'after', 'following', 'next', 'before', etc., it may include cases where the sequence is not continuous unless 'immediately' or 'directly' is used.

[0031] Although terms such as "first," "second," etc. are used to describe various components, these components are not limited by these terms. These terms are used merely to distinguish one component from another. Accordingly, the "first component" mentioned below may be the "second component" within the technical scope of this application.

[0032] The term “at least one” should be understood to include all combinations that can be presented from one or more related items. For example, the meaning of “at least one of the first item, the second item and the third item” may mean not only the first item, the second item or the third item individually, but also all combinations of items that can be presented from two or more of the first item, the second item and the third item.

[0033] The features of each of the various examples of this application may be combined or combined with one another, either partially or wholly, and may technically enable various interlocking and operation. Each example may be implemented independently of one another or may be implemented together in an interlocking relationship.

[0034] Hereinafter, an example of a display device according to this application will be described in detail with reference to the attached drawings. In assigning reference numerals to the components of each drawing, the same components may have the same reference numeral as much as possible, even if they are shown in different drawings.

[0035] Hereinafter, this application will be described in detail with reference to the attached drawings. FIG. 1 is a drawing showing the schematic structure of an electroluminescent display device according to this application. In FIG. 1, the X-axis represents a direction parallel to the scan wiring, the Y-axis represents a direction parallel to the data wiring, and the Z-axis represents the height direction of the display device.

[0036] Referring to FIG. 1, the electroluminescent display device according to this application includes a substrate (110), a gate (or scan) driving unit (200), a data pad unit (300), a source driving integrated circuit (410), a flexible wiring film (430), a circuit board (450), and a timing control unit (500).

[0037] The substrate (110) may include an insulating material or a material having flexibility. The substrate (110) may be made of glass, metal, plastic, etc., but is not limited thereto. If the electroluminescent display device is a flexible display device, the substrate (110) may be made of a flexible material such as plastic. For example, it may include a transparent polyimide material.

[0038] The substrate (110) may be divided into a display area (DA) and a non-display area (NDA). The display area (DA) is an area where an image is displayed and may be defined in most of the area including the central part of the substrate (110), but is not limited thereto. Scan lines (or gate lines), data lines, and pixels are formed in the display area (DA). The pixels include a plurality of sub-pixels, and each of the plurality of sub-pixels includes scan lines and data lines.

[0039] The non-display area (NDA) is an area where no image is displayed and may be defined at the edge portion of the substrate (110) to surround all or part of the display area (DA). A gate driver (200) and a data pad portion (300) may be formed in the non-display area (NDA).

[0040] The gate driver (200) supplies scan (or gate) signals to the scan lines according to the gate control signal input from the timing control unit (500). The gate driver (200) may be formed in a non-display area (NDA) outside one side of the display area (DA) of the base substrate (110) in a GIP (gate driver in panel) manner. The GIP method refers to a structure in which the gate driver (200) is formed directly on the substrate (110).

[0041] The data pad section (300) supplies data signals to the data wires according to a data control signal input from the timing control section (500). The data pad section (300) is manufactured as a driving chip and mounted on a flexible wiring film (430), and can be attached to a non-display area (NDA) outside one side of the display area (DA) of the substrate (110) using a tape automated bonding (TAB) method.

[0042] The source driving integrated circuit (410) receives digital video data and a source control signal from the timing control unit (500). The source driving integrated circuit (410) converts the digital video data into analog data voltages according to the source control signal and supplies them to the data wires. When the source driving integrated circuit (410) is manufactured as a chip, it can be mounted on a flexible wiring film (430) using a COF (chip on film) or COP (chip on plastic) method.

[0043] In the flexible wiring film (430), wirings connecting the data pad section (300) and the source driving integrated circuit (410), and wirings connecting the data pad section (300) and the circuit board (450) may be formed. The flexible wiring film (430) is attached to the data pad section (300) using an anisotropic conducting film, thereby allowing the wirings of the data pad section (300) and the flexible film (430) to be connected.

[0044] The circuit board (450) can be attached to flexible wiring films (430). The circuit board (450) may have a number of circuits implemented with driving chips mounted on it. For example, a timing control unit (500) may be mounted on the circuit board (450). The circuit board (450) may be a printed circuit board or a flexible printed circuit board.

[0045] The timing control unit (500) receives digital video data and timing signals from an external system board through a cable of the circuit board (450). Based on the timing signals, the timing control unit (500) generates a gate control signal for controlling the operation timing of the gate driver (200) and a source control signal for controlling the source driver integrated circuits (410). The timing control unit (500) supplies the gate control signal to the gate driver (200) and supplies the source control signal to the source driver integrated circuits (410). Depending on the product, the timing control unit (500) may be formed with the source driver integrated circuit (410) and a single driver chip and mounted on the substrate (110).

[0046] FIG. 2 is a diagram showing the circuit configuration of a pixel constituting an electroluminescent display device according to this application. FIG. 3 is a plan view showing the structure of pixels according to this application. FIG. 4 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along II-II' of FIG. 3.

[0047] Referring to FIGS. 2 through 4, a pixel of a display device is defined by a scan line (SL), a data line (DL), and a driving current line (VDD). Inside a pixel of the display device, there is a switching thin-film transistor (ST), a driving thin-film transistor (DT), a light-emitting diode (OLE), and an auxiliary capacitance (Cst). A high potential voltage is applied to the driving current line (VDD) to drive the light-emitting diode (OLE).

[0048] For example, a switching thin-film transistor (ST) may be placed at the intersection of a scan line (SL) and a data line (DL). The switching thin-film transistor (ST) includes a switching gate electrode (SG), a switching source electrode (SS), and a switching drain electrode (SD). The switching gate electrode (SG) is connected to the scan line (SL). The switching source electrode (SS) is connected to the data line (DL), and the switching drain electrode (SD) is connected to a driving thin-film transistor (DT). The switching thin-film transistor (ST) functions to select a pixel to be driven by applying a data signal to the driving thin-film transistor (DT).

[0049] The driving thin-film transistor (DT) functions to drive the light-emitting diode (OLE) of a pixel selected by the switching thin-film transistor (ST). The driving thin-film transistor (DT) includes a driving gate electrode (DG), a driving source electrode (DS), and a driving drain electrode (DD). The driving gate electrode (DG) is connected to the switching drain electrode (SD) of the switching thin-film transistor (ST). For example, the switching drain electrode (SD) is connected through a drain contact hole (DH) that penetrates the gate insulating film (GI) covering the driving gate electrode (DG). The driving source electrode (DS) is connected to the driving current wiring (VDD), and the driving drain electrode (DD) is connected to the anode electrode (ANO) of the light-emitting diode (OLE). An auxiliary capacitance (Cst) is placed between the driving gate electrode (DG) of the driving thin-film transistor (DT) and the anode electrode (ANO) of the light-emitting diode (OLE).

[0050] The driving thin-film transistor (DT) is placed between the driving current wiring (VDD) and the light-emitting diode (OLE). The driving thin-film transistor (DT) adjusts the amount of current flowing from the driving current wiring (VDD) to the light-emitting diode (OLE) according to the magnitude of the voltage of the gate electrode (DG) connected to the drain electrode (SD) of the switching thin-film transistor (ST).

[0051] A light-emitting diode (OLE) comprises an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT). The light-emitting diode (OLE) emits light according to a current controlled by a driving thin-film transistor (DT). In other words, since the amount of light emitted by the light-emitting diode (OLE) is controlled according to the current controlled by the driving thin-film transistor (DT), the brightness of the electroluminescent display device can be controlled. The anode electrode (ANO) of the light-emitting diode (OLE) is connected to the driving drain electrode (DD) of the driving thin-film transistor (DT), and the cathode electrode (CAT) is connected to a low power supply wiring (VSS) to which a low potential voltage is supplied. That is, the light-emitting diode (OLE) is driven by a low potential voltage and a high potential voltage controlled by the driving thin-film transistor (DT).

[0052] A protective film (PAS) is laminated on the surface of a substrate (110) on which thin-film transistors (ST, DT) are formed. It is preferable that the protective film (PAS) be formed from an inorganic film such as silicon oxide or silicon nitride. A planarization film (PL) is laminated on the protective film (PAS). The planarization film (PL) is a thin film intended to flatten the surface of the substrate (110) on which thin-film transistors (ST, DT) are formed, as the surface may not be uniform. To make the height difference uniform, the planarization film (PL) may be formed from an organic material. Pixel contact holes (PH) are formed in the protective film (PAS) and the planarization film (PL) to expose a portion of the drain electrode (DD) of the driving thin-film transistor (DT).

[0053] An anode electrode (ANO) is formed on the upper surface of the planarization film (PL). The anode electrode (ANO) is connected to the drain electrode (DD) of the driving thin-film transistor (DT) through a pixel contact hole (PH). The components of the anode electrode (ANO) may vary depending on the light-emitting structure of the light-emitting diode (OLE). For example, in the case of a bottom-emitting type that provides light toward the substrate (110), it can be formed from a transparent conductive material. As another example, in the case of emitting light in the upper direction facing the substrate (110), it can be formed from a metallic material with excellent light reflectivity.

[0054] In the case of this application, the cathode electrode is characterized by having an encapsulation function, thus having a structure suitable for a bottom-emitting type. For a bottom-emitting type, it is preferable that the anode electrode (ANO) be formed from a transparent conductive material. For example, it may include an oxidative conductive material such as indium zinc oxide or indium tin oxide. The anode electrode may be composed of a single layer or multiple layers. The anode electrode (ANO) may include an anti-reflective material. For example, if the anode electrode (ANO) is composed of an anti-reflective electrode, the anode electrode (ANO) may consist of a bottom layer containing molybdenum-copper oxide (MoCuOx) and a top layer containing copper (Cu).

[0055] A light-emitting layer (EL) is laminated on the anode electrode (AN0). The light-emitting layer (EL) may be formed over the entire display area (DA) of the substrate (110) to cover the anode electrode (ANO) and the bank (BA). According to one example, the light-emitting layer (EL) may include two or more vertically laminated light-emitting portions to emit white light. For example, the light-emitting layer (EL) may include a first light-emitting portion and a second light-emitting portion to emit white light by mixing a first light and a second light.

[0056] As another example, the light-emitting layer (EL) may include any one of a blue light-emitting part, a green light-emitting part, and a red light-emitting part for emitting light corresponding to the color set in the pixel. Additionally, the light-emitting diode (OLE) may further include a functional layer to improve the light-emitting efficiency and / or lifespan of the light-emitting layer (EL).

[0057] The cathode electrode (CAT) is laminated to make surface contact with the light-emitting layer (EL). The cathode electrode (CAT) is formed over the entire substrate (110) to be commonly connected to the light-emitting layer (EL) formed in all pixels. In the case of a bottom-emitting type, the cathode electrode (CAT) comprises a metallic material with excellent light reflection efficiency. For example, the cathode electrode (CAT) may be made of any one material selected from silver (Ag), aluminum (Al), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), or barium (Ba), or an alloy of two or more materials.

[0058] The display device according to this application does not have a separate in-cap layer on the light-emitting diode (OLE) because the cathode electrode (CAT) performs an in-cap function. To configure the cathode electrode (CAT) to have an in-cap function, it possesses a unique structural feature specific to this application.

[0059] In the display device according to this application, the cathode electrode (CAT) comprises at least two cathode electrode layers. Most preferably, it comprises three cathode electrode layers stacked in succession. For example, the cathode electrode (CAT) may have at least two of a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) sequentially stacked. Most preferably, it comprises all of the sequentially stacked first cathode electrode layer (CAT1), second cathode electrode layer (CAT2), and third cathode electrode layer (CAT3).

[0060] The first cathode electrode layer (CAT1) is first laminated to make direct surface contact with the light-emitting layer (EL). The first cathode electrode layer (CAT1) may include an inorganic material. For example, it may be formed from a metallic material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), or barium (Ba). Considering the manufacturing process and manufacturing cost, the case where the first cathode electrode layer (CAT1) is formed from aluminum is described as the most preferred example. When the first cathode electrode layer (CAT1) is formed from a metallic material, it is preferable to form it with a thickness of 100 Å to 3,000 Å. If it is thinner than 100 Å, the surface resistance of the cathode electrode (CAT) increases, making it difficult to maintain a stable common electrode. It may also be formed with a thickness of 3,000 Å or more, but if it is too thick, the manufacturing time increases and the manufacturing cost may rise.

[0061] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the barrier energy of the domain material. The resin material with high electron mobility may include any one selected from Alq3, TmPyPB, Bphen, TAZ, and TPB. Alq3 is an abbreviation for Tris(8-hydroxyquinoline) Aluminum, which is a complex having the chemical formula Al(C9H6NO)3. TmPyPB is an organic material an abbreviation for 1,3,5-tri(m-pyrid-3-yl-phenyl)benzene. Bphen is an organic material an abbreviation for Bathophenanthroline. TAZ is an organic material, and TPB is an organic material an abbreviation for triphenyl bismuth. These organic materials have high electron mobility and can be used in organic light-emitting diodes.

[0062] Dopant materials may include alkaline doping materials. For example, they may include any one of lithium (Li), cesium (Cs), cesium oxide (Cs2O3), cesium nitride (CsN3), rubidium (Rb), and rubidium oxide (Rb2O). Other dopant materials may include fullerenes, which possess high electron mobility characteristics. Fullerene is a general term for molecules in which carbon atoms are arranged in spherical, ellipsoidal, or cylindrical shapes. For example, Buckminsterfullerene (C), in which 60 carbon atoms are bonded in a soccer ball shape, is a type of fullerene. 60 ; May include Buckminster-fullerene). In addition, C 70 , C 76 , C 78 , C 82 , C 90 , C 94 and C 96 It may also include higher-order fullerenes such as.

[0063] The second cathode electrode layer (CAT2) may be made of the same material as the electron transport layer or electron injection layer included in the EL. However, unlike the electron transport layer or electron injection layer, it is desirable that the electron mobility be higher. For example, in the case of the electron transport layer or electron injection layer, the electron mobility is 5.0 × 10 -4 (S / m) to 9.0X10 -1 While (S / m) is the case, the second cathode electrode layer (CAT2) has an electron mobility of 1.0×10 -3 (S / m) to 9.0X10 +1 It is desirable that (S / m) is used. To this end, it is desirable that the conductive resin material constituting the second cathode electrode side (CAT2) has a higher dopant content than the electron transport layer or electron injection layer.

[0064] For example, it is preferable that the electron transport layer or electron injection layer is a conductive resin material in which the dopant doping concentration is 0% to 5%, whereas the second cathode electrode layer (CAT2) is a conductive resin material in which the dopant doping concentration is 3% to 30%. In particular, it is preferable that the doping concentration of the second cathode electrode layer (CAT2) is equal to or greater than that of the electron transport layer or electron injection layer. The domain material itself, with a dopant doping concentration of 0%, has an electrical conductivity of 1.0 x 10⁻¹⁰ -4 (S / m) to 5.0X10 -3 (S / m) may be. By injecting 3% to 30% of a dopant into the domain material, the second cathode electrode layer (CAT2) has an electrical conductivity of 1.0×10 -3 (S / m) to 9.0X10 +1 It is improved to (S / m) and can be used as a cathode electrode.

[0065] In some cases, the second cathode electrode layer (CAT2) may have the same conductivity as the electronic functional layer (electron transport layer and / or electron injection layer) of the light-emitting layer (EL). Even in this case, the total surface resistance of the cathode electrode (CAT) can be maintained at a sufficiently low value by the first cathode electrode layer (CAT1) made of a metallic material.

[0066] The third cathode electrode layer (CAT3) may include an inorganic material. In particular, when the third cathode electrode layer (CAT3) is laminated last, it is preferable to include a metal oxide material. For example, it may include any one of aluminum oxide (Al2O3), barium oxide (BaO), magnesium oxide (MgO), molybdenum oxide (MoO), or calcium oxide (CaO). When the first cathode electrode layer (CAT1) is formed of aluminum, considering the manufacturing process, it is preferable to form the third cathode electrode layer (CAT3) of aluminum oxide.

[0067] Metal oxide materials can prevent oxygen from penetrating from the outside. Therefore, it is preferable that the third cathode electrode layer (CAT3) be formed to completely cover the second cathode electrode layer (CAT2) and the first cathode electrode layer (CAT1) formed underneath it.

[0068] With reference to FIGS. 5 and 6, a specific stacked structure of a cathode electrode (CAT) applied over the entire area of ​​a substrate (110) will be described. FIG. 5 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along the dotted line I-I' of FIG. 1. FIG. 6 is a cross-sectional view showing the structure of an electroluminescent display device according to this application, cut along the dotted line III-III' of FIG. 1.

[0069] FIG. 5 is a cross-sectional view taken across the gate driver (200). Referring to FIG. 5, the electroluminescent display device according to this application includes thin-film transistors (ST, DT) formed on a substrate (110). A protective film (PAS) is applied over the thin-film transistors (ST, DT). The protective film (PAS) is laminated to cover the entire surface of the substrate (110). A planarization film (PL) is applied over the protective film (PAS). The planarization film (PL) may be formed of an organic material to flatten the surface of the substrate (110), which has become rough as the thin-film transistors (ST, DT) are formed. Since organic materials are susceptible to moisture or oxygen, it is preferable to form it only in the display area (DA). Alternatively, as shown in FIG. 5, a structure is illustrated in which the planarization film (PL) extends from the display area (DA) to the gate driver (200). In any case, it is preferable that the flattening film (PL) be laminated so as not to cover the entire surface of the substrate (110).

[0070] A light-emitting diode (OLE) is formed on the planarization film (PL). It is preferable that the light-emitting layer (EL) be laminated with an area corresponding to the display area (DA). In some cases, the light-emitting layer (EL) may have a size slightly larger than the display area (DA). Meanwhile, a cathode electrode (CAT) is laminated on the light-emitting layer (EL) to completely cover the light-emitting layer (EL) with an area larger than that of the light-emitting layer (EL). The cathode electrode (CAT) is formed by sequentially laminating a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3).

[0071] The first cathode electrode layer (CAT1) can be formed to completely cover the light-emitting layer (EL). For example, the first cathode electrode layer (CAT1) can be laminated with an area larger than the area of ​​the light-emitting layer (EL) to completely cover the end of the light-emitting layer (EL). Additionally, it is preferable that the first cathode electrode layer (CAT1) be formed to completely cover the planarization film (PL). For example, the light-emitting layer (EL) can be applied with an area smaller than that of the planarization film (PL) while covering the entire display area (DA). The first cathode electrode layer (CAT1) can be laminated to completely cover the vertical plane at the end of the planarization film (PL) and to have a cross-sectional profile that is in surface contact with the upper surface of the protective film (PAS) exposed outside the planarization film (PL).

[0072] The second cathode electrode layer (CAT2), particularly when the second cathode electrode layer (CAT2) is formed of a conductive resin material, can be laminated over the first cathode electrode layer (CAT1) with an area smaller than that of the planarization film (PL), as shown in FIG. 5. As another example, the second cathode electrode layer (CAT2) can be formed to have an area larger than that of the first cathode electrode layer (CAT1) and to completely cover the end of the first cathode electrode layer (CAT1).

[0073] The third cathode electrode layer (CAT3) may be formed to completely cover the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2). For example, the third cathode electrode layer (CAT3) may be laminated with an area larger than that of the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2) so as to completely cover the ends of the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2). For example, if the second cathode electrode layer (CAT2) is formed with a smaller size than the first cathode electrode layer (CAT1), it is preferable that the third cathode electrode layer (CAT3) be formed to completely cover the first cathode electrode layer (CAT1). As another example, if the second cathode electrode layer (CAT2) is formed to completely cover the first cathode electrode layer (CAT1), it is preferable that the third cathode electrode layer (CAT3) be formed to completely cover the second cathode electrode layer (CAT2).

[0074] As shown in FIG. 5, the planarization film (PL) can be positioned to cover the gate driver (200). Additionally, among the cathode electrodes (CAT), the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3) can be extended to completely cover the gate driver (200). In some cases, the planarization film (PL) may be applied only up to the gate driver (200). In this case, the gate driver (200) has a structure covered only by a protective film (PAS). In this case, the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3) may cover the gate driver (200) or may be positioned so as not to cover the gate driver (200). For device protection, it is preferable for the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3) to cover the gate driver (200).

[0075] Next, the description refers to FIG. 6. FIG. 6 is a cross-sectional view taken across the data pad portion (300). Referring to FIG. 6, the electroluminescent display device according to this application includes thin-film transistors (ST, DT) formed on a substrate (110). A protective film (PAS) is applied over the thin-film transistors (ST, DT). The protective film (PAS) is laminated to cover the entire surface of the substrate (110). A flattening film (PL) is applied over the protective film (PAS). The flattening film (PL) may be formed from an organic material to flatten the surface of the substrate (110), which has become rough as the thin-film transistors (ST, DT) are formed. Since the flattening film (PL) made of an organic material is susceptible to moisture or oxygen, it may be formed only in the display area (DA). On the other hand, since the protective film (PAS) made of an inorganic material has excellent performance in blocking the penetration of moisture and oxygen, it is preferable to laminate it over the entire surface of the substrate (110).

[0076] A light-emitting diode (OLE) is formed on the planarization film (PL). In particular, the cathode electrode (CAT) has a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) sequentially stacked.

[0077] A pad electrode (301) is disposed in the data pad section (300). The pad electrode (301) is covered by a gate insulating film (GI) and a protective film (PAS), and the central portion is exposed by a pad contact hole (H). The pad electrode (301) may be disposed on the same layer as the gate electrodes. A pad terminal (303) is formed on the pad electrode (301). The pad terminal (303) is formed on the protective film (PAS) and is connected to the pad electrode (301) by the pad contact hole (H). The pad terminal (303) may be formed of the same material as the source-drain electrodes or the anode electrode.

[0078] The pad electrode (301) may include a data pad electrode, a driving current pad electrode, and a low power pad electrode. The data pad electrode may be placed at the end of the data wiring (DL). The driving current pad electrode may be placed at the end of the driving current wiring (VDD). The low power pad electrode may be placed at the end of the low power wiring (VSS).

[0079] The pad terminal (303) may include a data pad terminal corresponding to a data pad electrode, a driving current pad terminal corresponding to a driving current pad electrode, and a low power pad terminal corresponding to a low power pad electrode. The pad terminal (303) may be formed in an independent island shape corresponding to the pad electrode (301). Although not shown in the drawing, the low power pad terminal may be connected to a cathode electrode (CAT) to receive low power.

[0080] In FIG. 6, the first cathode electrode layer (CAT1) is formed to completely cover the light-emitting layer (EL). For example, the light-emitting layer (EL) may cover the entire display area (DA) but may be applied over an area smaller than that of the planarization film (PL). The first cathode electrode layer (CAT1) completely covers the vertical plane at the end portion of the planarization film (PL) and may be laminated to make surface contact with the upper surface of the protective film (PAS) exposed outside the planarization film (PL).

[0081] The second cathode electrode layer (CAT2) may be formed to have a larger area than the first cathode electrode layer (CAT1) and to completely cover the end of the first cathode electrode layer (CAT1). As another example, the second cathode electrode layer (CAT2) may be laminated with a smaller area than the first cathode electrode layer (CAT1). FIG. 6 illustrates a second cathode electrode (CAT2) laminated with a larger area than the first cathode electrode layer (CAT1).

[0082] The third cathode electrode layer (CAT3) can be formed to completely cover the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2). For example, the third cathode electrode layer (CAT3) can be laminated with an area larger than that of the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2) so as to completely cover the ends of the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2). As shown in FIG. 6, when the second cathode electrode layer (CAT2) is formed to completely cover the first cathode electrode layer (CAT1), it is preferable that the third cathode electrode layer (CAT3) be formed to completely cover the second cathode electrode layer (CAT2). As another example, if the second cathode electrode layer (CAT2) is formed with a smaller size than the first cathode electrode layer (CAT1), it is preferable that the third cathode electrode layer (CAT3) be formed to completely cover the first cathode electrode layer (CAT1).

[0083] In this way, the third cathode electrode layer (CAT3) can be laminated to completely cover the ends of the second cathode electrode layer (CAT2) and the first cathode electrode layer (CAT3) and to extend further outward. Since the third cathode electrode layer (CAT3) is formed to completely cover all thin film layers formed underneath it, it can perform an in-cap function that prevents oxygen or foreign substances from penetrating from the outside.

[0084] Additionally, the cathode electrode (CAT) has a structure in which a protective film (PAS) is exposed on the outside. Since the protective film (PAS) is formed of an inorganic material, it can prevent oxygen or moisture from penetrating from the outside. The cathode electrode (CAT) has a structure that completely seals all thin films formed of organic materials on the substrate (110), thereby ensuring sufficient in-cap functionality.

[0085] Metal oxide materials can have electron mobility values ​​that are very low compared to metal materials. For example, aluminum oxide is known as an insulator. However, if aluminum oxide is formed with a thickness of 200 Å or less, it can easily overcome the work function barrier that hinders electron movement, thereby possessing conductive characteristics and being usable as a common electrode. Additionally, if the thickness of the metal oxide material is thinner than 10 Å, the thin film layer may not be formed uniformly over the entire surface and may be stacked in a separated island shape. Consequently, the metal oxide material may not be coated over the entire surface, and thus may fail to prevent oxygen or foreign substances from penetrating from the outside. Therefore, when forming the third cathode electrode layer (CAT3) with a metal oxide material, it is preferable that its thickness be between 10 Å and 200 Å.

[0086] In summary, the cathode electrode (CAT) according to this application may have a structure in which at least two of the first cathode electrode layer (CAT1), the second cathode electrode layer (CAT2), and the third cathode electrode layer (CAT3) are continuously stacked. These, the first cathode electrode layer (CAT1), the second cathode electrode layer (CAT2), and the third cathode electrode layer (CAT3) are all composed of conductive thin film layers. The metal material included in the cathode electrode (CAT) preferably includes a metal material such as aluminum, which has a relatively low sheet resistance. The metal oxide material included in the cathode electrode (CAT) preferably has a thickness of 10 Å to 200 Å to ensure electron mobility. In addition, the conductive resin material included in the cathode electrode (CAT) preferably has an electron mobility higher than that of the electron transport layer and the electron injection layer included in the light-emitting layer (EL). To this end, it is preferable that the conductive resin material contains an alkali metal dopant at a doping concentration of 3% to 30% in a main resin material having high electron mobility.

[0087] In some cases, the doping concentration of the conductive resin material can be set to the same level as that of the electronic functional layer included in the light-emitting layer. In this case, it is desirable to stack the thickness of the first cathode electrode layer (CAT1) containing a metal material to at least 500 Å to 3,000 Å, and to set the sheet resistance of the entire cathode electrode (CAT) to match the conditions of the cathode electrode.

[0088] In the foregoing, the most basic and desirable structure of the electroluminescent display device according to this application has been described as an example. Hereinafter, with reference to the drawings, embodiments of various stacked structures of the cathode electrode (CAT) in the display device according to this application will be described.

[0089] <1st Embodiment>

[0090] With reference to FIGS. 7a and 7b, the structure of a display device according to the first embodiment of this application will be described. For convenience of explanation, the description will focus on the light-emitting diode (OLE). FIGS. 7a and 7b are cross-sectional views showing the stacked structure of the light-emitting diode in an electroluminescent display device according to the first embodiment of this application.

[0091] First, referring to FIG. 7a, the light-emitting diode according to the first embodiment of this application has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1) and a second cathode electrode layer (CAT2) are sequentially stacked.

[0092] The first cathode electrode layer (CAT1) may include a metallic material. For example, the first cathode electrode layer (CAT1) may include a metallic material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The first cathode electrode layer (CAT1) may have a thickness of 100 Å to 3,000 Å.

[0093] The second cathode electrode layer (CAT2) may include a metal oxide material. For example, the second cathode electrode layer (CAT2) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The second cathode electrode layer (CAT2) may have a thickness of 10 Å to 200 Å. Here, it is preferable that the first cathode electrode layer (CAT1) formed from a metal material is thicker than the thickness of the second cathode electrode layer (CAT2) formed from a metal oxide material.

[0094] Next, referring to FIG. 7b, the light-emitting diode according to the first embodiment of this application has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1) and a second cathode electrode layer (CAT2) are sequentially stacked.

[0095] The first cathode electrode layer (CAT1) may include a metal oxide material. For example, the first cathode electrode layer (CAT1) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The first cathode electrode layer (CAT1) may have a thickness of 10 Å to 200 Å.

[0096] The second cathode electrode layer (CAT2) may include a metallic material. For example, the second cathode electrode layer (CAT2) may include a metallic material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The second cathode electrode layer (CAT2) may have a thickness of 100 Å to 3,000 Å. Preferably, it may have a thickness of 500 Å to 2,000 Å. In particular, it is preferable that the first cathode electrode layer (CAT1) formed from a metallic material is thicker than the thickness of the second cathode electrode layer (CAT2) formed from a metallic oxide material.

[0097] In the first embodiment, the second cathode electrode layer (CAT2) is formed at the very top, and subsequently, no in-cap layer or additional thin film layer having an in-cap function thereon is disposed therein. However, additional functional elements for other purposes may be disposed therein. For example, additional elements bonded using an adhesive layer, rather than a functional layer that is continuously deposited or continuously coated, may be disposed therein.

[0098] The second cathode electrode layer (CAT2) is formed at the very top and is preferably formed to completely cover the first cathode electrode layer (CAT1). As described in FIGS. 5 and 6, the first cathode electrode layer (CAT1) covers the entire display area (DA) and can be applied extending to the non-display area (NDA). Additionally, it is preferable that the first cathode electrode layer (CAT1) be formed to completely cover the light-emitting layer (EL) formed underneath it. That is, it is preferable that the first cathode electrode layer (CAT1) covers the end of the light-emitting layer (EL) and makes surface contact with the thin film layer placed beneath the light-emitting layer (EL).

[0099] It is preferable that the second cathode electrode layer (CAT2) completely covers the display area (DA) and extends to the non-display area (NDA), and in particular, is formed to completely cover the first electrode layer (CAT1) and the light-emitting layer (EL) with an area larger than that of the first electrode layer (CAT1). That is, it is preferable that the second cathode electrode layer (CAT2) covers the end of the first cathode electrode layer (CAT1) and makes surface contact with the thin film layer exposed outside the end of the first cathode electrode layer (CAT1).

[0100] <Second Embodiment>

[0101] Hereinafter, with reference to FIG. 8, the structure of an electroluminescent display device according to the second embodiment of this application will be described. For convenience of explanation, the description will focus on the electroluminescent diode (OLE). FIG. 8 is a cross-sectional view showing the stacked structure of the light-emitting diode in the electroluminescent display device according to the second embodiment of this application.

[0102] Referring to FIG. 8, the electroluminescent display device according to the second embodiment has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1) and a second cathode electrode layer (CAT2) are sequentially stacked.

[0103] The first cathode electrode layer (CAT1) has a structure in which a metal oxide layer (10) and a metal layer (20) are continuously stacked. For example, the metal oxide layer (10) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The metal layer (20) may include a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba).

[0104] For example, the first cathode electrode layer (CAT1) may have a structure in which a metal oxide layer (10) made of aluminum oxide and a metal layer (20) made of aluminum are sequentially stacked. The metal oxide layer (10) made of aluminum oxide may have a thickness of 10 Å to 200 Å. The metal layer (20) made of aluminum may have a thickness of 100 Å to 3,000 Å. As explained above, since aluminum oxide has a relatively thin thickness of 10 Å to 200 Å, it can easily overcome the electron transport barrier and thus can be used as a conductive layer. In particular, it is preferable that the metal layer (20) formed from a metal material be thicker than the thickness of the metal oxide layer (10) formed from a metal oxide material.

[0105] The second cathode electrode layer (CAT2) may have the same stacked structure as the first cathode electrode layer (CAT1). That is, the second cathode electrode layer (CAT2) has a structure in which the metal oxide layer (10) and the metal layer (20) are continuously stacked.

[0106] As another example, although not illustrated in the drawing, the first cathode electrode layer (CAT1) may be stacked with the stacking order of the metal layer (20) and the metal oxide layer (10) reversed. Additionally, the second cathode electrode layer (CAT2) may also be stacked with the stacking order of the metal layer (20) and the metal oxide layer (10) reversed.

[0107] In the second embodiment, the order in which the metal oxide layer (10) and the metal layer (20) are stacked in the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2) can be formed in various ways. However, in any case, it is preferable that the first cathode electrode layer (CAT1) be stacked with an area larger than the light-emitting layer (EL) so as to completely cover the light-emitting layer (EL). Additionally, it is preferable that the second cathode electrode layer (CAT2), which is stacked at the very top, be stacked with an area larger than the first cathode electrode layer (CAT2) so as to completely cover the first cathode electrode layer (CAT1).

[0108] <Third Embodiment>

[0109] Referring to FIG. 9, the structure of a display device according to the third embodiment of this application will be described. FIG. 9 is a cross-sectional view showing the stacked structure of light-emitting diodes in an electroluminescent display device according to the third embodiment of this application.

[0110] Referring to FIG. 9, the electroluminescent display device according to the third embodiment has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) are sequentially stacked.

[0111] The first cathode electrode layer (CAT1) has a structure in which a lower metal oxide layer (11), a metal layer (20), and an upper metal oxide layer (30) are continuously stacked. For example, the lower metal oxide layer (11) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The metal layer (20) may include a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The upper metal oxide layer (30) may include the same material as the lower metal oxide layer (11).

[0112] For example, the first cathode electrode layer (CAT1) may have a structure in which a lower metal oxide layer (11) made of aluminum oxide, a metal layer (20) made of aluminum, and an upper metal oxide layer (30) made of aluminum oxide are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30) made of metal oxide material may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 500 Å to 5,000 Å. In particular, it is preferable that the metal layer (20) formed of metal material is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30) formed of metal oxide material.

[0113] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the work function barrier energy. The resin material with high electron mobility, which is the domain material, may include any one selected from Alq3, TmPyPB, Bphen, TAZ, and TPB.

[0114] Dopant materials may include alkaline doping materials. For example, they may include any one of lithium (Li), cesium (Cs), cesium oxide (Cs2O3), cesium nitride (CsN3), rubidium (Rb), and rubidium oxide (Rb2O). Other dopant materials include fullerene (C), in which 60 carbon atoms with high electron mobility are bonded in a soccer ball shape. 60 It may include ).

[0115] The third cathode electrode layer (CAT3) may have the same stacked structure as the first cathode electrode layer (CAT1). For example, the third cathode electrode layer (CAT3) may have a structure in which a lower metal oxide layer (11) made of aluminum oxide, a metal layer (20) made of aluminum, and an upper metal oxide layer (30) made of aluminum oxide are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30) made of metal oxide material may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20) formed of the metal material is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30) formed of the metal oxide material.

[0116] For example, the metal layer (20) may have a thickness of 500 Å, and the lower and upper metal oxide layers (11, 30) may have a thickness of 50 Å. Additionally, the second cathode electrode layer (CAT2) may include a conductive resin material and may be formed with a thickness of 2 μm to 4 μm. The second cathode electrode layer (CAT2) may be interposed between the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3), which are made only of inorganic material, to relieve stress between the inorganic thin film layers, thereby preventing the cathode electrode (CAT) from being damaged.

[0117] Although not illustrated in the drawings, the first cathode electrode layer (CAT1) may have a structure in which a lower metal layer, a metal oxide layer, and an upper metal layer are sequentially stacked. Additionally, the third cathode electrode layer (CAT3) may also have a structure in which a lower metal layer, a metal oxide layer, and an upper metal layer are sequentially stacked. That is, the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3) may have the same stacked structure or different stacked structures.

[0118] <Fourth Embodiment>

[0119] Hereinafter, with reference to FIG. 10, the structure of an electroluminescent display device according to the fourth embodiment of this application will be described. FIG. 10 is a cross-sectional view showing the stacked structure of light-emitting diodes in an electroluminescent display device according to the fourth embodiment of this application.

[0120] Referring to FIG. 10, the electroluminescent display device according to the fourth embodiment has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) are sequentially stacked.

[0121] The first cathode electrode layer (CAT1) has a structure in which a metal oxide layer (10) and a metal layer (20) are continuously stacked. For example, the lower metal oxide layer (10) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The metal layer (20) may include a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba).

[0122] For example, the first cathode electrode layer (CAT1) may have a structure in which a metal oxide layer (10) made of aluminum oxide and a metal layer (20) made of aluminum are sequentially stacked. The metal oxide layer (10) made of a metal oxide material may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20) formed of a metal material be thicker than the thickness of the metal oxide layer (10) formed of a metal oxide material.

[0123] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the work function film energy. The resin material with high electron mobility, which is the domain material, may include any one selected from Alq3, TmPyPB, Bphen, TAZ, and TPB.

[0124] Dopant materials may include alkaline doping materials. For example, they may include any one of lithium (Li), cesium (Cs), cesium oxide (Cs2O3), cesium nitride (CsN3), rubidium (Rb), and rubidium oxide (Rb2O). Other dopant materials include fullerene (C), in which 60 carbon atoms are bonded in a soccer ball shape. 60 It may include ).

[0125] The third cathode electrode layer (CAT3) may have a structure in which it is stacked inversely with the first cathode electrode layer (CAT1). For example, the third cathode electrode layer (CAT3) may have a structure in which a metal layer (20) made of aluminum and a metal oxide layer (10) made of aluminum oxide are sequentially stacked. It is preferable that the metal oxide layer (10) made of the metal oxide material has a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20) formed from the metal material is thicker than the thickness of the metal oxide layer (10) formed from the metal oxide material.

[0126] The second cathode electrode layer (CAT2) may include a conductive resin material and be formed with a thickness of 2 μm to 4 μm. The second cathode electrode layer (CAT2) may be interposed between the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3), which are made only of inorganic material, to relieve stress between the inorganic thin film layers, thereby preventing the cathode electrode (CAT) from being damaged.

[0127] Although not illustrated in the drawing, the first cathode electrode layer (CAT1) may have a structure in which a metal layer (20) and a metal oxide layer (10) are sequentially stacked. Additionally, the third cathode electrode layer (CAT3) may have a structure in which a metal oxide layer (10) and a metal layer (20) are sequentially stacked. That is, the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3) may have the same stacked structure or different stacked structures.

[0128] <5th Embodiment>

[0129] Hereinafter, with reference to FIG. 11, the structure of an electroluminescent display device according to the fifth embodiment of this application will be described. FIG. 11 is a cross-sectional view showing the stacked structure of light-emitting diodes in an electroluminescent display device according to the fifth embodiment of this application.

[0130] Referring to FIG. 11, the electroluminescent display device according to the fifth embodiment has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) are sequentially stacked.

[0131] The first cathode electrode layer (CAT1) has a structure in which a metal oxide layer (10) and a metal layer (20) are continuously stacked. For example, the metal oxide layer (10) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The metal layer (20) may include a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba).

[0132] For example, the first cathode electrode layer (CAT1) may have a structure in which a metal oxide layer (10) made of aluminum oxide and a metal layer (20) made of aluminum are sequentially stacked. The metal oxide layer (10) made of a metal oxide material may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20) formed of a metal material be thicker than the thickness of the metal oxide layer (10) formed of a metal oxide material.

[0133] The second cathode electrode layer (CAT2) may have the same stacked structure as the first cathode electrode layer (CAT1). For example, the second cathode electrode layer (CAT2) has a structure in which a metal oxide layer (10) and a metal layer (20) are continuously stacked. The metal oxide layer (10), made of a metal oxide material, may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20), formed of a metal material, is thicker than the thickness of the metal oxide layer (10), formed of a metal oxide material.

[0134] The third cathode electrode layer (CAT3) may have the same stacked structure as the first cathode electrode layer (CAT1). For example, the third cathode electrode layer (CAT3) has a structure in which a metal oxide layer (10) and a metal layer (20) are continuously stacked.

[0135] Although not illustrated in the drawings, the stacking structure of the first cathode electrode layer (CAT1) and the second cathode electrode layer (CAT2) may be different. Additionally, the stacking structure of the third cathode electrode layer (CAT3) may be different from that of the first cathode electrode layer (CAT1) or the second cathode electrode layer (CAT3).

[0136] <6th Embodiment>

[0137] Hereinafter, the structure of an electroluminescent display device according to the 6th embodiment of this application will be described with reference to FIG. 12. FIG. 12 is a cross-sectional view showing the stacked structure of light-emitting diodes in an electroluminescent display device according to the 6th embodiment of this application.

[0138] Referring to FIG. 12, the electroluminescent display device according to the 6th embodiment has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) are sequentially stacked.

[0139] The first cathode electrode layer (CAT1) may have a single-layer structure including a metal oxide material. For example, the first cathode electrode layer (CAT1) may include a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO).

[0140] For example, the first cathode electrode layer (CAT1) may have a single-layer structure made of aluminum oxide. The first cathode electrode layer (CAT1) made of a metal oxide material may have a thickness of 10 Å to 200 Å.

[0141] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the work function film energy. The resin material with high electron mobility, which is the domain material, may include any one selected from Alq3, TmPyPB, Bphen, TAZ, and TPB.

[0142] Dopant materials may include alkaline doping materials. For example, they may include any one of lithium (Li), cesium (Cs), cesium oxide (Cs2O3), cesium nitride (CsN3), rubidium (Rb), and rubidium oxide (Rb2O). Other dopant materials may include fullerenes having high electron mobility characteristics. For example, a fullerene (C) in which 60 carbon atoms are bonded in a soccer ball shape. 60 It may include ).

[0143] The third cathode electrode layer (CAT3) may have a structure in which a lower metal oxide layer (11) made of aluminum oxide, a metal layer (20) made of aluminum, and an upper metal oxide layer (30) made of aluminum oxide are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30) made of metal oxide material may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20) formed of metal material is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30) formed of metal oxide material.

[0144] The second cathode electrode layer (CAT2) may include a conductive resin material and be formed with a thickness of 2 μm to 4 μm. The second cathode electrode layer (CAT2) may be interposed between the first cathode electrode layer (CAT1) and the third cathode electrode layer (CAT3), which are made only of inorganic material, to relieve stress between the inorganic thin film layers, thereby preventing the cathode electrode (CAT) from being damaged.

[0145] Although not illustrated in the drawings, the third cathode electrode layer (CAT3) may have a structure in which a lower metal layer, a metal oxide layer, and an upper metal layer are sequentially stacked. In this case, the lower metal layer and the upper metal layer may each have a thickness of 100 Å to 3,000 Å, and the metal oxide layer may have a thickness of 10 Å to 200 Å. In particular, it is preferable that the upper metal layer and the lower metal layer formed from a metal material are thicker than the thickness of the metal oxide layer formed from a metal oxide material.

[0146] The electroluminescent display device according to the above-described application comprises an electroluminescent diode in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) not only functions as a common electrode to receive a common voltage but also has an in-cap function to prevent oxygen or foreign substances from penetrating into the light-emitting layer (EL) from the outside. To this end, the cathode electrode (CAT) has a structure in which a plurality of conductive layers are sequentially stacked. The cathode electrode (CAT) includes a metal layer with excellent conductivity. To maintain a low sheet resistance value of the cathode electrode (CAT), the metal layer is formed with a thickness of 100 Å to 3,000 Å, preferably with a thickness of 500 Å or more. The cathode electrode (CAT) includes a metal oxide layer for the in-cap function. Since the metal oxide layer must also function as a conductive layer, it is preferable for it to have a thin thickness of 10 Å to 200 Å. In addition, the cathode electrode (CAT) includes a relatively thick and highly elastic resin material with a thickness of 2 to 4 μm to prevent the cathode electrode from being damaged by external force. In particular, since the resin material must function as a conductive layer, it is composed of a domain resin material with high electron mobility and a conductive resin material containing an alkali metal dopant to enhance electron mobility.

[0147] The embodiments described so far have been explained as basic structures among various stacked structures of conductive layers constituting the cathode electrode. However, they are not limited thereto, and a cathode electrode with a multilayer structure can be constructed by combining two or more embodiments. For example, the cathode electrode can be constructed to have a complex stacked structure by adding a stacked structure according to any one of the second to sixth embodiments to the stacked structure according to the first embodiment.

[0148] <7th Embodiment>

[0149] The above embodiments focused on cases where the cathode electrode has a multilayer structure capable of performing an in-cap function. Below, a case will be described where the cathode electrode has a triple-layer stacked structure and additionally includes a function to suppress external light reflection.

[0150] FIG. 13 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to the 7th embodiment of this application. Referring to FIG. 13, the electroluminescent display device according to the 7th embodiment of this application has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked.

[0151] In particular, the cathode electrode (CAT) comprises three cathode electrode layers stacked in succession. For example, the cathode electrode (CAT) comprises a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) stacked in succession.

[0152] The first cathode electrode layer (CAT1) is formed from a metal material with low sheet resistance, such as aluminum (Al), silver (Ag), molybdenum (Mo), or gold (Au). For example, the first cathode electrode layer (CAT1) can be formed from aluminum with a thickness of 100 Å to 200 Å.

[0153] The second cathode electrode layer (CAT2) can be formed from a conductive resin material. The second cathode electrode layer (CAT2) can be made of the same material as the electron transport layer or electron injection layer included in the light-emitting layer (EL). It is preferable that the second cathode electrode layer (CAT2) be a conductive resin material having a doping concentration of 3% to 30% of a dopant. For example, the second cathode electrode layer (CAT2) can be formed from a conductive resin material having a thickness of 500 Å to 900 Å.

[0154] It is preferable that the third cathode electrode layer (CAT3) be formed with a metal material having a low sheet resistance and a relatively thicker thickness than the first and second cathode electrode layers (CAT1, CAT2) in order to lower the sheet resistance of the entire cathode electrode (CAT). For example, the third cathode electrode layer (CAT3) can be formed of aluminum having a thickness of at least 2,000 Å.

[0155] A cathode electrode layer (CAT) having such thickness and stacked structure can minimize the reflectance of light incident from the lower direction (first cathode electrode layer (CAT1)). Referring to the arrows indicating the light paths illustrated in FIG. 13,

[0156] Incident light (①) entering from the bottom of the cathode electrode (CAT) passes through the transparent anode electrode (ANO) and the light-emitting layer (EL), is partially reflected from the bottom surface of the first cathode electrode layer (CAT1), and proceeds toward the substrate (SUB) as primary reflected light (②). Since the first cathode electrode layer (CAT1) has a thin thickness of 200 Å or less, it cannot reflect all of the incident light (①). For example, only about 40% of the incident light (①) is reflected as primary reflected light (②), and the remaining 60% passes through the first cathode electrode layer (CAT1). The transmitted light (③) that passes through the first cathode electrode layer (CAT1) passes through the transparent second cathode electrode layer (CAT2) as is. After that, the transmitted light (③) is reflected by the third cathode electrode layer (CAT3). Since the third cathode electrode layer (CAT3) has a thickness of 2,000 Å or more, all of the transmitted light (③) is reflected and travels toward the substrate (SUB) as secondary reflected light (④).

[0157] At this time, the thickness of the second cathode electrode layer (CAT2) can be adjusted so that the phases of the first reflected light (②) and the second reflected light (④) cancel each other out. As a result, the luminance of the reflected light, which is the intensity of the reflected light incident and reflected from the bottom of the cathode electrode (CAT), can be reduced to 2%.

[0158] Meanwhile, among the light emitted from the emitting layer (EL), the light radiated in the direction of the cathode electrode (CAT) may also be reduced to about 2% as it is emitted in the direction of the substrate (SUB) through the same optical path. However, since the light emitted from the emitting layer (EL) is emitted in all directions, the amount of light reduced by the cathode electrode (CAT) is only about 50% of the total amount of light, and the remaining 50% is emitted in the direction of the substrate (SUB).

[0159] The electroluminescent display device according to the 7th embodiment may be a bottom-emitting type having a cathode electrode with a triple-layer stacked structure. In addition, the reflectivity of external light can be suppressed to the maximum extent by the structure of the cathode electrode with a triple-layer stacked structure. Therefore, there is no need to place a polarizing element to reduce external light reflection outside the substrate (SUB). Although the polarizing element has a positive effect of suppressing external light reflection, it has a negative effect of reducing the amount of light emitted from the light-emitting layer (EL) by at least 50%.

[0160] In the electroluminescent display device according to the 7th embodiment, the amount of light emitted from the light-emitting layer (EL) is reduced by about 50% due to the cathode electrode of the triple-layer stacked structure, but this is almost the same as the reduction in the amount of light caused by the polarizing element. Therefore, the electroluminescent display device according to this application can minimize external light reflection while providing the same level of light-emitting efficiency of the light-emitting layer (EL) without using an expensive polarizing element.

[0161] Additionally, if necessary, the cathode electrode (CAT) according to the 7th embodiment may further include a composite structure such as that of the 2nd to 6th embodiments.

[0162] <8th Embodiment>

[0163] In the seventh embodiment, by having a triple-layer stacked structure on the cathode electrode, the effect of suppressing external light reflection by the cathode electrode is further provided. In the eighth embodiment with reference to FIG. 14, a structure is described for suppressing external light reflection by metallic wiring, such as gate wiring or data wiring, in addition to suppressing external light reflection by the cathode electrode in a bottom-emitting electroluminescent display device. FIG. 14 is a cross-sectional view showing the structure of an electroluminescent display device according to the eighth embodiment of this application.

[0164] FIG. 14 illustrates a bottom-emitting electroluminescent display device equipped with a top-gate structure thin-film transistor according to the present application. In FIG. 14, for convenience, only a driving thin-film transistor (DT) is shown. It is not limited thereto and may also include a switching thin-film transistor as shown in FIG. 4.

[0165] A light-blocking layer (LSD) is disposed on the substrate (SUB). The light-blocking layer (LSD) may be a light-blocking material for protecting the driving semiconductor layer (DA) of the driving thin-film transistor (DT) from external light. Additionally, the light-blocking layer (LSD) may be used as a data line or a driving current line (VDD). In this case, the light-blocking layer (LSD) is connected to the driving source electrode (DS) of the driving thin-film transistor (DT).

[0166] The light-blocking layer (LSD) may be positioned to overlap the driving semiconductor layer (DA) to prevent the influence of external light incident on the driving semiconductor layer (DA) from outside the substrate (SUB). The light-blocking layer (LSD) may be used as a driving current wiring (VDD) connected to the driving source electrode (DS) of the driving thin-film transistor (DT). To this end, it is preferable that the light-blocking layer (LSD) comprises a metallic material including copper (Cu).

[0167] If the light-blocking layer (LSD) is a metallic material, external light incident from outside the substrate (SUB) is reflected by the light-blocking layer (LSD), causing the user to perceive the reflected light and potentially degrading display quality. To prevent this, it is desirable to apply a low-reflection metal layer structure to the light-blocking layer (LSD).

[0168] For example, the light-blocking layer (LSD) may have a triple-layer structure. The light-blocking layer (LSD) comprises a first layer (L1), a second layer (L2), and a third layer (L3) stacked sequentially. The first layer (L1) may be formed of tantalum (Ta) having a thickness of 100 Å to 200 Å. The second layer (L2) may be formed of molybdenum oxide (MoOx) having a thickness of 500 Å to 900 Å. Molybdenum oxide is transparent. The third layer (L3) may include a metal material with low sheet resistance, such as copper (Cu), having a thickness of at least 2,000 Å. The third layer (L3) may also be formed as a double metal layer in which copper and molybdenum-titanium are stacked.

[0169] Although not illustrated in the drawings, as another example, the light-blocking layer (LSD) may have a double-layer structure. In this case, the light-blocking layer may include a first layer and a second layer stacked sequentially. The first layer located at the bottom may be composed of a metal oxide layer having a thickness of 500 Å to 900 Å, and the second layer located at the top may be composed of a metal material with low sheet resistance, such as copper (Cu), having a thickness of at least 2,000 Å. Specifically, the first layer may be formed of a material such as transparent molybdenum-titanium oxide (MoTiOx), molybdenum-tantalum oxide (MoOx:Ta), tungsten oxide (WOx), and molybdenum-copper oxide (MoCuOx). Additionally, the second layer may be composed of a single metal layer made of copper, or a double metal layer in which copper and molybdenum-titanium (MoTi) are stacked.

[0170] A buffer layer (BUF) is laminated on the light-blocking layer (LSD). A thin-film transistor is formed on the buffer layer (BUF). The thin-film transistor includes a switching thin-film transistor (not shown) and a driving thin-film transistor (DT). A protective film (PAS) is laminated on the substrate (SUB) on which the thin-film transistor is formed. A color filter (CF) is formed on the protective film (PAS). It is preferable to position the color filter (CF) so as to completely overlap with the light-emitting diode (OLE) that is subsequently formed. In some cases, the color filter (CF) may have a larger size than the light-emitting diode (OLE). A planarization film (PL) is coated on the color filter (CF). A light-emitting diode (OLE) is formed on the planarization film (PL).

[0171] In this way, the light-blocking layer (LSD) can have the same structure as the cathode electrode (CAT) described in the 7th embodiment. That is, it has the common feature of a thin metal layer, a transparent conductive layer, and a thick metal layer being sequentially stacked. Therefore, the reflectance of light incident from the outside can be minimized to the 2% level in the same manner as the optical path described in the 7th embodiment.

[0172] Additionally, although not illustrated in the drawing, the gate wiring (GL) may also have a low-reflection structure similar to the light-blocking layer (LSD). The driving gate electrode (DG) and the switching gate electrode (SG) may have a structure covered by the light-blocking layer (LSD). However, since the gate wiring (GL) is orthogonal to the light-blocking layer (LSD) used for the data wiring (DL) and driving current wiring (VDD), a large portion of it is not covered by the light-blocking layer (LSD) and remains exposed. Consequently, external light may be reflected by the gate wiring (GL), which can degrade the display quality. To prevent this, the gate wiring (GL) may also have a triple-layer structure similar to the light-blocking layer (LSD).

[0173] For example, the gate wiring (GL) includes a first layer (L1), a second layer (L2), and a third layer (L3) stacked sequentially. The first layer (L1) may be formed of tantalum (Ta) having a thickness of 100 Å to 200 Å. The second layer (L2) may be formed of molybdenum oxide (MoOx) having a thickness of 500 Å to 900 Å. Molybdenum oxide is transparent. The third layer (L3) may include a metal material with low sheet resistance, such as copper (Cu), having a thickness of at least 2,000 Å. The third layer (L3) may also be formed as a double metal layer stacked with copper and molybdenum-titanium.

[0174] Although not illustrated in the drawings, as another example, the gate wiring may have a double-layer structure. In this case, the gate wiring may include a first layer and a second layer stacked sequentially. The first layer located at the bottom may be composed of a metal oxide layer having a thickness of 500 Å to 900 Å, and the second layer located at the top may be composed of a metal material with low sheet resistance, such as copper (Cu), having a thickness of at least 2,000 Å. Specifically, the first layer may be formed of a material such as transparent molybdenum-titanium oxide (MoTiOx), molybdenum-tantalum oxide (MoOx:Ta), tungsten oxide (WOx), and molybdenum-copper oxide (MoCuOx). Additionally, the second layer may be composed of a single metal layer made of copper, or a double metal layer in which copper and molybdenum-titanium (MoTi) are stacked.

[0175] With this structure, reflective luminosity can be reduced to 5% or less. In this case, since the bank (BA) is a white organic material, it may not be possible to reduce reflective luminosity further. However, by forming the bank (BA) with a black organic material, reflective luminosity can be further reduced to achieve a level of 2%.

[0176] <Ninth Embodiment>

[0177] In the 7th and 8th embodiments, the cathode electrode and various wirings have a triple-layer stacked structure, thereby further providing the effect of suppressing external light reflection. In the 9th embodiment with reference to FIG. 15, a structure for suppressing external light reflection in an area excluding the cathode electrode and various wirings in a bottom-emitting electroluminescent display device is described. FIG. 15 is a cross-sectional view showing the structure of an electroluminescent display device according to the 9th embodiment of this application.

[0178] According to the 7th and 8th embodiments, external light reflection is suppressed in the cathode electrode (CAT) and various wirings, but there is still a possibility of external light reflection in parts excluding these areas. In particular, looking at the bank (BA) portion, a triple-layer structure cathode electrode (CAT) is arranged, but even if the external light reflection caused by the cathode electrode (CAT) is reduced to the 2% level, even the 2% level can affect the display quality to a degree that cannot be ignored.

[0179] In the ninth embodiment, an additional structure is proposed to suppress external light reflection as much as possible. For example, the bank (BA) can be formed from a black organic material. It is preferable that the black organic material includes an organic material with excellent light absorption properties. As a result, external light reflection is reduced to 2% in the part where the light-emitting diode (OLE) is formed, and the other part covered by the bank (BA) absorbs an additional 2% of external light reflection, thereby further reducing external light reflection to less than 1%.

[0180] In addition, in the case of a bottom-emitting type, a color filter may be placed below the flattening film (PL). In FIG. 14, the color filter (CF) is placed to completely overlap only the light-emitting region where the light-emitting diode (OLE) is formed. However, in the ninth embodiment, the color filter (CF) may be placed to extend to other regions.

[0181] For example, in a red pixel, a red color filter is placed in the light-emitting area. Additionally, in a red pixel, a red color filter may be placed continuously outside the light-emitting area. In a blue pixel, a blue color filter is placed in the light-emitting area, and a blue color filter may be placed continuously outside the light-emitting area. In a green pixel, a green color filter is placed in the light-emitting area, and a green color filter may be placed continuously outside the light-emitting area.

[0182] When color filters (CF) are extended across the entire pixel area, the bank (BA) may use a white bank or a black bank. If a black bank is used, external light reflection can be suppressed more.

[0183] Additionally, color filters (CF) can be arranged in various ways. For example, in the case described above, multiple pixels are arranged on the substrate (SUB), and at least three subpixels are assigned to each pixel. For example, a single pixel may include a red subpixel, a green subpixel, and a blue subpixel. A red color filter is placed on the red subpixel, a green color filter is placed on the green subpixel, and a red color filter is placed on the red subpixel.

[0184] A single subpixel may include a light-emitting region occupied by a light-emitting diode and a non-light-emitting region where wiring and thin-film transistors are placed. In the case of a top-emitting type, the light-emitting region may have a size approximately equal to that of the subpixel. However, in the case of a bottom-emitting type, the light-emitting region can be defined only as having a size equal to that of the light-emitting diode.

[0185] Accordingly, in the bottom-emitting type, color filters can be arranged to overlap with the light-emitting diode, which is the light-emitting region. However, in the ninth embodiment, the color filters are characterized by being arranged across the entire corresponding subpixel, that is, in addition to the light-emitting region, in the non-light-emitting region. For example, in a red subpixel, a red color filter can be arranged across the entire red subpixel area that includes both the light-emitting region and the non-light-emitting region. In a green subpixel, a green color filter can be arranged across the entire green subpixel area that includes both the light-emitting region and the non-light-emitting region. In a blue subpixel, a blue color filter can be arranged across the entire blue subpixel area that includes both the light-emitting region and the non-light-emitting region.

[0186] Alternatively, as illustrated in FIG. 16, a corresponding color filter may be placed in the light-emitting region, and red, green, and blue color filters may be placed together in the non-light-emitting region. FIG. 16 is a cross-sectional view showing the structure of an electroluminescent display device according to another example of the ninth embodiment of this application.

[0187] For example, a red color filter (CFR) may be placed in the light-emitting area of ​​a red subpixel, and red (CFR), green (CFG), and blue color filters (CFB) may be placed adjacently on the same plane in the non-light-emitting area. Similarly, a green color filter may be placed in the light-emitting area of ​​a green subpixel, and red, green, and blue color filters may be placed in the non-light-emitting area. Additionally, a blue color filter may be placed in the light-emitting area of ​​a blue subpixel, and red, green, and blue color filters may be placed in the non-light-emitting area.

[0188] Here, the red, green, and blue color filters placed in the non-emissive area can be arranged in equal area ratios. Alternatively, the area ratio of the blue color filter, which has a relatively low external light reflectivity, may be formed wider. As another example, if reflective visuality is considered in addition to reflectivity, the area ratio of the green or red color filters may be formed wider depending on the specific reflective visuality to be implemented.

[0189] To summarize the electroluminescent display device according to this application described above, this application can achieve a simple structure without a separate en-cap element by having a cathode electrode having a multilayer structure containing a conductive resin material. The embodiments described so far have focused on the most representative cases. In particular, the most important structure of this application is that the cathode electrode incorporates an en-cap function, so a complete electroluminescent display device can be realized without an additional en-cap layer. As a basic structure for this, as shown in FIG. 4, this application is characterized by the cathode electrode having at least a triple-layer structure.

[0190] The triple-layer structure provided by the cathode electrode according to this application comprises, in a first layer, a metal layer or a conductive metal oxide layer, in a second layer, a conductive resin layer, and in a third layer, a low-resistance metal layer for lowering the resistance of the cathode electrode. Herein, the configuration of the first and third layers can be varied, or additional electrode layers can be added to the basic triple-layer structure to create various configurations. Hereinafter, specific application examples that can be further implemented in this application are described with reference to the drawings.

[0191] FIG. 17 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to one application example of this application. Referring to FIG. 17, the electroluminescent display device according to one application example has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), and a third cathode electrode layer (CAT3) are sequentially stacked.

[0192] The first cathode electrode layer (CAT1) has a structure in which a metal layer (20) and a metal oxide layer (10) are continuously stacked. For example, the metal layer (20) may include a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The metal oxide layer (10) may be composed of a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO).

[0193] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the work function barrier energy.

[0194] The third cathode electrode layer (CAT3) may have a structure in which a lower metal oxide layer (11), a metal layer (20), and an upper metal oxide layer (30) are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are made of a metal oxide material, may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20), formed from a metal material, is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are formed from a metal oxide material.

[0195] FIG. 18 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application of this application. Referring to FIG. 18, the electroluminescent display device according to another application has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), a third cathode electrode layer (CAT3), and a fourth cathode electrode layer (CAT4) are sequentially stacked.

[0196] The first cathode electrode layer (CAT1) may have a structure in which a lower metal oxide layer (11), a metal layer (20), and an upper metal oxide layer (30) are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are made of a metal oxide material, may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20), formed from a metal material, is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are made of a metal oxide material. For example, the lower metal oxide layer (11) may be made of a metal oxide material selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). The metal layer (20) may be made of a metal material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The upper metal oxide layer (30) may be made of the same material as the lower metal oxide layer (11).

[0197] The second cathode electrode layer (CAT2) may include a conductive resin material. The conductive resin material may include a domain material composed of a resin material with high electron mobility and a dopant that lowers the work function barrier energy.

[0198] The third cathode electrode layer (CAT3) may have a structure in which a lower metal oxide layer (11), a metal layer (20), and an upper metal oxide layer (30) are sequentially stacked. Each of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are made of a metal oxide material, may have a thickness of 10 Å to 200 Å. The metal layer (20) may have a thickness of 100 Å to 3,000 Å. In particular, it is preferable that the metal layer (20), formed from a metal material, is thicker than the thickness of the lower metal oxide layer (11) and the upper metal oxide layer (30), which are formed from a metal oxide material.

[0199] The fourth cathode electrode layer (CAT4) may include a conductive resin material. The fourth cathode electrode layer (CAT4) may be formed of the same material as the second cathode electrode layer (CAT2).

[0200] FIG. 19 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application example of this application. Referring to FIG. 19, the electroluminescent display device according to another application example has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), a third cathode electrode layer (CAT3), a fourth cathode electrode layer (CAT4), and a fifth cathode electrode layer (CAT5) are sequentially stacked.

[0201] The structure of the cathode electrode (CAT) according to FIG. 19 has a structure in which a fifth cathode electrode layer (CAT5) is further added to the cathode electrode (CAT) according to FIG. 18. The fifth cathode electrode layer (CAT5) is a conductive layer made of a metallic material and may be made of a metallic material selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba). The metal layer (20) may have a thickness of 100 Å to 3,000 Å.

[0202] FIG. 20 is a cross-sectional view showing the stacked structure of a light-emitting diode in an electroluminescent display device according to another application example of this application. Referring to FIG. 19, the electroluminescent display device according to another application example has a structure in which an anode electrode (ANO), a light-emitting layer (EL), and a cathode electrode (CAT) are sequentially stacked. In particular, the cathode electrode (CAT) has a structure in which a first cathode electrode layer (CAT1), a second cathode electrode layer (CAT2), a third cathode electrode layer (CAT3), a fourth cathode electrode layer (CAT4), and a fifth cathode electrode layer (CAT5) are sequentially stacked.

[0203] In addition, this application can have the effect of suppressing external light reflection caused by destructive interference by configuring the first cathode electrode layer to be semi-transparent in a cathode electrode having at least three layers stacked. Furthermore, by having a triple-layer structure including a transparent conductive material in various wirings, the effect of suppressing external light reflection in the wiring portion can be further enhanced. In addition, by applying a black bank and / or color filter extension structure, the effect of further suppressing external light reflection can be achieved.

[0204] The features, structures, effects, etc. described in the examples of this application described above are included in at least one example of this application and are not necessarily limited to only one example. Furthermore, the features, structures, effects, etc. exemplified in at least one example of this application may be combined or modified and implemented in other examples by a person skilled in the art to which this application pertains. Therefore, matters related to such combinations and modifications should be interpreted as being included within the scope of this application.

[0205] It will be obvious to those skilled in the art to which this application pertains that the above-described application is not limited to the aforementioned embodiments and attached drawings, and that various substitutions, modifications, and alterations are possible within the scope of the technical details of this application. Therefore, the scope of this application is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of this application. Explanation of the symbols

[0206] OLE: Light Emitting Diode ANO: Anode Electrode EL: Emitting layer CAT: Cathode electrode CAT1: First cathode electrode layer CAT2: Second cathode electrode layer CAT4: Third cathode electrode layer 10: Metal oxide layer 11: Lower metal oxide layer 30: Upper metal oxide layer 20: Metal layer

Claims

Claim 1 An electroluminescent display device comprising: a substrate; an anode electrode disposed on the substrate; a light-emitting layer disposed on the anode electrode; and a cathode electrode disposed on the light-emitting layer, wherein the cathode electrode comprises: a first conductive layer in contact with the light-emitting layer; a second conductive layer in contact with the first conductive layer; and a third conductive layer in contact with the second conductive layer, wherein each of the first conductive layer and the third conductive layer comprises either a metal layer or a metal oxide layer, and the second conductive layer is made of a conductive resin material having a thickness of 2 μm to 4 μm. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 delete Claim 9 delete Claim 10 delete Claim 11 delete Claim 12 An electroluminescent display device according to claim 1, wherein the metal layer comprises any one selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), and the oxide metal layer comprises any one selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO). Claim 13 delete Claim 14 In claim 1, an electroluminescent display device in which the thickness of the metal layer is thicker than the thickness of the metal oxide layer. Claim 15 An electroluminescent display device according to claim 14, wherein the thickness of the oxide metal layer is 10 Å to 200 Å and the thickness of the metal layer is 100 Å to 3,000 Å. Claim 16 In claim 14, the metal layer comprises any one selected from aluminum (Al), silver (Ag), molybdenum (Mo), gold (Au), magnesium (Mg), calcium (Ca), and barium (Ba), and the oxide metal layer comprises any one selected from aluminum oxide (Al2O3), molybdenum oxide (MoO), magnesium oxide (MgO), calcium oxide (CaO), and barium oxide (BaO), an electroluminescent display device. Claim 17 delete Claim 18 The electroluminescent display device according to claim 1, wherein the conductive resin material comprises a domain material comprising any one of Alq3, TmPyPB, Bphen, TAZ, and TPB; and a dopant comprising any one selected from an alkali metal material comprising Li, Cs, Cs2O3, CsN3, and Rb2 and C60, dispersed within the domain material. Claim 19 An electroluminescent display device according to claim 1, wherein the first cathode electrode completely covers the end of the light-emitting layer, and the third cathode electrode is formed to completely cover the first cathode electrode. Claim 20 The electroluminescent display device according to claim 1, wherein the substrate comprises: a display area; a non-display area surrounding the display area; and further comprises a planarization film extending into a part of the non-display area and covering the entire display area below the anode electrode on the substrate, wherein the light-emitting layer is applied over the anode electrode with an area smaller than that of the planarization film, the first cathode electrode completely covers the entire light-emitting layer and the planarization film, and the third cathode electrode is formed to completely cover the first cathode electrode.

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