Patent Publication Number: US-2022238843-A1

Title: Organic light emitting diode display device and method of manufacturing the same

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of U.S. patent application Ser. No. 16/744,088, filed Jan. 15, 2020, which is a divisional of U.S. patent application Ser. No. 14/855,337, filed Sep. 15, 2015, now U.S. Pat. No. 10,547,028, which claims priority to and the benefit of Korean Patent Application No. 10-2015-0032501, filed Mar. 9, 2015, the entire content of all of which is incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Field 
     Aspects of embodiments of the present invention relate to an organic light emitting diode (OLED) display device and a method of manufacturing the same, and more particularly, to an OLED display device enhanced in regard to the adhesiveness between a substrate and an encapsulation structure, and a method of manufacturing the same. 
     2. Description of the Related Art 
     In organic light emitting diode (OLED) display devices, OLED elements are often deteriorated by the infiltration of oxygen or moisture thereinto. Accordingly, to reduce or effectively prevent the infiltration of oxygen or moisture, an encapsulation structure for encapsulating and protecting an OLED element from an external environment is needed. 
     Conventionally, as such an encapsulation structure, a thin film encapsulation structure having a multilayer structure, in which an organic layer and an inorganic layer are alternately stacked to cover an OLED element, has been widely used. In other words, an organic layer and an inorganic layer are alternately stacked on an OLED element of a substrate so as to encapsulate the OLED element. 
     The organic layer serves to provide the flexibility of a flat panel display (FPD) device while the inorganic layer serves to reduce or effectively prevent the infiltration of oxygen or moisture thereinto. Accordingly, to reduce or effectively prevent the external infiltration of oxygen or moisture, an organic layer is positioned at an inner portion of the display device to be adjacent an OLED element, and an inorganic layer is positioned at an outer portion of the display device. 
     Meanwhile, prior to forming such an encapsulation structure, there may be a case in which a few residual organic layers are unnecessarily or inadvertently deposited while forming an OLED element, for example, at an outer portion of the OLED element. Because the deposited portion of the OLED element is an area only requiring an inorganic layer, when an organic layer is present in such an area, the adhesiveness between a substrate and an encapsulation structure may decrease, such that a peeling-off issue is caused, and such that the external infiltration of moisture or oxygen occurs, thereby resulting in a dark spot defect. 
     It is to be understood that this background of the technology section is intended to provide useful background for understanding the technology and as such, the technology background section may include ideas, concepts, or observations that were not part of what was known or appreciated by those skilled in the pertinent art prior to a corresponding effective filing date of subject matter disclosed herein. 
     SUMMARY 
     One or more embodiments of the present invention are directed to an organic light emitting diode (OLED) display device capable of removing a residual organic layer, which remains on a substrate by performing a cleaning process prior to forming an encapsulation structure. 
     In addition, the adhesiveness between a substrate and an encapsulation structure may be enhanced, and the external infiltration of moisture or oxygen thereinto may be reduced or effectively prevented, by removing such a residual organic layer through use of the organic light emitting diode display device and a method of manufacturing the same. 
     According to an embodiment of the present invention, a method of manufacturing an organic light emitting diode display device includes providing a substrate including a display area and a non-display area; forming an organic light emitting diode element in the display area; forming a barrier wall around the display area and spaced apart from the organic light emitting diode element; performing a plasma treatment on the substrate on which the organic light emitting diode element is formed; and forming a thin film encapsulation layer for coating the organic light emitting diode element, wherein the forming of the thin film encapsulation layer includes: forming at least one inorganic layer; and forming at least one organic layer inwardly of the barrier wall 
     The forming of the organic light emitting diode element may include: forming an insulating layer on the substrate; forming a pattern of a first electrode on the insulating layer; forming a pixel defining layer by which the patterned first electrode is divided into a pixel unit; forming a light emitting layer on the first electrode; and forming a second electrode on the light emitting layer, wherein the barrier wall and the pixel defining layer are formed in the same process. 
     The plasma treatment may be performed under in an inert gas atmosphere. 
     The at least one inorganic layer and the at least one organic layer may include a total of 2 to 20 layers. 
     The barrier wall may have a height less than or equal to a height of an uppermost inorganic layer of the thin film encapsulation layer. 
     Forming the barrier wall may include forming two or more barrier walls. 
     A height difference may be present between the two or more barrier walls. 
     The barrier wall may be at least one of an organic material and an inorganic material. 
     The barrier wall comprises the organic material which may include at least one of a photoresist, a polyacrylic resin, a polyimide resin, and an acrylic resin. 
     The barrier wall comprises the inorganic material which may include a silicon compound. 
     According to another embodiment of the present invention, an organic light emitting diode display device includes: a substrate including a display area and a non-display area; an organic light emitting diode element located at the display area; a thin film encapsulation layer coating the organic light emitting diode element; and a barrier wall around the display area and spaced apart from the organic light emitting diode element, wherein the thin film encapsulation layer is a multilayer in which at least one inorganic layer and at least one organic layer are alternately stacked, and wherein the at least one organic layer of the thin film encapsulation layer is located inward of the barrier wall. 
     The organic light emitting diode element may include a first electrode, a light emitting layer, and a second electrode which are sequentially stacked. 
     An outer side of the barrier wall may directly contact the inorganic layer. 
     The at least one inorganic layer and the at least one organic layer may include 2 to 20 alternately stacked layers. 
     The barrier wall may have a height that is the same as a height of an uppermost inorganic layer of the thin film encapsulation layer. 
     The barrier wall may include two or more barrier walls. 
     A height difference may be present between the two or more barrier walls. 
     The barrier wall may include at least one of an organic material and an inorganic material. 
     The organic material may include at least one of a photoresist, a polyacrylic resin, a polyimide resin, and an acrylic resin. 
     The inorganic material may include a silicon compound. 
     The foregoing is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other features and aspects of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a plan view schematically illustrating an organic light emitting diode (OLED) display device according to an exemplary embodiment; 
         FIG. 2  is a cross-sectional view taken along the line I-I′ of  FIG. 1 ; 
         FIG. 3  is a plan view schematically illustrating an OLED display device according to another exemplary embodiment; 
         FIG. 4  is a cross-sectional view schematically illustrating an OLED display device according to the embodiment of  FIG. 3 ; 
         FIG. 5  is a plan view illustrating a pixel in area A of  FIG. 1 ; 
         FIG. 6  is a cross-sectional view taken along the line A-A′ of  FIG. 5 ; 
         FIGS. 7A through 7E  are cross-sectional views illustrating sequential processes of a method of manufacturing an OLED display device according to an exemplary embodiment, respectively; and 
         FIGS. 8 and 9  are images illustrating a surface analysis on an adhesive area between a substrate and a thin film encapsulation layer of OLED display devices according to a first Inventive Example and according to a first Comparative Example, respectively. 
     
    
    
     DETAILED DESCRIPTION 
     Hereinafter, exemplary embodiments of the present invention will now be described in more detail with reference to the accompanying drawings. 
     The invention, however, may be embodied in many different forms, and should not be construed as being limited to the exemplary embodiments set forth herein. Rather, these exemplary embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of present the invention to those skilled in the art. 
     Also, terms used herein refer to general terms that are currently in wide use. However, if certain terms are randomly selected by the applicant, such terms should be described in the detailed description, or should be identified based on the intent of the usage thereof. 
     When it is determined that a detailed description of a technique known in the art may make the purpose of the present invention unnecessarily ambiguous in the present description, the particular detailed description will be omitted. In addition, the same components and corresponding components are given the same reference numeral. Further, the areas illustrated in the drawings are schematic in nature, and their shapes are neither intended to illustrate the actual shape of an area of a device nor intended to limit the scope of exemplary embodiments. 
     In the drawings, thicknesses of a plurality of layers and areas may be illustrated in an enlarged manner for clarity and for ease of description thereof. When a layer, area, or plate is referred to as being “on” another layer, area, or plate, it may be directly on the other layer, area, or plate, or one or more intervening layers, areas, or plates may be present therebetween. 
     Expressions such as “at least one of,” when preceding a list of elements, modify the entire list of elements and do not modify the individual elements of the list. Further, the use of “may” when describing embodiments of the present invention refers to “one or more embodiments of the present invention.” It will be understood that when an element or layer is referred to as being “on,” “connected to,” “coupled to,” or “adjacent” another element or layer, it can be directly on, connected to, coupled to, or adjacent the other element or layer, or one or more intervening elements or layers may be present. When an element or layer is referred to as being “directly on,” “directly connected to,” “directly coupled to,” or “immediately adjacent” another element or layer, there are no intervening elements or layers present. 
     Spatially relative terms, such as “beneath,” “below,” “lower,” “downward,” “above,” “upper,” and the like, may be used herein for ease of description to describe one element&#39;s or feature&#39;s relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or in operation in addition to the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as “below” or “beneath” other elements or features would then be oriented “above” the other elements or features. Thus, the exemplary term “below” can encompass both an orientation of above and below. The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein should be interpreted accordingly. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it may be the only layer between the two layers, or one or more intervening layers may also be present. 
     It will be understood that, although the terms “first,” “second,” “third,” etc., may be used herein to describe various elements, components, regions, layers, and/or sections, these elements, components, regions, layers and/or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or section from another element, component, region, layer, or section. Thus, a first element, component, region, layer, or section discussed below could be termed a second element, component, region, layer, or section, without departing from the spirit and scope of the present inventive concept. 
     The terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting of the inventive concept. As used herein, the singular forms “a” and “an” are intended to include the plural forms as well, unless the context clearly indicates otherwise. As used herein, the term “and/or” includes any and all combinations of one or more of the associated listed items. Also, the term “exemplary” is intended to refer to an example or illustration. 
       FIG. 1  is a plan view schematically illustrating an OLED display device according to an exemplary embodiment. 
     Referring to  FIG. 1 , a substrate  100  of the OLED display device may include a display area DA and a non-display area NDA formed around the display area DA. The display area DA may be defined as an area at which an OLED element is located. The configuration of the OLED display device illustrated in  FIG. 1  will further be described with reference to  FIG. 2 . 
     The non-display area NDA may include a first non-display area NDA 1  formed around the display area DA, a barrier wall  400 , and a second non-display area NDA 2  formed outwardly of the barrier wall  400 . In detail, the first non-display area NDA 1  may be defined as an area between the display area DA and the barrier wall  400 , and the second non-display area NDA 2  may be defined as an area surrounding the barrier wall  400 . 
       FIG. 2  is a cross-sectional view taken along the line I-I′ of  FIG. 1 . 
     Referring to  FIG. 2 , the OLED display device may include the substrate  100  including the display area DA and the non-display area NDA; the OLED element  200  located in the display area DA; a thin film encapsulation layer  300  coating the OLED element  200 ; and the barrier wall  400  located around the display area DA to be spaced apart from the OLED element  200 . The thin film encapsulation layer  300  may have a multilayer structure in which one or more inorganic layers  310  and  330  and at least one organic layer  320  are alternately stacked. The organic layer  320  of the thin film encapsulation layer  300  may be located inwardly of the barrier wall  400 . 
     The substrate  100  may be any substrate that may be used in a conventional OLED display device, and may be a glass substrate or a transparent plastic substrate having excellent mechanical strength, thermal stability, transparency, surface smoothness, ease of handling, and water resistance. A planarization layer, an insulating layer, and the like, may further be provided on the substrate  100 , and as such, various suitable modifications may be made to the substrate  100 . 
     The OLED element  200  located in the display area DA of the substrate  100  may include a first electrode, a light emitting layer, and a second electrode that are sequentially stacked. A detailed description of the OLED element  200  will further be provided with reference to  FIGS. 3 and 4 . 
     The thin film encapsulation layer  300  coating the OLED element  200  may be provided, and may include the first inorganic layer  310 , the first organic layer  320 , and the second inorganic layer  330 . 
     The thin film encapsulation layer  300  may have a multilayer structure in which one or more inorganic layers and one or more organic layers are alternately stacked for a total of 2 to 20 layers. However, the number of the organic and inorganic layers is not limited thereto. 
     Referring to  FIG. 2 , the barrier wall  400  may be located on the substrate  100  around the display area DA, which is defined by the OLED element  200 , to be spaced apart from the OLED element  200 . 
     The barrier wall  400  may be located in the non-display area NDA to be spaced apart from the OLED element  200 . The organic layer  320  of the thin film encapsulation layer  300  may be located inwardly of the barrier wall  400 , thus allowing a monomer for forming an organic layer to be only deposited in a desired position. 
     The barrier wall  400  may be formed simultaneously with a formation of a pixel defining layer. Accordingly, manufacturing an additional mask may be unnecessary, and a material for forming the barrier wall  400  may use any conventional material suitable for forming a pixel defining layer. In detail, such a material for forming the barrier wall  400  may include one or more of the following materials: an organic material such as a photoresist, a polyacrylic resin, a polyimide resin, and an acrylic resin, and an inorganic material, such as a silicon compound. 
     According to the exemplary embodiment, the barrier wall  400  may be formed without being particularly limited by the position, the shape, the size, or the number thereof. 
     The barrier wall  400  may be present in any position within the non-display area NDA. However, more particularly, the barrier wall  400  may be positioned in the vicinity of the display area DA to improve the non-display area NDA. In addition, the barrier wall  400  may have a straight-line shape or a dotted-line shape, and may also be formed to have various desired shapes, such as a quadrangular shape, a circular shape, or a triangular shape. 
     With regard to the size of the barrier wall  400 , because a height of the barrier wall  400  is affected by a thickness of the thin film encapsulation layer  300 , the height of the barrier wall  400  may be, more particularly, less than the thickness of the thin film encapsulation layer  300 , and because a width of the barrier wall  400  is affected by a width of the non-display area NDA, the width of the barrier wall  400  may be, more particularly, less than the width of the non-display area NDA. 
     As an example, the height of the barrier wall  400  may be the same as, substantially the same as, lower than, or higher than a height of an uppermost organic layer constituting the thin film encapsulation layer  300  (e.g., organic layer  320 ). As another example, the height of the barrier wall  400  may be, more particularly, the same as, substantially the same as, or lower than a height of an uppermost inorganic layer constituting the thin film encapsulation layer  300  (e.g, inorganic layer  330 ). 
     Because the barrier wall  400  is obtained by performing a patterning on a mask for a pixel defining layer in a desired manner, the barrier wall  400  may be formed to have two sides or four sides thereof, or may be formed at a desired position. 
       FIG. 2  illustrates an example in which a single barrier wall  400  is located in the non-display area NDA, and as illustrated in  FIG. 1 , the barrier wall  400  is formed to have four sides provided in a single-wall structure. 
       FIGS. 3 and 4  are views schematically illustrating a structure of an OLED display device including two layers of the barrier wall  400  according to another exemplary embodiment. 
     Referring to  FIG. 3 , and unlike the embodiment described with respect to  FIGS. 1 and 2 , the barrier wall  400  may have a double-wall structure in which continuous upper, left, and right sides, that is, three continuous sides of the barrier wall  400 , are formed absent a continuous lower side thereof. Although  FIG. 3  illustrates the barrier wall  400  as a single-wall structure, it may be appreciated that the barrier wall  400  of  FIG. 3  may include a first barrier wall  410  and a second barrier wall  420 , which are illustrated in  FIG. 4 . 
     As illustrated in  FIG. 4 , the barrier wall  400  may have a double-wall structure including the first barrier wall  410  and the second barrier wall  420 . Although the present exemplary embodiment illustrates the double-wall structure including two layers  410  and  420  of the barrier wall  400 , the number of layers of the barrier wall  400  is not particularly limited, and the number of layers of the barrier wall  400  may be provided in various manners, given that the barrier wall  400  does not exceed the width of the non-display area NDA. 
     Although  FIG. 4  illustrates an example in which a height of the first barrier wall  410  is the same or substantially the same as a height of the second barrier wall  420 , when two or more layers of the barrier wall  400  are used, a height difference may be present between two or more of the various layers. 
     The first barrier wall  410  and the second barrier wall  420  may be formed simultaneously with the formation of the OLED element  200 , more particularly, with the formation of the pixel defining layer. Subsequently, the first inorganic layer  310  of the thin film encapsulation layer  300  may coat the OLED element  200 , and in this instance, the first inorganic layer  310  may be deposited over the substrate  100 , absent portions of the substrate  100  on which the first barrier wall  410  and the second barrier wall  420 , provided in the double-wall structure, are formed. The first organic layer  320  may be formed inwardly of the first barrier wall  410  (e.g., one of the two layers of the barrier wall  400  having the double-wall structure), and the second inorganic layer  330 , which coats the first organic layer  320  and the barrier wall  400  (e.g., the first barrier wall  410  and the second barrier wall  420 ), may be formed. 
     Referring to  FIGS. 3 and 4 , although the OLED display device according to the other exemplary embodiment illustrates the barrier wall  400 , that is, the first barrier wall  410  and the second barrier wall  420  provided in the double-wall structure, as being located in a straight-line shape, the barrier wall  400  having the double-wall structure may have a dotted-line shape, as previously described, and may be formed to have various shapes, such as a circular shape, a triangular shape, or the like. 
     According to still another exemplary embodiment, an OLED display device including a thin film encapsulation layer having a plurality of inorganic and organic layers may be provided. A height of a barrier wall may be adjusted based on the number of the inorganic and organic layers. 
     The thin film encapsulation layer of the OLED display device according to such an exemplary embodiment may include a first inorganic layer, a first organic layer, a second inorganic layer, a second organic layer, and a third inorganic layer. Although the thin film encapsulation layer including the three inorganic layers and the two organic layers is exemplified herein, the OLED display device according to the present exemplary embodiment may have a thin film encapsulation layer in which an even greater number of inorganic layers and organic layers are alternately stacked. 
     According to the present exemplary embodiment, a first organic material for forming the first organic layer and a second organic material for forming the second organic layer may be the same as each other, or may differ from one another. Although the first organic material for forming the first organic layer is exemplified herein for ease of description, another organic layer constituting the thin film encapsulation layer may also be formed of materials described herein below. 
     The first organic material for forming the first organic layer may be one or more of the following materials: an acrylic resin, a methacrylic resin, polyisoprene, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a perylene resin, and/or other polymer materials. 
     In detail, examples of the acrylic resin may include butylacrylate, ethylhexylacrylate, and the like; examples of the methacrylic resin may include propyleneglycolmethacrylate, tetrahydrofurfuryl methacrylate, and the like; examples of the vinyl resin may include vinylacetate, N-vinylpyrrolidone (NVP), and the like; examples of the epoxy resin may include cycloaliphatic epoxide, epoxy acrylate, a vinyl epoxy resin, and the like; examples of the urethane resin may include urethane acrylate, and the like; examples of the cellulose resin may include cellulosenitrate, and the like. However, the examples thereof are not limited thereto. 
     Similarly, a first inorganic material for forming the first inorganic layer, a second inorganic material for forming the second inorganic layer, and a third inorganic material for forming the third inorganic layer may be the same as, or may differ from, one another. Although the first inorganic material for forming the first inorganic layer is exemplified herein for ease of description, another inorganic layer constituting the thin film encapsulation layer may also be formed of materials described herein below. 
     The first inorganic material for forming the first inorganic layer may be one or more of the following materials: silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and/or silicon oxynitride (SiO x N y ). 
     Hereinafter, a pixel of the OLED element  200  will be described with reference to  FIGS. 5 and 6 . 
       FIG. 5  is a plan view illustrating a pixel in area A of  FIG. 1 . 
     Referring to  FIG. 5 , in the OLED display device according to the exemplary embodiment, a plurality of pixel areas may be defined by a boundary among a gate line(s)  101 , a data line  102  insulated from and crossing the gate line  101 , and a common power line  103 , and a single pixel may be located in a single pixel area therebetween. However, the definition of the pixel area is not limited thereto, and the pixel area may be defined by a pixel defining layer to be described further below. Alternatively, a plurality of pixels may be located in a single pixel area. 
     A single pixel of the OLED display device according to the exemplary embodiment may have a 2TFT-1CAP structure including two thin film transistors (e.g., a switching thin film transistor (TFT)  104  and a driving TFT  105 ), and a single capacitor (e.g., a capacitor (CAP)  106 ). However, the structure of the pixel is not limited thereto, and a single pixel may include three or more thin film transistors and two or more capacitors. 
     The switching TFT  104  may select a pixel to perform light emission. The switching TFT  104  may include a switching gate electrode  104   a  connected to the gate line  101 , a switching source electrode  104   b  connected to the data line  102 , a switching drain electrode  104   c  connected to a first capacitor plate  106   a , and a switching semiconductor layer  104   d.    
     The driving TFT  105  may apply driving power for allowing a light emitting layer  230  (as shown in  FIG. 6 ) in the pixel selected by the switching TFT  104  to perform light emission. The driving TFT  105  may include a driving gate electrode  105   a  connected to the first capacitor plate  106   a , a driving source electrode  105   b  connected to the common power line  103 , a driving drain electrode  105   c  connected to a first electrode  210  of the OLED element  200 , and a driving semiconductor layer  105   d.    
     The CAP  106  may include the first capacitor plate  106   a  and a second capacitor plate  106   b . The first capacitor plate  106   a  may be connected to the switching drain electrode  104   c  and the driving gate electrode  105   a , and the second capacitor plate  106   b  may be connected to the common power line  103 . Capacitance of the CAP  106  may be determined by electric charge stored in the CAP  106  and by voltage between the first capacitor plate  106   a  and the second capacitor plate  106   b.    
     A voltage having a level that is equivalent to a difference between a level of a data voltage transmitted by (or from) the switching TFT  104  and a level of a common voltage applied from the common power line  103  to the driving TFT  105  may be stored in the CAP  106 , and a current having a level corresponding to the level of the voltage stored in the CAP  106  may flow to the light emitting layer  230  through the driving TFT  105  to allow the light emitting layer  230  to perform light emission. 
       FIG. 6  is a cross-sectional view taken along the line A-A′ of  FIG. 5 . 
     Referring to  FIG. 6 , the OLED display device according to the exemplary embodiment may include the substrate  100 , a driving circuit  130 , the OLED element  200 , and the thin film encapsulation layer  300 . 
     As previously described with reference to  FIG. 2 , the substrate  100  may use an insulating substrate formed of one of the following materials: glass, quartz, ceramic, and plastic. However, the type of material forming the substrate  100  is not limited thereto, and the substrate  100  may also use a metallic substrate formed of stainless steel, or the like. 
     A buffer layer  107  may be located on the substrate  100 , the buffer layer  107  including an inorganic layer or an organic layer. The buffer layer  107  may reduce or effectively prevent the infiltration of undesired components, such as impure elements or moisture through the substrate  100  and may also planarize a surface of the substrate  100 . In addition, a gate insulating layer  108  may be located on the substrate  100  between the switching gate electrode  104   a  and the switching semiconductor layer  104   d , and also between the driving gate electrode  105   a  and the driving semiconductor layer  105   d . An insulating interlayer  109  may be located on the substrate  100  between the first capacitor plate  106   a  and the second capacitor plate  106   b.    
     The driving circuit  130  may be located on the buffer layer  107 . The driving circuit  130 , including the switching TFT  104 , the driving TFT  105 , and the CAP  106 , may drive the OLED element  200 . As previously described with reference to  FIG. 3 , the OLED element  200  may display an image by emitting light based on a driving signal transmitted from the driving circuit  130 . 
     The OLED element  200  may include the first electrode  210 , the light emitting layer  230  located on the first electrode  210 , and a second electrode  250  located on the light emitting layer  230 . The first electrode  210  may be an anode that injects holes, and the second electrode  250  may be a cathode that injects electrons. However, the types of the first and second electrodes  210  and  250  are not limited thereto, and may be modified such that the first electrode  210  is a cathode and the second electrode  250  is an anode. 
     As another example, at least one of a hole injection layer and a hole transporting layer may further be interposed between the first electrode  210  and the light emitting layer  230 , and at least one of an electron transporting layer and an electron injection layer may further be interposed between the light emitting layer  230  and the second electrode  250 . 
     The OLED display device according to the exemplary embodiment may be a top-emission-type display device. Accordingly, the first electrode  210  may include a reflective layer, and the second electrode  250  may include a transflective layer. However, the type of the OLED display device is not limited thereto, and the OLED display device may instead be a bottom-emission-type display device. In this case, the first electrode  210  may include a transflective layer, and the second electrode  250  may include a reflective layer. 
     The reflective layer and the transflective layer may include one or more of the following metals: magnesium (Mg), silver (Ag), gold (Au), calcium (Ca), lithium (Li), chromium (Cr), aluminum (Al), and/or an alloy thereof. The type of the layer, that is, whether the reflective layer or the transflective layer, may be determined based on a thickness of the layer. In general, the transflective layer has a thickness of less than or equal to about 200 nanometers (nm). 
     The first electrode  210  may further include a transparent conductive layer, and the transparent conductive layer may include one or more transparent conductive oxides (TCO), such as indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), and/or indium oxide (In 2 O 3 ). 
     The first electrode  210  may have a structure including a reflective layer, a double-layer structure including a reflective layer and a transparent conductive layer, or a triple-layer structure in which a transparent conductive layer, a reflective layer, and a transparent conductive layer are sequentially stacked. However, the structure of the first electrode  210  is not limited thereto, and the first electrode  120  may have a structure including a transparent conductive layer. 
     A pixel defining layer (PDL)  190  may be interposed between the first electrodes  210  of different/adjacent pixels. The PDL  190  may be formed of an insulating material, and may divide the first electrode  210  according to a pixel unit. In detail, the PDL  190  may be located on an edge portion of the first electrode  210  to divide the first electrode  210  in a pixel unit, to thereby define a pixel area. 
     The light emitting layer  230  may be located between the first electrode  210  and the second electrode  250 . In other words, the light emitting layer  230  may be located in an aperture on the first electrode  210  that is defined by the PDL  190 . The light emitting layer  230  may include a red light emitting layer, a green light emitting layer, and/or a blue light emitting layer. 
     The light emitting layer  230  may be formed in various ways, such as, for example, through a deposition process or through a transfer process using a donor film for transfer. 
     At least one of a hole injection layer, a hole transporting layer, an electron transporting layer, and an electron injection layer may further be provided between the first electrode  210  and the second electrode  250 , in addition to the light emitting layer  230  therebetween. The light emitting layer  230 , the hole injection layer, the hole transporting layer, the electron transporting layer, and the electron injection layer may be collectively referred to as an organic layer. Such an organic layer may be formed of a low molecular weight organic material or a polymer organic material. 
     The low molecular weight organic material may be applied to all of the hole injection layer, the hole transporting layer, the light emitting layer  230 , the electron transporting layer, and/or the electron injection layer. The low molecular weight organic material may be stacked to have a single structure or a composite structure. The low molecular weight organic material may include copper phthalocyanine (CuPc), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), tris-8-hydroxyquinoline aluminum) (Alq3), and/or the like. By performing a vacuum deposition process using a mask, the light emitting layer  230 , the hole injection layer, the hole transporting layer, the electron transporting layer, the electron injection layer, and the like, may be formed using the low molecular weight organic material. 
     The polymer organic material may be applied to the hole transporting layer and the light emitting layer  230 . In this instance, the hole transporting layer may use poly 3,4-ethylenedioxythiophene (PEDOT), and the light emitting layer  230  may use a poly-phenylenevinylene (PPV)-based polymer organic material and a polyfluorene-based polymer organic material. 
     The second electrode  250  may be located on the light emitting layer  230  and the PDL  190 . The second electrode  250  may be formed of a material commonly used in the pertinent art. The second electrode  250  may use a transparent electrode or a reflective electrode. In an embodiment that uses a transparent electrode, the second electrode  250  may include a layer formed of Li, Ca, LiF/Ca, LiF/Al, Al, or Mg, or a compound thereof, and another layer formed thereon using a material for forming a transparent electrode such as, for example, ITO, IZO, ZnO, or In 2 O 3 . In a case of using a reflective electrode, the second electrode  250  may include a layer formed of Li, Ca, LiF/Ca, LiF/AI, Al, or Mg or a compound thereof. As the example illustrated in  FIG. 4  depicts a top-emission-type OLED display device, the second electrode  250  may be manufactured as a transparent electrode. For example, the second electrode  250  may be formed of LiF/Al. 
     A capping layer may be formed on the second electrode  250 . The capping layer may be formed of a transparent material having an ultraviolet (UV) light barrier characteristic, and may protect the OLED element  200  that includes the first electrode  210 , the light emitting layer  230 , and the second electrode  250 . 
     As previously described with reference to  FIG. 2 , the thin film encapsulation layer  300 , which has the multilayer structure in which the first inorganic layer  310 , the first organic layer  320 , and the second inorganic layer  330  are stacked, may be formed on the OLED element  200 . In this instance, the first inorganic layer  310  and the second inorganic layer  330  may reduce or effectively prevent the infiltration of moisture or oxygen thereinto, and the first organic layer  320  may planarize a surface above the OLED element  200 . 
     A method of manufacturing the OLED display device according to the exemplary embodiment may include: providing a substrate  100  including a display area DA and a non-display area NDA; forming an OLED element  200  in the display area DA; forming a barrier wall  400  around the display area DA to be spaced apart from the OLED element  200 ; performing a plasma treatment on the substrate  100  on which the OLED element  200  is formed; and forming a thin film encapsulation layer  300  coating the OLED element  200 . The forming of the thin film encapsulation layer  300  may include: forming an inorganic layer (e.g., inorganic layer  310 ); and forming an organic layer (e.g., organic layer  320 ). In the forming of the organic layer, the organic layer may be formed inwardly of the barrier wall (e.g., such that the organic layer is surrounded by the barrier wall  400 ). 
     Hereinafter, the method of manufacturing the OLED display device according to the exemplary embodiment will be described in detail with reference to  FIGS. 7A through 7E . 
     The OLED element  200  may be formed in the display area DA of the substrate  100 . 
     The forming of the OLED element  200  may include: forming an insulating layer on the substrate  100 ; forming a pattern of a first electrode on the insulating layer; forming a pixel defining layer by which the patterned first electrode is divided into a pixel unit; forming a light emitting layer on the first electrode in the pixel unit; and forming a second electrode on the light emitting layer. 
     The first electrode, the light emitting layer, and the second electrode of the OLED element  200  may be formed through a deposition process, a sputtering process, and/or a coating process, which are known or suitable to those skilled in the art. In this instance, at least one of a hole injection layer, a hole transporting layer, an electron transporting layer, and an electron injection layer may further be formed between the first electrode and the second electrode, in addition to the light emitting layer therebetween. 
     According to the present exemplary embodiment, the forming of the barrier wall  400  may be performed simultaneously with the forming of the pixel defining layer. 
     In this instance, the barrier wall  400  may be formed without manufacturing an additional mask, as a patterning for the barrier wall  400  may be added onto the non-display area NDA at the time of manufacturing the mask for forming the pixel defining layer. 
     The material for forming the barrier wall  400  may use the same material or substantially the same material as that of the material for forming the pixel defining layer. In detail, the material for forming the barrier wall  400  may include one of the following materials: an organic material such as a photoresist, a polyacrylic resin, a polyimide resin, and/or an acrylic resin, and an inorganic material such as a silicon compound. 
     The barrier wall  400  may be formed without being particularly limited by the position, the shape, the size, and the number thereof. The position of the barrier wall  400  may be present in any position within the non-display area NDA. However, more particularly, the barrier wall  400  may be positioned in the vicinity of the display area DA to improve the non-display area NDA. In addition, the barrier wall  400  may be formed to have various desired shapes such as a quadrangular shape, a circular shape, or a triangular shape. 
     With regard to the size of the barrier wall  400 , since a height of the barrier wall  400  is affected by a thickness of the thin film encapsulation layer  300 , the height of the barrier wall  400  may be, more particularly, less than the thickness of the thin film encapsulation layer  300 , and because a width of the barrier wall  400  is affected by a width of the non-display area NDA, the width of the barrier wall  400  may be, in some embodiments, less than the width of the non-display area NDA. 
     As an example, the height of the barrier wall  400  may be formed to be the same as, lower than, or higher than a height of an uppermost organic layer constituting the thin film encapsulation layer  300 . As another example, the height of the barrier wall  400  may be, more particularly, the same as, substantially the same as, or lower than, a height of an uppermost inorganic layer constituting the thin film encapsulation layer  300 . 
     Referring to  FIG. 7A , in the forming of the OLED element  200 , a residual organic layer  200 ′, which is a portion of an organic layer remaining on the substrate  100  (the organic layer including, for example the light emitting layer, a hole injection layer, a hole transporting layer, an electron transporting layer, and an electron injection layer) may be deposited in the non-display area NDA. 
     Since the non-display area NDA of the substrate  100 , for example, the second non-display area NDA 2  located outwardly of the barrier wall  400 , is an area in which only an inorganic layer of a thin film encapsulation layer is required, when an organic layer (e.g., the residual organic layer  200 ′) is present in such an area, the adhesiveness between the substrate  100  and the thin film encapsulation layer may decrease to thereby cause a peeling-off issue, thereby potentially allowing the external infiltration of moisture and oxygen, thus resulting in a dark spot defect. 
     As illustrated in  FIG. 7B , a plasma treatment may be performed to clean the substrate  100  on which the OLED element  200  is formed, such as by using a cleaning gas  60 , such that the residual organic layer  200 ′ generated during the forming of the OLED element  200  may be removed. 
     More particularly, the plasma cleaning treatment may be performed under an inert gas atmosphere. Examples of the inert gas may include argon (Ar), nitrogen (N 2 ), and the like. At the time of performing the plasma treatment, a degree of vacuum (e.g., the pressure in the inert gas atmosphere) may be in a range of about 0.5 Torr to about 2.5 Torr, more particularly, about 1.5 Torr; a flow rate of the inert gas may be in a range of about 5,000 standard cubic centimeters (sccm) to about 10,000 sccm; a level of radio-frequency (RF) power may be in a range of about 1,000 watts (W) to about 5,000 W; and a period of time for the plasma treatment may be within one minute, for example, in a range of about one second (s) to about 10 s. 
     In the aforementioned condition of the plasma treatment, an excellent cleaning effect thereof may be achieved. However, the condition of the plasma cleaning treatment is not limited thereto, and may be adjusted in various manners within the extent in which the residual organic layer  200 ′ is effectively removed. 
     Through the plasma cleaning treatment, the residual organic layer  200 ′ present in the non-display area NDA of the substrate  100 , more particularly, the residual organic layer  200 ′ present in the second non-display area NDA 2 , may be removed. 
     As illustrated in  FIGS. 7C through 7E , the thin film encapsulation layer  300  coating the OLED element  200  may be formed. 
     The forming of the thin film encapsulation layer  300  may include forming an inorganic layer and forming an organic layer. The forming of the inorganic layer and the forming of the organic layer may be alternately performed a total of 2 to 20 times so as to form the thin film encapsulation layer  300  having the multilayer structure. 
     Referring to  FIG. 7C , the first inorganic layer  310  coating the OLED element  200  may be formed on the substrate  100  on which the OLED element  200  is formed. The first inorganic layer  310  may be formed by performing a deposition process over the substrate  100 , with the exception of over a portion(s) of the substrate  100  on which the barrier wall  400  is formed. 
     A material for forming the first inorganic layer  310  may be one or more of the following materials: silicon nitride, aluminum nitride, zirconium nitride, titanium nitride, hafnium nitride, tantalum nitride, silicon oxide, aluminum oxide, titanium oxide, tin oxide, cerium oxide, and/or silicon oxynitride (SiO x N y ). 
     As illustrated in  FIGS. 7D and 7E , the first organic layer  320  and the second inorganic layer  330  may be sequentially formed on the first inorganic layer  310 . 
     A material for forming the first organic layer  320  may be one or more of the following materials: an acrylic resin, a methacrylic resin, polyisoprene, a vinyl resin, an epoxy resin, a urethane resin, a cellulose resin, a perylene resin, and/or other polymer materials. 
     In detail, examples of the acrylic resin may include butylacrylate, ethylhexylacrylate, and the like; examples of the methacrylic resin may include propyleneglycolmethacrylate, tetrahydrofurfuryl methacrylate, and the like; examples of the vinyl resin may include vinylacetate, N-vinylpyrrolidone (NVP), and the like; examples of the epoxy resin may include cycloaliphatic epoxide, epoxy acrylate, a vinyl epoxy resin, and the like; examples of the urethane resin may include urethane acrylate, and the like; and examples of the cellulose resin may include cellulosenitrate, and the like. However, the examples thereof are not limited thereto. 
     The first organic layer  320  may be formed by depositing monomers, and may be formed inwardly of (e.g., surrounded by) the barrier wall  400 . Through the organic layer  320  being deposited only on a position requiring the deposition due to the barrier wall  400 , issues of decreased adhesiveness, a dark spot defect, and the like, which may be otherwise caused by the monomers flowing into an area in which an inorganic layer is formed, may be addressed. 
     In addition, prior to forming the second inorganic layer  330  on the first organic layer  320 , the plasma cleaning treatment described with reference to  FIG. 7B  may be performed. Through the plasma cleaning treatment, monomers deposited in an area that does not require deposition at the time of the forming of the first organic layer  320  may be effectively removed. 
     For any description omitted herein pertaining to a material for forming the second inorganic layer  330  and a process of forming thereof, reference may be made to analogous features of the first inorganic layer  310  described with reference to  FIG. 7C . 
     Although  FIGS. 7D and 7E  illustrate an example in which the first organic layer  320  and the second inorganic layer  330  are additionally formed on the first inorganic layer  310 , the forming of the inorganic layer and the forming of the organic layer may be alternately performed a total of 2 to 20 times to thereby form a thin film encapsulation layer in which a plurality of organic and inorganic layers are stacked. 
     As described hereinbefore, in the case of forming the thin film encapsulation layer by alternately performing the forming of the inorganic layer and the forming of the organic layer in an iterative manner, a height of the barrier wall  400  may be adjusted based on the forming of the thin film encapsulation layer. 
     Hereinafter, examples of the plasma cleaning treatment in the method of manufacturing the OLED display device according to the exemplary embodiment will be described in further detail. However, the present exemplary embodiment is not limited to the following examples. 
     Inventive Example 1 
     An OLED element is formed on a substrate, and prior to forming a first inorganic layer of a thin film encapsulation layer, a plasma cleaning treatment is performed. The plasma cleaning treatment is performed on the substrate on which the OLED element is formed, and under a N 2 /N 2 O atmosphere. At the time of performing the plasma cleaning treatment herein, a degree of vacuum (e.g., a degree of pressure) is about 1.5 Torr; a flow rate of N 2  gas is about 16,000 standard cubic meters (scm); a flow rate of N 2 O gas is about 5,000 scm; a level of RF power is 3,000 W; and a period of time for the plasma cleaning treatment is about 10 s. 
     The first inorganic layer of the thin film encapsulation layer is formed on the substrate which has undergone the plasma cleaning treatment, and a first organic layer and a second inorganic layer are sequentially deposited on the first inorganic layer, such that the OLED display device is obtained. 
     Comparative Example 1 
     An OLED display device is obtained through the same scheme as that of Inventive Example 1, except that a thin film encapsulation layer is formed without performing a plasma cleaning treatment subsequently to forming an OLED element on a substrate. 
       FIGS. 8 and 9  illustrate images evaluated by a surface analysis on an adhesive area between the substrate and the thin film encapsulation layer, for example, the first inorganic layer, in the OLED display devices according to Inventive Example 1 and Comparative Example 1, respectively. 
     Referring to  FIGS. 8 and 9 , it may be appreciated that a layer separation does not occur at the adhesive area between the substrate and the first inorganic layer of the thin film encapsulation layer of the OLED display device according to Inventive Example 1 ( FIG. 8 ), while a layer separation does occur at the adhesive area between the substrate and the first inorganic layer of the thin film encapsulation layer of the OLED display device according to Comparative Example 1 ( FIG. 9 ). 
     In this regard, it may be appreciated that in the OLED display device according to Comparative Example 1, as the interfacial adhesiveness between the substrate and the thin film encapsulation layer decreases over a course of time, an adhesion defect may occur therebetween. However, in the OLED display device according to Inventive Example 1, the interfacial adhesiveness between the substrate and the thin film encapsulation layer may increase, when compared to the Comparative Example 1, and thus, such an adhesion defect may not occur therebetween. 
     As set forth above, according to one or more exemplary embodiments, the OLED display device may enhance the adhesiveness between the substrate and the thin film encapsulation layer. 
     In addition, the OLED display device may reduce or effectively prevent the external infiltration of moisture and oxygen thereinto. 
     Further, the OLED display device may enhance the product reliability in providing a foldable, flexible, or rollable display device. 
     From the foregoing, it will be appreciated that various embodiments in accordance with the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present teachings. Accordingly, the various embodiments disclosed herein are not intended to be limiting of the true scope and spirit of the present teachings.