Patent Publication Number: US-10777771-B2

Title: Display apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2018-0158383, filed on Dec. 10, 2018, in the Korean Intellectual Property Office, and entitled: “Display Apparatus,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     One or more embodiments relate to a display apparatus, and more particularly, to a display apparatus capable of effectively controlling overflow of a monomer in a narrow dead space of the display apparatus. 
     2. Description of the Related Art 
     A display apparatus is an apparatus for visually displaying data. Display apparatuses have been used for various purposes. In addition, since the thickness and weight of display apparatuses have been reduced, their range of utilization has increased. 
     A display apparatus includes a substrate that is partitioned into a display area and a non-display area outside the display area. A non-display area, in which non-display elements such as a pad portion, a plurality of wirings, a driving circuit portion, etc. are arranged, is a dead space that is not capable of realizing images. Recently, there has been increasing demand to further reduce dead spaces in display apparatuses. 
     SUMMARY 
     Embodiments are directed to a display apparatus including a substrate, a display area on the substrate, the display area including a plurality of pixels a non-display area outside the display area, a first dam surrounding the display area, a second dam outside the first dam, the second dam surrounding the first dam, a third dam between the display area and the first dam, the third dam including a first insulating layer and a second insulating layer, the second insulating layer being on the first insulating layer, and a thin film encapsulation layer covering the display area, the thin film encapsulation layer including at least one inorganic encapsulation layer and at least one organic encapsulation layer. The third dam includes a first region in which the second insulating layer is spaced along a direction in which the first insulating layer extends, and a second region in which the second insulating layer is continuously present along the direction in which the first insulating layer extends, the second region not overlapping the first region. 
     In the first region, the first insulating layer may include an extension that extends along the direction in which the first insulating layer extends, and a plurality of protrusions protruding from the extension towards the display area. 
     In the first region, a width of the first insulating layer may be greater than a width of the second insulating layer. 
     In the first region, a height from a surface of the substrate to an uppermost portion of the second insulating layer may be equal to or greater than a height from the surface of the substrate to an uppermost portion of the first dam. 
     Each of the pixels may include a first electrode, an emission layer on the first electrode, and a second electrode on the emission layer, the second electrode being arranged commonly throughout the plurality of pixels. A first power voltage line supplying a first power to each pixel may be located in the non-display area. A second power voltage line that supplies a second power to the second electrode may be spaced from the first power voltage line. 
     The first region of the third dam partially overlaps the second power voltage line. 
     The second dam may clad end portions of the second power voltage line. 
     The first dam may overlap the second power voltage line. 
     The second region of the third dam may partially overlap the first power voltage line. 
     In the second region, a width of an upper surface of the first insulating layer may be equal to a width of a lower surface of the second insulating layer. 
     In the second region, a height from a surface of the substrate to an uppermost portion of the second insulating layer may be equal to a height from the surface of the substrate to an uppermost portion of the first dam. 
     The display apparatus may further include a pixel-defining layer covering end portions of the first electrode and a spacer on the pixel-defining layer. The first insulating layer may include a same material as a material of the pixel-defining layer. The second insulating layer may include a same material as a material of the spacer. 
     A thin film transistor including an active layer, a gate electrode, a source electrode, and a drain electrode may be between each pixel and the substrate. A third insulating layer may be in the display area and the non-display area, the third insulating layer including at least one of insulating layers arranged between the active layer, the gate electrode, the source electrode, and the drain electrode. The third dam may further include the third insulating layer between the substrate and the first insulating layer. 
     The second dam may include the third insulating layer, the first insulating layer on the third insulating layer, and the second insulating layer on the first insulating layer. 
     The third insulating layer may include a first planarization layer and a second planarization layer. The first planarization layer may be in the display area and the non-display area, and the second planarization layer is on the first planarization layer. The second dam and the third dam may both include a same material as the first planarization layer and the second planarization layer. 
     The first dam may include a same material as one of the first planarization layer and the second planarization layer. 
     A height from a surface of the substrate to an uppermost portion of the second dam may be greater than a height from the surface of the substrate to an uppermost portion of the first dam. 
     Each of the at least one inorganic encapsulation layer includes a first inorganic encapsulation layer and a second inorganic encapsulation layer. Each of the at least one organic encapsulation layer may be between the at least one first inorganic encapsulation layer and the second inorganic encapsulation layer, respectively. 
     The at least one first inorganic encapsulation layer and the second inorganic encapsulation layer may be in direct contact with each other on an outer portion of the second dam. 
     The second electrode may extend to the non-display area and partially covers the first region of the third dam. 
     Embodiments are also directed to a display apparatus including a substrate, a display area on the substrate, the display area including a plurality of pixels, a non-display area outside the display area, a first dam surrounding the display area, a second dam outside the first dam, the second dam surrounding the first dam, a third dam between the display area and the first dam, the third dam including a first insulating layer and a second insulating layer on the first insulating layer, and a thin film encapsulation layer covering the display area, the thin film encapsulation layer including a first inorganic encapsulation layer, a second inorganic encapsulation layer, and an organic encapsulation layer between the first inorganic encapsulation layer and the second inorganic encapsulation layer. The first insulating layer of the third dam may include an extension that extends along the direction in which the first insulating layer extends, and a plurality of protrusions protruding from the extension towards the display area. The second insulating layer of the third dam may be on the extension in a form of dot patterns spaced apart from one another along a direction in which the first insulating layer extends. 
     The first dam and the second dam may each include the first insulating layer and the second insulating layer. The second insulating layers of the first dam and the second dam may be continuously arranged along a direction in which the first insulating layer extends. 
     Each of the plurality of pixels may include a first electrode, an emission layer on the first electrode, and a second electrode on the emission layer, the second electrode being arranged commonly throughout the plurality of pixels. The display apparatus may further include a pixel-defining layer covering end portions of the first electrode, a spacer on the pixel-defining layer, and a thin film transistor between each of the pixels and the substrate, the thin film transistor including an active layer, a gate electrode, a source electrode, and a drain electrode, a third insulating layer in the display area and the non-display area, the third insulating layer including at least one insulating layer arranged between the active layer, the gate electrode, the source electrode, and the drain electrode. The first insulating layer includes a same material as the pixel-defining layer. The second insulating layer includes a same material as the spacer. 
     The first dam and the third dam may each further include a third insulating layer between the substrate and the first insulating layer. 
     Heights from a surface of the substrate to an uppermost portion of the first dam and to an uppermost portion of the third dam may be equal to or greater than a height from the surface of the substrate to an uppermost portion of the second dam. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates a plan view of a display apparatus according to an embodiment; 
         FIGS. 2A and 2B  illustrate equivalent circuit diagrams of a pixel included in the display apparatus of  FIG. 1 ; 
         FIG. 3  illustrates a plan view of region III in  FIG. 1 ; 
         FIG. 4  illustrates a cross-sectional view of a pixel included in the display apparatus, taken along line IVA-IVB of  FIG. 3 ; 
         FIG. 5  illustrates a cross-sectional view taken along line VA-VB of  FIG. 1 ; 
         FIG. 6  illustrates a cross-sectional view taken along line VIA-VIB of  FIG. 1 ; 
         FIG. 7A  illustrates a plan view of a first portion of a third dam; 
         FIG. 7B  illustrates a perspective view of the first portion of  FIG. 7A ; 
         FIG. 8  illustrates a plan view showing another example of the first portion in the third dam; 
         FIG. 9  illustrates a plan view showing another example of the first portion in the third dam; 
         FIG. 10  illustrates a plan view of a fourth portion of a third dam; 
         FIG. 11  illustrates a plan view of a display apparatus according to another embodiment; 
         FIG. 12  illustrates a plan view of a display apparatus according to another embodiment; 
         FIG. 13  illustrates a plan view of a display apparatus according to another embodiment; 
         FIG. 14  illustrates a plan view of a display apparatus according to another embodiment; and 
         FIG. 15  illustrates a plan view of a display apparatus according to another embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. 
     In the drawing figures, the dimensions of layers and regions may be exaggerated for clarity of illustration. It will also be understood that when a layer or element is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Further, it will be understood that when a layer is referred to as being “under” another layer, it can be directly under, and one or more intervening layers may also be present. In addition, it will also be understood that when a layer is referred to as being “between” two layers, it can be the only layer between the two layers, or one or more intervening layers may also be present. Like reference numerals refer to like elements throughout. 
     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. 
     While such terms as “first,” “second,” etc., may be used to describe various components, such components are not be limited to the above terms. The above terms are used only to distinguish one component from another. 
     An expression used in the singular encompasses the expression of the plural, unless it has a clearly different meaning in the context. 
     In the present specification, it is to be understood that the terms “including or” “having” are intended to indicate the existence of the features, numbers, steps, actions, components, parts, or combinations thereof disclosed in the specification, and are not intended to preclude the possibility that one or more other features, numbers, steps, actions, components, parts, or combinations thereof may exist or may be added 
     A display apparatus is an apparatus for displaying images and may include a liquid crystal display, an electrophoretic display, an organic light-emitting display, an inorganic light-emitting display, a field emission display, a surface-conduction electron-emitter display, a plasma display, a cathode ray display, etc. Hereinafter, according to an embodiment, a display apparatus that is an organic light-emitting display apparatus is described. 
       FIG. 1  illustrates a plan view of a display apparatus  1  according to an embodiment,  FIGS. 2A and 2B  are equivalent circuit diagrams of one pixel included in the display apparatus  1  of  FIG. 1 ,  FIG. 3  illustrates a plan view of region III in  FIG. 1 ,  FIG. 4  illustrates a cross-sectional view of one pixel included in the display apparatus  1  of  FIG. 1 , taken along line IVA-IVB of  FIG. 3 ,  FIG. 5  illustrates a cross-sectional view taken along line VA-VB of  FIG. 1 , and  FIG. 6  illustrates a cross-sectional view taken along line VIA-VIB of  FIG. 1 . 
     Referring to  FIG. 1 , the display apparatus  1  includes a display area DA on a substrate  100 . The display area DA includes pixels P connected to a data line DL extending in a first direction and a scan line SL extending in a second direction intersecting with the first direction. Each of the pixels P may be connected to a driving voltage line PL extending in the first direction. 
     One pixel P may emit, e.g., red light, green light, blue light, or white light. For example, each pixel P may include an organic light-emitting diode. In addition, each pixel P may further include devices such as a thin film transistor, capacitor, etc. 
     The display area DA may provide a predetermined image using light emitted from the pixels P. A non-display area NDA may be arranged on the outside of the display area DA. For example, the non-display area NDA may surround the display area DA. 
     The non-display area NDA, in which pixels P are not arranged, does not provide images. In the non-display area NDA, a first power voltage line  10  and a second power voltage line  20  may be arranged. The second power voltage line  20  may supply a voltage that is different from that of the first power voltage line  10 . 
     The first power voltage line  10  may include a first main voltage line  11  and a first connecting line  12  arranged at a side of the display area DA. For example, when the display area DA has a rectangular shape, the first main voltage line  11  may be arranged to correspond to one of sides of the display area DA. The first connecting line  12  may extend from the first main voltage line  11  in the first direction. The first direction may be understood as a direction from the display area DA towards a terminal portion  30  located around an end portion of the substrate  100 . The first connecting line  12  may be connected to a first terminal  31  of the terminal portion  30 . 
     The second power voltage line  20  may include a second main voltage line  21  partially surrounding opposite ends of the first main voltage line  11  and the display area DA, and a second connecting line  22  extending from the second main voltage line  21  in the first direction. For example, when the display area DA has a rectangular shape, the second main voltage line  21  may extend along the opposite ends of the first main voltage line  11  and other sides of the display area DA than one side adjacent to the first main voltage line  11 . The second connecting line  22  may extend along the first direction in parallel with the first connecting line  12  and may be connected to a second terminal  32  of the terminal portion  30 . The second power voltage line  20  may be bent to surround ends of the first power voltage line  10 . 
     The terminal portion  30  may be arranged at an end portion of the substrate  100 . The terminal portion  30  may include a plurality of terminals, e.g., first to third terminals,  31 ,  32 , and  33 . The terminal portion  30  may not be covered by an insulating layer but may be exposed. The terminal portion  30  may be electrically connected to a controller such as a flexible printed circuit board, an operation driver integrated circuit (IC) chip, etc. 
     The controller may convert a plurality of image signals input from outside to a plurality of image data signals and transfer the plurality of image data signals to the display area DA via the third terminal  33 . The controller may generate control signals for controlling operations of first and second gate drivers after receiving a vertical synchronization signal, a horizontal synchronization signal, and a clock signal, and then may transfer the control signals to the first and second gate drivers via terminals. 
     The controller may transfer different voltages from each other respectively to the first power voltage line  10  and the second power voltage line  20  via the second terminal  32  and the third terminal  33 . 
     The first power voltage line  10  may provide each pixel P with a first power voltage ELVDD (see  FIGS. 2A and 2B ), and the second power voltage line  20  may provide each pixel P with a second power voltage ELVSS (see  FIGS. 2A and 2B ). 
     For example, the first power voltage ELVDD may be provided to each pixel P via the driving voltage line PL that is connected to the first power voltage line  10 . The second power voltage ELVSS may be provided to a cathode of an organic light-emitting device OLED (see  FIGS. 2A and 2B ) included in each pixel P. The second main voltage line  21  of the second power voltage line  20  may be connected to the cathode of the organic light-emitting device OLED in the non-display area NDA. 
     A scan driver providing a scan signal to the scan line SL of each pixel P, a data driver providing a data signal to the data line DL of each pixel P, etc. may be further arranged in the non-display area NDA. 
     In the non-display area NDA, a first dam  110 , a second dam  120 , and a third dam  130 , which surround the display area DA, may be spaced from one another. 
     The first dam  110  and the second dam  120  function as dams that prevent an organic material from flowing towards edges of the substrate  100  when an organic encapsulation layer  420  (see  FIG. 4 ) including the organic material such as a monomer that is also included in the thin film encapsulation layer  400  (see  FIG. 4 ) is formed by an inkjet process. The first dam  110  and the second dam  120  may prevent the generation of an edge tail at the edges of the substrate  100  due to flow of the organic encapsulation layer  420 . 
     Even with the first and second dams  110  and  120 , the organic encapsulation layer  420  could flow towards the edges of the substrate  100  beyond the first and second dams  110  and  120 . For example, if the second dam  120  were to be arranged closer to the first dam  110  than to the edge of the substrate  100  in order to reduce an area of a dead space that is visible from the outside, or if the first dam  110  were to be arranged closer to the second dam  120  in order to expand the display area DA, a distance between the first dam  110  and the second dam  120  would be reduced and the organic encapsulation layer  420  could overflow beyond the second dam  120 . The edge tail generated due to the overflow of the organic material could become an infiltration path through which external impurities could be introduced and could cause defects of the organic light-emitting device OLED. As described above, when the dead space is reduced, it becomes more desirable to reduce overflow of the organic material and to control an overflow amount of the organic material. 
     According to the embodiment, the third dam  130  is provided between the display area DA and the first dam  110  to reduce a reflow velocity of the organic material. Accordingly, an amount of the organic material flowing over the first dam  110  may be reduced. In addition, an overflowed organic material that flows towards the first dam  110  beyond the third dam  130  may be redirected back to the display area DA. Thus, the amount and location of organic material may be controlled. 
     In the embodiment, the third dam  130  may include a first portion  131  extending in the first direction along a side of the substrate  100 , a second portion  132  connected to the first portion  131  and extending in the second direction of the substrate  100 , a third portion  133  connected to the second portion  132  and extending in the first direction of the substrate  100 , and a fourth portion  134  connected to the third portion  133  and extending in the second direction of the substrate  100 . The third dam  130  will be described in more detail below. 
     Referring to  FIG. 2A , the pixel P may include a pixel circuit PC connected to the scan line SL and the data line DL and an organic light-emitting diode OLED connected to the pixel circuit PC. 
     The pixel circuit PC may include a driving thin film transistor T 1 , a switching thin film transistor T 2 , and a storage capacitor Cst. The switching thin film transistor T 2  may be connected to the scan line SL and the data line DL and may transfer a data signal Dm input through the data line DL to the driving thin film transistor T 1  according to a scan signal Sn input through the scan line SL. 
     The storage capacitor Cst may be connected to the switching thin film transistor T 2  and a driving voltage line PL and may store a voltage corresponding to a difference between a voltage transferred from the switching thin film transistor T 2  and the first power voltage ELVDD (or driving voltage) supplied to the driving voltage line PL. 
     The driving thin film transistor T 1  may be connected to the driving voltage line PL and the storage capacitor Cst and may control a driving current flowing from the driving voltage line PL to the organic light-emitting diode OLED in response to the voltage value stored in the storage capacitor Cst. The organic light-emitting diode OLED may emit light having a predetermined luminance according to the driving current. 
       FIG. 2A  shows an example in which the pixel circuit PC includes two thin film transistors and one storage capacitor. In some implementations, the pixel circuit may include a different number of thin film transistors and storage capacitor. 
     Referring to  FIG. 2B , the pixel circuit PC may include the driving and switching thin film transistors T 1  and T 2 , a compensating thin film transistor T 3 , a first initialization thin film transistor T 4 , a first emission control thin film transistor T 5 , a second emission control thin film transistor T 6 , and a second initialization thin film transistor T 7 . 
     In  FIG. 2B , every pixel P may include signal lines SLn, SLn- 1 , EL, DL, an initialization voltage line VL, and the driving voltage line PL. In some implementations, at least one of the signal lines SLn, SLn- 1 , EL, and DL, and/or the initialization voltage line VL may be shared by neighboring pixels. 
     A drain electrode of the driving thin film transistor T 1  may be electrically connected to the organic light-emitting diode OLED via the second emission control thin film transistor T 6 . The driving thin film transistor T 1  may receive the data signal Dm according to a switching operation of the switching thin film transistor T 2  to supply a driving current to the organic light-emitting diode OLED. 
     A gate electrode of the switching thin film transistor T 2  may be connected to the first scan line SLn, and a source electrode of the switching thin film transistor T 2  may be connected to the data line DL. A drain electrode of the switching thin film transistor T 2  may be connected to a source electrode of the driving thin film transistor T 1 , and at the same time, may be connected to the driving voltage line PL via the first emission control thin film transistor T 5 . 
     The switching TFT T 2  may be turned on according to the scan signal Sn received through the first scan line SLn and may perform a switching operation that transfers the data signal Dm transferred through the data line DL to the source electrode of the driving thin film transistor T 1 . 
     A gate electrode of the compensating thin film transistor T 3  may be connected to the first scan line SLn. A source electrode of the compensating thin film transistor T 3  may be connected to the drain electrode of the driving thin film transistor T 1 , and at the same time, may be connected to a pixel electrode of the organic light-emitting diode OLED via the second emission control thin film transistor T 6 . A drain electrode of the compensating thin film transistor T 3  may be connected to one electrode of the storage capacitor Cst, together with the source electrode of the first initialization thin film transistor T 4  and the gate electrode of the driving thin film transistor T 1 . The compensating thin film transistor T 3  may be turned on according to the first scan signal Sn transferred through the first scan line SLn. The compensating thin film transistor T 3  may connect the gate electrode and the drain electrode of the driving thin film transistor T 1  to each other for diode-connecting the driving thin film transistor T 1 . 
     The gate electrode of the first initialization thin film transistor T 4  may be connected to a second scan line SLn- 1  (previous scan line). The drain electrode of the first initialization thin film transistor T 4  may be connected to an initialization voltage line VL. A source electrode of the first initialization thin film transistor T 4  may be connected to one electrode of the storage capacitor Cst, together with the drain electrode of the compensating thin film transistor T 3  and the gate electrode of the driving thin film transistor T 1 . The first initialization TFT T 4  may be turned on according to a second scan signal Sn- 1  transferred through the second scan line SL- 1  to transfer an initialization voltage Vint to the gate electrode of the driving thin film transistor T 1  and to perform an initialization operation for initializing a voltage at the gate electrode of the driving thin film transistor T 1 . 
     A gate electrode of the first emission control thin film transistor  15  may be connected to an emission control line EL. A source electrode of the first emission control thin film transistor T 5  may be connected to the driving voltage line PL. A drain electrode of the first emission control thin film transistor  15  may be connected to the source electrode of the driving thin film transistor T 1  and the drain electrode of the switching thin film transistor T 2 . 
     A gate electrode of the second emission control thin film transistor T 6  may be connected to the emission control line EL. A source electrode of the second emission control thin film transistor T 6  may be connected to the drain electrode of the driving thin film transistor T 1  and the source electrode of the compensating thin film transistor T 3 . A drain electrode of the second emission control thin film transistor  16  may be electrically connected to the pixel electrode of the organic light-emitting diode OLED. The first emission control thin film transistor T 5  and the second emission control thin film transistor T 6  may be simultaneously turned on according to an emission control signal En transferred through the emission control line EL to transfer the first power voltage ELVDD to the organic light-emitting diode OLED so that a driving current may flow through the organic light-emitting diode OLED. 
     A gate electrode of the second initialization thin film transistor T 7  may be connected to the second scan line SLn- 1 . A source electrode of the second initialization thin film transistor T 7  may be connected to the pixel electrode of the organic light-emitting diode OLED. A drain electrode of the second initialization thin film transistor  17  may be connected to the initialization voltage line VL. The second initialization thin film transistor T 7  may be turned on according to the second scan signal Sn- 1  transferred through the second scan line SLn- 1  to initialize the pixel electrode of the organic light-emitting diode OLED. 
       FIG. 2B  shows an example in which the first initialization thin film transistor T 4  and the second initialization thin film transistor T 7  are connected to the second scan line SLn- 1 . In some implementations, the first initialization thin film transistor T 4  may be connected to the second scan line SLn- 1 , for example, the previous scan line, to be driven according to the second scan signal Sn- 1 , and the second initialization thin film transistor T 7  may be connected to a separate signal line (e.g., a post scan line) to be driven according to a signal transferred to the corresponding scan line. 
     Another electrode of the storage capacitor Cst may be connected to the driving voltage line PL. One electrode of the storage capacitor Cst may be connected to the gate electrode of the driving thin film transistor T 1 , the drain electrode of the compensating thin film transistor T 3 , and the source electrode of the first initialization thin film transistor  14 . 
     An opposite electrode (e.g., cathode) of the organic light-emitting diode OLED may be provided with the second power voltage ELVSS (or a common power voltage). The organic light-emitting diode OLED may emit light after receiving a driving current from the driving thin film transistor T 1 . 
     According to some implementations, the number and the circuit design transistors and the storage capacitor illustrated with reference may vary. 
     Referring to  FIGS. 3 and 4 , the region III of  FIG. 1  and the driving and switching thin film transistors T 1  and T 2  and the storage capacitor Cst of the pixel circuit PC in each pixel P illustrated above with reference to  FIGS. 2A and 2B  will be described in more detail below. 
     Referring to  FIG. 3 , the plurality of pixels P may be arranged in the region III of  FIG. 1 . The plurality of pixels P may be surrounded by a pixel-defining layer  113 . A spacer  115  may be arranged on the pixel-defining layer  113 . 
     In  FIG. 3 , the pixels P may have square shapes of the same sizes or may have different sizes and different shapes. 
     The spacer  115  may be provided between some of the plurality of pixels P. The spacer  115  may maintain a gap between a mask and the substrate  100  during a process of providing an intermediate layer  320  including an emission layer by using the mask. Thus, defects such as dents or torn portions of the intermediate layer  320  that could be caused by the presence of the mask may be prevented during a deposition process. 
     The spacer  115  may include the same material as that of the pixel-defining layer  113 . The spacer  115  may be formed to have a different height from the pixel-defining layer  113  and may be formed to have a same material as that of the pixel-defining layer  113  by using a half-tone mask simultaneously when the pixel-defining layer  113  is formed. 
     Referring to  FIG. 4 , a buffer layer  101  may be on the substrate  100 . The driving thin film transistor T 1 , the switching thin film transistor T 2 , and the storage capacitor Cst may be arranged on the buffer layer  101 . 
     The substrate  100  may include suitable materials such as glass, metal, plastic, etc. For example, the substrate  100  may include a flexible substrate including a polymer resin such as a polyethersulfone (PES), polyacrylate (PAR), polyetherimide (PEI), polyethylene naphthalate (PEN), polyethylene terephthalate (PET), polyphenylene sulfide (PPS), polyarylate, polyimide (PI), polycarbonate (PC), cellulose acetate propionate (CAP), etc. 
     The buffer layer  101  on the substrate  100  may include silicon oxide (SiOx) and/or silicon nitride (SiNx) for preventing impurities from infiltrating to the substrate  100 . 
     The driving thin film transistor T 1  may include a driving semiconductor layer A 1  and a driving gate electrode G 1 . The switching thin film transistor T 2  may include a switching semiconductor layer A 2  and a switching gate electrode G 2 . A first gate insulating layer  103  may be arranged between the driving semiconductor layer A 1  and the driving gate electrode G 1  and between the switching semiconductor layer A 2  and the switching gate electrode G 2 . The first gate insulating layer  103  may include an inorganic insulating material such as SiOx, SiNx, silicon oxynitride (SiON), etc. 
     The driving semiconductor layer A 1  and the switching semiconductor layer A 2  may include amorphous silicon or polycrystalline silicon. In some implementations, the driving semiconductor layer A 1  and the switching semiconductor layer A 2  may each include an oxide of at least one selected from the group consisting of indium (In), gallium (Ga), tin (Sn), zirconium (Zr), vanadium (V), hafnium (Hf), cadmium (Cd), germanium (Ge), chromium (Cr), titanium (Ti), and zinc (Zn). The driving semiconductor layer A 1  may be disposed apart from the switching semiconductor layer A 2  in the lateral direction. The lateral direction may be any direction between the first direction and the second direction. 
     The driving semiconductor layer A 1  may include a driving channel region that overlaps the driving gate electrode G 1  in the height direction and that is not doped with impurities. A driving source region and a driving drain region doped with impurities may be on opposite sides of the driving channel region. A driving source electrode S 1  and a driving drain electrode D 1  may be respectively connected to the driving source region and the driving drain region. 
     The switching semiconductor layer A 2  may include a switching channel region that overlaps the switching gate electrode G 2  in the height direction and that is not doped with impurities. A switching source region and a switching drain region doped with the impurities may be at opposite sides of the switching channel region. A switching source electrode S 2  and a switching drain electrode D 2  may be respectively connected to the switching source region and the switching drain region. 
     The driving gate electrode G 1  and the switching gate electrode G 2  may include Mo, Al, Cu, Ti, etc. The driving gate electrode G 1  may each have a single-layered structure or a multi-layered structure. 
     In some embodiments, the storage capacitor Cst may overlap the driving thin film transistor T 1  in the height direction. In this case, the storage capacitor Cst and the driving thin film transistor T 1  may each have an increased area and may provide high-quality images. For example, the driving gate electrode G 1  may be a first storage capacitor plate CE 1  of the storage capacitor Cst. A second storage capacitor plate CE 2  may overlap the first storage capacitor plate CE 1  in the height direction a second gate insulating layer  105  interposed therebetween. The second gate insulating layer  105  may include an inorganic insulating material such as SiOx, SiNx. SiON, etc. 
     The driving thin film transistor T 1 , the switching thin film transistor T 2 , and the storage capacitor Cst may be covered by an interlayer insulating layer  107 . 
     The interlayer insulating layer  107  may include an inorganic material such as SiON, SiOx, and/or SiNx. 
     The data line DL may be arranged on the interlayer insulating layer  107 . The data line DL may be connected to the switching semiconductor layer A 2  of the switching thin film transistor T 2  via a contact hole that penetrates through the interlayer insulating layer  107 . The data line DL may function as the switching source electrode S 2 . 
     The driving source electrode S 1 , the driving drain, electrode D 1 , the switching source electrode S 2 , and the switching drain electrode D 2  may be arranged on the interlayer insulating layer  107  and may be connected to the driving semiconductor layer A 1  or the switching semiconductor layer A 2  via the contact holes penetrating through the interlayer insulating layer  107 . 
     In addition, the data line DL, the driving source electrode S 1 , the driving drain electrode D 1 , the switching source electrode S 2 , and the switching drain electrode D 2  may be covered by an inorganic protective layer. 
     The inorganic protective layer may have a single-layered or multi-layered structure including SiNx and SiOx. The inorganic protective layer may prevent some exposed wirings in the non-display area NDA, for example, wirings formed with the data line DL through the same process, from being damaged due to an etchant that is used in patterning of a pixel electrode  310 . 
     The driving voltage line PL may be arranged at a different layer from that of the data line DL. Throughout the specification, the phrase ‘A and B are arranged at different layers’ refers to a case in which at least one insulating layer is provided between A and B, for example, where one of A and B is arranged under the at least one insulating layer and the other is arranged on the at least one insulating layer. A first planarization layer  109  may be provided between the driving voltage line PL and the data line DL. The driving voltage line PL may be covered by a second planarization layer  111 . 
     The driving voltage line PL may have a single-layered structure or a multi-layered structure including at least one selected from Al, Cu, Ti, and an alloy thereof. In an embodiment, the driving voltage line PL may have a triple-layered structure including Ti/Al/Ti. 
       FIG. 4  shows an example in which the driving voltage line PL is arranged on the first planarization layer  109 . In some implementations, the driving voltage line PL may be connected to a lower additional voltage line arranged at the same layer as that of the data line DL via a contact hole provided in the first planarization layer  109  to reduce resistance. 
     The first planarization layer  109  and the second planarization layer  111  may have a single-layered structure or a multi-layered structure. 
     The first planarization layer  109  and the second planarization layer  111  may include an organic insulating material. For example, the organic insulating material may include a general universal polymer (polymethylmethacrylate (PMMA) or polystyrene (PS)), a polymer derivative having one or more phenol groups, an acryl-based polymer, an imide-based polymer, an aryl ether-based polymer, an amide-based polymer, a fluoride-based polymer, a p-xylene-based polymer, a vinyl alcohol-based polymer, etc. 
     In some implementations, the first planarization layer  109  and the second planarization layer  111  may include an inorganic insulating material. For example, the inorganic insulating material may include SiON, SiOx, SiNx, etc. 
     The organic light-emitting diode OLED including the pixel electrode  310 , an opposite electrode  330 , and an intermediate layer  320  including an emission layer between the pixel electrode  310  and the opposite electrode  330  may be located on the second planarization layer  111 . 
     The pixel electrode  310  may be connected to a connecting line CL on the first planarization layer  109 . The connecting line CL may be connected to the driving drain electrode D 1  of the driving thin film transistor T 1 . 
     The pixel electrode  310  may be a transparent electrode or a reflective electrode. 
     When the pixel electrode  310  is a transparent electrode, the pixel electrode  310  may include a transparent conductive layer. The transparent conductive layer may include at least one selected from indium tin oxide (ITO), indium zinc oxide (IZO), zinc oxide (ZnO), indium oxide (In 2 O 3 ), indium gallium oxide, and aluminum zinc oxide (AZO). In this case, the pixel electrode  310  may further include a semi-transmissive layer, in addition to the transparent conductive layer, for improving a light efficiency. The semi-transmissive layer may include at least one selected from Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, Li, Ca, and Yb formed as a thin film of a few to tens of micrometers μm). 
     When the pixel electrode  310  is a reflective electrode, the pixel electrode  310  may include a reflective layer including Ag, Mg, Al, Pt, Pd, Au, Ni, Nd, Ir, Cr, or a combination thereof, and a transparent conductive layer arranged under and/or on the reflective layer. The transparent conductive layer may include at least one selected from the group consisting of ITO, IZO, ZnO, In 2 O 3 , and AZO. 
     According to embodiments, the pixel electrode  310  may include various materials and may have various structures, e.g., a single-layered structure or a multi-layered structure. 
     The pixel-defining layer  113  may be arranged on the pixel electrode  310 . 
     The pixel-defining layer  113  may have openings each exposing the pixel electrode  310  to define the pixels P. The pixel-defining layer  113  may increase a distance between edges of the pixel electrode  310  and the opposite electrode  330  to prevent generation of an arc at an end portion of the pixel electrode  310 . The pixel-defining layer  113  may include, for example, an organic material such as polyimide, hexamethyldisiloxane (HMDSO), etc. 
     The intermediate layer  320  may include a low-molecular weight organic material or a polymer material. 
     When the intermediate layer  320  includes the low-molecular weight organic material, the intermediate layer  320  may include a hole injection layer (HIL), a hole transport layer (HTL), an emission layer (EML), an electron transport layer (ETL), and an electron injection layer (EIL) in a single or multiple-layered structure. The intermediate layer  320  may include various organic materials, e.g., copper phthalocyanine (CuPc), N,N′-di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), and tris-8-hydroxyquinoline aluminum (Alq 3 ). The intermediate layer  320  may be formed by a suitable method, e.g., a vacuum deposition method. 
     When the intermediate layer  320  includes a polymer material, the intermediate layer  320  may have a structure including an HTL and the emission layer. The HTL may include poly(3,4-ethylenedioxythiophene) PEDOT, and the EML may include a poly-phenylenevinylene (PPV)-based or polyfluorene-based polymer material. The intermediate layer  320  may be provided by using a screen printing method, an inkjet printing method, a laser induced thermal imaging (LITI) method, etc. 
     The intermediate layer  320  may be formed integrally throughout the plurality of pixel electrodes  310  or may be patterned to correspond to each of the plurality of pixel electrodes  310 . 
     The opposite electrode  330  may be provided above the display area DA and may cover the display area DA. The opposite electrode  330  may be integrally provided throughout the plurality of organic light-emitting diodes OLED to correspond to the plurality of pixel electrodes  310 . The opposite electrode  330  may be electrically connected to a second power voltage line  20  that will be described below. 
     The opposite electrode  330  may be a transparent electrode or a reflective electrode. When the opposite electrode  330  is a transparent electrode, the opposite electrode  330  may include at least one selected from Ag, Al, Mg, Li, Ca, Cu, LiF/Ca, MgAg, and CaAg and may have a thin film type of a thickness of a few to tens of micrometers (μm). 
     When the opposite electrode  330  is a reflective electrode, the opposite electrode may include at least one selected from Ag, Al, Mg, Li, Ca, Cu, LiF/Ca, LiF/Al, MgAg, and CaAg. Various modifications may be made to the structure and material included in the opposite electrode  330 . 
     A spacer  115  may be arranged on the pixel-defining layer  113 . The spacer  115  may protrude from the pixel-defining layer  113  towards an encapsulation portion  400 . The spacer  115  may maintain a space between a mask and the substrate  100  during a process of forming the intermediate layer  320  including the emission layer using the mask. The spacer  115  may prevent the generation of defects such as denting or tearing of the intermediate layer  320  that could be caused by the use of the mask during the deposition process. 
     The spacer  115  may include an organic material such as polyimide, HMDSO, etc. The spacer  115  may be arranged on the first to third dams s  110 ,  120 , and  130  that will be described below, in order to prevent moisture infiltration and to in order to form steps of the dams. 
     The organic light-emitting diode OLED may be easily susceptible to damage by external moisture or oxygen. Accordingly, the organic light-emitting diode OLED may be covered and protected by a thin film encapsulation layer  400 . 
     The thin film encapsulation layer  400  may cover the display area DA and may extend to the outside of the display area DA. The thin film encapsulation layer  400  may include at least one organic encapsulation layer and at least one inorganic encapsulation layer. In one embodiment, the thin film encapsulation layer  400  may include a first inorganic encapsulation layer  410 , an organic encapsulation layer  420 , and a second inorganic encapsulation layer  430 . 
     The first inorganic encapsulation layer  410  may entirely cover the opposite electrode  330 . The first inorganic encapsulation layer  410  may include SiOx, SiNx, and/or SiON. 
     If desired, other layers such as a capping layer may be provided between the first inorganic encapsulation layer  410  and the opposite electrode  330 . For example, the capping layer may include one or more organic materials or inorganic materials selected from SiO 2 , SiNx, ZnO 2 , TiOx, ZrO 2 , ITO, IZO, Alq 3 , CuPc, CBP, a-NPB, and ZiO 2 , in order to improve an optical efficiency. In some implementations, the capping layer may allow the light produced by the organic light-emitting diode OLED to generate a plasmon resonance phenomenon. For example, the capping layer may include nano-particles. The capping layer may prevent the organic light-emitting diode OLED from being damaged due to heat or plasma generated during a chemical vapor deposition process or a sputtering process for forming the thin film encapsulation layer  400 . For example, the capping layer may include an epoxy-based material including at least one selected from a bisphenol typed epoxy resin, an epoxidized butadiene resin, a fluorine typed epoxy resin, and a novolac epoxy resin. 
     A layer including LiF, etc. may be provided between the first inorganic encapsulation layer  410  and the capping layer if desired. 
     The first inorganic encapsulation layer  410  may be formed along a structure thereunder. Accordingly, the first inorganic encapsulation layer  410  may have an uneven upper surface. The organic encapsulation layer  420  may cover and planarize the first inorganic encapsulation layer  410 . The organic encapsulation layer  420  may planarize the upper surface of a portion corresponding to the display area DA. 
     The organic encapsulation layer  420  may include polyethylene terephthalate, polyethylene naphthalate, polycarbonate, polyimide, polyethylene sulfonate, polyoxymethylene, polyarylate, hexamethyl disiloxane, an acryl-based resin (e.g., polymethyl methacrylate, polyacrylic acid, etc.), or a combination thereof. 
     The second inorganic encapsulation layer  430  may cover the organic encapsulation layer  420 . The second inorganic encapsulation layer  430  may include SiOx, SiNx, and/or SiON. A second inorganic encapsulation layer  430  may be deposited at an edge area of a display apparatus  1  to directly contact a first inorganic encapsulation layer  410  so that an organic encapsulation layer  420  is not exposed to an outer portion of the display apparatus (see  FIG. 5 ). 
     Referring to  FIG. 5 , a left portion of the drawing shows a structure of the pixel P of  FIG. 4 , and a right portion of the drawing shows a cross-section taken along a line VA-VB of  FIG. 1 . 
     In the cross-section taken along the line VA-VB, the buffer layer  101 , the first gate insulating layer  103 , the second gate insulating layer  105 , and the interlayer insulating layer  107  are arranged on the substrate  100 , and a first conductive layer SD 1  and a second conductive layer SD 2  are arranged on the interlayer insulating layer  107 . 
     The first conductive layer SD 1  may include the same material as that of the data line DL. The second conductive layer SD 2  may include the same material as that of the driving voltage line PL. The first conductive layer SD 1  may extend towards the end portion of the substrate  100  after passing through a boundary of a hole H 1  formed in the first planarization layer  109  to be connected to the second conductive layer SD 2 . The second conductive layer SD 2  may be partially in contact with a connecting layer  310   a  including the same material as that of the pixel electrode  310  and the opposite electrode  330  extending from the display area DA at a connecting portion CNT. The first conductive layer SD 1  and the second conductive layer SD 2  may form the first power voltage line  10  supplying the first power voltage ELVDD to each pixel P. 
     The first portion  131  of the third dam  130  may be arranged at a location that partially overlaps the first power voltage line  10  in the height direction. The first dam  110  and the second dam  120  may be sequentially arranged from the first portion  131  of the third dam  130  towards the end portion of the substrate  100 . 
     The first portion  131  of the third dam  130  (see  FIG. 11 ) may include a first layer  109 - 3  including the same material as that of the first planarization layer  109 , a second layer  111 - 3  including the same material as that of the second planarization layer  111 , a third layer  113 - 3  including the same material as that of the pixel-defining layer  113 , and a fourth layer  115 - 3  including the same material as that of the spacer  115 . 
     The first dam  110  may include a first layer  111 - 1  including the same material as that of the second planarization layer  111 , a second layer  113 - 1  including the same material as that of the pixel-defining layer  113 , and a third layer  115 - 1  including the same material as that of the spacer  115 . 
     The second dam  120  may include a first layer  109 - 2  including the same material as that of the first planarization layer  109 , a second layer  111 - 2  including the same material as that of the second planarization layer  111 , a third layer  113 - 2  including the same material as that of the pixel-defining layer  113 , and a fourth layer  115 - 2  including the same material as that of the spacer  115 . 
     In the first portion  131  of the third dam  130 , the third layer  113 - 3  may extend in the first direction and the fourth layer  115 - 3 , for example, the uppermost layer in a height direction may be arranged as dot patterns spaced from one another in the first direction. 
     Referring to  FIGS. 7A and 7B , structures of the third and fourth layers  113 - 3  and  115 - 3  in the first portion  131  of the third dam  130  will be described in detail below. 
     The third layer  113 - 3  may include an extension  113 - 3   a  extending in a direction and a plurality of protrusions  113 - 3   b  protruding from the extension  113 - 3   a  towards the display area DA. The protrusions  113 - 3   b  of the third layer  113 - 3  may form concavo-convex patterns to reduce a velocity of a flow of organic material, for example, organic material that may flow when an organic encapsulation member  420  is formed. 
     The fourth layer  115 - 3  may be arranged on the extension  113 - 3   a  of the third layer  113 - 3  with a predetermined distance X 1 . The fourth layer  115 - 3  spaced above the extension  113 - 3   a  may be formed as dot patterns. While patterning the fourth layer  115 - 3  as the dot patterns, a width W 2  of the fourth layer  115 - 3  may be less than a width W 1  of the extension  113 - 3   a  of the third layer  113 - 3 . 
     The fourth layer  115 - 3  may entirely increase a height of the third dam  130 . Accordingly, a reflow velocity of an organic layer such as a monomer proceeding from the display area DA towards the end portion of the substrate  100  may be reduced around the dot patterns. Also, at a region where the fourth layer  115 - 3  is spaced by the predetermined distance X 1 , an overflowed organic material that moves towards the first dam  110  may be forced to flow back to the display area DA. Therefore, an amount of the organic material flowing towards the first dam  110  and a backflow of the organic material may the amount of the organic material to be controlled. 
     Referring to  FIGS. 8 and 9 , examples of the first portion  131  of the third dam  130  will be described below. 
     Referring to  FIG. 8 , each of the dot patterns of the fourth layer  115 - 3  in the third dam  130  may have various shapes, e.g., a shape with rounded corners  115 - 31 , a square shape  115 - 32 , a triangle shape  115 - 33 , etc. Referring to  FIG. 9 , some of the dot patterns of the fourth layer  115 - 3  may be connected to each other via a connecting portion  115 - 3   a.    
     The fourth layer  115 - 3  may be modified variously provided that the fourth layer  115 - 3  has patterns spaced from one another by a predetermined distance. 
     A height from a surface of the substrate  100  to an uppermost portion of the third dam  130 , that is, an upper surface of the fourth layer  115 - 3 , may be equal to or greater than a height to an uppermost portion of the first dam  110 , that is, an upper surface of the third layer  115 - 1 . The height of the third dam  130  may be equal to or greater than that of the first dam  110 . Accordingly, the reflow velocity of the organic material may be reduced. In addition, even when the height of the third dam  130  were to be equal to or greater than that of the first dam  110 , the backflow of the organic material could still be allowed because of the effects of the dot patterns in the uppermost layer of the third dam  130 . Thus, the organic material that flows to the first dam  110  may be prevented from being trapped between the first dam  110  and the second dam  120 . 
     In addition, generation of an edge tail due to the organic encapsulation layer  420  flowing beyond the second dam  120  may be prevented by setting a height of the second dam  120  to be greater than that of the first dam  110 . Defects such as denting or tearing of the intermediate layer  320  due to use of the mask during the deposition process may be prevented by maintaining the distance between the mask and the substrate  100  in the deposition process of the intermediate layer  320 . 
     In addition, the first layer  109 - 2  of the second dam  120  may clad the end portions of the first conductive layer SD 1  of the first power voltage line  10 , and the second layer  111 - 2  of the second dam  120  may clad the end portions of the second conductive layer SD 2  of the first power voltage line  10  to prevent degradation of the conductive layers. 
     The second portion  132  and the third portion  133  of the third dam  130  may have the same structures as that of the first portion  131 . 
     Referring to  FIG. 6 , a left portion of the drawing shows a structure of the pixel P of  FIG. 4 , and a right portion of the drawing shows a cross-section taken along a line VIA-VIB of  FIG. 1 . 
     In the cross-section taken along the line VIA-VIB, the buffer layer  101 , the first gate insulating layer  103 , and the second gate insulating layer  105  may be arranged on the substrate  100 . A plurality of spider lines SPL may be provided on the second gate insulating layer  105 . The plurality of spider lines SPL may extend from a driving circuit portion towards the terminal portion  30  (see  FIG. 1 ) and may be spaced from one another. 
     The plurality of spider lines SPL may include the same material as that of the second storage capacitor plate CE 2  of the storage capacitor Cst. 
     The interlayer insulating layer  107  may cover the spider lines SPL on the second gate insulating layer  105 . The first power voltage line  10  and the second power voltage line  20  may be arranged on the interlayer insulating layer  107 . 
     The first power voltage line  10  and the second power voltage line  20  may include the same material as that of the data line DL. In  FIG. 6 , the first power voltage line  10  and the second power voltage line  20  are shown as being single conductive layers, respectively. In some implementations, the first power voltage line  10  and/or the second power voltage line  20  may include two conductive layers connected to each other. For example, the first power voltage line  10  and/or the second power voltage line  20  may include the first conductive layer including the same material as that of the data line DL and the second conductive layer including the same material as that of the driving voltage line PL. The first conductive layer and the second conductive layer may be connected to each other via a conductive layer formed in the first planarization layer  109 . 
     The fourth portion  134  of the third dam  130  may be arranged at a location that overlaps the first power voltage line  10  in the height direction. The first dam  110  and the second dam  120  may be sequentially arranged from the fourth portion  134  of the third dam  130  towards the end portion of the substrate  100 . 
     The fourth portion  134  of the third dam  130  may include a first layer  111 - 3  including the same material as that of the second planarization layer  111 , a second layer  113 - 3  including the same material as that of the pixel-defining layer  113 , and a third layer  115 - 3  including the same material as that of the spacer  115 . 
     The first dam  110  may include a first layer  111 - 1  including the same material as that of the second planarization layer  111 , a second layer  113 - 1  including the same material as that of the pixel-defining layer  113 , and a third layer  115 - 1  including the same material as that of the spacer  115 . 
     The second dam  120  may include a first layer  109 - 2  including the same material as that of the first planarization layer  109 , a second layer  111 - 2  including the same material as that of the second planarization layer  111 , a third layer  113 - 2  including the same material as that of the pixel-defining layer  113 , and a fourth layer  115 - 2  including the same material as that of the spacer  115 . 
     Unlike the first portion  131  of the third dam  130  described above, in the fourth portion  134  of the third dam  130 , the second layer  113 - 3  including the same material as that of the pixel-defining layer  113  may extend along the second direction, and the third layer  115 - 3 , which is the uppermost layer in the height direction, may be successively arranged along the second direction. 
     Referring to  FIG. 10 , the second layer  113 - 3  in the fourth portion  134  of the third dam  130  may be formed without including a protrusion protruding towards the display area DA. The third layer  115 - 3  may be continuously arranged along the extending direction of the second layer  113 - 3  without a gap. 
     In the embodiment, the fourth portion  134  of the third dam  130  may be provided between the display area DA and the terminal portion  30 . Various elements such as the first power voltage line  10 , the second power voltage line  20 , the spider lines SPL, and the plurality of terminals  31 ,  32 , and  33  may be arranged between the display area DA and the terminal portion  30 . Accordingly, a space for additionally forming the third dam  130  may be narrow. However, the second layer  113 - 3  and the third layer  115 - 3  in the fourth portion  134  of the third dam  130  extend along the second direction without a particular pattern. Accordingly, the dam may be arranged within a narrow space. The reflow velocity of the organic layer such as the monomer flowing from the display area DA to the terminal portion  30  may be reduced by the fourth portion  134  of the third dam  130 . 
     The fourth portion  134  of the third dam  130  may partially overlap the first power voltage line  10  in the height direction. The first layer  111 - 3  may clad the end portion of the first power voltage line  10  to prevent degradation of the first power voltage line  10 . In addition, the second layer  113 - 3  in the fourth portion  134  of the third dam  130  may be formed to clad an upper surface and side surfaces of the first layer  111 - 3  in order to ensure a processing margin when patterning the second layer  113 - 3  and the third layer  115 - 3  during a photolithography process. Thus, the heights of the second layer  113 - 3  and the third layer  115 - 3  may be stably ensured. 
     In the fourth portion  134  of the third dam  130 , the second layer  113 - 3  and the third layer  115 - 3  may be formed in a process using the same mask. A width of an upper surface of the second layer  113 - 3  and a width of a lower surface of the third layer  115 - 3  may be substantially the same as each other. 
     In addition, generation of an edge tail due to an organic material forming the organic encapsulation layer  420  flowing beyond the second dam  120  may be prevented by setting a height of the second dam  120  to be greater than the height of the first and third dams  110  and  130 . Defects such as denting or tearing of the intermediate layer  320  due to the presence of the mask during the deposition process may be prevented by maintaining the distance between the mask and the substrate  100  in the deposition process of the intermediate layer  320  by using the mask. 
     The first layer  109 - 2  of the second dam  120  may clad end portions of the second power voltage line  20  to prevent degradation of the conductive layer. 
     In the display apparatus  1  according to the above embodiment, the uppermost insulating layer of the third dam  130  in the height direction may have dot patterns at left, right, and upper sides, that is, three surfaces of the substrate  100 . The uppermost insulating layer in the height direction of the fourth portion  134  of the third dam  130 , located at a lower side of the substrate  100 , for example, a side of the substrate  100  including the terminal portion  30 , may be integrally formed without a dot pattern. In some implementations, the third dam  130  may vary. 
     Hereinafter, a display apparatus according to an embodiment will be described below with reference to  FIGS. 11 to 15 . Differences from the display apparatus  1  according to the above embodiment will be described below. 
     Referring to  FIG. 11 , a display apparatus  2  according to an embodiment may include the third dam  130 , the first dam  110 , and the second dam  120  on the substrate  100 . 
     The third dam  130  may include the first portion  131  at a right side of the substrate  100 , the second portion  132  at an upper side of the substrate  100 , the third portion  133  at a left side of the substrate  100 , and the fourth portion  134  at a lower side of the substrate  100 . Unlike the above embodiment, the uppermost insulating layer in the height direction of the third dam  130  may include dot patterns on all of the boundaries of the substrate  100 . 
     Referring to  FIG. 12 , a display apparatus  3  according to an embodiment may include the third dam  130 , the first dam  110 , and the second dam  120  on the substrate  100 . 
     The third dam  130  may include the first portion  131  at a right side of the substrate  100 , the second portion  132  on an upper side of the substrate  100 , the third portion  133  at a left side of the substrate  100 , and the fourth portion  134  at a lower side of the substrate  100 . In the embodiment, on a pair of boundaries facing each other of the substrate  100 , that is, left and right sides of the substrate  100 , the uppermost insulating layer in the height direction of the third dam  130  may be formed as dot patterns. On another pair of boundaries facing each other, that is, upper and lower sides of the substrate  100 , the uppermost insulating layer in the height direction of the third dam  130  may be integrally formed without the dot patterns. 
     In some implementations, the uppermost insulating layer in the height direction of the third dam  130  may be formed as the dot patterns on the upper and lower sides of the substrate  100 . The uppermost insulating layer in the height direction of the third dam  130  may be integrally formed without the dot patterns on the left and right sides of the substrate  100 . 
     In some implementations, the dot patterns may be formed on neighboring boundaries of the substrate  100 , for example, the left and upper sides, the upper and right sides, the right and lower sides, and the lower and left sides, and on remaining regions, the uppermost insulating layer in the height direction of the third dam  130  may be integrally formed without the dot patterns. 
     Referring to  FIG. 13 , a display apparatus  4  according to another embodiment includes the third dam  130 , the first dam  110 , and the second dam  120  on the substrate  100 . 
     The third dam  130  includes the first portion  131  at a right side of the substrate  100 , the second portion  132  on an upper portion of the substrate  100 , the third portion  133  at a left side of the substrate  100 , and the fourth portion  134  at a lower side of the substrate  100 . In the embodiment, the dot patterns of the uppermost insulating layer in the height direction of the third dam may be only formed on one surface of the substrate  100 , for example, the left side of the substrate  100 . On the remaining three surfaces, for example, the right, lower, and upper sides of the substrate  100 , the uppermost insulating layer in the height direction of the third dam  130  may be formed integrally without the dot patterns. In some implementations, the dot patterns may be formed at the uppermost insulating layer in the height direction of the third dam  130  on one of the boundaries of the substrate  100 . 
     Referring to  FIG. 14 , a display apparatus  5  according to another embodiment may include a third dam  130 , a first dam  110 , and a second dam  120  on the substrate  100 . The display apparatus  5  may be a circular display, and an uppermost insulating layer in the height direction of the third dam  130  may be formed as dot patterns on an entire circular boundary. 
     In the third dam  130  of the embodiment, an insulating layer of a next uppermost layer in the height direction may extend along a circumferential direction and an uppermost insulating layer in the height direction may be formed as dot patterns on the next uppermost insulating layer extending in the circumferential direction, like in the first portion  131  of the third dam  130  according to the above embodiment. 
     Referring to  FIG. 15 , a display apparatus  6  according to an embodiment may include a third dam  130 , a first dam  110 , and a second dam  120  on the substrate  100 . 
     The display apparatus  6  may be a circular display, in which the third dam  130  is arranged along a circumference. A portion  135  of the third dam may include an uppermost insulating layer in the height direction including dot patterns and remaining portion  136  of the third dam  130  may include an uppermost insulating layer in the height direction formed integrally without dot patterns. 
     In the display apparatuses  2 ,  3 ,  4 ,  5 , or  6  illustrated in  FIGS. 11 to 15 , the third dam having an uppermost insulating layer in the height direction formed as dot patterns may be provided between the display area and the first dam to reduce a reflow velocity of organic material when forming the organic encapsulation layer. The dot patterns may allow organic material that flows to the first dam  110  to be flowed back as backflow to the display area. Thus, an amount of the organic material may be controlled. 
     According to the embodiments, the third dam having a height that is equal to or greater than that of the first dam may be provided between the display area and the first dam, and thus, the flow velocity of the organic material may be reduced. 
     Also, the uppermost layer in the height direction of the third dam may be formed to have dot patterns that are spaced from one another to cause the organic material to flow back to the display area. Thus, overflow of the organic material within a narrow dead space may be effectively controlled. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope thereof as set forth in the following claims.