Abstract:
An organic light-emitting display apparatus includes a substrate, a display portion on the substrate, an organic layer extending over the display portion, an inorganic layer extending over the organic layer, and a dam surrounding an outer perimeter of the organic layer. The dam may include a groove configured to accommodate a portion of the organic layer extending beyond a perimeter of the dam surrounding the organic layer. A method of manufacturing an organic light-emitting display apparatus includes forming a display portion on a substrate, forming a dam defining a groove in a region spaced from the display portion, forming an organic layer over the display portion and extending up to the region spaced from the display portion such that the organic layer is surrounded by the dam, and forming an inorganic layer over the organic layer.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2013-0158682, filed on Dec. 18, 2013, in the Korean Intellectual Property Office, the entire disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    1. Field 
         [0003]    Aspects of the present invention relate to organic light-emitting display apparatuses and methods of manufacturing the organic light-emitting display apparatuses. 
         [0004]    2. Description of the Related Art 
         [0005]    Organic light-emitting display apparatuses generally include a display portion having a structure in which an emission layer formed of an organic material is positioned between an anode electrode and a cathode electrode. When a voltage is applied to the anode electrode and the cathode electrode of the apparatuses, holes injected from each of the anode electrode and the cathode electrode are recombined with each other to generate an exciton. When the exciton changes from an excited state to a ground state, light is emitted forming an image on the apparatus. 
         [0006]    If the emission layer of the display portion comes into contact with moisture, an emission characteristic of the display portion may deteriorate, thus an encapsulation member is typically used to cover the display portion to prevent such deterioration. Thin film encapsulation in which organic layers and inorganic layers are alternately stacked is one type of encapsulation member. 
       SUMMARY 
       [0007]    One or more embodiments of the present invention relate to organic light-emitting display apparatuses. Embodiments of the present invention also relate to organic light-emitting display apparatuses having an improved structure of thin film encapsulation and methods of manufacturing the same. 
         [0008]    According to one or more embodiments of the present invention, an organic light-emitting display apparatus includes a substrate, a display portion on the substrate, an organic layer extending over the display portion, an inorganic layer extending over the organic layer, and a dam surrounding an outer perimeter of the organic layer, wherein the dam includes a groove configured to accommodate a portion of the organic layer extending beyond a perimeter of the dam surrounding the organic layer. 
         [0009]    The dam may further include a single layer surrounding the outer perimeter of the organic layer. In another embodiment, the dam may further include a plurality of layers surrounding the outer perimeter of the organic layer. 
         [0010]    The inorganic layer may extend to an outer edge of the dam. 
         [0011]    The dam may further include a bottom surface contacting the substrate, a plurality of wall surfaces integrally formed with the bottom surface and extending upward from the bottom surface, and wherein the groove may be defined by an opening surrounded by the bottom surface and the plurality of wall surfaces of the dam. 
         [0012]    According to one or more embodiments of the present invention, a method of manufacturing an organic light-emitting display apparatus includes forming a display portion on a substrate; forming a dam defining a groove in a region spaced from the display portion; forming an organic layer over the display portion and extending up to the region spaced from the display portion such that the organic layer is surrounded by the dam; and forming an inorganic layer over the organic layer. 
         [0013]    The dam may be formed of a single layer. In another embodiment, the dam may be formed of a plurality of layers. 
         [0014]    The inorganic layer may extend to and outer edge of the dam. 
         [0015]    The groove may be defined by an opening sunken from an upper surface of the dam into the inside such that a part of an outer perimeter of the organic layer is contained in the accommodated in the groove. 
         [0016]    Additional aspects will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the presented embodiments, or as appreciated by those skilled in the art. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0017]    These and/or other aspects will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which: 
           [0018]      FIG. 1  is a plan view of an organic light-emitting display apparatus, according to an embodiment of the present invention; 
           [0019]      FIG. 2  is a cross-sectional view taken along the line A-A of  FIG. 1 ; 
           [0020]      FIG. 3  is a partially expanded plan view including pixels of a display portion of the organic light-emitting display apparatus of  FIGS. 1 and 2 ; 
           [0021]      FIG. 4  is an equivalent schematic circuit diagram of one of the pixels shown in  FIG. 3 ; 
           [0022]      FIG. 5  is a cross-sectional view taken along the line B-B of  FIG. 3 ; 
           [0023]      FIG. 6  is a cross-sectional view taken along the line C-C of  FIG. 3 ; 
           [0024]      FIGS. 7A through 7D  are diagrams sequencing a process of manufacturing the organic light-emitting display apparatus of the embodiments shown in  FIGS. 1 and 2 ; and 
           [0025]      FIG. 8  is a cross-sectional view of an organic light-emitting display apparatus according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0026]    Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The present embodiments may have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by reference to the figures, to explain aspects of the present description. 
         [0027]    As used herein, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. 
         [0028]    It will be further understood that the terms “comprises” and/or “comprising” used herein specify the presence of stated features or components, but do not preclude the presence or addition of one or more other features or components. 
         [0029]    It will be understood that when a layer, region, or component is referred to as being “formed on,” or “on” another layer, region, or component, it can be directly or indirectly formed on or on the other layer, region, or component. That is, for example, intervening layers, regions, or components may also be present. 
         [0030]    Sizes of elements in the drawings may be exaggerated for convenience of explanation. In other words, since sizes and thicknesses of components in the drawings are arbitrarily illustrated for convenience of explanation, the following embodiments are not limited thereto. 
         [0031]    When a certain embodiment may be implemented differently, a specific process order may be performed differently from the described order. For example, two consecutively described processes may be performed substantially at the same time or performed in an order opposite to the described order. 
         [0032]      FIG. 1  is a plan view of an organic light-emitting display apparatus, according to an embodiment of the present invention.  FIG. 2  is a cross-sectional view taken along the line A-A of  FIG. 1 . 
         [0033]    The organic light-emitting display apparatus according to an embodiment has a structure in which a display portion  20  that displays an image is on a substrate  30  with a thin film encapsulation  10  covering and protecting the display portion  20 . 
         [0034]    The thin film encapsulation  10 , according to this embodiment, includes an organic layer  11  directly covering the display portion  20  and an inorganic layer  12  on the organic layer  11 . The organic layer  11  mainly provides flexibility to the organic light-emitting display apparatus. The inorganic layer  12  firmly prevents oxygen or moisture from permeating through to the display portion  20 . Thus, the display portion  20 , according to this embodiment, is sealed between the substrate  30  and the thin film encapsulation  10 . 
         [0035]    The organic layer  11  may be formed of a flexible organic material, for example, in some embodiments, the organic layer  11  may be formed of polyurea or polyacrylate. 
         [0036]    The inorganic layer  12  may be formed of an inorganic material having a waterproof or water-resistant characteristic. For example, in some embodiments, the inorganic layer  12  may be formed of SiNx, Al 2 O 3 , SiO 2 , or TiO 2 . 
         [0037]    In these embodiments, since the organic layer  11  of the thin film encapsulation  10  has minimal ability to prevent moisture movement as compared to the inorganic layer  12 , if an end portion of the organic layer  11  spreads to an outer edge of a region covered by the inorganic layer  12 , the result would be the creation of a path through which external moisture may permeate into the display portion  20 . Thus, the thin film encapsulation  10  may include a dam  13  for effectively regulating a range of the organic layer  11  to prevent the path of moisture movement from being created, according to an embodiment. 
         [0038]    The dam  13 , according to this embodiment, is formed outside the display portion  20  in order to regulate a region of the organic layer  11 , and may include an accommodation groove  13   a  surrounded by a floor surface  13   b  and two wall surfaces  13   c , as shown in  FIG. 2 . Thus, according to this embodiment, the dam  13 , itself, may function as a dam for preventing the organic layer  11  from spreading to the outer edge of the organic light emitting display apparatus where the inorganic layer  12  is extends, as well as containing any part of the organic layer  11  that may extend over the dam  13  in the accommodation groove  13   a  to prevent it from spreading to an outer edge. Thus, according to this embodiment, the dam  13  functions to prevent the organic layer  11  from extending to the outer edge, and the accommodation groove  13   a  functions to prevent the organic layer  11  from extending beyond the dam  13  to the outer edge. 
         [0039]    The dam  13  will be described in further detail, below. Further details of the structure of the display portion  20  will now be described. 
         [0040]    In an embodiments where the display portion  20  is expanded, multiple pixels may be present as shown in the partially expanded view in  FIG. 3 . A structure of one pixel of these multiple pixels is expressed as an equivalent schematic circuit diagram as shown in  FIG. 4 . 
         [0041]    As shown, each pixel according to this embodiment generally includes at least two thin film transistors (TFTs), including a first TFT  21  for switching and a second TFT  23  for driving, a capacitor  22 , and an organic light-emitting device  24  (hereinafter referred to as an “EL device”). 
         [0042]    The first TFT  21 , according to this embodiment, is driven by a scan signal (Scan) applied to a gate line  26 , and transmits a data line (Data) applied to a data line  27 . 
         [0043]    The second TFT  23 , according to this embodiment, determines an amount of current to enter into the EL device  24  according to the data signal Data transmitted by the first TFT  21 , i.e., a voltage difference (Vgs) between a gate and a source. 
         [0044]    The capacitor  22 , according to this embodiment, stores the data signal Data transmitted by the first TFT  21  for a frame. 
         [0045]    To implement a circuit according to this embodiment, an organic light-emitting display apparatus has a structure as shown in the embodiments of  FIGS. 3 ,  5 , and  6 , which will be described in further detail below. 
         [0046]    As shown in the embodiments of  FIGS. 3 ,  5 , and  6 , a buffer layer  111  is positioned on the substrate  30 , and the first TFT  21 , the second TFT  23 , the capacitor  22 , and the EL device  24  are positioned on the buffer layer  111 . 
         [0047]    As shown in the embodiments of  FIGS. 3 and 5 , the first TFT  21  includes a first active layer  211  on the buffer layer  111 , a gate insulating layer  112  on the first active layer  211 , and a gate electrode  212  on the gate insulating layer  112 . 
         [0048]    The first active layer  211 , according to an embodiment, may be formed as an amorphous silicon thin film or a polycrystalline silicon thin film. The first active layer  211 , according to an embodiment, includes source and drain regions doped with high concentration N type or P type impurities. Alternatively, the first active layer  211 , according to another embodiment, may be formed of an oxide semiconductor. For example, the oxide semiconductor forming the first active layer  211 , according to this embodiment, may include an oxide of a material selected from Group 12, 13, or 14 metal elements, such as zinc (Zn), indium (In), gallium (Ga), tin (Sn), cadmium (Cd), germanium (Ge), or hafnium (Hf), and any combinations thereof. For example, in one embodiment, the first active layer  211  may include G-I-Z-O [(In 2 O 3 )a(Ga 2 O 3 )b(ZnO)c] (where a, b, and c are real numbers satisfying a condition that a≧0, b≧0, and c&gt;0). 
         [0049]    The gate insulating layer  112 , according to an embodiment, is on the first active layer  211 , and the gate electrode  212  is on a predetermined region of the gate insulating layer  112 . The gate electrode  212 , according to this embodiment, is connected to the gate line  26  that applies a TFT on/off signal. 
         [0050]    In an embodiment, an inter-insulator  113  may be on the gate electrode  212 . In an embodiment, a source electrode  213  and a drain electrode  214  are respectively formed to contact the source and drain regions of the first active layer  211  through contact holes. The source electrode  213 , according to this embodiment, is connected to the data line  27  of  FIG. 3  and supplies a data signal to the first active layer  211 . The drain electrode  214 , according to this embodiment, is connected to a first charging electrode  221  of the capacitor  22  and supplies power to the capacitor  22 . 
         [0051]    According to an embodiment, a passivation layer  114 , which may be formed of an inorganic material such as SiO 2 , SiNx, etc., may be positioned on the source electrode  213  and the drain electrode  214 . A planarization layer  115 , according to an embodiment, may be formed of an acryl, polyimide, BCB, etc. material, and may be positioned on the passivation layer  114 . 
         [0052]    The capacitor  22  for charging, according to an embodiment, is between the first TFT  21  and the second TFT  23  and stores a driving voltage necessary for driving the second TFT  23  for one frame. As shown in the embodiments of  FIGS. 5 and 7 , the capacitor  22  may include a first charging electrode  221  connected to the drain electrode  214  of the first TFT  21 , a second charging electrode  222  overlapping with an upper portion of the first charging electrode  221  and electrically connected to a driving power line  25  that applies driving power, and the inter-insulator  113  between the first charging electrode  221  and the second charging electrode  222  and used as a dielectric substance. 
         [0053]    A second active layer  231 , according to an embodiment, may be on the buffer layer  111  in the second TFT  23 , as shown in  FIGS. 3 and 6 . The second active layer  231 , according to this embodiment, includes source and drain regions doped with high concentration N type or P type impurities. The second active layer  231 , according to an embodiment, may also be formed of an oxide semiconductor. For example, the second active layer  231 , according to this embodiment, may be formed of an oxide semiconductor including an oxide of a material selected from Group 12, 13, or 14 metal elements, such as zinc (Zn), indium (In), gallium (Ga), tin (Sn), cadmium (Cd), germanium (Ge), or hafnium (Hf), and any combinations thereof. For example, in one embodiment, the second active layer  231  may include G-I-Z-O [(In 2 O 3 )a(Ga 2 O 3 )b(ZnO)c] (where a, b, and c are real numbers satisfying a condition that a≧0, b≧0, and c&gt;0). In an embodiment, a second gate electrode  232  that is connected to the first charging electrode  221  of the capacitor  22  and supplies a TFT on/off signal may be on the second active layer  231  with the gate insulating layer  112  between the second active layer  231  and the second gate electrode  232 . A second source electrode  233 , according to an embodiment, may be connected to the driving power line  25  supplying a reference voltage to the second active layer  231  for driving, and a second drain electrode  234  connecting the second TFT  23  and the EL device  24  and applying driving power to the EL device  24  may be on the second gate electrode  232 , according to the embodiment. The inter-insulator  113  in this embodiment is between the second gate electrode  232 , the second source electrode  233 , and the second drain electrode  234 . The passivation layer  114 , according to this embodiment, is between the second source electrode  233  and the second drain electrode  234 , and between the first electrode  241  that is an anode electrode of the EL device  24 . 
         [0054]    The insulating planarization layer  115 , according to an embodiment, may be formed of a material such as acryl, etc, and positioned on the first electrode  241 . An opening  244  may be defined in the planarization layer  115 , and then the EL device  24  may be formed. 
         [0055]    The EL device  24 , according to an embodiment, emits red, green, and blue light according to a flow of current, and displays predetermined image information. The EL device  24 , according to this embodiment, may include the first electrode  241  that is the anode electrode connected to the second drain electrode  234  of the second TFT  23  and receives a positive power supply from the second drain electrode  234 , a second electrode  243  that is a cathode electrode configured to cover whole pixels and supplies negative power, and an emission layer  242  between the first electrode  241  and the second electrode  243  that emits light. 
         [0056]    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) may be stacked adjacent to the emission layer  242 , according to embodiments of the present invention. 
         [0057]    According an embodiment, the emission layer  242  may be separately formed for each pixel such that pixels that emit red, green, and blue light form a single unit pixel as shown in the embodiment of  FIG. 6 . Alternatively, the emission layer  242 , according to another embodiment, may be commonly formed on a whole pixel region regardless of the positions of the pixels. In this embodiment, the emission layer  242  may be formed by vertically stacking or mixing, for example, layers including an emission material that emits the red, green, and blue lights. A combination of other colors may be possible in other embodiments where the emission layer  242  may be able to emit white light. A color conversion layer that converts the emitted white light into a predetermined color or a color filter may be further included, in other embodiments. 
         [0058]    The emission layer  242 , according to these embodiments, is highly vulnerable to moisture, and thus if moisture permeates into the display portion  20 , an image forming characteristic of the organic light-emitting display apparatus may rapidly deteriorate. 
         [0059]    A structure of the organic light-emitting display apparatus according to an embodiment of the present invention will now be described with reference back to  FIGS. 1 and 2 . 
         [0060]    The display portion  20 , according to an embodiment, may be formed by using the above-described pixels as shown in  FIG. 3 . An image may be formed on the display portion  20 . In this embodiment, the TFTs  21  and  23 , the capacitors  22 , and the EL devices  24  shown in  FIGS. 3 ,  5 , and  6  may be installed in the display portion  20 . 
         [0061]    The thin film encapsulation  10  is placed over the display portion  20 , according to an embodiment, to protect the display portion  20  from external moisture and air. The thin film encapsulation  10  in this embodiment has the organic layer  11  and the inorganic layer  12  sequentially stacked. More specifically, the organic layer  11 , according to an embodiment, directly covers the display portion  20 , and the inorganic layer  12  covers the organic layer  11 . Thus, the thin film encapsulation  10  according to this embodiment in which the organic layer  11  and the inorganic layer  12  are sequentially stacked, may have both a moisture movement prevention function and flexibility function. 
         [0062]    As described above, the dam  13 , according to embodiments, may regulate a region of the organic layer  11  to prevent creation of a moisture movement path through the organic layer  11 . In these embodiments, the wall surface  13   c  of the dam  13  of the display portion  20  may prevent the organic layer  11  from extending to the outer edge, and, if a part of the organic layer  11  does extend beyond the dam  13 , allows that extension to be contained in the accommodation groove  13   a  to prevent its further extension to the outer edge. Thus, the dam  13  according to an embodiment having the above-described structure, may prevent the organic layer  11  from extending to the outer edge beyond a region covered by the inorganic layer  12 , thus, reducing the possibility of moisture movement to the display portion  20  from the outer edge through the organic layer  11 . 
         [0063]    The organic light-emitting display apparatus according to embodiments having the above-described structure may be manufactured through a process as sequenced in  FIGS. 7A through 7D . 
         [0064]    According to an embodiment, a body of the dam  13  may be formed in a region outside the display portion  20  on the substrate  30 , as shown in  FIG. 7A . In an embodiment, the dam  13  may be formed, for example, by using a deposition process using a mask, and may be formed of a material capable of patterning by exposure and etching. 
         [0065]    Next, the accommodation groove  13   a  sunken from an upper surface of the dam  13  into the inside thereof may be defined, according to an embodiment, as shown in  FIG. 7B . The accommodation groove  13   a  may be defined in the upper surface of the dam  13  after exposing and etching, for example, a corresponding region of the dam  13 . 
         [0066]    The organic layer  11  covering the display portion  20  may be formed as shown in the embodiment of  FIG. 7C . In this embodiment, a region of the organic layer  11  may be regulated by the dam  13 . If a portion of the organic layer  11  extends beyond the dam  13 , since the portion is contained in the accommodation groove  13   a , according to this embodiment, there possibility of continuously spreading the organic layer  11  to the outside edges is reduced. 
         [0067]    Next, placement of the inorganic layer  12  over the organic layer  11  and the dam  13 , as shown in the embodiment of  FIG. 7D , may complete the thin film encapsulation  10  process according to these embodiments. 
         [0068]    Therefore, the dam  13 , according to these embodiments, may effectively prevent the organic layer  11  from extending to the outer edge, such that the organic layer  11  remains entirely covered by the inorganic layer  12  having outstanding waterproof properties, and thus implement a highly stable anti-moisture movement property in the thin film encapsulation  10 . 
         [0069]    In these embodiments, an outer boundary of the organic layer  11  is strictly regulated by the dam  13  and is wholly covered by the inorganic layer  12 , thereby limiting a possibility of permeating external moisture into the display portion  20  through the organic layer  11 . Thus, a performance deterioration problem of the display portion  20  due to permeation of oxygen or moisture may be greatly avoided. 
         [0070]    Although the dam  13  may be formed in a single layer in a region outside the display portion  20 , as described in the previous embodiments, the dam  13  may also be formed in several layers, as shown in the embodiment of  FIG. 8 . In this embodiment, a possibility of the organic layer  11  extending to the outer edge may be more strictly prevented. However, in this embodiment, a dead space outside the display portion  20  may increase, and thus a width W of an overall region of the dam  13  on the substrate  30  may be large, for example up to 5 millimeters (mm) in width. 
         [0071]    It should be understood that the exemplary embodiments described herein should be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments. 
         [0072]    While one or more embodiments of the present invention have been described with reference to the figures, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention, and as further defined by the following claims.