Patent Document

BACKGROUND OF THE INVENTION  
       [0001]     This application claims the priority of Korean Patent Application No. 2003-80539 filed on Nov. 14, 2003, in the Korean Intellectual Property Office, which is herein incorporated by reference.  
         [0002]     1. Field of the Invention  
         [0003]     The present invention relates to a super-thin, organic, light-emitting display (OLED) having a super thin glass substrate and a method for manufacturing the same.  
         [0004]     2. Description of the Related Art  
         [0005]     Planarized display devices, such as an OLED or a thin film transistor liquid crystal display (TFT-LCD), can be formed in super thin and flexible structures. A super thin and flexible planarized display device may be produced using a flexible substrate, typically formed of a synthesized resin. However, the thickness of the substrate is maintained in a conventional thickness range because there is significant risk that the synthesized substrate, or thin film layers formed on it, will be deformed during the complicated manufacturing processes.  
         [0006]     Conventional flexible planarized display devices typically bind a highly flexible substrate to a transparent substrate using organic thin films. One thin film is formed on one substrate, another on the other substrate. The two films are then aligned, placed in contact with each other, and sealed to bond the films together. A significant disadvantage associated with producing OLEDs in this manner is that aligning the organic thin films is difficult, not only because the thin films are manufactured separately, but also because it is nearly impossible to tightly adhere thin films that have the same or a similar predetermined pattern.  
         [0007]     Various conventional solutions have been proposed, but in each the thickness of the substrate is maintained in a conventional range, which typically exceeds 0.5 mm, because the substrate must have a predetermined strength and temperature resistance to withstand the complicated processes used to from a thin film layers (at least one or more of which may be an organic film) on the substrate. Glass materials have been used to form conventional OLED substrates, but the thickness of these substrates could not be reduced to less than 0.5 mm, due to the fabrication constraints described above.  
       SUMMARY OF THE INVENTION  
       [0008]     The present invention provides a flat panel display that includes a glass substrate, an organic light-emitting part, and a sealing part. The organic light-emitting part includes one or more organic light-emitting devices (OLED) formed on a surface of the glass substrate, which has a thickness of about 0.05 mm to about 0.5 mm. The sealing part seals the organic light-emitting part and protects it from damage during the manufacturing process. A method for manufacturing the flat panel display comprises preparing a glass substrate of approximately 0.7 mm thickness or greater; forming a plurality of organic light-emitting devices on a surface of the substrate, wherein the organic light-emitting part comprises a grouping of one or more of the plurality of organic light-emitting devices; sealing each organic light-emitting part; and etching the glass substrate to a predetermined thickness.  
         [0009]     In another embodiment, the OLED includes a glass substrate of approximately 0.05 mm to approximately 0.5 mm thickness, an organic light emission layer in contact with a surface of the glass substrate, and a sealing part to seal the organic light emission layer. A first electrode is formed on one side of the organic light emission layer, and a second electrode is formed on a second side of the organic light emission layer. The sealing part is a stacked film which includes at least a barrier layer and a polymer layer. The flat panel display may further include a circular polarized film attached to an outer surface of the sealing part.  
         [0010]     An embodiment of a flat panel display having front and back viewing areas on which the same or different pictures can be displayed substantially simultaneously, together with various methods of manufacture, are also disclosed. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0011]      FIG. 1  is a cross-sectional view of an OLED configured in accordance with an embodiment of the present invention.  
         [0012]      FIG. 2  is a cross-sectional view of a sealing part shown in  FIG. 1 .  
         [0013]      FIG. 3  is a cross-sectional view of an example of an OLED light-emitting part is shown in  FIG. 1 .  
         [0014]      FIG. 4  is a cross-sectional view of another example of the OLED light-emitting part in  FIG. 1 .  
         [0015]      FIGS. 5A, 5B ,  5 C,  5 D,  5 E and  5 F are cross-sectional views illustrating a method of manufacturing the OLED of  FIG. 1 .  
         [0016]      FIGS. 6 and 7  are cross-sectional views illustrating different embodiments of the manufacturing steps described with reference to  FIG. 5D .  
         [0017]      FIG. 8  is a cross-sectional view of an OLED configured in accordance with an embodiment of the present invention.  
         [0018]      FIG. 9  is a cross-sectional view of an OLED configured in accordance with yet another embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0019]      FIG. 1  is a cross-sectional view of an OLED configured in accordance with an embodiment of the present invention.  
         [0020]     Referring to  FIG. 1 , the organic light-emitting device (OLED) includes a transparent glass substrate  1 , an organic light-emitting part  2 , and a sealing part  3  that seals the organic light-emitting part  2 .  
         [0021]     In one embodiment of the present invention, the sealing part  3  can include at least a barrier layer and at least a polymer layer. However, as seen in  FIG. 2 , the sealing part  3  can also include a polymer layer  32  inserted between a barrier layers  31  and  33 .  
         [0022]     The barrier layers  31  and  33  that constitute a sealing part  3  can be formed of a transparent blocking material, but are not necessarily limited thereto. The barrier layer can be formed of a material selected from a metal oxide, a metal nitride, a metal carbide, a metal oxynitride, and a compound of these materials. The metal oxide can be an oxide selected from silica, alumina, titania, indium oxide, tin oxide, indium tin oxide, and a compound of these materials. The metal nitride can be an aluminum nitride, a silicon nitride, and a compound of these materials. The metal carbide can be a silicon carbide, and the metal oxynitride can be a silicon oxynitride. Other inorganic materials, such as silicon, that block penetration of moisture or oxygen can also be used as material for the barrier layer.  
         [0023]     These barrier layers can be formed using a chemical or vacuum deposition method. However, when a barrier layer is formed using a vacuum deposition method, pores in the barrier layer can grow. To prevent pores from growing, a polymer layer may be formed on the barrier layer. The polymer layer may be formed of a polymer selected from an organic polymer, an inorganic polymer, an organometallic polymer, and a hybrid organic/inorganic polymer.  
         [0024]     It is understood that the sealing part  3  can be formed in a variety of forms other than the structure described above, including a super thin sealing part  3  formed in thin films. Other thin films that from a sealing part in a super thin structure may also include a polymer layer and a barrier layer, as described above.  
         [0025]     The organic light-emitting part  2  includes an organic light-emitting device, and can be a region for defining a predetermined image. In an exemplary embodiment, the organic light-emitting device is a pixel. The organic light-emitting device can be either a passive matrix organic light-emitting device (PMOLED) or an active matrix organic light-emitting device (AMOLED) having a thin film transistor.  
         [0026]      FIG. 3  shows an example of a PMOLED. The PMOLED includes a glass substrate  1 , a stripe-patterned first electrode layer  21  formed on the glass substrate  1 , as well as an organic layer  23  and a second electrode layer  24  sequentially formed on the first electrode layer  21 . In another embodiment, an insulating layer  22  can further be formed between each pattern line of the first electrode layer  21 . Similarly, the second electrode layer  24  can be formed in a pattern substantially orthogonal to the pattern of the first electrode layer  22 . The organic layer  23  can be formed of a polymer or non-polymer organic layer.  
         [0027]     When using a non-polymer organic layer, the organic layer  23  can be single-layered or multi-layered. An exemplary multi-layered organic layer  23  includes 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). Organic materials that may be used are copper phthalocyanine (CuPc), N,N′-Di(naphthalene-1-yl)-N,N′-diphenyl-benzidine (NPB), or tris-8-hydroxyquinoline aluminum (Alq3), but are not limited thereto. The non-polymer organic layer can also be formed using a vacuum deposition method.  
         [0028]     When using a polymeric organic layer, the organic layer  23  can be formed of a HTL and an EML. In this case, the HTL can be formed of PEDOT (poly(3,4-ethylenedioxythiophene), and the EML can be formed of a Poly-Phenylenevinylene (PPV) and Polyfluorene. A screen printing method or an ink jet printing method can be used for forming these layers.  
         [0029]     In one embodiment, the first electrode layer  21  performs as an anode, and the second electrode layer  24  performs as a cathode. Naturally, the function of these electrodes can be reversed.  
         [0030]     In one embodiment, the organic light-emitting device is a rearward light-emitting device. In such a case, the first electrode layer  21  is an electrode formed of a transparent conductive material such as, but not limited to, indium tin oxide (ITO). When the organic light-emitting device is a frontal light-emitting device, the second electrode layer  24  is formed by depositing ITO, or similar transparent conductive material, on a semi-transparent thin film made of Magnesium-Silver (Mg—Ag) or similar metal or metal alloy.  
         [0031]      FIG. 4  shows an example of an AMOLED. At this point, it should be noted that the pixels of the organic light-emitting part  2  of  FIG. 1 , have the same thin film transistor (TFT) structure and electrode (EL) device (OLED), as depicted in  FIG. 4 . The TFT configuration of  FIG. 4 , however, is not necessarily limited to that shown, but may vary depending on the embodiment.  
         [0032]     Referring again to  FIG. 4 , a buffer layer  11  formed of SiO 2  is formed on a glass substrate  1 , and a TFT is formed on the buffer layer  11 .  
         [0033]     The TFT has an active layer  12  formed on the buffer layer  11 , a gate insulating film  13  formed on the active layer  12 , and a gate electrode  14  formed on the gate insulating film  13 .  
         [0034]     The active layer  12  can be formed of an amorphous silicon thin film or polycrystalline silicon thin film. The active layer  12  has a source region and a drain region heavily doped with an n-type or a p-type dopant, respectively.  
         [0035]     A gate insulating film  13  is formed on the active layer  12 , and a gate electrode  14  formed of a conductive film made of MoW or aluminum/ copper (Al/Cu) is formed on a predetermined region on the gate insulating film  13 . The gate electrode  14  is connected to a gate line that applies an on/off signal to the TFT. The region for forming the gate electrode  14  corresponds to a region for forming a channel region of the active layer  12 .  
         [0036]     An interinsulating layer  15  is formed on the gate electrode  12 , and a source electrode  16  and a drain electrode  17  are respectively connected through contact holes to the source region and the drain region formed on the active layer  12 .  
         [0037]     A passivation film  18  formed of SiO 2  covers the source electrode  16  and the drain electrode  17 , and a planarized film  19  formed of acryl or polyimide is formed on the passivation film  18 . The planarized film  19  covers a portion of a lower electrode  21 . As shown, the planarized film  19  includes a opening therein, which serves as a via. A lower electrode  21  forms the bottom of the opening. An organic emission layer  23  is formed within the opening in contact with surfaces of the planarized film  19  which from a sides of the opening, and in contact with an upper surface of the lower electrode  21 . An upper electrode  24  is formed on a surface of the planarization film  19  and the organic emission layer  21 . The TFT is connected to at least a capacitor (not shown) and to a power source. The drain electrode  17  is connected to the first electrode layer (lower electrode)  21  which, in this embodiment, is an anode of the OLED.  
         [0038]     In use, variable current passing between the lower electrode  21  and the upper electrode  24  energizes the organic emission layer  23 , causing it to emit various wavelengths (and colors) of light in approximate proportion to the amount of current received. In one embodiment, the organic emission layer  23  can emit one of a red (R), green (G), or blue (B) color to display predetermined image information.  
         [0039]     As shown in  FIG. 4 , the first electrode layer (lower electrode)  21  is connected to the drain electrode  17  of the TFT and receives a positive power source therefrom. The second electrode layer (upper electrode)  24  covers whole pixels and supplies a negative power source. The organic layer  23 , which emits light in response to current supplied thereto, is disposed between the first electrode  21  and second electrode  24 .  
         [0040]     The first electrode layer  21  can be formed of a transparent conductive material such as, but not limited to indium tin oxide (ITO). If the OLED is a rear light-emitting device, the second electrode layer  24  can be formed such that it emits light toward the glass substrate  1 . In such an embodiment, the second electrode layer  24  can be formed by depositing Al/LiF on the entire surface.  
         [0041]     If the OLED is a front light-emitting device, the layer  24  can be formed by depositing indium tin oxide (ITO) on a semi-transparent thin film formed of Magnesium-Silver (Mg—Ag). The second electrode layer  24  need not necessarily be formed by depositing its formation material on the entire surface of the substrate or a layer thereof, but rather can be formed in variety of patterns. As mentioned previously, the first electrode layer  21  and the second electrode layer  24  can be configured to have reverse positions and functions.  
         [0042]     As shown in  FIG. 1 , an OLED configured in accordance with an embodiment of the present invention has a thickness of approximately 0.05 mm to approximately 0.5 mm. Because a glass substrate  1  of this approximate thickness is super-thin, there is a risk that deformation of the substrate  1  will occur if the conventional manufacturing processes described above are used. To prevent or reduce deformation, an embodiment of the present invention uses an etching process to from a glass substrate  1  to a super-thin thickness of approximately 0.05 mm to approximately 0.5 mm.  
         [0043]     Hereinafter, a method for manufacturing the OLED according to one embodiment of the present invention will be described.  
         [0044]     Referring to  FIG. 5A , a transparent glass substrate  10  is prepared. The thickness T of the transparent glass substrate  10  is sufficiently thick so that the transparent glass substrate  10  has sufficient structural strength to prevent pattern or reduce deformation of the organic light-emitting part during image formation and to prevent or reduce damages or defects during the manufacturing process. In one embodiment of the present information, the thickness T of the transparent glass substrate  10  can be more than 0.7 mm.  
         [0045]     Referring to  FIG. 5B , a plurality of organic light-emitting parts  2  are formed on the transparent glass substrate  10 . The organic light-emitting parts  2  are identical in configuration and function as the organic light-emitting parts  2  described with reference to  FIGS. 1, 2 ,  3  and  4 .  
         [0046]     Referring to FIG. SC, the organic light-emitting parts  2  are sealed by sealing parts  3 . The sealing parts  3  can be formed in the thin films as described above.  
         [0047]     After forming the sealing parts  3 , the plurality of organic light-emitting parts  2  are sealed by a sealing glass  50  ( FIG. 5D ). Then a sealing material  51  is applied on edges of the organic light-emitting part region, and the sealing glass  50  is bonded to the sealing material  51 . In this manner, the transparent glass substrate  10  and the sealing glass  50  are bonded and sealed on the edge regions by the sealing material  51 .  
         [0048]     Referring to  FIG. 5E , after sealing the transparent glass substrate  10 , the product is immersed in a basin  52  which contains a predetermined etching solution  53 . The etching solution can be fluoric acid, hydrochloric acid, or similar etching material. Over time, the etching solution reduces the thickness T of the transparent glass substrate  10  to a value of approximately 0.05 mm approximately 0.5 mm.  
         [0049]     Referring to  FIG. 5F , upon completing the etching of the transparent glass substrate  10 , the sealing glass  50  and the glass substrate  10  are simultaneously, or nearly simultaneously, cut at predetermined cutting points, which may vary, depending on how the organic light-emitting parts  2  were first positioned. Once the sealed edges are cut away, the sealing glass easily separates from each organic light-emitting part  2 . Thereafter, the sealed edges and pieces of cut sealing glass can be discarded or recycled. In this manner, the organic light-emitting parts can be readily obtained without using an additional separation process because the sealing glass  50  is not bonded to each organic light-emitting part  2 , but only to the edges of each region. The result of this manufacturing process is that one or more organic light-emitting devices  2  are produced, each having a super-thin glass substrate  1  which has a thickness of approximately 0.05 mm to approximately 0.5 mm. In  FIG. 5F , each piece represents the OLED shown in  FIG. 1 .  
         [0050]     Referring to  FIG. 6 , a sealing film  54  can be used instead of the sealing glass  50 . In this case, the same result as above is obtained. The sealing film  54  is formed of a material or materials that are insoluble and impermeable to the etching solution  53 .  
         [0051]     Referring to  FIG. 7 , the transparent glass  10  can be sealed with a resin material  55 . In this case, an additional process for removing the sealing resin material  55  after etching is required.  
         [0052]      FIG. 8  is a cross-sectional view of an OLED configured in accordance with another exemplary embodiment of the present invention. In this embodiment, the basic structure of the OLED of  FIG. 8  is the same structure of the OLED described with reference to  FIGS. 1, 2 ,  3  and  4 .  
         [0053]     The exemplary methods of manufacture described above can be applied to a frontal light emission OLED, that is, an OLED where the light is emitted toward the sealing part  3 . To strengthen a sealing part  3 , a circular polarized film  6  can be attached on an outer surface of the sealing part  3  to not only block external light from reaching the organic light-emitting devices, but also to give the sealing part  3  an increased predetermined strength. Alternatively, the strength of the sealing part  3  can be increased by attaching a glass substrate or film having a thickness of approximately 0.05 mm to approximately 0.3 mm to the sealing part  3 .  
         [0054]     In  FIG. 9 , an OLED configured in accordance with another exemplary embodiment of the present invention is depicted. This is a double-sided OLED formed by combining two OLEDs configured as described above.  
         [0055]     The OLED depicted in  FIG. 9  includes a first OLED  40  and a second OLED  40 ′. The first OLED  40  includes a display region  4  and a terminal region  8  having an organic light-emitting device formed on the glass substrate  1 . The display region  4  is sealed by a sealing part  3 . In this example, the display region  4  can be considered as a corresponding part to the organic light-emitting part  2  in  FIG. 1 , but is not limited thereto. The sealing part in this figure is identical to the sealing part  3  previously mentioned.  
         [0056]     The terminal region  8  is not sealed by the sealing part  3  but is exposed to the outside. As seen in  FIG. 9 , connecting parts  9  such as chip on glass (COG) or flexible printed circuit (FPC) for connecting the external electronic devices are connected to the terminal region  8 . The second OLED  40 ′ has the same structure as the first OLED  40 , therefore, a detailed description thereof will be omitted.  
         [0057]     The sealing parts  3  and  3 ′ of the first and the second OLEDs  40  and  40 ′ are bonded contacting each other so that the glass substrates  1  and  1 ′ face outward. The terminal regions  8  and  8 ′ are bonded to face in opposite directions. This bonding configuration of the terminal regions  8  and  8 ′ permits the later connection of external devices to the connecting parts  9  and  9 ′. In this manner, a super-thin, double-sided OLED can be constructed.  
         [0058]     When manufacturing the double sided OLED, the circular polarized films  6  and  6 ′, described above with reference to  FIG. 8 , can be applied on each external surface of the substrates  1  and  1 ′ (or sealing parts  3  and  3 ′) to block external light and increase the strength of is the substrate  1  and  1 ′ (or sealing parts  3  and  3 ′).  
         [0059]     As shown, described, and claimed herein, embodiments of the present invention permit a super-thin OLED to be manufactured to have a super-thin glass substrate that is not damaged during the manufacturing process. Moreover, adding a circularly polarized film to an outer surface of a sealing part increases the strength of a super thin OLED and blocks light from reaching and interfering with the organic light-emitting devices.  
         [0060]     While this invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled 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 as defined by the appended claims.

Technology Category: 4