Abstract:
The present invention relates to an encapsulation cap, an organic electroluminescent device having the same, and a manufacture method thereof. The encapsulation cap protects each of elements in a device formed on a substrate from outside, comprising a sealing surface adhering to the substrate , wherein at least one groove is formed at an edge of the sealing surface. The encapsulation cap protecting each of elements in a device formed on a substrate from outside comprises a sealant surface adhering to the substrate and a holding part holding each of elements of the device, wherein a concave part is formed on the sealant surface along an edge that the sealing surface and the holding part meet. The encapsulation cap, the organic electroluminescent device having the same, and the manufacturing method thereof according to the present invention can prevent overflowing of a sealant because of the structure capable of holding extra-sealant applied to the sealing surface.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     This application claims priority from Korean Patent Application Nos. 10-2005-0115456 filed on Nov. 30, 2005, and 10-2005-0114338 filed on Nov. 28, 2005, the contents of which are incorporated herein by reference in their entirety.  
       BACKGROUND OF THE INVENTION  
       [0002]     1. Field of the Invention  
         [0003]     The present invention relates to an encapsulation cap, an organic electroluminescent device having the same, and a manufacturing method thereof. Particularly, the present invention relates to the encapsulation cap capable of preventing defects like sealant overflowing.  
         [0004]     Also, the present invention relates to a mother glass substrate for manufacturing polyhedral encapsulation cap capable of forming a plurality of encapsulation caps having a structure capable of preventing defects like sealant overflowing on one substrate.  
       DESCRIPTION OF THE RELATED ART  
       [0005]     Organic electroluminescence is a phenomenon emitting a light having a predetermined wavelength by energy from exciton formed by recombination of an electron and a hole injected to an organic flow or high molecule) thin film through an anode and a cathode. And, an organic electroluminescent device is a display device using this light-emitting phenomenon.  
         [0006]     The organic electroluminescent device generally uses an encapsulation cap made of metal or glass.  
         [0007]      FIG. 1  is a sectional view showing the encapsulation structure of an organic electroluminescent device using the glass cap in the art.  
         [0008]     In  FIG. 1 , an emitting part  2  of the organic electroluminescent device  10  is formed on a certain area of a substrate  1 , and a glass cap  4  is bonded to the substrate  1  through a sealant  3  for separating the emitting part  2  from outer circumstance, that is, moisture or oxide.  
         [0009]     Also, the inside of the glass cap  4  is concaved to be able to form a getter  5 , that is, moisture absorbent.  
         [0010]     Then, for the emitting part  2  not to directly contact with the glass cap  4  and the getter  5 , a certain gap thicker than the emitting part  2  should be secured between the substrate  1  and the glass cap  4  oppositely disposed to each other. Therefore, a sealant  3  is generally manufactured by dispersing a spacer S in a liquid resin to maintain the gap between the substrate  1  and the glass cap  3 .  
         [0011]     But, when the spacer S is disposed between the substrate  1  and the glass cap  4 , the thickness of a contacting part of the substrate  1  and the glass cap  4  is increased, thereby causing a problem that outside moisture or oxide may be permeated into inside of the organic electroluminescent device  10  through the sealant  3 , and may erode the emitting part  2 .  
         [0012]     Also, in the process of distributing the sealant  3  onto the sealing surface of the encapsulation cap  4 , if the amount of sealant  3  is not controlled precisely, especially in case of exceeding a proper amount of sealant  3 , there may be a defect that the sealant  3  overflows inside or outside the sealing surface at the corner of the sealing surface bonded to the substrate  1  on which the encapsulation cap  4  and the emitting part  2  are formed.  
         [0013]     Therefore, it has been necessary to develop an encapsulation cap having the structure capable of solving the defect like sealant overflowing occurred at the corner of the sealing surface.  
         [0014]      FIG. 2  is a plan view showing a mother glass forming an organic electroluminescent device in the art.  
         [0015]     In  FIG. 2 , in the mother glass substrate  20  in which a plurality of organic electroluminescent devices  10  are formed, a gap (B area) between one organic electroluminescent device and another organic electroluminescent device  10  is very small. Thus, a large amount of sealant  3  exists between the organic electroluminescent devices  10  by the sealant  3  flowed to outside.  
         [0016]     Thus, the process of scribing each organic electroluminescent device  10  from the mother glass substrate  20  does not go smoothly.  
         [0017]     Therefore, there has been a need for an encapsulation cap having the constitution capable of cutting off the flow of sealant  3  to outer area.  
       SUMMARY OF THE INVENTION  
       [0018]     One object of the present invention is to provide an encapsulation cap, and an organic electroluminescent device having the same, which can prevent defects like overflowing of a sealant occurred at the corner of a sealing surface.  
         [0019]     Another object of the present invention is to provide an encapsulation cap, and an organic electroluminescent device having the same, which can encapsulate a sealant not having a spacer.  
         [0020]     Another object of the present invention is to provide a mother glass substrate for manufacturing polyhedral encapsulation cap on one glass substrate.  
         [0021]     Another object of the present invention is to provide an encapsulation cap, an organic electroluminescent device, and a manufacturing method thereof, having the structure in which a sealant does not affect function of the device by cutting off flowing of the sealant to outside.  
         [0022]     Another object of the present invention is to provide an encapsulation cap, an organic electroluminescent device, and a manufacturing method thereof, which can cut off flowing of a sealant without forming a wall on a substrate.  
         [0023]     The encapsulation cap according to one embodiment of the present invention comprises a sealing surface adhering to the substrate, wherein at least one groove is formed at an edge of the sealing surface.  
         [0024]     The organic electroluminescent device according to another embodiment of the present invention comprises a substrate; a first electrode formed on the substrate in a first direction; a second electrode formed in a second direction different from the first direction; an emitting area including an organic layer formed on an area that the first electrode and the second electrode cross; and an encapsulation cap bonded to the substrate by a sealant to encapsulate the emitting area. At least one groove is formed at an edge of a sealing surface of the encapsulation cap onto which the sealant is applied.  
         [0025]     The mother glass substrate for polyhedral encapsulation cap for manufacturing a plurality of encapsulation caps for encapsulating the organic electroluminescent device according to another embodiment of the present invention comprises a frame form of protrusion part defining a space for holding the emitting area of the organic electroluminescent device, wherein at least one first groove is formed on a top surface of the protrusion part, and a second groove is formed between adjacent protrusion parts.  
         [0026]     The encapsulation cap protecting elements formed on a substrate according to another embodiment of the present invention from outside comprises a sealant surface adhering to the substrate and a holding part holding each of elements of the device, wherein a concave part is formed on the sealant surface along by an edge meeting the sealing surface and the holding part.  
         [0027]     The organic electroluminescent device according to another embodiment of the present invention comprises a substrate; a first electrode formed on the substrate in a first direction; a second electrode formed in a second direction different from the first direction; an emitting area including an organic layer formed on an area that the first electrode and the second electrode cross; and an encapsulation cap bonded to the substrate by a sealant to encapsulate the emitting area. The encapsulation cap comprises a sealant surface adhering to the substrate and a holding part holding each of elements of the device, wherein a concave part is formed on the sealant surface along by an edge meeting the sealing surface and the holding part.  
         [0028]     The manufacturing method of the encapsulation cap according to another embodiment of the present invention comprises forming a sealant-applied area by etching a glass substrate; and forming a device-encapsulating area by etching the glass substrate on which the sealant-applied area is formed.  
         [0029]     The encapsulation cap, organic electroluminescent device having the same, and manufacturing method thereof, according to the present invention can cut off permeation of moisture and oxide into the device because the sealing part is thin by bonding the substrate and the encapsulation cap with a sealant not including a spacer.  
         [0030]     The encapsulation cap, the organic electroluminescent device having the same, and manufacturing method thereof, according to the present invention can prevent overflowing of the sealant due to the structure capable of holding an extra amount of sealant applied to the sealing surface.  
         [0031]     The mother glass substrate for manufacturing polyhedral encapsulation cap according to the present invention can easily separate each of device after contacting the substrate formed a plurality of the emitting part as well as manufacture a plurality of the encapsulation cap from the one substrate. 
     
    
     BRIEF DESCRIPTION OF THE DRAWING  
       [0032]      FIG. 1  is a sectional view showing an encapsulation structure of an organic electroluminescent device using an encapsulation cap in the art;  
         [0033]      FIG. 2  is a plan view showing a mother glass forming an organic electroluminescent device in the art;  
         [0034]      FIG. 3A  is a sectional view showing the organic electroluminescent device according to one embodiment of the present invention;  
         [0035]      FIG. 3B  is a perspective view showing the structure of the encapsulation cap of  FIG. 3A ;  
         [0036]      FIG. 3C  and  FIG. 3D  are views showing another embodiment of the encapsulation cap of  FIG. 3A ;  
         [0037]      FIG. 4A  is a plan view of the mother glass substrate for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention;  
         [0038]      FIG. 4B  is a partial plan view cutting the mother glass substrate for manufacturing the encapsulation cap of  FIG. 4A  along line A-A;  
         [0039]      FIG. 5  is a sectional view schematically showing the organic electroluninescent device according to another embodiment of the present invention;  
         [0040]      FIG. 6  is a sectional view showing the organic electroluminescent pixel of  FIG. 5 ;  
         [0041]      FIG. 7A  to  FIG. 7H  are sectional views showing the manufacturing process of the encapsulation cap of  FIG. 5 . 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0042]     The present invention will be more clearly understood from the detailed description in conjunction with the following drawings.  
         [0043]      FIG. 3A  is a sectional view showing the organic electroluminescent device according to one embodiment of the present invention. Only, the organic electroluminescent device of the embodiment is of a passive type.  
         [0044]     In  FIG. 3A , the organic electroluminescent device according to a first embodiment of the present invention includes a glass substrate  100 , and indium tin oxide or anode electrode layer  110  of metal formed by sputtering is formed on the substrate  100 .  
         [0045]     An insulation layer  120  formed by applying an insulation material, for example polyimide, is disposed on the top of the anode electrode layer  110 .  
         [0046]     A wall  130  crossing over the anode electrode layer  110  is formed on the top of the insulation layer  120 . The wall plays a role to separate a cathode electrode layer  150  as described below.  
         [0047]     On the top of the anode electrode layer  110  and the wall  130 , an organic layer  140 , for example, consisting of electron injecting layer, electron transmitting layer, emitting layer, hole transmitting layer, and hole injecting layer, is formed.  
         [0048]     The cathode electrode layer  150  crossing over the anode electrode layer  110  is formed on the top of the organic layer  140 .  
         [0049]     The cathode electrode layer  150  is preferably formed of a material having low work function, for example, high reactivity alloy based on alkali metals and alkaline earth metals. But, these reactivity metals cause a problem to worsen the device characteristic or reduce life of the device because they are easily oxidized by reacting with oxide or moisture.  
         [0050]     Also, the organic layer  140  formed at the bottom of the cathode electrode layer  150  is easily burned by oxide and moisture.  
         [0051]     Therefore, the organic electroluminescent device according to the present invention forms a protective layer by using the encapsulation cap  160  made of glass material, and the encapsulation cap  160  is bonded by the sealant  170  disposed in between the anode electrode layer  110 . The organic electroluminescent device according to the present invention need not disperse a spacer into the sealant  170  because of the structural characteristic of the encapsulation cap  160  as described below. Thus, it should be noted that the sealant  170  can be applied thinly.  
         [0052]     The encapsulation cap  160  according to an embodiment of the present invention may comprise a laminating body including the anode electrode layer  110 , the organic layer  140 , and the cathode electrode layer  150 , formed on the substrate  100  between inside of the encapsulation cap  160  and the substrate  100 , that is, a protruded form of protrusion part P from inside the encapsulation cap  160  so as to secure a space for holding the emitting part of the organic electroluminescent device.  
         [0053]     In one embodiment of the present invention, the protrusion part P of the encapsulation cap  160  can perform same function as the spacer because it is formed to a height capable of forming a certain gap enough for the emitting part to be disposed between the substrate  100  and inside of the encapsulation cap  160 . Thus, the organic electroluminescent device according to the present invention is advantageous in that it need not use a spacer in the sealant  170 .  
         [0054]     The encapsulation cap  160  according to one embodiment of the present invention can be formed by selectively removing soda-lime or non-alkali of glass substrate with using wet etching or sand blast method. That is, the protrusion part P can be formed by removing the other area of the glass substrate except for an area in which the protrusion part P is formed by a certain thickness. The removed depth of the glass substrate is the same as the height of the protrusion part P. Here, it is desirable that the height from inside of the encapsulation cap to the top of the protrusion part P is between 10 μm and 300 μm.  
         [0055]     It is preferable to form the encapsulation cap  160  by partially removing the glass substrate by wet etching method. When the glass substrate is etched by wet etching method, the edge of the top surface of the protrusion part P of the encapsulation cap  160  is smoothly rounded.  
         [0056]     Also, in the edge of the top part of the protrusion part P of the encapsulation cap  160  according to one embodiment of the present invention, a groove capable of holding extra-sealant at the time of bonding to the substrate  100  is formed. Hereinafter, this will be described with reference to the drawings.  
         [0057]      FIG. 3B  is a perspective view showing the structure of the encapsulation cap of  FIG. 3A . And,  FIG. 3C  and  FIG. 3D  are views showing another embodiment of the encapsulation cap of  FIG. 3A .  
         [0058]     In  FIG. 3B , an oblique line of groove  180  is formed in each edge of top surface of the protrusion part P defining a space A capable of holding the emitting part.  
         [0059]     The groove  180  secures enough space for holding extra-sealant when more sealant  170  than the margin of error is dispensed on the sealing surface of the encapsulation cap  160 , that is, the top surface of the protrusion part P in the present embodiment.  
         [0060]     Thus, in case of compressing the encapsulation cap  160  and the substrate on which the organic electroluminescent part is formed, when the sealant  170  is applied, there is no such problem that extra-sealant is flown in or out of the sealing surface.  
         [0061]     The width and depth of the groove  180  are determined according to a number of process conditions, such as size of the organic electroluminescent device manufactured, width and depth of the protrusion part P of the encapsulation cap  160 , applied force at the time of compressing the substrate  100  and the encapsulation cap  160  after applying the sealant  170 , etc. These process conditions may be decided by a person skilled in the art without much difficulty.  
         [0062]     More detail, for preventing the sealant  170  is flown out of the sealing surface when the substrate  100  and the encapsulation cap  160  compress, it is preferable that the extra-sealant is hold into the groove  180  well. Preferably, for holding the sealant  170  into the groove  180  well at the time of compressing the substrate  100  and the encapsulation cap  160 , the groove  180  is formed to have 100 μm or more of depth.  
         [0063]     Also, it is preferable that the groove  180  has same depth as the space A for holding the emitting part. In case the depths of the groove  180  and the space A are same, the protrusion part P and the groove  180  can be formed by one time etching process in the formation process of the encapsulation cap  160 , as explained below.  
         [0064]     Also, the form of the groove  180  is not limited as long as it is structured enough to hold extra-sealant. That is, it is fine to form the oblique line of groove  180  as pairs in each edge of the protrusion part P as shown in  FIG. 3C , or to form a round groove  180  in each edge of the protrusion part P as shown in  FIG. 3D .  
         [0065]     The desirable form of the groove  180  is of oblique line. In case of compressing the encapsulation cap  160  and the substrate after the sealant  170  is applied thereto, the sealant  170  is flown out of the sealing surface mostly at the edge area. In this case, it is an oblique line of the groove  180  that can best hold the sealant  170  flowing to outside from the sealing surface, without obstructing the flow of the sealant  170 .  
         [0066]     It is desirable to use wet etching method as the method of forming the groove  180  at the edge of the protrusion part P of the encapsulation cap  160 . Also, the encapsulation cap  160  having a frame form of protrusion part P including the groove  180  at the edge can be manufactured through single etching process by simultaneously etching a part of the glass substrate on which the groove  180  is formed, At the time of forming the protrusion part P by partially removing a part of the glass substrate by using wet etching method.  
         [0067]     This will be described in detail.  
         [0068]     First, the other part except an area on which the frame form of protrusion part P is formed (except the area on which the groove  180  is formed) is exposed by masking-treating the glass substrate prepared separately as resist. In the case, a part on which the groove  180  is formed is also exposed.  
         [0069]     Next, the exposed part of the substrate is removed by a predetermined depth by soaking the masking-treated glass substrate in etching liquid for a certain period of time.  
         [0070]     Finally, the etched glass substrate is washed well with a washing liquid like pure water, and then the resist remaining on the surface of the substrate is removed, to obtain a completed encapsulation cap  160 .  
         [0071]     Hereinafter, a preferable embodiment for the structure of the mother glass substrate for manufacturing a polyhedral encapsulation cap  160  capable of forming a plurality of encapsulation caps  160  from one substrate, and the manufacturing method thereof according to one embodiment of the present invention will be described.  
         [0072]      FIG. 4A  is a plan view of the mother glass substrate for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention. And,  FIG. 4B  is a partial plan view of the mother glass substrate for manufacturing the encapsulation cap of  FIG. 4A  cut by line A-A.  
         [0073]     In  FIG. 4A  and  FIG. 4B , the mother glass substrate for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention includes a plurality of frame form of protrusion parts  210  disposed on a glass substrate  200  in the form of lattice, and a plurality of concave parts  220  defined by the protrusion parts  210 . One protrusion part  210  and one concave part  220  define the encapsulation cap  250  for encapsulating the organic electroluminescent device. The present embodiment exemplifies a case of forming 3×4 of encapsulation cap  250  on one glass substrate  200 .  
         [0074]     The top surface of the protrusion part  210  corresponds to the sealing surface on which the sealant is applied for bonding to the substrate (not shown) on which the organic electroluminescent part is formed.  
         [0075]     The protrusion part  210  can perform the same function as the spacer because the concave part  220  is modified to a height capable of forming a space enough for holding the organic electroluminescent part formed on a separate substrate. Therefore, all the encapsulation caps  250  separated from the mother glass substrate according to the present invention is suitable for bonding to the substrate on which the organic electroluminescent part is formed, only with the sealant not including the spacer.  
         [0076]     Also, an oblique line of groove  240  is formed at an edge of the protrusion part  210 . In the encapsulating process of the organic electroluminescent device, the groove  240  functions to secure enough space for holding extra-sealant when a sealant more than the margin of error is dispensed on the top surface of the protrusion part  210 .  
         [0077]     The form and function of the groove  240  are same as the encapsulation cap  160  according to one embodiment of the present invention shown in  FIG. 3B ,  FIG. 3C  and  FIG. 3D , and so will not be explained further.  
         [0078]     The protrusion part  210  is formed to a height capable of forming the concave part  220  suitable for holding the organic electroluminescent device. The height T 1  from the bottom surface of the concave part  220  to the top surface of the protrusion part  210  is, for example, 10 μm to 300 μm Also, the total thickness T 2  of the substrate  200  including the protrusion part  210  is, for example, 0.63 mm to 0.7 mm.  
         [0079]     Also, another groove  230  is disposed between the protrusion parts  210 ,  210  of adjacent encapsulation caps  250 ,  250 . The groove  230  is useful in the subsequent process of separating a plurality of encapsulation caps  250  formed on the glass substrate  200  separately from each other. That is, if scribing and force are applied along the groove  230  formed between the adjacent encapsulation caps  250 ,  250 , the encapsulation caps  250  are separated to individual ones easily because stress is concentrated on the part on which the groove  230  is formed.  
         [0080]     The above is also applicable when separating the encapsulation caps  250  by individual devices (cells) after arranging the substrate on which a plurality of emitting parts of the organic electroluminescent device are formed, and the mother glass substrate of the present invention, and bonding them by applying a sealant.  
         [0081]     It is desirable that the depth T 3  from the top surface of the protrusion part  210  to the bottom of the groove  230  is the same as the height T 1  of the protrusion part  210 , but it is not necessary.  
         [0082]     The mother glass for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention can be manufactured by using wet etching method, sand blast method, or press method. Preferably, the mother glass for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention is manufactured by wet etching method or sand blast method. More preferably, it is manufactured by wet etching method.  
         [0083]     The manufacturing method of the mother glass for manufacturing polyhedral encapsulation cap according to one embodiment of the present invention by the wet etching method is as follows.  
         [0084]     First, the glass substrate  200  having a size capable of forming 3×4 of encapsulation cap  250  is prepared. In this case, soda-lime or non-alkali of glass substrate can be used as the glass substrate  200 .  
         [0085]     Next, a resist is formed on the front surface of the substrate  200 , and by patterning the formed resist, the other part of the glass substrate except an area on which the protrusion part P is formed (except the area on which the groove  240  is formed) is exposed. At this time, the part on which the groove  240  is formed is also exposed. This is called as masking-treatment of the glass substrate  200 .  
         [0086]     Then, the exposed part of the glass substrate  200  is removed by a predetermined depth by soaking the masking-treated glass substrate  200  in etching liquid for a certain period of time. Here, the soaking time of the glass substrate  200  in etching liquid may be varied depending on some factors, for example, quality of the glass substrate  200 , type of etching liquid, and quantity removed from the glass substrate  200 . But, a person skilled in the art can properly select them.  
         [0087]     Finally, the resist remaining on the top of the protrusion part  210  is removed after the etched glass substrate  200  is washed well with washing liquid like pure water.  
         [0088]     In case of using the wet etching method as shown above, the glass substrate  200  can be removed by uniform depth from desired parts, that is, an area on which the concave part  220  and the groove  230  are formed. Also, the edge of the top surface of the protrusion part  210  can be smoothly rounded.  
         [0089]     Hereinafter, the encapsulation cap of an active type of organic electroluminescent device according to another embodiment of the present invention will be described in detail.  
         [0090]      FIG. 5  is a sectional view schematically showing the organic electroluminescent device according to another embodiment of the present invention. And,  FIG. 6  is a sectional view showing the organic electroluminescent pixel of  FIG. 5 .  
         [0091]     In  FIG. 5 , the organic electroluminescent device  300  according to the present invention includes an active area  350  formed on a substrate  400 , a circuit part  320 , a circuit wiring part  310 , an encapsulation cap  330 , and a sealant  340 .  
         [0092]     The active area  350  consists of a plurality of organic electroluminescent pixels, and is an emitting area.  
         [0093]     In detail, in  FIG. 6 , the pixel is an active matrix-type of device, and includes driving transistors  410 A and  410 B, capacitors  420 A and  420 B, connecting contacted holes  430 A and  430 B, anode electrode layers  480 A and  480 B, insulation layers  490 A and  490 B, organic layers  500 A and  500 B, and cathode electrode layer  510 .  
         [0094]     The driving transistors  410 A and  410 B are driving devices driving the pixel, particularly a diode, and each are connected to the anode electrode layers  480 A and  480 B through the connecting contacted holes  430 A and  430 B. For example, a first driving transistor  410 A is connected to a first anode electrode layer  480 A through a first connecting contacted hole  430 A, and a second driving transistor  410 B is connected to a second anode electrode layer  480 B through a second connecting contacted hole  430 B.  
         [0095]     Also, the driving transistors  410 A and  410 B each are connected to the capacitors  420 A and  420 B. That is, the first driving transistor  410 A is connected to a first capacitor  420 A, and the second driving transistor  410 B is connected to a second capacitor  420 B.  
         [0096]     Each of the capacitors  420 A and  420 B consist of a capacitor electrode, a voltage opening electrode, and a first insulation layer disposed between the capacitor electrode and the voltage opening electrode.  
         [0097]     The connecting contact holes  430 A and  430 B are connected to each drain of the driving transistors  410 A and  410 B, consist of metal, and provide a positive voltage applied through the driving transistors  410 A and  410 B to the anode electrode layers  480 A and  480 B.  
         [0098]     The anode electrode layers  480 A and  480 B provide holes to the organic layers  500 A and  500 B according to the provided positive voltage. The insulation layers  490 A and  490 B are formed between the anode electrode layers  480 A and  480 B to block electrical connection between the anode electrode layers  480 A and  480 B. Only, the insulation layers  490 A and  490 B partially cover the top surface of the anode electrode layers  480 A and  480 B.  
         [0099]     The organic layers  500 A and  500 B are formed on the anode electrode layers  480 A and  480 B, and include Hole Injection Layer HILL, Hole Transporting Layer HTL, Emitting Layer EL, Electron Transporting Layer ETL and Electron Injection Layer EIL. When a positive voltage is applied to the anode electrode layers  480 A and  480 B, and a negative voltage is applied to the cathode electrode layer  510 , the organic layers  500 A and  500 B generate a light having a certain wavelength.  
         [0100]     The cathode electrode layers  510  are formed on the organic layers  500 A and  500 B.  
         [0101]     The circuit part  320  inputs a signal into the transistor of the pixel, and is connected to the circuit wiring part  310 .  
         [0102]     The circuit wiring part  310  plays a role to supply driving power to the pixels.  
         [0103]     The encapsulation cap  330  encapsulates all areas, that is, the active area  350 , the circuit part  320 , and the circuit wiring part  310 , except the pad part (not shown).  
         [0104]     The encapsulation cap  330  includes a sealing surface adhering to the substrate  400 , and a holding part D holding each of elements of the device. On the sealant surface, a concave part  332  is formed along an edge that the sealing surface and the holding part D meet.  
         [0105]     The concave part  332  functions to secure enough space for holding extra-sealant when a sealant  340  more than the margin of error is dispensed on the sealing surface of the encapsulation cap  330 .  
         [0106]     When the encapsulation cap  330  and the substrate  400  having the active area D formed thereon compress each other after the sealant  340  is dispersed thereto, extra-sealant  340  is formed inside the sealing surface, that is, the concave part  332 , than outside the sealing surface. Thus, the flowing of the sealant  340  to outside of the sealing surface may be prevented.  
         [0107]     The width and depth of the concave part  332  are determined according to a number of process conditions, such as size of the organic electroluminescent device manufactured, applied force at the time of compressing the substrate  400  and the encapsulation cap  330  after applying the sealant  340 , etc. These process conditions may be decided by a person skilled in the art without much difficulty.  
         [0108]     The width of the concave part  332  is 30% or less of the total width of the sealing surface.  
         [0109]     If the width of the concave part  332  is more than 30%, the sealant  340  may be applied to the concave part  332  itself, and flowed into the holding part D, not that extra sealant flows into the concave part  332  at the time of compressing the encapsulation cap  330  and the substrate  400 .  
         [0110]     Also, the width of the concave part  332  is between 50 μm and 100 μm. If the width of the concave part  332  is more than 100 μm, the balance of the encapsulation cap  330  may be broken because the width of the sealing surface contacting with the substrate  400  in between the sealant  340  becomes relatively small. Preferably, the width of the concave part  332  is in the range of 50 μm and 55 μm.  
         [0111]     Hereinafter, the manufacturing process of the encapsulation cap  330  will be described in detail.  
         [0112]      FIG. 7A  to  FIG. 7H  are sectional views showing the manufacturing process of the encapsulation cap of  FIG. 5 .  
         [0113]     First, as shown in  FIG. 7A , a photoresist  610  is applied onto top of a glass substrate  600 , and then a first mask  620  on which a pattern is formed is disposed on the top of the photoresist  610 . The first mask  620  forms the pattern of a size corresponding to the sealant  340 -applied area of the substrate  400 .  
         [0114]     Subsequently, a light is shot onto the top of the first mask  620 . Accordingly, a part of the photoresist  610  exposed by the light is cured, and the other part not exposed by the light is not cured.  
         [0115]     Then, the photoresist pattern  612  is formed as shown in  FIG. 7B , by developing the exposed glass substrate  600  after removing the first mask  620 .  
         [0116]     Next, a first concave part  602  having a certain depth is formed by soaking the glass substrate  600  on which the pattern  612  is formed, in an etching solution for a certain period of time, as shown in  FIG. 7C . And, the photoresist pattern  612  is peeled off by developing the glass substrate  600  on which the first concave part  602  is formed, as shown in  FIG. 7D .  
         [0117]     And, the photoresist  610  is applied onto the glass substrate  600  on which the first concave part  602  is formed, and a second mask  630  is disposed on top of the photoresist  610  on which a pattern is formed, as shown in  FIG. 7E . The second mask  630  forms the pattern to a corresponding size to the device encapsulation area of the substrate  400 .  
         [0118]     Subsequently, a light is shot onto the top of the second mask  630 . Accordingly, a part of the photoresist  610  exposed by the light is cured, and the other part not exposed by the light is not cured.  
         [0119]     Then, a photoresist pattern  614  is formed by developing the exposed glass substrate  600  after removing the second mask  630 , as shown in  FIG. 7F .  
         [0120]     And, a second concave part  604  having a certain depth is formed by soaking the glass substrate  600  on which the pattern  614  is formed, in an etching solution for a certain period of time, as shown in  FIG. 7G . The second concave part  604  corresponds to the device encapsulation area.  
         [0121]     Then, the photoresist pattern  614  is peeled off by developing the glass substrate  600  on which the second concave part  604  is formed, as shown in  FIG. 7H , whereby the encapsulation cap  330  as shown above is formed.  
         [0122]     From the preferred embodiments for the present invention, it should be noted that modifications and variations can be made by a person skilled in the art in light of the above teachings. Therefore, it should be understood that changes may be made for a particular embodiment of the present invention within the scope and spirit of the present invention outlined by the appended claims.