Abstract:
A sealant disposed between two substrates to be sealed, the sealant comprising: at least two layers disposed layered on top of each other between the two substrates, wherein the at least two layers comprise materials having different components and at least one layer selected from the at least two layers includes a thermoplastic glass frit. A dye-sensitized solar cell including the sealant, and a method of manufacturing a dye-sensitized solar cell are also provided.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2009-0083157, filed on Sep. 3, 2009, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. 
       BACKGROUND OF THE INVENTION 
     Field of the Invention 
       [0002]    One or more embodiments of the present invention relate to a sealant for sealing an electrolyte solution included in a dye-sensitized solar cell, a dye-sensitized solar cell including the an electrolyte solution, and a method of manufacturing a dye-sensitized solar cell. 
       SUMMARY OF THE INVENTION 
       [0003]    Solar energy has been spotlighted as one of the renewable energy sources to replace energy obtained from oil, coal, and natural gas. According to their manufacturing materials, solar cells are classified into silicon solar cells and compound semiconductor solar cells. Single crystal silicon solar cells, poly crystal silicon solar cells, amorphous silicon solar cells, and the like have been commercialized. Single crystal silicon solar cells have an energy efficiency of about 18%, poly crystal silicon solar cells have an energy efficiency of about 15%, and amorphous silicon solar cells have an energy efficiency of about 10%. Silicon solar cells are formed of a semiconductor material and generate electricity by opto-electric conversion. 
         [0004]    Meanwhile, dye-sensitized solar cells generate electricity by photosynthesis according to a photo-electrochemical conversion mechanism. Dye-sensitized solar cells have an energy conversion efficiency higher than about 11%. Dye-sensitized solar cells have a theoretical conversion efficiency higher than silicon solar cells, which increases the actual energy conversion efficiency and reduces the manufacturing costs thereof to ⅕. Thus, dye-sensitized solar cells can be used in a wide range of applications. 
         [0005]    When dye-sensitized solar cells absorb sunlight, electrons are transported in dye molecules, and are injected into a conduction band of a semiconductor oxide. Then, the injected electrons pass through interfaces between particles of an oxide electrode and reach a conductive film. Thereafter, holes generated in the dye molecules are filled with electrons supplied by an electrolyte placed between two substrates sealed with a sealant, thereby generating a current. 
       SUMMARY 
       [0006]    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. 
         [0007]    According to one or more embodiments of the present invention, a sealant is disposed between two substrates to be sealed, the sealant including: at least two layers disposed layered on top of each other between two substrates, wherein the at least two layers each include materials having different components, and at least one of the at least two layers includes a thermoplastic glass frit. 
         [0008]    In one embodiment, one of the at least two sealing layers fills a major portion of the space between the two substrates, and a laser sealing operation is performed on another sealing layer, or another sealing layer is formed of an organic-based resin material. This can reduce problems that occur when the laser sealing operation is performed on a single sealant layer, or a single sealant layer is formed of an organic-based resin material. 
         [0009]    Each of the at least two layers may include a thermoplastic glass frit and one of the at least two layers may further include a laser absorption material. 
         [0010]    A laser sealing operation may be performed on one of the at least two sealing layers, thereby obtaining a sealant having high sealing quality and having uniform thickness, compared to the case where a single sealant layer has a laser sealing operation performed on it. 
         [0011]    One of the at least two layers may include a thermoplastic glass frit and another layer may comprise an organic-based resin material. 
         [0012]    When one of the at least two layers is formed of an organic-based resin material, this thereby prevents an electrolyte component from diffusing or being transmitted and being discharged externally, compared to the case where a single sealant layer is formed of an organic-based resin material. 
         [0013]    When one of the at least two layers does not include a laser absorption material and is a first sealing layer, and another layer includes a laser absorption material and is a second sealing layer, one of the at least two layers including a thermoplastic glass frit may be the first sealing layer, and another layer including an organic-based resin material may be the second sealing layer, the thickness of the first sealing layer may be greater than or equal to the thickness of the second sealing layer. 
         [0014]    One of the at least two layers including a thermoplastic glass frit may be the first sealing layer, and another layer including an organic-based resin material may be the second sealing layer, the thickness of the first sealing layer may be greater than or equal to a thickness of the second sealing layer. 
         [0015]    The thickness of a layer on which a laser sealing operation is performed, or a layer including an organic-based resin material, is reduced as much as possible, thereby obtaining a sealant having uniform thickness, and achieving excellent quality of sealing. 
         [0016]    The laser absorption material may include one selected from the group consisting of manganese (Mn), iron (Fe), vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), copper (Cu), and combinations thereof. The organic-based resin material may include one selected from the group consisting of an epoxy resin material, an acrylic resin material, an olefin-acrylic based resin material, an olefin-acrylic-ion based resin material, an olefin-based resin material, and combinations thereof. 
         [0017]    According to one or more embodiments of the present invention, a dye-sensitized solar cell includes: a first substrate and a second substrate disposed to face each other; a first electrode and a second electrode formed on the inner surfaces of the first substrate and the second substrate, respectively, that face each other; an electrolyte solution filled between the first substrate and the second substrate; and a sealant disposed on the periphery of inner surfaces of the first substrate and the second substrate to seal the electrolyte solution, and comprising a first sealing layer and a second sealing layer, and the first sealing layer contacting the inner surface of the first substrate and the second sealing layer contacting the inner surface of the second substrate, wherein the first electrode comprises a semiconductor oxide layer onto which a plurality of dye molecules are adsorbed, at least one of the first sealing layer or the second sealing layer including a thermoplastic glass frit, and the first sealing layer and the second sealing layer comprise materials having different components. 
         [0018]    The first sealing layer and the second sealing layer may include a thermoplastic glass frit, and the second sealing layer may further include a laser absorption material. 
         [0019]    The first sealing may include a thermoplastic glass frit, and the second sealing layer may include an organic-based resin material. 
         [0020]    A thickness of the first sealing layer may be between about 50 μm and about 150 μm and a thickness of the second sealing layer may be between about 3 μm and about 50 μm. 
         [0021]    According to one or more embodiments of the present invention, a method of manufacturing a dye-sensitized solar cell, the method including: forming a first electrode on a first substrate; forming a second electrode on a second substrate facing the first substrate; forming a first sealing layer on an inner surface of the first substrate or the second substrate; forming a second sealing layer on an inner surface of the first sealing layer or on a region of the second substrate corresponding to the first sealing layer; aligning and sealing the first substrate and the second substrate; and injecting an electrolyte solution between the first substrate and the second substrate, wherein the first sealing layer and the second sealing layer comprise materials having different components, and at least the first sealing layer comprises a thermoplastic glass frit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0022]    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 of which: 
           [0023]      FIG. 1  is a diagram illustrating the operation of a dye-sensitized solar cell according to an embodiment of the present invention; 
           [0024]      FIG. 2  is a schematic cross-sectional view of a dye-sensitized solar cell sealed by a sealant according to an embodiment of the present invention; 
           [0025]      FIG. 3  is a flowchart illustrating a method of manufacturing a dye-sensitized solar cell according to an embodiment of the present invention; 
           [0026]      FIGS. 4A through 4E  are diagrams illustrating a method of forming a sealant according to an embodiment of the present invention; and 
           [0027]      FIGS. 5A through 5E  are diagrams illustrating a method of forming a sealant according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, 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 referring to the figures, to explain aspects of the present description. 
         [0029]      FIG. 1  is a diagram showing the operation of a dye-sensitized solar cell according to an embodiment of the present invention. Referring to  FIG. 1 , when sunlight is incident onto the dye-sensitized solar cell, dye molecules  114  adsorbed on the surface of a semiconductor oxide layer  113  transit from a highest occupied molecular orbital (HOMO) energy level to a lowest unoccupied molecular orbital (LUMO) energy level and thus electrons are generated. That is, a pair of electron and hole of the dye molecules  114  are separated from each other so that electrons and holes are generated, the electrons are discharged, and the dye molecules  114  are oxidized. The electrons are injected into the conduction band of the semiconductor oxide layer  113  and pass through interfaces between particles of the semiconductor oxide layer  113  to reach a conductive film  111  according to a chemical diffusion gradient. Meanwhile, holes generated at the HOMO energy level of the dye molecules  114  are filled with electrons received from iodine ions 3I −  in an electrolyte  115 . The iodine ions 3I −  provide the holes with the electrons and are oxidized. The iodine ions 3I −  oxidized in the electrolyte  115  are reduced by electrons received from an opposite electrode  101  through an external electrical circuit. Thus, when the dye-sensitized solar cell absorbs sunlight, electrons circulate therein so that a current flows in the dye-sensitized solar cell. 
         [0030]      FIG. 2  is a schematic cross-sectional view of a dye-sensitized solar cell including a sealant  130  according to an embodiment of the present invention. 
         [0031]    The sealant  130  will now be described in conjunction with the whole structure of the dye-sensitized solar cell. Referring to  FIG. 2 , the dye-sensitized solar cell includes a first substrate  110 , a second substrate  100 , a first electrode  210 , a second electrode  200 , an electrolyte solution  115 , and the sealant  130 . 
         [0032]    The first electrode  210  is formed on the first substrate  110  and may be a photocathode electrode that serves as a cathode. The second electrode  200  is formed on the second substrate  100  and may be an opposite electrode that serves as an anode. The first substrate  110  and the second substrate  100  are transparent. The electrolyte solution  115  is filled between the photocathode electrode  210  and the opposite electrode  200 . The first substrate  110  and the second substrate  100  are sealed with the sealant  130  to prevent the electrolyte solution  115  from leaking. 
         [0033]    The photocathode electrode  210  may include a first transparent conductive layer  111  formed on the first substrate  110 , a plurality of first grid electrodes  112  formed on the first transparent conductive layer  111 , a protection film  160  covering the first grid electrodes  112 , a nano-sized semiconductor oxide layer  113 , and a plurality of dye molecules  114  adsorbed onto the nano-sized semiconductor oxide layer  113 . 
         [0034]    The first substrate  110  may be formed of a transparent glass material or a flexible plastic material, such as polyethylene terephthalate (PET), polycarbonate (PC), polyimide (PI), polyethylene naphthalate (PEN), or polyethersulfone (PES). 
         [0035]    The first transparent conductive layer  111  may be a conductive thin film such as indium tin oxide (ITO) or F doped tin dioxide (SnO 2 ) (FTO). The first transparent conductive layer  111  may have a single layer structure or a multiple layer structure. The conductive thin film is used to increase the efficiency of forming electrons. The first transparent conductive layer  111  has a high permeability, which facilitates sunlight to reach the dye molecules  114 . Meanwhile, the first transparent conductive layer  111  has a relatively low electrical conductivity, which reduces the efficiency of forming electrons. Thus, the first grid electrodes  112  may be formed in order to compensate for the low electrical conductivity of the first transparent conductive layer  111 . 
         [0036]    The first grid electrodes  112  are formed of metal, such as silver (Ag) and aluminum (Al), and may be formed in a variety of patterns, such as a stripe pattern or a grid pattern. The first grid electrodes  112  have an electrical resistance lower than the first transparent conductive layer  111  so that a current smoothly flows therethrough. The first grid electrodes  112  may be covered by the protection film  160  for protection against the electrolyte solution  115 . 
         [0037]    The nano-sized semiconductor oxide layer  113  is formed on the first transparent conductive layer  111  and the protection film  160 . The nano-sized semiconductor oxide layer  113  may be a titanium dioxide (TiO 2 ) layer, a tin dioxide (SnO 2 ) layer, or a zinc oxide (ZnO) layer. The nano-sized semiconductor oxide layer  113  has a structure in which a plurality of nanometer sized wide band gap semiconductor particles are stacked at an appropriate interval from each other. The dye molecules  114  containing, for example, a Ru complex compound, are chemically adsorbed onto the surfaces of the nanometer sized wide band gap semiconductor particles. When the surface area of the nanometer sized wide band gap semiconductor particles onto which the dye molecules  114  are adsorbed is larger, more current may be generated. 
         [0038]    The dye molecules  114  may contain, for example, the Ru complex compound. Thiophene, phthalocyanine, porphyrin, indoline or quinoline and an organic substance containing derivatives thereof may be used as the dye molecules  114 . 
         [0039]    The opposite electrode  200  may include a second transparent conductive layer  101  formed on the second substrate  100 , a plurality of second grid electrodes  102  formed on the second transparent conductive layer  101 , the protection film  160  covering the second grid electrodes  102 , and a catalyst film  103 . 
         [0040]    The second substrate  100  may be formed of a transparent glass material or a flexible plastic material. 
         [0041]    The second transparent conductive layer  101  may be a conductive thin film such as ITO or FTO. The second grid electrodes  102  may be formed in order to compensate for the low electrical conductivity of the second transparent conductive layer  101 . The protection film  160  may be formed on the second grid electrodes  102  to protect the second grid electrodes  102  from the electrolyte solution  115 . 
         [0042]    The catalyst film  103  may be formed on the second transparent conductive layer  101  and the protection film  160 . The catalyst film  103  is, for example, a platinum (Pt) or carbon (C) thin film. The catalyst film  103  acts as a reduction catalyst that receives electrons through an external circuit. The platinum thin film is formed and thus the catalyst film  103  reflects sunlight incident through the photocathode electrode  210 , thereby increasing the conversion efficiency of solar energy. 
         [0043]    The electrolyte solution  115  is disposed between the photocathode electrode  210  and the opposite electrode  200 . The electrolyte solution  115  is, for example, an iodine oxidation-reduction liquid electrolyte solution (I 3   − /3I − ). The electrolyte solution  115  reduces the oxidized dye molecules  114 . That is, the electrolyte solution  115  offers electrons to the oxidized dye molecules  114 . 
         [0044]    The present invention is not limited to the first electrode  210  and the second electrode  200  and it would be understood by one of ordinary skill in the art that various modifications may be possible. For example, the first electrode  210  and the second electrode  200  may not include grid electrodes, or the first electrode  210  and the second electrode  200  may not include the first and second transparent conductive layers  101  and  111 . Alternatively, the first electrode  210  and the second electrode  200  may also not include the protection film  160 . 
         [0045]    The sealant  130  is used to prevent the electrolyte solution  115  from leaking from the area between the first substrate  110  and the second substrate  100 . The sealant  130  is placed in internal peripheries of the first substrate  110  and the second substrate  100 . The sealant  130  of the present embodiment is layered in the direction in which the first substrate  110  and the second substrate  100  are stacked. The sealant  130  may have a two-layer structure including a first sealing layer  131  and a second sealing layer  132  that are layered on top of each other. However, the present invention is not limited to the two-layer structure and the sealant  130  may have a three-layer structure. 
         [0046]    Due to the two-layer structure or three-layer structure, the sealant  130  can have high sealing quality, and be thick with uniform thickness. In more detail, the dye-sensitized solar cell includes the photocathode electrode  210 , the opposite electrode  200 , and the electrolyte solution  115  between the first substrate  110  and the second substrate  100  wherein the first substrate  110  and the second substrate  100  are spaced apart from each other by a distance generally larger than 60 μm. Since the sealant  130  of the dye-sensitized solar cell maintains a gap between the first substrate  110  and the second substrate  100 , the sealant  130  is necessarily thick, having a thickness larger than 60 μm. However, it is difficult to obtain a thick layer having uniform thickness. Also, when a thick layer is irradiated by a laser beam, plastic deformation occurs, which makes it difficult to obtain a uniform and high quality sealant. Also, when an organic-based sealing material is used instead of a thermoplastic glass frit, since the electrolyte solution  115  is likely lost through the organic-based film, the sealant  130  must be thin. 
         [0047]    In view of the above, the sealant  130  having a two-layer structure is used in the present embodiment. In this case, a first sealing layer  131  is formed on any one of the first substrate  110  or the second substrate  100  to have a thickness smaller than the distance between the first substrate  110  and the second substrate  100 . A second sealing layer  132  is formed on the other one of the first substrate  110  and the second substrate  100  to have a thickness equal to a difference between the distance between the first substrate  110  and the second substrate  100  and the thickness of the first sealing layer. The first sealing layer  131  includes a thermoplastic glass frit obtained by annealing a frit paste including a glass frit. The second sealing layer  132  may be a laser sealing layer or an organic-based sealing layer including an organic-based sealant. Since the first sealing layer  131  is separately disposed from the second sealing layer  132 , the thickness of the second sealing layer  132 , which is subject to plastic deformation due to the laser beam, or leak of the electrolyte solution through the organic-based film, is smaller than the gap between the first substrate  110  and the second substrate  100 , thereby overcoming the problems associated with the sealant  130  being a single thick layer. 
         [0048]    The first sealing layer  131  of the sealant  130  includes a thermoplastic glass frit, and the second sealing layer  132  thereof includes a thermoplastic glass frit and a laser absorption material. A wavelength of a laser beam used to perform a laser sealing operation may be in an infrared region, for example, between 808 nm and 1,064 nm. The laser absorption material may include manganese (Mn), iron (Fe), vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), or copper (Cu). However, the present invention is not limited thereto and the laser absorption material may be a high optical absorption material with respect to the wavelength of laser. 
         [0049]    The thickness of the first sealing layer  131  may be equal to or greater than that of the second sealing layer  132 . For example, the thickness of the first sealing layer  131  may be 60 μm, and the thickness of the second sealing layer  132  may be 40 μm. The first sealing layer  131  occupies a major portion of the gap between the first substrate  110  and the second substrate  100  so that the second sealing layer  132  on which the laser sealing operation is performed may be thin, thereby reducing plastic deformation, obtaining an overall thick sealant having uniform thickness, and achieving excellent quality of sealing when a laser sealing operation is performed. If the sealant  130  is formed of an inorganic material, the sealant  130  is water-proof, thereby preventing the electrolyte solution  115  from leaking. 
         [0050]    According to a sealant  230  of another embodiment, a first sealing layer  131  includes a thermoplastic glass frit, and a second sealing layer  132  includes an organic-based resin material. The organic-based resin material may be, for example, an epoxy resin material, an acrylic resin material, an olefin-acrylic based resin material, an olefin-acrylic-ion based resin material, or an olefin-based resin material. The first sealing layer  131  occupies a major portion of the gap between the first substrate  110  and the second substrate  100  so that the second sealing layer  132  formed of the organic-based resin material may be thin. Accordingly, the sealant  230  is thick and has uniform thickness, and thus high quality sealing can be achieved. A sealing operation is performed at a relatively low temperature below 150° C. by using an organic-based sealing material, thereby reducing thermal damage of the dye and increasing durability against external shock since the organic-based sealing material has higher elasticity than an inorganic-based sealing material. 
         [0051]    A method of manufacturing a dye-sensitized solar cell including a sealant  130  or a sealant  230  will now be described.  FIG. 3  is a flowchart illustrating a method of manufacturing a dye-sensitized solar cell according to an embodiment of the present invention. 
         [0052]    Referring to  FIG. 3 , the method of manufacturing a dye-sensitized solar cell includes forming the photocathode electrode  210  on the first substrate  110  (S 100  through S 150 ), forming the opposite electrode  200  on the second substrate  100  (S 101  through S 141 ), sealing and combining the first substrate  110  with the second substrate  100  (S 160  and S 170 ), injecting the electrolyte  115  between the first substrate  110  and the second substrate  100  (S 180 ), and sealing an inlet (S 190 ). Although the electrolyte solution  115  is injected between the first substrate  110  and the second substrate  100  after the first substrate  110  and the second substrate  100  are sealed in the present embodiment, the present invention is not limited thereto and the first substrate  110  and the second substrate  100  may be sealed after the electrolyte solution  115  is injected between the first substrate  110  and the second substrate  100 . 
         [0053]    An operation of forming the first electrode  210 , that is, the photocathode electrode, on the first substrate  110  will now be described. In S 110 , the first transparent conductive layer  111 , such as ITO or FTO, is formed on the first substrate  110  is formed of a transparent glass. In S 120 , the first grid electrodes  112  formed of silver (Ag) or aluminum (Al) are formed in parallel on the first transparent conductive layer  111 . The first grid electrodes  112  may have various patterns in addition to a stripe pattern. In S 130 , the protection film  160  is formed on the first grid electrodes  112  in order to protect the first grid electrodes  112 . In S 140 , the nano meter-sized semiconductor oxide layer  113  is formed on the first transparent conductive layer  11  and the protection film  160 . The nano meter-sized semiconductor oxide layer  113  may be a titanium dioxide (TiO 2 ) layer, a tin dioxide (SnO 2 ) layer, or a zinc oxide (ZnO) layer. In S 150 , the dye molecules  114  are adsorbed onto the nano meter-sized semiconductor oxide layer  113 . The dye molecules  114  are adsorbed onto the nano meter-sized semiconductor oxide layer  113  by soaking dye into the nano mete sized semiconductor oxide layer  113  of the first substrate  110 . 
         [0054]    An operation of forming the second electrode  200  that is the opposite electrode on the second substrate  100  will now be described. In S 111 , the second transparent conductive layer  101 , such as ITO or FTO, is formed on the second substrate  100  formed of a transparent glass. In S 121 , the second grid electrodes  102  formed of silver (Ag) or aluminum (Al) are formed in parallel on the second transparent conductive layer  101 . The second grid electrodes  102  may have various patterns in addition to a stripe pattern. In S 131 , the protection film  160  is formed on the second grid electrodes  102  in order to protect the second grid electrodes  102 . In S 141 , the catalyst film  103  is formed on the second grid electrodes  102  and the protection film  160 . The catalyst film  103  may be a platinum (Pt) thin film or a copper (C) thin film. 
         [0055]    The present invention is not limited to the above methods of forming the photocathode electrode  210  and the opposite electrode  200 . A modification or change of methods of forming the photocathode electrode  210  and the opposite electrode  200  by one of ordinary skill in the art may be considered to also be within the scope of the present invention. 
         [0056]    A method of forming a sealant  130  according to an embodiment of the present invention will now be described with reference to  FIGS. 4A through 4D . Referring to  FIG. 4A , a glass frit paste  131 ′ is applied along the boundary of the second substrate  100  in order to form the first sealing layer  131 . The glass frit paste  131 ′ is a paste in which vehicles and a glass frit are mixed. The glass frit paste  131 ′ is applied by using a screen printing method or a dispensing method. Referring to  FIG. 4B , the glass frit paste  131  is dried and baked at a temperature of between about 450 and about 600° C. A paste  132 ′ is applied onto the first sealing layer  131  in order to form the second sealing layer  132 . Referring to  FIG. 4C , the paste  132 ′ includes the glass frit paste  131 ′ and a laser absorption material, for example, manganese (Mn), iron (Fe), vanadium (V), chromium (Cr), nickel (Ni), cobalt (Co), or copper (Cu). Referring to  FIG. 4D , a laser beam is irradiated onto the second sealing layer  132  after the first substrate  110  is combined with the second sealing layer  132 . The laser absorption material of the second sealing layer  132  absorbs the laser beam and is heated, and thus a sealing operation is completed. 
         [0057]    A method of forming the sealant  230  according to another embodiment will now be described with reference to  FIGS. 4A ,  4 B,  4 C, and  4 E. The sealant  230  is formed of an organic-based resin material, whereas the sealant  130  is formed of an inorganic-based resin material. Operations shown in  FIGS. 4A and 4B  are the same as described with reference to the sealant  130 . However, since the sealant  230  is formed of the organic-based resin material that may be, for example, an epoxy resin material, an acrylic resin material, an olefin-acrylic based resin material, an olefin-acrylic-ion based resin material, or an olefin-based resin material, the glass frit paste  131  is heated and the glass frit paste  131  is pressed at a temperature of between about 100 and about 150° C. instead of being irradiated by a laser beam. 
         [0058]    A method of forming the sealant  130  according to another embodiment will now be described with reference to  5 A through  5 D. Referring to  FIG. 5A , the glass frit paste  131 ′ is applied along the peripheries of inner surfaces of the second substrate  100  in order to form the first sealing layer  131 . The method of forming and applying the glass frit paste  131 ′ is the same as described with reference to HG.  4 A. Referring to  FIG. 5B , the glass frit paste  131 ′ is dried and baked at a predetermined temperature. Referring to  FIG. 5C , the paste  132 ′ is applied onto the first substrate  110  in order to form the second sealing layer  132 . The second sealing layer  132  is disposed to face the first sealing layer  131 . The first substrate  110  and the second substrate  100  are combined with each other so that the first sealing layer  131  and the second sealing layer  132  face each other. Referring to  FIG. 5D , a laser beam is irradiated onto the second sealing layer  132 . The laser absorption material of the second sealing layer  132  absorbs the laser beam and is heated, and thus a sealing operation is completed. 
         [0059]    A method of forming the sealant  230  according to another embodiment will now be described with reference to  FIGS. 5A ,  5 B,  5 C, and  5 E. Referring to  FIG. 5A , a glass frit paste  131 ′ is applied along the boundary of the second substrate  100 . The method of forming and applying the glass fit paste  131 ′ is the same as described with reference to  FIG. 4A . Referring to  FIG. 5B , the glass frit paste  131 ′ is dried and heated at a predetermined temperature. Referring to  FIG. 5C , an organic-based resin is applied on the first substrate  110  in order to form a second sealing layer  133 . The second sealing layer  233  is disposed to face the first sealing layer  131 . Referring to  FIG. 5E , the first substrate  110  and the second substrate  100  are aligned so that the first sealing layer  131  and the second sealing layer  133  face each other, the second seating layer  133  is heated and pressed at a temperature of between approximately 100 and approximately 150° C. 
         [0060]    It should be understood that the exemplary embodiments described herein should be considered for descriptive purposes only, and are not intended to limit the claimed invention. Description of features or aspects within each embodiment should typically be considered as available for other similar features or aspects in other embodiments.