Patent Publication Number: US-2018053910-A1

Title: Optical device

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a Continuation Application of U.S. application Ser. No. 14/779,786, filed Sep. 24, 2015, which is a U.S. National Stage entry of PCT Application No. PCT/JP2014/058374, filed on Mar. 25, 2014, which claims priority to Japanese Patent Application No. 2013-075996, filed Apr. 1, 2013, the contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     The present invention relates to an optical device that uses an optical element such as a liquid crystal element and an organic EL (electroluminescence) element. 
     BACKGROUND ART 
     An optical device is used as various illuminating devices or displays. Generally, it is necessary for the optical device to have a joining structure that joins different materials such as terminals and interconnections for transmission of an electrical signal that drives the optical element. For example, the organic EL element, which is an example of an optical element, includes a transparent electrode, another electrode that is disposed to face the transparent electrode, and an organic layer that is interposed between the electrodes. As a technology relating to the organic EL element, for example, there are technologies which are described in Patent Document 1 and Patent Document 2. 
     In the technology described in Patent Document 1, a connection structure between an electrode formed on a light-emitting function layer and a lead-out electrode that supplies a display signal to the electrode is formed through fusion joining. Specifically, Patent Document 1 discloses a configuration in which a negative electrode that is constituted by a metal electrode layer, and a metal lead-out electrode layer are fused and joined at the connection portion through localized heating with laser light. 
     Patent Document 2 describes a light-emitting element including an electrode that is constituted by a metal line that is formed in a linear shape, and a polymer line that covers an upper surface and a lateral surface of the metal line. 
     RELATED DOCUMENT 
     Patent Document 
     [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2003-264064 
     [Patent Document 2] Japanese Unexamined Patent Application Publication No. 2006-93123 
     SUMMARY OF THE INVENTION 
     In the joining structure in which a first conductive film and a second conductive film are joined to each other, high contact resistance may occur between the first conductive film and the second conductive film. In this case, connection reliability between the first conductive film and the second conductive film deteriorates, and thus there is a concern that power consumption of the optical device may increase. 
     As an example, a problem to be solved by the invention is to reduce power consumption of the optical device by improving the connection reliability between two conductive films which are joined to each other. 
     According to the invention, there is provided an optical device including a joining structure in which a first conductive film that is constituted by a conductive material and a second conductive film that is constituted by a metal material are joined to each other. In the joining structure, a transition region, in which the conductive material and the metal material are mixed, exists between the first conductive film and the second conductive film. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and other objects, advantages and features of the present invention will be more apparent from the following description of certain preferred embodiments taken in conjunction with the accompanying drawings. 
         FIG. 1  is a plan view illustrating a light-emitting device according to a first embodiment. 
         FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 . 
         FIG. 3  is a cross-sectional view taken along line B-B in  FIG. 1 . 
         FIG. 4  is a view illustrating a part of the light-emitting device illustrated in  FIG. 1 . 
         FIG. 5  is a view illustrating a part of the light-emitting device illustrated in  FIG. 1 . 
         FIG. 6  is a view illustrating an example of a joining structure that is constituted by a first conductive film and a second conductive film in the first embodiment. 
         FIG. 7  is a view illustrating an example of a joining structure that is constituted by the first conductive film and the second conductive film in the first embodiment. 
         FIG. 8  is a plan view illustrating a light-emitting device according to a second embodiment. 
         FIG. 9  is a cross-sectional view taken along line C-C in  FIG. 8 . 
         FIG. 10  is a cross-sectional view taken along line D-D in  FIG. 8 . 
         FIG. 11  is a view illustrating a part of the light-emitting device illustrated in  FIG. 8 . 
         FIG. 12  is a plan view illustrating a configuration of a light-emitting device according to a third embodiment. 
         FIG. 13  is a cross-sectional view illustrating a configuration of an optical device according to a fourth embodiment. 
         FIG. 14  is a plan view of the optical device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, embodiments of the invention will be described with reference to the accompanying drawings. In all of the drawings, the same reference numerals will be given to the same constituent elements, and description thereof will be appropriately omitted. 
     First Embodiment 
       FIG. 1  is a plan view illustrating an optical device  10  according to a first embodiment.  FIG. 2  is a cross-sectional view taken along line A-A in  FIG. 1 , and  FIG. 3  is a cross-sectional view taken along line B-B in  FIG. 1 . 
     In addition,  FIGS. 4 and 5  are views illustrating a part of the optical device  10  illustrated in  FIG. 1 . In  FIG. 4 , particularly, a positional relationship between a first conductive film  110  and a second conductive film  130  is illustrated. In addition, in  FIG. 5 , a configuration of an insulating layer  120  is illustrated.  FIGS. 6 and 7  are views illustrating an example of a joining structure  200  that is constituted by the first conductive film  110  and the second conductive film  130  in this embodiment. In this embodiment, the optical device  10  is, for example, a light-emitting device such as an illuminating device and a display. Hereinafter, description will be given of the optical device  10  as a light-emitting device  10 . 
     The joining structure  200  has a configuration in which the first conductive film  110  constituted by a transparent conductive material and a second conductive film  130  constituted by a metal material are joined to each other. In addition, a transition region, in which the transparent conductive material and the metal material are mixed, exists between the first conductive film  110  and the second conductive film  130 . 
     In addition, the light-emitting device  10  according to this embodiment includes the joining structure  200 . The light-emitting device  10  includes an organic EL element  20 , a first interconnection  114  and a lead-out interconnection  134 . The organic EL element  20  includes a first electrode  112 , a second electrode  152 , and an organic layer  140  that is disposed between the first electrode  112  and the second electrode  152 . The first interconnection  114  is electrically connected to the first electrode  112 , and is constituted by the first conductive film  110 . The lead-out interconnection  134  is joined to the first interconnection  114 , and is constituted by the second conductive film  130 . 
     Hereinafter, an example of a configuration of the joining structure  200 , an example of a configuration of the light-emitting device  10 , and an example of a method of manufacturing the light-emitting device  10  according to the this embodiment will be described in detail. 
     First, the example of the configuration of the joining structure  200  according to this embodiment will be described. 
     The joining structure  200  is a joining structure in which the first conductive film  110  and the second conductive film  130  are joined to each other. Further, in this specification, the joining between the first conductive film  110  and the second conductive film  130  includes a case where another configuration is interposed between the first conductive film  110  and the second conductive film  130 . 
     In this embodiment, the joining structure  200  is formed, for example, on a substrate  100 . In this case, the first conductive film  110  and the second conductive film  130  are formed on the substrate  100 . 
     For example, the joining structure  200  constitutes a light-emitting device that includes an organic EL element. For example, the light-emitting device includes an organic EL element, a first interconnection that is electrically connected to an electrode that constitutes the organic EL element, and a lead-out interconnection that is electrically connected to the first interconnection. At this time, an electrical signal, which controls light-emission and non-light-emission, is supplied to the electrode that constitutes the organic EL element from the outside through the lead-out interconnection and the first interconnection. 
     In this embodiment, the first conductive film  110  in the joining structure  200  constitutes, for example, the first interconnection that is connected to the electrode that constitutes the organic EL element. In addition, the second conductive film  130  in the joining structure  200  constitutes, for example, a lead-out interconnection. In this case, the joining structure  200  is formed between the first interconnection and the lead-out interconnection. 
     The first conductive film  110  substantially includes a conductive material. Examples of the conductive material, which constitutes the first conductive film  110 , include a transparent conductive material, and paste-like conductive materials such as silver. Among these, the transparent conductive material is particularly preferable. In a case where the first conductive film  110  is constituted by the transparent conductive material, a conductive film having transparency is obtained. In this embodiment, for example, the first conductive film  110  has a shape that extends in a direction parallel to a plane of the substrate  100 . 
     For example, the transparent conductive material includes an inorganic material such as indium tin oxide (ITO) and indium zinc oxide (IZO), or a conductive polymer. 
     In a case where the transparent conductive material includes the conductive polymer, the first conductive film  110  can be formed by using a coating method. In this case, in a process of forming the first conductive film  110 , it is possible to suppress a thermal load from being applied to other configurations such as the substrate  100 . 
     In addition, in a case where the inorganic material is included as the transparent conductive material, it is preferable that the first conductive film  110  is a coating-type conductive film that is formed through application of a solution in which the inorganic material is dispersed in an organic solvent. Even in this case, the first conductive film  110  can be formed by using the coating method. 
     In this embodiment, examples of the conductive polymer, which is included in the transparent conductive material that constitutes the first conductive film  110 , include a conductive polymer that includes a n-conjugated conductive polymer and a polyanion. In this case, it is possible to form the first conductive film  110  that is particularly excellent in conductivity, heat resistance, and flexibility. 
     Although not particularly limited, examples of the n-conjugated conductive polymer that can be used include chain-line conductive polymers such as polythiophenes, polypyrroles, polyindoles, polycarbazoles, polyanilines, polyacetylenes, polyfurans, polyparaphenylene vinylenes, polyazulenes, polyparaphenylenes, polyparaphenylene sulfides, polyisothianaphthenes, and polythiazyls. The polythiophenes or the polyanilines are preferable from the viewpoints of conductivity, transparency, stability, and the like, and polyethylenedioxythiophene is more preferable. 
     Examples of the polyanion, which can be used, include polyvinyl sulfonic acid, polystyrene sulfonic acid, polyallyl sulfonic acid, polyacrylic acid ethyl sulfonic acid, polyacrylic acid butyl sulfonic acid, poly-2-acrylamide-2-methylpropane sulfonic acid, polyisoprene sulfonic acid, polyvinyl carboxylic acid, polystyrene carboxylic acid, polyallyl carboxylic acid, polyacrylic carboxylic acid, polymethacrylic carboxylic acid, poly-2-acrylamide-2-methylpropane carboxylic acid, polyisoprene carboxylic acid, and polyacrylic acid. The polyanions, which can be used in this embodiment, may be homopolymers thereof, or copolymers of two or more kinds thereof. 
     In a case where the conductive polymer is included as the transparent conductive material that constitutes the first conductive film  110 , the transparent conductive material may further contain a cross-linking agent, a leveling agent, a antifoaming agent, and the like. 
     The second conductive film  130  includes a metal material. Here, as the metal material that is included in the second conductive film  130 , for example, a metal material having electric resistance lower than that of the transparent conductive material that constitutes the first conductive film  110  is used. In this case, the first conductive film  110  and the second conductive film  130  are constituted by materials different from each other. 
     Examples of the metal material, which is included in the second conductive film  130 , include Ag, Al, Cr, Mo, Ni, Nb, Ti, W, Au, Pt, Cu, and Pd. Further, the second conductive film  130  is, for example, a sintered body that is obtained through sintering of metal particles. 
     A transition region, in which the transparent conductive material that constitutes the first conductive film  110 , and the metal material that constitutes the second conductive film  130  are mixed, exists between the first conductive film  110  and the second conductive film  130 . 
     Here, the aspect in which the transparent conductive material and the metal material are mixed includes an aspect in which the metal material that constitutes the second conductive film  130  is spread into the first conductive film  110 . At this time, the aspect in which the metal material is spread into the first conductive film  110  includes both a case where the a continuous body of the metal material, which is connected to the second conductive film  130  and extends toward the first conductive film  110 , is formed, and a case where the metal material separated from the second conductive film  130  is dispersed inside the first conductive film  110 . 
     In addition, in a case where the transparent conductive material and the metal material are mixed, the transparent conductive material, which constitutes the first conductive film  110 , may be spread into the second conductive film  130 . At this time, the aspect in which the transparent conductive material is spread into the second conductive film  130  includes both a case where a continuous body of the transparent conductive material, which is connected to the first conductive film  110  and extends toward the second conductive film  130 , is formed, and a case where the transparent conductive material separated from the first conductive film  110  is dispersed inside the second conductive film  130 . 
     The transition region represents a region that occupies a constant space between the first conductive film  110  and the second conductive film  130 . In the space that is an example of the transition region in the embodiment, the transparent conductive material and the metal material exist in all cross-sections having a normal line that extends in an extension direction of the first conductive film  110 , and in any of all planes parallel to the plane of the substrate  100 . 
     According to this embodiment, a transition region, in which the transparent conductive material that constitutes the first conductive film  110  and the metal material that constitutes the second conductive film  130  are mixed exists between the first conductive film  110  and the second conductive film  130 . According to this, a contact area between the first conductive film  110  and the second conductive film  130  increases, and thus it is possible to reduce contact resistance therebetween. Accordingly, it is possible to improve contact reliability between the first conductive film  110  and the second conductive film  130 . 
     Apart of the first conductive film  110  overlaps the second conductive film  130 , for example, when seen in a plan view. At this time, for example, in a stacking region in which the first conductive film  110  and the second conductive film  130  are stacked on each other, the transition region in which the transparent conductive material and the metal material are mixed is formed. In addition, the joining structure  200 , in which the first conductive film  110  and the second conductive film  130  are joined to each other, includes the stacking region. 
     In this embodiment, the first conductive film  110  is formed in such a manner that one end of the first conductive film  110  overlaps a part of the second conductive film  130 , and thus the stacking region is formed. In this case, for example, the first conductive film  110  is formed to cover a part of each of an upper surface and a lateral surface of the second conductive film  130 . 
       FIGS. 6 and 7  illustrate a configuration of the stacking region in which the first conductive film  110  and the second conductive film  130  are stacked on each other. 
     An example illustrated in  FIG. 6  is an example in which only a part of the metal material that constitutes a portion of the second conductive film  130 , which is located in the stacking region, is spread into the first conductive film  110 . At this time, only a part of the transparent conductive material that constitutes a portion of the first conductive film  110 , which is located in the stacking region, is spread into the second conductive film  130 . In the stacking region, both of the first conductive film  110  and the second conductive film  130  maintain a film shape. 
       FIG. 7  illustrates an example in which a degree of diffusion of the metal material to the inside of the first conductive film  110  in the stacking region is greater than that in the example illustrated in  FIG. 6 . In this case, a degree of diffusion of the transparent conductive material to the inside of the second conductive film  130  in the stacking region is also greater than that in the example illustrated in  FIG. 6 . At this time, the film thickness of the second conductive film  130  in the stacking region becomes smaller in comparison to, for example, the case illustrated in  FIG. 6 . In addition, for example, the film thickness of the first conductive film  110  in the stacking region also becomes smaller in comparison to the case illustrated in  FIG. 6 . 
     In the examples illustrated in  FIGS. 6 and 7 , in the second conductive film  130 , a linked body may be formed, in which metal particles dispersed to the inside of the first conductive film  110  from the second conductive film  130  are subjected to grain growth and become connected to each other. 
     According to this, a protrusion constituted by the linked body is formed on a surface of the second conductive film  130 . In addition, the linked body may have, for example, a dendritic shape. For example, metal particles, which are spread from the second conductive film  130  to the inside of the first conductive film  110  and are separated from the second conductive film  130 , exist at the inside of the first conductive film  110 . 
     Further, a degree of spreading of the transparent conductive material and the metal material in the transition region is not particularly limited. As illustrated in  FIGS. 6 and 7 , the transparent conductive material and the metal material may be spread to a certain extent at which at least a part of the first conductive film  110  and at least a part of the second conductive film  130  are capable of maintaining a film shape. In addition, the transparent conductive material and the metal material may be spread to a certain extent at which the first conductive film  110  and the second conductive film  130  do not maintain the film shape. 
     In this embodiment, for example, the joining structure  200 , in which the first conductive film  110  and the second conductive film  130  are joined to each other, is formed as follows. 
     First, the second conductive film  130  is formed on the substrate  100 . For example, the second conductive film  130  is formed by applying a coating solution containing metal particles onto the substrate  100  by using a coating method. The coating method that is used in the process is not particularly limited and examples thereof include an ink-jet method, a screen printing method, a spray coating method, and a dispenser coating method. In addition, for example, the coating solution, which is used in the process of forming the second conductive film  130 , includes a binder resin and an organic solvent. As the binder resin, for example, a cellulose-based resin, an epoxy-based resin, or an acryl-based resin can be used. As the organic solvent, for example, a hydrocarbon-based solvent, or an alcohol-based solvent can be used. In addition, examples of the metal particles, which are contained in the coating solution, include Ag, Al, Cr, Mo, Ni, Nb, Ti, W, Au, Pt, Cu, or Pd. 
     Next, the first conductive film  110  is formed on the substrate  100 . For example, the first conductive film  110  is formed by applying a coating solution that contains the transparent conductive material onto the substrate  100 , and drying the coating solution. For example, the first conductive film  110  is formed to cover a part of the second conductive film  130 . 
     Although not particularly limited, the coating solution that contains the transparent conductive material is applied onto the substrate  100  by using an ink-jet method, a screen printing method, a letterpress printing method, a gravure printing method, die coating, spin coating, or spraying. The coating solution that contains the transparent conductive material, which is used in the process of forming the first conductive film  110 , includes an organic solvent, water, or the like in addition to the above-described transparent conductive material. As the organic solvent, for example, an alcohol-based solvent can be used. 
     In this embodiment, the process of forming the first conductive film  110  is carried out, for example, in a non-sintered state in which the second conductive film  130  has not been sintered. At this time, at a portion in which the second conductive film  130  and the first conductive film  110  come into contact with each other, metal particles are spread to the inside of the first conductive film  110  from the second conductive film  130  in a non-sintered state. In addition, at this time, at a portion in which the second conductive film  130  and the first conductive film  110  come into contact with each other, the transparent conductive material is spread to the inside of the second conductive film  130  from the first conductive film  110 . According to this, the transition region, in which the transparent conductive material and the metal material are mixed, is formed between the first conductive film  110  and the second conductive film  130 . 
     Next, a heat treatment is carried out with respect to the first conductive film  110  and the second conductive film  130 . According to this, the second conductive film  130  is sintered, and the first conductive film  110  is dried. In a case where the transparent conductive material includes a conductive polymer, when the first conductive film  110  is dried, a cohesive force of the conductive polymer increases and thus it is possible to form the first conductive film  110  as a strong film. In addition, when the heat treatment is carried out with respect to the first conductive film  110 , the first conductive film  110  is cured. This heat treatment is carried out, for example, under conditions of 120° C. to 250° C. and 2 minutes to 60 minutes. In addition, in a case where the transparent conductive material that constitutes the first conductive film  110  includes a photosensitive material, the first conductive film  110  may be cured through UV irradiation. 
     In this embodiment, the heat treatment is carried out in a state in which the metal particles are spread to the inside of the first conductive film  110  from the second conductive film  130  in a non-sintered state. The metal particles, which are spread to the inside of the first conductive film  110 , may be subjected to grain growth by the heat treatment, thus forming a linked body in which the metal particles are connected to each other. In this case, a linked body, in which the metal particles are connected to each other after grain growth, is formed in the second conductive film  130 . 
     Next, an example of a configuration of the light-emitting device  10  will be described. 
       FIG. 1  illustrates a case in which the light-emitting device  10  is a display. 
     Further, the light-emitting device  10  may be an illuminating device. In a case where the light-emitting device  10  is an illuminating device, for example, the light-emitting device  10  has a configuration in which a plurality of linear organic layers  140  having light emission colors different from each other are repetitively arranged. According to this, an illuminating device, which is excellent in color rendering properties, is realized. In addition, the light-emitting device  10 , which is the illuminating device, may include a sheet-shaped organic layer  140 . 
     For example, the substrate  100  is a transparent substrate. In this embodiment, the substrate  100  may be configured as a glass substrate. According to this, it is possible to manufacture the light-emitting device  10  excellent in heat resistance and the like at a low cost. 
     The substrate  100  may be a film-shaped substrate that is constituted by a resin material. In this case, particularly, it is possible to realize a display with high flexibility. Examples of the resin material that constitutes the film-shaped substrate include polyethylene terephthalate, polyethylene naphthalate, and polycarbonate. In addition, the substrate  100  may be a combination of glass and a resin material. According to this embodiment, even when the optical device (light-emitting device  10 ) has flexibility, connection reliability in the joining structure  200  constituted by the first conductive film  110  and the second conductive film  130  is high, and thus an effect of reducing power consumption is high. 
     For example, the light-emitting device  10 , which is a display, includes a plurality of the organic EL elements  20  which are arranged in an array shape on the substrate  100 . Each of the organic EL elements  20  includes the first electrode  112  that is provided on the substrate  100 , the organic layer  140  that is provided on the first electrode  112 , and the second electrode  152  that is provided on the organic layer  140 . At this time, the organic layer  140  is interposed between the first electrode  112  and the second electrode  152 . 
     In this embodiment, for example, a plurality of the first electrodes  112  which extend in a Y-direction in the drawing, and a plurality of the second electrodes  152  which extend in an X-direction in the drawing are provided on the substrate  100 . In addition, the organic EL element  20  is formed at each portion in which each of the first electrodes  112  and each of the second electrodes  152  overlap each other when seen in a plan view. According to this, a plurality of the organic EL elements  20 , which are arranged in an array shape, are formed on the substrate  100 . 
     The first electrode  112  becomes, for example, a positive electrode of the organic EL element. In this case, for example, the first electrode  112  becomes a transparent electrode that is transparent or translucent with respect to a wavelength of light emitted from a light-emitting layer  144  of the organic layer  140  to be described later. In addition, for example, on the substrate  100  and within a pixel region  300 , the first electrode  112  is provided to extend in a linear shape in the Y-direction in the drawing. In addition, for example, the plurality of first electrodes  112 , which are spaced away from each other, are arranged on the substrate  100  in a direction (X-direction in the drawing) perpendicular to the extension direction of the first electrodes  112 . At this time, for example, the plurality of first electrodes  112  are spaced away from each other. Further, the pixel region  300  is a region including the plurality of organic EL elements  20 . In an example illustrated in  FIG. 4 , a region surrounded by a one-dot chain line corresponds to the pixel region  300 . 
     In this embodiment, for example, the first electrode  112  is constituted by a transparent conductive material. As the transparent conductive material that constitutes the first electrode  112 , for example, a transparent conductive material, which is the same as the transparent conductive material that constitutes the first conductive film  110 , can be used. According to this, the first electrode  112  can have transparency. 
     For example, the first interconnection  114  is provided on the substrate  100 . In this embodiment, a case where the first interconnection  114  is electrically connected to the first electrode  112  is exemplified. At this time, a plurality of the first interconnections  114 , which are respectively connected to different ones of the first electrodes  112 , are provided on the substrate  100 . According to this, each of the plurality of first electrodes  112  in this embodiment is connected to the lead-out interconnection  134  through each of the first interconnections  114 . 
     In this embodiment, the first interconnection  114  is constituted by the first conductive film  110  that is constituted by a transparent conductive material. According to this, the first interconnection  114  can have transparency. 
     In this embodiment, for example, the first electrode  112  and the first interconnection  114  are integrally provided on the substrate  100 . In this case, for example, the first interconnection  114  and the first electrode  112  are constituted by the first conductive film  110 . At this time, a portion of the first conductive film  110 , which is located in the pixel region  300  including the plurality of organic EL elements  20 , becomes the first electrode  112 . In addition, a portion of the first conductive film  110 , which is located outside the pixel region  300 , becomes the first interconnection  114 . The first electrode  112  is connected to the lead-out interconnection  134  through the first interconnection  114 . 
     In the example illustrated in  FIG. 4 , a plurality of first conductive films  110 , which extend in the Y-direction in the drawing, are provided on the substrate  100 . The plurality of first conductive films  110  are arranged in the X-direction in the drawing so as to be spaced away from each other. In addition, a portion of the first conductive film  110 , which is located further on an end side that is connected to the lead-out interconnection  134  than the pixel region  300  indicated by the one-dot chain line, becomes the first interconnection  114 . 
     The lead-out interconnection  134  is provided on the substrate  100 . 
     In this embodiment, a case where the lead-out interconnection  134  and the first interconnection  114  are connected to each other is exemplified. A plurality of the lead-out interconnections  134 , which are arranged in the X-direction in the drawing and are spaced away from each other, are provided on the substrate  100 . Each of the lead-out interconnections  134  is connected to each of the first interconnections  114 . According to this, each of the plurality of first interconnections  114  is connected to an external side through each of the lead-out interconnections  134 . A signal for light-emission or non-light-emission is supplied to the organic EL element  20  through the first interconnection  114  and the lead-out interconnection  134 . 
     In this embodiment, the lead-out interconnection  134  is constituted by the second conductive film  130  that is constituted by a metal material. According to this, in a case where the lead-out interconnection  134  and the first interconnection  114  are connected to each other, the first interconnection  114  that is constituted by the first conductive film  110  and the lead-out interconnection  134  that is constituted by the second conductive film  130  are joined to each other, thereby forming the joining structure  200 . In the example illustrated in  FIG. 4 , the joining structure  200  is formed at a portion that is surrounded by a broken line. 
     The first interconnection  114  is connected to the lead-out interconnection  134  at one end. At this time, for example, the first interconnection  114  and the lead-out interconnection  134  are joined to each other at the one end, thereby forming the joining structure  200 . The first interconnection  114  extends in a first direction when seen from the lead-out interconnection  134 . Further, the first direction in this embodiment indicates, for example, the Y-direction in the drawing. 
     In this embodiment, a part of the first interconnection  114  overlaps, for example, the lead-out interconnection  134  when seen in a plan view. At this time, for example, a transition region, in which a transparent conductive material and a metal material are mixed, is formed in a stacking region in which the first interconnection  114  that is constituted by the first conductive film  110  and the lead-out interconnection  134  that is constituted by the second conductive film  130  are stacked on each other. In addition, the joining structure  200 , in which the first conductive film  110  and the second conductive film  130  are joined to each other, includes the stacking region. In this embodiment, the first interconnection  114  is formed in such a manner that one end of the first interconnection  114  overlaps a part of the lead-out interconnection  134 , thereby forming the stacking region. In this case, for example, the first interconnection  114  is formed to cover each of parts of an upper surface and a lateral surface of the lead-out interconnection  134 . 
       FIG. 4  illustrates a case where only an end of the lead-out interconnection  134  on a pixel region  300  side overlaps the first interconnection  114  when seen in a plan view. In this case, the end of the lead-out interconnection  134  on the pixel region  300  side is covered with the first interconnection  114  and the other portion is exposed without being covered with the first interconnection  114 . In this embodiment, the lead-out interconnection  134  is covered with the first interconnection  114 , for example, at a part of the upper surface, an end surface that faces the pixel region  300 , and a part of two lateral surfaces which are adjacent to the end surface. 
     For example, the insulating layer  120  is provided on the substrate  100  to cover the first electrode  112 . In this embodiment, the insulating layer  120  is provided to cover, for example, a part of each of the first electrode  112 , the first interconnection  114 , and a lead-out interconnection  164  to be described later. 
     The insulating layer  120  is a photo-sensitive resin such as a polyimide-based resin, and is formed in a desired pattern through exposure and development. The insulating layer  120  may be constituted by a resin material other than the polyimide-based resin, and may be an epoxy-based resin or an acryl-based resin. 
     The insulating layer  120  is provided with, for example, a plurality of first openings  122 . As illustrated in  FIG. 5 , the first openings  122  are formed to constitute, for example, a matrix. 
     In this embodiment, the plurality of first openings  122  are formed to be located on the first electrode  112 . On each of the first electrodes  112  which extend in the Y-direction in the drawing, for example, the plurality of first openings  122  are arranged in the Y-direction with a predetermined gap therebetween. In addition, for example, the plurality of first openings  122  are provided at a position that overlaps a second electrode  152  that extends in a direction (X-direction in the drawing) orthogonal to the first electrode  112 . According to this, the plurality of first openings  122  are arranged to constitute a matrix. 
     For example, a plurality of second openings  124  are provided in the insulating layer  120 . 
     As illustrated in  FIG. 5 , for example, the second openings  124  are provided to be located on the lead-out interconnection  164 . The plurality of second openings  124  are arranged along one side of a matrix constituted by the first openings  122 . When seen in a direction (for example, the Y-direction in the drawing) along the one side, the second openings  124  are disposed at the same interval as the first openings  122 . 
     For example, a partition wall  170  is provided on the insulating layer  120 . 
     As illustrated in  FIG. 1 , the partition wall  170  is provided to extend in the X-direction in the drawing. That is, the partition wall  170  is formed along an extension direction of the second electrode  152 . In addition, a plurality of the partition walls  170  are provided to be arranged in the Y-direction in the drawing. 
     For example, the partition wall  170  is a photo-sensitive resin such as a polyimide-based resin, and is formed in a desired pattern through exposure and development. Further, the partition wall  170  may be constituted by a resin material other than the polyimide-based resin, and may be an epoxy-based resin or an acryl-based resin. 
     For example, a cross-section of the partition wall  170  has a shape (inverted trapezoidal shape) in which an upper side and a lower side of a trapezoid are inverted from each other. That is, a width of the upper surface of the partition wall  170  is greater than, for example, a width of a bottom surface of the partition wall  170 . In this case, even when collectively forming the plurality of second electrodes  152  by a sputtering method, a deposition method, and the like, it is possible to separate the plurality of second electrodes  152  from each other, each being located between adjacent partition walls  170 . Accordingly, it is possible to easily form the second electrodes  152 . 
     Further, a planar shape of the partition wall  170  is not limited to a shape illustrated in  FIG. 1 . Accordingly, by changing the planar shape of the partition wall  170 , it is possible to freely change a planar pattern of the plurality of second electrodes  152  which are separated from each other by the partition wall  170 . 
     As illustrated in  FIG. 2 , for example, the organic layer  140  is formed in the first openings  122 . 
     In this embodiment, for example, the organic layer  140  is constituted by a stacked body in which a hole injection layer  142 , a light-emitting layer  144 , and an electron injection layer  146  are sequentially stacked. At this time, the hole injection layer  142  comes into contact with the first electrode  112 , and the electron injection layer  146  comes into contact with the second electrode  152 . According to this, the organic layer  140  is interposed between the first electrode  112  and the second electrode  152 . 
     Further, a hole transport layer may be formed between the hole injection layer  142  and the light-emitting layer  144 , and an electron transport layer may be formed between the light-emitting layer  144  and the electron injection layer  146 . In addition, the organic layer  140  may not be provided with the hole injection layer  142 . 
     In this embodiment, for example, the partition wall  170  is provided on the insulating layer  120 . In this case, as illustrated in  FIG. 2 , with regard to the organic layer  140  that is provided in each of a plurality of regions interposed between adjacent partition walls  170 , the organic layers  140  are separated from each other in the Y-direction in the drawing. Further, for example, a stacked film, which is constituted by the same material as in the organic layer  140 , is formed on the partition wall  170 . 
     On the other hand, as illustrated in  FIG. 3 , the respective layers, which constitute the organic layer  140 , are provided to be continuous between the first openings  122  adjacent to each other in the X-direction in the drawing in which the partition wall  170  extends. 
     The second electrode  152  is provided on the organic layer  140 . 
     In this embodiment, for example, the second electrode  152  becomes a negative electrode of the organic EL element. For example, the second electrode  152  is provided to extend in a linear shape in the X-direction in the drawing. In addition, for example, a plurality of the second electrodes  152 , which are spaced away from each other, are arranged on the substrate  100  in a direction (Y-direction in the drawing) perpendicular to the extension direction of the second electrodes  152 . 
     For example, the second electrode  152  is constituted by a metal material such as tin, magnesium, indium, calcium, aluminum, silver, and alloys thereof. These materials may be used alone or in an arbitrary combination of two or more kinds thereof. Further, in a case where the second electrode  152  is a negative electrode, it is preferable that the second electrode  152  is constituted by a conductive material having a work function that is smaller than that of the first electrode  112  that is a positive electrode. 
     A second interconnection  154  is provided on the substrate  100 . 
     The second interconnection  154  is connected to either the first electrode  112  or the second electrode  152  which is not connected to the first interconnection  114 . According to this, either the first electrode  112  or the second electrode  152 , which is connected to the second interconnection  154 , is connected to the outside through the second interconnection  154 . 
     In this embodiment, a case where the second interconnection  154  is provided on the organic layer  140  and is connected to the second electrode  152  is exemplified. At this time, a plurality of the second interconnections  154 , which are respectively connected to different ones of the second electrodes  152 , are provided on the organic layer  140 . According to this, each of the plurality of second electrodes  152  in this embodiment is connected to the outside through each of the second interconnections  154 . Further, for example, apart of the second interconnection  154  is embedded in the second opening  124 , and is connected to the lead-out interconnection  164  to be described later. 
     For example, the second interconnection  154  is constituted by a metal material. As the metal material that constitutes the second interconnection  154 , for example, the same metal material as in the second electrode  152  can be used. 
     In this embodiment, for example, the second electrode  152  and the second interconnection  154  are integrally provided on the organic layer  140 , and constitute a conductive film  150 . In this case, a portion of the conductive film  150 , which is located in the pixel region  300  including the plurality of organic EL elements  20 , becomes the second electrode  152 . In addition, a portion of the conductive film  150 , which is located outside the pixel region  300 , becomes the second interconnection  154 . For example, the second electrode  152  is connected to the lead-out interconnection  164  through the second interconnection  154 . Further, in an example illustrated in  FIG. 1 , a region surrounded by a one-dot chain line corresponds to the pixel region  300 . 
     In the example illustrated in  FIG. 1 , a plurality of the conductive films  150 , which extend in the X-direction in the drawing, are provided on the organic layer  140 . In addition, the plurality of conductive films  150  are arranged in the Y-direction in the drawing so as to be spaced away from each other. In addition, a portion of each of the conductive films  150 , which is located further on an end side that is connected to the lead-out interconnection  164  than the pixel region  300 , becomes the second interconnection  154 . 
     For example, the plurality of conductive films  150  are collectively formed on the organic layer  140  by using a sputtering method, a deposition method, and the like. Even in this case, in this embodiment, the partition wall  170  is formed on the insulating layer  120 . Accordingly, the conductive films  150  which are provided in a plurality of regions interposed between adjacent partition walls  170  are separated from each other in the Y-direction in the drawing. 
     According to this, it is possible to form the plurality of conductive films  150  which are arranged in the Y-direction in the drawing to be spaced away from each other and extend in the X-direction in the drawing. At this time, a film that is constituted by the same material as in the conductive film  150  is formed on each of the partition walls  170 . 
     For example, the lead-out interconnection  164  is provided on the substrate  100 . The second interconnection  154  is connected to the outside through the lead-out interconnection  164 . According to this, the second electrode  152  is connected to the outside through the second interconnection  154  and the lead-out interconnection  164 , allowing a signal to be supplied thereto. 
     For example, the lead-out interconnection  164  is constituted by a metal material. As the metal material that constitutes the lead-out interconnection  164 , for example, the same metal material as in the lead-out interconnection  134  can be used. In this case, the lead-out interconnection  164  can be formed simultaneously with the lead-out interconnection  134 . According to this, it is possible to suppress an increase in the number of manufacturing processes of the light-emitting device  10 . Generally, an end of the lead-out interconnection  134  or  164  forms a terminal portion of the light-emitting device  10 . The terminal portion is electrically connected to an external circuit. An anisotropic conductive film (ACF) or a bonding wire is used for connection between the terminal portion and the outside. Particularly, in the optical device (light-emitting device  10 ) using the bonding wire, even in a case where the optical device has an irregular or circular shape, in addition to a rectangular shape, connection reliability in the joining structure  200  that is constituted by the first conductive film  110  and the second conductive film  130  is high, and thus an effect of reducing power consumption is high. 
     Next, description will be give of an example of a method of manufacturing the light-emitting device  10 . 
     First, the lead-out interconnection  134  is formed on the substrate  100 . For example, the lead-out interconnection  134  is formed by applying a coating solution that contains metal particles on the substrate  100  by using a coating method. Further, in this embodiment, the lead-out interconnection  134  is constituted by the second conductive film  130 . According to this, for example, the lead-out interconnection  134  is formed by using a method of forming the above-described second conductive film  130  and a material that constitutes the second conductive film  130 . 
     In addition, in this embodiment, for example, the lead-out interconnection  164  is formed on the substrate  100  simultaneously with the process of forming the lead-out interconnection  134 . In this case, for example, the lead-out interconnection  164  is formed by the same method and the same material as those of the lead-out interconnection  134 . 
     Next, the first interconnection  114  is formed on the substrate  100 . For example, the first interconnection  114  is formed by applying a coating solution that contains a transparent conductive material on the substrate  100 , and by drying the coating solution. In addition, in this embodiment, the first interconnection  114  is the first conductive film  110 . According to this, the first interconnection  114  is formed by using, for example, a method of forming the above-described first conductive film  110 , and a material that constitutes the first conductive film  110 . 
     In this embodiment, the process of forming the first interconnection  114  is carried out, for example, in a non-sintered state in which the lead-out interconnection  134  has not been sintered. At this time, at a portion at which the lead-out interconnection  134  and the first interconnection  114  come into contact with each other, the metal particles are spread from the lead-out interconnection  134  in the non-sintered state to the inside of the first interconnection  114 . In addition, at a portion at which the lead-out interconnection  134  and the first interconnection  114  come into contact with each other, the transparent conductive material spreads from the first interconnection  114  to the inside of the lead-out interconnection  134 . According to this, a transition region, in which the transparent conductive material and the metal material are mixed, is formed between the first conductive film  110  that constitutes the first interconnection  114  and the second conductive film  130  that constitutes the lead-out interconnection  134 . 
     In the process of forming the first interconnection  114 , for example, the first electrode  112  that is connected to the first interconnection  114  is formed together with the first interconnection  114 . In this case, for example, the first electrode  112  is formed integrally with the first interconnection  114  to be constituted by the first conductive film  110 . 
     Next, a heat treatment is carried out with respect to the first interconnection  114  and the lead-out interconnection  134 . According to this, the lead-out interconnection  134  is sintered and the first interconnection  114  is dried. This heat treatment is carried out, for example, under conditions of 120° C. to 250° C., and 2 minutes to 60 minutes. 
     In this embodiment, the heat treatment is carried out in a state in which the metal particles are spread from the lead-out interconnection  134  in a non-sintered state to the inside of the first interconnection  114 . At this time, the metal particles which are spread to the inside of the first interconnection  114  may become a linked body in which the metal particles are connected to each other through grain growth by the heat treatment. In addition, the metal particles which are spread to the inside of the first interconnection  114  may exist in a state of being separated from the second conductive film  130  without constituting the linked body. A structure that is obtained at this stage is illustrated in  FIG. 4 . 
     Next, the insulating layer  120  is formed on the substrate  100 , the first electrode  112 , the first interconnection  114 , and the lead-out interconnection  164 . The insulating layer  120  is patterned into a predetermined shape by using dry-etching, wet-etching, or the like. According to this, the plurality of first openings  122  and the plurality of second openings  124  are formed in the insulating layer  120 . At this time, for example, the plurality of first openings  122  are formed in such a manner that a part of the first electrode  112  is exposed from each of the first openings  122 . 
     Next, the partition wall  170  is formed on the insulating layer  120 . The partition wall  170  is obtained by patterning the insulating film provided on the insulating layer  120  into a predetermined shape by using dry-etching, wet-etching, or the like. In a case where the partition wall  170  is formed from a photo-sensitive resin, it is possible to allow the partition wall  170  to have an inverted trapezoidal cross-sectional shape by adjusting conditions during exposure and development. A structure that is obtained at this stage is illustrated in  FIG. 5 . 
     Next, the hole injection layer  142 , the light-emitting layer  144 , and the electron injection layer  146  are sequentially formed in the first openings  122 . These may be formed by using, for example, a coating method or a deposition method. 
     According to this, the organic layer  140  is formed. 
     Next, the conductive film  150 , which constitutes the second electrode  152  and the second interconnection  154 , is formed on the organic layer  140 . At this time, for example, the conductive film  150  is formed in such a manner that a part of the conductive film  150  is located inside the second openings  124 . The conductive film  150  is formed by using, for example, a deposition method or a sputtering method. 
     According to this, the organic EL element  20 , which is constituted by the first electrode  112 , the second electrode  152 , and the organic layer  140  that is interposed between the first electrode  112  and the second electrode  152 , is formed on the substrate  100 . 
     In this embodiment, for example, the light-emitting device  10  is formed as described above. 
     As described above, according to this embodiment, the transition region, in which the transparent conductive material that constitutes the first conductive film  110  and the metal material that constitutes the second conductive film  130  are mixed, exists between the first conductive film  110  and the second conductive film  130 . According to this, a contact area between the first conductive film  110  and the second conductive film  130  increases, and thus it is possible to reduce a contact resistance therebetween. According to this, it is possible to improve connection reliability between the first conductive film  110  and the second conductive film  130 . 
     In addition, it is possible to realize the light-emitting device  10  including the first interconnection  114  that is connected to the first electrode  112  constituting the organic EL element  20  and is constituted by the first conductive film  110 , and the lead-out interconnection  134  that is constituted by the second conductive film  130 . According to this, it is possible to improve connection reliability between the first electrode  112  and the lead-out interconnection  134 . In addition, it is possible to improve operation reliability of the light-emitting device  10 . 
     Second Embodiment 
       FIG. 8  is a plan view illustrating a light-emitting device  12  according to a second embodiment, and corresponds to  FIG. 1  according to the first embodiment.  FIG. 9  is a cross-sectional view taken along line C-C in  FIG. 8 , and  FIG. 10  is a cross-sectional view taken along line D-D in  FIG. 8 .  FIG. 11  is a view illustrating a part of the light-emitting device  12  illustrated in  FIG. 8 . Particularly,  FIG. 11  illustrates a positional relationship between the first conductive film  110  and the second conductive film  130 . 
     In this embodiment, the first conductive film  110  of the joining structure  200  constitutes, for example, an electrode that constitutes the organic EL element. The second conductive film  130  of the joining structure  200  constitutes, for example, a lead-out interconnection that is electrically connected to an electrode that constitutes the organic EL element. In this case, the joining structure  200  is formed between the electrode that constitutes the organic EL element and the lead-out interconnection. At this time, a transition region, in which a transparent conductive material and a metal material are mixed, is formed between the electrode that constitutes the organic EL element, and the lead-out interconnection. 
     The light-emitting device  12  according to this embodiment has the same configuration as that of the light-emitting device  10  according to the first embodiment except for the configuration of a first electrode  112  and a lead-out interconnection  134 . 
     The light-emitting device  12  includes the joining structure  200 . The light-emitting device  12  includes the organic EL element  20  and the lead-out interconnection  134 . The organic EL element  20  includes the first electrode  112  that is constituted by the first conductive film  110 , the second electrode  152 , and the organic layer  140  that is disposed between the first electrode  112  and the second electrode  152 . The lead-out interconnection  134  is joined to the first electrode  112 , and is constituted by the second conductive film  130 . 
     Hereinafter, description will be given of an example of a configuration of the light-emitting device  12 . 
     In this embodiment, for example, the first electrode  112  is disposed on the substrate  100  in a matrix shape in a pixel region  300 . A plurality of the first electrodes  112 , which are disposed in a matrix shape, are spaced away from each other. Further, the pixel region  300  is a region including a plurality of the organic EL elements  20 . In an example illustrated in  FIG. 8 , a region surrounded by a one-dot chain line corresponds to the pixel region  300 . 
     The first electrode  112  is constituted by the first conductive film  110  that is constituted by a transparent conductive material. According to this, the first electrode  112  can have transparency. 
     The light-emitting device  12  according to this embodiment is not provided with the first interconnection  114  that constitutes the light-emitting device  10  according to the first embodiment. 
     In this embodiment, a case where the lead-out interconnection  134  is connected to the first electrode  112  is exemplified. The lead-out interconnection  134  extends in the Y-direction in the drawing. In addition, a plurality of the lead-out interconnections  134 , which are arranged in the X-direction in the drawing so as to be spaced away from each other, are provided on the substrate  100 . Each of the lead-out interconnection  134  is connected to each of a plurality of the first electrodes  112  which are arranged in the Y-direction. According to this, each of the plurality of first electrodes  112  is connected to the outside through each of the lead-out interconnections  134 . A signal for light-emission or non-light-emission is supplied to the organic EL element  20  through the lead-out interconnection  134 . 
     In this embodiment, the lead-out interconnection  134  is constituted by the second conductive film  130  that is constituted by a metal material. According to this, the first electrode  112  that is constituted by the first conductive film  110 , and the lead-out interconnection  134  that is constituted by the second conductive film  130  are joined to each other, thereby forming the joining structure  200 . In an example illustrated in  FIG. 11 , the joining structure  200  is formed at a portion surrounded by a broken line. 
     The first electrode  112  is connected to the lead-out interconnection  134  at one end thereof. At this time, for example, the first electrode  112  is joined to the lead-out interconnection  134  at one end thereof, thereby forming the joining structure  200 . As illustrated in  FIG. 10 , for example, a portion of the lead-out interconnection  134 , which is joined to the first electrode  112 , is located in a region in which the organic EL element  20  is formed when seen in a plan view. 
     The first electrode  112  extends in a second direction when seen from the lead-out interconnection  134 . Further, the second direction in this embodiment represents, for example, the X-direction in the drawing. The shape of the first electrode  112  is not particularly limited, and can be appropriately selected in combination with the design of the organic EL element  20 . Examples of the shape include a rectangular shape. 
     The lead-out interconnection  134  is provided in such a manner that at least a part thereof overlaps the first electrode  112 . At this time, for example, in a stacking region in which the first electrode  112  that is constituted by the first conductive film  110  and the lead-out interconnection  134  that is constituted by the second conductive film  130  are stacked on each other, the transition region, in which the transparent conductive material and the metal material are mixed, is formed. In addition, the joining structure  200 , in which the first conductive film  110  and the second conductive film  130  are joined to each other, includes the stacking region. 
     In an example illustrated in  FIG. 11 , the first electrode  112  is formed in such a manner that one end of the first electrode  112  overlaps a part of the lead-out interconnection  134 , and thus the stacking region is formed. In this case, for example, the first electrode  112  is formed to cover a part of each of an upper surface and a lateral surface of the lead-out interconnection  134 . 
     For example, the insulating layer  120  is formed to cover the lead-out interconnection  134 . In this embodiment, for example, the insulating layer  120  is provided to cover a part of each of the lead-out interconnection  134  and a lead-out interconnection  164 . In addition, as illustrated in  FIG. 11 , a plurality of first openings  122  are formed in the insulating layer  120  so as to constitute, for example, a matrix. 
     In this embodiment, the first electrode  112  is formed in the first opening  122 . According to this, a plurality of the first electrodes  112 , which are arranged in a matrix shape, are formed on the substrate  100 . In addition, as illustrated in  FIGS. 9 and 10 , the plurality of first electrodes  112  are spaced away from each other by the insulating layer  120 . For example, the first openings  122  are formed to overlap a part of the lead-out interconnection  134  when seen in a plan view. In this case, a part of the lead-out interconnection  134 , which overlaps the first openings  122  when seen in a plan view, is connected to the first electrode  112  that is formed in the first opening  122 . 
     For example, the insulating layer  120  is constituted by the same material as in the first embodiment. 
     For example, the partition wall  170 , the organic layer  140 , the second electrode  152 , the second interconnection  154 , and the lead-out interconnection  164  in this embodiment have the same configurations as those in the first embodiment. 
     As described above, even in this embodiment, it is possible to improve connection reliability between the first conductive film  110  and the second conductive film  130 , similar to the first embodiment. 
     In addition, according to this embodiment, it is possible to realize the light-emitting device  12  including the first electrode  112  that is constituted by the first conductive film  110 , and the lead-out interconnection  134  that is constituted by the second conductive film  130 . According to this, it is possible to improve connection reliability between the first electrode  112  and the lead-out interconnection  134 . In addition, it is possible to improve operation reliability of the light-emitting device  12 . 
     Third Embodiment 
       FIG. 12  is a plan view illustrating a configuration of a light-emitting device  10  according to a third embodiment. In this embodiment, for example, the light-emitting device  10  is used as a light source of an illuminating device and the like. According to this, the light-emitting device  10  includes one of each of a terminal (end of the lead-out interconnection  134 ) that is connected to the first electrode  112 , and a terminal (end of the lead-out interconnection  166 ) that is connected to the second electrode  152 . In addition, the light-emitting device  10  may include one piece of the organic EL element  20 , or may include a plurality of the organic EL elements  20 . In the latter case, a current simultaneously flows, and thus the plurality of organic EL elements  20  are simultaneously controlled. Further, in any case, the insulating layer  120  (not illustrated in the drawing) surrounds the organic EL element  20  so as to define a region serving as the organic EL element  20 . 
     A connection portion between the lead-out interconnection  134  and the first interconnection  114  is constituted by the joining structure  200  illustrated in the first embodiment. In addition, the lead-out interconnection  166  has the same configuration as that of the lead-out interconnection  134 . The lead-out interconnections  134  and  166  have a configuration in which a plurality of conductive layers are stacked. In this case, for example, the lead-out interconnections  134  and  166  have a configuration in which a first layer formed from Mo or a Mo alloy, a second layer formed from Al or an Al alloy, and a third layer formed from Mo or a Mo alloy are stacked in this order. 
     Next, description will be given of a method of manufacturing the light-emitting device  10  according to this embodiment. First, the lead-out interconnections  134  and  166  are formed on the substrate  100 . The lead-out interconnections  134  and  166  are formed by using a sputtering method or a deposition method. Subsequently, the first conductive film  110  is formed. A method of forming the first conductive film  110  is the same as in the first embodiment. At this time, the joining structure  200  is also formed. Subsequently, the insulating layer  120 , the organic layer  140 , and the conductive film  150  are formed. 
     Further, the conductive film  150  may be formed by the same method as in the first embodiment, or may be formed by the same method as in the first conductive film  110 . In the latter case, a connection portion between the conductive film  150  and the lead-out interconnection  166  also becomes the joining structure  200 . In this case, the conductive film  150  corresponds to the first conductive film, and the lead-out interconnection  166  corresponds to the second conductive film. 
     Also in this embodiment, since the joining structure  200  is formed between the lead-out interconnection  134  and the first interconnection  114 , connection reliability between the lead-out interconnection  134  and the first interconnection  114  is improved. In addition, in a case of forming the conductive film  150  by the same method as in the first conductive film  110 , the connection portion between the conductive film  150  and the lead-out interconnection  166  also becomes the joining structure  200 , and thus connection reliability between the conductive film  150  and the lead-out interconnection  166  is also improved. 
     Fourth Embodiment 
       FIG. 13  is a cross-sectional view illustrating a configuration of an optical device  11  according to a fourth embodiment. The optical device  11  according to this embodiment is a liquid crystal device, and has a configuration in which a liquid crystal material  420  is interposed between a substrate  402  and a substrate  404 . 
     Specifically, a first electrode  412  is formed on a surface of the substrate  402  which faces the substrate  404 , and a second electrode  414  is formed on a surface of the substrate  404  which faces the substrate  402 . The first electrode  412  and the second electrode  414  are formed from a transparent conductive material. In addition, a sealing member  406  is provided between the substrate  402  and the substrate  404  so as to surround a space that is filled with the liquid crystal material  420 . In other words, the substrate  402  and the substrate  404  are fixed to each other by the sealing member  406 . In addition, a space surrounded by the substrates  402  and  404 , and the sealing member  406  is filled with the liquid crystal material  420 . 
       FIG. 14  is a plan view of the optical device  11 . In FIG.  14 , the substrate  404  and the second electrode  414  are not illustrated for ease of explanation. 
     As illustrated in  FIG. 14 , a plurality of the first electrodes  412  extend on the substrate  402  in parallel with each other. Ends of the plurality of first electrodes  412  are located on an outer side of the sealing member  406 , and are respectively connected to different ones of terminals  432 . A connection portion between each of the first electrodes  412  and each of the terminals  432  is constituted by the joining structure  200 . 
     Further, a plurality of the second electrodes  414  extend on the substrate  404  in a direction that intersects (for example, a direction that is perpendicular to) the first electrodes  412 . In addition, a terminal that is connected to each of the second electrodes  414  is formed on the substrate  404 . A connection portion between this terminal and the second electrode  414  is also constituted by the joining structure  200 . 
     According to this embodiment, since the joining structure  200  is also formed between the first electrode  412  and the terminal  432 , and between the second electrode  414  and the terminal that is connected to the second electrode  414 , connection reliability therebetween is improved. 
     Hereinafter, the embodiments will be described in detail with reference to Examples. Further, the embodiments are not limited to the description in Examples. 
     Example 1 
     First, an ink containing silver particles was applied onto a glass substrate in a linear shape by an ink-jet method, thereby forming the second conductive film. Subsequently, a coating solution containing a transparent conductive material was applied in a linear shape and the coating solution was dried, thereby forming the first conductive film. At this time, the coating solution containing the transparent conductive material was applied in such a manner that the first conductive film covered a part of the second conductive film. As the coating solution containing the transparent conductive material, a solution, which was obtained by dispersing poly(3,4-ethylenedioxythiophene)/polystyrene sulfonate (PEDOT-PSS, CLEVIOS PH510 (manufactured by Heraeus Holding)) in a solvent, was used. Subsequently, a heat treatment was carried out with respect to the first conductive film and the second conductive film under conditions of 200° C. and 2 minutes, whereby the second conductive film was sintered, and the first conductive film was dried. According to this, a structure including the first conductive film and the second conductive film was prepared. 
     The structure, which was obtained in this manner, was applied to the light-emitting device according to the first embodiment. 
     In Example 1, a transition region, in which the transparent conductive material and the metal material are mixed, was formed between the first conductive film and the second conductive film. At this time, a linked body of metal particles, which extended in a dentritic shape, was observed on a surface of the second conductive film. In addition, the metal material, which was separated and dispersed from the second conductive film, was observed at the inside of the first conductive film. 
     In Example 1, when a current was allowed to flow between the first conductive film and the second conductive film for a long period of time, connection reliability between the first conductive film and the second conductive film was excellent. 
     Comparative Example 1 
     First, a transparent conductive film formed from ITO was formed on the glass substrate by a sputtering method. Subsequently, the transparent conductive film was patterned in a linear shape through dry-etching, thereby forming the first conductive film. Subsequently, a metal film formed from silver was formed on the first conductive film by using the sputtering method. Subsequently, the metal film was patterned in a linear shape through dry-etching, thereby forming the second conductive film on the first conductive film. According to this, a structure including the first conductive film and the second conductive film was prepared. 
     In Comparative Example 1, the transition region, in which the transparent conductive material and the metal material were mixed, was not formed between the first conductive film and the second conductive film. In Comparative Example 1, when a current was allowed to flow between the first conductive film and the second conductive film for a long period of time, the connection reliability between the first conductive film and the second conductive film was inferior to the connection reliability in Example 1. 
     Example 2 
     In Example 2, a structure including the first conductive film and the second conductive film was obtained in the same manner as in Example 1 except that as the substrate, a film-shaped substrate constituted by a biaxial stretched polyethylene terephthalate (PET) was used. In addition, the structure that was obtained is applicable to the light-emitting device according to the first embodiment. 
     Also in Example 2, the transition region, in which the transparent conductive material and the metal material were mixed, was formed between the first conductive film and the second conductive film. According to this, it can be seen that Example 2 is excellent in the connection reliability between the first conductive film and the second conductive film. 
     Hereinbefore, embodiments and Examples have been described with reference to the accompanying drawings. However, these are illustrative only, and various configurations other than embodiments and Examples can be employed. 
     Priority is claimed on Japanese Patent Application No. 2013-75996, filed Apr. 1, 2013, the content of which is incorporated herein by reference.