Patent Publication Number: US-2019198804-A1

Title: Organic el display device

Description:
TECHNICAL FIELD 
     The present invention relates to an organic EL display device. 
     BACKGROUND ART 
     In recent years, as a display device, an organic EL display device which uses an organic electro-luminescence (EL) material as a light-emitting substance is in the spotlight. An organic EL element which is constituted by interposing the organic EL material between a pair of electrodes is likely to be influenced by moisture. For example, deterioration such as oxidation or peeling of the electrode may be generated due to sticking of water. Therefore, a countermeasure against water permeating an area in which the organic EL element is disposed is provided with the organic EL display device. 
     For example, Patent Literature 1 discloses an organic EL element having a so-called hollow sealing structure. In Patent Literature 1, a water catching agent (drying agent) is disposed in a space (sealed space) which is sealed by an element substrate and a sealing substrate. Patent Literature 2 discloses an organic EL element having a so-called filling and sealing structure. In Patent Literature 2, the sealed space described above is filled with a filler into which a drying agent is dispersed. 
     CITATION LIST 
     Patent Literature 
     [Patent Literature 1] Japanese Unexamined Patent Publication No. 2012-038659 
     [Patent Literature 2] Japanese Unexamined Patent Publication No. 2014-201574 
     SUMMARY OF INVENTION 
     Technical Problem 
     In an organic EL display device having a hollow sealing structure as Patent Literature 1 described above, an area in which an inert gas is sealed is disposed, in addition to an area for disposing a water catching agent, in a sealed space. In such an organic EL display device, a difference between a refractive index of the area in which the inert gas is sealed and a refractive index of an element substrate and a sealing substrate is large. Therefore, in a case where light is extracted from the sealing substrate side of the organic EL display device, light-extracting efficiency tends to be low. On the contrary, in an organic EL display device having a filling and sealing structure as Patent Literature 2 described above, a refractive index of a filler is adjusted, thereby, it is possible to improve light-extracting efficiency in comparison with the organic EL display device having the hollow sealing structure. 
     However, in the organic EL display device having the filling and sealing structure, a deterioration degree of an organic EL element tends to vary in accordance with a position at which the organic EL element is disposed, in comparison with the hollow sealing structure. For example, the closer the organic EL element which is positioned close to an edge of the element substrate or the sealing substrate, the more the organic EL element tends to easily deteriorate. Therefore, in the organic EL display device, both of improvement in light-extracting efficiency and uniformity in deterioration of the organic EL element are desired. 
     An object of an aspect of the present invention is to provide an organic EL display device that is capable of improving light-extracting efficiency, and is capable of preventing local deterioration. 
     Solution to Problem 
     According to an aspect of the present invention, an organic EL display device includes: a first substrate that has a first main surface; frame-shaped sealing layer that is in contact with the first main surface, and is disposed along an edge of the first substrate; a second substrate that is in contact with the sealing layer, and has a second main surface facing the first main surface; an organic EL element part on the second main surface wherein the organic EL element part is disposed in a sealed space which is sealed by being surrounded with the first substrate, the sealing layer, and the second substrate; and a filler with which at least an area overlapping the organic EL element part in a layer-stacked direction of the first substrate and the second substrate is filled, in the sealed space. A void is disposed in the sealed space that is positioned between an inner side wall of the sealing layer and a portion which is closest to the inner side wall in the organic EL element part. 
     In the organic EL display device, at least the area overlapping the organic EL element part in the layer-stacked direction is filled with the filler in the sealed space. Therefore, a refractive index of the filler is adjusted, and reflection in the sealed space is reduced, thereby, the organic EL display device can improve light-extracting efficiency in comparison with an organic EL display device having a hollow sealing structure. In addition, the void is disposed in the sealed space that is positioned between the inner side wall of the sealing layer and the portion which is closest to the inner side wall in the organic EL element part. Thereby, water permeating toward a portion which is most likely to be influenced by the water in the organic EL element part from the edge of the first substrate and the sealing layer diffuses into the above-described void of the sealed space. Accordingly, since it is possible to prevent the water which permeates the sealed space from directly permeating the above-described portion of the organic EL element part, it is possible to prevent local deterioration of the organic EL element part. 
     According to another aspect of the present invention, an organic EL display device includes: a first substrate that has a first main surface; a frame-shaped sealing layer that is in contact with the first main surface and is disposed along an edge of the first substrate; a second substrate that is in contact with the sealing layer, and has a second main surface facing the first main surface; an organic EL element part on the second main surface wherein the organic EL element part is disposed in a sealed space which is sealed by being surrounded with the first substrate, the sealing layer, and the second substrate; and a filler with which at least an area overlapping the organic EL element part in a layer-stacked direction of the first substrate and the second substrate is filled, in the sealed space, in which a void is disposed in the sealed space that is positioned between the edge of the first substrate and a portion which is closest to the edge in the organic EL element part. 
     In the organic EL display device, at least the area overlapping the organic EL element part in the layer-stacked direction is filled with the filler in the sealed space. Therefore, the refractive index of the filler is adjusted, and the reflection in the sealed space is reduced, thereby, the organic EL display device can improve the light-extracting efficiency in comparison with the organic EL display device having the hollow sealing structure. In addition, the void is disposed in the sealed space that is positioned between the edge of the first substrate and the portion which is closest to the edge in the organic EL element part. Thereby, the water permeating toward the portion which is most likely to be influenced by the water in the organic EL element part from the edge of the first substrate and the sealing layer diffuses into the above-described void of the sealed space. Accordingly, since it is possible to prevent the water which permeates the sealed space from directly permeating the above-described portion of the organic EL element part, it is possible to prevent the local deterioration of the organic EL element part. 
     When viewed in the layer-stacked direction, a corner part may be disposed in the sealing layer, and the void may be disposed between the corner part of the sealing layer and the filler. In this case, since the water tends to permeate the sealed space in the vicinity of the corner part of the sealing layer from a plurality of directions, the organic EL element part which is disposed close to the corner part is likely to be influenced by the water. Therefore, the void is disposed between the corner part and the filler, thereby, it is possible to prevent the local deterioration of the organic EL element part that is positioned close to the corner part. 
     When viewed in the layer-stacked direction, the void may be disposed so as to surround the organic EL element part in the sealed space. In this case, since the water which permeates the sealed space firstly diffuses into the whole of the void, it is possible to suitably prevent the water from locally permeating the organic EL element part. 
     On the first main surface, a groove may be disposed on an outside of the organic EL element part and in the sealed space, and the void may be disposed in at least a portion of the sealed space overlapping the groove. In this manner, the groove is disposed, thereby, the filler is prevented from spreading to the sealing layer, and it is possible to easily dispose the void in the sealed space. 
     The groove may have a frame shape which surrounds the organic EL element part when viewed in the layer-stacked direction. In this case, the filler is prevented from spreading in the sealed space by the groove, thereby, it is possible to easily dispose the void which surrounds the organic EL element part in the sealed space. 
     The groove may include a first groove having a frame shape which surrounds the organic EL element part when viewed in the layer-stacked direction, and a second groove having a frame shape which surrounds the first groove when viewed in the layer-stacked direction, and the void may be disposed in at least a portion of the sealed space overlapping the second groove. In this case, the filler is prevented from spreading in the sealed space by the first groove, and it is possible to reliably dispose the void overlapping the second groove in the sealed space. 
     The organic EL display device may further include a drying agent that is disposed in the sealed space, in which the drying agent may be disposed on at least a part of a surface which forms the void, in the filler. In this case, it is possible to suitably prevent the water which diffuses into the void from permeating a place that is likely to deteriorate in the organic EL element part. 
     The organic EL display device may further include a drying agent that is disposed in the groove, in which each of the first substrate, the second substrate, and the filler may have light-transmitting properties. In this case, it is possible to suitably prevent the water which diffuses into the void from permeating the place that is likely to deteriorate in the organic EL element part. In addition, since it is possible to make the organic EL display device into a see-through type display device, double-sided light emission of the organic EL display device becomes possible. 
     The drying agent that is disposed in the groove may have light-shielding properties. In this case, it is possible to prevent the local deterioration of the organic EL element part, without shielding the light which is output to the outside from the organic EL display device, due to the drying agent. Furthermore, the drying agent having light-shielding properties may include a calcium oxide. 
     A drying agent may be included in the filler. In this case, since the water which permeates into the sealed space is caught due to the drying agent, it is possible to suitably prevent the water from permeating the organic EL element part. 
     Advantageous Effects of Invention 
     According to the aspects of the present invention, an organic EL display device that is capable of realizing improvement in light-extracting efficiency, and prevention in local deterioration is provided. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       (a) of  FIG. 1  is a schematic plan view of an organic EL display device according to the present embodiment, and (b) of  FIG. 1  is a schematic sectional view taken along A-A line in (a) of  FIG. 1 . 
       (a) of  FIG. 2  is a schematic plan view illustrating a first substrate, and (b) of  FIG. 2  is a schematic sectional view taken along B-B line in (a) of  FIG. 2 . (a) to (c) of  FIG. 3  are schematic diagrams for describing a filling method of a filler. 
       (a) of  FIG. 4  is a schematic plan view of an organic EL display device according to Modification Example 1, and (b) of  FIG. 4  is a schematic sectional view taken along C-C line in (a) of  FIG. 4 . (a) of  FIG. 5  is a schematic plan view of an organic EL display device according to Modification Example 2, and (b) of  FIG. 5  is a schematic sectional view taken along D-D line in (a) of  FIG. 5 . 
       (a) of  FIG. 6  is a schematic plan view of a first substrate according to Modification Example 3, (b) of  FIG. 6  is a schematic sectional view taken along E-E line in (a) of  FIG. 6 , and (c) of  FIG. 6  is a schematic sectional view of a state of being filled with a filler in Modification Example 3. 
         FIG. 7  is a schematic plan view of an organic EL display device according to Modification Example 4. 
       (a) of  FIG. 8  is a schematic plan view illustrating a light-emitting element for a test, and (b) of  FIG. 8  is a schematic sectional view taken along F-F line in (a) of  FIG. 8 . 
         FIG. 9  is a graph illustrating light-emitting area changes in Examples 1 and 2, and Comparative Example. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Hereinafter, suitable embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same signs are used for the same components, or components having the same function, and the repeated description thereof will be omitted. 
     A configuration of an organic EL display device according to the present embodiment will be described with reference to  FIG. 1 . (a) of  FIG. 1  is a schematic plan view of the organic EL display device according to the present embodiment, and (b) of  FIG. 1  is a schematic sectional view taken along A-A line in (a) of  FIG. 1 . 
     As illustrated in (a) and (b) of  FIG. 1 , an organic EL display device  1  according to the present embodiment is a passive matrix type, and is a see-through type display device. Therefore, in the organic EL display device  1 , double-sided light emission becomes possible. The organic EL display device  1  includes a first substrate  2  and a second substrate  3  which are stacked on each other, an organic EL element part  4 , wiring portions  5   a  to  5   d,  a sealing layer  6 , a filler  7 , an integrated circuit  8 , and an FPC  9  (flexible printed circuit board). Hereinafter, a direction in which the first substrate  2  and the second substrate  3  are stacked on each other will be simply described as a “layer-stacked direction.” 
     (a) of  FIG. 2  is a schematic plan view illustrating the first substrate, and (b) of  FIG. 2  is a schematic sectional view taken along B-B line in (a) of  FIG. 2 . As illustrated in (a) and (b) of  FIG. 2  in addition to  FIG. 1 , the first substrate  2  is a substrate which functions as a sealing substrate, and is disposed to face the second substrate  3 . For example, the first substrate  2  is a glass substrate, or a substrate (for example, a plastic substrate or the like) having flexibility, and has light-transmitting properties. A main surface  2   a  (first main surface) facing the second substrate  3  in the first substrate  2  has a substantially rectangular shape. On the main surface  2   a,  a groove  2   b  having a quadrangular frame shape is disposed, when viewed in the layer-stacked direction. For example, a width W 1  of the groove  2   b  is 0.2 to 2 mm. For example, a depth of the groove  2   b  is 50 μm or more, and is a half or less of a thickness of the first substrate  2 . 
     In the main surface  2   a,  an edge area  2   d  on an edge  2   c  side in comparison with the groove  2   b  is an area on which the sealing layer  6  is disposed. In the same manner as the groove  2   b,  the edge area  2   d  has a quadrangular frame shape when viewed in the layer-stacked direction. For example, a width W 2  of the edge area  2   d  is approximately 1 to 2 mm. 
     The second substrate  3  is an element substrate on which the organic EL element part  4 , and the wiring portions  5   a  to  5   d  are disposed. In the same manner as the first substrate  2 , for example, the second substrate  3  is a glass substrate, or a substrate (for example, a plastic substrate or the like) having flexibility, and has light-transmitting properties. In the same manner as the main surface  2   a,  a main surface  3   a  (second main surface) of the second substrate  3  has a substantially rectangular shape. A short side of the main surface  3   a  is substantially the same as the short side of the main surface  2   a,  and a long side of the main surface  3   a  is longer than the long side of the main surface  2   a.  Therefore, in a case where the short sides of the main surfaces  2   a  and  3   a  are combined, a part of the main surface  3   a  is exposed from the first substrate  2 . For example, a distance between the main surfaces  2   a  and  3   a  in the layer-stacked direction is 10 to 30 μm. In the present embodiment, “substantially the same” is a concept which does not indicate entirely the same, but includes a few errors (for example, several % at the maximum). 
     The organic EL element part  4  is a portion in which an electric current is supplied to generate light, and is disposed on the main surface  3   a  of the second substrate  3 . The organic EL element part  4  is disposed to be surrounded with the groove  2   b  of the first substrate  2  when viewed in the layer-stacked direction, in a sealed space S which is sealed by being surrounded with the first substrate  2 , the second substrate  3 , and the sealing layer  6 . In other words, when viewed in the layer-stacked direction, the groove  2   b  is disposed on an outside of the organic EL element part  4  in the sealed space S, and the groove  2   b  has a frame shape which surrounds the organic EL element part  4 . In the organic EL element part  4 , a plurality of organic EL elements  11  which are arranged in a matrix, and a cathode separation layer (not illustrated) of which a cross section has a reverse tapered shape are disposed. 
     For example, each organic EL element  11  is a light-emitting element that has an anode, a cathode, and an organic light-emitting layer which is interposed between the anode and the cathode. For example, an anode is formed on the main surface  3   a  of the second substrate  3 , and an organic light-emitting layer and a cathode are formed in sequence on the anode. For example, as a material which forms the anode, a material such as ITO (indium tin oxide) or IZO (indium zinc oxide) having light-transmitting properties is used. The organic light-emitting layer may have an electron injection layer, an electron transport layer, a hole transport layer, a hole injection layer, and the like, in addition to a light-emitting layer including a light-emitting material. The light-emitting material may be a low molecular organic compound, or may be a high molecular organic compound. As a light-emitting material, a fluorescent material may be used, or a phosphorescent material may be used. For example, as a material (conductive material) of a conductive layer which forms the cathode, aluminum, silver, alkaline earth metal (such as magnesium or calcium), or a material such as IZO (indium zinc oxide) or ITO (indium tin oxide) having light-transmitting properties is used. In a case where the light is output to the first substrate  2  side, the cathode is set to be formed in thickness having light-transmitting properties. 
     The wiring portions  5   a  to  5   d  are portions in which a plurality of lead wires are disposed. Each of the wiring portions  5   a,    5   b,  and  5   c  is wires that connect the organic EL element part  4  and the integrated circuit  8 . The wiring portion  5   d  is wires that connect the integrated circuit  8  and the FPC  9 . At least one of the wiring portions  5   a  to  5   d  may be formed at the same time as the anode or the cathode of the organic EL element  11 . The lead wires which are included in the wiring portions  5   a  to  5   d  is formed of single metal layer, or a stacked metal layer. On a surface of the lead wire, for example, a barrier film such as a silicon oxide film or a silicon nitride film may be disposed. 
     The sealing layer  6  functions as a bonding agent for bonding the first substrate  2  and the second substrate  3 , and functions as a side wall for forming the sealed space S. The sealing layer  6  is disposed along the edge area  2   d  on the main surface  2   a  of the first substrate  2 , and is in contact with the edge area  2   d  and the main surface  3   a  of the second substrate  3 . Therefore, the width of the sealing layer  6  is stably formed in accordance with the edge area  2   d.  The sealing layer  6  is in contact with a part of the lead wires which form the wiring portions  5   a  to  5   c.  The sealing layer  6  has a quadrangular frame shape along the shape of the edge area  2   d  when viewed in the layer-stacked direction. Therefore, the sealing layer  6  is provided with four corner parts  6   a  to  6   d  when viewed in the layer-stacked direction. Each of the corner parts  6   a  to  6   d  of the sealing layer  6  includes a portion which forms a corresponding internal corner in the sealing layer  6  when viewed in the layer-stacked direction, and a vicinity of the portion. For example, the sealing layer  6  includes an ultraviolet ray curable resin having adhesive properties. The sealing layer  6  may include a spacer such as a silica particle. 
     The filler  7  is accommodated in the sealed space S, and buries a space in the sealed space S. All of the sealed space S is not filled with the filler  7 , and is disposed to bury, for example, approximately 10 to 90% (or approximately 70 to 90%) of the sealed space S. At least an area overlapping the organic EL element part  4  in the layer-stacked direction is filled with the filler  7 , in the sealed space S. In addition, the filler  7  is disposed in an area not overlapping the organic EL element part  4  in the sealed space S, and buries a part of the groove  2   b.  In the present embodiment, the filler  7  is disposed to bury most (approximately 90%) of the sealed space S. 
     As a filler  7 , for example, a liquid-shaped material or a gel-shaped material having light-transmitting properties is used. Visible ray light transmittance of the filler  7  may be 80% or more. As a base material of the filler  7 , for example, various curable resins may be used, from the viewpoint of easiness of viscosity adjustment. The filler  7  may include a drying agent having light-transmitting properties. In this case, the visible ray light transmittance of the filler  7  may be 80% or more. Thereby, it is possible to prevent the light which is output to the first substrate  2  side from being shielded while favorably preventing water from permeating the organic EL element part  4  by the drying agent. From the viewpoints of water catching performance, visible light light-transmitting properties, and easiness of viscosity adjustment, a liquid-shaped drying agent which includes a metal alkoxide as a water catching component may be used. The filler  7  may be in a state in which the materials described above are cured. 
     A void V is disposed in an area which is not filled with the filler  7  in the sealed space S. The void V is provided by separating the sealing layer  6  and the filler  7  from each other, and is formed from, for example, the main surface  2   a  of the first substrate  2 , the main surface  3   a  of the second substrate  3 , an inner side wall  6   e  of the sealing layer  6 , and the surface of the filler  7 . 
     In the present embodiment, the void V is disposed at least in the sealed space S that is positioned between the inner side wall  6   e  of the sealing layer  6  and a portion which is closest to the inner side wall  6   e  in the organic EL element part  4 . The portion which is closest to the inner side wall  6   e  in the organic EL element part  4  includes an end side  4   a  of the organic EL element part  4 , the end side  4   a  being located on a side that is opposite to a side on which the integrated circuit  8  is mounted. More specifically, the portion which is closest to the inner side wall  6   e  in the organic EL element part  4  is each end side which forms the organic EL element part  4 . In a case where a plurality of portions which are closest to the inner side wall  6   e  are present in the organic EL element part  4 , and are separated from each other, the void V may be disposed by corresponding to at least one of the above-described portions, and may be disposed by corresponding to all of the above-described portions. In other words, one void V may be disposed in the sealed space S, or a plurality of voids V may be disposed in the sealed space S. The void V is disposed in a part of the groove  2   b,  and a portion of the sealed space S overlapping the groove  2   b.  The void V may be disposed between at least one of the corner parts  6   a  to  6   d  of the sealing layer  6  and the filler  7 . 
     In the present embodiment, the void V is disposed to surround the organic EL element part  4  in the sealed space S when viewed in the layer-stacked direction. Therefore, in the present embodiment, the void V is disposed in both of the sealed space S that is positioned between the inner side wall  6   e  of the sealing layer  6  and the portion which is closest to the inner side wall  6   e  in the organic EL element part  4 , and the sealed space S between the corner parts  6   a  to  6   d  of the sealing layer  6  and the filler  7 . 
     The integrated circuit  8  is a driver circuit that controls light emission and non-light emission of each organic EL element  11 . The integrated circuit  8  is mounted in the area which is exposed from the first substrate  2  on the main surface  3   a  of the second substrate  3 , and is connected to the wiring portions  5   a  to  5   d.  For example, the integrated circuit  8  is an IC chip or the like. The number of the integrated circuits  8  which are mounted on the main surface  3   a  may be one, or may be plural. 
     The FPC  9  is connected to the wiring portion  5   d,  and is wires which connect the organic EL display device  1  and an external device. For example, the FPC  9  is formed using a plastic substrate having flexibility. For example, the external device which is connected to the FPC  9  is a power source, an electric current control circuit, and the like. 
     Next, an example of a filling method of the filler  7  using ODF (One Drop Filling) method will be described with reference to (a) to (c) of  FIG. 3 . (a) to (c) of  FIG. 3  are schematic diagrams for describing the filling method of the filler. In the description of the filling method, the organic EL element part  4  and the wiring portions  5   a  to  5   d  are omitted. 
     First, as illustrated in (a) of  FIG. 3 , the first substrate  2  with an adhesive  12  is prepared, the adhesive  12  becoming the sealing layer  6  and being disposed on the edge area  2   d.  Next, the filler  7  is dropped onto the main surface  2   a  of the first substrate  2 . A dropping amount of the filler  7  is adjusted such that the void V is made in the sealed space S later. A place at which the filler  7  is dropped on the main surface  2   a  may be one place, or may be a plurality of places. 
     Next, as illustrated in (b) of  FIG. 3 , in a low pressure state or a vacuum state, the first substrate  2  is sealed by being overlapped with the second substrate  3 . At this time, a pressure is applied to each of the first substrate  2  and the second substrate  3 , and an interval between the first substrate  2  and the second substrate  3  in the layer-stacked direction is narrowed. At this time, the filler  7  in the sealed space S spreads to the adhesive  12  side, while burying the void between the second substrate  3  and the filler  7 . Therefore, as illustrated in (c) of  FIG. 3 , a part of the filler  7  intrudes the groove  2   b,  thereby, spreading of the filler  7  is stopped. Thereby, the void V is formed. After the second substrate  3  is stuck to the first substrate  2 , the adhesive  12  is irradiated with an ultraviolet ray in a normal pressure state, and heating is performed onto the adhesive  12 , thereby, the sealing layer  6  is formed. 
     In such an organic EL display device  1  according to the embodiment, the void V is disposed in the sealed space S by separating the sealing layer  6  and the filler  7  from each other. The void V is disposed at least in the sealed space S that is positioned between the inner side wall  6   e  of the sealing layer  6  and the portion which is closest to the inner side wall  6   e  in the organic EL element part  4 . Thereby, the water permeating toward the above-described portion which is most likely to be influenced by the water in the organic EL element part  4 , from the inner side wall  6   e  of the sealing layer  6 , diffuses into the void V in the sealed space S. Accordingly, since it is possible to prevent the water which permeates the sealed space S from directly permeating the above-described portion of the organic EL element part  4 , and it is possible to prevent a dark spot or shrinkage from being generated in the portion, it is possible to prevent local deterioration of the organic EL element part  4 . 
     In addition, in the organic EL display device  1 , at least the area overlapping the organic EL element part  4  in the layer-stacked direction is filled with the filler  7  in the sealed space S. Therefore, a refractive index of the filler  7  is adjusted, and for example, the refractive index thereof is made substantially the same as the refractive index with the first substrate  2 . Thereby, the light is less likely to be reflected at an interface between the filler  7  and the first substrate  2 . In other words, it is possible to reduce the number of reflection interfaces in the organic EL display device  1 . Thereby, according to the organic EL display device  1 , it is possible to improve light-extracting efficiency in comparison with an organic EL display device having a hollow sealing structure. 
     When viewed in the layer-stacked direction, the corner parts  6   a  to  6   d  are disposed in the sealing layer  6 , and the voids V are disposed between the corner parts  6   a  to  6   d  of the sealing layer  6  and the filler  7 . Since the water tends to permeate the sealed spaces S in the vicinity of the corner parts  6   a  to  6   d  of the sealing layer  6  from a plurality of directions, portions which are close to the corner parts  6   a  to  6   d  in the organic EL element part  4  are likely to be influenced by the water. Therefore, the voids V are respectively disposed between the corner parts  6   a  to  6   d  and the filler  7 , thereby, it is possible to cause the water permeating the sealed space S through the corner parts  6   a  to  6   d  to diffuse into the void V. Thereby, it is possible to prevent the local deterioration of the organic EL element part  4  which is positioned close to the corner parts  6   a  to  6   d.    
     When viewed in the layer-stacked direction, the void V is disposed to surround the organic EL element part  4  in the sealed space S. Therefore, the water permeating the sealed space S diffuses into the whole of the void V. Thereby, since an amount of the water permeating into the organic EL element part  4  becomes difficult to be biased toward a specific area, it is possible to suitably prevent the water from locally permeating into the organic EL element part  4 . 
     On the main surface  2   a,  the groove  2   b  is disposed on the outside of the organic EL element part  4  in the sealed space S, and the void V is disposed in at least a portion of the sealed space S overlapping the groove  2   b.  In this manner, the groove  2   b  is disposed, thereby, the filler  7  is prevented from spreading to the sealing layer  6 , and it is possible to easily dispose the void V in the sealed space S. 
     The groove  2   b  has a frame shape which surrounds the organic EL element part  4  when viewed in the layer-stacked direction. In this case, the filler  7  is prevented from spreading in the sealed space S by the groove  2   b,  thereby, it is possible to easily dispose the void V which surrounds the organic EL element part  4 , in the sealed space S. 
     The drying agent may be included in the filler  7 . In this case, it is possible to suitably prevent the water which permeates the sealed space S from reaching the organic EL element part  4 . In a case where the drying agent has light-transmitting properties, it is possible to prevent the light which is output to the first substrate  2  side from being shielded. 
     Hereinafter, Modification Examples of the embodiment described above will be described with reference to the drawings. In the following description of Modification Examples, the description of a portion which is repeated with the embodiment described above will be omitted. 
     (a) of  FIG. 4  is a schematic plan view of an organic EL display device according to Modification Example 1, and (b) of  FIG. 4  is a schematic sectional view taken along C-C line in (a) of  FIG. 4 . As illustrated in (a) and (b) of  FIG. 4 , in an organic EL display device  1 A according to Modification Example 1, the groove  2   b  is not disposed in a first substrate  2 A. Even in this case, the dropping amount and conditions on the filling method of the filler  7  are adjusted, thereby, it is possible to dispose the void V in the sealed space S. Even in such Modification Example 1, effects which are the same as those of the embodiment described above are accomplished. 
     (a) of  FIG. 5  is a schematic plan view of an organic EL display device according to Modification Example 2, and (b) of  FIG. 5  is a schematic sectional view taken along D-D line in (a) of  FIG. 5 . As illustrated in (a) and (b) of  FIG. 5 , in Modification Example 2, the groove  2   b  of a first substrate  2 B is filled with a drying agent  21 . The first substrate  2 B is used, and at least a part of the drying agent  21  is exposed from the filler  7 , thereby, at least a part of the surface which forms the void V is formed from the drying agent  21 . In such Modification Example 2, since the water which diffuses into the void V is caught by the drying agent  21 , it is possible to suitably prevent the water from permeating into the organic EL element part  4 . 
     In Modification Example 2, the drying agent  21  which is disposed in the groove  2   b  has light-shielding properties. In this case, the drying agent  21  contains oxide particles including an oxide of, for example, an alkaline earth metal. The oxide particles include the oxide of the alkaline earth metal that can have water catching performance. In the oxide particles, the oxide of the alkaline earth metal of 80 mass % or more, or 90 mass % or more is included. As an oxide of the alkaline earth metal, for example, a magnesium oxide (MgO), a calcium oxide (CaO), a strontium oxide (SrO), and a barium oxide (BaO) may be used. The oxide of the alkaline earth metal may be the magnesium oxide and/or the calcium oxide. Such a drying agent  21  is disposed in the groove  2   b  which surrounds the organic EL element part  4 , thereby, it is possible to suitably prevent the water from permeating into the organic EL element part  4 , without shielding the light which is output to the outside from the organic EL display device  1 A. It is possible to refer to the drying agent having light-shielding properties as a drying agent not having light-transmitting properties. 
     In Modification Example 2, the drying agent is included in the filler  7 , thereby, it is possible to more suitably prevent the deterioration of the organic EL element part  4 . The groove  2   b  is filled with the drying agent  21  to fully bury the groove  2   b,  but is not limited thereto. For example, the groove  2   b  may be filled with the drying agent  21  to bury approximately a half of the groove  2   b.  In this case, a part of the drying agent  21  may be covered with the filler  7 . 
     (a) of  FIG. 6  is a schematic plan view of a first substrate according to Modification Example 3, and (b) of  FIG. 6  is a schematic sectional view taken along E-E line in (a) of  FIG. 6 . As illustrated in (a) and (b) of  FIG. 6 , in Modification Example 3, the groove  2   b  which is disposed in the main surface  2   a  of a first substrate  2 C has two grooves  31   a  and  31   b.  The groove  31   a  (first groove) has a frame shape which surrounds the organic EL element part  4  when viewed in the layer-stacked direction, and the groove  31   b  (second groove) has a frame shape which surrounds the groove  31   a  when viewed in the layer-stacked direction. In other words, the groove  31   a  which surrounds the organic EL element part  4  is surrounded by the groove  31   b.  The groove  31   b  is positioned on an inside of the edge area  2   d.  A width W 3  of the groove  31   a  is smaller than a width W 4  of the groove  31   b,  but is not limited thereto. That is, the width W 3  may be equal to or more than the width W 4  or more. The depths of the grooves  31   a  and  31   b  are substantially the same, but may be different from each other. 
     (c) of  FIG. 6  is a schematic sectional view illustrating a state of being filled with the filler in Modification Example 3. As illustrated in (c) of  FIG. 6 , in a case where the sealed space S is filled with the filler  7  using the first substrate  2 C, the filler  7  is prevented from spreading to the sealing layer  6  by the groove  31   a.  Thereby, the filler  7  is less likely to reach up to the groove  31   b  beyond the groove  31   a,  and it is possible to reliably dispose the void V overlapping the groove  31   b  in the sealed space S. Accordingly, in Modification Example 3, it is possible to reliably dispose the void V of the frame shape in the sealed space S, in comparison with the embodiment described above and Modification Examples 1 and 2. In Modification Example 3, the filler  7  may enter the groove  31   b.    
       FIG. 7  is a schematic plan view of an organic EL display device according to Modification Example 4. As illustrated in  FIG. 7 , an organic EL display device  1 B in Modification Example 4 is a segment type display device, differently from the embodiment described above. Therefore, it is possible to freely set the shape of an organic EL element  11 A when viewed in the layer-stacked direction, in comparison with the embodiment described above. In Modification Example 4, the organic EL elements  11 A indicating a numeral, a character, or a figure when viewed in the layer-stacked direction are disposed in an organic EL element part  4 A. In such an organic EL display device  1 B, in a case where the drying agent is included in the filler  7 , a lot of fillers  7  may be disposed close to the organic EL element  11 A. In other words, the filler  7  may not spread uniformly in the sealed space. For example, in  FIG. 7 , most of the grooves  2   b  which are disposed close to the organic EL element  11 A is filled with the filler  7 . On the other hand, the groove  2   b  (groove  2   b  which is disposed on an upper right side of the organic EL element part  4 A on a sheet of  FIG. 7 ) to which the organic EL element  11 A is not disposed close is not filled with the filler  7 , in contrast to other places. In this manner, a large amount of the filler  7  in which the drying agent is included close to the organic EL element  11 A is disposed, thereby, it is possible to suitably catch the water which is to permeate the organic EL element  11 A, in addition to the effects which are the same as those of the embodiment described above. 
     The organic EL display device according to the present invention is not limited to the embodiment and Modification Examples described above, and various modifications are possible, in addition thereto. The embodiment described above and Modification Examples described above may be appropriately combined. For example, Modification Examples 2 and 3 may be combined. In this case, for example, the groove  31   b  may be filled with the drying agent  21 . 
     In the embodiment described above and Modification Examples 2 to 4, the shape of the groove which is disposed in the first substrate is not particularly limited. For example, the groove may not have the frame shape. The groove may be disposed to overlap the sealed space that is positioned between the edge of the first substrate and a portion which is closest to the edge in the organic EL element part. More specifically, the groove may be disposed to overlap the sealed space that is positioned between the inner side wall of the sealing layer and a portion which is closest to the inner side wall in the organic EL element part. 
     In the embodiment described above and Modification Examples described above, the void may not be disposed in the sealed space that is positioned between the inner side wall of the sealing layer and the portion which is closest to the inner side wall in the organic EL element part. For example, in a case where a variation in width of the sealing layer is largely generated, the void may be provided in the sealed space that is positioned between the edge of the first substrate and the portion which is closest to the edge in the organic EL element part. In addition, in the embodiment described above and Modification Examples described above, the void may be disposed in at least the sealed space that is positioned between the edge of the first substrate and the portion which is closest to the edge in the organic the EL element part, between the inner side wall of the sealing layer and the portion which is closest to the inner side wall in the organic EL element part. 
     In the embodiment described above and Modification Examples described above, the sealing layer and a part of the filler are in contact with each other, and other portions are separated from each other, thereby, the void may be disposed. In this case, the void may be defined by the main surface of the first substrate or the main surface of the second substrate, the inner side wall of the sealing layer, and the surface of the filler. In this case, the plurality of voids can be foiled due to a portion with which the sealing layer and the filler are in contact. 
     In the embodiment described above and Modification Examples 2 to 4, the void may not necessarily be disposed in the groove. If the void is disposed on the groove in the sealed space, all of the grooves may be filled with the filler. 
     In the embodiment described above and Modification Examples 2 to 4, in a case where the drying agent is at least a part of the surface which forms the void, the drying agent may not be disposed in the groove. For example, the drying agent may be disposed in at least one of the main surface of the first substrate, the main surface of the second substrate, the inner side wall of the sealing layer, and the surface of the filler. 
     In the embodiment described above and Modification Examples described above, the viscosity of the filler is not particularly limited, but may be a value that is capable of flowing at, for example, room temperature. In this case, the organic EL display device is included, thereby, the filler is capable of flowing in the void. In a case where the drying agent is included in the filler, it is possible to expose the drying agent which does not deteriorate on the surface of the void by the flowing of the filler. Thereby, it is possible to effectively catch the water which permeates the sealed space. 
     In the embodiment described above and Modification Examples described above, the organic EL display device is not limited to a passive matrix type display device. For example, the organic EL display device may be an active matrix type display device. In this case, a transistor or the like corresponding to each organic EL element is disposed. 
     In the embodiment described above and Modification Examples described above, the organic EL display device may not be a see-through type display device. For example, at least one of the first substrate and the filler may not have light-transmitting properties. 
     In the embodiment described above and Modification Examples described above, both of the first substrate and the second substrate are not limited to the substantially rectangular shapes when viewed in the layer-stacked direction. For example, both of the first substrate and the second substrate when viewed in the layer-stacked. direction may have polygonal shapes, or may have substantially circular shapes. In the same manner, the sealing layer which is disposed in the first substrate may have a polygonal frame shape, or may have a substantially annular shape when viewed in the layer-stacked direction. Therefore, the sealing layer may have one corner, or may not have the corner. 
     EXAMPLES 
     The present invention will be described in more detail by Examples hereinafter, but the present invention is not limited to the examples. 
     (Example 1) (a) of  FIG. 8  is a schematic plan view illustrating a light-emitting element for a test, and (b) of  FIG. 8  is a schematic sectional view taken along F-F line in (a) of  FIG. 8 . As illustrated in (a) and (b) of  FIG. 8 , a first substrate  102  in which a counter boring portion  102   b  was disposed on a main surface  102   a,  and a second substrate  103  in which an organic EL element part  104  was disposed were stuck by a frame-shaped sealing layer  106 , thereby, a light-emitting element  101  for the test was prepared. In a sealed space S of the light-emitting element  101  for the test, an area which was filled with a filler  107 , and an area (void V) which was not filled with the filler  107  were disposed. In the void V on the first substrate  102 , a drying agent  121  (manufactured by Futaba Corporation, product name: OleDry P 2 ) was disposed. The counter boring portion  102   b  is equivalent to the groove  2   b  in the embodiment described above. Hereinafter, a preparing method of the light-emitting element  101  for the test will be described. 
     First, the first substrate  102  that was a glass substrate of which the thickness was 0.5 mm was prepared. Next, on the main surface  102   a  of the first substrate  102 , the counter boring portions  102   b  was formed in a portion not overlapping all of the sealing layer  106  and the organic EL element part  104 . Therefore, the drying agent  121  was disposed on counter boring portion  102   b.    
     Separately from the first substrate  102 , the second substrate  103  that was a glass substrate was prepared. Next, the organic EL element part  104  was disposed on a main surface  103   a  of the second substrate  103 . 
     Hereinafter, a forming method of the organic EL light-emitting element in the organic EL element part  104  will be described. First, an ITO film of which the thickness was 135 nm was formed on the main surface  103   a.  Next, the ITO film was patterned, thereby, an anode was formed. Next, a silicon oxide film of which the thickness was 0.1 μm was formed by a chemical vapor deposition method (CVD method). Next, the silicon oxide film was patterned, thereby, an interlayer insulating film that exposed the anode was formed. Next, the second substrate  103  was cleaned. Next, the dried second substrate  103  was accommodated in a vacuum evaporation device, and an organic light-emitting layer was formed on the anode. Specifically, a hole injection layer of which the thickness was 40 nm, a hole transport layer of which the thickness was 40 nm, a light-emitting layer of which the thickness was 10 nm, an electron transport layer of which the thickness was 65 nm, and an electron injection layer of which the thickness was 2.5 nm were formed in sequence on the anode, thereby, the organic light-emitting layer was formed. Therefore, a cathode was formed on the organic light-emitting layer, thereby, the organic EL element part  104  was formed. Specifically, aluminum of which the thickness was 1 nm, and an IZO film of which the thickness was 100 nm were formed in sequence on the organic light-emitting layer, thereby, the cathode was formed. The IZO film was formed by a sputtering method. 
     Next, onto an area which was surrounded by the counter boring portion  102   b  in the main surface  102   a  of the first substrate  102 , the filler  107  was applied using a dispenser. Onto an edge area  102   d  which surrounded the counter boring portion  102   b  in the main surface  102   a  of the first substrate  102 , a sealing material of which the thickness was 20 μm was applied using the dispenser. The filler  107  includes a transparent liquid drying agent (manufactured by Futaba Corporation, product name: OleDry F). The sealing material is an ultraviolet ray curable resin (manufactured by ThreeBond Group) into which the spacers are dispersed. 
     Next, under the reduced pressure, the main surface  102   a  of the first substrate  102  and the main surface  103   a  of the second substrate  103  faced each other, and the first substrate  102  and the second substrate  103  were bonded to each other through the sealing material. Next, under the atmospheric pressure, after the sealing material was irradiated with the ultraviolet ray, the first substrate  102  and the second substrate  103  which were bonded to each other were heated under the conditions of 85° C. and 180 minutes. Thereby, the sealing material was cured with the ultraviolet ray, and the sealing layer  106  was formed. At the time of irradiating the sealing material with the ultraviolet ray, the organic EL element part  104  was set to be not irradiated with the ultraviolet ray. Through the processes described above, the light-emitting element  101  for the test in Example 1 was formed. 
     (Example 2) A light-emitting element for the test was prepared, by a method which was the same as that in Example 1 except that a silicone-based transparent heat-curing type resin (manufactured by Shin-Etsu Chemical Co., Ltd.) was used as a filler  107 . 
     (Comparative Example) A light-emitting element for the test was prepared, by a method which was the same as that in Example 1 except that the counter boring portion  102   b  was not disposed in the first substrate  102 , the drying agent  121  was not disposed on the main surface  102   a,  and the sealed space S was filled with the filler  107  without the void. 
     (High Temperature and High Humidity Accelerated Life Test) 
     A high temperature and high humidity accelerated life test was performed with respect to each of the light-emitting element  101  for the test in Example 1, the light-emitting element for the test in Example 2, and the light-emitting element for the test in Comparative Example, and a change of a light-emitting area of the organic EL element part in each light-emitting element for the test was measured. More specifically, the change of a predetermined organic EL elements (pixel) in each organic EL element part was measured. In the high temperature and high humidity accelerated life test, each light-emitting element for the test was left to stand for approximately 1500 hours under the conditions that the temperature was set to be 60° C., and the humidity was set to be 95%. 
       FIG. 9  is a graph illustrating the light-emitting area changes of Examples 1 and 2, and Comparative Example. In  FIG. 9 , a vertical axis indicates a proportion of an area which emits the light in the organic EL element part, and a horizontal axis indicates test time. A graph  41  illustrates a measurement result of Example 1, and a graph  42  illustrates a measurement result of Comparative Example. 
     As illustrated in  FIG. 9 , at the time of a test start, a whole of the organic EL element part in Comparative Example emitted the light. That is, the proportion of the light-emitting area in Comparative Example at the time of the test start was 100%. However, from around the test time exceeding 500 hours, the proportion of the light-emitting area in Comparative Example was lowered. When the test time elapsed approximately 1000 hours, the proportion of the light-emitting area in Comparative Example was approximately 50%. In addition, when the test time exceeded approximately 1500 hours, the proportion of the light-emitting area in Comparative Example was substantially 0. 
     On the contrary, in Example 1, even in a case where the test time exceeded approximately 1500 hours, the proportion of the light-emitting area was substantially equal to an initial value. In  FIG. 9 , the change of the light-emitting area in Example 2 was not illustrated, but in Example 2, a result which was substantially equal to that in Example 1 was obtained. That is, in all of Examples 1 and 2, even if the test time exceeded approximately 1500 hours, the proportion of the light-emitting area was substantially equal to the initial value. 
     From the results, it is found out that durability against the moisture of the light-emitting element for the test is particularly improved, by disposing the void V in at least the sealed space S, and disposing the drying agent  121  in the void V. 
     Reference Signs List 
       1 ,  1 A,  1 B: organic EL display device 
       2 ,  2 A,  2 B,  2 C: first substrate 
       2   a:  main surface (first main surface) 
       2   b:  groove 
       2   c:  edge 
       2   d:  edge area 
       3 : second substrate 
       3   a:  main surface (second main surface) 
       4 ,  4 A: organic EL element part 
       6 : sealing layer 
       6   a  to  6   d:  corner part 
       6   e:  inner side wall 
       7 : filler 
       11 ,  11 A: organic EL element 
       21 : drying agent 
       31   a:  groove (first groove) 
       31   b:  groove (second groove) 
     S: sealed space 
     V: void 
     W 1  to W 4 : width