Abstract:
Provided is a narrow-frame organic EL panel for suppressing unevenness in the brightness of light emission. The present invention involves positioning the following on a translucent support substrate: a translucent first electrode to which power is supplied from an external power source via common wiring, a second electrode for forming a pair with the first electrode, and an organic EL element in which an organic layer having at least a light-emitting layer is sandwiched between the first electrode and the second electrode. In addition, a sealing member is positioned so as to cover the organic EL element in an airtight manner, an auxiliary electrode having a lower specific resistance than that of the first electrode is formed on the first electrode, a groove is provided in at least a section of the sealing member, and an auxiliary conductive part comprising a conductive material is positioned in the groove.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to an organic EL panel and a method for producing the same. 
       BACKGROUND ART 
       [0002]    It is necessary to suppress voltage drop in common wiring in order to cause an organic EL panel to uniformly emit light, and PTL 1 discloses an organic EL panel that places an auxiliary electrode having a lower electrical resistivity than that of a transparent electrode on common wiring of the transparent electrode to reduce an electrical resistivity of the transparent electrode and suppress voltage drop caused by the transparent electrode. 
       CITATION LIST 
     Patent Literature 
       [0003]    PTL 1: JP-A-2003-123990 
       SUMMARY OF INVENTION 
     Technical Problem(s) 
       [0004]    However, an organic EL panel serving as a light source is required to uniformly emit light at a high brightness, and therefore, in the case where the organic EL panel is formed to have a large area or a long length, an electric current flowing through common wiring is increased, and voltage drop in the common wiring is further increased. In order to suppress voltage drop in the common wiring, it is necessary to increase a wiring width of the common wiring, and therefore an area of the common wiring from an external power source placed in an outer region (frame) in a light-emitting unit of the organic EL panel is increased and the frame of the organic EL panel is increased. Thus, it is difficult to reduce a size of the organic EL panel. 
         [0005]    The invention has been made in view of the above problems, and an object thereof is to provide a narrow-frame organic EL panel for suppressing unevenness in light emission luminance and a method for producing the same. 
       Solution to Problem(s) 
       [0006]    In order to achieve the above object, an organic EL panel according to a first aspect of the invention includes: a translucent first electrode to which power is supplied from an external power source via common wiring; a second electrode paired with the first electrode; an organic layer sandwiched between the first electrode and the second electrode, the organic layer having at least a light-emitting layer; a support substrate supporting the first electrode, the second electrode, and the organic layer; and a sealing member covering the first electrode, the second electrode, and the organic layer between the sealing member and the support substrate, wherein: an auxiliary electrode having a lower resistivity than a resistivity of the first electrode is provided on the first electrode; and a groove is provided in at least a part of the sealing member and an auxiliary conductive part is provided in the groove, the auxiliary conductive part being in contact with the auxiliary electrode and being made of a conductive material. 
         [0007]    A method for producing an organic EL panel according to a second aspect is a method for producing an organic EL panel by dividing a common substrate into a plurality of organic EL panels, including: a step of forming a first electrode made of a translucent conductive material on a translucent support substrate and forming an auxiliary electrode having a lower resistivity than a resistivity of the conductive material on a part of the first electrode; a step of sequentially laminating an organic layer and a second electrode paired with the first electrode, the organic layer being a layer in which the auxiliary electrode is covered with an insulating material and having at least a light-emitting layer on the first electrode; a step of sealing the first electrode, the auxiliary electrode, the second electrode, and the organic layer with a sealing member on the support substrate; a division step of dividing the common substrate generated in the above step into a plurality of organic EL panels; and a step of forming an auxiliary conductive part made of a conductive material in a groove formed by the sealing member on an outer surface of the organic EL panel generated in the division step so that the auxiliary conductive part is brought into contact with the auxiliary electrode. 
       Advantageous Effects of Invention 
       [0008]    According to the invention, it is possible to provide a narrow-frame organic EL panel for suppressing unevenness in light emission luminance and a method for producing the same. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0009]      FIG. 1  is a planar view of a multi-organic EL substrate in an embodiment of the invention. 
           [0010]      FIG. 2  is a cross-sectional view of the multi-organic EL substrate in the above embodiment, which is across-sectional view taken along A-A in  FIG. 1 . 
           [0011]      FIG. 3  is cross-sectional views of the multi-organic EL substrate in the above embodiment, which is cross-sectional views taken along B-B in  FIG. 1 . 
           [0012]      FIG. 4  is a cross-sectional view of the organic EL panel in the above embodiment, which is a cross-sectional view that does not cross an auxiliary electrode. 
           [0013]      FIG. 5  is (a) a cross-sectional view and (b) a planar view of an organic EL panel in a modification example. 
           [0014]      FIG. 6  is cross-sectional views of an organic EL panel in a modification example. 
       
    
    
     DESCRIPTION OF EMBODIMENTS 
       [0015]    Hereinafter, an embodiment of the invention will be described with reference to the attached drawings. 
         [0016]    An organic EL panel  100  mainly includes a support substrate  10 , a first electrode  20  formed on the support substrate  10 , an auxiliary electrode  30  formed on a part of the first electrode  20 , an insulating layer  40 , an organic layer  50 , a second electrode  60 , a sealing member  70 , an adhesive agent  80 , and an auxiliary conductive part  90 . The organic EL panel  100  includes first terminal parts  101  and second terminal parts  102 , connects the first terminal parts  101  to an anode of an external power source (not shown) and connects the second terminal parts  102  to a cathode of the external power source, and causes a light-emitting unit E to emit light by supplying power to the first terminal parts  101  (second terminal parts  102 ). The organic EL panel  100  in this embodiment is formed by generating a plurality of organic EL panels  100  with the use of a common substrate (multi-organic EL substrate  100   a ) and then dividing the common substrate. In this way, the individual organic EL panels  100  are formed. 
         [0017]    The support substrate  10  is made of a rectangular transparent glass material and is an electrically insulating substrate. Although a glass material is used for the support substrate  10  in this example, not only the glass material but also transparent materials such as plastics and ceramics can be used for the substrate. 
         [0018]    The first electrode  20  is made of a translucent conductive material such as ITO and is translucent wiring obtained by forming an electrode film on the support substrate  10  by means such as a vapor deposition method or a sputtering method and then patterning the electrode film to a predetermined shape by a photolithography method or the like. Although the first electrode  20  is formed on the whole light-emitting unit E in this embodiment, the first electrode  20  may be formed as a plurality of stripes vertical to left and right sides of the organic EL panel  100  in  FIG. 1 . The first electrode  20  has a common wiring structure in which the first electrode  20  is electrically connected to the external power source via the first terminal parts  101  described below and power is supplied to the whole first electrode  20  on the basis of supply of power from the external power source via the first terminal parts  101 . 
         [0019]    The auxiliary electrode  30  is non-translucent wiring obtained by forming a metal such as aluminum having a lower resistivity than that of the translucent conductive material of the first electrode  20  on the first electrode  20  by means such as the sputtering method so that the metal has a film of a single layer or laminated layers having a film thickness of 50 to 1500 nm and patterning the metal to a predetermined shape by means such as the photolithography method. In this embodiment, the auxiliary electrode  30  is formed on the first electrode  20  as a plurality of stripes vertical to the left and right sides of the organic EL panel  100  in  FIG. 1 . 
         [0020]    The insulating layer  40  is made of, for example, a polymide-based transparent insulating material and is formed as layered thin films of about 1.0 μm by a spin coating method or the like and is then patterned to a desired shape by the photolithography method. The insulating layer  40  is formed between the auxiliary electrode  30  and the organic layer  50  described below so as to cover the auxiliary electrode  30  formed as a stripe on the first electrode  20 , thereby preventing short circuit between the first electrode  20  and the second electrode  60  described below. 
         [0021]    The organic layer  50  is formed on the first electrode  20 , is formed by sequentially laminating a hole injection transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer by means such as the vapor deposition method, and emits, for example, white light. Note that, in the organic layer  50 , the light-emitting layer may be formed by a single layer or may be formed by adding another layer. 
         [0022]    The second electrode  60  is formed as a layer by providing a metallic conductive material having a higher conductivity than that of the first electrode  20  such as aluminum or magnesium silver on a back surface side of the organic layer  50  by means such as the vapor deposition method. The second electrode  60  has a common wiring structure in which the second electrode  60  is electrically connected to the external power source via the second terminal parts  102  described below and power is supplied to the whole second electrode  60  on the basis of supply of power from the external power source via the second terminal parts  102 . 
         [0023]    The sealing member  70  is obtained by forming a plate member made of, for example, a glass material so that the plate member has a recessed shape by an appropriate method such as sandblasting, cutting, or etching and includes a plate part  71  facing to the organic layer  50 , a support part  72  extending toward the support substrate  10  so as to surround the plate part  71 , a division part  73  to be divided when the multi-organic EL substrate  100   a  is divided into the plurality of organic EL panels  100 , and a groove  74  formed on the outside of the support part  72 , the groove being formed by the plate part  71  and the support part  72 . In this embodiment, the groove  74  is formed by any one of a thermal press molding method, an etching method, a sandblasting method, and a cutting method. 
         [0024]    The adhesive agent  80  is made of, for example, ultraviolet-curable epoxy resin and is used to cause the support part  72  to adhere to the support substrate  10  (auxiliary electrodes  30 ), and therefore the organic layer  50  is provided on the support substrate  10  in an airtight manner, and the organic layer  50  is sealed by the sealing member  70  and the support substrate  10  (auxiliary electrodes  30 ). Further, the sealing member  70  is formed to be slightly smaller than the support substrate  10  so that end parts of the first electrode  20  and the second electrode  60  are exposed to the outside, and a part of the support part  72  is provided to be overlaid with the first electrode  20  and the second electrode  60 . 
         [0025]    The auxiliary conductive part  90  is made of, for example, a conductive paste having a volume resistivity of 1.5×10 −4  Ω/cm and a viscosity of 10 Pa·s. After the multi-organic EL substrate  100   a  is divided, the auxiliary conductive part  90  is applied to the groove  74  formed by the plate part  71 , the support part  72 , and the auxiliary electrode  30  on side surfaces of each organic EL panel  100  so that the auxiliary conductive part  90  is electrically connected to the auxiliary electrode  30  and is then cured by heat. 
         [0026]    The first terminal part  101  is a part of the first electrode  20  and the auxiliary electrode  30  formed on the support substrate  10 , the part being extracted from the inside of the sealing member  70  to the outside thereof, and electrically connects the first electrode  20  and the auxiliary electrode  30  to the external power source. 
         [0027]    The second terminal part  102  is formed by laminating a metal layer (not shown) made of a metal material having a low resistivity, such as chromium, on a base part (not shown) which is made of the same material as that of the first electrode  20  at the same time and electrically connects the second electrode  60  to the external power source. 
         [0028]    The organic EL panel  100  is made up of the above parts. The organic EL panel  100  is a so-called bottom-emission type organic EL panel that emits light from the support-substrate- 10  side. 
         [0029]    A method for producing the organic EL panel  100  will be described with reference to  FIG. 3 .  FIG. 3  is cross-sectional views of the multi-organic EL substrate  100   a , which is cross-sectional views taken along B-B in  FIG. 1 . Note that, although  FIG. 3  is cross-sectional views passing through the auxiliary electrode  30 ,  FIG. 4  is a cross-sectional view that does not pass through the auxiliary electrode  30 , which is seen from the same direction. 
         [0030]    First, in a “first electrode forming step,  FIG. 3( a ) ”, the first electrode  20  and the auxiliary electrode  30  are formed on the support substrate  10  by means such as the vapor deposition method or the sputtering method, and then the slit-like first electrode  20  and auxiliary electrode  30  are formed on the support substrate  10  by the photolithography method or the like. 
         [0031]    Next, the insulating layer  40  is formed to have a thin film shape on a back surface side of the auxiliary electrode  30  by the spin coating method or the like and is then patterned to a desired shape by the photolithography method. Then, in an “organic layer forming step and second electrode forming step,  FIG. 3( b ) ”, the organic layer  50  is laminated to correspond to the first electrode  20 , and the second electrode  60  is further laminated on the organic layer  50 . 
         [0032]    Next, in a “bonding step,  FIG. 3( c ) ”, the sealing member  70  to which the adhesive agent  80  is applied and the support substrate  10  are overlaid in a nitrogen atmosphere while being kept in parallel by an overlaying device (not shown) so that each plate part  71  corresponds to the light-emitting unit E, and the support part  72  of the sealing member  70  and the support substrate  10  (auxiliary electrodes  30 ) are bonded and fixed by irradiation with ultraviolet rays, and thus the multi-organic EL substrate  100   a  including the plurality of organic EL panels  100  is obtained. 
         [0033]    Next, in a “cutting step,  FIG. 3( d ) ”, the division part  73 , which is a boundary between the plurality of organic EL panels  100  in the multi-organic EL substrate  100   a  obtained in the bonding step, is cut by means such as a scribing method, and an excess part  74   a , which is an excess portion of the groove  74 , is cut by means such as the scribing method, and thus the individual organic EL panels  100  are obtained. 
         [0034]    Then, in an “applying step,  FIG. 3( e ) ”, the auxiliary conductive part  90  is applied to the groove  74  of the organic EL panel  100  with the use of a needle or the like, and after application, the auxiliary conductive part  90  is cured. 
         [0035]    The organic EL panel  100  in this embodiment described above is obtained by providing, on the translucent support substrate  10 , the translucent first electrode  20  to which power is supplied from an external power source via common wiring, the second electrode  60  paired with the first electrode  20 , and an organic EL element in which the organic layer  50  having at least a light-emitting layer is sandwiched between the first electrode  20  and the second electrode  60  and providing the sealing member  70  covering the organic EL element in an airtight manner, and the auxiliary electrode  30  having a lower resistivity than that of the first electrode  20  is formed on the first electrode  20 , the groove  74  is provided on at least a part of the sealing member  70 , and the auxiliary conductive part  90  made of a conductive material is placed in the groove  74 . 
         [0036]    With this, an electrical resistivity against the first electrode  20  over the whole light-emitting unit E can be kept low even in the case where the width of the first terminal part  101  of the common wiring is not increased. That is, it is possible to cause the light-emitting unit E to uniformly emit light while keeping the electrical resistivity of the common wiring low, and therefore it is possible to provide the narrow-frame organic EL panel  100  having a narrow frame. 
         [0037]    Note that the invention is not limited by the embodiment described above and the drawings. It is possible to make modifications (including elimination of constituent elements) as appropriate without changing the scope of the invention. 
         [0038]    In the above embodiment, the organic EL element (organic layer  50 ), the support part  72  of the sealing member  70 , the auxiliary conductive part  90 , and the first terminal part  101  are placed in order from the center of the organic EL panel  100  to the outside thereof, and the first terminal part  101  is placed at an edge of the organic EL panel  100 . However, as shown in  FIG. 5( a ) , the auxiliary conductive parts  90  may be placed on the outside of the organic EL panel  100 , and the first terminal parts  101  may be placed at both ends of the second terminal part  102  (vertical parts of the second terminal part  102  in  FIG. 5( b ) ) so that electricity can be conducted to the auxiliary conductive parts  90 . With this, it is unnecessary to provide a space for providing the first terminal part  101  on one opposite side of the organic EL panel  100 , and therefore it is possible to provide the narrow-frame organic EL panel  100  having a narrow frame. 
         [0039]    As shown in  FIGS. 6( a ) and 6( b ) , a conducting wire  91 , which has a volume resistivity of 1.5×10 −7  Ω/cm and is made of, for example, a tin coating copper wire having a diameter of 0.2 mm, may be provided in the auxiliary conductive part  90 . With this structure, it is possible to keep the electrical resistivity of the common wiring (first electrode  20 ) lower and cause the light-emitting unit E to uniformly emit light, and therefore it is possible to provide the narrow-frame organic EL panel  100  having a narrow frame. 
       INDUSTRIAL APPLICABILITY 
       [0040]    The invention is suitable for an organic EL panel serving as a light source. 
       REFERENCE SIGNS LIST 
       [0000]    
       
           100  organic EL panel 
           100   a  multi-organic EL substrate 
           101  first terminal part 
           102  second terminal part 
           10  support substrate 
           20  first electrode 
           30  auxiliary electrode 
           40  insulating layer 
           50  organic layer 
           60  second electrode 
           70  sealing member 
           71  plate part 
           72  support part 
           73  division part 
           74  groove 
           80  adhesive agent 
           90  auxiliary conductive part 
           91  conducting wire 
         E light-emitting unit