Abstract:
A method of manufacturing an organic-light-emitting-diode (OLED) flat-panel light-source apparatus. The method includes depositing a metal layer on a substrate and patterning the metal layer to form a plurality of subsidiary electrodes, forming an insulating layer on the substrate including the plurality of subsidiary electrodes and forming a first subsidiary electrode layer by etching the insulating layer until some of the plurality of subsidiary electrodes are exposed, and sequentially forming an anode, an organic emission layer (EML), and a cathode on the substrate on which the first subsidiary electrode layer is formed.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application is a divisional of co-pending application Ser. No. 13/078,095 filed on Apr. 1, 2011, and claims priority to and the benefit of Korean Patent Application Nos. 10-2010-0032773 filed Apr. 9, 2010, and 10-2010-0107660 filed Nov. 1, 2010, the disclosure of which is incorporated herein by reference in its entirety. 
     
    
     BACKGROUND 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to an organic-light-emitting-diode (OLED) flat-panel light-source apparatus and, more particularly, to an OLED flat-panel light-source apparatus and a method of manufacturing the same, which may improve the uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus required for an illumination system and a display device. 
         [0004]    2. Discussion of Related Art 
         [0005]    An organic light emitting diode (OLED) flat-panel light-source technique may be applied in various fields including an energy-saving eco-friendly illumination system, a flexible display device, a medical illumination system, and a backlight unit (BLU) of an LCD display device. 
         [0006]      FIGS. 1 and 2  are a cross-sectional view and plan view, respectively, of a conventional OLED flat-panel light-source apparatus. 
         [0007]    Referring to  FIGS. 1 and 2 , the conventional OLED flat-panel light-source apparatus may include a substrate  110 , an anode  120 , an organic emission layer (EML)  130 , and a cathode  140 . 
         [0008]    The organic EML  130  may be interposed between the anode  120  and the cathode  140 , each of which may be formed of a transparent metal layer or a reflective metal layer. When power is applied between the anode  120  and the cathode  140 , the organic EML  130  may emit light. 
         [0009]    However, the conventional OLED flat-panel light-source apparatus should supply current to the organic EML  130  through the anode  120  and the cathode  140  so that the organic EML  130  can emit light. In this case, IR-drop may occur due to resistance components of the anode  120  and the cathode  140 . Thus, the conventional OLED flat-panel light-source apparatus may have non-uniform electrical and optical properties according to a position of an emission region due to the IR-drop. Also, in the conventional OLED flat-panel light-source apparatus, the emission region may be increased due to the scaling-up of OLED flat-panel light-surface apparatuses, thus increasing the non-uniformity of the electrical and optical properties. 
         [0010]    In order to overcome the above-described drawbacks, an OLED flat-panel light-source apparatus using a subsidiary electrode layer has lately been proposed to reduce a sheet resistance component of an electrode and the non-uniformity of the electrical and optical properties due to the IR-drop. 
         [0011]      FIGS. 3 through 6  are diagrams of an OLED flat-panel light-source apparatus including a subsidiary electrode layer. Specifically,  FIGS. 3 and 4  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and an organic material, and  FIGS. 5 and 6  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and a substrate. 
         [0012]    Referring to  FIGS. 3 through 6 , the OLED flat-panel light-source apparatus may include a substrate  310 , an anode  320 , an organic EML  330 , a cathode  340 , and a subsidiary electrode layer. Here, the subsidiary electrode layer may include a plurality of subsidiary electrodes  350  and an insulating layer  354  configured to compensate the coverage of the plurality of subsidiary electrodes  350 . 
         [0013]    Each of the subsidiary electrodes  350  may include a metal layer  352  having a low sheet resistance. Thus, the plurality of subsidiary electrodes  350  may reduce a sheet-resistance component of the anode  320  or the cathode  340 , thereby reducing non-uniformity due to IR-drop. 
         [0014]    However, it is difficult to embody a large-area OLED flat-panel light-source apparatus having uniform electrical and optical properties using a conventional method of manufacturing a large-area OLED flat-panel light-source apparatus. 
       SUMMARY OF THE INVENTION 
       [0015]    The present invention is directed to an organic-light-emitting-diode (OLED) flat-panel light-source apparatus and a method of manufacturing the same, which may improve the electrical and optical properties of a large-area OLED flat-panel light-source apparatus. 
         [0016]    One aspect of the present invention provides an OLED flat-panel light-source apparatus including: an anode and a cathode, to which externally applied power is applied, disposed on a substrate; an organic emission layer (EML) interposed between the anode and the cathode and configured to emit light due to power supplied through the anode and the cathode; and a subsidiary electrode layer including a plurality of subsidiary electrodes bonded to the anode or the cathode and configured to supply power to the anode or the cathode or electrically insulated from the anode or the cathode and configured to supply power to other emission regions. 
         [0017]    Another aspect of the present invention provides a method of manufacturing an OLED flat-panel light-source apparatus. The method includes: depositing a metal layer on a substrate and patterning the metal layer to form a plurality of subsidiary electrodes; forming an insulating layer on the substrate including the plurality of subsidiary electrodes and forming a first subsidiary electrode layer by etching the insulating layer until some of the plurality of subsidiary electrodes are exposed; and sequentially forming an anode, an organic EML, and a cathode on the substrate on which the first subsidiary electrode layer is formed. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0018]    The above and other features and advantages of the present invention will become more apparent to those of ordinary skill in the art by describing in detail exemplary embodiments thereof with reference to the attached drawings in which: 
           [0019]      FIGS. 1 and 2  are a cross-sectional view and plan view, respectively, of a conventional organic-light-emitting-diode (OLED) flat-panel light-source apparatus; 
           [0020]      FIGS. 3 and 4  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and an organic material; 
           [0021]      FIGS. 5 and 6  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus in which a subsidiary electrode is formed between an anode and a substrate; 
           [0022]      FIGS. 7A ,  7 B, and  8  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a first exemplary embodiment of the present invention; 
           [0023]      FIGS. 9 and 10  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a second exemplary embodiment of the present invention; 
           [0024]      FIGS. 11 and 12  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a third exemplary embodiment of the present invention; 
           [0025]      FIGS. 13A ,  13 B and  14  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a fourth exemplary embodiment of the present invention; and 
           [0026]      FIGS. 15 through 19  are process flowcharts illustrating a method of manufacturing the OLED flat-panel light-source apparatus shown in  FIGS. 11 and 12 . 
       
    
    
     DETAILED DESCRIPTION OF EMBODIMENTS 
       [0027]    The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. Descriptions of well-known components and processing techniques are omitted so as not to unnecessarily obscure the embodiments of the present invention. 
         [0028]      FIGS. 7A ,  7 B, and  8  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a first exemplary embodiment of the present invention. Specifically,  FIG. 7A  is a cross-sectional view taken along line m-m′ of the OLED flat-panel light-source apparatus of  FIG. 8 , and  FIG. 7B  is a cross-sectional view taken along line n-n′ of the OLED flat-panel light-source apparatus of  FIG. 8 . 
         [0029]    Referring to  FIGS. 7A ,  7 B, and  8 , the OLED flat-panel light-source apparatus according to the present invention may include a substrate  710 , an anode  720 , an organic EML  730 , a cathode  740 , and a subsidiary electrode layer. Here, the subsidiary electrode layer may include first through third subsidiary electrodes  750 ,  760 , and  770  and an insulating layer  754 . Here, the subsidiary electrode layer may include at least one subsidiary electrode. 
         [0030]    The anode  720  and the cathode  740  may be sequentially formed on the substrate  710 , and externally applied power may be supplied to the organic EML  730 . Here, each of the anode  720  and the cathode  740  may include a transparent metal layer or a reflective metal layer. 
         [0031]    The organic EML  730  may be interposed between the anode  720  and the cathode  740  and emit light due to power supplied through the anode  720  and the cathode  740 . Here, the organic EML  730  may be formed of an organic compound including an electron transport layer (ETL), an EML, and a hole transport layer (HTL). 
         [0032]    The subsidiary electrode layer may include first and third subsidiary electrodes  750  and  770 , which may be bonded to the anode  720  and function to reduce a resistance component of the anode  720 , and a second subsidiary electrode  760 , which may supply power to other emission regions of the OLED flat-panel light-source apparatus. Here, each of the first through third subsidiary electrodes  750 ,  760 , and  770  may include a metal layer  752  having a low sheet resistance, and the second subsidiary electrode  760  may be electrically insulated from the anode  720  by an insulating layer  754 . Hereinafter, construction and operation of each of the subsidiary electrodes  750 ,  760 , and  770  will be described in detail. 
         [0033]    Each of the first and third subsidiary electrodes  750  and  770  may be electrically connected in parallel to the anode  720  in the emission region and function to reduce the influence of IR-drop due to a driving current. That is, the first and third subsidiary electrodes  750  and  770  may supply additional power to the anode  720  and reduce the influence of IR-drop. 
         [0034]    The second subsidiary electrode  760  may supply power to the other emission regions of the OLED flat-panel light-source apparatus. Specifically, as shown in  FIG. 7A , the second subsidiary electrode  760  may be electrically insulated from the anode  720  by the insulating layer  754  and serve as a coated electric wire for transmitting current in the emission region that may be less affected by the IR-drop. In contrast, as shown in  FIG. 7B , the second subsidiary electrode  760  may be bonded to the anode  720  and serve to supply power in the emission region that may be more affected by the IR-drop. 
         [0035]    Accordingly, the OLED flat-panel light-source apparatus according to the present invention may not be affected by IR-drop but receive power using the second subsidiary electrode  760  even in the emission region disposed a far distance from a driver unit (not shown). Thus, the non-uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus due to the IR-drop of the anode  720  may be overcome without additional thin layers and manufacturing processes. 
         [0036]      FIGS. 9 and 10  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a second exemplary embodiment of the present invention. Specifically,  FIG. 9  is a cross-sectional view taken along line m-m′ of the OLED flat-panel light-source apparatus of  FIG. 10 . 
         [0037]    Referring to  FIGS. 9 and 10 , the OLED flat-panel light-source apparatus according to the second embodiment may include a subsidiary electrode layer disposed on a cathode  940  unlike the OLED flat-panel light-source apparatus according to the first embodiment. 
         [0038]    The subsidiary electrode layer may include first and third subsidiary electrodes  950  and  970 , which may be bonded to the cathode  940 , and function to reduce a resistance component of the cathode  940 , and a second subsidiary electrode  960 , which may be separated from the cathode  940  and function to supply power to other emission regions of the flat-panel light-source apparatus. Here, each of the first through third subsidiary electrodes  950 ,  960 , and  970  may include a metal layer  952  having a low sheet resistance, and the second subsidiary electrode  960  may be electrically insulated from the cathode  940  by an insulating layer  954 . 
         [0039]    Each of the first and third subsidiary electrodes  950  and  970  may be electrically connected in parallel to the cathode  940  in an emission region and reduce the influence of IR-drop due to a driving current. 
         [0040]    The second subsidiary electrode  960  may supply power to the other emission regions of the OLED flat-panel light-source apparatus. Specifically, the second subsidiary electrode  960  may be electrically insulated from the cathode  940  by the insulating layer  954  and serve as a coated electric wire for transmitting current in the emission region that may be less affected by the IR-drop. In contrast, the second subsidiary electrode  960  may be bonded to the cathode  940  and serve to supply power in the emission region that may be more affected by the IR-drop. 
         [0041]    Accordingly, the non-uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus due to the IR-drop of the cathode  940  may be overcome. 
         [0042]      FIGS. 11 and 12  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a third exemplary embodiment of the present invention. Specifically,  FIG. 11  is a cross-sectional view taken along line m-m′ of the OLED flat-panel light-source apparatus of  FIG. 12 . 
         [0043]    Referring to  FIGS. 11 and 12 , the OLED flat-panel light-source apparatus according to the third embodiment may include a first subsidiary electrode layer interposed between a substrate  1110  and an anode  1120  and a second subsidiary electrode layer disposed on a cathode  1140 . 
         [0044]    The first subsidiary electrode layer may include first and third subsidiary electrodes  1152  and  1172 , which may be bonded to the anode  1120  and reduce a resistance component of the anode  1120 , and a second subsidiary electrode  1162 , which may be separated from the anode  1120  and supply power to other emission regions of the OLED flat-panel light-source apparatus. Here, each of the subsidiary electrodes  1152 ,  1162 , and  1172  may include a metal layer  1153  having a low sheet resistance, and the second subsidiary electrode  1162  may be electrically insulated from the anode  1120  by an insulating layer  1155 . 
         [0045]    Each of the first and third subsidiary electrodes  1152  and  1172  may be electrically connected in parallel to the anode  1120  in an emission region and reduce the influence of IR-drop due to a driving current. 
         [0046]    The second subsidiary electrode  1162  may supply power to the other emission regions of the OLED flat-panel light-source apparatus. The second subsidiary electrode  1162  may be electrically insulated from the anode  1120  and serve as a coated electric wire for transmitting current in an emission region that may be less affected by the IR-drop. In contrast, the second subsidiary electrode  1162  may be bonded to the anode  1120  and supply power in an emission region that may be more affected by the IR-drop. 
         [0047]    The second subsidiary electrode layer may include fourth and sixth subsidiary electrodes  1150  and  1170 , which may be bonded to the cathode  1140  and reduce a resistance component of the cathode  1140 , and a fifth subsidiary electrode  1160 , which may be separated from the cathode  1140  and supply power to the other emission regions of the OLED flat-panel light-source apparatus. Here, each of the subsidiary electrodes  1150 ,  1160 , and  1170  may include a metal layer  1151  having a low sheet resistance, and the fifth subsidiary electrode  1160  may be electrically insulated from the cathode  1140  by an insulating layer  1155 . 
         [0048]    Each of the fourth and sixth subsidiary electrodes  1150  and  1170  may be electrically connected in parallel to the cathode  1140  in an emission region and reduce the influence of IR-drop due to a driving current. 
         [0049]    The fifth subsidiary electrode  1160  may supply power to the other emission regions of the OLED flat-panel light-source apparatus. Specifically, the fifth subsidiary electrode  1160  may be electrically insulated from the cathode  1140  and serve as a coated electric wire for transmitting current in an emission region that may be less affected by the IR-drop. In contrast, the fifth subsidiary electrode  1160  may be bonded to the cathode  1140  and serve to supply power in an emission region that may be more affected by the IR-drop. 
         [0050]    Accordingly, the non-uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus due to the IR-drop of an anode and a cathode may be overcome. 
         [0051]      FIGS. 13A ,  13 B and  14  are a cross-sectional view and plan view, respectively, of an OLED flat-panel light-source apparatus according to a fourth exemplary embodiment of the present invention. Specifically,  FIG. 13A  is a cross-sectional view taken along line m-m′ of the OLED flat-panel light-source apparatus of  FIG. 14 , and  FIG. 13B  is a cross-sectional view taken along line n-n′ of the OLED flat-panel light-source apparatus of  FIG. 14 . 
         [0052]    In the fourth embodiment, the above-described OLED flat-panel light-source apparatus including the subsidiary electrode layer may be structurally improved so that the OLED flat-panel light-source apparatus can include a plurality of subsidiary electrode layers. Also, from the plan view, the OLED flat-panel light-source apparatus according to the fourth embodiment may be configured to have a lattice structure, thereby reducing the influence of IR-drop. For brevity, an OLED flat-panel light-source apparatus including two subsidiary electrode layers will be described as an example. 
         [0053]    Referring to  FIGS. 13A ,  13 B, and  14 , the OLED flat-panel light-source apparatus according to the fourth embodiment may include a first subsidiary electrode layer including first and third subsidiary electrodes  1350  and  1370  and a first insulating layer  1354  and a second subsidiary electrode layer including second and fourth subsidiary electrodes  1360  and  1380  and a second insulating layer  1364 . Here, each of the first and third subsidiary electrodes  1350  and  1370  may include a first metal layer  1352 , and each of the second and fourth subsidiary electrodes  1360  and  1380  may include a second metal layer  1362 . 
         [0054]    As shown in  FIG. 13A , the first and third subsidiary electrodes  1350  and  1370  of the first subsidiary electrode layer may be electrically insulated from the anode  1320  and serve as coated electric wires for supplying power to other emission regions of the flat-panel light-source apparatus in an emission region that may be less affected by the IR-drop. Also, as shown in  FIG. 13B , the third subsidiary electrode  1370  of the first subsidiary electrode layer may be bonded to the anode  1320  and serve to supply power to the anode  1320  in an emission region that may be more affected by the IR-drop. Furthermore, the second subsidiary electrode layer may be bonded to the anode  1320  and reduce a resistance component of the anode  1320 . 
         [0055]    Hereinafter, a method of manufacturing the OLED flat-panel light-source apparatus according to the third embodiment of the present invention will be described. Here, since the methods of manufacturing the OLED flat-panel light-source apparatuses according to the first and second embodiments of the present invention include about the same processes as the method of manufacturing the OLED flat-panel light-source apparatus according to the third embodiment of the present invention, a detailed description thereof will be omitted. 
         [0056]      FIGS. 15 through 19  are process flowcharts illustrating a method of manufacturing the OLED flat-panel light-source apparatus shown in  FIGS. 11 and 12 . 
         [0057]    Referring to  FIG. 15 , a metal layer  1153  may be deposited on a substrate  1110  and patterned, thereby forming first through third subsidiary electrodes  1152 ,  1162 , and  1172 . Here, the metal layer  1153  may be formed using a metal having a sheet resistance. 
         [0058]    Referring to  FIG. 16 , an insulating layer  1155  may be formed on the substrate  1110  including the first through third subsidiary electrodes  1152 ,  1162 , and  1172  and etched to expose the second subsidiary electrode  1162  out of the first through third subsidiary electrodes  1152 ,  1162 , and  1172 , thereby forming a first subsidiary electrode layer. The first subsidiary electrode layer may include a plurality of subsidiary electrode layers. Here, since a method of forming the plurality of subsidiary electrode layers is obvious to those skilled in the art, a description thereof will be omitted. 
         [0059]    Referring to  FIG. 17 , an anode  1120 , an organic EML  1130 , and a cathode  1140  may be sequentially formed on the substrate  1110  having the first subsidiary electrode layer. 
         [0060]    Referring to  FIG. 18 , an insulating layer  1155  may be formed on the cathode  1140  and etched. Here, the insulating layer  1155  may electrically insulate a subsequent sixth subsidiary electrode  1160  from the cathode  1140 . 
         [0061]    Referring to  FIG. 19 , a metal layer  1151  may be formed on the cathode  1140  on which the insulating layer  1155  is formed. The metal layer  1151  may be patterned, thereby forming a second subsidiary electrode layer including fifth through seventh subsidiary electrodes  1150 ,  1160 , and  1170  on the insulating layer  1155  or the cathode  1140 . 
         [0062]    According to the present invention as described above, an OLED flat-panel light-source apparatus and a method of manufacturing the same can improve the uniformity of electrical and optical properties of a large-area OLED flat-panel light-source apparatus. 
         [0063]    Furthermore, the influence of IR-drop of an anode and a cathode can be overcome without classifying an OLED flat-panel light-source apparatus into pixels or segments so that a large-area OLED flat-panel light-source apparatus can be manufactured at low cost. 
         [0064]    In the drawings and specification, there have been disclosed typical exemplary embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation. As for the scope of the invention, it is to be set forth in the following claims. Therefore, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the present invention as defined by the following claims.