Patent Publication Number: US-2023155080-A1

Title: Display device, light-emitting device and electronic apparatus

Description:
TECHNICAL FIELD 
     The present disclosure relates to display devices, light-emitting devices, and electronic apparatuses. 
     BACKGROUND ART 
     As a light-emitting device such as a display device or a lighting device, there is known a light-emitting device including a light-emitting element having a light-emitting layer provided between a pair of electrodes and a protective layer covering the light-emitting element. The light-emitting device having the above-mentioned configuration has a step in a peripheral region that rises in a direction from the inner side of the light-emitting device toward the outer circumference side, and one electrode that constitutes the light-emitting element extends beyond the step to the outer circumference side of the light-emitting device. For example, PTL 1 discloses an organic light-emitting device  1  in which a pixel separation film  12  has a step on a wiring connection portion (contact portion)  24  that rises in the direction from the inner side of the organic light-emitting device  1  toward the outer circumference, and an upper electrode  23  extends beyond the step to the outer circumference of the organic light-emitting device  1 . 
     CITATION LIST 
     Patent Literature 
     [PTL 1]
     JP 2016-21380 A   

     SUMMARY 
     Technical Problem 
     However, as described above, in the light-emitting device in which one of the electrodes constituting the light-emitting element extends beyond the step to the outer circumference side, cracks may occur on the side surface (end surface) of a protective layer covering the contact portion. When such cracks occur, moisture or the like enters the display device from the side surfaces of the protective layer through the cracks, which lowers the reliability of the light-emitting device. 
     An object of the present disclosure is to provide a display device, a light-emitting device, and an electronic apparatus capable of suppressing deterioration in reliability. 
     Solution to Problem 
     In order to solve the above-mentioned problems, a first disclosure provides: 
     a display device including: a plurality of light-emitting elements;
 
a contact portion provided around a region in which the plurality of light-emitting elements are formed;
 
an insulating layer having a step on the contact portion; and
 
a protective layer covering the light-emitting elements, the contact portion, and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral portion connected to the contact portion; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the display device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
     A second disclosure provides: 
     a light-emitting device including: a plurality of light-emitting elements;
 
a contact portion provided around a region in which the plurality of light-emitting elements are formed;
 
an insulating layer having a step on the contact portion; and
 
a protective layer covering the light-emitting elements, the contact portion, and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral portion connected to the contact portion; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the light-emitting device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
     A third disclosure provides: 
     a display device including: a plurality of light-emitting elements;
 
an insulating layer having a step around a region in which the plurality of light-emitting elements are formed; and
 
a protective layer covering the light-emitting elements and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral edge extending to a periphery of the region; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the display device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
     A fourth disclosure provides: 
     a light-emitting device including: a plurality of light-emitting elements;
 
an insulating layer having a step around a region in which the plurality of light-emitting elements are formed; and
 
a protective layer covering the light-emitting elements and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral edge extending to a periphery of the region; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the light-emitting device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
     A fifth disclosure provides an electronic apparatus including the display device according to any one of the first disclosure and second disclosure, or the light-emitting device according to any one of third disclosure and fourth disclosure. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a plan view showing a configuration example of a display device according to an embodiment of the present disclosure. 
         FIG.  2    is a cross-sectional view taken along line II-II of  FIG.  1   . 
         FIG.  3    is an enlarged plan view showing a portion of the display device. 
         FIG.  4    is a cross-sectional view showing the configuration of a conventional display device. 
         FIG.  5    is a cross-sectional view showing a configuration example of a display device according to Modification Example 1. 
         FIG.  6    is a cross-sectional view showing a first configuration example of a display device according to Modification Example 2. 
         FIG.  7    is a cross-sectional view showing a second configuration example of the display device according to Modification Example 2. 
         FIG.  8    is a plan view showing a configuration example of a display device according to Modification Example 3. 
         FIG.  9    is a cross-sectional view showing a first configuration example of a step. 
         FIG.  10    is a cross-sectional view showing a second configuration example of a step. 
         FIG.  11    is a cross-sectional view showing a configuration example of a display device according to Modification Example 4. 
         FIG.  12 A  is a front view showing an example of the appearance of a digital still camera.  FIG.  12 B  is a rear view showing an example of the appearance of the digital still camera. 
         FIG.  13    is a perspective view of an example of the appearance of a head-mounted display. 
         FIG.  14    is a perspective view showing an example of the appearance of a television device. 
         FIG.  15    is a perspective view showing an example of the appearance of a lighting device. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present disclosure will be described in the following order. 
     In addition, in all drawings of the following embodiments, the same or corresponding parts are denoted by the same reference numerals. 
     1 Configuration of display device
 
2 Manufacturing method of display device
 
3 Operation and effect
 
     4 Modification Example 
     5 Application Example 
     1 CONFIGURATION OF DISPLAY DEVICE 
       FIG.  1    is a plan view showing a configuration example of an organic EL (Electroluminescence) display device  10  (hereinafter simply referred to as “display device  10 ”) according to an embodiment of the present disclosure.  FIG.  2    is a cross-sectional view taken along line II-II of  FIG.  1   . The display device  10  includes a drive substrate  11 , a plurality of light-emitting elements  12 , a contact portion  13 , a pad portion  14 , an insulating layer  15 , a protective layer  16 , a color filter  17 , a filling resin layer  18 , and a counter substrate  19 . 
     The display device  10  is an example of a light-emitting device. The display device  10  is a top-emission-type display device. The drive substrate  11  constitutes the display surface side of the display device  10 , and the counter substrate  19  constitutes the rear surface side of the display device  10 . The counter substrate  19  side is the top side, and the substrate  11 A side is the bottom side. In the following description, in each layer constituting the display device  10 , the surface on the display surface side of the display device  10  is referred to as a first surface, and the surface on the rear surface side of the display device  10  is referred to as a second surface. 
     The display device  10  has an element formation region R 1  and a peripheral region R 2 . The element formation region R 1  is a region in which a plurality of light-emitting elements  12  are formed. The peripheral region R 2  is a region provided around the element formation region R 1 . The peripheral region R 2  has a closed loop shape surrounding the element formation region R 1 . 
     The display device  10  may be a microdisplay. The display device  10  may be used in various electronic apparatuses. Electronic apparatuses using the display device  10  include, for example, display devices for VR (Virtual Reality), MR (Mixed Reality), and AR (Augmented Reality), and an electronic view finder (EVF), a small projector, and the like. 
     (Substrate) 
     The drive substrate  11  is a so-called backplane and drives the plurality of light-emitting elements  12 . The drive substrate  11  includes a substrate  11 A and an insulating layer  11 B. 
     On the first surface of the substrate  11 A, there are provided a drive circuit including sampling transistors and driving transistors for controlling driving of the plurality of light-emitting elements  12 , a power supply circuit for supplying power to the plurality of light-emitting elements  12 , an underlying wiring, and the like (neither of which are shown). The drive circuit and the power supply circuit are disposed, for example, in the element formation region R 1 . The underlying wiring is disposed, for example, in the peripheral region R 2 . 
     The substrate  11 A may be made of, for example, glass or resin having low moisture and oxygen permeability, or may be made of a semiconductor that facilitates the formation of transistors and the like. Specifically, the substrate  11 A may be a glass substrate, a semiconductor substrate, a resin substrate, or the like. Glass substrates include, for example, high strain-point glass, soda glass, borosilicate glass, forsterite, lead glass, or quartz glass. Semiconductor substrates include, for example, amorphous silicon, polycrystalline silicon, monocrystalline silicon, or the like. The resin substrates include, for example, at least one selected from the group consisting of polymethyl methacrylate, polyvinyl alcohol, polyvinyl phenol, polyethersulfone, polyimide, polycarbonate, polyethylene terephthalate and polyethylene naphthalate. 
     The insulating layer  11 B is provided on the first surface of the substrate  11 A and covers the drive circuit, the power supply circuit, the underlying wiring, and the like. The insulating layer  11 B has a plurality of first contact plugs (not shown). The first contact plug connects the first electrode  12 A forming the light-emitting element  12  and the drive circuit. The insulating layer  11 B further includes one or more second contact plugs (not shown). The second contact plug connects the contact portion  13  and the underlying wiring. 
     The insulating layer  11 B is made of, for example, an organic material or an inorganic material. The organic material includes, for example, at least one of polyimide and acrylic resin. The inorganic material includes, for example, at least one of silicon oxide, silicon nitride, silicon oxynitride, and aluminum oxide. 
     (Light-Emitting Element) 
     A plurality of light-emitting elements  12  are provided in the element formation region R 1  on the first surface of the drive substrate  11 . The plurality of light-emitting elements  12  are, for example, two-dimensionally arranged in a prescribed arrangement pattern such as a matrix in the element formation region R 1 . The light-emitting element  12  is configured to emit white light. The light-emitting element  12  is, for example, a white OLED or a white micro-OLED (MOLED). In the present embodiment, a method using the light-emitting element  12  and the color filter  17  is used as a method for colorization in the display device  10 . However, the colorization method is not limited to this, and an RGB coloring method or the like may be used. Also, instead of the color filter  17 , a monochromatic filter may be used. 
     The light-emitting element  12  includes a first electrode  12 A, an organic layer  12 B, and a second electrode  12 C. The first electrode  12 A, the organic layer  12 B, and the second electrode  12 C are laminated in this order from the drive substrate  11  side toward the counter substrate  19 . 
     (First Electrode) 
     The first electrode  12 A is provided on the first surface of the drive substrate  11 . The first electrode  12 A is electrically separated for each sub-pixel. The first electrode  12 A is the anode. The first electrode  12 A also functions as a reflective layer, and is preferably made of a material having a reflectance as high as possible and a work function as large as possible in order to increase the luminous efficiency. 
     The first electrode  12 A is configured of at least one layer of a metal layer  12 A 1  and a metal oxide layer  12 A 2 . More specifically, the first electrode  12 A is configured of a single layer film of the metal layer  12 A 1  or the metal oxide layer  12 A 2 , or a laminated film of the metal layer  12 A 1  and the metal oxide layer  12 A 2 . Note that  FIG.  2    shows an example in which the first electrode  12 A is configured of a laminated film. When the first electrode  12 A is configured of a laminated film, the metal oxide layer  12 A 2  may be provided on the organic layer  12 B side, and the metal layer  12 A 1  may be provided on the organic layer  12 B side. From the viewpoint of placing a layer having a high work function adjacent to the organic layer  12 B, it is preferable that the metal oxide layer  12 A 2  is provided on the organic layer  12 B side. 
     The metal layer  12 A 1  is made of, for example, at least one metal element selected from the group consisting of chromium (Cr), gold (Au), platinum (Pt), nickel (Ni), copper (Cu), molybdenum (Mo), titanium (Ti), tantalum (Ta), aluminum (Al), magnesium (Mg), iron (Fe), tungsten (W), and silver (Ag). The metal layer  12 A 1  may contain the at least one metal element as a constituent element of an alloy. Specific examples of alloys include aluminum alloys and silver alloys. Specific examples of aluminum alloys include AlNd and AlCu. 
     The metal oxide layer  12 A 2  includes, for example, at least one of a mixture of indium oxide and tin oxide (ITO), a mixture of indium oxide and zinc oxide (IZO), and titanium oxide (TiO). 
     (Second Electrode) 
     The second electrode  12 C is provided so as to face the first electrode  12 A. The second electrode  12 C is provided as a common electrode for all sub-pixels within the element formation region R 1 . The second electrode  12 C is the cathode. The second electrode  12 C is a transparent electrode that is transparent to the light generated in the organic layer  12 B. Here, the transparent electrode includes a semi-transmissive reflective layer. The second electrode  12 C is preferably made of a material having a transmittance as high as possible and a work function as small as possible in order to increase the luminous efficiency. 
     The second electrode  12 C is configured of at least one layer of a metal layer and a metal oxide layer. More specifically, the second electrode  12 C is configured of a single layer film of a metal layer or a metal oxide layer, or a laminated film of a metal layer and a metal oxide layer. When the second electrode  12 C is configured of a laminated film, the metal layer may be provided on the organic layer  12 B side, and the metal oxide layer may be provided on the organic layer  12 B side. From the viewpoint of placing a layer having a low work function adjacent to the organic layer  12 B, it is preferable that the second electrode  12 C is provided on the organic layer  12 B side. 
     The metal layer contains, for example, at least one metal element selected from the group consisting of magnesium (Mg), aluminum (Al), silver (Ag), calcium (Ca) and sodium (Na). The metal layer may contain the at least one metal element as a constituent element of an alloy. Specific examples of alloys include MgAg alloys, MgAl alloys, AILi alloys, and the like. Metal oxides include, for example, at least one of a mixture of indium oxide and tin oxide (ITO), a mixture of indium oxide and zinc oxide (IZO), and zinc oxide (ZnO). 
     (Organic Layer) 
     The organic layer  12 B is provided between the first electrode  12 A and the second electrode  12 C. The organic layer  12 B is provided as an organic layer common for all sub-pixels within the element formation region R 1 . The organic layer  12 B is configured to emit white light. 
     The organic layer  12 B has a configuration in which a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are laminated in this order from the first electrode  12 A toward the second electrode  12 C. Note that the configuration of the organic layer  12 B is not limited to this, and layers other than the light-emitting layer are provided as necessary. 
     The hole injection layer is a buffer layer for increasing the efficiency of hole injection into the light-emitting layer and suppressing leakage. The hole transport layer is for increasing the efficiency of transporting holes to the light-emitting layer. In the light-emitting layer, recombination of electrons and holes occurs when an electric field is applied to generate light. The light-emitting layer is an organic light-emitting layer containing an organic light-emitting material. The electron transport layer is for enhancing the efficiency of transporting electrons to the light-emitting layer. An electron injection layer may be provided between the electron transport layer and the second electrode  12 C. This electron injection layer is for enhancing the electron injection efficiency. 
     (Contact Portion) 
     The contact portion  13  is an auxiliary electrode that connects the second electrode  12 C and an underlying wiring (not shown). A first surface of the contact portion  13  is connected to a peripheral portion  12 CA of the second electrode  12 C. On the other hand, the second surface of the contact portion  13  is connected to the underlying wiring through a contact plug. In this specification, the peripheral portion  12 CA of the second electrode  12 C refers to a region having a predetermined width toward the inner side from the peripheral edge of the second electrode  12 C. 
       FIG.  3    is an enlarged plan view showing a portion of the display device  10 . The contact portion  13  is provided in the peripheral region R 2  on the first surface of the drive substrate  11 . As shown in  FIG.  3   , the contact portion  13  has a rectangular closed loop shape surrounding the rectangular element formation region R 1 . That is, the contact portion  13  has a corner portion. 
     The contact portion  13  is configured of at least one of the metal layer  13 A and the metal oxide layer  13 B. More specifically, the contact portion  13  is configured of a single layer film of the metal layer  13 A or the metal oxide layer  13 B, or a laminated film of the metal layer  13 A and the metal oxide layer  13 B. Note that  FIG.  2    shows an example in which the contact portion  13  is formed of a laminated film. When the contact portion  13  is configured of a laminated film, the metal oxide layer  13 B may be provided on the second electrode  12 C side, and the metal layer  13 A may be provided on the second electrode  12 C side. 
     As a constituent material of the contact portion  13 , the same material as that of the above-described first electrode  12 A can be exemplified. Specifically, as the constituent materials of the metal layer  13 A and the metal oxide layer  13 B of the contact portion  13 , the same materials as those of the metal layer  12 A 1  and the metal oxide layer  12 A 2  of the first electrode  12 A can be exemplified. 
     The contact portion  13  may have the same configuration as the first electrode  12 A. The metal layer  13 A and the metal oxide layer  13 B of the contact portion  13  may have the same configurations as the metal layer  12 A 1  and the metal oxide layer  12 A 2  of the first electrode  12 A, respectively. 
     (Insulating Layer) 
     The insulating layer  15  is provided in the element formation region R 1  and the peripheral region R 2  on the first surface of the drive substrate  11 . The insulating layer  15  electrically separates the respective first electrodes  12 A for each light-emitting element  12  (that is, for each sub-pixel) in the element formation region R 1 . The insulating layer  15  has a plurality of first openings  15 A, and the first surfaces of the separated first electrodes  12 A (surfaces facing the second electrodes  12 C) are exposed through the first openings  15 A. The insulating layer  15  may cover the peripheral portion of the first surface of the separated first electrode  12 A to the side surface (end surface). In this specification, the peripheral portion of the first surface refers to a region having a predetermined width toward the inner side from the peripheral edge of the first surface. 
     The insulating layer  15  electrically separates the respective light-emitting elements  12  located in the peripheral portion of the element formation region R 1  from the contact portion  13  provided in the peripheral region R 2 . The insulating layer  15  has a second opening  15 B, and the first surface of the contact portion  13  is exposed through the second opening  15 B. The second opening  15 B has, for example, a closed loop shape. The insulating layer  15  may cover the peripheral portion of the first surface of the contact portion  13  to the side surface (end surface) of the contact portion  13 . 
     The insulating layer  15  electrically separates the contact portion  13  and the pad portion  14  provided in the peripheral region R 2 . The insulating layer  15  has a third opening  15 C, and the contact portion  13  is exposed through the third opening  15 C. 
     The insulating layer  15  has a step  15 ST in the peripheral region R 2 . Specifically, the insulating layer  15  has a step  15 ST on the first surface of the contact portion  13 . The step  15 ST extends in the circumferential direction of the peripheral region R 2 . The step  15 ST rises in the direction from the inner side of the display device  10  to the outer circumference side. The peripheral edge of the second electrode  12 C is provided in the vicinity of the step  15 ST on the side closer to the element formation region R 1  than the step  15 ST. Accordingly, it is possible to suppress the occurrence of a step in the peripheral region R 2  due to the side surface (end surface) of the second electrode  12 C. Therefore, it is possible to suppress the occurrence of cracks in the protective layer  16  in the peripheral region R 2 . In the present disclosure, the crack may be a crack that occurs when the protective layer  16  is formed by chemical vapor deposition, physical vapor deposition, or the like (for example, CVD), or may be a crack that occurs due to stress acting on the protective layer  16  after the protective layer  16  is formed. 
     From the viewpoint of suppressing the occurrence of cracks, the distance D1 between the step  15 ST and the peripheral edge of the second electrode  12 C in the in-plane direction of the display surface is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 2 μm or less, and particularly preferably 1 μm or less. 
     From the viewpoint of suppressing the occurrence of cracks, the height of the step  15 ST is preferably substantially equal to the height of the side surface of the second electrode  12 C. In the present embodiment, the side surface of the second electrode  12 C is located on the contact portion  13 . 
     In the present embodiment, the step  15 ST is a step between the first surface of the contact portion  13  and the first surface of the insulating layer  15 . That is, the step  15 ST is formed by the inner wall of the second opening  15 B. As a constituent material of the insulating layer  15 , the same material as that of the insulating layer  11 B described above can be exemplified. 
     (Protective Layer) 
     The protective layer  16  is provided on the first surface of the second electrode  12 C and covers the light-emitting element  12 , the peripheral portion  12 CA of the second electrode  12 C, the contact portion  13 , the insulating layer  15 , and the like. The protective layer  16  shields the light-emitting element  12 , the peripheral portion  12 CA of the second electrode  12 C, the contact portion  13 , and the like from the outside air, and suppresses moisture from entering the light-emitting element  12 , the peripheral portion  12 CA of the second electrode  12 C, the contact portion  13 , and the like from the external environment. Moreover, when the second electrode  12 C is configured of a metal layer, the protective layer  16  may have a function of suppressing oxidation of this metal layer. 
     From the viewpoint of narrowing the frame of the display device  10 , the distance D2 between the peripheral edge of the protective layer  16  and the peripheral edge of the second electrode  12 C in the in-plane direction of the display surface is preferably 10 μm or less, more preferably 5 μm or less, even more preferably 2 μm or less, and particularly preferably 1 μm or less. In the display device  10  according to an embodiment, even when the frame is narrowed so that the distance D2 is 10 μm or less, it is possible to suppress one end of a crack occurred in the peripheral region R 2  of the display device  10  from reaching the side surface (end surface) of the protective layer  16 . In the display device  110  having the conventional configuration, if the frame is narrowed so that the distance D2 is 10 μm or less, one end of the crack  16 A easily reaches the side surface (end surface) of the protective layer  16  (see  FIG.  4   ). 
     The protective layer  16  is made of, for example, an inorganic material. As the inorganic material constituting the protective layer  16 , one having low hygroscopicity is preferable. Specifically, the inorganic material constituting the protective layer  16  preferably includes at least one selected from the group consisting of silicon oxide (SiO), silicon nitride (SiN), silicon oxynitride (SiNO), titanium oxide (TiO) and aluminum oxide (AlO). The protective layer  16  may have a single-layer structure, but may have a multi-layer structure when the thickness is increased. This is for alleviating the internal stress in the protective layer  16 . 
     (Color Filter) 
     The color filter  17  is provided on the protective layer  16 . The color filter  17  is, for example, an on-chip color filter (OCCF). The color filter  17  includes, for example, a red filter, a green filter and a blue filter. A red filter, a green filter, and a blue filter are provided so as to face the light-emitting element  12  for the red sub-pixel, the light-emitting element  12  for the green sub-pixel, and the light-emitting element  12  for the blue sub-pixel, respectively. As a result, white light emitted from each light-emitting element  12  in the red sub-pixel, green sub-pixel, and blue sub-pixel passes through the red filter, green filter, and blue filter, respectively, whereby red light, green light, and blue light are emitted from the display surface. A light-shielding layer (not shown) may be provided between the color filters of each color, that is, between the sub-pixels. Note that the color filters  17  are not limited to on-chip color filters, and may be provided on one main surface of the counter substrate  19 . 
     (Filling Resin Layer) 
     The filling resin layer  18  is provided between the color filter  17  and the counter substrate  19 . The filling resin layer  18  functions as an adhesive layer that bonds the color filter  17  and the counter substrate  19  together. The filling resin layer  18  contains, for example, at least one of a thermosetting resin and an ultraviolet curable resin. 
     (Counter Substrate) 
     The counter substrate  19  is provided so as to face the drive substrate  11 . More specifically, the counter substrate  19  is provided such that the second surface of the counter substrate  19  and the first surface of the drive substrate  11  face each other. The counter substrate  19  and the filling resin layer  18  seal the light-emitting element  12 , the color filter  17 , the contact portion  13 , and the like. The counter substrate  19  is made of a material such as glass that is transparent to each color of light emitted from the color filters  17 . 
     (Pad Portion) 
     The pad portion  14  is a connection portion for electrically connecting the display device  10  to an electronic apparatus or the like. The pad portion  14  is provided with a plurality of connection terminals  14 A. The pad portion  14  is connected to a main board or the like of the electronic apparatus via a connection member such as a flexible printed wiring board. 
     2 MANUFACTURING METHOD OF DISPLAY DEVICE 
     An example of a method for manufacturing the display device  10  according to an embodiment of the present disclosure will be described below. In this manufacturing method, a case where the first electrode  12 A and the contact portion  13  have the same configuration (that is, the laminated film of the metal layer  12 A 1  and the metal oxide layer  12 A 2 ) will be described. However, the first electrode  12 A and the contact portion  13  may have different configurations. 
     First, a drive circuit, a power supply circuit, an underlying wiring, and the like are formed on the first surface of the substrate  11 A using, for example, thin film formation technology, photolithography technology, and etching technology. Next, the insulating layer  11 B is formed on the first surface of the substrate  11 A so as to cover the drive circuit, the power supply circuit, the underlying wiring, and the like by, for example, the CVD method. After that, a plurality of first contact plugs, one or a plurality of second contact plugs, and the like are formed on the insulating layer  11 B. In this way, the drive substrate  11  is formed. 
     Next, after forming a laminated film of the metal layer  12 A 1  and the metal oxide layer  12 A 2  on the first surface of the drive substrate  11  by, for example, sputtering, the laminated film is patterned by, for example, photolithography technology and etching technology. Thus, the first electrodes  12 A and the contact portions  13  separated for each light-emitting element  12  (that is, for each sub-pixel) are formed. 
     Next, the insulating layer  15  is formed on the first surface of the drive substrate  11  so as to cover the plurality of first electrodes  12 A and the contact portions  13  by, for example, the CVD method, and then the insulating layer  15  is patterned using a photolithography technology and an etching technology. In this way, a plurality of first openings  15 A, second openings  15 B, and third openings  15 C are formed in the insulating layer  15 . 
     Next, a hole injection layer, a hole transport layer, a light-emitting layer, and an electron transport layer are laminated in this order on the first surface of the first electrode  12 A and the first surface of the insulating layer  15  by a vapor deposition method, for example. By doing so, the organic layer  12 B is formed. Next, the second electrode  12 C is formed on the first surfaces of the organic layer  12 B and the contact portion  13  by, for example, a vapor deposition method or a sputtering method. As a result, a plurality of light-emitting elements  12  are formed on the first surface of the drive substrate  11 , and the peripheral portion  12 CA of the second electrode  12 C is joined to the contact portion  13 . 
     Next, after forming the protective layer  16  on the first surface of the second electrode  12 C by, for example, a CVD method or a vapor deposition method, the color filter  17  is formed on the first surface of the protective layer  16  by, for example, photolithography. A planarization layer may be formed above, below, or both above and below the color filter  17  in order to planarize the step of the protective layer  16  and the step due to the film thickness difference of the color filter  17  itself. Next, after the color filters  17  are covered with the filling resin layer  18  using, for example, the ODF (One Drop Fill) method, the counter substrate  19  is placed on the filling resin layer  18 . Next, for example, by applying heat to the filling resin layer  18  or irradiating the filling resin layer  18  with ultraviolet rays to harden the filling resin layer  18 , the drive substrate  11  and the counter substrate  19  are bonded together via the filling resin layer  18 . In this way, the display device  10  is sealed. As described above, the display device  10  shown in  FIGS.  1  and  2    is obtained. 
     3 OPERATION AND EFFECT 
       FIG.  4    is a cross-sectional view showing the configuration of a display device  110  according to a conventional example. In the display device  110  according to the conventional example, the peripheral edge of the second electrode  12 C is provided over the step  15 ST. Therefore, a step  12 ST is formed in the vicinity of the side surface (end surface) of the protective layer  16  by the side surface (end surface) of the second electrode  12 C. Therefore, when the protective layer  16  is formed by chemical vapor deposition or physical vapor deposition (for example, CVD), a crack  16 A may occur from the steps  12 ST toward the side surfaces of the protective layer  16 . Moreover, there is a possibility that the crack  16 A may occur due to the stress acting on the protective layer  16  after the protective layer  16  is formed. Therefore, the reliability of the display device  110  deteriorates. 
     When the frame of the display device  110  according to the conventional example is narrowed (for example, D2&lt;10 μm), the distance from the step  12 ST to the side surface of the protective layer  16  becomes short. Thus, the crack  16 A becomes particularly easy to reach the side surface of the protective layer  16  from the step  12 ST. Therefore, when the frame of the display device  110  according to the conventional example is narrowed, the reliability is particularly likely to deteriorate. 
     Incidentally, as shown in  FIG.  4   , a crack  16 B may occur from the vicinity of the step  15 ST toward the first surface of the protective layer  16 . However, since the crack  16 B is not electrically connected to the outside of the display device  10 , the influence of the crack  16 B on the reliability of the display device  110  is much less than the influence of the crack  16 A on the reliability of the display device  110 . 
     In contrast, as described above, in the display device  10  according to an embodiment, the peripheral edge of the second electrode  12 C is provided in the vicinity of the step  15 ST on the side closer to the element formation region R 1  than the step  15 ST. In this way, it is possible to suppress the formation of the step  12 ST (see  FIG.  4   ) in the vicinity of the peripheral edge (side surface) of the protective layer  16 . Therefore, when the protective layer  16  is formed by chemical vapor deposition, physical vapor deposition, or the like (for example, CVD), it is possible to suppress a crack  16 A (see  FIG.  4   ) from occurring from the side surface of the second electrode  12 C toward the side surface of the protective layer  16 . Also, it is possible to suppress the crack  16 A from occurring due to the stress acting on the protective layer  16  after the protective layer  16  is formed. Therefore, deterioration in reliability of the display device  10  can be suppressed. Such an effect of suppressing reliability deterioration becomes remarkable in the display device  10  having a narrow frame (for example, D2&lt;10 μm). 
     4 MODIFICATION EXAMPLE 
     Modification Example 1 
     In the above-described embodiment, an example in which the peripheral edge of the second electrode  12 C is provided in the vicinity of the step  15 ST on the side closer to the element formation region R 1  than the step  15 ST has been described. However, as shown in  FIG.  5   , the peripheral edge of the second electrode  12 C may be provided away from the step  15 ST on the side closer to the element formation region R 1  than the step  15 ST. Specifically, for example, the distance D1 between the step  15 ST and the peripheral edge of the second electrode  12 C in the in-plane direction of the display surface may exceed 10 μm. In this case, a recess may be formed on the first surface of the contact portion  13  by the step  15 ST and the side surface of the second electrode  12 C. 
     In the display device  10  according to Modification Example 1, cracks  16 C generated from the step  15 ST and the side surfaces (end surfaces) of the second electrode  12 C during or after the formation of the protective layer  16  meet at a position between the step  15 ST and the second electrode  12 C and extend from the second surface of the protective layer  16  toward the first surface. Therefore, it is possible to suppress the occurrence of cracks  16 A (see  FIG.  4   ) extending from the inside of the protective layer  16  toward the side surface of the protective layer  16 . Therefore, deterioration in reliability of the display device  10  can be suppressed. As described above, the influence of the crack  16 C that is not electrically connected to the outside on the reliability of the display device  10  is much smaller than the influence of the crack  16 A that is electrically connected to the outside on the reliability of the display device  110 . 
     Modification Example 2 
     In the above-described embodiment, an example in which the height of the step  15 ST is substantially equal to the height of the side surface of the second electrode  12 C has been described. However, the height of the step  15 ST may be higher than the height of the side surface of the second electrode  12 C as shown in  FIG.  6   . In this case, a crack  16 D generated during or after the formation of the protective layer  16  extends from the step  12 ST in a direction inclined toward the element formation region R 1  with respect to the thickness direction of the protective layer  16 . Thus, the crack  16 D is not electrically connected to the outside of the display device  10  through the side surface of the protective layer  16 . Therefore, it is possible to prevent moisture or the like from entering the display device  10  from the outside. Therefore, deterioration in reliability of the display device  10  can be suppressed. Here, the height of the step  15 ST and the height of the side surface of the second electrode  12 C mean the height from the first surface of the contact portion  13  as a reference. 
     As shown in  FIG.  7   , the height of the side surface of the second electrode  12 C may be higher than the height of the step  15 ST. In this case, a crack  16 E generated during or after the protective layer  16  is formed extends from the side surface (end surface) of the second electrode  12 C in a direction inclined toward the outer circumference side of the display device  10  with respect to the thickness direction of the protective layer  16 . In the display device  10  according to Modification Example 2, the peripheral edge of the second electrode  12 C is provided closer to the element formation region R 1  than the step  15 ST. Thus, the distance between the peripheral edge of the second electrode  12 C and the peripheral edge of the protective layer  16  is increased as compared to the conventional display device  110  (see  FIG.  4   ). Therefore, even if the crack  16 E extends in a direction inclined toward the outer circumference side as described above, the crack  16 E is prevented from reaching the side surface of the protective layer  16 . 
     Further, when the peripheral edge of the second electrode  12 C is in the vicinity of the step  15 ST on the side closer to the element formation region R 1  than the step  15 ST, the step substantially formed by the side surface of the second electrode  12 C is lowered by the height of  15 ST (that is, by the thickness of the insulating layer  15  on the contact portion  13 ). Therefore, the step substantially formed in the peripheral region R 2  by the second electrode  12 C is lower than that when the second electrode  12 C is provided over the step  15 ST (see  FIG.  4   ). 
     Therefore, even in the case of the configuration shown in  FIG.  7   , it is possible to suppress deterioration in the reliability of the display device  10 . 
     Modification Example 3 
     In the above-described embodiment, an example in which the contact portion  13  has a closed loop shape surrounding the peripheral edge of the element formation region R 1  has been described. However, as shown in  FIG.  8   , the contact portion  13  may be provided so as to face a portion (first portion) of the outer circumference of the element formation region R 1 . Specifically, the peripheral region R 2  may have a first peripheral region RA which is provided so as to face a portion (first portion) of the outer circumference of the element formation region R 1 , and in which the contact portion  13  is formed, and a second peripheral region RB which is provided so as to face another portion (second portion) of the outer circumference of the element formation region R 1  and in which the contact portion  13  is not formed. In the display device  10  having such a configuration, the area of the element formation region R 1  can be made larger than that in the display device  10  according to the above-described embodiment. That is, it is possible to increase the area of the effective display region. The second peripheral region RB is preferably provided to face the long side or short side of the rectangular element formation region R 1 . 
     As shown in  FIG.  9   , a step  15 STa may be provided in the second peripheral region RB. The step  15 STa extends in the circumferential direction of the peripheral region R 2 . Like the step  15 ST, the step  15 STa rises in the direction from the inner side of the display device  10  to the outer circumference side. The peripheral edge of the second electrode  12 C is preferably provided in the vicinity of the step  15 STa on the side closer to the element formation region R 1  than the step  15 STa. In this way, it is possible to suppress the occurrence of cracks  16 A in the protective layer  16  in both the first peripheral region RA and the second peripheral region RB. 
     As shown in  FIG.  9   , the insulating layer  15  may have, on its first surface, a recess  15 D provided so as to face another portion (second portion) of the outer circumference of the element formation region R 1 , and a step  15 STa may be formed by the side wall on the outer circumference side of the recess  15 D. The recess  15 D may be connected to a second opening  15 B formed on the first surface of contact portion  13 . The step  15 ST and the step  15 STa may be flush with each other. The first surface of the contact portion  13  and the bottom surface of the recess  15 D may be at the same height. The step  15 ST and the step  15 STa may be at the same height. 
     As shown in  FIG.  10   , in the second peripheral region RB, the insulating layer  15  may have a protrusion  15 E on the side closer to the outer circumference side of the display device  10  than the peripheral edge of the second electrode  12 C, and the step  15 STa may be formed by the protrusion  15 E. 
     The positional relationship between the peripheral edge of the second electrode  12 C and the step  15 ST in the first peripheral region RA and the positional relationship between the peripheral edge of the second electrode  12 C and the step  15 STa in the second peripheral region RB may be the same as the positional relationship between the peripheral edge of the second electrode  12 C and the step  15 ST in Modification Example 1 described above. 
     The relationship between the side surface of the second electrode  12 C and the height of the step  15 ST in the first peripheral region RA and the relationship between the side surface of the second electrode  12 C and the height of the step  15 STa in the second peripheral region RB may be the same as the relationship between the side surface of the second electrode  12 C and the height of the step  15 ST in Modification Example 2 described above. 
     Modification Example 4 
     In the above-described embodiment, an example in which the display device  10  includes the contact portion  13  in the peripheral region R 2  has been described, but the contact portion  13  may not be provided in the peripheral region R 2 . In this case, the configuration of the step  15 ST in the peripheral region R 2  may be the same as the configuration of the step  15 STa in Modification Example 3 described above. 
     Modification Example 5 
     In the above-described embodiment, an example in which the corners of the contact portion  13  are formed by two orthogonal straight lines (see  FIG.  3   ) has been described, but the corners of the contact portion  13  may be curved as shown in  FIG.  11   . That is, the inner circumference and the outer circumference of the contact portion  13  may be curved. Specifically, the corners of the inner circumference of the contact portion  13  may be curved in a concave shape, and the corners of the outer circumference of the contact portion  13  may be curved in a convex shape. 
     The corners of the second electrode  12 C may be curved similarly to the contact portion  13  to form a curved shape. That is, the outer circumference of the second electrode  12 C may be curved in a convex shape. 
     As shown in  FIG.  3   , if the corners of the contact portion  13  are formed by two orthogonal straight lines, film stress concentrates on the corners and cracks are likely to occur. On the other hand, if the corners of the contact portion  13  are curved as described above, it is possible to suppress the film stress from concentrating on the corners. 
     5 APPLICATION EXAMPLE 
     (Electronic Apparatus) 
     The display device  10  according to the above-mentioned embodiment and modification examples may be provided in various electronic apparatuses. In particular, it is preferable provided in an apparatus such as an electronic viewfinder or a head-mounted display of a video camera or a single-lens reflex camera, which requires a high resolution and is used in a magnified manner near the eyes. 
     Specific Example 1 
       FIG.  12 A  is a front view showing an example of the appearance of a digital still camera  310 .  FIG.  12 B  is a rear view showing an example of the appearance of the digital still camera  310 . This digital still camera  310  is an interchangeable single-lens reflex-type camera, and has an interchangeable photographing lens unit (interchangeable lens)  312  in approximately the center of the front surface of a camera main body (camera body)  311 , and has a grip portion  313  for a photographer to hold on the left side of the front surface. 
     A monitor  314  is provided at a position shifted to the left from the center of the rear surface of the camera body  311 . An electronic viewfinder (eyepiece window)  315  is provided above the monitor  314 . By looking through the electronic viewfinder  315 , the photographer can view the optical image of a subject guided from the photographing lens unit  312  and determine the composition. As the electronic viewfinder  315 , any one of the display devices  10  according to the above-described embodiment and modification examples can be used. 
     Specific Example 2 
       FIG.  13    is a perspective view showing an example of the appearance of a head-mounted display  320 . The head-mounted display  320  has, for example, ear hooks  322  on both sides of an eyeglass-shaped display  321  to be worn on the user&#39;s head. As the display unit  321 , any one of the display devices  10  according to the above-described embodiment and modification examples can be used. 
     Specific Example 3 
       FIG.  14    is a perspective view showing an example of the appearance of a television device  330 . This television device  330  has, for example, an image display screen portion  331  including a front panel  332  and a filter glass  333 . This image display screen portion  331  is configured of any one of the display devices  10  according to the above-described embodiment and modification examples. 
     (Lighting Device) 
     Although an example in which the present disclosure is applied to a display device has been described in the above-described embodiment, the present disclosure is not limited to this, and the present disclosure may be applied to a lighting device. A lighting device is an example of a light-emitting device. 
       FIG.  15    is a perspective view showing an example of the appearance of a stand-type lighting device  400 . This lighting device  400  has a lighting unit  413  attached to a post  412  provided on a base  411 . As the lighting unit  413 , the display device  10  according to any one of the above-described embodiment and modification examples, which is provided with a drive circuit for the lighting device instead of the drive circuit for the display device is used. Moreover, the color filter  17  may be omitted, and the size of the light-emitting element  12  may be appropriately selected according to the optical characteristics of the lighting device  400  and the like. Furthermore, by using a film as the substrate  11 A and the counter substrate  19  and having a flexible configuration, it is possible to form any shape such as a cylindrical shape or a curved shape shown in  FIG.  15   . Note that the number of light-emitting elements  12  may be singular. Also, a monochromatic filter may be provided instead of the color filter  17 . 
     Here, a case where the lighting device is the stand-type lighting device  400  has been described, but the form of the lighting device is not limited to this. For example, the lighting device may be installed on the ceiling, wall, floor, or the like. 
     While an embodiment of the present disclosure and its modification examples have been described above in detail, the present disclosure is not limited to the embodiment and its modification examples, and various modifications based on the technical idea of the present disclosure can be made. 
     For example, the configurations, methods, processes, shapes, materials, numerical values, and the like exemplified in the embodiment and its modification examples are only examples, and as necessary, different configurations, methods, processes, shapes, materials, numerical values, and the like may be used. 
     The configurations, methods, processes, shapes, materials, numerical values, and the like of the embodiment and its modification examples can be combined with each other as long as they do not deviate from the gist of the present disclosure. 
     Unless otherwise specified, the materials exemplified in the embodiment and its modification examples may be used alone or two or more thereof may be used in combination. 
     In addition, the present disclosure can also adopt the following configurations. 
     (1) A display device including:
 
a plurality of light-emitting elements;
 
a contact portion provided around a region in which the plurality of light-emitting elements are formed;
 
an insulating layer having a step on the contact portion; and
 
a protective layer covering the light-emitting elements, the contact portion, and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral portion connected to the contact portion; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the display device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
(2) The display device according to (1), wherein
 
the insulating layer has an opening that exposes the contact portion, and
 
the step is formed by an inner wall of the opening.
 
(3) The display device according to (1) or (2), wherein
 
the peripheral edge of the second electrode is provided in the vicinity of the step.
 
(4) The display device according to any one of (1) to (3), wherein
 
a distance between the step and the peripheral edge of the second electrode is 10 μm or less.
 
(5) The display device according to any one of (1) to (3), wherein
 
a distance between the step and the peripheral edge of the second electrode exceeds 10 μm.
 
(6) The display device according to any one of (1) to (3), wherein
 
a distance between a peripheral edge of the protective layer and the peripheral edge of the second electrode is 10 μm or less.
 
(7) The display device according to any one of (1) to (6), wherein
 
a height of the step is approximately equal to a height of a side surface of the second electrode.
 
(8) The display device according to any one of (1) to (6), wherein
 
a height of the step is higher than a height of a side surface of the second electrode.
 
(9) The display device according to any one of (1) to (6), wherein
 
a height of a side surface of the second electrode is higher than a height of the step.
 
(10) The display device according to any one of (1) to (9), wherein the contact portion has a closed loop shape surrounding the region.
 
(11) The display device according to any one of (1) to (10), wherein
 
the contact portion is provided so as to face a first portion of an outer circumference of the region.
 
(12) The display device according to (11), wherein
 
the insulating layer has another step provided so as to face a second portion of the outer circumference of the region, and
 
the other step rises from the inner side of the display device toward the outer circumference side.
 
(13) The display device according to (11), wherein
 
the insulating layer has a recess provided so as to face another portion of the outer circumference of the region, and
 
the recess forms a step that rises from the inner side of the display device toward the outer circumference side.
 
(14) The display device according to any one of (1) to (13), wherein
 
corners of the contact portions are curved.
 
(15) The display device according to any one of (1) to (14), wherein
 
the protective layer is made of an inorganic material.
 
(16) A light-emitting device including:
 
a plurality of light-emitting elements;
 
a contact portion provided around a region in which the plurality of light-emitting elements are formed;
 
an insulating layer having a step on the contact portion; and
 
a protective layer covering the light-emitting elements, the contact portion, and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral portion connected to the contact portion; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the light-emitting device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
(17) A display device including:
 
a plurality of light-emitting elements;
 
an insulating layer having a step around a region in which the plurality of light-emitting elements are formed; and
 
a protective layer covering the light-emitting elements and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral edge extending to a periphery of the region; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the display device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
(18) A light-emitting device including:
 
a plurality of light-emitting elements;
 
an insulating layer having a step around a region in which the plurality of light-emitting elements are formed; and
 
a protective layer covering the light-emitting elements and the insulating layer, wherein
 
each of the light-emitting elements includes:
 
a first electrode;
 
a second electrode having a peripheral edge extending to a periphery of the region; and
 
a light-emitting layer disposed between the first electrode and the second electrode, wherein
 
the step rises in a direction from an inner side of the light-emitting device toward an outer circumference side, and
 
a peripheral edge of the second electrode is provided closer to the region than the step.
 
(19) An electronic apparatus including the display device according to any one of (1) to (15) and (17).
 
(20) An electronic apparatus including the light-emitting device according to (16) or (18).
 
     REFERENCE SIGNS LIST 
     
         
           10  Display device (light-emitting device) 
           11  Drive substrate 
           11 A Substrate 
           11 B Insulating layer 
           12 A First electrode 
           12 A 1  Metal layer 
           12 A 2  Metal oxide layer 
           12 B Organic layer 
           12 C Second electrode 
           12 CA Peripheral portion 
           12 ST Steps 
           13  Contact portion 
           13 A Metal layer 
           13 B Metal oxide layer 
           13 A Metal layer 
           13 B Metal oxide layer 
           14  Pad portion 
           15  Insulating layer 
           15 A First opening 
           15 B Second opening 
           15 C Third opening 
           15 D Recess 
           15 E Protrusion 
           15 ST,  15 Sta Step 
           16  Protective layer 
           16 A,  16 B,  16 C,  16 D,  16 E Crack 
           17  Color filter 
           18  Filling resin layer 
           19  Counter substrate 
           310  Digital still camera (electronic apparatus) 
           320  Head-mounted display (electronic apparatus) 
           330  Television device (electronic apparatus) 
           400  Lighting device (light-emitting device) 
         R 1  Element formation region 
         R 2  Peripheral region 
         RA First peripheral region 
         RB Second peripheral region