Patent Publication Number: US-2023157044-A1

Title: Method for producing display device, and display device

Description:
TECHNICAL FIELD 
     The disclosure relates to a method for manufacturing a display device and a display device. 
     BACKGROUND ART 
     In recent years, a variety of flat panel displays have been developed, and in particular, a display device which includes a quantum dot light-emitting diode (QLED) or an organic light-emitting diode (OLED) as an electroluminescent element has attracted attention. 
     PTL 1 relates to a method of patterning an organic compound layer including a light-emitting layer by etching the organic compound layer using a patterned photosensitive resin layer as a mask. 
     PTL 2 relates to a method of patterning a light-emitting layer including quantum dots by forming the light-emitting layer using a patterned photosensitive resin as a template. 
     CITATION LIST 
     Patent Literature 
     
         
         PTL 1: JP 2014-120218 A (published on Jun. 30, 2014) 
         PTL 2: JP 2009-87760 A (published on Apr. 23, 2009) 
       
    
     SUMMARY 
     Technical Problem 
     However, in the known technique as described above, there is a problem in that the number of steps is large because the patterned photosensitive resin not included in the finished product is formed and removed. 
     In light of the above problem, an object of the disclosure is to reduce the number of steps in manufacturing a display device. 
     Solution to Problem 
     In order to solve the above problems, a method for manufacturing a display device according to one aspect of the disclosure is a method for manufacturing the display device including a substrate, a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer, and a second subpixel including a second pixel electrode provided on the substrate, the method including: forming the first charge transport layer on the first pixel electrode and the second pixel electrode; applying a first mixture obtained by mixing the first quantum dots and a photosensitive resin on the first charge transport layer; pattern-exposing the first mixture to cure a portion of the first mixture to be formed into the first light-emitting layer; removing an uncured portion of the first mixture; and etching the first charge transport layer with an etching solution using the first light-emitting layer as a mask, the etching solution being an alkaline solution or an organic solvent. 
     In order to solve the problem described above, a display device according to one aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer including second quantum dots, and a second charge transport layer provided between the second pixel electrode and the second light-emitting layer and having the same polarity as the first charge transport layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third charge transport layer provided between the third pixel electrode and the third light-emitting layer and having the same polarity as the first charge transport layer, the third subpixel being adjacent to the first subpixel, in which the first charge transport layer, the second charge transport layer, and the third charge transport layer are soluble in an etching solution that is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first charge transport layer, the second light-emitting layer is in direct contact with the second charge transport layer, the third light-emitting layer is in direct contact with the third charge transport layer, each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer includes a cured photosensitive resin that is insoluble in the etching solution, and the first charge transport layer, the second charge transport layer, and the third charge transport layer are separated from each other. 
     In order to solve the problem described above, a display device according to one aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer including second quantum dots, and a second charge transport layer provided between the second pixel electrode and the second light-emitting layer and having the same polarity as the first charge transport layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third charge transport layer provided between the third pixel electrode and the third light-emitting layer and having the same polarity as the first charge transport layer, the third subpixel being adjacent to the first subpixel, in which the first charge transport layer, the second charge transport layer, and the third charge transport layer are soluble in an etching solution that is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first charge transport layer, the second light-emitting layer is in direct contact with the second charge transport layer, the third light-emitting layer is in direct contact with the third charge transport layer, each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer includes a cured photosensitive resin that is insoluble in the etching solution, a portion of the second charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed therebetween, and a portion of the third charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed therebetween. 
     In order to solve the above problems, a display device according to one aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first portion of a charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer including second quantum dots, and a second portion of the charge transport layer provided between the second pixel electrode and the second light-emitting layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third portion of the charge transport layer provided between the third pixel electrode and the third light-emitting layer, the third subpixel being adjacent to the first subpixel, in which the charge transport layer is soluble in an etching solution that is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first portion of the charge transport layer and includes a cured photosensitive resin that is insoluble in the etching solution, and each of the second and third portions of the charge transport layer is thinner than the first portion of the charge transport layer. 
     Advantageous Effects of Disclosure 
     According to the method for manufacturing a display device and the display device of an aspect of the disclosure, the number of steps in manufacturing a display device can be reduced. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a flowchart illustrating an example of a manufacturing method for a display device. 
         FIG.  2    is a cross-sectional view illustrating an example of a configuration of a display region of the display device. 
         FIG.  3    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a first embodiment of the disclosure. 
         FIG.  4    is a flowchart illustrating an example of a process for forming a light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  5    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  6    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  7    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  8    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  9    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  10    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  11    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  12    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  13    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  14    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  15    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  16    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  17    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  18    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  3   . 
         FIG.  19    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box A in  FIG.  7   . 
         FIG.  20    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box A in  FIG.  8   . 
         FIG.  21    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box A in  FIG.  9   . 
         FIG.  22    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box A in  FIG.  11   . 
         FIG.  23    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box A in  FIG.  12   . 
         FIG.  24    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box Ain  FIG.  13   . 
         FIG.  25    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box B in  FIG.  15   . 
         FIG.  26    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box B in  FIG.  16   . 
         FIG.  27    is a partially enlarged view illustrating a schematic configuration of a portion indicated by a box B in  FIG.  17   . 
         FIG.  28    is a schematic cross-sectional view illustrating a portion of a process for forming a green light-emitting layer according to Comparative Example. 
         FIG.  29    is a schematic cross-sectional view illustrating a portion of the process for forming the green light-emitting layer according to Comparative Example. 
         FIG.  30    is a schematic cross-sectional view illustrating a portion of a process for forming a blue light-emitting layer according to Comparative Example. 
         FIG.  31    is a schematic cross-sectional view illustrating a portion of the process for forming the blue light-emitting layer according to Comparative Example. 
         FIG.  32    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer in a display device according to a modified example of the first embodiment of the disclosure. 
         FIG.  33    is a schematic cross-sectional view illustrating a portion of an example of a process for forming the light-emitting element layer illustrated in  FIG.  32   . 
         FIG.  34    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a second embodiment of the disclosure. 
         FIG.  35    is a schematic cross-sectional view illustrating a portion of an example of a process for forming the light-emitting element layer illustrated in  FIG.  34   . 
         FIG.  36    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  34   . 
         FIG.  37    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a third embodiment of the disclosure. 
         FIG.  38    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a fourth embodiment of the disclosure. 
         FIG.  39    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a fifth embodiment of the disclosure. 
         FIG.  40    is a flowchart illustrating an example of a process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  41    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  42    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  43    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  44    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  45    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  46    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  47    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  39   . 
         FIG.  48    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a sixth embodiment of the disclosure. 
         FIG.  49    is a flowchart illustrating an example of a process for forming a light-emitting element layer illustrated in  FIG.  48   . 
         FIG.  50    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  48   . 
         FIG.  51    is a schematic cross-sectional view illustrating a portion of an example of the process for forming the light-emitting element layer illustrated in  FIG.  48   . 
         FIG.  52    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a seventh embodiment of the disclosure. 
         FIG.  53    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to an eighth embodiment of the disclosure. 
         FIG.  54    is a flowchart illustrating an example of a process for forming a light-emitting element layer illustrated in  FIG.  53   . 
         FIG.  55    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a ninth embodiment of the disclosure. 
         FIG.  56    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a tenth embodiment of the disclosure. 
         FIG.  57    is a plan view illustrating an example of an arrangement pattern of green pixel electrodes, blue pixel electrodes, and red pixel electrodes. 
         FIG.  58    is a plan view illustrating an example of a forming pattern of a green light-emitting layer illustrated in  FIG.  56    in a case where pixel electrodes are in the arrangement pattern illustrated in  FIG.  57   . 
         FIG.  59    is a plan view illustrating an example of a forming pattern of a blue light-emitting layer illustrated in  FIG.  56    in a case where pixel electrodes are in the arrangement pattern illustrated in  FIG.  57   . 
         FIG.  60    is a plan view illustrating an example of a forming pattern of a red light-emitting layer illustrated in  FIG.  56    in a case where pixel electrodes are in the arrangement pattern illustrated in  FIG.  57   . 
         FIG.  61    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to an eleventh embodiment of the disclosure. 
         FIG.  62    is a cross-sectional view illustrating a schematic configuration of an active layer in a display device according to a twelfth embodiment of the disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Method for Manufacturing Display Device and Configuration 
     In the following description, the “same layer” means that it is formed through the same process (film formation step), the “lower layer” means that it is formed through a process before that of the compared layer, and the “upper layer” means that it is formed through a process after that of the compared layer. 
       FIG.  1    is a flowchart illustrating an example of a method for manufacturing a display device.  FIG.  2    is a schematic cross-sectional view illustrating an example of a configuration of a display region of a display device  2 . 
     In a case where a flexible display device is manufactured, as illustrated in  FIG.  1    and  FIG.  2   , first, a resin layer  12  is formed on a light-transmissive support substrate (a mother glass, for example) (step S 1 ). Next, a barrier layer  3  is formed (step S 2 ). Next, a thin film transistor layer (TFT layer)  4  is formed (step S 3 ). Next, a top-emitting type light-emitting element layer  5  is formed (step S 4 ). Next, a sealing layer  6  is formed (step S 5 ). Next, an upper face film is bonded on the sealing layer  6  (step S 6 ). 
     Next, the support substrate is peeled from the resin layer  12  due to irradiation with a laser light or the like (step S 7 ). Next, a lower face film  10  is bonded to the lower face of the resin layer  12  (step S 8 ). Next, a layered body including the lower face film  10 , the resin layer  12 , the barrier layer  3 , the thin film transistor layer  4 , the light-emitting element layer  5 , and the sealing layer  6  is divided to obtain a plurality of individual pieces (step S 9 ). Next, a function film  39  is bonded to the obtained individual pieces (step S 10 ). Next, an electronic circuit board (for example, an IC chip or an FPC) is mounted on a portion (terminal portion) of the display region located further outward (a non-display region or a frame region) than a portion where a plurality of subpixels are formed (step S 11 ). Note that steps S 1  to S 11  are executed by a display device manufacturing apparatus (including a film formation apparatus that executes the process from steps S 1  to S 5 ). 
     Examples of the material of the resin layer  12  include polyimide and the like. A portion of the resin layer  12  can be replaced by two resin films (for example, polyimide films) with an inorganic insulating film sandwiched therebetween. 
     The barrier layer  3  is a layer that inhibits foreign matter such as water and oxygen from entering the thin film transistor layer  4  and the light-emitting element layer  5 . For example, the barrier layer can be constituted of a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, or a layered film thereof formed by chemical vapor deposition (CVD). 
     The thin film transistor layer  4  includes a semiconductor film  15 , an inorganic insulating film  16  (gate insulating film) which is an upper layer above the semiconductor film  15 , a gate electrode GE and a gate wiring line GH 1  which are upper layers above the inorganic insulating film  16 , an inorganic insulating film  18  (interlayer insulating film) which is an upper layer above the gate electrode GE and the gate wiring line GH, a capacitance electrode CE which is an upper layer above the inorganic insulating film  18 , an inorganic insulating film  20  (interlayer insulating film) which is an upper layer above the capacitance electrode CE, a source wiring line SH which is an upper layer above the inorganic insulating film  20 , and a flattening film  21  (interlayer insulating film) which is an upper layer above the source wiring line SH. 
     The semiconductor film  15  is formed of low-temperature polysilicon (LTPS) or an oxide semiconductor (for example, an In—Ga—Zn—O based semiconductor), for example.  FIG.  2    illustrates the transistor that has a top gate structure, but the transistor may have a bottom gate structure. 
     The gate electrode GE, the gate wiring line GH, the capacitance electrode CE, and the source wiring line SH are each composed of a single layer film or a layered film of a metal, for example. including at least one of aluminum, tungsten, molybdenum, tantalum, chromium, titanium, and copper. 
     The inorganic insulating films  16 ,  18 , and  20  may be composed of, for example, a silicon oxide (SiOx) film, a silicon nitride (SiNx) film, or a silicon oxynitride (SiNO), or of a layered film of these, formed by a CVD method. The flattening film  21  may be composed of coatable organic materials such as polyimide and acrylic. 
     The light-emitting element layer  5  includes a cathode  25  (cathode electrode, so-called pixel electrode) which is an upper layer above the flattening film  21 , an edge cover  23  having insulating properties and covering an edge of the cathode  25 , an active layer  24  which is an upper layer above the edge cover  23 , the active layer  24  being an electroluminescent (EL) layer, and an anode  22  (anode electrode, so-called common electrode) which is an upper layer above the active layer  24 . The edge cover  23  is formed by applying an organic material such as a polyimide or an acrylic and then patterning the organic material by photolithography, for example. 
     For each subpixel, a light-emitting element ES (electroluminescent element) including the cathode  25  having an island shape, the active layer  24 , and the anode  25  and being a QLED is formed in the light-emitting element layer  5 , and a subpixel circuit for controlling the light-emitting element ES is formed in the thin film transistor layer  4 . 
     For example, the active layer  24  is formed by layering an electron injection layer, an electron transport layer, a light-emitting layer, a hole transport layer, and a hole injection layer in this order, from the lower layer side. It is also possible to adopt a configuration in which one or more of the electron injection layer, electron transport layer, hole transport layer, and hole injection layer are not formed. 
     The cathode  25  is a reflective electrode which is formed by layering, for example, indium tin oxide (ITO) and silver (Ag) or an alloy containing Ag, or formed from a material including Ag or Al and has light reflectivity. The anode  22  is a transparent electrode which is constituted of a thin film of Ag, Au, Pt, Ni, or Ir, a thin film of a MgAg alloy, or a light-transmissive conductive material such as ITO, or indium zinc oxide (IZO). When the display device is not a top-emitting type display device but is a bottom-emitting type display device, the lower face film  10  and the resin layer  12  are light-transmissive, the cathode  25  is a transparent electrode, and the anode  22  is a reflective electrode. 
     Alternatively, it is also possible to adopt a configuration in which the anode  22  having an island shape is formed as a so-called pixel electrode in an upper layer above the flattening film  21 , and the cathode  25  is formed as a so-called common electrode in an upper layer above the active layer  24 . In this case, for example, the active layer  24  is formed by layering a hole injection layer, a hole transport layer, a light-emitting layer, an electron transport layer, and an electron injection layer in this order, from the lower layer side. It is also possible to adopt a configuration in which one or more of the hole injection layer, hole transport layer, electron transport layer, and electron injection layer are not formed. In addition, when the display device is a top-emitting type display device, the cathode  25  is a transparent electrode and the anode  22  is a reflective electrode, while when the display device is a bottom-emitting type display device, the anode  22  is a transparent electrode and the cathode  25  is a reflective electrode. 
     In the light-emitting element ES, positive holes and electrons recombine inside the light-emitting layer in response to a drive current between the anode  22  and the cathode  25 , and when excitons generated due to this recombination transition from the lowest unoccupied molecular orbital (LUMO) or the conduction band to the highest occupied molecular orbital (HOMO) or the valence band of the quantum dots, light is emitted. 
     The sealing layer  6  is light-transmissive, and includes an inorganic sealing film  26  for covering the anode  25 , an organic buffer film  27  which is an upper layer above the inorganic sealing film  26 , and an inorganic sealing film  28  which is an upper layer above the organic buffer film  27 . The sealing layer  6  covering the light-emitting element layer  5  inhibits foreign matters such as water and oxygen from penetrating the light-emitting element layer  5 . 
     Each of the inorganic sealing film  26  and the inorganic sealing film  28  is an inorganic insulating film and can be formed of, for example, a silicon oxide film, a silicon nitride film, or a silicon oxynitride film, or a layered film of these, formed by CVD. The organic buffer film  27  is a transparent organic film having a flattening effect and can be formed of a coatable organic material such as an acrylic. The organic buffer film  27  can be formed, for example, by ink-jet application, and a bank for stopping droplets may be provided in a non-display region. 
     The lower face film  10  is, for example, a PET film bonded in a lower face of the resin layer  12  after the support substrate is peeled, to realize a display device having excellent flexibility. The function film  39  has at least one of an optical compensation function, a touch sensor function, and a protection function, for example. 
     The flexible display device has been described above, but when manufacturing the display device as a non-flexible display device, because typical formation of the resin layer and replacement of the substrate are not required, the process proceeds to step S 9  after the layering process on the glass substrate of steps S 2  to S 5  is executed. Furthermore, when a non-flexible display device is manufactured, a light-transmissive sealing member may be caused to adhere using a sealing adhesive instead of or in addition to forming the sealing layer  6 , under a nitrogen atmosphere. The light-transmissive sealing member can be formed from glass, plastic, or the like, and preferably has a concave shape. 
     One embodiment of the disclosure particularly relates to step S 4  of the method for manufacturing a display device described above. 
     First Embodiment 
     Hereinafter, an embodiment of the disclosure will be described in detail with reference to the drawings. However, shapes, dimensions, relative arrangements, and the like illustrated in the drawings are merely exemplary, and the scope of the disclosure should not be construed as limiting due to these. 
     As illustrated in  FIG.  2   , a display device  2  according to a first embodiment of the disclosure includes a lower face film  10 , a resin layer  12 , a barrier layer  3 , and a thin film transistor layer  4 , and a light-emitting element layer  5  is further formed on the substrate. Hereinafter, for convenience, a structure composed of the lower face film  10  (or support substrate), the resin layer  12 , the barrier layer  3 , and the thin film transistor layer  4  will be sometimes referred to as a “substrate”. 
     Configuration of Light-Emitting Element Layer 
       FIG.  3    is a cross-sectional view illustrating a schematic configuration of the light-emitting element layer  5  in the display device  2  according to the first embodiment of the disclosure. 
     As illustrated in  FIG.  3   , the display device  2  according to the first embodiment of the disclosure includes a green subpixel Pg (first subpixel) including a green pixel electrode PEg (first pixel electrode) provided on the substrate, a blue subpixel Pb (second subpixel) including a blue pixel electrode PEb (second pixel electrode) provided on the substrate, and a red subpixel Pr (third subpixel) including a red pixel electrode PEr (third pixel electrode) provided on the substrate. 
     The light-emitting element layer  5  according to the first embodiment of the disclosure includes a cathode  25  in an upper layer above the thin film transistor layer  4  as the green pixel electrode PEg, the blue pixel electrode PEb, and the red pixel electrode PEr. The light-emitting element layer  5  includes an edge cover  23  (bank) having insulating properties and covering an edge of the cathode  25 , and an active layer  24  in an upper layer above the edge cover  23 , the active layer  24  being an electroluminescent (EL) layer. The light-emitting element layer  5  includes an anode  22  in an upper layer above the active layer  24  as a common electrode. 
     The active layer  24  includes an electron injection layer  31  formed in a solid shape (common layer). The electron injection layer  31  is formed in a solid shape so as to cover the anode  22  and the edge cover  23 . This is not a limitation, and the electron injection layer  31  need not be formed, or may be formed in an island shape so as to individually cover the anode  22 . 
     The active layer  24  includes a green electron transport layer  33   g  (first charge transport layer) formed in an island shape and a green light-emitting layer  35   g  (first light-emitting layer) formed in an island shape, in the green subpixel Pg. 
     The green light-emitting layer  35   g  includes green quantum dots  42   g  (first quantum dots) that emit green light (see  FIGS.  19  to  31   ) and a cured green photosensitive resin  43   g  (see  FIGS.  19  to  31   ), and the green quantum dots  42   g  are fixed by the green photosensitive resin  43   g . The green light-emitting layer  35   g  is in direct contact with the green electron transport layer  33   g  and covers the entire upper surface of the green electron transport layer  33   g.    
     The green electron transport layer  33   g  is provided between the green pixel electrode PEg and the green light-emitting layer  35   g . The green electron transport layer  33   g  is composed of an electron transport material capable of being etched using an etching solution  56  that does not erode the green light-emitting layer  35   g  (i.e., cured green photosensitive resin  43   g ). The photosensitive resin after curing is often insoluble in an alkaline solution such as a potassium hydroxide (KOH) aqueous solution, a tetramethylammonium hydroxide (TMAH) aqueous solution, a sodium carbonate (Na 2 CO 3 ) aqueous solution, and a sodium hydrogen carbonate (NaHCO 3 ) aqueous solution. Thus, the etching solution  56  is preferably an alkaline solution in which the green photosensitive resin  43   g  is insoluble. In this case, the green electron transport layer  33   g  is composed of an electron transport material soluble in the alkaline solution in which the green photosensitive resin  43   g  is insoluble. Such an electron transport material is an oxide having, as a main composition, an amphoteric metal such as ZnO, AlZnO, LiZnO, or MgZnO, for example. 
     The active layer  24  includes a blue electron transport layer  33   b  (second charge transport layer) formed in an island shape, and a blue light-emitting layer  35   b  (second light-emitting layer) formed in an island shape, in the blue subpixel Pb. 
     The blue light-emitting layer  35   b  includes blue quantum dots  42   b  (second quantum dots) that emit blue light (see  FIGS.  22  to  24   , and  FIGS.  30  to  31   ), and a cured blue photosensitive resin  43   b  (see  FIGS.  22  to  24   , and  FIGS.  30  to  31   ), and the blue quantum dots  42   b  are fixed by the cured blue photosensitive resin  43   b . The blue light-emitting layer  35   b  is in direct contact with the blue electron transport layer  33   b  and covers the entire upper surface of the blue electron transport layer  33   b.    
     The blue electron transport layer  33   b  is provided between the blue pixel electrode PEb and the blue light-emitting layer  35   b . The blue electron transport layer  33   b  is composed of an electron transport material capable of being etched using the etching solution  56  that does not erode the blue light-emitting layer  35   b  (i.e., the cured blue photosensitive resin  43   b ). The photosensitive resin after curing is often insoluble in the alkaline solution as described above. Thus, the etching solution  56  is preferably an alkaline solution in which the blue photosensitive resin  43   b  is insoluble. In this case, the blue electron transport layer  33   b  is preferably composed of an electron transport material soluble in the alkaline solution in which the blue photosensitive resin  43   b  is insoluble. Such an electron transport material is an oxide having, as a main composition, an amphoteric metal such as ZnO, AlZnO, LiZnO, or MgZnO, for example. 
     The active layer  24  includes a red electron transport layer  33   r  (third charge transport layer) formed in an island shape, and a red light-emitting layer  35   r  (third light-emitting layer) formed in an island shape, in the red subpixel Pr. 
     The red light-emitting layer  35   r  includes red quantum dots  42   r  (third quantum dots)(see  FIGS.  25  to  28   ) that emits red light and a cured red photosensitive resin  43   r  (see  FIGS.  25  to  28   ), and the red quantum dots  42   r  are fixed by the red photosensitive resin  43   r . The red light-emitting layer  35   r  is in direct contact with the red electron transport layer  33   r , and covers the entire upper surface of the red electron transport layer  33   r.    
     The red electron transport layer  33   r  is provided between the red pixel electrode PEr and the red light-emitting layer  35   r . The red electron transport layer  33   r  is composed of an electron transport material capable of being etched using the etching solution  56  that does not erode the red light-emitting layer  35   r  (i.e., the cured red photosensitive resin  43   r ). The photosensitive resin after curing is often insoluble in the alkaline solution as described above. Thus, the etching solution  56  is preferably an alkaline solution in which the red photosensitive resin  43   r  is insoluble. In this case, the red electron transport layer  33   r  is composed of an electron transport material soluble in the alkaline solution in which the red photosensitive resin  43   r  is insoluble. Such an electron transport material is an oxide having, as a main composition, an amphoteric metal such as ZnO, AlZnO, LiZnO, or MgZnO, for example. 
     The green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  have the same polarity as each other, and are separated from each other. The green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  may be formed of materials different from each other or the same material as each other, and may have different film thicknesses from each other or the same film thickness as each other. For example, preferably, in view of a resonance effect, the material and/or film thickness of the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  are selected. 
     The active layer  24  includes a hole transport layer  37  (fourth charge transport layer) formed in a solid shape. The hole transport layer  37  has a reverse polarity with respect to the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r . The hole transport layer  37 , along with the anode  22 , is located on the opposite side of the electron injection layer  31  with respect to each of the green light-emitting layer  35   g , the blue light-emitting layer  35   b , and the red light-emitting layer  35   r . The hole transport layer  37  is formed in a solid shape so as to cover the green light-emitting layer  35   g , the red light-emitting layer  35   r , and the blue light-emitting layer  35   b  (and when exposed, the exposed portion of the electron injection layer  31  and the exposed portion of the edge cover  23 ). This is not a limitation, and the hole transport layer  37  need not be formed, or may be paired with the cathode  25  to be formed in an island shape separated for each pixel so as to individually cover the green light-emitting layer  35   g , the red light-emitting layer  35   r , and the blue light-emitting layer  35   b . Further, the hole transport layer  37  may have a multilayer structure. 
     Although not illustrated in the drawings, the active layer  24  may include one or more additional electron transport layers between the electron injection layer  31  and the green electron transport layer  33   g , may include one or more additional electron transport layers between the electron injection layer  31  and the red electron transport layer  33   r , or may include one or more additional electron transport layers between the electron injection layer  31  and the blue electron transport layer  33   b . The additional electron transport layer may be formed in an island shape separately for each of the green subpixel Pg, the red subpixel Pr, and the blue subpixel Pb, or may be formed commonly in a solid shape. 
     Light-Emitting Element Layer Forming Process 
     Hereinafter, with reference to  FIGS.  4  to  27   , a process for forming the light-emitting element layer  5  in a method for manufacturing the display device  2  according to the first embodiment of the disclosure (i.e., step S 4  in  FIG.  1   ) will be described.  FIG.  4    is a flowchart illustrating an example of the process for forming the light-emitting element layer  5  illustrated in  FIG.  3   .  FIGS.  5  to  18    are schematic cross-sectional views illustrating portions of the example of the process for forming the light-emitting element layer  5  illustrated in  FIG.  3   .  FIGS.  19  to  24    are partially enlarged views illustrating schematic configurations of portions indicated by boxes A in  FIGS.  7  to  9    and  FIGS.  11  to  13   , respectively.  FIGS.  25  to  27    are partially enlarged views illustrating schematic configurations of the portions indicated by boxes B in  FIGS.  15  to  17   , respectively. 
     First, as illustrated in  FIG.  5   , the resin layer  12 , the barrier layer  3 , and the thin film transistor layer  4  are formed in this order on the support substrate  50 . 
     Then, as illustrated in  FIG.  4    and  FIG.  5   , the cathodes  25  are formed on the thin film transistor layer  4  as the green pixel electrode PEg, the red pixel electrode PEr, and the blue pixel electrode PEb (step S 21 ). Subsequently, the edge cover  23  is formed so as to cover a perimeter edge portion of each of the cathodes  25  (step S 22 ). Subsequently, the electron injection layer  31  is formed so as to cover the cathodes  25  (step S 23 ). 
     Then, formation of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (step S 24 ), formation of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (step S 30 ), and formation of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (step S 36 ) are sequentially performed. Steps S 24 , S 30 , and S 36  may be performed in any order. In the present specification, a case in which steps S 24 , S 30 , and S 36  are performed in this order will be described as an example. 
     In step S 24 , first, as illustrated in  FIG.  4    and  FIG.  6   , the green electron transport layer  33   g  is formed (first charge transport layer forming step) (step S 25 ), and a green coating liquid  34   g  is applied on the green electron transport layer  33   g  (first mixture application step) (step S 26 ). In step S 25 , the green electron transport layer  33   g  is formed in a solid shape over the green pixel electrode PEg and over the red pixel electrode PEr and the blue pixel electrode PEb. In step S 26 , the green coating liquid  34   g  is applied directly onto the entire green electron transport layer  33   g  in a solid shape. The green coating liquid  34   g  is a first mixture in which the green quantum dots  42   g  are mixed in an uncured green photosensitive resin  41   g  (see  FIG.  19   ). 
     Subsequently, in step S 24 , as illustrated in  FIG.  4    and  FIG.  7   , the green coating liquid  34   g  is pattern-exposed using a green photomask  52   g  so as to form a pattern shape in which a portion of the green coating liquid  34   g  to be the green light-emitting layer  35   g  is cured, and the other portion is not cured (first mixture exposure step) (step S 27 ). At this time, as illustrated in  FIG.  19   , the green quantum dots  42   g  of the cured portion (i.e., the green light-emitting layer  35   g ) are fixed by the cured green photosensitive resin  43   g . At the same time, some of the green quantum dots  42   g  are adsorbed and/or mixed into the green electron transport layer  33   g.    
     Subsequently, in step S 24 , as illustrated in  FIG.  4    and  FIG.  8   , the uncured portion of the green coating liquid  34   g  is removed by a developer  54  to develop the green light-emitting layer  35   g  (that is, the cured portion of the green coating liquid  34   g ) (first mixture removal step) (step S 28 ). The developer  54  is an alkaline solution. In this way, the green light-emitting layer  35   g  is formed using a photolithography technique. At this time, as illustrated in  FIG.  20   , the green quantum dots  42   g  of the uncured portion are removed along with the uncured green photosensitive resin  41   g . However, among the green quantum dots  42   g  of the uncured portion, a part of the green quantum dots  42   g  adsorbed or mixed into the green electron transport layer  33   g  remains in the surface and/or interior of the green electron transport layer  33   g  corresponding to the uncured portion without being removed. 
     Finally, at step S 24 , as illustrated in  FIG.  4    and  FIG.  9   , the green light-emitting layer  35   g  is used as a mask to etch the green electron transport layer  33   g  using the etching solution  56  (first etching step) (step S 29 ). This removes the green electron transport layer  33   g  corresponding to the uncured portion of the green coating liquid  34   g . At this time, as illustrated in  FIG.  21   , the green quantum dots  42   g  remaining in the green electron transport layer  33   g  corresponding to the uncured portion are removed along with the green electron transport layer  33   g  corresponding to the uncured portion. The etching solution  56  in step S 29  is preferably the same alkaline solution as the developer  54  in step S 28 . When it is the same, steps S 28  and S 29  can be performed sequentially in a single step or in parallel, and thus the number of steps of the method for manufacturing the display device  2  can be further reduced. In other words, preferably, the uncured green photosensitive resin  41   g  is soluble in the etching solution  56 , and the cured green photosensitive resin  43   g  is insoluble in the etching solution  56 . 
     Note that in step S 29 , the green electron transport layer  33   g  corresponding to the green light-emitting layer  35   g  may be side-etched. Thus, in a plan view, the green light-emitting layer  35   g  is preferably formed wider than an effective light-emitting region of the green subpixel Pg, that is, an opening Ag of the edge cover  23 . Furthermore, the green light-emitting layer  35   g  is as wide as or wider than the green electron transport layer  33   g  after etching in a plan view. 
     In subsequent step S 30 , first, as illustrated in  FIG.  4    and  FIG.  10   , the blue electron transport layer  33   b  is formed (second charge transport layer forming step) (step S 31 ), and a blue coating liquid  34   b  is applied on the blue electron transport layer  33   b  (second mixture application step) (step S 32 ). In step S 31 , the blue electron transport layer  33   b  is formed in a solid shape over the blue pixel electrode PEb and over the red pixel electrode PEr and the green pixel electrode PEg. Furthermore, in step S 32 , the blue coating liquid  34   b  is applied directly on the entire blue electron transport layer  33   b  into a solid shape. The blue coating liquid  34   b  is a second mixture in which the blue quantum dots  42   b  are mixed into an uncured blue photosensitive resin  41   b  (see  FIG.  22    and  FIG.  30   ). The blue photosensitive resin  41   b  may be the same resin as the green photosensitive resin  41   g  or may be a different resin. 
     Subsequently, in step S 30 , as illustrated in  FIG.  4    and  FIG.  11   , the blue coating liquid  34   b  is pattern-exposed using a blue photomask  52   b  so as to form a pattern shape in which a portion to be the blue light-emitting layer  35   b  is cured, and the other portion is not cured (second mixture exposure step) (step S 33 ). At this time, as illustrated in  FIG.  22   , the blue quantum dots  42   b  of the cured portion (i.e., the blue light-emitting layer  35   b ) are fixed by the cured blue photosensitive resin  43   b . At the same time, some of the blue quantum dots  42   b  are adsorbed and/or mixed in the blue electron transport layer  33   b . On the other hand, the green light-emitting layer  35   g  is covered by the blue electron transport layer  33   b , and thus the blue quantum dots  42   b  are not adsorbed or mixed in the green light-emitting layer  35   g.    
     Subsequently, in step S 30 , as illustrated in  FIG.  4    and  FIG.  12   , the uncured portion of the blue coating liquid  34   b  is removed by the developer  54  to develop the blue light-emitting layer  35   b  (i.e., the cured portion of the blue coating liquid  34   b ) (second mixture removal step) (step S 34 ). The developer  54  is an alkaline solution. In this way, the blue light-emitting layer  35   b  is formed using a photolithography technique. At this time, as illustrated in  FIG.  23   , the blue quantum dots  42   b  of the uncured portion are removed along with the uncured blue photosensitive resin  41   b . However, among the blue quantum dots  42   b  of the uncured portion, a part of the blue quantum dots  42   b  adsorbed or mixed in the blue electron transport layer  33   b  remains in the surface and/or interior of the blue electron transport layer  33   b  without being removed. In addition, as illustrated in  FIG.  12    and  FIG.  23   , the green light-emitting layer  35   g  remains covered with the blue electron transport layer  33   b.    
     Finally, in step S 30 , as illustrated in  FIG.  4    and  FIG.  13   , the blue light-emitting layer  35   b  is used as a mask to etch the blue electron transport layer  33   b  using the etching solution  56  (second etching step) (step S 35 ). This removes the blue electron transport layer  33   b  corresponding to the uncured portion of the blue coating liquid  34   b . At this time, as illustrated in  FIG.  24   , the blue quantum dots  42   b  remaining in the blue electron transport layer  33   b  corresponding to the uncured portion are removed along with the blue electron transport layer  33   b . After removal, the green light-emitting layer  35   g  is at least partially exposed. The etching solution  56  in step S 35  is preferably the same alkaline solution as the developer  54  in step S 34 . When it is the same, steps S 34  and S 35  can be performed sequentially in a single step or in parallel, and thus the number of steps of the method for manufacturing the display device  2  can be further reduced. In other words, preferably, the uncured blue photosensitive resin  41   b  is soluble in the etching solution  56 , and the cured blue photosensitive resin  43   b  is insoluble in the etching solution  56 . 
     Note that in step S 35 , the blue electron transport layer  33   b  corresponding to the blue light-emitting layer  35   b  may be side-etched. Thus, in a plan view, the blue light-emitting layer  35   b  is preferably formed wider than an effective light-emitting region of the blue subpixel Pb, that is, an opening Ab of the edge cover  23 . In addition, the blue light-emitting layer  35   b  is as wide as or wider than the blue electron transport layer  33   b  after etching in a plan view. 
     In subsequent step S 36 , first, as illustrated in  FIG.  4    and  FIG.  14   , the red electron transport layer  33   r  is formed (step S 37 ), and a red coating liquid  34   r  is applied on the red electron transport layer  33   r  (step S 38 ). In step S 37 , the red electron transport layer  33   r  is formed in a solid shape over the red pixel electrode PEr and over the green pixel electrode PEg and the blue pixel electrode PEb. In addition, in step S 38 , the red coating liquid  34   r  is applied directly on the entire red electron transport layer  33   r  into a solid shape. The red coating liquid  34   r  is a third mixture in which the red quantum dots  42   r  are mixed into an uncured red photosensitive resin  41   r  (see  FIG.  25   ). The red photosensitive resin  41   r  may be the same resin as the green photosensitive resin  41   g  or a different resin, and may be the same resin as the blue photosensitive resin  41   b  or a different resin. 
     Subsequently, in step S 36 , as illustrated in  FIG.  4    and  FIG.  15   , the red coating liquid  34   r  is pattern-exposed using a red photomask  52   r  so as to form a pattern shape in which a portion to be the red light-emitting layer  35   r  is cured, and the other portion is not cured (step S 39 ). At this time, as illustrated in  FIG.  25   , the red quantum dots  42   r  of the cured portion (i.e., the red light-emitting layer  35   r ) are fixed by the cured red photosensitive resin  43   r . At the same time, a part of the red quantum dots  42   r  is adsorbed and/or mixed into the red electron transport layer  33   r . Further, as illustrated in  FIG.  15    and  FIG.  25   , the green light-emitting layer  35   g  is covered with the red electron transport layer  33   r , and thus the red quantum dots  42   r  are not adsorbed or mixed into the green light-emitting layer  35   g . Similarly, as illustrated in  FIG.  15   , the blue light-emitting layer  35   b  is covered with the red electron transport layer  33   r , and thus the red quantum dots  42   r  are not adsorbed or mixed into the blue light-emitting layer  35   b.    
     Subsequently, in step S 36 , as illustrated in  FIG.  4    and  FIG.  16   , the uncured portion of the red coating liquid  34   r  is removed by the developer  54  to develop the red light-emitting layer  35   r  (i.e., the cured portion of the red coating liquid  34   r ) (third mixture removal step) (step S 40 ). The developer  54  is an alkaline solution. In this way, the red light-emitting layer  35   r  is formed using a photolithography technique. At this time, as illustrated in  FIG.  26   , the red quantum dots  42   r  of the uncured portion are removed along with the uncured red photosensitive resin  41   r . However, among the red quantum dots  42   r  of the uncured portion, a part of the red quantum dots  42   r  adsorbed or mixed into the red electron transport layer  33   r  remains in the surface and/or interior of the red electron transport layer  33   r  without being removed. In addition, as illustrated in  FIG.  16    and  FIG.  26   , the green light-emitting layer  35   g  remains covered with the red electron transport layer  33   r . Similarly, as illustrated in  FIG.  16   , the blue light-emitting layer  35   b  remains covered with the red electron transport layer  33   r.    
     In step S 36 , finally, as illustrated in  FIG.  4    and  FIG.  17   , the red light-emitting layer  35   r  is used as a mask to etch the red electron transport layer  33   r  using the etching solution  56  (step S 41 ). This removes the red electron transport layer  33   r  corresponding to the uncured portion of the red coating liquid  34   r . At this time, as illustrated in  FIG.  27   , the red quantum dots  42   r  remaining in the red electron transport layer  33   r  corresponding to the uncured portion are removed along with the red electron transport layer  33   r . After removal, the green light-emitting layer  35   g  is at least partially exposed, and the blue light-emitting layer  35   b  is also at least partially exposed. The etching solution  56  in step S 41  is preferably the same alkaline solution as the developer  54  in step S 40 . When it is the same, steps S 40  and S 41  can be performed sequentially in a single step or in parallel, and thus the number of steps of the method for manufacturing the display device  2  can be further reduced. In other words, preferably, the uncured red photosensitive resin  41   r  is soluble in the etching solution  56 , and the cured red photosensitive resin  43   r  is insoluble in the etching solution. 
     Note that in step S 41 , the red electron transport layer  33   r  corresponding to the red light-emitting layer  35   r  may be side-etched. Thus, in a plan view, the red light-emitting layer  35   r  is preferably formed wider than an effective light-emitting region of the red subpixel Pr, that is, an opening Ar of the edge cover  23 . Furthermore, in a plan view, the red light-emitting layer  35   r  is as wide as or wider than the red electron transport layer  33   r  after etching. 
     Then, as illustrated in  FIG.  4    and  FIG.  18   , the hole transport layer  37  is formed on the green light-emitting layer  35   g , the blue light-emitting layer  35   b , and the red light-emitting layer  35   r  (step S 42 ), and the anode  22  is formed on the hole transport layer  37  (step S 43 ). 
     Comparative Example 
     Hereinafter, with reference to  FIGS.  28  to  31   , a process for forming a green light-emitting layer  135   g , a blue light-emitting layer  135   b , and a red light-emitting layer  135   r  in a method for manufacturing a display device according to Comparative Example will be described.  FIGS.  28  to  29    are schematic cross-sectional views illustrating portions of the process for forming the green light-emitting layer  135   g  according to Comparative Example.  FIGS.  30  to  31    are schematic cross-sectional views illustrating portions of the process for forming the blue light-emitting layer  135   b  according to Comparative Example. 
     As illustrated in  FIG.  28   , in Comparative Example, an electron transport layer  133  is formed in a solid shape over the green subpixel Pg and the blue subpixel Pb (and, although not illustrated, the red subpixel Pr). Then, the green coating liquid  34   g  is applied directly, in a solid shape, on the entire electron transport layer  133 . The green coating liquid  34   g  is then cured in a pattern shape. As illustrated in  FIG.  29   , the uncured portion of the green coating liquid  34   g  is then removed using the developer  54 , thereby developing the green light-emitting layer  135   g.    
     Subsequently, as illustrated in  FIG.  30   , the blue coating liquid  34   b  is formed in a solid shape over the green subpixel Pg and the blue subpixel Pb (and, although not illustrated, the red subpixel Pr). At this time, the blue coating liquid  34   b  is applied directly on the green light-emitting layer  135   g  and the electron transport layer  133 . Then, the blue coating liquid  34   b  is cured in a pattern shape. As illustrated in  FIG.  31   , the uncured portion of the blue coating liquid  34   b  is then removed using the developer  54 , thereby developing the blue light-emitting layer  135   b.    
     Subsequently, although not illustrated, the red coating liquid  34   r  is formed in a solid shape over the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. At this time, the red coating liquid  34   r  is applied directly on the green light-emitting layer  135   g , the blue light-emitting layer  135   b , and the electron transport layer  133 . The red coating liquid  34   r  is then cured in a pattern shape. Although not illustrated, the uncured portion of the red coating liquid  34   r  is then removed using the developer  54 , thereby developing the red light-emitting layer. 
     There are various problems in the light-emitting layer forming process according to such Comparative Example. 
     First, there is a problem in that the green quantum dots  42   g  remain in the electron transport layer  133  in the red subpixel Pr and the blue subpixel Pb as a residue. 
     As illustrated in  FIG.  28   , the green coating liquid  34   g  is applied directly onto the electron transport layer  133 . Thus, a part of the green quantum dots  42   g  in the green coating liquid  34   g  is adsorbed and/or mixed in the electron transport layer  133 . As illustrated in  FIG.  29   , when the uncured portion is removed, the green quantum dots  42   g  dispersed in the uncured green photosensitive resin  41   g  are removed along with the green photosensitive resin  41   g . On the other hand, the green quantum dots  42   g  adsorbed and/or mixed in the electron transport layer  133  remain in the surface and/or interior of the electron transport layer  133  without being removed. 
     Similarly, there is a problem in that the blue quantum dots  42   b  remain in the electron transport layer  133  in the red subpixel Pr as a residue. 
     Secondly, there is a problem in that performance of the electron transport layer  133  in the blue subpixel Pb and the red subpixel Pr is lower than performance of the electron transport layer  133  in the green subpixel Pg. 
     As illustrated in  FIG.  29   , a portion of the electron transport layer  133  corresponding to the green light-emitting layer  135   g  is not exposed to the developer  54 . On the other hand, the other portion of the electron transport layer  133  is exposed to the developer  54  for developing the green light-emitting layer  135   g . The electron transport layer  133  exposed to the developer  54  has worse performance than the unexposed electron transport layer  133 . 
     Similarly, there is a problem in that performance of the electron transport layer  133  in the red subpixel Pr is lower than performance of the electron transport layer  133  in the blue subpixel Pb. 
     In addition, there is a problem in that the blue quantum dots  42   b  remain in the green light-emitting layer  135   g  in the green subpixel Pg as a residue. 
     As illustrated in  FIG.  30   , the blue coating liquid  34   b  is applied directly onto the green light-emitting layer  135   g . Thus, a part of the blue quantum dots  42   b  in the blue coating liquid  34   b  is adsorbed and/or mixed into the green light-emitting layer  135   g . As illustrated in  FIG.  31   , when the uncured portion is removed, the blue quantum dots  42   b  dispersed in the uncured blue photosensitive resin  41   b  are removed along with the blue photosensitive resin  41   b . On the other hand, the blue quantum dots  42   b  adsorbed and/or mixed in the green light-emitting layer  135   g  remain in the surface and/or interior of the green light-emitting layer  135   g  without being removed. 
     Similarly, there is a problem in that the red quantum dots  42   r  remain in the green light-emitting layer  135   g  in the green subpixel Pg and the blue light-emitting layer  135   b  in the blue subpixel Pb as a residue. 
     Advantageous Effects 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the green light-emitting layer  35   g  is used as a mask to etch the green electron transport layer  33   g  ( FIG.  9   , step S 29 ). Similarly, the blue light-emitting layer  35   b  is used as a mask to etch the blue electron transport layer  33   b  ( FIG.  13   , step S 35 ), and the red light-emitting layer  35   r  is used as a mask to etch the red electron transport layer  33   r  ( FIG.  17   , step S 41 ). Thus, the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  can be etched in a highly accurate pattern. This can improve the resolution and/or yield of the display device  2 . 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the upper surface of the portion of the green electron transport layer  33   g  corresponding to the green light-emitting layer  35   g  is covered with the green light-emitting layer  35   g  and not exposed to the developer  54  and the etching solution  56 . Similarly, the upper surface of the portion of the blue electron transport layer  33   b  corresponding to the blue light-emitting layer  35   b  is covered with the blue light-emitting layer  35   b  and not exposed to the developer  54  and the etching solution  56 , and the upper surface of the portion of the red electron transport layer  33   r  corresponding to the red light-emitting layer  35   r  is covered with the red light-emitting layer  35   r  and not exposed to the developer  54  and the etching solution  56 . Thus, the performance of the portion of the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  remaining in the finished product does not deteriorate, which leads to high reliability. Accordingly, it is possible to improve the reliability of the display device  2 . 
     As described above, the method for manufacturing the display device  2  according to the first embodiment does not include a process of forming and removing a patterned photosensitive resin not included in the finished product. This can reduce the number of steps of the method for manufacturing the display device  2 . 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the blue quantum dots  42   b  remaining in the blue electron transport layer  33   b  corresponding to the uncured portion of the blue coating liquid  34   b  are removed along with the blue electron transport layer  33   b , and the red quantum dots  42   r  remaining in the red electron transport layer  33   r  corresponding to the uncured portion of the red coating liquid  34   r  are removed along with the red electron transport layer  33   r . Furthermore, the blue quantum dots  42   b  and the red quantum dots  42   r  are not adsorbed or mixed in the green light-emitting layer  35   g . Thus, the blue quantum dots  42   b  and the red quantum dots  42   r  that remain in the green subpixel Pg as a residue can be reduced, so that color purity of the green subpixel Pg can be improved. 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the green quantum dots  42   g  remaining in the green electron transport layer  33   g  corresponding to the uncured portion of the green coating liquid  34   g  are removed along with the green electron transport layer  33   g , and the red quantum dots  42   r  remaining in the red electron transport layer  33   r  corresponding to the uncured portion of the red coating liquid  34   r  are removed along with the red electron transport layer  33   r . Furthermore, the red quantum dots  42   r  are not adsorbed or mixed in the blue light-emitting layer  35   b . As a result, similarly, the green quantum dots  42   g  and the red quantum dots  42   r  that remain in the blue subpixel Pb as a residual can be reduced, so that color purity of the blue subpixel Pb can be improved. 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the green quantum dots  42   g  remaining in the green electron transport layer  33   g  corresponding to the uncured portion of the green coating liquid  34   g  are removed along with the green electron transport layer  33   g , and the blue quantum dots  42   b  remaining in the blue electron transport layer  33   b  corresponding to the uncured portion of the blue coating liquid  34   b  are removed along with the blue electron transport layer  33   b . Thus, the green quantum dots  42   g  and the blue quantum dots  42   b  that remain in the red subpixel Pr as a residue can be reduced, so that color purity of the red subpixel Pr can be improved. 
     Such improvement of the color purity can improve color gamut of the display device  2 . 
     As described above, according to the method for manufacturing the display device  2  according to the first embodiment, the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  are separated from each other. This can reduce a leakage current through the electron transport layers between the subpixels. Thus, it is possible to reduce power consumption of the display device  2 . 
     Modified Example 
     Hereinafter, a description will be given of a modified example of the first embodiment with reference to  FIGS.  32  to  33   . 
       FIG.  32    is a cross-sectional view illustrating a schematic configuration of the light-emitting element layer  5  in the display device  2  according to the modified example of the first embodiment.  FIG.  33    is a schematic cross-sectional view illustrating a portion of an example of a process for forming the light-emitting element layer  5  illustrated in  FIG.  32   . 
     The light-emitting element layer  5  of the display device  2  according to the modified example illustrated in  FIG.  32    is different from the light-emitting element layer  5  illustrated in  FIG.  3   , and includes the green electron transport layer  33   g  also in the red subpixel Pr and the blue subpixel Pb. The other configuration of the light-emitting element layer  5  illustrated in  FIG.  32    is similar to the light-emitting element layer  5  illustrated in  FIG.  3   . 
     The green electron transport layer  33   g  according to the present modified example is formed in a solid shape over the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. A first portion of the green electron transport layer  33   g  corresponding to the green light-emitting layer  35   g  is formed thick. A second portion of the green electron transport layer  33   g  corresponding to the blue light-emitting layer  35   b  and a third portion corresponding to the red light-emitting layer  35   r  are formed thinner than the first portion. 
     As illustrated in  FIG.  33   , such a green electron transport layer  33   g  can be manufactured by terminating the etching of the green electron transport layer  33   g  in step  29  at a time point when a lower portion of the green electron transport layer  33   g  remains. As a result, for a portion of the green electron transport layer  33   g  that does not correspond to the green light-emitting layer  35   g , an upper portion contaminated with the green quantum dots  42   g  is removed, and a clean lower portion remains. Thus, in the red subpixel Rr and the blue subpixel Pb, the electron injection layer  31  (or cathode  25 ) is not exposed to the etching solution  56 , so that performance deterioration of the electron injection layer  31  (or cathode  25 ) can be prevented. 
     Note that this modification is applicable to each of second to twelfth embodiments described below. 
     Second Embodiment 
       FIG.  34    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a second embodiment of the disclosure.  FIGS.  35  to  36    are schematic cross-sectional views, respectively, illustrating portions of an example of a process for forming a light-emitting element layer  5  illustrated in  FIG.  34   . 
     As illustrated in  FIG.  34   , the light-emitting element layer  5  according to the present embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except that a side surface of a green electron transport layer  33   g  is covered with a green light-emitting layer  35   g , a side surface of a blue electron transport layer  33   b  is covered with a blue light-emitting layer  35   b , and a side surface of a red electron transport layer  33   r  is covered with a red light-emitting layer  35   r.    
     According to the configuration according to the present embodiment, an upper surface and the side surface of the green electron transport layer  33   g  are covered with the green light-emitting layer  35   g . This coating prevents direct contact between the green electron transport layer  33   g  and a hole transport layer  37 , and thus a leakage current between a cathode  25  and an anode  22  which are a green pixel electrode PEg is reduced. Similarly, the coating of an upper surface and the side surface of the blue electron transport layer  33   b  by the blue light-emitting layer  35   b  reduces a leakage current between a cathode  25  and an anode  22  which are a blue pixel electrode PEb, and the coating of an upper surface and the side surface of the red electron transport layer  33   r  by the red light-emitting layer  35   r  reduces a leakage current between a cathode  25  and an anode  22  which are a red pixel electrode PEr. 
     Such a coating can be manufactured by further advancing etching in steps S 29 , S 35 , and S 41  to perform side etching. Specifically, in step S 29 , as illustrated in  FIG.  35   , side etching is performed so as to remove a perimeter edge portion of a portion of the green electron transport layer  33   g  corresponding to the green light-emitting layer  35   g . This eliminates a portion of the green electron transport layer  33   g  corresponding to the perimeter edge portion of the green light-emitting layer  35   g , and as a result, the perimeter edge portion of the green light-emitting layer  35   g  is in a state of being free in an etching solution  56 . As illustrated in  FIG.  36   , when the etching is ended, the etching solution  56  is eliminated, and thus the perimeter edge portion of the green light-emitting layer  35   g  is suspended to cover the side surface of the green electron transport layer  33   g . Similarly, in step S 35 , side etching is performed so as to remove a perimeter edge portion of a portion of the blue electron transport layer  33   b  corresponding to the blue light-emitting layer  35   b . Further, in step S 41 , side etching is performed so as to remove a perimeter edge portion of a portion of the red electron transport layer  33   r  corresponding to the red light-emitting layer  35   r.    
     Note that the green light-emitting layer  35   g  is formed wider than an opening Ag of an edge cover  23  in such a manner that the green electron transport layer  33   g  after side etching covers the entire effective light-emitting region of the green subpixel Pg. Similarly, the blue light-emitting layer  35   b  is formed wider than an opening Ab of the edge cover  23 , and the red light-emitting layer  35   r  is formed wider than an opening Ar of the edge cover  23 . 
     By such a coating, the side surface of the green electron transport layer  33   g  is not exposed to the etching solution  56  in step S 35 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and performance deterioration of the perimeter edge portion of the green electron transport layer  33   g . Similarly, the side surface of the green electron transport layer  33   g  and the side surface of the blue electron transport layer  33   b  are not exposed to the etching solution  56  in step S 41 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and the blue electron transport layer  33   b  and performance deterioration of the perimeter edge portions of the green electron transport layer  33   g  and the blue electron transport layer  33   b . Thus, the method for manufacturing the display device  2  according to the second embodiment can further improve reliability of the display device  2  as compared to the method for manufacturing the display device  2  according to the first embodiment described above. 
     Furthermore, this coating prevents direct contact between the green electron transport layer  33   g  and the hole transport layer  37 , and thus reduces a leakage current between the cathode  25  and the anode  22  which are the green pixel electrode PEg. Similarly, this coating reduces a leakage current between the cathode  25  and the anode  22  which are the blue pixel electrode PEb, and reduces a leakage current between the cathode  25  and the anode  22  which are the red pixel electrode PEr. Thus, as compared to the method for manufacturing the display device  2  according to the first embodiment, the method for manufacturing the display device  2  according to the second embodiment can further improve the luminous efficiency of the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. This can reduce power consumption of the display device  2 . 
     Similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the second embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, the number of steps of the method for manufacturing the display device  2  can be reduced. Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration between the configuration according to the first embodiment described above and the configuration according to the second embodiment is also included in the scope of the disclosure. For example, at least a part of the side surface of the green electron transport layer  33   g  may be covered with the green light-emitting layer  35   g , at least a part of the side surface of the blue electron transport layer  33   b  may be covered with the blue light-emitting layer  35   b , and/or at least a part of the side surface of the red electron transport layer  33   r  may be covered with the red light-emitting layer  35   r.    
     Third Embodiment 
       FIG.  37    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a third embodiment of the disclosure. As illustrated in  FIG.  37   , the light-emitting element layer  5  according to the third embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except the following three points. 
     One point is a point where a part of perimeter edge portions of a green electron transport layer  33   g  and a green light-emitting layer  35   g  (a left side portion in  FIG.  37   ) overlaps with a part of perimeter edge portions of a blue electron transport layer  33   b  and a blue light-emitting layer  35   b  (a right side portion of  FIG.  37   ). That is, the portion of the blue electron transport layer  33   b  overlaps with the portion of the green electron transport layer  33   g  with the green light-emitting layer  35   g  interposed therebetween. 
     Another point is a point where another part of the perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (the right side portion in  FIG.  37   ) overlaps with a part of perimeter edge portions of a red electron transport layer  33   r  and a red light-emitting layer  35   r  (the left side portion in  FIG.  37   ). That is, the portion of the red electron transport layer  33   r  overlaps with another portion of the green electron transport layer  33   g  with the green light-emitting layer  35   g  interposed therebetween. 
     Still another point is a point where another part of the perimeter edge portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (the left side portion in  FIG.  37   ) overlaps with another part of the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (the right side portion in  FIG.  37   ). That is, another part of the red electron transport layer  33   r  overlaps with another part of the blue electron transport layer  33   b  with the blue light-emitting layer  35   b  interposed therebetween. 
     As a result of such superimposition, unlike the configurations according to the first and second embodiments described above, in the configuration according to the third embodiment, the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  are in contact with each other. 
     Note that, although not illustrated, any portion of the perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g  overlaps with at least one of the perimeter edge portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b , and the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r . Similarly, any portion of the perimeter edge portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  overlaps with at least one of the perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g , and the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r , and any portion of the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r  overlaps with at least one of the perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g , and the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r.    
     By such superposition, a part of the side surface of the green electron transport layer  33   g  is covered with the blue electron transport layer  33   b  or the red electron transport layer  33   r . This coating prevents direct contact between the green electron transport layer  33   g  and a hole transport layer  37 , and thus a leakage current between a cathode  25  and an anode  22  which are a green pixel electrode PEg is reduced. Furthermore, the other portion of the side surface of the green electron transport layer  33   g  is covered with the red electron transport layer  33   r . This coating similarly reduces a leakage current between the cathode  25  and the anode  22  which are the green pixel electrode PEg. Furthermore, a part of the side surface of the blue electron transport layer  33   b  is covered with the red electron transport layer  33   r . This coating similarly reduces a leakage current between a cathode  25  and an anode  22  which are a blue pixel electrode PEb. Thus, as compared to the method for manufacturing the display device  2  according to the first embodiment described above, the method for manufacturing the display device  2  according to the third embodiment can further improve the luminous efficiency of the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. This can reduce power consumption of the display device  2 . 
     Similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the third embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, it is possible to improve reliability of the display device  2 . Furthermore, the number of steps of the method for manufacturing the display device  2  can be reduced. Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration between the configuration according to the first embodiment described above and the configuration according to the third embodiment is also included in the scope of the disclosure. Furthermore, as to the order in which the perimeter edge portions overlap, any order may be acceptable. For example, superimposition may be in the order of green, red, and blue, blue, green, and red, blue, red, and green, red, green, and blue, or red, blue, and green. 
     Fourth Embodiment 
       FIG.  38    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a fourth embodiment of the disclosure. 
     As illustrated in  FIG.  38   , a green light-emitting layer  35   g  covers an entire side surface of a green electron transport layer  33   g , a blue light-emitting layer  35   b  covers an entire side surface of a blue electron transport layer  33   b , and a red light-emitting layer  35   r  covers an entire side surface of a red electron transport layer  33   r . Furthermore, a portion of the blue electron transport layer  33   b  overlaps with a portion of the green electron transport layer  33   g  with the green light-emitting layer  35   g  interposed therebetween, a portion of the red electron transport layer  33   r  overlaps with another portion of the green electron transport layer  33   g  with the green light-emitting layer  35   g  interposed therebetween, and another portion of the red electron transport layer  33   r  overlaps with another portion of the blue electron transport layer  33   b  with the blue light-emitting layer  35   b  interposed therebetween. 
     As illustrated in  FIG.  38   , the light-emitting element layer  5  according to the fourth embodiment has the same configuration as the light-emitting element layer  5  according to the second embodiment described above except the following three points. One point is a point where a part of perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (a left side portion in  FIG.  37   ) overlaps with a part of perimeter edge portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (a right side portion of  FIG.  37   ). Another point is a point where another part of the perimeter edge portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (the right side portion in  FIG.  37   ) overlaps with a part of the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (the left side portion in  FIG.  37   ). Still another point is a point where another part of the perimeter edge portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (the left side portion in  FIG.  37   ) overlaps with another part of the perimeter edge portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (the right side portion in  FIG.  37   ). 
     As illustrated in  FIG.  38   , the light-emitting element layer  5  according to the fourth embodiment has the same configuration as the light-emitting element layer  5  according to the third embodiment described above except that a side surface of the green electron transport layer  33   g  is covered with the green light-emitting layer  35   g , a side surface of the blue electron transport layer  33   b  is covered with the blue light-emitting layer  35   b , and a side surface of the red electron transport layer  33   r  is covered with the red light-emitting layer  35   r . Note that, similarly to the configurations according to the first and second embodiments described above, in the configuration according to the fourth embodiment, this coating separates the green electron transport layer  33   g , the blue electron transport layer  33   b , and the red electron transport layer  33   r  from each other. 
     That is, the configuration according to the fourth embodiment is a configuration obtained by combining the configuration according to the second embodiment described above to the configuration according to the third embodiment described above. Thus, as compared to the method for manufacturing the display device  2  according to the first embodiment, the method for manufacturing the display device  2  according to the fourth embodiment can further improve the reliability of the display device  2 , and can reduce the power consumption of the display device  2 . 
     Similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the fourth embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, the number of steps of the method for manufacturing the display device  2  can be reduced. Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration between the configurations according to the first, second, and third embodiments described above and the configuration according to the fourth embodiment is also included in the scope of the disclosure. 
     Fifth Embodiment 
     Configuration of Light-Emitting Element Layer 
       FIG.  39    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a fifth embodiment of the disclosure. As illustrated in  FIG.  39   , the light-emitting element layer  5  according to the present embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except that an insulating reverse tapered edge cover  123  is provided instead of the edge cover  23 . 
     The reverse tapered edge cover  123  according to the present embodiment has the same configuration as the edge cover  23  according to the first embodiment described above except that inclination of the side surface is reversed. The reverse tapered edge cover  123  covering a perimeter edge portion of a green pixel electrode PEg is formed in such a manner that an angle formed between a side surface of the reverse tapered edge cover  123  on the green pixel electrode PEg side and a surface of the green pixel electrode PEg is an acute angle. Similarly, the reverse tapered edge cover  123  covering a perimeter edge portion of a blue pixel electrode PEb is formed in such a manner that an angle formed between a side surface of the reverse tapered edge cover  123  on the blue pixel electrode PEb side and a surface of the blue pixel electrode PEb is an acute angle. Similarly, the reverse tapered edge cover  123  covering a perimeter edge portion of a red pixel electrode PEr is formed in such a manner that an angle formed between a side surface of the reverse tapered edge cover  123  on the red pixel electrode PEr side and a surface of the red pixel electrode PEr is an acute angle. 
     The reverse tapered edge cover  123  covers side surfaces of a green electron transport layer  33   g , a blue electron transport layer  33   b , and a red electron transport layer  33   r.    
     By such a coating, the side surface of the green electron transport layer  33   g  is not exposed to the etching solution  56  in step S 35 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and performance deterioration of the perimeter edge portion of the green electron transport layer  33   g . Similarly, the side surface of the green electron transport layer  33   g  and the side surface of the blue electron transport layer  33   b  are not exposed to the etching solution  56  in step S 41 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and the blue electron transport layer  33   b  and performance deterioration of the perimeter edge portions of the green electron transport layer  33   g  and the blue electron transport layer  33   b . Thus, the method for manufacturing the display device  2  according to the fifth embodiment can further improve the reliability of the display device  2  as compared to the method for manufacturing the display device  2  according to the first embodiment described above. 
     Furthermore, this coating prevents direct contact between the green electron transport layer  33   g  and a hole transport layer  37 , and thus reduces a leakage current between a cathode  25  and an anode  22  which are the green pixel electrode PEg. Similarly, this coating reduces a leakage current between a cathode  25  and an anode  22  which are the blue pixel electrode PEb, and reduces a leakage current between a cathode  25  and an anode  22  which are the red pixel electrode PEr. Thus, as compared to the method for manufacturing the display device  2  according to the first embodiment, the method for manufacturing the display device  2  according to the fifth embodiment can further improve the luminous efficiency of the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. This can reduce power consumption of the display device  2 . 
     Similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the fifth embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, the number of steps of the method for manufacturing the display device  2  can be reduced. Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Light-Emitting Element Layer Forming Process 
     Hereinafter, with reference to  FIGS.  40  to  47   , a process for forming the light-emitting element layer  5  (step S 4  in  FIG.  1   ) in the method for manufacturing the display device  2  according to the fifth embodiment of the disclosure will be described.  FIG.  40    is a flowchart illustrating an example of the process for forming the light-emitting element layer  5  illustrated in  FIG.  39   .  FIGS.  40  to  47    are schematic cross-sectional views illustrating portions of the example of the process for forming the light-emitting element layer  5  illustrated in  FIG.  39   . 
     The process according to the fifth embodiment illustrated in  FIG.  40    has the same steps in the same order as the process according to the first embodiment described above illustrated in  FIG.  4    except that step S 122  is performed instead of step S 22 . 
     As illustrated in  FIG.  40    and  FIG.  41   , following step S 21 , the reverse tapered edge cover  123  is formed so as to cover an edge of each cathode  25  (bank forming step) (step S 122 ). Subsequently, an electron injection layer  31  is formed to cover the cathodes  25  (step S 23 ). In step S 23 , the electron injection layer  31  is not formed on the side surface of the reverse tapered edge cover  123 . Thus, the electron injection layer  31  is step-cut and formed on the cathode  25  and on the reverse tapered edge cover  123 . 
     As illustrated in  FIG.  40    and  FIGS.  42  to  43   , subsequently, the green electron transport layer  33   g  is similarly step-cut to be formed (step S 25 ), and a green coating liquid  34   g  is step-cut to be applied (step S 26 ). Then, as illustrated in  FIG.  40    and  FIG.  44   , the green coating liquid  34   g  is exposed in such a manner that a portion to be the green light-emitting layer  35   g  is cured and the other portion is not cured (step S 27 ). 
     As illustrated in  FIGS.  40    and  FIGS.  45  to  46   , subsequently, the green light-emitting layer  35   g  is developed (step S 28 ), and the green electron transport layer  33   g  is etched (step S 29 ). In steps after step S 27 , the side surface of the green electron transport layer  33   g  is covered with the reverse tapered edge cover  123 , and the upper surface of the green electron transport layer  33   g  is covered with the green light-emitting layer  35   g . This can prevent side etching and performance deterioration of the green electron transport layer  33   g.    
     As illustrated in  FIG.  40    and  FIG.  47   , similarly, step S 30  including steps S 31  to S 35  and step S 36  including steps S 37  to S 41  are performed. In steps after step S 33 , the side surface of the blue electron transport layer  33   b  is covered with the reverse tapered edge cover  123 , and the upper surface of the blue electron transport layer  33   b  is covered with the blue light-emitting layer  35   b . This can prevent side etching and performance deterioration of the blue electron transport layer  33   b . In steps after step S 39 , the side surface of the red electron transport layer  33   r  is covered with the reverse tapered edge cover  123 , and the upper surface of the red electron transport layer  33   r  is covered with the red light-emitting layer  35   r . This can prevent side etching and performance deterioration of the red electron transport layer  33   r.    
     Then, as illustrated in  FIG.  40   , the hole transport layer  37  is formed (step S 42 ), and the anode  22  is formed (step S 43 ). 
     Sixth Embodiment 
     Configuration of Light-Emitting Element Layer 
       FIG.  48    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a sixth embodiment of the disclosure. As illustrated in  FIG.  48   , the light-emitting element layer  5  according to the sixth embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except that an edge cover  223  is provided instead of the edge cover  23 . The edge cover  223  is formed in an upper layer above a green light-emitting layer  35   g , a blue light-emitting layer  35   b , and a red light-emitting layer  35   r  and has insulating properties. 
     The edge cover  223  according to the sixth embodiment has the same configuration as the edge cover  23  according to the first embodiment described above except that the edge cover  223  covers a perimeter edge portion of the green light-emitting layer  35   g , a perimeter edge portion of the blue light-emitting layer  35   b , and a perimeter edge portion of the red light-emitting layer  35   r.    
     The edge cover  223  covers side surfaces of a green electron transport layer  33   g , a blue electron transport layer  33   b , and a red electron transport layer  33   r . Thus, the edge cover  223  according to the sixth embodiment is less likely to generate an abnormal electric field and an abnormal current in the periphery. 
     By such a coating, the side surface of the green electron transport layer  33   g  is not exposed to the etching solution  56  in step S 35 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and performance deterioration of the perimeter edge portion of the green electron transport layer  33   g . Similarly, the side surface of the green electron transport layer  33   g  and the side surface of the blue electron transport layer  33   b  are not exposed to the etching solution  56  in step S 41 , and thus it is possible to prevent unintended side etching of the green electron transport layer  33   g  and the blue electron transport layer  33   b  and performance deterioration of the perimeter edge portions of the green electron transport layer  33   g  and the blue electron transport layer  33   b . Thus, as compared to the method for manufacturing the display device  2  according to the first embodiment, the method for manufacturing the display device  2  according to the sixth embodiment can further improve the reliability of the display device  2 . 
     Furthermore, this coating prevents direct contact between the green electron transport layer  33   g  and a hole transport layer  37 , and thus reduces a leakage current between a cathode  25  and an anode  22  which are a green pixel electrode PEg. Similarly, this coating reduces a leakage current between a cathode  25  and an anode  22  which are a blue pixel electrode PEb, and reduces a leakage current between a cathode  25  and an anode  22  which are a red pixel electrode PEr. Thus, as compared to the method for manufacturing the display device  2  according to the sixth embodiment, the method for manufacturing the display device  2  according to the fifth embodiment described above can further improve the luminous efficiency of the green subpixel Pg, the blue subpixel Pb, and the red subpixel Pr. This can reduce power consumption of the display device  2 . 
     Similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the sixth embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, the number of steps of the method for manufacturing the display device  2  can be reduced. Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Light-Emitting Element Layer Forming Process 
     Hereinafter, with reference to  FIGS.  49  to  52   , a process for forming the light-emitting element layer  5  (step S 4  in  FIG.  1   ) in the method for manufacturing the display device  2  according to the sixth embodiment of the disclosure will be described.  FIG.  49    is a flowchart illustrating an example of a process for forming the light-emitting element layer  5  illustrated in  FIG.  48   .  FIGS.  50  to  52    are schematic cross-sectional views illustrating portions of the example of the process for forming the light-emitting element layer  5  illustrated in  FIG.  48   . 
     The process according to the sixth embodiment illustrated in  FIG.  49    has the same steps in the same order as the process according to the first embodiment illustrated in  FIG.  4    except that step S 22  is performed after steps S 24 , S 30  and S 36 , and before step S 42 . 
     As illustrated in  FIG.  49    and  FIG.  50   , following formation of the cathode  25  (step S 21 ), an electron injection layer is formed without forming the edge cover (step S 24 ), and formation of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (step S 24 ), formation of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (step S 30 ), and formation of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (step S 36 ) are further performed. 
     Then, as illustrated in  FIG.  49    and  FIG.  51   , the edge cover  223  is formed so as to cover the perimeter edge portion of the green light-emitting layer  35   g , the perimeter edge portion of the blue light-emitting layer  35   b , and the perimeter edge portion of the red light-emitting layer  35   r  (step S 22 ). 
     Then, as illustrated in  FIG.  49   , the hole transport layer  37  is formed (step S 42 ), and the anode  22  is formed (step S 43 ). 
     Seventh Embodiment 
       FIG.  52    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a seventh embodiment of the disclosure. 
     As illustrated in  FIG.  52   , the light-emitting element layer  5  according to the seventh embodiment has the same configuration as the light-emitting element layer  5  according to the second embodiment described above except that an edge cover  223  formed in an upper layer above a green light-emitting layer  35   g , a blue light-emitting layer  35   b , and a red light-emitting layer  35   r  is provided. 
     As illustrated in  FIG.  52   , the light-emitting element layer  5  according to the seventh embodiment has the same configuration as the light-emitting element layer  5  according to the sixth embodiment described above except that a side surface of a green electron transport layer  33   g  is covered with the green light-emitting layer  35   g , a side surface of a blue electron transport layer  33   b  is covered with the blue light-emitting layer  35   b , and a side surface of a red electron transport layer  33   r  is covered with the red light-emitting layer  35   r.    
     That is, the configuration according to the seventh embodiment is a configuration obtained by combining the configuration according to the second embodiment described above to the configuration according to the sixth embodiment described above. Thus, the method for manufacturing the display device  2  according to the seventh embodiment can exhibit the same effects as those of the methods for manufacturing the display device  2  according to the second and sixth embodiments described above. 
     Note that an intermediate configuration between the configuration according to the sixth embodiment described above and the configuration according to the seventh embodiment is also included in the scope of the disclosure. 
     Eighth Embodiment 
     Configuration of Light-Emitting Element Layer 
       FIG.  53    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to an eighth embodiment of the disclosure. As illustrated in  FIG.  53   , the light-emitting element layer  5  according to the eighth embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except that no edge cover is provided. Thus, it is possible to further reduce the number of steps of the method for manufacturing the display device  2  according to the eighth embodiment as compared to the method for manufacturing the display device  2  according to the first embodiment described above. 
     Further, similarly to the method for manufacturing the display device  2  according to the first embodiment described above, according to the method for manufacturing the display device  2  according to the eighth embodiment, the resolution and/or yield of the display device  2  can be improved. Furthermore, it is possible to further improve the reliability of the display device  2 . Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     No edge cover is formed between a green electron transport layer  33   g  and a green light-emitting layer  35   g  and between a blue electron transport layer  33   b  and a blue light-emitting layer  35   b  in the light-emitting element layer  5  according to the eighth embodiment. Thus, between these, as illustrated in  FIG.  53   , only a hole transport layer  37  is formed, or, although not illustrated, only both the hole transport layer  37  and an anode  22  are formed, or only the anode  22  is formed. 
     Light-Emitting Element Layer Forming Process 
     Hereinafter, with reference to  FIG.  54   , a process for forming the light-emitting element layer  5  (step S 4  in  FIG.  1   ) in the method for manufacturing the display device  2  according to the eighth embodiment of the disclosure will be described.  FIG.  54    is a flowchart illustrating the process for forming the light-emitting element layer  5  illustrated in  FIG.  53   . 
     The process according to the eighth embodiment illustrated in  FIG.  54    has the same steps in the same order as the process according to the first embodiment described above illustrated in  FIG.  4    except that step S 22  is not included. 
     Thus, as illustrated in  FIG.  54    and  FIG.  50   , similarly to the sixth embodiment described above, following formation of a cathode  25  (step S 21 ), an electron injection layer is formed without forming an edge cover (step S 24 ), and formation of the green electron transport layer  33   g  and the green light-emitting layer  35   g  (step S 24 ), formation of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b  (step S 30 ), and formation of the red electron transport layer  33   r  and the red light-emitting layer  35   r  (step S 36 ) are further performed. 
     Then, as illustrated in  FIG.  54   , the hole transport layer  37  is formed without forming an edge cover (step S 42 ), and the anode  22  is formed (step S 43 ). 
     The process according to the eighth embodiment does not include the step of forming the edge cover as compared to the processes according to the first to seventh embodiments described above, and thus can further reduce the number of steps in manufacturing the display device. 
     Ninth Embodiment 
       FIG.  55    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a ninth embodiment of the disclosure. 
     As illustrated in  FIG.  55   , the light-emitting element layer  5  according to the ninth embodiment has the same configuration as the light-emitting element layer  5  according to the second embodiment described above except that no edge cover is provided. 
     As illustrated in  FIG.  55   , the light-emitting element layer  5  according to the ninth embodiment has the same configuration as the light-emitting element layer  5  according to the eighth embodiment described above except that a side surface of a green electron transport layer  33   g  is covered with a green light-emitting layer  35   g , a side surface of a blue electron transport layer  33   b  is covered with a blue light-emitting layer  35   b , and a side surface of a red electron transport layer  33   r  is covered with a red light-emitting layer  35   r.    
     That is, the configuration according to the ninth embodiment is a configuration obtained by combining the configuration according to the second embodiment described above to the configuration according to the eighth embodiment described above. Thus, it is possible to further reduce the number of steps of the method for manufacturing the display device  2  according to the ninth embodiment as compared to the method for manufacturing the display device  2  according to the second embodiment described above. 
     Similarly to the method for manufacturing the display device  2  according to the second embodiment described above, according to the method for manufacturing the display device  2  according to the ninth embodiment, the resolution and/or yield of the display device  2  can be improved. It is possible to further improve the reliability of the display device  2 . Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration between the configuration according to the eighth embodiment described above and the configuration according to the ninth embodiment is also included in the scope of the disclosure. 
     Tenth Embodiment 
     Configuration of Light-Emitting Element Layer 
       FIG.  56    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a tenth embodiment of the disclosure. 
     As illustrated in  FIG.  56   , the light-emitting element layer  5  according to the tenth embodiment has the same configuration as the light-emitting element layer  5  according to the third embodiment described above except that no edge cover is provided. 
     As illustrated in  FIG.  56   , the light-emitting element layer  5  according to the tenth embodiment has the same configuration as the light-emitting element layer  5  according to the eighth embodiment described above except that end portions of a green electron transport layer  33   g  and a green light-emitting layer  35   g  overlap with end portions of a blue electron transport layer  33   b  and a blue light-emitting layer  35   b , end portions of the green electron transport layer  33   g  and the green light-emitting layer  35   g  overlap with end portions of a red electron transport layer  33   r  and a red light-emitting layer  35   r , and end portions of the red electron transport layer  33   r  and the red light-emitting layer  35   r  overlap with end portions of the blue electron transport layer  33   b  and the blue light-emitting layer  35   b.    
     That is, the configuration according to the tenth embodiment is a configuration obtained by combining the configuration according to the third embodiment described above to the configuration according to the eighth embodiment described above. Thus, it is possible to further reduce the number of steps of the method for manufacturing the display device  2  according to the tenth embodiment as compared to the method for manufacturing the display device  2  according to the third embodiment described above. 
     Similarly to the method for manufacturing the display device  2  according to the third embodiment described above, according to the method for manufacturing the display device  2  according to the tenth embodiment, the resolution and/or yield of the display device  2  can be improved. It is possible to improve the reliability of the display device  2 . Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration between the configuration according to the eighth embodiment described above and the configuration according to the tenth embodiment is also included in the scope of the disclosure. 
     Forming Pattern of Light-Emitting Layer 
       FIG.  57    is a plan view illustrating an example of an arrangement pattern of green pixel electrodes PEg, blue pixel electrodes PEb, and red pixel electrodes PEr.  FIG.  58    is a plan view illustrating an example of a forming pattern of the green light-emitting layer  35   g  illustrated in  FIG.  56    in a case of the arrangement pattern illustrated in  FIG.  56   .  FIG.  59    is a plan view illustrating an example of a forming pattern of the blue light-emitting layer  35   b  illustrated in  FIG.  56    in the case of the arrangement pattern illustrated in  FIG.  56   .  FIG.  60    is a plan view illustrating an example of a forming pattern of the red light-emitting layer  35   r  illustrated in  FIG.  56    in the case of the arrangement pattern illustrated in  FIG.  56   . 
     As illustrated in  FIG.  56   , the green light-emitting layer  35   g  according to the tenth embodiment is preferably a layer common to a plurality of adjacent green subpixels Pg (a plurality of adjacent subpixels of the same color). The green light-emitting layer  35   g  overlaps with the entire green pixel electrodes PEg. Preferably, the green light-emitting layer  35   g  includes openings GK overlapping with the blue pixel electrodes PEb and openings gK overlapping with the red pixel electrodes PEr, and is formed over the entire display region. As an example, in a case where the green pixel electrodes PEg, the blue pixel electrodes PEb, and the red pixel electrodes PEr are arranged in a PenTile manner as illustrated in  FIG.  57   , the green light-emitting layer  35   g  is preferably formed as illustrated in  FIG.  58   . The openings GK overlapping with the blue pixel electrodes PEb each are open to the inside of the perimeter edge portion of each of the blue pixel electrodes PEb, and the green light-emitting layer  35   g  overlaps with the entire circumference of the perimeter edge portion of each of the blue pixel electrodes PEb. The openings gK overlapping with the red pixel electrodes PEr each are open to the inside of the perimeter edge portion of each of the red pixel electrodes PEr, and the green light-emitting layer  35   g  overlaps with the entire circumference of the perimeter edge portion of each of the red pixel electrodes PEr. 
     Similarly, the blue light-emitting layer  35   b  according to the tenth embodiment is preferably a layer common to a plurality of adjacent blue subpixels Pb (a plurality of adjacent subpixels of the same color). The blue light-emitting layer  35   b  overlaps with the entire blue pixel electrodes PEb. The blue light-emitting layer  35   b  includes openings bk overlapping with the green pixel electrodes PEg and openings BK overlapping with the red pixel electrodes PEr, and is preferably formed over the entire display region. As an example, in a case where the green pixel electrodes PEg, the blue pixel electrodes PEb, and the red pixel electrodes PEr are arranged in the PenTile manner as illustrated in  FIG.  57   , the blue light-emitting layer  35   b  is preferably formed as illustrated in  FIG.  59   . The openings bk overlapping with the green pixel electrodes PEg each are open to the inside of the perimeter edge portion of each of the green pixel electrodes PEg, and the blue light-emitting layer  35   b  overlaps with the entire circumference of the perimeter edge portion of each of the green pixel electrodes PEg. The openings BK overlapping with the red pixel electrodes PEr each are open to the inside of the perimeter edge portion of each of the red pixel electrodes PEr, and the blue light-emitting layer  35   b  overlaps with the entire circumference of the perimeter edge portion of each of the red pixel electrodes PEr. 
     Similarly, the red light-emitting layer  35   r  according to the tenth embodiment is preferably a layer common to a plurality of adjacent red subpixels Pr (a plurality of adjacent subpixels of the same color). The red light-emitting layer  35   r  overlaps with the entire red pixel electrodes PEr. The red light-emitting layer  35   r  includes openings rk overlapping with the green pixel electrodes PEg and openings RK overlapping with the blue pixel electrodes PEb, and is preferably formed over the entire display region. As an example, in a case where the green pixel electrodes PEg, the blue pixel electrodes PEb, and the red pixel electrodes PEr are arranged in the Pen Tile manner as illustrated in  FIG.  57   , the red light-emitting layer  35   r  is preferably formed as illustrated in  FIG.  60   . The openings rk overlapping with the green pixel electrodes PEg each are open to the inside of the perimeter edge portion of each of the green pixel electrodes PEg, and the red light-emitting layer  35   r  overlaps with the entire circumference of the perimeter edge portion of each of the green pixel electrodes PEg. The openings RK overlapping with the blue pixel electrodes PEb each are open to the inside of the perimeter edge portion of each of the blue pixel electrodes PEb, and the red light-emitting layer  35   r  overlaps with the entire circumference of the perimeter edge portion of each of the blue pixel electrodes PEb. 
     As a result of these, the three light-emitting layers  35   g ,  35   b , and  35   r  overlap with perimeter edge portions of the respective pixel electrodes PEr, PEg, and PEb and function as edge covers. Furthermore, such a forming pattern of the light-emitting layers can also be applied to the third and fourth embodiments described above and an eleventh embodiment described below. 
     Eleventh Embodiment 
       FIG.  61    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to an eleventh embodiment of the disclosure. 
     As illustrated in  FIG.  61   , the light-emitting element layer  5  according to the eleventh embodiment has the same configuration as the light-emitting element layer  5  according to the fourth embodiment described above except that no edge cover is provided. 
     As illustrated in  FIG.  61   , the light-emitting element layer  5  according to the eleventh embodiment has the same configuration as the light-emitting element layer  5  according to the tenth embodiment described above except that a side surface of a green electron transport layer  33   g  is covered with a green light-emitting layer  35   g , a side surface of a blue electron transport layer  33   b  is covered with a blue light-emitting layer  35   b , and a side surface of a red electron transport layer  33   r  is covered with a red light-emitting layer  35   r.    
     That is, the configuration according to the eleventh embodiment is a configuration obtained by combining the configuration according to the fourth embodiment described above to the configuration according to the tenth embodiment described above. Thus, the configuration according to the eleventh embodiment is a configuration obtained by combining the configuration according to the third embodiment described above to the configuration according to the eighth embodiment described above and further combining the second embodiment described above. Thus, it is possible to further reduce the number of steps of the method for manufacturing the display device  2  according to the eleventh embodiment as compared to the method for manufacturing the display device  2  according to the fourth embodiment described above. 
     Similarly to the method for manufacturing the display device  2  according to the third embodiment described above, according to the method for manufacturing the display device  2  according to the eleventh embodiment, the resolution and/or yield of the display device  2  can be improved. It is possible to further improve the reliability of the display device  2 . Furthermore, color gamut of the display device  2  can be improved. Furthermore, power consumption of the display device  2  can be reduced. 
     Note that an intermediate configuration of the configurations according to the eighth, ninth, and tenth embodiments and the configuration according to the eleventh embodiment is also included within the scope of the disclosure. 
     Similarly to the green light-emitting layer  35   g  according to the tenth embodiment, the green light-emitting layer  35   g  according to the eleventh embodiment includes openings GK overlapping with blue pixel electrodes PEb and openings gK overlapping with red pixel electrodes PEr, and is preferably formed over the entire display region. 
     Similarly to the blue light-emitting layer  35   b  according to the tenth embodiment, the blue light-emitting layer  35   b  according to the eleventh embodiment includes openings bk overlapping with green pixel electrodes PEg and openings BK overlapping with the red pixel electrodes PEr, and is preferably formed over the entire display region. 
     Similarly to the red light-emitting layer  35   r  according to the tenth embodiment, a red light-emitting layer  35   b  according to the eleventh embodiment includes openings rk overlapping with the green pixel electrodes PEg and openings RK overlapping with the blue pixel electrodes PEb, and is preferably formed over the entire display region. 
     Twelfth Embodiment 
       FIG.  62    is a cross-sectional view illustrating a schematic configuration of a light-emitting element layer  5  in a display device  2  according to a twelfth embodiment of the disclosure. 
     As illustrated in  FIG.  62   , the light-emitting element layer  5  according to the present embodiment has the same configuration as the light-emitting element layer  5  according to the first embodiment described above except for the following three points. One point is that the layering order in an active layer  24  is inverted in such a manner that layering occurs in the order of an anode  22  to a cathode  25 . Another point is that along with the inversion of the layering order, the active layer  24  includes (i) a hole injection layer  45  formed in a solid shape, (ii) a green hole transport layer  37   g  formed in an island shape in a green subpixel Pg, (iii) a blue hole transport layer  37   b  formed in an island shape in a blue subpixel Pb, (iv) a red hole transport layer  37   r  formed in an island shape in a red subpixel Pr, and (v) an electron transport layer  33  formed in a solid shape. Still another point is that along with the inversion of the layering order, the anode  22  is formed as a green pixel electrode PEg, a blue pixel electrode PEb, and a red pixel electrode PEr, and the cathode  25  is formed as a common electrode. 
     A green light-emitting layer  35   g  is in direct contact with the green hole transport layer  37   g , and covers the entire upper surface of the green hole transport layer  37   g.    
     The green hole transport layer  37   g  is composed of a hole transport material that can be etched using the etching solution  56  that does not erode the green light-emitting layer  35   g  (i.e., a cured green photosensitive resin  43   g ). The photosensitive resin after curing is often insoluble in an organic solvent such as toluene or chlorobenzene. Thus, the etching solution  56  is preferably an organic solvent in which the green photosensitive resin  43   g  is insoluble. In this case, the green hole transport layer  37   g  is composed of a light curable hole transport material soluble in an organic solvent in which the green photosensitive resin  43   g  is insoluble. Such a hole transport material is, for example, a polymer of a compound represented by Chemical Formula (1) below (so-called “OTPD”), and a polymer of a compound represented by Chemical Formula (2) below (so-called “DHTBOX”). For example, the polymer of DHTBOX is represented by Chemical Formula (3) below. 
     
       
         
         
             
             
         
       
     
     Monomers of OPTD and DHTBOX have an oxetanyl group that is a 4-membered cyclic ether group. As a result, the monomers of OPTD and DHTBOX are subjected to ring-opening polymerization by ultraviolet irradiation or heating, and cross-linked in three dimensions and cured to form a polymer. Thus, the method of curing a forming material of the green hole transport layer  37   g  may be exposure treatment, heat treatment, or both of the exposure treatment and the heat treatment. For example, the green hole transport layer  37   g  may be cured to be formed by the exposure treatment, a green coating liquid  34   g  may be applied, the green hole transport layer  37   g  may be etched, and then the green hole transport layer  37   g  may be additionally cured by the heat treatment. For example, the green hole transport layer  37   g  may be cured to be formed by the exposure treatment, the green hole transport layer  37   g  may be additionally cured by the heat treatment, and then the green coating liquid  34   g  may be applied. Furthermore, as necessary, for example, a diaryliodonium-based cation initiator as represented by Chemical Formula (4) below, for example, an anion initiator as represented by Chemical Formula (5) below, and a photopolymerization initiator such as a radical initiator may be added to the forming material of the green hole transport layer  37   g . 
     
       
         
         
             
             
         
       
     
     A blue light-emitting layer  35   b  is in direct contact with a blue hole transport layer  37   b , and covers the entire upper surface of the blue hole transport layer  37   b.    
     The blue hole transport layer  37   b  is composed of a hole transport material that can be etched using the etching solution  56  that does not erode the blue light-emitting layer  35   b  (i.e., a cured blue photosensitive resin  43   b ). The photosensitive resin after curing is often insoluble in an organic solvent such as toluene or chlorobenzene. Thus, the etching solution  56  is preferably an organic solvent in which the blue photosensitive resin  43   b  is insoluble. In this case, the blue hole transport layer  37   b  is composed of a light curable hole transport material soluble in an organic solvent in which the blue photosensitive resin  43   b  is insoluble. Such a hole transport material is, for example, a polymer of OTPD and DHTBOX. 
     The method of curing a forming material of the blue hole transport layer  37   b  may be exposure treatment, heat treatment, or both of the exposure treatment and the heat treatment. For example, the blue hole transport layer  37   b  may be cured to be formed by the exposure treatment, a blue coating liquid  34   b  may be applied, the blue hole transport layer  37   b  may be etched, and then the blue hole transport layer  37   b  may be additionally cured by the heat treatment. For example, the blue hole transport layer  37   b  may be cured to be formed by the exposure treatment, the blue hole transport layer  37   b  may be additionally cured by the heat treatment, and then the blue coating liquid  34   b  may be applied. Furthermore, as necessary, a photopolymerization initiator as described above may be added to the forming material of the blue hole transport layer  37   b.    
     The red light-emitting layer  35   r  is in direct contact with the red hole transport layer  37   r , and covers the entire upper surface of the red hole transport layer  37   r.    
     The red hole transport layer  37   r  is composed of a hole transport material that can be etched using the etching solution  56  that does not erode the red light-emitting layer  35   r  (i.e., a cured red photosensitive resin  43   r ). The photosensitive resin after curing is often insoluble in an organic solvent such as toluene or chlorobenzene. Thus, the etching solution  56  is preferably an organic solvent in which the red photosensitive resin  43   r  is insoluble. In this case, the red hole transport layer  37   r  is composed of a light curable hole transport material soluble in an organic solvent in which the red photosensitive resin  43   r  is insoluble. Such a hole transport material is, for example, a polymer of OTPD and DHTBOX. 
     The method of curing a forming material of the red hole transport layer  37   r  may be exposure treatment, heat treatment, or both of the exposure treatment and the heat treatment. For example, the red hole transport layer  37   r  may be cured to be formed by curing due to the exposure treatment, a red coating liquid  34   r  may be applied, the red hole transport layer  37   r  may be etched, and then the red hole transport layer  37   r  may be additionally cured by the heat treatment. For example, the red hole transport layer  37   r  may be cured to be formed by the exposure treatment, the red hole transport layer  37   r  may be additionally cured by the heat treatment, and then the red coating liquid  34   r  may be applied. Further, the photopolymerization initiator as described above may be added to the forming material of the red hole transport layer  37   r , as necessary. 
     The green hole transport layer  37   g , the blue hole transport layer  37   b , and the red hole transport layer  37   r  are separated from each other. 
     The electron transport layer  33  is formed in a solid shape so as to cover the green light-emitting layer  35   g , the red light-emitting layer  35   r , and the blue light-emitting layer  35   b  (if exposed, the exposed portion of the hole injection layer  45  and the exposed portion of the edge cover  23 ). This is not a limitation, and the electron transport layer  33  need not be formed, or may be formed separately in an island shape for each subpixel so as to individually cover the green light-emitting layer  35   g , the red light-emitting layer  35   r , and the blue light-emitting layer  35   b , paired with the anode  22 . Furthermore, the electron transport layer  33  may have a multilayer structure. 
     Thus, the method for manufacturing the display device  2  according to the twelfth embodiment can exhibit the same effects as those of the method for manufacturing the display device  2  according to the first embodiment described above. 
     Note that a configuration obtained by similarly inverting the layering order in the active layer  24  in the configurations of the display device  2  according to the second to eleventh embodiments is also within the scope of the disclosure. 
     Supplement 
     A method for manufacturing a display device according to a first aspect of the disclosure is a method for manufacturing the display device including a substrate, a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer, and a second subpixel including a second pixel electrode provided on the substrate, the method including: forming the first charge transport layer on the first pixel electrode and the second pixel electrode; applying a first mixture obtained by mixing the first quantum dots and a photosensitive resin on the first charge transport layer; pattern-exposing the first mixture to cure a portion of the first mixture to be formed into the first light-emitting layer; removing an uncured portion of the first mixture; and etching the first charge transport layer with an etching solution using the first light-emitting layer as a mask, the etching solution being an alkaline solution or an organic solvent. 
     A method for manufacturing a display device according to a second aspect of the disclosure may be the method according to the first aspect in which in the etching of the first charge transport layer, the first charge transport layer is etched to remove a perimeter edge portion of a portion of the first charge transport layer, the portion being between the first light-emitting layer and the substrate. 
     A method for manufacturing a display device according to a third aspect of the disclosure may be the method according to the first aspect further including, before the forming of the first charge transport layer, forming a bank having insulating properties to cover a perimeter edge portion of the first pixel electrode, an angle formed between a side surface of the bank on the first pixel electrode side and a surface of the first pixel electrode being an acute angle. 
     A method for manufacturing a display device according to a fourth aspect of the disclosure may be the method according to any one of the first to third aspects in which the etching solution is an alkaline solution, and the removing of the first mixture and the etching of the first charge transport layer are performed in series in a single step or in parallel. 
     A method for manufacturing a display device according to a fifth aspect of the disclosure may be the method according to any one of the first to fourth aspects in which the second subpixel includes a second light-emitting layer including second quantum dots, and a second charge transport layer provided between the second pixel electrode and the second light-emitting layer and having the same polarity as the first charge transport layer, the method further including: forming the second charge transport layer on the first light-emitting layer and the second pixel electrode; applying a second mixture obtained by mixing the second quantum dots and a photosensitive resin on the second charge transport layer; pattern-exposing the second mixture to cure a portion of the second mixture to be formed into the second light-emitting layer; removing an uncured portion of the second mixture; and etching the second charge transport layer with the etching solution to expose at least partially the first light-emitting layer using the second light-emitting layer as a mask. 
     A display device according to a sixth aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer having second quantum dots, and a second charge transport layer provided between the second pixel electrode and the second light-emitting layer and having the same polarity as the first charge transport layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third charge transport layer provided between the third pixel electrode and the third light-emitting layer and having the same polarity as the first charge transport layer, the third subpixel being adjacent to the first subpixel, in which the first charge transport layer, the second charge transport layer, and the third charge transport layer are soluble in an etching solution which is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first charge transport layer, the second light-emitting layer is in direct contact with the second charge transport layer, the third light-emitting layer is in direct contact with the third charge transport layer, each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer includes a cured photosensitive resin that is insoluble in the etching solution, and the first charge transport layer, the second charge transport layer, and the third charge transport layer are separated from each other. 
     A display device according to a seventh aspect of the disclosure may be the display device according to the sixth aspect in which at least one light-emitting layer of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer covers at least a part of a side surface of a corresponding charge transport layer of the first charge transport layer, the second charge transport layer, and the third charge transport layer. 
     A display device according to an eighth aspect of the disclosure may be the display device according to the seventh aspect in which the first light-emitting layer covers at least a part of a side surface of the first charge transport layer, the second light-emitting layer covers at least a part of a side surface of the second charge transport layer, and the third light-emitting layer covers at least a part of a side surface of the third charge transport layer. 
     A display device according to a ninth aspect of the disclosure may be the display device according to any one of the sixth to eighth aspects further including: a common electrode provided on a side opposite to the first charge transport layer with respect to the first light-emitting layer, on a side opposite to the second charge transport layer with respect to the second light-emitting layer, and on a side opposite to the third charge transport layer with respect to the third light-emitting layer; and a fourth charge transport layer provided between the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer, and the common electrode and having a reverse polarity to the first charge transport layer, in which one or both of the common electrode and the fourth charge transport layer are formed between the first light-emitting layer and the second light-emitting layer, and between the first light-emitting layer and the third light-emitting layer. 
     A display device according to a tenth aspect of the disclosure may be the display device according to any one of the sixth to eighth aspects further including a bank having insulating properties and formed to cover a perimeter edge portion of the first light-emitting layer. 
     A display device according to an eleventh aspect of the disclosure may be the display device according to any one of the sixth to eighth aspects in which the first light-emitting layer covers an entire side surface of the first charge transport layer, a portion of the second charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed between the portion of the second charge transport layer and the portion of first charge transport layer, and a portion of the third charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed between the portion of the third charge transport layer and the portion of the first charge transport layer. 
     A display device according to a twelfth aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer including second quantum dots, and a second charge transport layer provided between the second pixel electrode and the second light-emitting layer and having the same polarity as the first charge transport layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third charge transport layer provided between the third pixel electrode and the third light-emitting layer and having the same polarity as the first charge transport layer, the third subpixel being adjacent to the first subpixel, in which the first charge transport layer, the second charge transport layer, and the third charge transport layer are soluble in an etching solution that is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first charge transport layer, the second light-emitting layer is in direct contact with the second charge transport layer, the third light-emitting layer is in direct contact with the third charge transport layer, each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer includes a cured photosensitive resin that is insoluble in the etching solution, a portion of the second charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed between the portion of the second charge transport layer and the portion of the first charge transport layer, and a portion of the third charge transport layer overlaps with a portion of the first charge transport layer with the first light-emitting layer interposed between the portion of the third charge transport layer and the portion of the first charge transport layer. 
     A display device according to a thirteenth aspect of the disclosure may be the display device according to the eleventh or twelfth aspect in which each of the first light-emitting layer, the second light-emitting layer, and the third light-emitting layer is a layer common to a plurality of adjacent subpixels of the same color, a portion of the third charge transport layer overlaps with a portion of the second charge transport layer with the second light-emitting layer interposed between the portion of the third charge transport layer and the portion of the second charge transport layer, the first light-emitting layer overlaps with the entire first pixel electrode, includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the second subpixel and overlaps with entire circumferences of the perimeter edge portions, and includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the third subpixel and overlaps with entire circumferences of the perimeter edge portions, the second light-emitting layer overlaps with the entire second pixel electrode, includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the first subpixel and overlaps with entire circumferences of the perimeter edge portions, and includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the third subpixel and overlaps with entire circumferences of the perimeter edge portions, and the third light-emitting layer includes an opening inside a perimeter edge portion of the first pixel electrode and overlaps with an entire circumference of the perimeter edge portion, includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the first subpixel and overlaps with entire circumferences of the perimeter edge portions, and includes openings inside perimeter edge portions of a plurality of pixel electrodes included in the subpixels of the same color as the second subpixel and overlaps entire circumferences of the perimeter edge portions. 
     A display device according to a fourteenth aspect of the disclosure may be the display device according to any one of the sixth to eighth and tenth to thirteenth aspects, further including a bank having insulating properties and formed to cover a perimeter edge portion of the first pixel electrode, an angle formed between a side surface of the bank on the first pixel electrode side and a surface of the first pixel electrode being an acute angle. 
     A display device according to a fifteenth aspect of the disclosure may be the display device according to any one of the sixth to fourteenth aspects in which the first charge transport layer, the second charge transport layer, and the third charge transport layer are different from each other in a film thickness or material. 
     A display device according to a sixteenth aspect of the disclosure may be the display device according to any one of the sixth to fifteenth aspects in which the etching solution is an alkaline solution. 
     A display device according to a seventeenth aspect of the disclosure has a configuration including: a substrate; a first subpixel including a first pixel electrode provided on the substrate, a first light-emitting layer including first quantum dots, and a first portion of a charge transport layer provided between the first pixel electrode and the first light-emitting layer; a second subpixel including a second pixel electrode provided on the substrate, a second light-emitting layer including second quantum dots, and a second portion of the charge transport layer provided between the second pixel electrode and the first light-emitting layer, the second subpixel being adjacent to the first subpixel; and a third subpixel including a third pixel electrode provided on the substrate, a third light-emitting layer including third quantum dots, and a third portion of the charge transport layer provided between the third pixel electrode and the third light-emitting layer, the third subpixel being adjacent to the first subpixel, in which the charge transport layer is soluble in an etching solution that is an alkaline solution or an organic solvent, the first light-emitting layer is in direct contact with the first portion of the charge transport layer, and includes a cured photosensitive resin that is insoluble in the etching solution, and each of the second portion and the third portion of the charge transport layer is thinner than the first portion of the charge transport layer. 
     The disclosure is not limited to each of the embodiments described above, and various modifications may be made within the scope of the claims. Embodiments obtained by appropriately combining technical approaches disclosed in each of the different embodiments also fall within the technical scope of the disclosure. Furthermore, novel technical features can be formed by combining the technical approaches disclosed in each of the embodiments.