Display device and method for manufacturing display device

Abstract

A display device (1) comprises: an island-shaped lower pixel electrode (3) configured from a central portion (3c) and a peripheral portion (3pc); an island-shaped upper pixel electrode (9) overlapping the central portion (3c) of the lower pixel electrode (3) in plan view and not overlapping the peripheral portion (3pc) of the lower pixel electrode (3) in plan view; a functional layer (8G) including a green light-emitting layer (6G) provided, between the lower pixel electrode (3) and the upper pixel electrode (9), in a size larger than the upper pixel electrode (9) in plan view; an insulating layer (10) having an opening (10k); and a common electrode (11) electrically connected a plurality of upper pixel electrodes (9) via a plurality of openings (10k). The average film thickness of a first portion (8G1) of the functional layer (8G) is different from the average film thickness of a second portion (8G2) of the functional layer (8G).

Description

Display device and method for manufacturing the same

[0001] The present disclosure relates to a display device and a method for manufacturing a display device.

[0002] In recent years, various display devices equipped with light-emitting elements have been developed, and in particular, display devices equipped with QLEDs (Quantum dot Light Emitting Diodes) or OLEDs (Organic Light Emitting Diodes) have attracted much attention because of their ability to achieve low power consumption, thinness, high image quality, and the like.

[0003] For example, Patent Document 1 describes a light-emitting device that includes banks that separate pixel regions and a light-emitting layer that is disposed within the pixel regions surrounded by the banks.

[0004] Japanese Patent Publication No. 2021-086769

[0005] However, the light-emitting layer provided in each of the multiple pixel regions of the light-emitting device described in Patent Document 1 has a film thickness defect at the periphery of the pixel region due to unevenness in the layer below the light-emitting layer, differences in wettability between the bank and the pixel region, the influence of convection of the solution that occurs during the drying process of the light-emitting layer, etc. In such a light-emitting device, even if the film thickness of the light-emitting layer is set to an optimal film thickness taking into account the light-emitting efficiency in the light-emitting region, the film thickness at the periphery of the pixel region is different from the optimal film thickness, which causes a problem of reduced light-emitting efficiency and lifespan of the light-emitting device.

[0006] An object of one aspect of the present disclosure is to provide a display device that can achieve high luminous efficiency and a long life, and a method for manufacturing the display device.

[0007] In order to solve the above-mentioned problems, the display device of the present disclosure includes: a display region including a plurality of pixels; an island-shaped lower pixel electrode provided for each of the plurality of pixels and configured with a central portion and a peripheral portion surrounding the central portion; an island-shaped upper pixel electrode provided for each of the plurality of pixels and overlapping with the central portion of the lower pixel electrode in a planar view but not overlapping with the peripheral portion of the lower pixel electrode in a planar view; a functional layer provided between the lower pixel electrode and the upper pixel electrode for each of the plurality of pixels and including a light-emitting layer that is larger than the upper pixel electrode in a planar view; an insulating layer that covers the spaces between each end of the plurality of upper pixel electrodes and has openings that do not cover a part of the top surface of each of the plurality of upper pixel electrodes opposite to the side on which the light-emitting layer is located; and a common electrode electrically connected to each of the plurality of upper pixel electrodes via each of the plurality of openings in the insulating layer, The functional layer includes a first portion that includes a portion of the light-emitting layer and overlaps with the central portion of the lower pixel electrode in a planar view, and a second portion that includes another portion of the light-emitting layer and overlaps with a portion of the peripheral portion of the lower pixel electrode that contacts the functional layer in a planar view, and the average film thickness of the first portion is different from the average film thickness of the second portion.

[0008] In order to solve the above-mentioned problems, the manufacturing method of the display device of the present disclosure includes: a lower pixel electrode forming step of forming an island-shaped lower pixel electrode; an upper pixel electrode forming step, which is a step performed after the lower pixel electrode forming step, of forming an island-shaped upper pixel electrode that overlaps a central portion of the lower pixel electrode in a planar view and does not overlap a peripheral portion surrounding the central portion of the lower pixel electrode in a planar view; a functional layer forming step, which is a step performed between the lower pixel electrode forming step and the upper pixel electrode forming step, of forming a functional layer between the lower pixel electrode and the upper pixel electrode, including a light-emitting layer forming step of forming a light-emitting layer that is larger than the upper pixel electrode in a planar view; an insulating layer forming step, which is a step performed after the upper pixel electrode forming step, of entirely forming an insulating layer that covers the upper pixel electrode; an opening forming step, which is a step performed after the insulating layer forming step, of forming an opening in a part of an upper surface of the upper pixel electrode opposite to the side where the light-emitting layer is located in the insulating layer; and a common electrode forming step, which is a step performed after the opening forming step, of forming a common electrode electrically connected to the upper pixel electrode via the opening in the insulating layer, In the functional layer formation process, a functional layer is formed that includes a first portion that includes a part of the light-emitting layer and overlaps the central portion of the lower pixel electrode in a planar view, and a second portion that includes another part of the light-emitting layer and overlaps the portion of the peripheral portion of the lower pixel electrode that contacts the functional layer in a planar view, and has an average film thickness that is different from the average film thickness of the first portion.

[0009] According to one aspect of the present disclosure, it is possible to provide a display device that can achieve high luminous efficiency and a long life, and a method for manufacturing the display device.

[0010] 1 is a plan view showing a schematic configuration of a display device of embodiment 1; FIG. 2 is a cross-sectional view showing a schematic configuration of a display region of the display device of embodiment 1; FIG. 3 is a plan view illustrating only a lower pixel electrode, an upper pixel electrode, and an insulating layer provided on a substrate of the display device of embodiment 1; FIG. 4 is a diagram for explaining a manufacturing method of the display device of embodiment 1; FIG. 5 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 2; FIG. 6 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 3; FIG. 7 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 4; FIG. 8 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 5; FIG. 9 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 6; FIG. 10 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 7; FIG. 11 is a cross-sectional view showing a schematic configuration of a display region of a display device of embodiment 8.

[0011] The following describes an embodiment of the present disclosure with reference to Figures 1 to 11. For the sake of convenience, components having the same functions as those described in a specific embodiment will be denoted by the same reference numerals, and their description may be omitted.

[0012] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0013] As shown in Fig. 1, the display device 1 includes a frame area NDA and a display area DA. The display area DA of the display device 1 includes a plurality of display units PIX, each of which includes a red pixel RSP, a green pixel GSP, and a blue pixel BSP. In this embodiment, a case where one display unit PIX is configured with a red pixel RSP, a green pixel GSP, and a blue pixel BSP will be described as an example, but this is not limiting. For example, one display unit PIX may include pixels of other colors in addition to the red pixel RSP, the green pixel GSP, and the blue pixel BSP.

[0014] Fig. 2 is a cross-sectional view showing a schematic configuration of the display area DA of the display device 1 of Embodiment 1. Fig. 3 is a plan view showing only the lower pixel electrode 3, the upper pixel electrode 9, and the insulating layer 10 provided on the substrate 2 of the display device 1 of Embodiment 1.

[0015] As shown in Figure 2, in the display area DA of the display device 1, a lower pixel electrode 3 and a bank 4, a first charge transport layer 5, a red light-emitting layer 6R, a green light-emitting layer 6G, a blue light-emitting layer 6B, a second charge transport layer 7, an upper pixel electrode 9, an insulating layer 10, and a common electrode 11 are provided on a substrate 2 in this order from the substrate 2 side.

[0016] The red pixel RSP provided in the display area DA of the display device 1 includes a red light-emitting element 30R, the green pixel GSP provided in the display area DA of the display device 1 includes a green light-emitting element 30G, and the blue pixel BSP provided in the display area DA of the display device 1 includes a blue light-emitting element 30B. The red light-emitting element 30R included in the red pixel RSP, a part of which is shown in Figure 2, includes a lower pixel electrode 3, a functional layer 8R including a first charge transport layer 5, a red light-emitting layer 6R, and a second charge transport layer 7, an upper pixel electrode 9, and a common electrode 11; the green light-emitting element 30G included in the green pixel GSP, shown in Figure 2, includes a lower pixel electrode 3, a functional layer 8G including a first charge transport layer 5, a green light-emitting layer 6G, and a second charge transport layer 7, an upper pixel electrode 9, and a common electrode 11; and the blue light-emitting element 30B included in the blue pixel BSP, a part of which is shown in Figure 2, includes a lower pixel electrode 3, a functional layer 8B including a first charge transport layer 5, a blue light-emitting layer 6B, and a second charge transport layer 7, an upper pixel electrode 9, and a common electrode 11. In the display device 1 shown in Figure 2, an example will be described in which the first charge transport layer 5 and the second charge transport layer 7 are each provided as a common layer (one layer) for the red pixel RSP, the green pixel GSP, and the blue pixel BSP, respectively. However, this is not limited to this, and at least one of the first charge transport layer 5 and the second charge transport layer 7 may be provided for each pixel of each color, similar to the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B.

[0017] The substrate 2 includes a thin film transistor layer including a plurality of transistors (not shown). Among the plurality of transistors included in the substrate 2, a drain electrode of a transistor that drives a red light emitting element 30R included in a red pixel RSP is electrically connected to the lower pixel electrode 3 provided in the red pixel RSP, a drain electrode of a transistor that drives a green light emitting element 30G included in a green pixel GSP is electrically connected to the lower pixel electrode 3 provided in the green pixel GSP, and a drain electrode of a transistor that drives a blue light emitting element 30B included in a blue pixel BSP is electrically connected to the lower pixel electrode 3 provided in the blue pixel BSP.

[0018] In this embodiment, the red light-emitting element 30R, green light-emitting element 30G, and blue light-emitting element 30B shown in FIG. 2 each have a top-emission forward stack structure. However, this is not limiting and the elements may have a top-emission inverted stack structure, a bottom-emission forward stack structure, or a bottom-emission inverted stack structure. The red light-emitting element 30R, green light-emitting element 30G, and blue light-emitting element 30B each have a forward stack structure in which the upper pixel electrode 9 (cathode) and the common electrode 11 are arranged above the lower pixel electrode 3 (anode). In this case, to achieve a top-emission structure, the lower pixel electrode 3 (anode) may be formed from an electrode material that reflects visible light, and the upper pixel electrode 9 (cathode) and the common electrode 11 may be formed from an electrode material that transmits visible light. Alternatively, to achieve a bottom-emission structure, the lower pixel electrode 3 (anode) may be formed from an electrode material that transmits visible light, and at least one of the upper pixel electrode 9 (cathode) and the common electrode 11 may be formed from an electrode material that reflects visible light. On the other hand, in the case of an inverted stack structure in which the upper pixel electrode 9, which is an anode, and the common electrode 11 are arranged as layers above the lower pixel electrode 3, which is a cathode, in order to make it a top emission type, the lower pixel electrode 3, which is a cathode, can be formed from an electrode material that reflects visible light, and the upper pixel electrode 9, which is an anode, and the common electrode 11 can be formed from an electrode material that transmits visible light, and in order to make it a bottom emission type, the lower pixel electrode 3, which is a cathode, can be formed from an electrode material that transmits visible light, and at least one of the upper pixel electrode 9, which is an anode, and the common electrode 11 can be formed from an electrode material that reflects visible light.

[0019] The electrode material that reflects visible light is not particularly limited as long as it can reflect visible light and has electrical conductivity. Examples of the electrode material that reflects visible light include metal materials such as Al, Mg, Li, and Ag, alloys of the metal materials, laminates of the metal materials and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), and laminates of the alloys and the transparent metal oxides.

[0020] On the other hand, the electrode material that transmits visible light is not particularly limited as long as it can transmit visible light and has conductivity, and examples thereof include transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), thin films made of metal materials such as Al and Ag, and nanowires made of metal materials such as Al and Ag.

[0021] In this embodiment, as shown in FIG. 2 , a case where the display device 1 includes a bank 4 including a portion formed thicker than the lower pixel electrode 3 is described as an example. However, this is not limited to this. In the following embodiment 6, a display device 1e may not include a bank 4, as shown in FIG. 9 . As described above, the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B shown in FIG. 2 each have a top-emission sequential stack structure. Therefore, the island-shaped lower pixel electrodes 3 provided for each pixel RSP, GSP, and BSP of each color on the substrate 2 can be formed of an electrode material that serves as an anode and reflects visible light. The bank 4 is formed to fill the ends of the island-shaped lower pixel electrodes 3 and the regions between adjacent island-shaped lower pixel electrodes 3. Furthermore, as shown in FIG. 2 , the central portion 3c of the lower pixel electrode 3 and the portion of the peripheral portion 3p surrounding the central portion 3c of the lower pixel electrode 3 other than the end overlap with the opening provided in the bank 4 in a plan view. The bank 4 can be formed, for example, by applying an organic material such as polyimide or acrylic and then patterning it using a photolithography method. In this embodiment, the bank 4 is patterned so that each of the opposing side surfaces has an inclined surface with a forward taper angle.

[0022] As shown in Figure 2, the island-shaped upper pixel electrodes 9 provided for each color pixel RSP, GSP, and BSP overlap with the central portion 3c of the lower pixel electrode 3 in a planar view but do not overlap with the peripheral portion 3p of the lower pixel electrode 3 in a planar view, and since the red light-emitting element 30R, green light-emitting element 30G, and blue light-emitting element 30B each have a top-emission type forward stack structure, they can be formed from an electrode material that is a cathode and transmits visible light.

[0023] As shown in FIG. 2, the common electrode 11 electrically connected to each of the plurality of upper pixel electrodes 9 can be formed from an electrode material that transmits visible light, since the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B each have a top-emission type stacked structure.

[0024] As shown in Figure 2, a functional layer 8G including an island-shaped green light-emitting layer 6G that is larger than the upper pixel electrode 9 in a planar view is provided between the lower pixel electrode 3 and upper pixel electrode 9 provided in the green pixel GSP of the display device 1, a functional layer 8R including an island-shaped red light-emitting layer 6R that is larger than the upper pixel electrode 9 in a planar view is provided between the lower pixel electrode 3 and upper pixel electrode 9 provided in the red pixel RSP of the display device 1, and a functional layer 8B including an island-shaped blue light-emitting layer 6B that is larger than the upper pixel electrode 9 in a planar view is provided between the lower pixel electrode 3 and upper pixel electrode 9 provided in the blue pixel BSP of the display device 1. In this embodiment, the functional layer 8R including the red light-emitting layer 6R is a laminate in which a first charge transport layer 5, an island-shaped red light-emitting layer 6R, and a second charge transport layer 7 are stacked in this order from the lower pixel electrode 3 side; the functional layer 8G including the green light-emitting layer 6G is a laminate in which a first charge transport layer 5, an island-shaped green light-emitting layer 6G, and a second charge transport layer 7 are stacked in this order from the lower pixel electrode 3 side; and the functional layer 8B including the blue light-emitting layer 6B is a laminate in which a first charge transport layer 5, an island-shaped blue light-emitting layer 6B, and a second charge transport layer 7 are stacked in this order from the lower pixel electrode 3 side. However, this is not limited to this, and at least one of the first charge transport layer 5 and the second charge transport layer 7 may be omitted as appropriate in each of the functional layers 8R, 8G, and 8B. In this embodiment, the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B are each formed in an island shape, but the present invention is not limited thereto. For example, the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B may each be a stripe-shaped light-emitting layer provided across multiple pixels of the corresponding color. Furthermore, for example, if the display device is a color conversion (CCM (Color Conversion Material)) display device, for example, active matrix driving can be used to cause only a predetermined region of one light-emitting layer to emit light, and a color conversion layer that converts blue light from the predetermined region of the light-emitting layer to red light or green light is separately provided. Therefore, the light-emitting layer may be, for example, a single light-emitting layer that emits a single color (e.g., blue) formed over the entire display area.

[0025] In addition, when the red light-emitting element, the green light-emitting element, and the blue light-emitting element each have a top-emission type inverted stack structure, the functional layer including the red light-emitting layer may be a laminate in which the second charge transport layer 7, the island-shaped red light-emitting layer 6R, and the first charge transport layer 5 are stacked in this order from the lower pixel electrode 3 side, the functional layer including the green light-emitting layer may be a laminate in which the second charge transport layer 7, the island-shaped green light-emitting layer 6G, and the first charge transport layer 5 are stacked in this order from the lower pixel electrode 3 side, and the functional layer including the blue light-emitting layer may be a laminate in which the second charge transport layer 7, the island-shaped blue light-emitting layer 6B, and the first charge transport layer 5 are stacked in this order from the lower pixel electrode 3 side.

[0026] As described above, the display device 1 includes the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B having a forward stack structure, and therefore each of the plurality of lower pixel electrodes 3 is an anode, each of the plurality of upper pixel electrodes 9 is a cathode, the first charge transport layer 5 includes at least one of a hole injection layer and a hole transport layer, and the second charge transport layer 7 includes at least one of an electron injection layer and an electron transport layer. However, when the display device includes the red light-emitting element, the green light-emitting element, and the blue light-emitting element having a reverse stack structure, each of the plurality of lower pixel electrodes 3 is a cathode, each of the plurality of upper pixel electrodes 9 is an anode, the first charge transport layer 5 includes at least one of an electron injection layer and an electron transport layer, and the second charge transport layer 7 includes at least one of a hole injection layer and a hole transport layer.

[0027] The material used for the hole injection layer (HIL) is not particularly limited as long as it is a hole injection material that can stabilize the injection of holes into the light emitting layer, and for example, a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT:PSS) can be used.

[0028] Examples of materials used for the hole transport layer (HTL) include organic materials such as poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] (TFB), N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine (poly-TPD), and polyvinylcarbazole (PVK), and nanoparticles having hole transport properties such as NiO particles.

[0029] The material used for the electron transport layer (ETL) may be, for example, an organic material such as 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), or nanoparticles having electron transport properties such as ZnO particles or particles of an oxide containing Zn and Mg.

[0030] The material used for the electron injection layer (EIL) is not particularly limited as long as it is an electron-injecting material that can stabilize the injection of electrons into the light-emitting layer. For example, alkali metals or alkaline earth metals such as aluminum, strontium, calcium, lithium, cesium, magnesium oxide, aluminum oxide, strontium oxide, lithium oxide, lithium fluoride, magnesium fluoride, strontium fluoride, calcium fluoride, barium fluoride, cesium fluoride, polymethyl methacrylate polystyrene sodium sulfonate, oxides of alkali metals or alkaline earth metals, fluorides of alkali metals or alkaline earth metals, organic complexes of alkali metals, etc. may be used.

[0031] In this embodiment, the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B are described as being QLEDs (quantum dot light-emitting diodes) as an example, but this is not limited to this, and the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B may be OLEDs (organic light-emitting diodes), or further, some of the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B may be QLEDs, and the remaining parts of the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B may be OLEDs.

[0032] When the red light-emitting element 30R, the green light-emitting element 30G, and the blue light-emitting element 30B are QLEDs, the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B provided in each light-emitting element of each color contain quantum dots (QDs). The surface of each quantum dot (QD) may be provided with a ligand (e.g., a halogen ligand or an organic ligand) to prevent aggregation of the quantum dots (QDs). Furthermore, in addition to the quantum dots (QDs) and ligands, each of the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B may contain a matrix made of an inorganic material (e.g., metal sulfide or silicon oxide) or an organic material. The quantum dots (QDs) may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously changing core / shell ratio. The core part can be made of, for example, Si, C, etc. in the case of a unicomponent system, CdSe, CdS, CdTe, InP, GaP, InN, ZnSe, ZnS, ZnTe, etc. in the case of a ternary system, CdSeTe, GaInP, ZnSeTe, etc., and can be made of, for example, AIGS, etc. The shell part can be made of, for example, CdS, CdTe, CdSe, ZnS, ZnSe, ZnTe, etc. in the case of a ternary system, CdSSe, CdTeSe, CdSTe, ZnSSe, ZnSTe, ZnTeSe, AIP, etc. in the case of a ternary system.

[0033] On the other hand, when the red light emitting element 30R, the green light emitting element 30G, and the blue light emitting element 30B are OLEDs, the red light emitting layer 6R, the green light emitting layer 6G, and the blue light emitting layer 6B included in the light emitting elements of each color contain an organic light emitting material, which can be formed by, for example, a vapor deposition method.

[0034] 2 , for example, in a green pixel GSP of the display device 1, a functional layer 8G including an island-shaped green light-emitting layer 6G that is larger than the upper pixel electrode 9 in a planar view is provided between the lower pixel electrode 3 and the upper pixel electrode 9. In this embodiment, the functional layer 8G including the green light-emitting layer 6G includes, in addition to the island-shaped green light-emitting layer 6G that is larger than the upper pixel electrode 9 in a planar view, a first charge transport layer 5 that is larger than the upper pixel electrode 9 in a planar view, and a second charge transport layer 7 that is larger than the upper pixel electrode 9 in a planar view. The functional layer 8G including the green light-emitting layer 6G includes a first portion 8G1 (a portion surrounded by a dotted line in FIG. 2 ) that includes a part of the island-shaped green light-emitting layer 6G and overlaps with a central portion 3c of the lower pixel electrode 3 in a planar view, and a second portion 8G2 that includes another part of the island-shaped green light-emitting layer 6G and overlaps with a portion 3pc of a peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer 8G in a planar view. In this embodiment, the first portion 8G1 and the second portion 8G2 of the functional layer 8G including the green light-emitting layer 6G are each a laminate of the first charge transport layer 5, the green light-emitting layer 6G, and the second charge transport layer 7, but are not limited to this. The average film thickness of the first portion 8G1 of the functional layer 8G is different from the average film thickness of the second portion 8G2 of the functional layer 8G. Specifically, in this embodiment, the average film thickness of the second portion 8G2 of the functional layer 8G is thicker than the average film thickness of the first portion 8G1 of the functional layer 8G. This is not a limitation, and it is sufficient that the average film thicknesses of the first portion 8G1 of the functional layer 8G and the second portion 8G2 of the functional layer 8G are different. In a sixth embodiment described below, the average film thickness of the first portion 8G1 of the functional layer 8G may be thicker than the average film thickness of the second portion 8G2 of the functional layer 8G, as in the display device 1e shown in FIG. Here, the green pixel GSP of the display device 1 has been described as an example, but in this embodiment, in each of the red pixel RSP and blue pixel BSP of the display device 1, as in the green pixel GSP, the average film thickness of the second portion of the functional layer 8R is thicker than the average film thickness of the first portion of the functional layer 8R, and the average film thickness of the second portion of the functional layer 8B is thicker than the average film thickness of the first portion of the functional layer 8B.As shown in FIGS. 2 and 3 , the insulating layer 10 covers the ends of the upper pixel electrodes 9 and the spaces between the ends, and has openings 10k that do not cover a portion of the upper surface 9u opposite the lower surface 9d, on which the red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B of each upper pixel electrode 9 are located. The common electrode 11 is electrically connected to each of the upper pixel electrodes 9 through each of the openings 10k in the insulating layer 10. The thickness of the insulating layer 10 is not particularly limited as long as it can ensure insulation, but is preferably 300 nm or more and 3000 nm or less, taking into account insulation and film-forming properties. Furthermore, the insulating layer 10 is not particularly limited as long as it can ensure insulation, but preferably contains a photosensitive resin that can be patterned by exposure and development processes. Forming the insulating layer 10 using a photosensitive resin allows for high-resolution patterning with high productivity. As the photosensitive resin, a positive insulating photosensitive resin may be used, a negative insulating photosensitive resin may be used, or a positive insulating photosensitive resin that transmits visible light may be used.

[0035] The first portion 8G1 of the functional layer 8G, the first portion of the functional layer 8R, and the first portion of the functional layer 8B are portions where the lower pixel electrode 3 and the upper pixel electrode 9 overlap in a planar view, i.e., light-emitting regions. In this embodiment, each functional layer is formed with an optimal thickness taking into account the luminous efficiency of the light-emitting region. The second portion 8G2 of the functional layer 8G, the second portion of the functional layer 8R, and the second portion of the functional layer 8B are portions where the lower pixel electrode 3 and the upper pixel electrode 9 do not overlap in a planar view. In this embodiment, the average thickness of the second portion 8G2 of the functional layer 8G is thicker than the average thickness of the first portion 8G1 of the functional layer 8G, the average thickness of the second portion of the functional layer 8R is thicker than the average thickness of the first portion of the functional layer 8R, and the average thickness of the second portion of the functional layer 8B is thicker than the average thickness of the first portion of the functional layer 8B. The average thickness of the second portion is different from the optimal thickness. When a current flows through the second portion, the luminous efficiency of the second portion is lower than that of the first portion, thereby reducing the average luminous efficiency of the entire pixel of the corresponding color. According to the display device 1, almost no current flows through the second portion because the lower pixel electrode 3 and the upper pixel electrode 9 do not overlap in a planar view. This suppresses current flowing through the second portion, which has a film thickness different from the optimal film thickness considering light-emission efficiency, i.e., the region with low light-emission efficiency. This allows for high light-emission efficiency and a long lifespan for the display device 1. Furthermore, because the insulating layer 10 is located above the upper pixel electrode 9, misalignment of the insulating layer 10 does not result in misalignment of the light-emitting region. Therefore, even if the insulating layer 10 is formed wider than the distance between adjacent pixels, the light-emitting region does not become narrower. Therefore, high efficiency can be achieved without excessively narrowing the area of ​​the light-emitting region, even in a high-resolution device in which the distance between adjacent pixels is short.

[0036] 2 , the red pixel RSP, green pixel GSP, and blue pixel BSP of the display device 1 each include a first region RE1 and a second region RE2. For example, the first region RE1 of the green pixel GSP is a region where, in a plan view, the central portion 3c of the lower pixel electrode 3, the first portion 8G1 of the functional layer 8G, and the upper pixel electrode 9 overlap, and the second region RE2 of the green pixel GSP is a region where, in a plan view, the upper pixel electrode 9 is not formed, among the regions where, in a plan view, the portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer 8G, the functional layer 8G, and the insulating layer 10 overlap. Although not shown, the red pixel RSP and blue pixel BSP of the display device 1 each include a first region RE1 and a second region RE2 similar to the above-mentioned green pixel GSP. According to the display device 1, the first region RE1 including the first part of the functional layer having an optimized film thickness so as to have a higher luminous efficiency than the second part of the functional layer is used as a light-emitting region, and almost no current flows in the second region RE2 including the second part of the functional layer having a lower luminous efficiency than the first part of the functional layer, thereby realizing a display device 1 with high luminous efficiency.

[0037] 2, each of the red pixel RSP, green pixel GSP, and blue pixel BSP of the display device 1 includes a third region RE3 and a fourth region RE4. For example, the second region RE2 of the green pixel GSP is composed of the third region RE3 and the fourth region RE4, the third region RE3 is closer to the first region RE1 than the fourth region RE4, the film thickness of the functional layer 8G in the third region RE3 is the same as the film thickness of the functional layer 8G in the first region RE1, and the film thickness of the functional layer 8G in the fourth region RE4 is different from the film thickness of the functional layer 8G in the first region RE1. 2 , the shortest distance between the end of the first region RE1 in contact with the third region RE3 and the end of the fourth region RE4 in contact with the third region RE3 is smaller than the shortest distance between the upper surface 3u of the lower pixel electrode 3 on the green light-emitting layer 6G side and the lower surface 9d of the upper pixel electrode 9 on the green light-emitting layer 6G side in the green pixel GSP, but the shortest distance between the end of the first region RE1 in contact with the third region RE3 and the end of the fourth region RE4 in contact with the third region RE3 is preferably larger than the shortest distance between the upper surface 3u of the lower pixel electrode 3 on the green light-emitting layer 6G side and the lower surface 9d of the upper pixel electrode 9 on the green light-emitting layer 6G side in the green pixel GSP. Although not shown, the red pixel RSP and the blue pixel BSP of the display device 1 also each include the third region RE3 and the fourth region RE4 similar to the above-mentioned green pixel GSP. Even if the third region RE3 is provided as in the display device 1 of this embodiment shown in Figure 2, the current flowing in the fourth region RE4 can be suppressed and the average luminous efficiency of the entire pixel of the corresponding color can be improved, but the current flowing in the fourth region RE4 can be further suppressed by making the shortest distance between the end of the first region RE1 that contacts the third region RE3 and the end of the fourth region RE4 that contacts the third region RE3 larger than the shortest distance between the upper surface 3u of the lower pixel electrode 3 and the lower surface 9d of the upper pixel electrode 9.

[0038] 2 , for example, the functional layer 8G provided in the green pixel GSP of the display device 1 includes a first charge transport layer 5, which is a common layer provided between the lower pixel electrode 3 and the green light-emitting layer 6G, the green light-emitting layer 6G, and a second charge transport layer, which is a common layer provided between the upper pixel electrode 9 and the green light-emitting layer 6G. In at least one of the first charge transport layer 5, the green light-emitting layer 6G, and the second charge transport layer 7, the average film thickness of the first region RE1 is different from the average film thickness of the second region RE2, and the average film thickness of the first portion 8G1 of the functional layer 8G is different from the average film thickness of the second portion 8G2 of the functional layer 8G. Specifically, in this embodiment, in the laminate of the first charge transport layer 5, the green light-emitting layer 6G, and the second charge transport layer 7, the average film thickness of the second region RE2 is thicker than the average film thickness of the first region RE1, and the average film thickness of the second portion 8G2 of the functional layer 8G is thicker than the average film thickness of the first portion 8G1 of the functional layer 8G. Although not shown, the functional layer 8R provided in the red pixel RSP of the display device 1 is similar to the functional layer 8G, and in at least one of the first charge transport layer 5, the red light-emitting layer 6R, and the second charge transport layer 7, the average film thickness of the first region RE1 is different from the average film thickness of the second region RE2, and the average film thickness of the first portion of the functional layer 8R is different from the average film thickness of the second portion of the functional layer 8R. Specifically, in this embodiment, in the laminate of the first charge transport layer 5, the red light-emitting layer 6R, and the second charge transport layer 7, the average film thickness of the second region RE2 is thicker than the average film thickness of the first region RE1, and the average film thickness of the second portion of the functional layer 8R is thicker than the average film thickness of the first portion of the functional layer 8R. Although not shown, the functional layer 8B provided in the blue pixel BSP of the display device 1 is similar to the functional layer 8G, and in at least one of the first charge transport layer 5, the blue light-emitting layer 6B, and the second charge transport layer 7, the average film thickness of the first region RE1 is different from the average film thickness of the second region RE2, and the average film thickness of the first portion of the functional layer 8B is different from the average film thickness of the second portion of the functional layer 8B. Specifically, in this embodiment, in the laminate of the first charge transport layer 5, the blue light-emitting layer 6B, and the second charge transport layer 7, the average film thickness of the second region RE2 is thicker than the average film thickness of the first region RE1, and the average film thickness of the second portion of the functional layer 8B is thicker than the average film thickness of the first portion of the functional layer 8R.

[0039] 2 , in this embodiment, the red pixel RSP of the display device 1 is provided with only the red light-emitting layer 6R out of the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B, the green pixel GSP of the display device 1 is provided with only the green light-emitting layer 6G out of the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B, and the blue pixel BSP of the display device 1 is provided with only the blue light-emitting layer 6B out of the red light-emitting layer 6R, the green light-emitting layer 6G, and the blue light-emitting layer 6B, respectively. For example, in the green pixel GSP of the display device 1, in a region overlapping with a portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer 8G in a planar view, the green light-emitting layer 6G and the red light-emitting layer 6R may be stacked, or the green light-emitting layer 6G and the blue light-emitting layer 6B may be stacked. According to this configuration, by stacking multiple types of light-emitting layers in areas other than the first region RE1, which includes the first portion of the functional layer having an optimized film thickness, it is possible to improve insulation properties, thereby achieving high light-emitting efficiency and a long lifespan for the display device.

[0040] Although not shown, a sealing layer for preventing foreign substances such as water and oxygen from penetrating into the red light emitting element 30R, the green light emitting element 30G, and the blue light emitting element 30B is preferably provided on the common electrode 11 provided in the display device 1. The sealing layer is a light-transmitting film, and may be formed, for example, by a laminated film of a first inorganic sealing film, an organic film, and a second inorganic sealing film.

[0041] FIG. 4 is a diagram for explaining a method for manufacturing the display device 1 of the first embodiment.

[0042] As shown in FIG. 4 , the manufacturing method of the display device 1 includes a lower pixel electrode forming step (S1) of forming an island-shaped lower pixel electrode 3, an upper pixel electrode forming step (S3) which is a step performed after the lower pixel electrode forming step (S1) and forms an island-shaped upper pixel electrode 9 which overlaps with a central portion 3 c of the lower pixel electrode 3 in a planar view but does not overlap with a peripheral portion 3 p surrounding the central portion 3 c of the lower pixel electrode 3 in a planar view, and a step performed between the lower pixel electrode forming step (S1) and the upper pixel electrode forming step (S3) of forming a red light-emitting layer 6R, a green light-emitting layer 6G, and a blue light-emitting layer 6H which are larger than the upper pixel electrode 9 in a planar view. The method includes a functional layer formation process (S2) for forming a functional layer, which includes a light-emitting layer formation process for forming each of the color light-emitting layers 6B; an insulating layer formation process (S4), which is a process carried out after the upper pixel electrode formation process (S3), for forming an insulating layer 10 over the entire surface to cover the upper pixel electrode 9; an opening formation process (S5), which is a process carried out after the insulating layer formation process (S4), for forming an opening 10k in the insulating layer 10 in a part of the upper surface 9u of the upper pixel electrode 9; and a common electrode formation process (S6), which is a process carried out after the opening formation process (S5), for forming a common electrode 11 electrically connected to the upper pixel electrode 9 via the opening 10k in the insulating layer 10. In the functional layer formation step (S2), as shown in FIG. 2, a functional layer 8G is formed, including a first portion 8G1 that includes a portion of the island-shaped green light-emitting layer 6G and overlaps the central portion 3c of the lower pixel electrode 3 in a planar view, and a second portion 8G2 that includes another portion of the island-shaped green light-emitting layer 6G and overlaps the portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer 8G in a planar view, and has an average thickness different from that of the first portion 8G1. In this embodiment, a functional layer 8G in which the average thickness of the second portion 8G2 of the functional layer 8G is thicker than that of the first portion 8G1 of the functional layer 8G, a functional layer 8R in which the average thickness of the second portion of the functional layer 8R is thicker than that of the first portion of the functional layer 8R, and a functional layer 8B in which the average thickness of the second portion of the functional layer 8B is thicker than that of the first portion of the functional layer 8B are formed. However, this is not limiting. The above-described manufacturing method for the display device 1 can achieve high luminous efficiency, long life, and high definition for the display device 1.

[0043] In this embodiment, due to the influence of the slope having a forward taper angle of the bank 4, a functional layer 8G is formed in which the average thickness of the second portion 8G2 of the functional layer 8G is thicker than the average thickness of the first portion 8G1 of the functional layer 8G, a functional layer 8R is formed in which the average thickness of the second portion of the functional layer 8R is thicker than the average thickness of the first portion of the functional layer 8R, and a functional layer 8B is formed in which the average thickness of the second portion of the functional layer 8B is thicker than the average thickness of the first portion of the functional layer 8B. However, this is not limited to this, and for example, even in a display device that does not have a bank 4, when the functional layer is patterned using a lift-off method using a resist film, due to the influence of the slope of the opening in the resist film, a functional layer 8G is formed in which the average thickness of the second portion 8G2 of the functional layer 8G is thicker than the average thickness of the first portion 8G1 of the functional layer 8G, a functional layer 8R is formed in which the average thickness of the second portion of the functional layer 8R is thicker than the average thickness of the first portion of the functional layer 8R, and a functional layer 8B is formed in which the average thickness of the second portion of the functional layer 8G2 is thicker than the average thickness of the first portion of the functional layer 8G, a functional layer 8R is formed in which the average thickness of the second portion of the functional layer 8R is thicker than the average thickness of the first portion of the functional layer 8R, and a functional layer 8B is formed in which the average thickness of the second portion of the functional layer 8B is thicker than the average thickness of the first portion of the functional layer 8B. Furthermore, even when the functional layer is not patterned, due to the influence of the uneven shape of the deposition surface, such as the end of the lower pixel electrode and the slope of the bank, a functional layer 8G is formed in which the average thickness of the second portion 8G2 of the functional layer 8G is different from the average thickness of the first portion 8G1 of the functional layer 8G, a functional layer 8R is formed in which the average thickness of the second portion of the functional layer 8R is different from the average thickness of the first portion of the functional layer 8R, and a functional layer 8B is formed in which the average thickness of the second portion of the functional layer 8B is different from the average thickness of the first portion of the functional layer 8B.

[0044] Second Embodiment Next, a second embodiment of the present disclosure will be described with reference to Fig. 5. Fig. 5 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device 1a of the second embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0045] In the display device 1a shown in FIG. 5 , the common electrode 11 is provided larger than the upper pixel electrode 9 in a planar view in the green pixel GSP, for example. Although not shown, the common electrode 11 is also provided larger than the upper pixel electrode 9 in a planar view in each of the red and blue pixels. The common electrode 11 and the upper pixel electrode 9 are each an electrode that transmits visible light, and the lower pixel electrode 3 is an electrode that reflects visible light. At least in a region ORE where the common electrode 11 and the upper pixel electrode 9 overlap in a planar view, a light scattering layer 21 is provided as a layer above the upper pixel electrode 9. In this embodiment, a case where the light scattering layer 21 is formed over the entire surface of the common electrode 11, which is above the upper pixel electrode 9, is described as an example. However, the present invention is not limited to this. The light scattering layer 21 may be provided above the upper pixel electrode 9 or as part of the upper pixel electrode 9, at least in the region ORE where the common electrode 11 and the upper pixel electrode 9 overlap in a planar view. When the light-scattering layer 21 is provided above the upper pixel electrode 9, the light-scattering layer 21 may be formed using a material that scatters visible light. The upper pixel electrode 9 may also serve as the light-scattering layer 21. In this case, the upper pixel electrode 9 may be formed of a light-scattering material, for example, the upper pixel electrode 9 may be formed of silver nanowires. In the display device 1a shown in FIG. 5 , in the portion where the lower pixel electrode 3 and the upper pixel electrode 9 overlap in a planar view, i.e., in the light-emitting region, the film thickness of the portion where the insulating layer 10 is present is thicker than the film thickness of the portion where the insulating layer 10 is not present. Since the distance from the green light-emitting layer 6G to the common electrode 11 differs between the portion where the insulating layer 10 is present and the portion where the insulating layer 10 is not present, the degree of the resonance effect differs, and efficiency decreases in one of the regions. Therefore, in the display device 1a of this embodiment, a light scattering layer 21 is provided that can convert light from the green light emitting layer 6G into scattered light L1, so that the light scattering layer 21 causes the coherence of the light from the green light emitting layer 6G to be lost, and by aligning both the parts in the light emitting region where the insulating layer 10 is present and the parts where the insulating layer 10 is not present in a state where there is no resonance effect, the overall efficiency can be improved.

[0046] Third Embodiment Next, a third embodiment of the present disclosure will be described with reference to Fig. 6. Fig. 6 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device 1b of the third embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0047] In the display device 1b shown in FIG. 6 , the common electrode 11 is provided larger than the upper pixel electrode 9 in a planar view in, for example, the green pixel GSP. Although not shown, the common electrode 11 is also provided larger than the upper pixel electrode 9 in a planar view in each of the red pixel and the blue pixel. The common electrode 11 and the upper pixel electrode 9 are each an electrode that transmits visible light, and the lower pixel electrode 3 is an electrode that reflects visible light. At least in a region ORE where the common electrode 11 and the upper pixel electrode 9 overlap in a planar view, a planarization film 22 is provided as an upper layer than the common electrode 11. In this embodiment, a case where the planarization film 22 is formed over the entire surface of the common electrode 11 will be described as an example, but this is not limiting, and the planarization film 22 may be provided as an upper layer than the common electrode 11 at least in a region ORE where the common electrode 11 and the upper pixel electrode 9 overlap in a planar view. The planarization film 22 may be made of any material that transmits visible light, including, for example, a coatable organic material such as polyimide or acrylic. Considering the need to flatten the step formed by the opening 10k in the insulating layer 10, the planarization film 22 is preferably formed to a thickness of 1 μm or greater. Furthermore, the planarization film 22 is preferably made of a material with a refractive index of 1.5 or greater and 2.5 or less. In the display device 1b shown in FIG. 6 , the planarization film 22 is formed across the portion where the lower pixel electrode 3 and the upper pixel electrode 9 overlap in a planar view, i.e., the light-emitting region, spanning both the portion where the insulating layer 10 is present and the portion where the insulating layer 10 is absent. The thickness of the planarization film 22 is thicker in the portion where the insulating layer 10 is absent than in the portion where the insulating layer 10 is present. In the display device 1b shown in Figure 6, the planarization film 22 can shorten the distance from the green light-emitting layer 6G to the light-emitting surface of the planarization film 22 in the part of the light-emitting region where the insulating layer 10 is present and in the part where the insulating layer 10 is not present, and by shortening the resonance effects of both the part of the light-emitting region where the insulating layer 10 is present and the part where the insulating layer 10 is not present, the overall efficiency can be improved.

[0048] Fourth Embodiment Next, a fourth embodiment of the present disclosure will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device 1c of the fourth embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0049] In the green light-emitting element 30Ga included in the display device 1c shown in FIG. 7 , the common electrode 11 is larger than the upper pixel electrode 9a in the green pixel GSP in a planar view. Although not shown, the common electrode 11 is also larger than the upper pixel electrode 9a in the red and blue light-emitting elements included in the display device 1c in a planar view in both the red and blue pixels. The common electrode 11 is an electrode that transmits visible light, the upper pixel electrode 9a is a metal thin-film electrode formed with a thickness that transmits visible light, and the lower pixel electrode 3 is an electrode that reflects visible light. In this embodiment, the upper pixel electrode 9a is formed, for example, of Ag with a thickness of 20 nm. However, this is not limited thereto, and the common electrode 11 may be formed, for example, of MgAg with a thickness of 20 nm. The common electrode 11 may be formed, for example, of a transparent metal oxide (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.). According to the display device 1c, in the portion where the lower pixel electrode 3 and the upper pixel electrode 9a overlap in a planar view, i.e., in the light-emitting region, the upper pixel electrode 9a forms the main reflection surface, and therefore the difference in the structure of the layers above the upper pixel electrode 9a, in this embodiment, the difference in the presence or absence of the insulating layer 10, hardly changes the resonance effect, and the resonator length can be made uniform in both the portion with the insulating layer 10 and the portion without the insulating layer 10 in the light-emitting region, so that a strong resonance effect can be utilized and high brightness can be achieved in the display device 1c.

[0050] Fifth Embodiment Next, a fifth embodiment of the present disclosure will be described with reference to Fig. 8. Fig. 8 is a cross-sectional view showing a schematic configuration of a display region of a display device 1d of the fifth embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0051] The display device 1d shown in FIG. 8 includes a bank 4 having opposing side surfaces each formed as a slope having a forward taper angle and including a portion formed thicker than the lower pixel electrode 3. The lower pixel electrode 3 is an electrode that reflects visible light, and at least a portion of a peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer is provided on the slope of the bank 4. The display device 1d shown in FIG. 8 illustrates a case in which the peripheral portion 3p of the lower pixel electrode 3 and the portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer coincide with each other. The lower pixel electrode 3 may be, for example, a single layer formed of Ag or the like, or a laminate formed of a transparent metal oxide and Ag. In the green light-emitting element 30Gb included in the display device 1d, a portion of light from the green light-emitting layer 6G is reflected by the peripheral portion 3p of the lower pixel electrode 3 that is provided on the slope having a forward taper angle of the bank 4, and can be output as light L2. In each of the red light-emitting element 30Rb and the blue light-emitting element 30Bb provided in the display device 1d, a portion of light from the light-emitting layer can be reflected by a peripheral portion 3p of the lower pixel electrode 3 provided on the sloped surface having a forward taper angle provided in the bank 4, and can be output as output light L2. The peripheral portion 3p of the lower pixel electrode 3 provided on the sloped surface having a forward taper angle provided in the bank 4 is also referred to as a light extraction structure. The display device 1d having the light extraction structure can achieve higher brightness even when driven with the same current value compared to a display device without a light extraction structure, thereby realizing a longer lifespan.

[0052] Sixth Embodiment Next, a sixth embodiment of the present disclosure will be described with reference to Fig. 9. Fig. 9 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device 1e of the sixth embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0053] As shown in FIG. 9 , the display device 1e differs from the display devices of the first to fifth embodiments in that it does not include a bank 4. The display device 1e includes a first charge transport layer 5, which is a common layer provided between each of the plurality of lower pixel electrodes 3 and each of the plurality of light-emitting layers (red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B). The first charge transport layer 5 is provided so as to fill the spaces between the plurality of lower pixel electrodes 3. In this embodiment, a case where the lower pixel electrode 3 side of the substrate 2 has a flattened surface is described as an example. However, this is not limited thereto. The lower pixel electrode 3 side of the substrate 2 may not be completely flat and may have an uneven shape due to, for example, the influence of a wiring layer. In such a case, the lower pixel electrodes 3 and the first charge transport layer 5 are formed so as to fill the uneven shape.

[0054] 9 , the display device 1e includes a second charge transport layer 7, which is a common layer provided between each of the plurality of upper pixel electrodes 9 and each of the plurality of light-emitting layers (red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B). The average thickness of the stacked film of the first charge transport layer 5, the light-emitting layer (any of the red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B), and the second charge transport layer 7 provided between a portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer and the insulating layer 10 is smaller than the average thickness of the stacked film of the first charge transport layer 5, the light-emitting layer (any of the red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B), and the second charge transport layer 7 provided between a central portion 3c of the lower pixel electrode 3 and the upper pixel electrode 9. The display device 1e shown in FIG. 9 is a case in which the peripheral portion 3p of the lower pixel electrode 3 and the portion 3pc of the peripheral portion 3p of the lower pixel electrode 3 that contacts the functional layer coincide with each other.

[0055] The display device 1e shown in Figure 9 does not have a bank 4, i.e., it adopts a bankless structure, so that the area where the lower pixel electrode 3 and the upper pixel electrode 9 overlap in a planar view, i.e., the light-emitting area, can be maximized.

[0056] 9 , in the green light-emitting element 30G′ provided in the display device 1e, the average film thickness of the first portion 8G1 of the functional layer 8G is greater than the average film thickness of the second portion 8G2 of the functional layer 8G. Similarly to the green light-emitting element 30G′, the red light-emitting element 30R′ provided in the display device 1e also has the average film thickness of the first portion of the functional layer 8R greater than the average film thickness of the second portion of the functional layer 8R. Similarly to the green light-emitting element 30G′, the blue light-emitting element 30B′ provided in the display device 1e also has the average film thickness of the first portion of the functional layer 8B greater than the average film thickness of the second portion of the functional layer 8B. Therefore, the second portion of the functional layer, which is thinner than the average film thickness of the first portion of the functional layer, can suppress current flowing to regions with low luminous efficiency due to current spreading in the functional layer, thereby achieving high luminous efficiency, long life, and high definition for the display device 1e.

[0057] Seventh Embodiment Next, a seventh embodiment of the present disclosure will be described with reference to Fig. 10. Fig. 10 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device if of the seventh embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0058] In this embodiment, as shown in FIG. 10, an example will be described in which the display device 1f does not have a bank 4, but this is not limited to this, and the display device 1f may also be configured to have a bank 4.

[0059] As shown in FIG. 10 , the insulating layer 10 of the display device 1f has a plurality of openings 10k in a portion of the upper surface 9u opposite to the side where the light-emitting layer (any of the red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B) of each of the upper pixel electrodes 9 is located. That is, a plurality of openings 10k are provided in the insulating layer 10 for each of the red pixel RSP, green pixel GSP, and blue pixel BSP in a cross section of the display device 1f. Therefore, the display device 1f can be provided with a common electrode 11a with many irregularities, i.e., a pleated common electrode 11a, thereby ensuring mechanical robustness. Note that robustness refers to the property of being less susceptible to various external influences.

[0060] Eighth Embodiment Next, an eighth embodiment of the present disclosure will be described with reference to Fig. 11. Fig. 11 is a cross-sectional view showing a schematic configuration of a display area of ​​a display device 1g of the eighth embodiment, which includes a top-emission type light-emitting element having a forward stack structure.

[0061] 11 , for example, a red pixel RSP included in the display device 1g includes a step portion 36 in an underlayer 35. The underlayer 35 includes, for example, a wiring layer 33 and a planarization layer 34 formed to cover the wiring layer 33. In the red pixel RSP, both a region where the wiring layer 33 is formed and a region where the wiring layer 33 is not formed exist, and these two regions cannot be completely planarized by the planarization layer 34, resulting in the step portion 36. As shown in FIG. 11 , in the display device 1g, for example, a plurality of lower pixel electrodes 3 are provided in the red pixel RSP, and the plurality of lower pixel electrodes 3 within the same pixel are electrically connected to each other via a conductive layer 37 provided on the step portion 36. Although not shown, in the green pixel GSP, similar to the red pixel RSP, each of the plurality of lower pixel electrodes 3 within the same pixel is electrically connected to one another via a conductive layer 37 provided on the step portion 36, and in the blue pixel BSP, each of the plurality of lower pixel electrodes 3 within the same pixel is electrically connected to one another via a conductive layer 37 provided on the step portion 36. In the red pixel RSP, a plurality of upper pixel electrodes 9 are provided, and although not shown, in the green pixel GSP, similar to the red pixel RSP, a plurality of upper pixel electrodes 9 are provided, and in the blue pixel BSP, a plurality of upper pixel electrodes 9 are also provided. Each of the plurality of upper pixel electrodes 9 within the same pixel is provided corresponding to each of the plurality of lower pixel electrodes 3 within the same pixel, and a light-emitting layer (any of the red light-emitting layer 6R, green light-emitting layer 6G, and blue light-emitting layer 6B) is provided as a single layer between each of the plurality of upper pixel electrodes 9 within the same pixel and each of the plurality of lower pixel electrodes 3 within the same pixel. In this embodiment, an example will be given in which the first charge transport layer 5 and the second charge transport layer 7 are each provided as a single layer over the entire display area of ​​the display device 1g, but this is not limited to this.

[0062] According to the display device 1g, even if the red pixel RSP, the green pixel GSP, and the blue pixel BSP each include a step portion 36 in the base layer 35, and the lower pixel electrode 3 also includes a step portion 36, the step portion 36 in the lower pixel electrode 3 is a portion where the lower pixel electrode 3 and the upper pixel electrode 9 do not overlap in a planar view, and almost no current flows through it. On the other hand, a plurality of portions where the lower pixel electrode 3 and the upper pixel electrode 9 overlap in a planar view, i.e., light-emitting regions, are provided within the same pixel, and therefore high light-emitting efficiency of the display device 1g can be achieved even if the step portion 36 in the base layer 35 is included and the lower pixel electrode 3 also includes a step portion 36.

[0063] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0064] The present disclosure can be used in a display device and a method for manufacturing a display device.

[0065] DESCRIPTION OF SYMBOLS 1, 1a, 1b, 1c, 1d, 1e, 1f, 1g Display device 2 Substrate 3 Lower pixel electrode 3c Central portion of lower pixel electrode 3p Peripheral portion of lower pixel electrode 3u Upper surface of lower pixel electrode 3pc Portion of peripheral portion of lower pixel electrode in contact with functional layer 4 Bank 5 First charge transport layer 6R Red light-emitting layer (light-emitting layer) 6G Green light-emitting layer (light-emitting layer) 6B Blue light-emitting layer (light-emitting layer) 7 Second charge transport layer 8R Functional layer including red light-emitting layer 8G Functional layer including green light-emitting layer 8B Functional layer including blue light-emitting layer 8G1 First portion of functional layer including green light-emitting layer 8G2 Second portion of functional layer including green light-emitting layer 9, 9a Upper pixel electrode 9u Upper surface of upper pixel electrode 9d Lower surface of upper pixel electrode 10 Insulating layer 10k Opening in insulating layer 11 Common electrode 21 Light-scattering layer 22 Planarization film 30R, 30Rb, 30R' Red light emitting element 30G, 30Ga, 30Gb, 30G' Green light emitting element 30B, 30Bb, 30B' Blue light emitting element 33 Wiring layer 34 Second planarization film 35 Undercoat layer 36 Step portion 37 Conductive layer RE1 First region RE2 Second region RE3 Third region RE4 Fourth region ORE Region where the common electrode and upper pixel electrode overlap in plan view RSP Red pixel (pixel) GSP Green pixel (pixel) BSP Blue pixel (pixel) PIX Display unit DA Display area NDA Frame area

Claims

1. A display device, comprising: a display region including a plurality of pixels; an island-shaped lower pixel electrode provided for each of the plurality of pixels and composed of a central portion and a peripheral portion surrounding the central portion; an island-shaped upper pixel electrode provided for each of the plurality of pixels, overlapping with the central portion of the lower pixel electrode in a plan view and not overlapping with the peripheral portion of the lower pixel electrode in a plan view; a functional layer including a light-emitting layer provided between the lower pixel electrode and the upper pixel electrode for each of the plurality of pixels and larger than the upper pixel electrode in a plan view; an insulating layer covering each end portion and the portion between the plurality of upper pixel electrodes and having an opening that does not cover a part of the upper surface on the side opposite to the side where the light-emitting layer of each of the plurality of upper pixel electrodes is located; and a common electrode electrically connected to each of the plurality of upper pixel electrodes through each of the plurality of openings of the insulating layer, wherein the functional layer includes a first portion including a part of the light-emitting layer and overlapping with the central portion of the lower pixel electrode in a plan view, and a second portion including another part of the light-emitting layer and overlapping with a portion of the peripheral portion of the lower pixel electrode that is in contact with the functional layer in a plan view, and the average film thickness of the first portion is different from the average film thickness of the second portion.

2. The display device according to claim 1, wherein each of the plurality of pixels includes a first region and a second region, the first region is a region where the central portion of the lower pixel electrode, the first portion of the functional layer, and the upper pixel electrode overlap in a plan view, and the second region is a region where the upper pixel electrode is not formed among the regions where a portion of the peripheral portion of the lower pixel electrode that is in contact with the functional layer, the functional layer, and the insulating layer overlap in a plan view.

3. The second region is composed of a third region and a fourth region. The third region is a region closer to the first region than the fourth region. The film thickness of the functional layer in the third region is the same as the film thickness of the functional layer in the first region. The film thickness of the functional layer in the fourth region is different from the film thickness of the functional layer in the first region. The shortest distance between the end of the first region in contact with the third region and the end of the fourth region in contact with the third region is greater than the shortest distance between the upper surface on the light-emitting layer side of the lower pixel electrode and the lower surface on the light-emitting layer side of the upper pixel electrode in each of the plurality of pixels. The display device according to claim 2.

4. The functional layer includes a first charge transport layer, which is a common layer provided between each of the plurality of lower pixel electrodes and each of the plurality of light-emitting layers, and a second charge transport layer, which is a common layer provided between each of the plurality of upper pixel electrodes and each of the plurality of light-emitting layers. In at least one of the first charge transport layer, the light-emitting layer, and the second charge transport layer, the average film thickness of the first region is different from the average film thickness of the second region. The display device according to claim 2 or 3.

5. Each of the plurality of lower pixel electrodes is an anode, each of the plurality of upper pixel electrodes is a cathode, the first charge transport layer includes at least one of a hole injection layer and a hole transport layer, and the second charge transport layer includes at least one of an electron injection layer and an electron transport layer. The display device according to claim 4.

6. Each of the plurality of lower pixel electrodes is a cathode, each of the plurality of upper pixel electrodes is an anode, the first charge transport layer includes at least one of an electron injection layer and an electron transport layer, and the second charge transport layer includes at least one of a hole injection layer and a hole transport layer. The display device according to claim 4.

7. The film thickness of the insulating layer is 300 nm or more and 3000 nm or less. The display device according to any one of claims 1 to 6.

8. The insulating layer contains a photosensitive resin. The display device according to any one of claims 1 to 7.

9. The common electrode is provided larger than the upper pixel electrode in a plan view for each of the plurality of pixels. Each of the common electrode and the upper pixel electrode is an electrode that transmits visible light. The lower pixel electrode is an electrode that reflects visible light. At least in a region where the common electrode and the upper pixel electrode overlap in a plan view, a light scattering layer is provided as an upper layer than the upper pixel electrode or as the upper pixel electrode. The display device according to any one of claims 1 to 8.

10. The common electrode is provided larger than the upper pixel electrode in a plan view for each of the plurality of pixels. Each of the common electrode and the upper pixel electrode is an electrode that transmits visible light. The lower pixel electrode is an electrode that reflects visible light. At least in a region where the common electrode and the upper pixel electrode overlap in a plan view, a planarization film is provided as an upper layer than the common electrode. The display device according to any one of claims 1 to 8.

11. The common electrode is provided larger than the upper pixel electrode in a plan view for each of the plurality of pixels. The common electrode is an electrode that transmits visible light. The upper pixel electrode is a metal thin film electrode formed with a film thickness that transmits visible light. The lower pixel electrode is an electrode that reflects visible light. The display device according to any one of claims 1 to 8.

12. The insulating layer has a plurality of the openings in a part of an upper surface on a side opposite to a side where the light emitting layer of the upper pixel electrode is located for each of the plurality of the upper pixel electrodes. The display device according to any one of claims 1 to 11.

13. A bank including a portion formed thicker than a film thickness of the lower pixel electrode, each of opposite both side surfaces being a slope having a forward taper angle. The lower pixel electrode is an electrode that reflects visible light. At least a part of a portion of the peripheral portion of the lower pixel electrode that contacts the functional layer is provided on the slope of the bank. The display device according to any one of claims 1 to 12.

14. The display device according to any one of claims 1 to 13, comprising a first charge transport layer which is a common layer provided between each of the plurality of lower pixel electrodes and each of the plurality of light-emitting layers, and the first charge transport layer is provided so as to fill between each of the plurality of lower pixel electrodes.

15. The display device according to claim 14, comprising a second charge transport layer which is a common layer provided between each of the plurality of upper pixel electrodes and each of the plurality of light-emitting layers, and an average film thickness of a laminated film of the first charge transport layer, the light-emitting layer, and the second charge transport layer provided between a portion of the peripheral portion of the lower pixel electrode that contacts the functional layer and the insulating layer is smaller than an average film thickness of a laminated film of the first charge transport layer, the light-emitting layer, and the second charge transport layer provided between the central portion of the lower pixel electrode and the upper pixel electrode.

16. The display device according to any one of claims 1 to 15, wherein the plurality of pixels include a first pixel and a second pixel, the first pixel includes a first light-emitting layer as the light-emitting layer, the second pixel includes a second light-emitting layer different from the first light-emitting layer as the light-emitting layer, and the first light-emitting layer and the second light-emitting layer are laminated in a region overlapping a portion of the peripheral portion of the lower pixel electrode that contacts the functional layer in a plan view.

17. The display device according to any one of claims 1 to 16, wherein each of the plurality of pixels includes a step portion of an underlayer, the lower pixel electrodes are provided in plural for each of the plurality of pixels, and each of the plurality of lower pixel electrodes in the same pixel is electrically connected to each other via a conductive layer provided on the step portion, the upper pixel electrodes are provided in plural for each of the plurality of pixels, each of the plurality of upper pixel electrodes in the same pixel is provided corresponding to each of the plurality of lower pixel electrodes in the same pixel, and the light-emitting layer is provided as one layer between each of the plurality of upper pixel electrodes in the same pixel and each of the plurality of lower pixel electrodes in the same pixel.

18. A method of manufacturing a display device, comprising: a lower pixel electrode forming step of forming an island-shaped lower pixel electrode; an upper pixel electrode forming step, which is performed after the lower pixel electrode forming step, of forming an island-shaped upper pixel electrode that overlaps with a central portion of the lower pixel electrode in a plan view and does not overlap with a peripheral portion surrounding the central portion of the lower pixel electrode in a plan view; a functional layer forming step, which is performed between the lower pixel electrode forming step and the upper pixel electrode forming step, of forming a functional layer including a light emitting layer forming step of forming a light emitting layer that is larger than the upper pixel electrode in a plan view between the lower pixel electrode and the upper pixel electrode; an insulating layer forming step, which is performed after the upper pixel electrode forming step, of forming an insulating layer covering the upper pixel electrode over the entire surface; an opening forming step, which is performed after the insulating layer forming step, of forming an opening in a part of an upper surface of the insulating layer on a side opposite to a side where the light emitting layer of the upper pixel electrode is located; and a common electrode forming step, which is performed after the opening forming step, of forming a common electrode electrically connected to the upper pixel electrode through the opening in the insulating layer. In the functional layer forming step, a functional layer is formed including a first portion including a part of the light emitting layer and overlapping with the central portion of the lower pixel electrode in a plan view, and a second portion including another part of the light emitting layer and overlapping with a portion of the peripheral portion of the lower pixel electrode that contacts the functional layer in a plan view and having an average film thickness different from that of the first portion.

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