Light-emitting element, display device, method for producing light-emitting element, and method for producing display device

Abstract

A red light-emitting element (20R) includes a lower electrode (6), an upper electrode (12) provided above the lower electrode (6), and a red light-emitting layer (RE) provided between the lower electrode (6) and the upper electrode (12). A first laminate (8) in which a first layer (CP1) containing a first conjugated polymer, a first ion layer (IL1), and a second layer (CP1') containing a second conjugated polymer are laminated in the stated order from the lower-electrode (6) side is provided between the lower electrode (6) and the red light-emitting layer (RE). The first conjugated polymer includes a first side chain extending into the first ion layer (IL1). The second conjugated polymer includes a second side chain extending into the first ion layer (IL1).

Description

Light-emitting element, display device, method for manufacturing light-emitting element, and method for manufacturing display device

[0001] The present disclosure relates to a light-emitting element, a display device, a method for manufacturing a light-emitting element, 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 an organic light-emitting element having an electron injection layer in which three layers, a layer made of a metal oxide, a layer made of a polyamine, and a layer made of a hydrophobic polymer, are stacked in this order from the cathode side.

[0004] Japanese Patent Publication No. 2019-201094

[0005] However, in the case of the electron injection layer provided in the organic light-emitting element described in Patent Document 1, the transport direction of electrons as carriers is random, which causes a problem of no directionality in carrier movement, resulting in a decrease in luminous efficiency.

[0006] Furthermore, in the case of a display device including a plurality of organic light-emitting elements described in Patent Document 1, in which the electron injection layer is formed as a single layer common to each of the plurality of organic light-emitting elements, there is a problem in that the image quality of the display device is degraded due to crosstalk occurring between adjacent organic light-emitting elements of the plurality of organic light-emitting elements via the electron injection layer.

[0007] An object of one aspect of the present disclosure is to provide a light-emitting element and a method for manufacturing the light-emitting element that can achieve low-voltage driving and improved light-emitting efficiency, and a display device and a method for manufacturing the display device that can achieve low power consumption and improved image quality.

[0008] In order to solve the above-mentioned problems, the light-emitting element of the present disclosure includes a lower electrode; an upper electrode provided above the lower electrode; and a light-emitting layer provided between the lower electrode and the upper electrode, wherein a first stack is provided between the lower electrode and the light-emitting layer, in which a first layer including a first conjugated polymer, a first ionic layer, and a second layer including a second conjugated polymer are stacked in this order from the lower electrode side, the first conjugated polymer includes a first side chain extending into the first ionic layer, and the second conjugated polymer includes a second side chain extending into the first ionic layer.

[0009] In order to solve the above-mentioned problems, the display device of the present disclosure includes a plurality of the light-emitting elements, wherein the plurality of light-emitting elements include a first light-emitting element having a first light-emitting layer as the light-emitting layer, and a second light-emitting element having a second light-emitting layer as the light-emitting layer, the second light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the first light-emitting layer, the upper electrode provided for each of the first light-emitting element and the second light-emitting element is provided as a single electrode common to each of the first light-emitting element and the second light-emitting element, the lower electrode provided for each of the first light-emitting element and the second light-emitting element is an island-shaped electrode provided individually for each of the first light-emitting element and the second light-emitting element, and the first stack is provided as a single layer common to each of the first light-emitting element and the second light-emitting element.

[0010] In order to solve the above-mentioned problems, the method for manufacturing a light-emitting element according to the present disclosure includes: a first step of forming a lower electrode; a second step of forming a first layer containing a first conjugated polymer; a third step of forming a first ionic layer; a fourth step of forming a second layer containing a second conjugated polymer; a fifth step of forming a light-emitting layer; and a sixth step of forming an upper electrode, wherein in the second step and the third step, the first layer and the first ionic layer are formed such that first side chains contained in the first conjugated polymer extend into the first ionic layer, and in the fourth step, the second layer is formed such that second side chains contained in the second conjugated polymer extend into the first ionic layer.

[0011] In order to solve the above-mentioned problems, the manufacturing method of the display device of the present disclosure includes the steps of: forming a first light-emitting element and a second light-emitting element in the manufacturing method of the light-emitting element; forming the lower electrodes provided in the first light-emitting element and the second light-emitting element, respectively, as island-shaped electrodes individually for the first light-emitting element and the second light-emitting element, in the first step; forming the first layer as a single layer common to the first light-emitting element and the second light-emitting element, in the third step; forming the first ion layer as a single layer common to the first light-emitting element and the second light-emitting element, in the fourth step; forming the second layer as a single layer common to the first light-emitting element and the second light-emitting element, in the fifth step; forming, as the light-emitting layers, a first light-emitting layer provided in the first light-emitting element and a second light-emitting layer provided in the second light-emitting element, the second light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the first light-emitting layer; and forming the upper electrodes provided in the first light-emitting element and the second light-emitting element, respectively, as a single electrode common to the first light-emitting element and the second light-emitting element.

[0012] According to one aspect of the present disclosure, it is possible to provide a light-emitting element and a method for manufacturing a light-emitting element that can achieve low-voltage driving and improved light-emitting efficiency, and a display device and a method for manufacturing a display device that can achieve low power consumption and improved image quality.

[0013] 8 is a plan view showing a schematic configuration of a display device of embodiment 1. FIG. 9 is a cross-sectional view showing a schematic configuration of a laminate provided between a lower electrode and a light-emitting layer of the display device of embodiment 1. FIG. 10 is an enlarged view of part A of FIG. 2. FIG. 11 is a cross-sectional view showing a schematic configuration of a display device of embodiment 1. FIG. 12 is a cross-sectional view showing a schematic configuration of a laminate provided between a lower electrode and a light-emitting layer of the display device of embodiment 1. FIG. 13 is a cross-sectional view showing a schematic configuration of a laminate and an insertion layer provided between an upper electrode and a light-emitting layer of the display device of embodiment 1. FIG. 14 is a diagram showing an example of a method for manufacturing a light-emitting element provided in the display device of embodiment 1. FIG. 15 is a cross-sectional view showing a schematic configuration of a laminate provided between a lower electrode and a light-emitting layer of the display device of embodiment 2. FIG. 16 is an enlarged view of part B of FIG. 15. FIG. 16 is a cross-sectional view showing a schematic configuration of a display device of embodiment 3. FIG. 17 is a cross-sectional view showing a schematic configuration of a display device of embodiment 4. FIG. 18 is a cross-sectional view showing a schematic configuration of a laminate provided between a lower electrode and a light-emitting layer of the display device of embodiment 4, and a laminate and an insertion layer provided between an upper electrode and a light-emitting layer.

[0014] The following describes an embodiment of the present disclosure with reference to Figures 1 to 12. 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.

[0015] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0016] 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.

[0017] 2 is a cross-sectional view showing a schematic configuration of a laminate 8 provided between a lower electrode 6 and a light-emitting layer (the red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE shown in FIG. 4) of the display device 1 of embodiment 1. FIG. 3 is an enlarged view of portion A in FIG. 2. FIG. 4 is a cross-sectional view showing a schematic configuration of the display device 1 of embodiment 1. FIG. 5 is a cross-sectional view showing a schematic configuration of a laminate 8 provided between a lower electrode 6 and a light-emitting layer (the red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE shown in FIG. 4) of the display device 1 of embodiment 1. FIG. 6 is a cross-sectional view showing a schematic configuration of a laminate 11 and an insertion layer OX4 provided between an upper electrode 12 and a light-emitting layer (the red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE shown in FIG. 4) of the display device 1 of embodiment 1.

[0018] 2, the display device 1 includes an active substrate 7 and a stacked body 8 provided on the active substrate 7. The active substrate 7 includes a substrate 2, a thin-film transistor layer 5 provided on the substrate 2, and island-shaped lower electrodes 6 provided on the thin-film transistor layer 5 for each of the red, green, and blue pixels RSP, GSP, and BSP.

[0019] The substrate 2 may be, for example, a resin substrate made of a resin material such as polyimide, or a glass substrate. In this embodiment, since the display device 1 is a flexible display device, a case where a resin substrate made of a resin material such as polyimide is used as the substrate 2 will be described as an example, but this is not limiting. If the display device 1 is a non-flexible display device, a glass substrate can be used as the substrate 2.

[0020] In this embodiment, the case where the thin-film transistor layer 5 is provided directly on the substrate 2 will be described as an example, but the present invention is not limited to this. For example, a barrier layer (not shown) may be provided between the substrate 2 and the thin-film transistor layer 5. The barrier layer is a layer that prevents foreign substances such as water and oxygen from entering the transistor 3 shown in FIG. 3 or the red light-emitting element 20R, green light-emitting element 20G, and blue light-emitting element 20B shown in FIG. 4, and can be composed of, for example, a silicon oxide film, a silicon nitride film, a silicon oxynitride film, or a laminate film thereof formed by a CVD method. The thin-film transistor layer 5 includes the transistor 3, wiring HS, and a planarization film 4.

[0021] As shown in Figure 4, the red pixel RSP shown in Figure 2 is provided with a red light-emitting element 20R including a lower electrode 6, an upper electrode 12 provided above the lower electrode 6, and a red light-emitting layer RE provided between the lower electrode 6 and the upper electrode 12, the green pixel GSP shown in Figure 2 is provided with a green light-emitting element 20G including a lower electrode 6, an upper electrode 12 provided above the lower electrode 6, and a green light-emitting layer GE provided between the lower electrode 6 and the upper electrode 12, and the blue pixel BSP shown in Figure 2 is provided with a blue light-emitting element 20B including a lower electrode 6, an upper electrode 12 provided above the lower electrode 6, and a blue light-emitting layer BE provided between the lower electrode 6 and the upper electrode 12.

[0022] Each of the red, green, and blue light-emitting layers RE, GE, and BE may be a light-emitting layer containing quantum dots (QDs) or an organic light-emitting material, which may be formed by, for example, a vapor deposition method.

[0023] As shown in Figures 2 and 4, between the lower electrode 6 and the red light-emitting layer RE, between the lower electrode 6 and the green light-emitting layer GE, and between the lower electrode 6 and the blue light-emitting layer BE, there is provided a laminate (first laminate) 8, which is formed by laminating, in this order from the lower electrode 6 side, a first layer CP1 containing a first conjugated polymer, a first ionic layer IL1, and a second layer CP1' containing a second conjugated polymer.

[0024] As shown in Figures 3 and 5, the first conjugated polymer contained in the first layer CP1 includes a first side chain SC1 extending into the first ionic layer IL1, and the second conjugated polymer contained in the second layer CP1' includes a second side chain SC1' extending into the first ionic layer IL1.

[0025] As shown in FIG. 3 , holes or electrons, which are carriers supplied from the lower electrode 6, move in a single direction, i.e., from the first layer CP1 to the second layer CP1′, via the first side chain SC1 of the first conjugated polymer, the first ion layer IL1, and the second side chain SC1′ of the second conjugated polymer. Therefore, in a planar view, only a partial region CTR of the stack (first stack) 8 that is provided so as to overlap the lower electrode 6 is the region through which carriers are transported. Compared to a case in which a carrier transport film with no directionality of carrier movement, i.e., in which carriers move in random directions, is provided between the lower electrode 6 and the light-emitting layer, the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B each include the stack (first stack) 8, which is a carrier transport film with directionality of carrier movement, that moves the holes or electrons, which are carriers supplied from the lower electrode 6, toward the light-emitting layer (the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE shown in FIG. 4 ), thereby improving the luminous efficiency. Furthermore, in the laminate (first laminate) 8 including the first ion layer IL1, compared to a conventional single-layer carrier transport film that realizes carrier movement only by oxidation-reduction, part of the carrier transport is carried out via ions by the first ion layer IL1, so that oxidation-reduction stress of the laminate (first laminate) 8 is reduced, thereby realizing a longer life for each of the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B. Furthermore, in the laminate (first laminate) 8 including the first ion layer IL1, the carrier mobility (10 -３ ~10 -６ cm ２ V -１ s -１ ) compared to, for example, 1 cm ２ V -１ s -１Since a carrier mobility as high as about 1000 keV can be achieved, the driving voltage of each of the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B can be reduced. Therefore, low power consumption can be achieved in a display device including the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B, or in an electronic product (e.g., a lighting device) including at least one of the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B.

[0026] As shown in FIG. 4 , the display device 1 includes a red light-emitting element (first light-emitting element) 20R having a red light-emitting layer (first light-emitting layer) RE, a green light-emitting element (second light-emitting element) 20G having a green light-emitting layer (second light-emitting layer) GE having an emission peak wavelength shorter than the emission peak wavelength of the red light-emitting layer RE, and a blue light-emitting element (third light-emitting element) 20B having a blue light-emitting layer (third light-emitting layer) BE having an emission peak wavelength shorter than the emission peak wavelength of the green light-emitting layer GE.

[0027] As shown in FIG. 4 , the upper electrodes 12 provided on the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B are provided as a single electrode common to the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B. Also, as shown in FIG. 4 , the lower electrodes 6 provided on the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B are island-shaped electrodes individually provided for the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B. As shown in FIG. 4 , the above-described stacked body (first stacked body) 8 is provided as a single layer common to the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B. In this embodiment, a case where the stacked body (first stacked body) 8 is provided as a single layer common to the red light-emitting elements 20R, green light-emitting elements 20G, and blue light-emitting elements 20B will be described as an example, but the present invention is not limited thereto. For example, the laminate (first laminate) 8 may be provided as a single layer common to only two adjacent light-emitting elements among the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B.

[0028] In the display device 1, according to the laminate (first laminate) 8 provided as one common layer, as described above, the carrier transport direction is unidirectional, so that it is possible to suppress crosstalk between adjacent pixels among the red pixel RSP, the green pixel GSP, and the blue pixel BSP, thereby suppressing display color mixing and improving image quality in the display device 1. Furthermore, conventional single-layer carrier transport films often have an amorphous structure, making it difficult to ensure flexibility, and when a display device including multiple layers of such conventional single-layer carrier transport films having an amorphous structure is bent, film peeling easily occurs due to stress between the layers. On the other hand, in the case of the laminate (first laminate) 8 provided in the display device 1, the first layer CP1 containing the first conjugated polymer and the second layer CP1' containing the second conjugated polymer each have high flexibility like rubber, and the first ionic layer IL1 is in a gel state at room temperature and therefore has high flexibility. Therefore, when the display device 1 including one or more layers of the laminate (first laminate) 8 is bent, interlayer stress can be suppressed and film peeling can be suppressed. Therefore, in the display device 1 including one or more layers of the laminate (first laminate) 8, bending with a smaller radius of curvature R is possible, and the display device can also be rolled or stretched. Furthermore, as described above, the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B included in the display device 1 each achieve a long life and a reduced driving voltage, so that the display device 1 can be extended in life and its power consumption can be reduced.

[0029] In this embodiment, an example will be described in which the lower electrode 6 provided on the display device 1 is an anode and the upper electrode 12 provided on the display device 1 is a cathode, but this is not limited to this, and as will be described later, the lower electrode 6 provided on the display device 1 may be a cathode and the upper electrode 12 provided on the display device 1 may be an anode.

[0030] In this embodiment, the red light-emitting element 20R, green light-emitting element 20G, and blue light-emitting element 20B shown in FIG. 4 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 20R, green light-emitting element 20G, and blue light-emitting element 20B each have a forward stack structure in which the upper electrode 12 (cathode) is disposed above the lower electrode 6 (anode). In this case, to achieve a top-emission structure, the lower electrode 6 (anode) may be formed from an electrode material that reflects visible light, and the upper electrode 12 (cathode) may be formed from an electrode material that transmits visible light. To achieve a bottom-emission structure, the lower electrode 6 (anode) may be formed from an electrode material that transmits visible light, and the upper electrode 12 (cathode) 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 electrode 12, which is an anode, is arranged as a layer above the lower electrode 6, which is a cathode, a top emission type can be achieved by forming the lower electrode 6, which is a cathode, from an electrode material that reflects visible light, and the upper electrode 12, which is an anode, from an electrode material that transmits visible light, and a bottom emission type can be achieved by forming the lower electrode 6, which is a cathode, from an electrode material that transmits visible light, and the upper electrode 12, which is an anode, from an electrode material that reflects visible light.

[0031] 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.

[0032] 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.

[0033] When the lower electrode 6 is an anode and the upper electrode 12 is a cathode, as shown in FIG. 4 , a stack (first stack) 8 provided as a single common layer between each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE and each of the plurality of lower electrodes 6 functions as at least one of a hole transport layer and a hole injection layer.

[0034] Although not shown, a second stack may be provided between each of the plurality of lower electrodes 6 and the stack (first stack) 8. The second stack may include a third layer including a third conjugated polymer, a second ionic layer, and a fourth layer including a fourth conjugated polymer, stacked in this order from the lower electrode 6 side. The third conjugated polymer includes a third side chain extending into the second ionic layer, and the fourth conjugated polymer includes a fourth side chain extending into the second ionic layer. The second stack is provided as a single layer common to the first light-emitting element and the second light-emitting element. In this case, the stack (first stack) 8 functions as a hole transport layer, and the second stack functions as a hole injection layer.

[0035] 4 , a stack (third stack) 9 may be provided between the upper electrode 12 and each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE. The stack (third stack) 9 includes a fifth layer CP2 including a fifth conjugated polymer, a third ionic layer IL2, and a sixth layer CP2′ including a sixth conjugated polymer, stacked in this order. The fifth conjugated polymer includes a fifth side chain extending into the third ionic layer IL2, and the sixth conjugated polymer includes a sixth side chain extending into the third ionic layer IL2. The stack (third stack) 9 is provided as a single layer common to the red light-emitting element 20R, the green light-emitting layer 20G, and the blue light-emitting layer 20B.

[0036] 4 , a stack (fourth stack) 10 may be provided between the upper electrode 12 and the stack (third stack) 9, in which a seventh layer CP3 including a seventh conjugated polymer, a fourth ionic layer IL3, and an eighth layer CP3′ including an eighth conjugated polymer are stacked in this order from the stack (third stack) 9 side. The seventh conjugated polymer includes a seventh side chain extending into the fourth ionic layer IL3, and the eighth conjugated polymer includes an eighth side chain extending into the fourth ionic layer IL3, and the stack (fourth stack) 10 is provided as a single layer common to each of the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B.

[0037] 4 , a stack (fifth stack) 11 may be provided between the upper electrode 12 and the stack (fourth stack) 10, in which a ninth layer CP4 including a ninth conjugated polymer, a fifth ionic layer IL4, and a tenth layer CP4′ including a tenth conjugated polymer are stacked in this order from the stack (fourth stack) 10 side. The ninth conjugated polymer includes a ninth side chain extending into the fifth ionic layer IL4, and the tenth conjugated polymer includes a tenth side chain extending into the fifth ionic layer IL4. The stack (fifth stack) 11 is provided as a single layer common to the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B.

[0038] 4 and 6, an insertion layer OX4 containing an inorganic electron injection material or an organic electron injection material may be provided so as to contact the stack (fifth stack) 11 and the upper electrode 12. In this case, the stack (fifth stack) 11 and the insertion layer OX4 constitute a stack (sixth stack) 11'. For example, a metal oxide or an inorganic salt can be used as the inorganic electron injection material, and a polymer material can be used as the organic electron injection material. For example, a low work function material such as TiO ２ , ZnO, ZrO ２ As the inorganic salt, a low work function material such as LiF, CsF, NaF, or MgF can be preferably used. ２ , CaF ２ , Cs ２ CO ３ In this embodiment, as the polymer material, for example, polyethylenimine ethoxylated (PEIE) or the like can be suitably used, which can realize a low work function of the upper electrode 12 serving as a cathode by surface modification of the upper electrode 12 serving as a cathode.

[0039] As shown in FIG. 4 , when a stack (third stack) 9, a stack (fourth stack) 10, and a stack (sixth stack) 11′ are stacked in this order from the lower electrode 6 side between the upper electrode 12 and the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE, respectively, the stack (third stack) 9 functions as a hole blocking layer, the stack (fourth stack) 10 functions as an electron transport layer, and the stack (sixth stack) 11′ functions as an electron injection layer. Furthermore, when the insertion layer OX4 is not provided and the stack (third stack) 9, the stack (fourth stack) 10, and the stack (fifth stack) 11 are stacked in this order from the lower electrode 6 side between the upper electrode 12 and the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE, respectively, the stack (third stack) 9 functions as a hole blocking layer, the stack (fourth stack) 10 functions as an electron transport layer, and the stack (fifth stack) 11 functions as an electron injection layer.

[0040] The first to tenth conjugated polymers may all be made of the same material, or may be made of partially or entirely different materials. The first to fifth ionic layers may all be made of the same material, or may be made of partially or entirely different materials.

[0041] The lower electrode 6 provided in the display device 1 may be a cathode, and the upper electrode 12 provided in the display device 1 may be an anode. In this case, although not shown, an insertion layer OX4 containing an inorganic electron injection material or an organic electron injection material may be provided so as to be in contact with each of the stacked body (first stacked body) 8 and the plurality of lower electrodes 6, and the stacked body (first stacked body) 8 may be in contact with each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE.

[0042] In this embodiment, as shown in FIG. 5, poly(2-(3,3′-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2′-bithiophen]-5-yl) thieno[3,2-b]thiophene) shown in the following (chemical formula 1) is used as the first conjugated polymer contained in the first layer CP1, but the present invention is not limited thereto. The first conjugated polymer has substituents R1 to R4 and a first side chain SC1 of (CH ３ -O-CH ２ -CH ２ -O-CH ２ -CH ２ -O-CH ２ -CH ２ In this embodiment, as shown in FIG. 5, poly(2-(3,3′-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2′-bithiophen]-5-yl) thieno[3,2-b]thiophene) shown in the following (Chemical Formula 1) is used as the second conjugated polymer contained in the second layer CP1′, but the present invention is not limited thereto. The second conjugated polymer contains substituents R5 to R8 and a second side chain SC1′ containing (CH ３ -O-CH ２ -CH ２ -O-CH ２ -CH ２-O-CH ２ -CH ２ -O-) is contained.

[0043] 4 , the first layer CP1 adjacent to the lower electrode 6 serving as an anode functions as a hole injection layer, and the second layer CP1′ adjacent to the laminate (third stack) 9 serving as a hole blocking layer and an electron transport layer and the first ion layer IL1 function as hole transport layers. In order to transport holes supplied from the lower electrode 6 serving as an anode with fewer barriers, it is preferable that the energy levels of the valence band top (VBM) become shallower in a stepped manner as they approach the red-light-emitting layer RE, the green-light-emitting layer GE, and the blue-light-emitting layer BE in the stack (first stack) 8. Therefore, the energy level of the top of the valence band (VBM) of the second conjugated polymer having the substituents R5 to R8 contained in the second layer CP1', which is provided closer to the red-emitting layer RE, the green-emitting layer GE, and the blue-emitting layer BE than the first layer CP1, is preferably shallower than the energy level of the top of the valence band (VBM) of the first conjugated polymer having the substituents R1 to R4 contained in the first layer CP1. Therefore, it is preferable to use, as the substituents R1 to R4, an electron-withdrawing group that serves to deepen the energy level, as described later, and it is preferable to use, as the substituents R5 to R8, an electron-donating group that serves to shallow the energy level, as described later.

[0044] Furthermore, although not shown, when a second laminate in which a third layer including a third conjugated polymer, a second ion layer, and a fourth layer including a fourth conjugated polymer are laminated in this order from the bottom electrode 6 side is provided between each of the plurality of bottom electrodes 6 and the laminate (first laminate) 8, it is preferable that the energy level of the valence band top (VBM) of the fourth conjugated polymer is shallower than the energy level of the valence band top (VBM) of the third conjugated polymer, the energy level of the valence band top (VBM) of the first conjugated polymer is shallower than the energy level of the valence band top (VBM) of the fourth conjugated polymer, and the energy level of the valence band top (VBM) of the second conjugated polymer is shallower than the energy level of the valence band top (VBM) of the first conjugated polymer. Therefore, it is preferable that the third conjugated polymer and the fourth conjugated polymer use, as a substituent, an electron-withdrawing group that serves to deepen the energy level described later, and it is preferable that the first conjugated polymer and the second conjugated polymer use, as a substituent, an electron-donating group that serves to shallow the energy level described later.

[0045] The electron donating group is, for example, an amine group (—NH ２ , -NHR １ , -NR １ R ２ (where R １ and R ２ The electron-withdrawing group may be, but is not limited to, a hydroxy group (—OH), an ether group (—OR (where R is an alkyl group or an aryl group)), an alkyl group, or an aryl group. In addition, the electron-withdrawing group may be, for example, a cyano group (CN—), a carbonyl group (—COCH ３ or —COR (where R is an alkyl group or an aryl group), an aldehyde group (—CHO), a nitro group (—NO ２ ), sulfo group (—SO ３The alkyl group may be any one of, but is not limited to, a carboxy group (—H), a carboxyl group (—COOH), an ester group (—COOR (wherein R is an alkyl group or an aryl group)), and a halogen group (—X (wherein X is a halogen element, such as F, Cl, Br, or I)).

[0046] In this embodiment, as shown in FIG. 6, poly(2-(3,3′-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2′-bithiophen]-5-yl) thieno[3,2-b]thiophene) shown in the above (Chemical Formula 1) was used as the tenth conjugated polymer contained in the tenth layer CP4′, but the present invention is not limited thereto. The tenth conjugated polymer includes substituents R13 to R16 and a tenth side chain SC4′ represented by (CH ３ -O-CH ２ -CH ２ -O-CH ２ -CH ２ -O-CH ２ -CH ２ In this embodiment, as shown in FIG. 6, poly(2-(3,3′-bis(2-(2-(2-methoxyethoxy)ethoxy)ethoxy)-[2,2′-bithiophen]-5-yl) thieno[3,2-b]thiophene) shown in the above (Chemical Formula 1) is used as the ninth conjugated polymer contained in the ninth layer CP4, but the present invention is not limited thereto. The ninth conjugated polymer contains substituents R9 to R12 and a ninth side chain SC4 that is (CH ３ -O-CH ２ -CH ２ -O-CH ２ -CH ２ -O-CH ２ -CH ２ -O-) is contained.

[0047] The stack (sixth stack) 11′ shown in FIG. 4 functions as an electron injection layer, the stack (fourth stack) 10 shown in FIG. 4 functions as an electron transport layer, and the stack (third stack) 9 shown in FIG. 4 functions as a hole blocking layer and an electron transport layer. The stack (fifth stack) 11, which does not include the insertion layer OX4, also functions as an electron injection layer. To efficiently transport electrons supplied from the upper electrode 12, which serves as a cathode, through the insertion layer OX4 with fewer barriers, it is preferable that the energy levels of the conduction band minimum (CBM) of the layers provided between the light-emitting layers (red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE) and the insertion layer OX4 become deeper in a stepped manner as they approach the red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE. Therefore, it is preferable that the energy level of the conduction band minimum (CBM) of the laminate (third laminate) 9 is deeper than the energy level of the conduction band minimum (CBM) of the laminate (fourth laminate) 10, and that the energy level of the conduction band minimum (CBM) of the laminate (fourth laminate) 10 is deeper than the energy level of the conduction band minimum (CBM) of the laminate (fifth stack) 11. In the laminate (fifth stack) 11, it is preferable that the energy level of the conduction band minimum (CBM) of the ninth conjugated polymer having substituents R9 to R12 contained in the ninth layer CP4 provided closer to the light-emitting layers (red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE) is deeper than the energy level of the conduction band minimum (CBM) of the tenth conjugated polymer having substituents R13 to R16 contained in the tenth layer CP4′. In the laminate (fourth laminate) 10, the energy level of the conduction band minimum (CBM) of the seventh conjugated polymer having a substituent contained in the seventh layer CP3 provided closer to the light-emitting layers (the red-emitting layer RE, the green-emitting layer GE, and the blue-emitting layer BE) is preferably deeper than the energy level of the conduction band minimum (CBM) of the eighth conjugated polymer having a substituent contained in the eighth layer CP3'. In the laminate (third laminate) 9, the energy level of the conduction band minimum (CBM) of the fifth conjugated polymer having a substituent contained in the fifth layer CP2 provided closer to the light-emitting layers (the red-emitting layer RE, the green-emitting layer GE, and the blue-emitting layer BE) is preferably deeper than the energy level of the conduction band minimum (CBM) of the sixth conjugated polymer having a substituent contained in the sixth layer CP2'.Therefore, it is preferable to use an electron-donating group that serves to shallow the energy level as the substituent of the eighth conjugated polymer contained in the eighth layer CP3′, the substituents R9 to R12 of the ninth conjugated polymer contained in the ninth layer CP4, and the substituents R13 to R16 of the tenth conjugated polymer contained in the tenth layer CP4′, and it is preferable to use an electron-withdrawing group that serves to deepen the energy level as the substituent of the fifth conjugated polymer contained in the fifth layer CP2, the substituent of the sixth conjugated polymer contained in the sixth layer CP2′, and the substituent of the seventh conjugated polymer contained in the seventh layer CP3.

[0048] Although not shown, the lower electrode 6 provided in the display device 1 is a cathode, and the upper electrode 12 provided in the display device 1 is an anode. An insertion layer OX4 containing an inorganic electron injection material or an organic electron injection material is provided so as to be in contact with the stack (first stack) 8 and each of the plurality of lower electrodes 6. When the stack (first stack) 8 is in contact with each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE, it is preferable that the energy level of the conduction band minimum (CBM) in the stack (first stack) 8 becomes deeper in a stepped manner as it gets closer to the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE, in order to transport electrons supplied from the lower electrode 6, which is the cathode, with fewer barriers. Therefore, it is preferable that the energy level of the conduction band minimum (CBM) of the second conjugated polymer having the substituents R5 to R8 contained in the second layer CP1', which is provided closer to the red-emitting layer RE, the green-emitting layer GE, and the blue-emitting layer BE than the first layer CP1, is deeper than the energy level of the conduction band minimum (CBM) of the first conjugated polymer having the substituents R1 to R4 contained in the first layer CP1. Therefore, it is preferable to use, as the substituents R1 to R4, electron-donating groups that serve to shallow the above-mentioned energy levels, and it is preferable to use, as the substituents R5 to R8, electron-withdrawing groups that serve to deepen the above-mentioned energy levels.

[0049] As described above, the chemical structures of the main chains and substituents of each of the first to tenth conjugated polymers can be easily changed, and therefore, it is possible to adjust the energy level of each conjugated polymer to match the energy level of the surrounding materials, thereby enabling optimization of the luminous efficiency of the display device 1.

[0050] The first to fifth ion layers shown in Figure 4 contain multiple cations and multiple anions. The multiple cations may be one or more selected from 1-alkyl-3-alkyl imidazolium shown in Chemical Formula 4 below, 1-alkyl pyridinium shown in Chemical Formula 5 below, N-alkyl-N-alkyl pyrrolidinium shown in Chemical Formula 6 below, Tetraalkyl ammonium shown in Chemical Formula 7 below, and Tetraalkyl phosphonium shown in Chemical Formula 8 below. In this embodiment, 1-methyl-3-ethyl imidazolium shown in Chemical Formula 2 below was used as the multiple cations. The multiple anions may be one or more selected from Bis(trifluoromethanesulfonyl)imide shown in Chemical Formula 3 below, Bis(fluorosulfonyl)imide shown in Chemical Formula 9 below, Dicyanamide shown in Chemical Formula 10 below, Tetracyanoborate shown in Chemical Formula 11 below, Trifluoromethanesulfonate shown in Chemical Formula 12 below, Alkyl-sulfonate shown in Chemical Formula 13 below, Acetate shown in Chemical Formula 14 below, Alkyl-phosphonate shown in Chemical Formula 15 below, Tetrafluoroborate shown in Chemical Formula 16 below, and Hexafluorophosphate shown in Chemical Formula 17 below. In this embodiment, Bis(trifluoromethanesulfonyl)imide shown in Chemical Formula 3 below was used as the multiple anions.

[0051] It is preferable that the first to tenth conjugated polymers, the first to fifth ion layers, and the insertion layer OX4 are made of materials having good transmittance for visible light.

[0052] FIG. 7 is a diagram showing an example of a method for manufacturing the light-emitting element provided in the display device 1 of the first embodiment.

[0053] Since the display device 1 includes the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B, the manufacturing method of the display device 1 includes the manufacturing method of the light emitting elements.

[0054] The manufacturing method of each of the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B includes a first step of forming a lower electrode 6 (not shown), a second step of forming a first layer CP1 including a first conjugated polymer having a first side chain SC1 (step S1 in FIG. 7), a third step of forming a first ionic layer IL1 (step S2 in FIG. 7), a fourth step of forming a second layer CP1′ including a second conjugated polymer having a second side chain SC1′ (steps S3 and S4 in FIG. 7), a fifth step of forming a light-emitting layer of the corresponding color (not shown), and a sixth step of forming an upper electrode 12. In the second step (step S1 in FIG. 7 ) and the third step (step S2 in FIG. 7 ), the first layer CP1 and the first ionic layer IL1 are formed so that the first side chain SC1 contained in the first conjugated polymer extends into the first ionic layer IL1, and in the fourth step (steps S3 and S4 in FIG. 7 ), the second layer CP1′ is formed so that the second side chain SC1′ contained in the second conjugated polymer extends into the first ionic layer IL1.

[0055] As shown in FIG. 7 , in this embodiment, in the fourth step (steps S3 and S4 of FIG. 7 ), a stamp STP is used to transfer and form a second layer CP1′ on the first ionic layer IL1. The stamp STP is, for example, a substrate (mold) made of polydimethylsiloxane. As shown in step S3 of FIG. 7 , the stamp STP, with the second layer CP1′ provided on the first ionic layer IL1 side of the stamp STP, is lowered toward the first ionic layer IL1 to form the second layer CP1′ on the first ionic layer IL1 so that the second side chain SC1′ contained in the second conjugated polymer extends into the first ionic layer IL1. Thereafter, as shown in step S4 of FIG. 7 , the stamp STP is raised upward to separate the stamp STP from the second layer CP1′. As described above, in this embodiment, the stamp STP is used in the fourth step. However, this is not limiting. For example, the second layer CP1′ may be formed in the fourth step using a dip coating method. In order to form the second layer CP1' so that the second side chains SC1' contained in the second conjugated polymer extend into the first ionic layer IL1, time is required for the molecules to align, so it is preferable to use the stamp STP method or dip coating method described above. Note that the second step of forming the first layer CP1 may use, for example, a coating method such as spin coating or slit coating, or may also use dip coating.

[0056] In the method for manufacturing the light-emitting elements described above, which is included in the method for manufacturing the display device 1, the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B are formed. In the first step of forming the lower electrodes 6 (not shown), the lower electrodes 6 provided in the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B are formed as island-shaped electrodes individually for the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B. In the second step (step S1 in FIG. 7 ), the first layer CP1 is formed as a single layer common to the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B. In the third step (step S2 in FIG. 7 ), the first ion layer IL1 is formed as a single layer common to the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B. In the fourth step (steps S3 and S4 in FIG. 7 ), the second layer CP1′ is formed as a single layer common to the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B. In the fifth step (not shown), the light emitting layers are formed as a red light emitting layer RE provided in the red light emitting element 20R, a green light emitting layer GE provided in the green light emitting element 20G, and a blue light emitting layer BE provided in the blue light emitting element 20B. In the sixth step (not shown), the upper electrodes 12 provided in the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B are formed as a single electrode common to the red light emitting element 20R, the green light emitting element 20G, and the blue light emitting element 20B.

[0057] According to the above-described methods for manufacturing the light-emitting element and the display device 1, the first layer CP1, the first ion layer IL1, and the second layer CP1' can be formed without using expensive vapor deposition equipment, thereby reducing manufacturing costs.

[0058] [Embodiment 2] Fig. 8 is a cross-sectional view showing a schematic configuration of a laminate (first laminate) 8 provided between a lower electrode 6 and a light-emitting layer of a display device 1a of embodiment 2. Fig. 9 is an enlarged view of part B in Fig. 8.

[0059] The active substrate 7 provided in the display device 1a shown in Fig. 8 differs from the active substrate 7 provided in the display device 1 shown in Fig. 2 of the first embodiment in that it includes a bank BK. The bank BK is also called a pixel defining layer (PDL). The bank BK has, for example, a function to prevent short circuits between the anode and cathode and a function to determine the positions of the red pixel RSP, the green pixel GSP, and the blue pixel BSP.

[0060] 9 , even in a display device 1a including an active substrate 7 having a bank BK, holes or electrons, which are carriers supplied from the lower electrode 6, move toward the corresponding light-emitting layer via the first side chain SC1 of the first conjugated polymer, the first ion layer IL1, and the second side chain SC1′ of the second conjugated polymer. Therefore, in plan view, only a partial region CTR of the stack (first stack) 8 provided so as to overlap with the lower electrode 6 exposed through the opening of the bank BK becomes a region through which carriers are transported.

[0061] In the display device 1a, the laminate (first laminate) 8 provided as a single common layer allows carriers to move toward the corresponding light-emitting layer, as described above, thereby suppressing crosstalk between adjacent pixels among the red pixel RSP, the green pixel GSP, and the blue pixel BSP, thereby suppressing display color mixing in the display device 1a and improving image quality. Furthermore, in the case of the laminate (first laminate) 8 provided in the display device 1a, the first layer CP1 containing the first conjugated polymer and the second layer CP1′ containing the second conjugated polymer each have high flexibility like rubber, and the first ionic layer IL1 is in a gel state at room temperature, so has high flexibility. Therefore, when the display device 1a including one or more layers of the laminate (first laminate) 8 is bent, stress between the layers can be suppressed and peeling can be suppressed. Therefore, in the display device 1a including one or more layers of the laminate (first laminate) 8, bending with a smaller radius of curvature R is possible, and the display device can also be rolled or stretched. Furthermore, as described above, the red light-emitting element 20R, the green light-emitting element 20G, and the blue light-emitting element 20B included in the display device 1a each have a longer lifespan and a reduced driving voltage, thereby enabling the display device 1a to have a longer lifespan and reduce power consumption.

[0062] Third Embodiment FIG. 10 is a cross-sectional view showing a schematic configuration of a display device 1b according to a third embodiment.

[0063] 10 includes a red light-emitting element 20R′, a green light-emitting element 20G′, and a blue light-emitting element 20B′. The blue light-emitting element 20B′ differs from the blue light-emitting element 20B in the first embodiment described above in that it includes a first electron blocking layer EBL1 between the blue light-emitting layer BE and the stack (first stack) 8. The green light-emitting element 20G′ differs from the green light-emitting element 20G in the first embodiment described above in that it includes a second electron blocking layer EBL2 between the green light-emitting layer GE and the stack (first stack) 8. The red light-emitting element 20R′ differs from the red light-emitting element 20R in the first embodiment described above in that it includes a third electron blocking layer EBL3 between the red light-emitting layer RE and the stack (first stack) 8.

[0064] 10 , each of the red light-emitting element 20R′, the green light-emitting element 20G′, and the blue light-emitting element 20B′ forms a cavity structure (also referred to as a microcavity structure) with the lower electrode 6 and the upper electrode 12. In the blue light-emitting element 20B′, the first electron blocking layer EBL1 is formed thinner than the second electron blocking layer EBL2 and the third electron blocking layer EBL3, and the distance between the lower electrode 6 and the upper electrode 12 is shorter than in the red light-emitting element 20R′ and the green light-emitting element 20G′, so that the lower electrode 6 and the upper electrode 12 resonate and emit blue light in a stimulated manner. In the green light-emitting element 20G′, the second electron blocking layer EBL2 is formed thicker than the first electron blocking layer EBL1 and thinner than the third electron blocking layer EBL3, and the distance between the lower electrode 6 and the upper electrode 12 is longer than in the blue light-emitting element 20B′ but shorter than in the red light-emitting element 20R′, so that the lower electrode 6 and the upper electrode 12 resonate and emit green light in a stimulated manner. In the red light-emitting element 20R', the third electron blocking layer EBL3 is formed thicker than the first electron blocking layer EBL1 and the second electron blocking layer EBL2, and the distance between the lower electrode 6 and the upper electrode 12 is longer than in the blue light-emitting element 20B' and the green light-emitting element 20G', so that the lower electrode 6 and the upper electrode 12 resonate and induce emission of red light.

[0065] Unlike the above-described stack (first stack) 8, each of the first electron blocking layer EBL1, the second electron blocking layer EBL2, and the third electron blocking layer EBL3 is a single layer, and can be formed using a conventional electron blocking material.

[0066] As described above, even in the display device 1b including the red light emitting element 20R', the green light emitting element 20G', and the blue light emitting element 20B' each having a cavity structure, the laminate (first laminate) 8 provided as a single common layer has a single carrier transport direction, as described above, so that crosstalk between adjacent pixels among the red pixel RSP, the green pixel GSP, and the blue pixel BSP can be suppressed, thereby suppressing display color mixing in the display device 1b and improving image quality. In the case of the laminate (first laminate) 8 provided in the display device 1b, the first layer CP1 including the first conjugated polymer and the second layer CP1' including the second conjugated polymer each have high flexibility like rubber, and the first ionic layer IL1 is in a gel state at room temperature and therefore has high flexibility. Therefore, when the display device 1b including one or more layers of the laminate (first laminate) 8 is bent, stress between the layers can be suppressed, and peeling of the film can be suppressed. Therefore, in the display device 1b including one or more layers of the laminate (first laminate) 8, bending with a smaller radius of curvature R is possible, and the display device can also be rolled or stretched. Furthermore, as described above, the red light emitting element 20R', the green light emitting element 20G', and the blue light emitting element 20B' included in the display device 1b each achieve a long life and a reduced driving voltage, so that the display device 1b can achieve a long life and reduced power consumption.

[0067] [Embodiment 4] Fig. 11 is a cross-sectional view showing a schematic configuration of a display device 1c of embodiment 4. Fig. 12 is a cross-sectional view showing a schematic configuration of a stack (first stack) 8 provided between a lower electrode 6 and a light-emitting layer of the display device 1c of embodiment 4, and a stack (third stack) 21 and an insertion layer OX5 provided between an upper electrode 12 and a light-emitting layer.

[0068] 11 , in the display device 1c, a stack (third stack) 21 is provided between the upper electrode 12, which is a cathode, and each of the red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE, and includes a fifth layer CP5 including a fifth conjugated polymer, a third ionic layer IL5, and a sixth layer CP5′ including a sixth conjugated polymer, stacked in this order from the light-emitting layer (red light-emitting layer RE, green light-emitting layer GE, and blue light-emitting layer BE) side. As shown in FIG. 12 , the fifth conjugated polymer includes substituents R17 to R20 and a fifth side chain SC5 extending into the third ionic layer IL5, and the sixth conjugated polymer includes substituents R21 to R24 and a sixth side chain SC5′ extending into the third ionic layer IL5. The stack (third stack) 21 is provided as a single layer common to the red light-emitting element 20R", the green light-emitting layer 20G", and the blue light-emitting element 20B". An insertion layer OX5 containing an inorganic electron injection material or an organic electron injection material is provided so as to be in contact with the stack (third stack) 21 and the upper electrode 12, and the stack (third stack) 21 is in contact with each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE. In this case, the stack (third stack) 21 and the insertion layer OX5 constitute a stack (seventh stack) 21'. In this case, the fifth layer CP5 containing the fifth conjugated polymer functions as a hole blocking layer, the third ion layer IL5 and the sixth layer CP5' containing the sixth conjugated polymer function as electron transport layers, and the insertion layer OX5 functions as an electron injection layer.

[0069] According to the display device 1c, the number of laminates provided between the upper electrode 12, which is the cathode, and each of the red light-emitting layer RE, the green light-emitting layer GE, and the blue light-emitting layer BE can be reduced, thereby making it possible to realize a display device that is easier to bend and further reducing the manufacturing cost of the display device.

[0070] [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.

[0071] The present disclosure can be used in a light-emitting element, a display device, a method for manufacturing a light-emitting element, and a method for manufacturing a display device.

[0072] REFERENCE SIGNS LIST 1, 1a, 1b, 1c Display device 2 Substrate 5 Thin film transistor layer 6 Lower electrode 7 Active substrate 8 Stack (first stack) 9, 21 Stack (third stack) 10 Stack (fourth stack) 11 Stack (fifth stack) 11' Stack (sixth stack) 12 Upper electrode 20R, 20R', 20R'' Red light emitting element 20G, 20G', 20G'' Green light emitting element 20B, 20B', 20B'' Blue light emitting element 21' Stack (seventh stack) CP1 First layer IL1 First ion layer CP1' Second layer CP2, CP5 Fifth layer IL2, IL5 Third ion layer CP2', CP5' Sixth layer CP3 Seventh layer IL3 Fourth ion layer CP3' Eighth layer CP4 9th layer IL4 5th ion layer CP4' 10th layer OX4, OX5 Insertion layer SC1 1st side chain SC1' 2nd side chain SC4 9th side chain SC4' 10th side chain SC5 5th side chain SC5' 6th side chain STP Stamp BK Bank EBL1 to EBL3 1st to 3rd electron blocking layers RE Red light-emitting layer GE Green light-emitting layer BE Blue light-emitting layer R1 to R24 Substituent

Claims

1. A light-emitting device comprising: a lower electrode; an upper electrode provided above the lower electrode; and a light-emitting layer provided between the lower electrode and the upper electrode, wherein a first laminate is provided between the lower electrode and the light-emitting layer, comprising a first layer including a first conjugated polymer, a first ionic layer, and a second layer including a second conjugated polymer laminated in this order from the lower electrode side, wherein the first conjugated polymer includes a first side chain extending into the first ionic layer, and the second conjugated polymer includes a second side chain extending into the first ionic layer.

2. A display device comprising a plurality of light-emitting elements according to claim 1, wherein the plurality of light-emitting elements comprise a first light-emitting element having a first light-emitting layer as the light-emitting layer, and a second light-emitting element having a second light-emitting layer as the light-emitting layer, the second light-emitting layer having a peak emission wavelength shorter than the peak emission wavelength of the first light-emitting layer, wherein the upper electrode provided on each of the first light-emitting element and the second light-emitting element is provided as a single electrode common to the first light-emitting element and the second light-emitting element, and the lower electrode provided on each of the first light-emitting element and the second light-emitting element is an island-shaped electrode provided individually for the first light-emitting element and the second light-emitting element, and the first stack is provided as a single layer common to the first light-emitting element and the second light-emitting element.

3. The display device according to claim 2, wherein the lower electrode is an anode and the upper electrode is a cathode.

4. The display device according to claim 3, wherein a second laminate is provided between the lower electrode and the first laminate, the second laminate including a third layer including a third conjugated polymer, a second ionic layer, and a fourth layer including a fourth conjugated polymer laminated in this order from the lower electrode side, the third conjugated polymer including a third side chain extending into the second ionic layer, and the fourth conjugated polymer including a fourth side chain extending into the second ionic layer, and the second laminate is provided as a single layer common to both the first light-emitting element and the second light-emitting element.

5. The display device according to claim 3 or 4, wherein a third laminate is provided between the upper electrode and the light-emitting layer, the third laminate being formed by stacking, in this order from the light-emitting layer side, a fifth layer including a fifth conjugated polymer, a third ionic layer, and a sixth layer including a sixth conjugated polymer, the fifth conjugated polymer including a fifth side chain extending into the third ionic layer, and the sixth conjugated polymer including a sixth side chain extending into the third ionic layer, and the third laminate is provided as a single layer common to both the first light-emitting element and the second light-emitting element.

6. The display device according to claim 5, wherein an insertion layer containing an inorganic electron injection material or an organic electron injection material is provided so as to contact the third stack and the upper electrode, and the third stack is in contact with the light-emitting layer.

7. The display device according to claim 5, wherein a fourth stack is provided between the upper electrode and the third stack, the fourth stack being formed by stacking, in this order from the third stack side, a seventh layer including a seventh conjugated polymer, a fourth ionic layer, and an eighth layer including an eighth conjugated polymer, the seventh conjugated polymer including a seventh side chain extending into the fourth ionic layer, and the eighth conjugated polymer including an eighth side chain extending into the fourth ionic layer, and the fourth stack is provided as a single layer common to both the first light-emitting element and the second light-emitting element.

8. The display device according to claim 7, wherein a fifth stack is provided between the upper electrode and the fourth stack, the fifth stack being formed by stacking, in this order from the fourth stack side, a ninth layer including a ninth conjugated polymer, a fifth ionic layer, and a tenth layer including a tenth conjugated polymer, the ninth conjugated polymer including a ninth side chain extending into the fifth ionic layer, and the tenth conjugated polymer including a tenth side chain extending into the fifth ionic layer, and the fifth stack is provided as a single layer common to both the first light-emitting element and the second light-emitting element.

9. The display device according to claim 8, further comprising an insertion layer containing an inorganic electron injection material or an organic electron injection material, said insertion layer being in contact with said fifth stack and said upper electrode.

10. The display device according to claim 2, wherein the lower electrode is a cathode and the upper electrode is an anode.

11. The display device according to claim 10, wherein an insertion layer containing an inorganic electron injection material or an organic electron injection material is provided so as to contact the first stack and the lower electrode, and the first stack is in contact with the light-emitting layer.

12. The display device according to claim 3, wherein the first conjugated polymer includes an electron-withdrawing group, and the second conjugated polymer includes an electron-donating group.

13. The display device according to claim 4, wherein the first conjugated polymer and the second conjugated polymer contain an electron-donating group, and the third conjugated polymer and the fourth conjugated polymer contain an electron-withdrawing group.

14. The display device according to claim 8 or 9, wherein the fifth conjugated polymer, the sixth conjugated polymer, and the seventh conjugated polymer contain an electron-withdrawing group, and the eighth conjugated polymer, the ninth conjugated polymer, and the tenth conjugated polymer contain an electron-donating group.

15. The display device according to claim 10 or 11, wherein the first conjugated polymer contains an electron-donating group, and the second conjugated polymer contains an electron-withdrawing group.

16. The display device according to any one of claims 12 to 15, wherein the electron-withdrawing group is any one of a cyano group, a carbonyl group, an aldehyde group, a nitro group, a sulfo group, a carboxy group, an ester group, and a halogen group.

17. The display device according to any one of claims 12 to 15, wherein the electron-donating group is any one of an amine group, a hydroxy group, an ether group, an alkyl group, and an aryl group.

18. The display device according to any one of claims 2 to 17, wherein the ionic layer contains a plurality of cations and a plurality of anions.

19. The display device of claim 18, wherein the plurality of cations are one or more selected from 1-alkyl-3-alkyl imidazolium, 1-alkyl pyridinium, N-alkyl-N-alkyl pyrrolidinium, tetraalkyl ammonium, and tetraalkyl phosphonium, and the plurality of anions are one or more selected from tetrafluoroborate, hexafluorophosphate, bis(trifluoromethanesulfonyl)imide, bis(fluorosulfonyl)imide, dicyanamide, tetracyanoborate, trifluoromethanesulfonate, alkyl-sulfonate, acetate, and alkyl-phosphonate.

20. A method for manufacturing a light-emitting element, comprising: a first step of forming a lower electrode; a second step of forming a first layer containing a first conjugated polymer; a third step of forming a first ionic layer; a fourth step of forming a second layer containing a second conjugated polymer; a fifth step of forming a light-emitting layer; and a sixth step of forming an upper electrode, wherein in the second and third steps, the first layer and the first ionic layer are formed so that a first side chain contained in the first conjugated polymer extends into the first ionic layer, and in the fourth step, the second layer is formed so that a second side chain contained in the second conjugated polymer extends into the first ionic layer.

21. The method for manufacturing a light-emitting element according to claim 20, wherein in the fourth step, the second layer is transferred onto the first ion layer using a stamp.

22. The method for manufacturing a light-emitting element according to claim 20, wherein in the fourth step, the second layer is formed using a dip coating method.

23. A method for manufacturing a light-emitting element according to any one of claims 20 to 22, comprising forming a first light-emitting element and a second light-emitting element; in the first step, forming the lower electrodes provided in the first light-emitting element and the second light-emitting element individually as island-shaped electrodes for the first light-emitting element and the second light-emitting element; in the second step, forming the first layer as a single layer common to the first light-emitting element and the second light-emitting element; in the third step, forming the first ion layer as a single layer common to the first light-emitting element and the second light-emitting element; in the fourth step, forming the second layer as a single layer common to the first light-emitting element and the second light-emitting element; and in the fifth step, forming, as the light-emitting layers, a first light-emitting layer provided in the first light-emitting element and a second light-emitting layer provided in the second light-emitting element, the second light-emitting layer having an emission peak wavelength shorter than the emission peak wavelength of the first light-emitting layer. In the sixth step, the upper electrodes provided on the first light-emitting element and the second light-emitting element are formed as a single common electrode for the first light-emitting element and the second light-emitting element.

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