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

Abstract

A light-emitting element (2) is provided with at least one functional layer (22, 23, 24) positioned between an anode (21) and a cathode (25). At least one of the functional layers includes: a plurality of functional materials (31R, 31G, 31B); an inorganic matrix (41) that fills the space between at least two of the functional materials; and a photosensitive material (51).

Description

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

[0001] This disclosure relates to a light-emitting element containing quantum dots (semiconductor nanoparticles), a display device equipped with the light-emitting element, and a method for manufacturing the light-emitting element.

[0002] Patent Document 1 discloses a light-emitting device in which quantum dots are used as the light-emitting material in the light-emitting layer.

[0003] Japanese Patent Application Publication No. 2009-88276

[0004] In the light-emitting element described in Patent Document 1, deterioration of the material may occur due to the intrusion of foreign substances such as moisture or oxygen into the material such as quantum dots, or due to the conduction of heat into the material. In response to this, it is conceivable to form an adduct such as a metal oxide around the material of a specific layer in the above light-emitting element to protect the material from foreign substances or heat. However, even in this case, voids such as porosity may occur in the adduct, which may lead to a decrease in the mechanical strength of the layer containing the adduct.

[0005] A light-emitting element according to one aspect of the present disclosure comprises an anode, a cathode facing the anode, and at least one functional layer located between the anode and the cathode and including a light-emitting layer containing at least a light-emitting material, wherein at least one layer of the functional layer includes a plurality of functional materials, an inorganic matrix filling the space between at least two of the functional materials, and a photosensitive material.

[0006] A method for manufacturing a light-emitting element according to one aspect of the present disclosure is a method for manufacturing a light-emitting element comprising: forming an anode; forming a cathode facing the anode; and forming at least one functional layer located between the anode and the cathode and including a light-emitting layer containing at least a light-emitting material, wherein the formation of at least one functional layer includes forming a layer containing a plurality of functional materials, an inorganic matrix filling the space between at least two of the functional materials, and a photosensitive material.

[0007] This reduces the degradation of the functional material in the light-emitting element while also reducing the decrease in the mechanical strength of the layer containing the functional material.

[0008] This is a schematic side cross-sectional view of a display device according to Embodiment 1. This is a schematic diagram of a display device according to Embodiment 1. This is a schematic side cross-sectional view of a display device according to Modification 1. This is a schematic side cross-sectional view of a display device according to Modification 2. This is a schematic side cross-sectional view of a red light-emitting layer according to Embodiment 1. This is a schematic diagram showing an example of an inorganic matrix filling the spaces between quantum dots according to Embodiment 1. This is a flowchart of a method for manufacturing a display device according to Embodiment 1. This is a flowchart of a method for forming a light-emitting layer according to Embodiment 1. This is a process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another process cross-sectional view of a method for forming a light-emitting layer according to Embodiment 1. This is another example of a schematic side cross-sectional view of a light-emitting layer according to Embodiment 1. This is another example of a schematic side cross-sectional view of a light-emitting layer according to Embodiment 1. This is another example of a schematic side cross-sectional view of a light-emitting layer according to Embodiment 1. This is another example of a schematic side cross-sectional view of a light-emitting layer according to Embodiment 1. This is a schematic side cross-sectional view of a red light-emitting layer according to Embodiment 2. This is a schematic plan cross-sectional view of the red light-emitting layer according to Embodiment 2. This is a schematic side cross-sectional view of the red light-emitting layer according to Embodiment 3. This is a schematic side cross-sectional view of the red light-emitting layer according to Embodiment 4. This is a schematic plan cross-sectional view of the red light-emitting layer according to Embodiment 4. This is a schematic side cross-sectional view of the display device according to Embodiment 5. This is a schematic plan cross-sectional view of the display device according to Embodiment 5.

[0009] [Embodiment 1] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. In each drawing, similar components are denoted by the same reference numeral and their descriptions are omitted. Also, in this disclosure, for the sake of simplicity of illustration, the scale may differ in the drawings for components denoted by the same reference numeral, and different hatching may be applied. However, the components shown in each drawing of this disclosure are merely examples, and their scale is not limited to that shown in the drawing. Furthermore, even for components denoted by different hatching in this disclosure, components denoted by the same reference numeral have the same configuration as described above. In addition, in each drawing of this disclosure, if two components have substantially the same shape but different compositions, they may be denoted by different reference numerals but have the same hatching.

[0010] <Display Device: Overview> Figure 2 is a schematic diagram of the display device 1 according to this embodiment. The display device 1 is a device that can be used, for example, in a television or smartphone display. The display device 1 comprises a display unit DA including a plurality of subpixels and a driver circuit DR that drives the plurality of subpixels. Each of the plurality of subpixels comprises a light-emitting element 2, which will be described later, and a pixel circuit PC that drives the light-emitting element 2.

[0011] In particular, the display device 1 includes a red subpixel XR, a green subpixel XG, and a blue subpixel XB in the display unit DA. The red subpixel XR is provided with a red light-emitting element 2R that emits red light, the green subpixel XG is provided with a green light-emitting element 2G that emits green light, and the blue subpixel XB is provided with a blue light-emitting element 2B that emits blue light, each as a light-emitting element 2.

[0012] The display device 1 performs display on the display unit DA by controlling the light emitted from each of the multiple light-emitting elements 2 formed on the display unit DA via the driver circuit DR and the pixel circuit PC. In particular, the display device 1 may perform full-color display by controlling the red light from the red subpixel XR, the green light from the green subpixel XG, and the blue light from the blue subpixel XB, respectively.

[0013] In other words, the display device 1 includes a second light-emitting element 2 that emits light of a different wavelength from the first light-emitting element. Here, the first light-emitting element may be a red light-emitting element 2R, and the second light-emitting element may be a green light-emitting element 2G. Alternatively, the first light-emitting element may be a green light-emitting element 2G, and the second light-emitting element may be a blue light-emitting element 2B. Furthermore, the first light-emitting element may be a red light-emitting element 2R, and the second light-emitting element may be a blue light-emitting element 2B.

[0014] <Light-emitting element: Overview> The structure of the display unit DA of the display device 1, and in particular the structure of the light-emitting element 2, will be described in more detail with reference to Figure 1. Figure 1 is a schematic side cross-sectional view of the display device 1 according to this embodiment. All schematic side cross-sectional views of the display device 1 according to this disclosure, including Figure 1, show a cross-section perpendicular to the display surface of the display device 1 and passing through the red subpixel XR, the green subpixel XG, and the blue subpixel XB.

[0015] As shown in Figure 1, the display device 1 according to this embodiment comprises a plurality of light-emitting elements 2 and a substrate 3 in the display unit DA, and in particular, a plurality of light-emitting elements 2 are provided on the substrate 3. The display device 1 has a structure in which each layer of light-emitting elements 2 is stacked on a substrate 3 on which, for example, a TFT (Thin Film Transistor) (not shown) is formed as a pixel circuit PC. In this specification, the direction from the light-emitting elements 2 to the substrate 3 of the display device 1 is described as the "downward direction," and the direction opposite to the downward direction is described as the "upward direction."

[0016] The light-emitting element 2 comprises an anode 21, a hole transport layer 22, a light-emitting layer 23, an electron transport layer 24, and a cathode 25, in this order from the substrate 3 side. In other words, the light-emitting element 2 comprises an anode 21, a cathode 25 facing the anode 21, and between the anode 21 and the cathode 25, a hole transport layer 22, a light-emitting layer 23, and an electron transport layer 24.

[0017] In particular, the light-emitting element 2 includes a light-emitting layer 23 between the anode 21 and the cathode 25, which contains at least one light-emitting material described later. As described later, the light-emitting layer 23 has the function of emitting light due to the light-emitting material it contains. Also as described later, the hole transport layer 22 has the function of transporting holes from the anode 21 to the light-emitting layer 23, and the electron transport layer 24 has the function of transporting electrons from the cathode 25 to the light-emitting layer 23. For this reason, the hole transport layer 22, the light-emitting layer 23, and the electron transport layer 24 may each be referred to as a functional layer in this disclosure.

[0018] The following describes in more detail the configuration of each layer of the light-emitting element 2.

[0019] <Light-emitting element: electrodes> The anode 21 and cathode 25 contain a conductive material and are electrically connected to the hole transport layer 22 and electron transport layer 24, respectively. The anode 21 is formed in an island shape for each subpixel, and specifically includes anode 21R located at the red subpixel XR, anode 21G located at the green subpixel XG, and anode 21B located at the blue subpixel XB. Each of the anodes 21 is electrically connected to the pixel circuit PC of each subpixel. Anodes 21R, 21G, and 21B may be partitioned by a bank BK located on the substrate 3 and containing an organic insulating material such as polyimide. On the other hand, the cathode 25 may be formed in common for multiple subpixels, for example.

[0020] At least one of the anode 21 and cathode 25 is a transparent electrode that transmits visible light. Examples of transparent electrodes include ITO (indium tin oxide), IZO (indium zinc oxide), ZnO, AZO (aluminum-doped zinc oxide, also called ZAO), BZO (boron-doped zinc oxide), or FTO (fluorine-doped tin oxide). The transparent electrode may be formed by sputtering or the like. In addition, either the anode 21 or the cathode 25 may contain a metallic material, and as the metallic material, Al, Cu, Au, Ag, or Mg alone or alloys thereof, which have high reflectivity of visible light, are preferred.

[0021] <Light-emitting element: Charge transport layer> The hole transport layer 22 has the function of transporting holes from the anode 21 to the light-emitting layer 23, and is a layer containing multiple hole transport materials as multiple functional materials. In this embodiment, the material of the hole transport layer 22 can be an organic or inorganic material that has been conventionally used in light-emitting elements including quantum dots. For example, conductive compounds such as polyvinylcarbazole (PVK), [N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (TPD), 4,4'-bis(carbazole-9-yl)biphenyl (CBP), polyphenylenevinylene (PPV), a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (PEDOT-PSS), or poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-4-sec-butylphenyl)diphenylamine)]) (TFB) can be used as the organic material for the hole transport layer 22. In addition, other organic materials for the hole transport layer 22 include polytrialylamine semiconductor (PTAA) or [dipyradino[2,3-f:2',3'-h]quinoxaline-2,3,6,7,10,11-hexacarbonnitrile] (HAT-CN). As an inorganic material for the hole transport layer 22, molybdenum oxide (MoO) can be used. ３ ), nickel oxide (NiO), chromium oxide (Cr ２ O ３ ), magnesium oxide (MgO), lanthanum nickel oxide (LaNiO) ３ ), or tungsten oxide (WO ３Metal oxides such as ) can be used. In particular, as the material for the hole transport layer 22, a material with a small electron affinity, which is the energy difference (absolute value) between the vacuum level and the bottom of the conductor (CBM), is preferred from the viewpoint of reducing electron outflow from the light-emitting layer 23 to the hole transport layer 22. Furthermore, as the material for the hole transport layer 22, a material whose ionization potential, which is the energy difference (absolute value) between the vacuum level and the top of the valence band (VBM), is about the same as the ionization potential of the light-emitting material of the light-emitting layer 23 is preferred. This makes it possible for the light-emitting element 2 to improve the efficiency of hole transport from the anode 21 to the hole transport layer 22 and from the hole transport layer 22 to the light-emitting layer 23. Note that the chemical formulas of the compounds in this disclosure are representative examples, and the composition ratios described in the chemical formulas may be stoichiometric or not. In this embodiment, the hole transport layer 22 may also be formed on the side and top surfaces of the bank BK.

[0022] The electron transport layer 24 has the function of transporting electrons from the cathode 25 to the light-emitting layer 23, and is a layer containing multiple electron transport materials as multiple functional materials. In particular in this embodiment, the electron transport layer 24 is in contact with the light-emitting layer 23. The material of the electron transport layer 24 can be an organic or inorganic material that has been conventionally used in light-emitting devices including quantum dots. For example, the electron transport layer 24 may use zinc oxide (ZnO), zinc magnesium oxide (ZnMgO), titanium oxide (TiO), and tungsten oxide (WO) as electron transport materials. ３ The electron transport layer 24 may contain at least one of the following, and may also contain inorganic nanoparticle materials which are nanoparticles of these inorganic materials. Alternatively, the electron transport layer 24 may contain an organic material such as tris(8-quinolinol)aluminum complex (Alq3), bathocuproin (BCP), or (2-(4-biphenylyl)-5-(4-tert-butylphenyl)-1,3,4-oxadiazole) (t-Bu-PBD) as the electron transport material. As the inorganic material of the electron transport layer 24, metal oxides such as ZnO, ZAO, ITO, InGaZnO, or electride may be used. In this embodiment, a part of the electron transport layer 24 may be in contact with a part of the hole transport layer 22 formed on, for example, the bank BK.

[0023] In this embodiment, the hole transport layer 22 and the electron transport layer 24 can be formed by vacuum deposition, sputtering, or a coating method using a colloidal solution, using the materials described above. The light-emitting element 2 may also have a hole injection layer as another functional layer between the anode 21 and the hole transport layer 22, and an electron injection layer as another functional layer between the cathode 25 and the electron transport layer 24. The hole injection layer and the electron injection layer may both be formed by the same method as the hole transport layer 22 or the electron transport layer 24.

[0024] In this embodiment, the charge transport layer, including the hole transport layer 22 and the electron transport layer 24, is formed in common across multiple subpixels, but is not limited to this. For example, the charge transport layer may be partitioned for each subpixel by a component containing the same organic insulating material as the bank BK. In this case, each charge transport layer may contain an appropriate material depending on the band gap of the light-emitting material contained in the light-emitting layer described later for each subpixel. In other words, each of two light-emitting elements with different emission colors may contain a charge transport layer made of a different material.

[0025] <Light-emitting element: Light-emitting layer: Overview> The light-emitting layer 23 according to this embodiment includes a plurality of light-emitting materials as a plurality of functional materials. In particular, the light-emitting layer 23 according to this embodiment includes a plurality of light-emitting quantum dots as a plurality of light-emitting materials.

[0026] The light-emitting layer 23 also includes a red light-emitting layer 23R located at the red subpixel XR, a green light-emitting layer 23G located at the green subpixel XG, and a blue light-emitting layer 23B located at the blue subpixel XB. The red light-emitting layer 23R, the green light-emitting layer 23G, and the blue light-emitting layer 23B may be partitioned into subpixels by a bank BK and a hole transport layer 22, as shown in Figure 1.

[0027] Therefore, the red light-emitting element 2R comprises an anode 21R, a hole transport layer 22, a red light-emitting layer 23R, an electron transport layer 24, and a cathode 25, located in the red subpixel XR, in that order from the substrate 3 side. Similarly, the green light-emitting element 2G comprises an anode 21G, a hole transport layer 22, a green light-emitting layer 23G, an electron transport layer 24, and a cathode 25, located in the green subpixel XG, in that order from the substrate 3 side. Furthermore, the blue light-emitting element 2B comprises an anode 21B, a hole transport layer 22, a blue light-emitting layer 23B, an electron transport layer 24, and a cathode 25, located in the blue subpixel XB, in that order from the substrate 3 side.

[0028] The structure of the light-emitting element 2 according to this embodiment is not limited to the structure shown in Figure 1. Other examples of the structure of the light-emitting element 2 according to this embodiment will be described with reference to Figures 3 and 4. Figures 3 and 4 are schematic side cross-sectional views of the display device 1 according to Modification 1 and Modification 2 of this embodiment, and in particular, they show side cross-sections at the same position as the side cross-section shown in Figure 1.

[0029] As shown in Figure 3, the display device 1 according to Modification 1 of this embodiment may include a bank BK that partitions only the anode 21 into subpixels. In Modification 1, the light-emitting layer 23 may also be partitioned into subpixels by an electron transport layer 24. In this case, the electron transport layer 24 may be in contact not only with the upper surface but also with the side surface of each light-emitting layer located at each subpixel.

[0030] Furthermore, as shown in Figure 4, the display device 1 according to Modification 1 of this embodiment may include an electron transport layer 24 and a cathode 25 having a shape that reflects the shape of the hole transport layer 22. In particular, in Modification 2, the hole transport layer 22 and the electron transport layer 24 may have portions that protrude on the side opposite to the substrate 3 at a position that overlaps with the bank BK in a plan view of the substrate 3. In other words, in Modification 2, the hole transport layer 22 and the electron transport layer 24 may have a shape that further reflects the shape of the portion of the hole transport layer 22 that protrudes on the side opposite to the substrate 3, reflecting the shape of the bank BK.

[0031] The light-emitting layer 23 according to this embodiment will be described in more detail with reference to Figure 5. Figure 5 is a schematic side cross-sectional view of the red light-emitting layer 23R according to this embodiment. In particular, the schematic side cross-sectional views of the red light-emitting layer 23R in this disclosure, including Figure 5, are all schematic side cross-sectional views of the red light-emitting layer 23R in a plane along the film thickness direction DT of the light-emitting layer 23.

[0032] <Light-emitting element: Emitting layer: Quantum dots> As shown in Figures 1 and 5, the red emissive layer 23R includes a plurality of red quantum dots 31R as a plurality of emissive materials. The quantum dots in this disclosure, including the red quantum dots 31R, are luminescent semiconductor nanoparticles that emit light, for example, by the recombination of injected electrons and holes. The quantum dots in this disclosure may have a core / shell structure including, for example, a core and a shell covering the core. In this case, the recombination of electrons and holes in the quantum dot mainly occurs in the core. The core of the quantum dot has a valence band level and a conduction band level, and emits light by the recombination of holes in the valence band level and electrons in the conduction band level. Because the emission from quantum dots has a narrow spectrum due to the quantum confinement effect, it is possible to obtain emission with relatively deep chromaticity. The shell also has the function of suppressing the occurrence of defects or dangling bonds in the core and reducing the recombination of carriers that undergo a deactivation process. From the viewpoint of efficiently obtaining the quantum confinement effect in quantum dots, the particle size of the quantum dot core may be approximately twice or less the exciton Bohr radius of the core material.

[0033] The quantum dot may include materials used for conventionally known core and shell materials in the core and shell materials, respectively. For example, the quantum dot may have a core / shell structure of a group I-III-V chalcopyrite material / ZnS including InP / ZnS, CdSe / ZnS, CdSe / ZnSe, CdSe / CdS, ZnSe / ZnS, or CuInGaS (CIGS). In addition, the quantum dot may contain InZnP, CdSeTe, or ZnSeTe. Furthermore, the core of the quantum dot may contain CuInZnS, CuInS, CuGaS, AgInS, or ZnAgInS. The shell may be formed from multiple layers containing multiple different materials.

[0034] The particle size of the quantum dots is about 1 to 100 nm. The quantum dots may have a spherical shape or a non-spherical shape. In the present disclosure, the particle size of the quantum dots may be measured by performing cross-sectional observation in the film thickness direction DT for the light-emitting layer 23. In the cross-sectional observation, each particle size of the quantum dots may be regarded as the same as the diameter of a circle having the same area as each cross-sectional area. The particle size of the quantum dots may be measured by measuring 20 particle sizes each in the cross-sectional observation and calculating the average thereof. The cross-sectional observation may be performed by analyzing an image obtained by imaging a cross-section of each layer with a transmission electron microscope image (TEM image).

[0035] The wavelength of light emission from the quantum dots can be controlled by the particle size. In particular, since the quantum dots have a core / shell structure, the wavelength of light emission from the quantum dots can be controlled by controlling the particle size of the core. Therefore, by controlling the particle size of the quantum dots, the wavelength of light emitted by each light-emitting element can be controlled.

[0036] The red light-emitting layer 23R may contain a plurality of organic ligands coordinated to the red quantum dots 31R around the red quantum dots 31R. In this case, in the red light-emitting layer 23R, from the viewpoint of improving the reliability of the red light-emitting layer 23R, for example, the weight ratio of the organic ligand to the total weight of the red light-emitting layer 23R may be less than 5%.

[0037] <Light-emitting element: Light-emitting layer: Inorganic matrix and photosensitive material> As shown in FIGS. 1 and 5, the red light-emitting layer 23R contains an inorganic matrix 41. In the red light-emitting layer 23R, the inorganic matrix 41 fills the space between at least two red quantum dots 31R, details of which will be described later. Further, the inorganic matrix 41 has at least one of a porous portion 42 communicating with any outer surface of the red light-emitting layer 23R and a crack 43 located on either of the upper and lower surfaces.

[0038] Further, as shown in FIGS. 1 and 5, the red light-emitting layer 23R contains a photosensitive material 51. The photosensitive material 51 is a material that is modified when irradiated with light such as ultraviolet light.

[0039] In this embodiment, the photosensitive material 51 fills at least a portion of at least one of the pores 42 and cracks 43 of the inorganic matrix 41. In particular, in this embodiment, the photosensitive material 51 may fill all of each of the pores 42 and cracks 43 of the inorganic matrix 41.

[0040] <Specific Configuration of Light-Emitting Element: Light-Emitting Layer: Inorganic Matrix> The material filling the spaces between the multiple red quantum dots 31R will be described in more detail with further reference to Figure 6. Schematic diagrams F1, F2, and F3 in Figure 6 are schematic diagrams for showing the material filling the spaces between the red quantum dots 31R. In particular, schematic diagrams F1, F2, and F3 show two examples of the pair P of two red quantum dots 31R and the region (space) K between them, as shown in Figure 5. Specifically, schematic diagrams F1, F2, and F3 show pair P1, P2, and P3, which are examples of pairs of red quantum dots 31X and red quantum dots 31Y, respectively.

[0041] In this specification, when we say that a member fills the space between multiple red quantum dots 31R, it is sufficient to understand that the member fills at least the region K between red quantum dots 31X and red quantum dots 31Y, as shown in schematic diagram F1 of set P1 in Figure 6. Region K is the region enclosed in the cross-section of the red light-emitting layer 23R by two lines (common outer tangents) tangent to the outer circumferences of red quantum dots 31X and red quantum dots 31Y, and by the opposing outer circumferences of red quantum dots 31X and red quantum dots 31Y. Therefore, as shown in schematic diagram F2 of set P2 in Figure 6, region K can exist even when red quantum dots 31X and red quantum dots 31Y are close to each other, and the member fills this region K.

[0042] That the member fills the space between a plurality of red quantum dots 31R does not necessarily mean that the entire region K between the red quantum dot 31X and the red quantum dot 31Y consists only of the member. For example, as shown in schematic diagram F1 and schematic diagram F2, the porous part 42 of the inorganic matrix 41 may be included in the region K. Further, the photosensitive material 51 may fill at least a part of the porous part 42. Here, in a cross-section passing through two red quantum dots 31R and the region K between the two red quantum dots 31R, assume that the maximum diameter of the porous part 42 located in the region K is 20 nm or less and the inorganic matrix 41 fills the region K excluding the porous part 42. In this case, the inorganic matrix 41 may be regarded as filling the region K. Also, as shown in the schematic diagram F1 of FIG. 6, the porous part 42 located in the region K may cover the entire periphery thereof with respect to the region K. On the other hand, as shown in the schematic diagram F2 of FIG. 6, the porous part 42 located in the region K may cover only a part of the periphery thereof with respect to the region K.

[0043] Further, as shown in the schematic diagram F3, cracks 43 of the inorganic matrix 41 may be included in the region K. Also, the photosensitive material 51 may fill at least a part of the cracks 43. Here, in a cross-section passing through two red quantum dots 31R and the region K between the two red quantum dots 31R, assume that the maximum width of the cracks 43 on the outermost surface of the region K is 20 nm or less and the inorganic matrix 41 fills the region K excluding the cracks 43. Alternatively, in the above cross-section, assume that the maximum depth of the cracks 43 from the outermost surface of the region K is 40 nm or less and the inorganic matrix 41 fills the region K excluding the cracks 43. In this case, the inorganic matrix 41 may be regarded as filling the region K. Also, in the above cross-section, if it is confirmed that the inorganic matrix 41 is located in 50% or more of the total area of the region K, the inorganic matrix 41 may be regarded as filling the region K.

[0044] Returning to the references in Figures 1 and 5, the inorganic matrix 41 may surround at least one red quantum dot 31R. In this disclosure, if the inorganic matrix 41 is located in more than 90% of the periphery of the red quantum dot 31R in a cross-section of the red light-emitting layer 23R passing through the red quantum dot 31R, the red quantum dot 31R may be considered to be covered by the inorganic matrix 41. The inorganic matrix 41 may also be in contact with the surface of the red quantum dot 31R. Furthermore, the inorganic matrix 41 may be located at any position in the film thickness direction DT of the red light-emitting layer 23R, with a distance of 1000 nm in the planar direction DP of the light-emitting layer 23. ２ It may have a continuous film with the above area.

[0045] <Functions of the Inorganic Matrix and Photosensitive Material> The red light-emitting layer 23R according to this embodiment comprises red quantum dots 31R and an inorganic matrix 41 filling the space between at least two red quantum dots 31R. Therefore, the red light-emitting layer 23R can reduce the degradation of the red quantum dots 31R due to the penetration of foreign substances such as oxygen or moisture into the red quantum dots 31R or the conduction of heat into the red quantum dots 31R. In particular, the inorganic matrix 41 surrounding the red quantum dots 31R further reduces the degradation of the red quantum dots 31R.

[0046] Furthermore, the red light-emitting layer 23R is equipped with a photosensitive material 51. This improves the overall density of the red light-emitting layer 23R and enhances its mechanical strength, for example, by having the photosensitive material 51 fill the voids around the red quantum dots 31R.

[0047] Therefore, the red light-emitting element 2R according to this embodiment improves reliability by reducing the degradation of the red quantum dots 31R in the red light-emitting layer 23R while improving the mechanical strength of the red light-emitting layer 23R. The display device 1 equipped with the red light-emitting element 2R achieves a longer lifespan.

[0048] In particular, in this embodiment, the photosensitive material 51 fills at least a portion of at least one of the porosity 42 and crack 43 of the inorganic matrix 41. As a result, the photosensitive material 51 more efficiently fills the voids in the red light-emitting layer 23R of the red light-emitting element 2R, thereby improving its mechanical strength.

[0049] Referring to Figure 1, in this embodiment, the green light-emitting layer 23G has the same configuration as the red light-emitting layer 23R, except that it includes green quantum dots 31G that emit green light instead of red quantum dots 31R. Similarly, the blue light-emitting layer 23B has the same configuration as the red light-emitting layer 23R, except that it includes blue quantum dots 31B that emit blue light instead of red quantum dots 31R.

[0050] In other words, the green light-emitting layer 23G includes green quantum dots 31G, an inorganic matrix 41 filling the spaces between at least two green quantum dots 31G, and a photosensitive material 51. The blue light-emitting layer 23B also includes blue quantum dots 31B, an inorganic matrix 41 filling the spaces between at least two blue quantum dots 31B, and a photosensitive material 51.

[0051] Therefore, for the same reasons as described above, the green light-emitting element 2G and the blue light-emitting element 2B improve reliability by reducing the degradation of quantum dots in their respective light-emitting layers while improving the mechanical strength of the light-emitting layers.

[0052] Furthermore, in this embodiment, an example has been described in which the light-emitting layer of each light-emitting element includes an inorganic matrix 41 filling the space between at least two quantum dots and a photosensitive material 51, but the embodiment is not limited to this. For example, each light-emitting element according to this embodiment may include an inorganic matrix 41 filling the space between at least two hole transport materials and a photosensitive material 51 in the hole transport layer 22. In this case, the light-emitting element improves the mechanical strength of the hole transport layer 22 while reducing the degradation of the hole transport material in the hole transport layer 22. Also, each light-emitting element according to this embodiment may include an inorganic matrix 41 filling the space between at least two electron transport materials and a photosensitive material 51 in the electron transport layer 24. In this case, the light-emitting element improves the mechanical strength of the electron transport layer 24 while reducing the degradation of the electron transport material in the electron transport layer 24.

[0053] <Examples of materials for the inorganic matrix> The inorganic matrix 41 may contain at least one of a metal oxide and a metal sulfide. With the above configuration, each light-emitting device has a denser inorganic matrix 41 and improves the protective effect of the inorganic matrix 41 on the quantum dots. In particular, the inorganic matrix 41 may have an insulator. This further improves the protective effect of the inorganic matrix 41 on the quantum dots in each light-emitting device. In this disclosure, the metal atoms contained in the metal oxide of the inorganic matrix 41 may be atoms that are generally referred to as metalloid atoms, including silicon (Si), boron (B), germanium (Ge), arsenic (As), antimony (Sb), and tellurium (Te).

[0054] For example, the inorganic matrix 41 may include at least one from the group consisting of silicon oxide, boron oxide, phosphorus oxide, germanium oxide, beryllium fluoride, arsenic sulfide, silicon selenide, germanium sulfide, titanium oxide, tellurium oxide, aluminum oxide, bismuth oxide, vanadium oxide, antimony oxide, lead oxide, silicon nitride, and magnesium oxide. With the above configuration, each light-emitting device has a more densely constructed inorganic matrix 41, improving the protection effect of the quantum dots by the inorganic matrix 41.

[0055] The inorganic matrix 41 may also contain halogen atoms. The inorganic matrix 41 may contain, for example, a halide or a halogen element. In this disclosure, “atom” does not mean only to exist as a single atom. In this disclosure, “atom” includes those that exist in the form of a molecule having two or more atoms, including the atom in question and another atom, those that exist in the form of a complex, those that exist in the form of a compound, or those that exist in the form of an ion. In this disclosure, “atom” does not limit the other forms of existence of an atom. That is, a halogen atom includes those that exist in the form of a compound containing a halogen atom, and those that exist in the form of a halogen ion. Regardless of the form of existence, if the presence of a halogen atom can be identified in the substance by analysis, the substance may be considered to contain a halogen atom.

[0056] As described later, the inorganic matrix 41 can be formed by transforming the precursor in a dispersion containing quantum dots and the precursor. When forming the inorganic matrix 41 from the precursor, gaps may form between the quantum dots, resulting in defects on the surface of the quantum dots that are not covered by the inorganic matrix 41. Therefore, by mixing a material containing halogen atoms into the dispersion, the halogen atoms can coat the surface of the quantum dots independently of the inorganic matrix 41, thereby reducing defects on the surface of the quantum dots. Consequently, the presence of halogen atoms in the inorganic matrix 41 increases the coverage of the quantum dots in the light-emitting layer of each light-emitting device, thereby improving its light-emitting properties.

[0057] <Examples of photosensitive material> The photosensitive material 51 may be a photoresist whose solubility in a specific solvent changes when irradiated with light such as ultraviolet light. In this case, as will be described later, the photosensitive material 51 included in the light-emitting layer 23 can be the same as the photoresist used for patterning the light-emitting layer 23. Therefore, with the above configuration, each light-emitting device can reduce manufacturing costs or simplify the process of forming the light-emitting layer 23.

[0058] For example, in this embodiment, the photosensitive material 51 is a positive-type photoresist that acquires solubility in a specific solvent by irradiation with light. In this case, as will be described later, the patterning of the light-emitting layer 23 can be performed more simply in the manufacturing method of the display device 1, or the accuracy of the formation position of the light-emitting layer 23 can be further improved.

[0059] However, in the present disclosure, the photosensitive material 51 is not limited to this, and may be a negative photoresist that acquires poor solubility in a specific solvent by irradiation with light. In this case, even when the photosensitive material 51 is denatured by light from each quantum dot or light from outside the display device 1, the light-emitting layer 23 can reduce deterioration such as dissolution of the photosensitive material 51 in the surroundings. In particular, the photosensitive material 51 may be a negative photoresist that acquires poor solubility in a solvent such as a developer by forming a crosslinked structure upon exposure. In this case, the photosensitive material 51 filling the porous 42 or the crack 43 forms a crosslinked structure by light from each quantum dot or light from outside the display device 1, and further improves the mechanical strength of the light-emitting layer 23.

[0060] When the photosensitive material 51 is a photoresist, the photoresist may contain at least one of a group including DQN (diazonaphthoquinone) and a bisazide compound. Further, the photosensitive material 51 may contain a photoinitiator that serves as a catalyst for denaturation of the exposed photoresist. For example, the photosensitive material 51 may contain a photo radical generator as the photoinitiator. In this case, the photosensitive material 51 may contain at least one of a group including a benzophenone-based compound, an acetophenone-based compound, a benzoin ether-based compound, and a thioxanthone-based compound. Further, the photosensitive material 51 may contain a photo cation generator as the photoinitiator. In this case, the photosensitive material 51 may contain at least one of a group including an iodonium salt-based compound and a sulfonium salt-based compound. Furthermore, the photosensitive material 51 may contain a photo anion generator as the photoinitiator. In this case, the photosensitive material 51 may contain at least one of a group including a primary to tertiary amine-based compound, an amidine-based compound, and a guanidine-based compound. These photoresists can be easily used for patterning the light-emitting layer 23.

[0061] In particular, the photosensitive material 51 may contain DQN represented by the following chemical formula (1). Note that R １ and R ２ each is hydrogen or a monovalent functional group.

[0062] Here, when DNQ is exposed to light, for example by absorbing light from a light-emitting material such as a red quantum dot 31R, or light from outside the display device 1, it converts diazoketone to nitrogen (N). ２ A Wolff rearrangement occurs in which the ) detaches and rearranges into ketene. For example, in the Wolff rearrangement of DNQ, polarization by photosensitization or the like first causes it to change to the structure of chemical formula (2) below.

[0063] Next, when the material having the structure of chemical formula (2) is further exposed to light, nitrogen is released and it changes to the structure of chemical formula (3) below, which contains a carbene.

[0064] Furthermore, the structure shown in chemical formula (3) undergoes a 1,2 rearrangement by the carbene to the structure shown in chemical formula (4) below.

[0065] A material having the structure shown in chemical formula (4) contains water (H ２ Upon contact with O), it absorbs the moisture and changes to the structure shown in the following chemical formula (5).

[0066] The material having the structure shown in chemical formula (5) is stable, and moisture does not easily escape from it. Therefore, the photosensitive material 51 having DNQ absorbs moisture that penetrates from outside the red light-emitting layer 23R toward the red quantum dots 31R, thereby reducing contact between the red quantum dots 31R and moisture, and improving the reliability of the red light-emitting layer 23R.

[0067] In this embodiment, the inorganic matrix 41 and the photosensitive material 51 may be made of the same material regardless of the emission color of the subpixel, but are not limited thereto. For example, the inorganic matrix 41 and the photosensitive material 51 may contain appropriate materials depending on the band gap of the quantum dots contained in the emission layer of each subpixel. In other words, each of two light-emitting elements with different emission colors may contain an inorganic matrix 41 and a photosensitive material 51 made of different materials.

[0068] The method for manufacturing the display device 1 according to this embodiment will be described with reference to Figure 7. Figure 7 is a flowchart of the method for manufacturing the display device 1 according to this embodiment.

[0069] In the manufacturing method of the display device 1 according to this embodiment, first, a substrate 3 is prepared (step S1). The substrate 3 may be formed by forming a pixel circuit and a driver for driving the light-emitting element 2 of each subpixel on a substrate such as a glass substrate or a film substrate.

[0070] Next, an anode 21 is formed on the substrate 3 (step S2). The anode 21 may be formed by forming a thin film of a conductive material common to multiple subpixels using the method described above, and then patterning the thin film for each subpixel. In step S2, regarding the patterning of the anode 21, a bank BK may be formed between each adjacent anode 21. Next, a hole transport layer 22 is formed on the anode 21 using the method described above (step S3). The hole transport layer 22 may be formed common to multiple subpixels, or it may be patterned for each subpixel. Between the formation of the anode 21 and the formation of the hole transport layer 22, a hole injection layer may be formed on the anode 21 using the same method as the formation of the hole transport layer 22, except for the material. In this case, the hole transport layer 22 may be formed on the hole injection layer.

[0071] <Manufacturing Method for Display Device: Formation of Light-Emitting Layer: Overview> Next, a light-emitting layer 23 is formed on the hole transport layer 22 (step S4). The method for forming the light-emitting layer 23 will be described in more detail with reference to Figures 8 to 16. Figure 8 is a flowchart of the method for forming the light-emitting layer 23 according to this embodiment. Figures 9 to 16 are cross-sectional views of the process side of the method for forming the light-emitting layer 23 according to this embodiment, and in particular show cross-sections corresponding to the cross-section shown in Figure 3. Hereafter, in order to simplify the explanation of the structure of the illustrated display device 1, each cross-sectional view of the process side in this disclosure will be a cross-sectional view of the process side when manufacturing the display device 1 according to the modified example 1 shown in Figure 3. However, this embodiment is not limited to this, and the display device 1 shown in Figure 1 or the display device 1 shown in Figure 4 may be manufactured by controlling the formation position of each layer as described later.

[0072] In this embodiment, step S4 is repeated as many times as the number of light-emitting colors of the subpixels of the display device 1, in other words, the number of types of light emitted by the light-emitting layer 23. In this embodiment, the display device 1 has subpixels of three light-emitting colors: red subpixel XR, green subpixel XG, and blue subpixel XB, so step S4 is repeated three times. In this embodiment, a method of forming the red light-emitting layer 23R, the green light-emitting layer 23G, and the blue light-emitting layer 23B in this order by repeating step S4 three times will be described as an example.

[0073] <Manufacturing method for display device: Formation of light-emitting layer: Formation of photosensitive layer> At the completion of step S3, as shown in step S3 of Figure 9, an anode 21, a bank BK, and a hole transport layer 22 are formed on the substrate 3. In the method for forming the red light-emitting layer 23R in step S4, first, as shown in step S41-1 of Figure 9, a photosensitive layer 61 is formed (step S41). The photosensitive layer 61 contains a photosensitive material 51. The photosensitive layer 61 may be formed by coating the photosensitive material 51 onto the hole transport layer 22 using a coating method including, for example, a conventionally known method such as a slit coating method or a spin coating method.

[0074] Next, a portion of the photosensitive material layer 61 is exposed (step S42). For example, in step S42 of the method for forming the red light-emitting layer 23R, as shown in step S42-1 of Figure 10, a photomask MR having light-transmitting portions such as openings for the red subpixels XR in a plan view of the substrate 3 is placed above the photosensitive material layer 61. Then, light such as ultraviolet light is irradiated from the side of the photomask MR on the substrate 3. As a result, a photosensitive material layer 62 is formed in which the photosensitive material 51 in the portion of the photosensitive material layer 61 that overlaps with the red subpixels XR in a plan view of the substrate 3 is transformed into the exposed photosensitive material 52.

[0075] Next, a portion of the photosensitive material layer 62 is removed (step S43). The removal of a portion of the photosensitive material layer 62 may be performed by washing the photosensitive material layer 62, which contains the exposed photosensitive material 52, with a suitable developer. When the photosensitive material 51 is a positive-type photoresist, the unexposed photosensitive material 51 is poorly soluble in the developer, while the exposed photosensitive material 52 gains solubility in the developer. Therefore, by washing the photosensitive material layer 62 with a developer, for example, in step S42 of the method for forming the red light-emitting layer 23R, only the photosensitive material 52 located in the red subpixel XR is removed, as shown in step S43-1 of Figure 10. Thus, in step S42, a photosensitive material layer 63 is formed that contains the unexposed photosensitive material 51 remaining in the green subpixel XG and the blue subpixel XB.

[0076] When the photosensitive material 51 is a positive-type photoresist, the position control of the photosensitive material 52 to be removed in step S42 becomes easier compared to when the photosensitive material 51 is a negative-type photoresist. Therefore, the photosensitive material 51 containing a positive-type photoresist simplifies the method of forming the light-emitting layer 23, or improves the accuracy of the formation position of the light-emitting layer 23.

[0077] <Manufacturing method for display device: Formation of light-emitting layer: Application of quantum dot dispersion> Next, the quantum dot dispersion is applied (step S44). In particular, in step S44 of the method for forming the red light-emitting layer 23R, as shown in step S44-1 of Figure 11, the red quantum dot dispersion 71R is applied to the remaining photosensitive layer 63 and the hole transport layer 22 exposed from the photosensitive layer 63. The red quantum dot dispersion 71R is a dispersion in which red quantum dots 31R and precursors 73 of the inorganic matrix 41 are dispersed in a solvent 72.

[0078] The precursor 73 includes a material that is converted into the inorganic matrix 41 through hydrolysis and dehydration condensation by performing a specific operation such as heating or light irradiation. For example, if the inorganic matrix 41 contains silicon oxide, the precursor 73 may also contain tetramethyl orthosilicate (TMOS) shown in formula (6) below.

[0079] Furthermore, if the inorganic matrix 41 contains silicon oxide, for example, the precursor 73 may contain 3-(mercaptopropyl)trimethoxysilane (MPS) as shown in formula (7) below.

[0080] The red quantum dot dispersion 71R contains zinc chloride (ZnCl) as a halogenated halide. ２ ) may be included.

[0081] The red quantum dot dispersion 71R may be prepared, for example, by stirring a dispersion containing red quantum dots 31R and a dispersion containing precursor 73 to prepare a mixture, and then extracting the intermediate layer of the mixture. Here, the dispersion containing red quantum dots 31R may contain an organic ligand that coordinates to the red quantum dots 31R. In this case, for example, during stirring for the preparation of the mixture, the ligand that coordinates to the red quantum dots 31R may be replaced from the organic ligand to a part of the precursor 73 such as MPS.

[0082] <Manufacturing method for display device: Formation of light-emitting layer: Conversion of precursor> Following the application of the quantum dot dispersion, the precursor 73 is converted into an inorganic matrix 41 (step S45). In particular, in step S45 of the method for forming the red light-emitting layer 23R, the solvent 72 is volatilized by heating the applied red quantum dot dispersion 71R, and the precursor 73 is converted into an inorganic matrix 41. For example, if the precursor 73 contains TMOS and MPS, dehydration condensation occurs between TMOS molecules, between MPS molecules, and between TMOS and MPS, etc., to form silicon oxide as the inorganic matrix 41. The conversion of the precursor 73 into the inorganic matrix 41 occurs sequentially around the red quantum dots 31R of the red quantum dot dispersion 71R.

[0083] Therefore, as shown in step S45-1 of Figure 11, a red quantum dot layer 74R is formed in step S45 of the method for forming the red light-emitting layer 23R. The red quantum dot layer 74R comprises a plurality of red quantum dots 31R and an inorganic matrix 41 filling the spaces between the plurality of red quantum dots 31R. Of the red quantum dot layer 74R, the portion located at the red subpixel XR is located on the hole transport layer 22, and the portions located at the green subpixel XG and blue subpixel XB are located on the photosensitive material layer 63.

[0084] In the conversion from the precursor 73 to the inorganic matrix 41, multiple voids containing porous material 42 may be formed in the inorganic matrix 41 due to outgassing from the precursor 73 or volume contraction of the red quantum dot dispersion 71R. Furthermore, in the above conversion, cracks 43, which are not shown in step S45-1 of Figure 11, may be formed in the inorganic matrix 41 due to the generation of stress in the inorganic matrix 41 caused by volume contraction of the red quantum dot dispersion 71R.

[0085] Furthermore, the side surface of the red quantum dot layer 74R located at the red subpixel XR is in contact with the photosensitive material layer 63, and the underside of the red quantum dot layer 74R located at the green subpixel XG and blue subpixel XB is in contact with the photosensitive material layer 63. For this reason, the photosensitive material 51 in the photosensitive material layer 63 may penetrate at least some of the pores 42 or cracks 43 in the inorganic matrix 41 of the red quantum dot layer 74R. In other words, in step S45, the photosensitive material 51 may fill at least some of the pores 42 and cracks 43 of the red quantum dot layer 74R. As a result, a quantum dot layer containing the photosensitive material 51 is formed in step S45.

[0086] <Manufacturing method for display device: Formation of light-emitting layer: Patterning of quantum dot layer> Next, the quantum dot layer is patterned (step S46). In this embodiment, the patterning of the quantum dot layer is performed by a lift-off method by removing the photosensitive material layer remaining on the hole transport layer 22. In particular, in step S46 of the method for forming the red light-emitting layer 23R, the photosensitive material layer 63 is removed together with the red quantum dot layer 74R located on the photosensitive material layer 63 by washing the photosensitive material layer 63 with a cleaning solution that also dissolves the unexposed photosensitive material 51. As a result, as shown in step S46-1 of Figure 12, only the portion of the red quantum dot layer 74R located at the red subpixel XR remains on the hole transport layer 22, and the red light-emitting layer 23R is formed.

[0087] In step S46 of the method for forming the red light-emitting layer 23R, the photosensitive material 51 in the photosensitive material layer 63 dissolves in the cleaning solution, and the red quantum dot layer 74R on the hole transport layer 22 is exposed to the cleaning solution. As a result, the photosensitive material 51 in the cleaning solution may penetrate into the pores 42 or cracks 43 in the inorganic matrix 41 of the red quantum dot layer 74R. Therefore, in step S46 of the method for forming the red light-emitting layer 23R, as shown in step S46-1 of Figure 12, the photosensitive material 51 may fill at least a portion of the pores 42 and cracks 43 of at least a portion of the red light-emitting layer 23R. In this embodiment, as shown in step S46-1 of Figure 12, the photosensitive material 51 fills all of the pores 42 and cracks 43 in the inorganic matrix 41 of the red light-emitting layer 23R, but is not limited to this, and may fill only a portion of the pores 42 or cracks 43.

[0088] <Manufacturing Method for Display Device: Formation of Light-Emitting Layer: Formation of Light-Emitting Layers of Other Light-Emitting Colors> In this embodiment, the formation of the red light-emitting layer 23R is performed, and the formation of the green light-emitting layer 23G is performed. In forming the green light-emitting layer 23G, first, as shown in step S41-2 of Figure 12, a photosensitive material layer 64 containing a photosensitive material 51 is formed on the hole transport layer 22 and the red light-emitting layer 23R by the same method as in step S41 described above. Here, the side and top surfaces of the red light-emitting layer 23R are in contact with the photosensitive material layer 64 containing the photosensitive material 51. For this reason, in step S41 of the method for forming the green light-emitting layer 23G, the photosensitive material 51 in the photosensitive material layer 64 may fill at least a portion of the pores 42 and cracks 43 of at least a portion of the red light-emitting layer 23R. Furthermore, once the photosensitive material 51 has penetrated the porous material 42 or crack 43, it is strongly adsorbed to the porous material 42 or crack 43 by the capillary effect, making it difficult for the photosensitive material 51 to flow out to the outside of the photosensitive material layer 64 or the like again.

[0089] Next, a portion of the photosensitive material layer 64 is exposed using the same method as in step S42 described above. For example, in step S42 of the method for forming the green light-emitting layer 23G, as shown in step S42-2 of Figure 13, a photomask MG having light-transmitting portions such as openings for the green subpixels XG in a plan view of the substrate 3 is placed above the photosensitive material layer 64. Then, light such as ultraviolet light is irradiated from the side of the photomask MG on the substrate 3. As a result, a photosensitive material layer 65 is formed in which the photosensitive material 51 in the portion of the photosensitive material layer 64 that overlaps with the green subpixels XG in a plan view of the substrate 3 is transformed into exposed photosensitive material 52.

[0090] Next, using the same method as in step S43 described above, in other words, the photosensitive material layer 65 containing the exposed photosensitive material 52 is washed with an appropriate developer to remove a portion of the photosensitive material layer 65. As a result, in step S42 of the method for forming the green light-emitting layer 23G, as shown in step S43-2 of Figure 13, only the photosensitive material 52 located at the green subpixel XG is removed. Therefore, in step S42, a photosensitive material layer 66 is formed that contains the unexposed photosensitive material 51 remaining at the red subpixel XR and the blue subpixel XB.

[0091] Next, the quantum dot dispersion is applied using the same method as in step S44 described above. In particular, in step S44 of the method for forming the green light-emitting layer 23G, as shown in step S44-2 of Figure 14, the green quantum dot dispersion 71G is applied to the remaining photosensitive layer 66 and the hole transport layer 22 exposed from the photosensitive layer 65. The green quantum dot dispersion 71G may be the same as the red quantum dot dispersion 71R in that it contains green quantum dots 31G instead of red quantum dots 31R.

[0092] Next, the precursor 73 in the green quantum dot dispersion 71G is converted to the inorganic matrix 41 by the same method as in step S45 described above. As a result, as shown in step S45-2 of Figure 15, the green quantum dot layer 74G is formed in step S45 of the method for forming the green light-emitting layer 23G. The green quantum dot layer 74G comprises a plurality of green quantum dots 31G and an inorganic matrix 41 filling the spaces between the plurality of green quantum dots 31G. Of the green quantum dot layer 74G, the portion located at the green subpixel XG is located on the hole transport layer 22, and the portions located at the red subpixel XR and blue subpixel XB are located on the photosensitive material layer 66.

[0093] For the same reasons as described above, in step S45 of the method for forming the green light-emitting layer 23G, at least one of the porosity 42 and cracks 43 may be formed in the inorganic matrix 41 of the green quantum dot layer 74G. Furthermore, the photosensitive material 51 may fill at least a portion of the porosity 42 and cracks 43 of at least a portion of the green quantum dot layer 74G.

[0094] Next, the green quantum dot layer 74G is patterned by removing the remaining photosensitive layer 66 using the same method as in step S46 described above. As a result, as shown in step S46-2 of Figure 16, only the portion of the green quantum dot layer 74G located at the green subpixel XG remains on the hole transport layer 22, forming the green light-emitting layer 23G. For the same reasons as described above, in step S46 of the method for forming the green light-emitting layer 23G, the photosensitive material 51 in the cleaning solution may fill at least a portion of the pores 42 and cracks 43 of at least a portion of the green light-emitting layer 23G.

[0095] In this embodiment, the formation of the blue light-emitting layer 23B is performed in conjunction with the formation of the green light-emitting layer 23G. The formation of the blue light-emitting layer 23B may be performed in the same manner as the formation of the red light-emitting layer 23R or the green light-emitting layer 23G, except that the quantum dots in the quantum dot dispersion are blue quantum dots 31B and the blue light-emitting layer 23B is formed on the blue subpixel XB. As a result, the blue light-emitting layer 23B located on the blue subpixel XB is formed, as shown in step S46-3 of Figure 16. With this, the formation of the red light-emitting layer 23R, the green light-emitting layer 23G, and the blue light-emitting layer 23B is completed, and the formation of the light-emitting layer 23 is completed.

[0096] <Manufacturing method for display device: After formation of electron transport layer> Referring back to Figure 7, following the formation of the light-emitting layer 23, an electron transport layer 24 is formed on the light-emitting layer 23 by the method described above (step S5). The electron transport layer 24 may be formed in common for multiple subpixels, or it may be patterned for each subpixel. Alternatively, the electron transport layer 24 may be formed so as to partition the light-emitting layer 23 for each subpixel.

[0097] Next, the cathode 25 is formed (step S6). The cathode 25 may be formed by forming a thin conductive film common to multiple subpixels using the method described above. With this, the light-emitting element 2 is formed on the substrate 3, and the manufacturing of the display device 1 is completed. According to the above method, a light-emitting element 2 with improved reliability and mechanical strength of the light-emitting layer 23 can be manufactured.

[0098] Furthermore, in the method for forming the light-emitting element 2 according to this embodiment, the light-emitting layer 23 is formed by patterning a quantum dot layer using a photosensitive material layer containing a photosensitive material 51. Therefore, according to the above method, the porosity 42 or cracks 43 in the inorganic matrix 41 of the light-emitting layer 23 can be filled with the photosensitive material 51 in a simple manner by patterning the quantum dot layer.

[0099] <Notes on the manufacturing method of the display device> The display device 1 includes, for example, a red light-emitting element 2R as a first light-emitting element and a green light-emitting element 2G as a second light-emitting element. Therefore, in the manufacturing method of the display device 1, as described above, it is necessary to pattern at least the red light-emitting layer 23R of the red light-emitting element 2R and the green light-emitting layer 23G of the green light-emitting element 2G. As described above, the display device 1 makes it possible to form the photosensitive material 51 that fills the porosity 42 or cracks 43 of the inorganic matrix 41 more simply in the patterning of the quantum dot layer in the formation process of the light-emitting layer 23.

[0100] In the method for forming the light-emitting element 2 according to this embodiment, the hole transport layer 22 or the electron transport layer 24 is not limited to the method described above. For example, the hole transport layer 22 may be formed to include an inorganic matrix 41 filling the spaces between a plurality of hole transport materials and a photosensitive material 51 filling at least a portion of the pores 42 and cracks 43 of the inorganic matrix 41. Similarly, the electron transport layer 24 may be formed to include an inorganic matrix 41 filling the spaces between a plurality of electron transport materials and a photosensitive material 51 filling at least a portion of the pores 42 and cracks 43 of the inorganic matrix 41.

[0101] In other words, in the method for forming the light-emitting element 2 according to this embodiment, the formation of at least one functional layer includes a plurality of functional materials, an inorganic matrix 41 filling the spaces between the plurality of functional materials, and a photosensitive material 51. This method improves the reliability and mechanical strength of the functional layer.

[0102] The hole transport layer 22 or electron transport layer 24, which includes an inorganic matrix 41 and a photosensitive material 51, may be formed by the same method as the above-described method for forming the light-emitting layer 23, except that the quantum dots are replaced with hole transport material or electron transport material. In this case, the formation of the hole transport layer 22 or electron transport layer 24 does not necessarily include a patterning step for the layer containing the hole transport material or electron transport material and the inorganic matrix 41. In other words, in the formation of the hole transport layer 22 or electron transport layer 24, steps S41 to S43 and S46 described above do not need to be performed. However, in the formation of the hole transport layer 22 or electron transport layer 24, a solution containing the photosensitive material 51 may be dropped or coated onto the layer containing the hole transport material or electron transport material and the inorganic matrix 41. This allows the photosensitive material 51 to penetrate at least a portion of the pores 42 and cracks 43 of the inorganic matrix 41.

[0103] <Other Examples of Light-Emitting Layers> Referring to Figures 17 to 19, other examples of the structure of the light-emitting layer 23 according to this embodiment will be described by giving other examples of the red light-emitting layer 23R. Figures 17 to 19 are other examples of schematic side cross-sectional views of the light-emitting layer 23 according to this embodiment, and in particular show other examples of schematic side cross-sectional views of the red light-emitting layer 23R. However, in this embodiment, the green light-emitting layer 23G and the blue light-emitting layer 23B may each have the same configuration as any of the red light-emitting layers 23R shown in Figures 17 to 19, except for the emission color of the quantum dots.

[0104] The red light-emitting element 2R may have a red light-emitting layer 23RA as shown in Figure 17 instead of the red light-emitting layer 23R. The red light-emitting layer 23RA differs in its structure from the red light-emitting layer 23R in that the inorganic matrix 41 comprises at least one of the porous 44 and the cracks 45. The photosensitive material 51 fills only a portion of the porous 44 or only a portion of the cracks 45. Therefore, voids may be present in the porous 44 and the cracks 45.

[0105] The voids in the porous 44 and crack 45 may contain an inert gas such as nitrogen, residue of the solvent used in the formation of the red light-emitting layer 23RA or volatile gases of the solvent, or an organic ligand. The photosensitive material 51 filling a portion of the porous 44 may also fill a portion of the surrounding wall of the porous 44. The photosensitive material 51 filling a portion of the crack 45 may also fill a portion of the central side of the red light-emitting layer 23RA of the crack 45.

[0106] The red light-emitting element 2R may, instead of the red light-emitting layer 23R, comprise the red light-emitting layers 23RB, 23RC, 23RD, 23RE, or 23RF shown in Figures 17 to 19, respectively. Each of the red light-emitting layers 23RB, 23RC, 23RD, 23RE, and 23RF differs in configuration from the red light-emitting layer 23R in that the inorganic matrix 41 further comprises at least one of porous 46 and cracks 47.

[0107] The photosensitive material 51 is not located in the porous 46 and cracks 47. Therefore, the porous 46 and cracks 47 may be voids in the inorganic matrix 41. Inert gases such as nitrogen, residues of the solvent mentioned above or volatile gases of the solvent, or organic ligands may be located in the porous 46 and cracks 47.

[0108] As shown in Figure 17, the red light-emitting layer 23RB contains porosity 42 or cracks 43 only in the vicinity of the side surface in the planar direction DP and the top surface in the film thickness direction DT. The red light-emitting layer 23RB may also contain porosity 46 or cracks 47 on the central side in the planar direction DP and the central side in the film thickness direction DT or near the bottom surface.

[0109] As shown in Figure 18, the red light-emitting layer 23RC contains porosity 42 or cracks 43 only near the lower surface in the film thickness direction DT of the red light-emitting layer 23RC. The red light-emitting layer 23RC may also contain porosity 46 or cracks 47 near the center and upper surface in the film thickness direction DT of the red light-emitting layer 23RC.

[0110] As shown in Figure 18, the red light-emitting layer 23RD contains porosity 42 or cracks 43 only on the central side in the planar direction DP and near the lower surface in the film thickness direction DT. The red light-emitting layer 23RD may also contain porosity 46 or cracks 47 near the side surface in the planar direction DP, on the central side in the film thickness direction DT, and near the upper surface in the film thickness direction DT.

[0111] As shown in Figure 19, the red light-emitting layer 23RE contains porosity 42 or cracks 43 only on the central side in the film thickness direction DT of the red light-emitting layer 23RE. The red light-emitting layer 23RE may also contain porosity 46 or cracks 47 near the upper and lower surfaces in the film thickness direction DT of the red light-emitting layer 23RE.

[0112] As shown in Figure 19, the red light-emitting layer 23RF contains porosity 42 or cracks 43 only near the side surface in the planar direction DP of the red light-emitting layer 23RF. The red light-emitting layer 23RF may also contain porosity 46 or cracks 47 on the central side in the planar direction DP of the red light-emitting layer 23RF.

[0113] In the light-emitting layer 23 according to this embodiment, the filling of each pore or crack of the inorganic matrix 41 with the photosensitive material 51 may be controlled by changing the time during which the quantum dot layer and the photosensitive material 51 are in contact during the formation of the light-emitting layer 23. For example, a light-emitting layer 23 having pores 44 or cracks 45 may be formed by shortening the time during which the quantum dot layer and the photosensitive material 51 are in contact during the formation of the light-emitting layer 23 compared to a light-emitting layer 23 having pores 42 or cracks 43. In the process of forming the light-emitting layer 23, a process to add energy to the quantum dot layer may be performed, such as heating the quantum dot layer to which the photosensitive material 51 is coated, or vibrating the quantum dot layer with ultrasonic waves. In this embodiment, the filling rate of the photosensitive material 51 into each pore or crack can be controlled.

[0114] Furthermore, the position of the porosity 42 or crack 43 in the light-emitting layer 23 may be controlled by contacting the photosensitive material 51 with the portion of the quantum dot layer corresponding to the position where the porosity 42 or crack 43 is to be formed during the formation of the light-emitting layer 23. For example, when forming the porosity 42 or crack 43 on the lower surface of the light-emitting layer 23, a layer of the photosensitive material 51 may be formed prior to the formation of the quantum dot layer during the formation of the light-emitting layer 23, and the quantum dot layer may be formed on top of the layer of the photosensitive material 51. Alternatively, after forming the light-emitting layer 23 having the porosity 42 or crack 43, the light-emitting layer 23 may be washed with a suitable solvent to remove the photosensitive material 51 from a portion of the porosity 42 and crack 43. This may result in the formation of a light-emitting layer 23 having the porosity 46 or crack 47 in desired positions.

[0115] [Embodiment 2] Other embodiments of the present disclosure will be described below with reference to the drawings. In this disclosure, the members described in the above embodiments will not be described further.

[0116] <Light-emitting layer with varying film thickness> The display device 1 according to this embodiment has the same configuration as the display device 1 according to the previous embodiment, except for the configuration of the light-emitting layer 23. The configuration of the light-emitting layer 23 according to this embodiment will be described with reference to Figures 20 and 21, using the red light-emitting layer 23R as an example. Figure 20 is a schematic side cross-sectional view of the light-emitting layer 23 according to this embodiment, and in particular is a schematic side cross-sectional view of the red light-emitting layer 23R shown in Figure 20. Figure 21 is a schematic plan cross-sectional view of the light-emitting layer 23 according to this embodiment, and in particular is a cross-sectional view taken along the line A-A of the red light-emitting layer 23R shown in Figure 20.

[0117] The red light-emitting layer 23R according to this embodiment has a peripheral portion ER and a central portion CR. As shown in Figure 21, the peripheral portion ER is located on the edge side in a plan view of the red light-emitting layer 23R. The central portion CR is located closer to the center than the peripheral portion ER in a plan view of the red light-emitting layer 23R.

[0118] As shown in Figures 20 and 21, the inorganic matrix 41 located in the peripheral ER of the red light-emitting layer 23R has a porous 42 filled with photosensitive material 51. Therefore, the peripheral ER contains the photosensitive material 51. The inorganic matrix 41 located in the peripheral ER of the red light-emitting layer 23R may also have cracks 43 filled with photosensitive material 51, which are not shown in Figures 20 and 21. On the other hand, the inorganic matrix 41 located in the central CR of the red light-emitting layer 23R has a porous 46 or cracks 47 in which no photosensitive material 51 is located.

[0119] As shown in Figure 20, in the film thickness direction DT of the red light-emitting layer 23R, the red light-emitting layer 23R has a film thickness TE at the peripheral ER and a film thickness TC at the central CR. Film thickness TE is greater than film thickness TC. In other words, in the red light-emitting layer 23R, the film thickness at the peripheral ER is greater than the film thickness at the central CR.

[0120] Except as described above, the red light-emitting layer 23R according to this embodiment has the same configuration as the red light-emitting layer 23R according to the previous embodiment.

[0121] As described above, in the formation of the red light-emitting layer 23R, the conversion of the precursor 73 to the inorganic matrix 41 may result in a reduction in the volume of the red quantum dot layer 74R. On the other hand, if the photosensitive material 51 penetrates into the pores 42 or cracks 43 of the inorganic matrix 41, the reduction in volume of the red quantum dot layer 74R near the pores 42 or cracks 43 is reduced. Therefore, if the location of the pores 42 or cracks 43 is limited to the peripheral ER in the formation of the red light-emitting layer 23R, it is possible to increase the volume of the peripheral ER compared to the central CR.

[0122] In the formation of the red light-emitting layer 23R, the red quantum dot layer 74R is patterned, so even if the peripheral ER lengthens along the planar direction DP of the red light-emitting layer 23R, the dimensions of the peripheral ER along the planar direction DP do not change. Therefore, due to the increase in volume at the peripheral ER of the red light-emitting layer 23R, the film thickness of the peripheral ER becomes larger than that of the central CR. Thus, by limiting the location of the porosity 42 or crack 43 to the peripheral ER during the formation of the red light-emitting layer 23R, it is possible to form a red light-emitting layer 23R having a peripheral ER with a larger film thickness compared to the film thickness of the central CR.

[0123] Because the film thickness of the peripheral ER is greater than the film thickness of the central CR, the red light-emitting element 2R can increase the mechanical strength of the red light-emitting layer 23R in the peripheral ER compared to the central CR. As a result, the red light-emitting element 2R reduces film peeling in the peripheral ER of the red light-emitting layer 23R and more effectively increases the mechanical strength of the red light-emitting layer 23R.

[0124] By positioning the photosensitive material 51 at the peripheral ER, the red light-emitting element 2R can increase the film thickness at the peripheral ER of the red light-emitting layer 23R with a simpler configuration. Furthermore, if the photosensitive material 51 contains a material that can absorb moisture, such as the DNQ described above, the red light-emitting element 2R can more efficiently protect the red quantum dots 31R from moisture that has penetrated from the peripheral ER side of the red light-emitting layer 23R.

[0125] In this embodiment as well, the green light-emitting layer 23G and the blue light-emitting layer 23B may each have the same configuration as the red light-emitting layer 23R shown in Figures 20 and 21, except for the light-emitting color of the quantum dots. In this case, the green light-emitting element 2G and the blue light-emitting element 2B each more effectively increase the mechanical strength of the green light-emitting layer 23G and the blue light-emitting layer 23B, respectively.

[0126] [Embodiment 3] <Mixing Section> The display device 1 according to this embodiment has the same configuration as the display device 1 according to any of the above embodiments, except for the configuration of the light-emitting layer 23. The configuration of the light-emitting layer 23 according to this embodiment will be described with reference to Figure 22, using the red light-emitting layer 23R as an example. Figure 22 is a schematic side cross-sectional view of the light-emitting layer 23 according to this embodiment, and in particular is a schematic side cross-sectional view of the red light-emitting layer 23R.

[0127] In this embodiment, the red light-emitting layer 23R includes a mixed portion 81 in its peripheral region ER, filling the spaces between the multiple red quantum dots 31R, instead of the inorganic matrix 41 and the photosensitive material 51. The mixed portion 81 is a mixture of the inorganic matrix 41 and the photosensitive material 51. Therefore, even in the peripheral region ER of the red light-emitting layer 23R in this embodiment, the inorganic matrix 41 can be considered to fill the spaces between the multiple red quantum dots 31R, and the peripheral region ER of the red light-emitting layer 23R includes the photosensitive material 51. In other words, in the peripheral region ER of the red light-emitting layer 23R, the inorganic matrix 41 and the photosensitive material 51 are mixed around the red quantum dots 31R, which are the functional materials of the red light-emitting layer 23R.

[0128] Except as described above, the red light-emitting layer 23R according to this embodiment has the same configuration as the red light-emitting layer 23R according to the previous embodiment.

[0129] As described above, immediately after coating the red quantum dot dispersion 71R in the formation of the red light-emitting layer 23R, the red quantum dot dispersion 71R comes into contact with the photosensitive material layer 63 containing the photosensitive material 51. Therefore, the photosensitive material 51 in the photosensitive material layer 63 may dissolve in the red quantum dot dispersion 71R. In particular, immediately after coating the red quantum dot dispersion 71R, the edge side of the red quantum dot dispersion 71R located at the red subpixel XR is in contact with the photosensitive material layer 63 in a plan view.

[0130] Therefore, the edge side of the red quantum dot dispersion 71R in a plan view may contain a mixture of the photosensitive material 51 and the precursor 73. In this state, by performing the conversion of the precursor 73 to the inorganic matrix 41, a mixed portion 81 is formed at the edge side of the red quantum dot layer 74R located at the red subpixel XR in a plan view, where the inorganic matrix 41 and the photosensitive material 51 are mixed.

[0131] In the mixing section 81, the voids such as porosity or cracks in the inorganic matrix 41 are reduced, improving density and, consequently, mechanical strength. Therefore, the red light-emitting element 2R further improves the mechanical strength of the red light-emitting layer 23R. In addition, the mixing section 81 can improve the refractive index while reducing the decrease in light transmittance. Therefore, the red light-emitting element 2R improves the straight-line propagation of light from the red light-emitting layer 23R, and consequently improves the efficiency of light extraction from the red light-emitting layer 23R. Furthermore, when the mixing section 81 is located in the peripheral section ER, the mixing section 81 improves insulation from other adjacent components. Therefore, the red light-emitting element 2R reduces short circuits between the red light-emitting layer 23R and the components surrounding the red light-emitting layer 23R, improving the luminous efficiency of the red light-emitting layer 23R.

[0132] In this embodiment as well, the green light-emitting layer 23G and the blue light-emitting layer 23B may each have the same configuration as the red light-emitting layer 23R shown in Figure 22, except for the light emission color of the quantum dots. In this case, the green light-emitting element 2G and the blue light-emitting element 2B each more effectively increase the mechanical strength of the green light-emitting layer 23G and the blue light-emitting layer 23B, respectively.

[0133] Furthermore, the hole transport layer 22 and the electron transport layer 24 may each have the same configuration as the red light-emitting layer 23R shown in Figure 22, except that they each contain a hole transport material and an electron transport material instead of the red quantum dots 31R. In this case, the light-emitting element 2 more effectively increases the mechanical strength of the hole transport layer 22 and the electron transport layer 24, respectively.

[0134] [Embodiment 4] <Emitting Region and Non-Emitting Region> The display device 1 according to this embodiment has the same configuration as the display device 1 according to any of the above embodiments, except for the configuration of the light-emitting layer 23. The configuration of the light-emitting layer 23 according to this embodiment will be described with reference to Figures 23 and 24, with the red light-emitting layer 23R as an example. Figure 23 is a schematic side cross-sectional view of the light-emitting layer 23 according to this embodiment, and in particular is a schematic side cross-sectional view of the red light-emitting layer 23R shown in Figure 23. Figure 24 is a schematic plan cross-sectional view of the light-emitting layer 23 according to this embodiment, and in particular is a cross-sectional view taken along the line B-B of the red light-emitting layer 23R shown in Figure 23.

[0135] The red light-emitting layer 23R according to this embodiment has a non-light-emitting region NR and a light-emitting region LR. As shown in Figure 24, the non-light-emitting region NR may be located towards the edge in a plan view of the red light-emitting layer 23R. The light-emitting region LR may be located closer to the center than the non-light-emitting region NR in a plan view of the red light-emitting layer 23R.

[0136] As shown in Figures 23 and 24, some of the red quantum dots 31R located in the non-emitting region NR of the red light-emitting layer 23R are deactivated red quantum dots 32R. Red quantum dots 32R are deactivated red quantum dots 31R. In particular, the emission intensity of red quantum dots 32R is lower than that of red quantum dots 31R when the same concentration of excitons is generated inside. For example, when the same concentration of excitons is generated inside, the emission intensity of red quantum dots 32R is more than 10% lower than that of red quantum dots 31R.

[0137] In this embodiment, for example, the inorganic matrix 41 located in the non-emitting region NR of the red light-emitting layer 23R has at least one of a porous 42 and a crack 43, at least a portion of which is filled with the photosensitive material 51. On the other hand, the inorganic matrix 41 located in the light-emitting region LR of the red light-emitting layer 23R has at least one of a porous 46 and a crack 47, in which the photosensitive material 51 is not located. Furthermore, the photosensitive material 51 filling the porous 42 or crack 43 of the non-emitting region NR may include the photoinitiator described above.

[0138] Except as described above, the red light-emitting layer 23R according to this embodiment has the same configuration as the red light-emitting layer 23R according to Embodiment 1.

[0139] The boundary between the non-emitting region NR and the emitting region LR of the red emitting layer 23R according to this embodiment may be confirmed by irradiating the red emitting layer 23R with light such as ultraviolet light to cause the red emitting layer 23R to emit light and measuring the emission intensity of each part. For example, in this confirmation, ultraviolet light of approximately the same intensity may be irradiated onto each part of the red emitting layer 23R to identify the first part, which is the part with the highest emission intensity. Then, the part where the difference in emission intensity with the first part is less than 10% may be considered the emitting region LR, and the part where the emission intensity is 10% or more lower than the emission intensity of the first part may be considered the non-emitting region NR.

[0140] For example, if the photosensitive material 51 contains a photoinitiator, exposure of the photosensitive material 51 generates photoradicals, photoacids, or photobases from the photoinitiator. Therefore, when the photosensitive material 51 is exposed, the red quantum dots 31R located near the photosensitive material 51 may be deactivated by the photoradicals, photoacids, or photobases generated from the photoinitiator of the photosensitive material 51, becoming red quantum dots 32R. For this reason, in the method for forming the red light-emitting layer 23R according to this embodiment, the photosensitive material 51 having a photoinitiator may be permeated only into the porosity 42 or cracks 43 of the inorganic matrix 41 located in the non-light-emitting region NR. As a result, in the method for forming the red light-emitting layer 23R described above, some of the red quantum dots 31R located in the non-light-emitting region NR are deactivated and become red quantum dots 32R, thus forming the red light-emitting layer 23R according to this embodiment.

[0141] The non-emitting region NR includes an inorganic matrix 41 having porous 42 or cracks 43 filled with photosensitive material 51, and also includes deactivated red quantum dots 32R. Therefore, the red light-emitting element 2R can improve the mechanical strength of the non-emitting region NR of the red light-emitting layer 23R and intentionally reduce the light emission intensity in the non-emitting region NR. In other words, the red light-emitting element 2R according to this embodiment can be designed to mainly extract light from the light-emitting region LR of the red light-emitting layer 23R and reduce the light emission intensity in the non-emitting region NR.

[0142] Therefore, the red light-emitting element 2R according to this embodiment improves the mechanical strength of the red light-emitting layer 23R and increases the design freedom of the light-emitting portion. When the light emission intensity of the red quantum dot 32R is 10% or more lower than the light emission intensity of the red quantum dot 31R, the red light-emitting element 2R can make the difference in light emission intensity between the non-light-emitting region NR and the light-emitting region LR larger, further improving the effects of the design described above.

[0143] In particular, because the non-emitting region NR is located on the edge side in a plan view of the red light-emitting layer 23R, the red light-emitting element 2R can efficiently reduce peeling of the red light-emitting layer 23R due to the non-emitting region NR, which has improved mechanical strength compared to the light-emitting region LR. Furthermore, because the non-emitting region NR is located on the edge side in a plan view of the red light-emitting layer 23R, the red light-emitting element 2R can make the portion of the red light-emitting layer 23R near the light-emitting layers of adjacent colors a non-emitting region NR. Therefore, the red light-emitting element 2R reduces the mixing of red light emitted by the red light-emitting element 2R with light emitted by other light-emitting elements.

[0144] In this embodiment as well, the green light-emitting layer 23G and the blue light-emitting layer 23B may each have the same configuration as the red light-emitting layer 23R shown in Figures 23 and 24, except for the light-emitting color of the quantum dots. In this case, the green light-emitting element 2G and the blue light-emitting element 2B each more effectively increase the mechanical strength of the green light-emitting layer 23G and the blue light-emitting layer 23B, and improve the design freedom of the light-emitting portion. When the non-light-emitting region NR of each light-emitting element is located on the edge side in a plan view of the light-emitting layer 23, the display device 1 reduces color mixing between multiple subpixels and improves display quality.

[0145] [Embodiment 5] <Photosensitive material around the light-emitting layer> The display device 1 according to this embodiment has the same configuration as the display device 1 according to any of the above embodiments, except that the light-emitting element 2 further comprises a photosensitive material 53 which will be described later. The configuration of the display device 1 according to this embodiment will be described with reference to Figures 25 and 26. Figure 25 is a schematic side cross-sectional view of the display device 1 according to this embodiment. Figure 26 is a schematic plan cross-sectional view of the display device 1 according to this embodiment, and in particular is a cross-sectional view taken along the line C-C of the display device 1 shown in Figure 25. From the viewpoint of simplifying the structure of the illustrated display device 1 and making the explanation clearer, the display device 1 according to this embodiment may have a structure in which a part of the structure of the display device 1 according to Modification 1 shown in Figure 3 has been changed. In other words, the display device 1 according to this embodiment may have a bank BK that partitions only the anode 21 into sub-pixels. However, this embodiment is not limited to this, and the light-emitting layer 23 may be partitioned into sub-pixels by the bank BK and the hole transport layer 22, as in the display device 1 shown in Figure 1 or the display device 1 shown in Figure 4.

[0146] As shown in Figure 25, the light-emitting element 2 according to this embodiment includes a photosensitive material 53. The photosensitive material 53 contains the same material as the photosensitive material 51 described above. The photosensitive material 53 is located in at least a portion of the periphery of each of the red light-emitting layer 23R, the green light-emitting layer 23G, and the blue light-emitting layer 23B. In particular, in this embodiment, the photosensitive material 53 is formed, for example, around the periphery of the light-emitting layer 23 located at each subpixel, covering the end of the light-emitting layer 23 in the planar direction DP and the upper surface in the film thickness direction DT of the light-emitting layer 23. In other words, the photosensitive material 53 is located around the periphery of the light-emitting layer 23 located at each subpixel, on the surface facing the electron transport layer 24. Therefore, as shown in Figure 26, in the cross-section of the light-emitting layer 23 on a plane parallel to the planar direction DP of the light-emitting layer 23, the photosensitive material 53 surrounds the periphery of the light-emitting layer 23 located at each subpixel in a planar view of the light-emitting layer 23.

[0147] However, in this embodiment, the configuration of the photosensitive material 53 is not limited to the configuration of the photosensitive material 53 shown in Figures 25 and 26. For example, the photosensitive material 53 may cover only the upper surface of the light-emitting layer 23 on the cathode 25 side of the light-emitting layer 23 located at each subpixel. Alternatively, the photosensitive material 53 may be formed in a plurality of island-like structures around the light-emitting layer 23 located at each subpixel. If the light-emitting layer 23 is partitioned for each subpixel by a bank BK and a hole transport layer 22, a portion of the photosensitive material 53 may be located between the side surface of the light-emitting layer 23 located at each subpixel and the hole transport layer 22.

[0148] The light-emitting layer 23 according to this embodiment may be formed, for example, by patterning a quantum dot layer in the method for forming the light-emitting layer 23 described above, such that a photosensitive material layer remains around the light-emitting layer 23. Alternatively, the light-emitting layer 23 according to this embodiment may be formed, for example, by applying a photosensitive material 53 around the light-emitting layer 23 after performing the method for forming the light-emitting layer 23 described above, and then performing exposure using a photomask and patterning using a developer.

[0149] The light-emitting element 2 according to this embodiment further improves the mechanical strength of the light-emitting layer 23 by providing a photosensitive material 53 that covers at least a portion of the periphery of the light-emitting layer 23. Furthermore, the light-emitting element 2 according to this embodiment can more efficiently penetrate the photosensitive material 53 into the porosity 42 or cracks 43 of the inorganic matrix 41 of the light-emitting layer 23, thereby further improving the mechanical strength of the light-emitting layer 23. Moreover, since the photosensitive material 53 that covers at least a portion of the periphery of the light-emitting layer 23 reduces the penetration of foreign substances such as moisture or oxygen into the light-emitting layer 23, the light-emitting element 2 according to this embodiment improves the reliability of the light-emitting layer 23.

[0150] In particular, when the photosensitive material 53 covers at least a portion of the cathode 25 side of the light-emitting layer 23, the light-emitting element 2 can reduce excessive electron injection from the cathode 25 to the light-emitting layer 23 by the photosensitive material 53. Generally, in light-emitting elements in which the light-emitting material contained in the light-emitting layer is quantum dots, there is a tendency for an excess of electrons in the light-emitting layer to be significant, due to the fact that the mobility of electrons is higher than the mobility of holes. The occurrence of an excess of electrons in the light-emitting layer can lead to deterioration of the light-emitting layer due to the generation of Auger electrons, and can cause a decrease in the luminous efficiency of the light-emitting element. Therefore, the light-emitting element 2 according to this embodiment improves the luminous efficiency by reducing the excess of electrons in the light-emitting layer 23 by providing a photosensitive material 53 that covers at least a portion of the cathode 25 side of the light-emitting layer 23.

[0151] This disclosure is not limited to the embodiments described above, 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 this disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0152] 1 Display device 2 Light-emitting element 3 Substrate 21 Anode 22 Hole transport layer (functional layer) 23 Light-emitting layer (functional layer) 24 Electron transport layer (functional layer) 25 Cathode 31R Red quantum dot (light-emitting material) 31G Green quantum dot (light-emitting material) 31B Blue quantum dot (light-emitting material) 41 Inorganic matrix 42 Porous 43 Crack 51 Photosensitive material 73 Precursor 81 Mixed area LR Light-emitting region NR Non-light-emitting region ER Periphery CR Center

Claims

1. A light-emitting element comprising: an anode; a cathode facing the anode; and at least one functional layer located between the anode and the cathode, and including a light-emitting layer containing at least a light-emitting material, wherein at least one layer of the functional layer includes a plurality of functional materials, an inorganic matrix filling the space between at least two of the functional materials, and a photosensitive material.

2. The light-emitting element according to claim 1, wherein the light-emitting layer comprises a plurality of luminescent quantum dots as a plurality of functional materials, an inorganic matrix filling the space between at least two of the quantum dots, and the photosensitive material.

3. The light-emitting element according to claim 2, wherein the photosensitive material includes a photoresist.

4. The light-emitting element according to claim 3, wherein the photoresist is of the positive type.

5. The light-emitting element according to claim 3, wherein the photoresist is negative type.

6. The light-emitting element according to any one of claims 3 to 5, wherein the photoresist comprises at least one from the group consisting of DNQ, benzophenone compounds, acetophenone compounds, benzoin ether compounds, thioxanthone compounds, iodonium salt compounds, sulfonium salt compounds, primary to tertiary amine compounds, amidine compounds, guanidine compounds, and bisazide compounds.

7. The light-emitting element according to any one of claims 2 to 6, wherein the inorganic matrix surrounds at least one of the quantum dots.

8. The light-emitting element according to any one of claims 2 to 7, wherein the light-emitting layer has a light-emitting region and a non-light-emitting region different from the light-emitting region, and a portion of the quantum dots in the non-light-emitting region are deactivated.

9. The light-emitting element according to claim 8, wherein at least a portion of the quantum dots in the non-emitting region has a light emission intensity that is 10% or more lower than that of at least a portion of the quantum dots in the light-emitting region.

10. The light-emitting layer according to any one of claims 2 to 9, wherein the light-emitting layer has a peripheral portion located on the end side in a plan view and a central portion located on the central side of the peripheral portion in a plan view, and the film thickness of the peripheral portion is greater than the film thickness of the central portion.

11. The light-emitting element according to claim 10, wherein the peripheral portion includes the photosensitive material.

12. The light-emitting element according to any one of claims 1 to 11, wherein the inorganic matrix has at least one of porosity and cracks, and the photosensitive material fills at least a portion of at least one of the porosity and cracks.

13. The light-emitting element according to any one of claims 1 to 11, wherein the inorganic matrix and the photosensitive material are mixed around the functional material.

14. The light-emitting element according to any one of claims 1 to 13, further comprising the photosensitive material covering at least a portion of the periphery of the light-emitting layer.

15. The light-emitting element according to any one of claims 1 to 14, wherein the inorganic matrix comprises at least one of a metal oxide and a metal sulfide.

16. The light-emitting element according to any one of claims 1 to 15, wherein the inorganic matrix is ​​insulating.

17. The light-emitting element according to claim 16, wherein the inorganic matrix comprises at least one of silicon oxide, boron oxide, phosphorus oxide, germanium oxide, beryllium fluoride, arsenic sulfide, silicon selenide, germanium sulfide, titanium oxide, tellurium oxide, aluminum oxide, bismuth oxide, vanadium oxide, antimony oxide, lead oxide, silicon nitride, and magnesium oxide.

18. The light-emitting element according to any one of claims 1 to 17, wherein the inorganic matrix has halogen atoms.

19. A display device comprising a substrate and a plurality of light-emitting elements according to any one of claims 1 to 18 on the substrate.

20. The display device according to claim 19, wherein the plurality of light-emitting elements include a first light-emitting element and a second light-emitting element that emits light of a different wavelength from the first light-emitting element.

21. A method for manufacturing a light-emitting element, comprising: forming an anode; forming a cathode opposite the anode; and forming at least one functional layer located between the anode and the cathode, and including a light-emitting layer containing at least a light-emitting material, wherein the formation of at least one functional layer includes forming a layer comprising a plurality of functional materials, an inorganic matrix filling the space between at least two of the functional materials, and a photosensitive material.

22. The method for manufacturing a light-emitting element according to claim 21, wherein the formation of at least one layer of the functional layer comprises the formation of a light-emitting layer comprising a plurality of luminescent quantum dots as a plurality of functional materials, an inorganic matrix filling the spaces between at least two of the quantum dots, and a photosensitive material, and the formation of the light-emitting layer comprises: forming a photosensitive layer containing the photosensitive material; exposing a portion of the photosensitive layer; removing a portion of the photosensitive layer; applying a quantum dot dispersion containing precursors of the quantum dots and the inorganic matrix; forming a quantum dot layer comprising the quantum dots and the inorganic matrix by converting the precursors in the quantum dot dispersion to the inorganic matrix; and patterning the quantum dot layer by removing the remaining photosensitive layer.

Images