Display device and method for producing display device

Abstract

This display device (1) comprises a substrate (2), a plurality of light-emitting elements (3R, 3G, 3B) including a plurality of quantum dots (QDR, QDG, QDB) and quantum dot layers (33) that have a first inorganic material (4) filling spaces between the plurality of quantum dots, and an inorganic layer (5). The inorganic layer is positioned between at least two of the light-emitting elements. Furthermore, the inorganic layer contains a second inorganic material having a semiconductor or insulator for which the band gap is 2.8 eV or greater.

Description

Display device and method for manufacturing the same

[0001] The present disclosure relates to a display device including a plurality of light-emitting elements containing quantum dots as a light-emitting material, and a method for manufacturing the display device.

[0002] Patent Document 1 discloses a technique for simultaneously depositing an electron blocking layer between a hole transport layer and a light-emitting layer of each light-emitting element on a substrate provided with light-emitting elements.

[0003] Japanese Patent Publication No. 2012-204329

[0004] In display devices equipped with light-emitting elements, quantum dots, which have a narrow half-width of the emission wavelength, can be used as the light-emitting layer of the light-emitting element to realize a display device with a wide color gamut. In this case, in order to ensure the reliability of the light-emitting element and suppress the decrease in brightness over time, it is necessary to simultaneously protect the quantum dots in the light-emitting layer and ensure the manufacturability of the light-emitting layer. In particular, as the size of each pixel has become smaller due to the recent increase in resolution of displays, high-precision patterning is required in the manufacturing process of the light-emitting layer.

[0005] A display device according to one embodiment of the present disclosure includes a substrate, a plurality of light-emitting elements on the substrate, the light-emitting elements including a first electrode and a second electrode, a quantum dot layer located between the first electrode and the second electrode and having a plurality of quantum dots and a first inorganic material filling the spaces between the plurality of quantum dots, and an inorganic layer located between at least two of the light-emitting elements, the inorganic layer including a second inorganic material having a semiconductor or an insulator with a band gap of 2.8 eV or more.

[0006] A method for manufacturing a display device according to one embodiment of the present disclosure includes forming a plurality of light-emitting elements, including preparing a substrate; forming a plurality of first electrodes on the substrate; forming a plurality of quantum dot layers having a plurality of quantum dots and a first inorganic material filling spaces between the quantum dots, at positions overlapping with each of the first electrodes in a planar view of the substrate; and forming at least one second electrode at a position overlapping with each of the first electrodes in a planar view of the substrate; and forming an inorganic layer located between at least two of the light-emitting elements, the inorganic layer including a second inorganic material having a semiconductor or insulator with a band gap of 2.8 eV or more.

[0007] A highly reliable and high-resolution display device is realized.

[0008] 1 is a schematic cross-sectional side view of a display device according to Embodiment 1, a schematic enlarged view of the cross-section, and a schematic view showing a first inorganic material filling spaces between quantum dots. FIG. 1 is a schematic plan view of a display device according to Embodiment 1. FIG. 2 is a schematic enlarged view of one pixel of the display device according to Embodiment 1. FIG. 3 is a flowchart showing an example of a method for manufacturing the display device according to Embodiment 1. FIG. 4 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 5 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 6 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 7 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 8 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 9 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 10 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 11 is a cross-sectional view showing another process in the example of a method for manufacturing the display device according to Embodiment 1. FIG. 12 is a cross-sectional view showing each display device for comparing the display devices according to Comparative Form 1 and Embodiment 1. FIG. 13 is a cross-sectional view showing each display device for comparing the display devices according to Comparative Form 1 and Embodiment 1. FIG. 10 is another schematic cross-sectional side view of each display device for comparing the display devices according to Comparative Example 2 and Embodiment 4.

[0009] [Embodiment 1] <Outline of Display Device> Fig. 2 is a schematic plan view of a display device 1 according to this embodiment. The display device 1 includes a display section DA and a frame section NA formed around the periphery of the display section DA. The display device 1 performs display on the display section DA by controlling light emission from each of a plurality of light-emitting elements (described later) formed in the display section DA. Drivers and the like for driving each of the plurality of light-emitting elements of the display section DA may be formed in the frame section NA.

[0010] <Sub-pixels of display section> Fig. 3 is an enlarged schematic diagram of one pixel of the display section DA in the schematic plan view of the display device 1 shown in Fig. 2, and in particular, an enlarged diagram of the region A1 shown in Fig. 2. However, Fig. 3 shows a cathode 35 and an electron transport layer 34, which will be described later, in a see-through manner.

[0011] As will be described later, the display device 1 includes a plurality of light-emitting elements on a substrate. In particular, the display device 1 includes light-emitting elements in each of the red subpixel SPR, green subpixel SPG, and blue subpixel SPB, and displays an image in the display area DA by individually driving each light-emitting element. For example, the display device 1 includes a red light-emitting element 3R, which is a component of the red subpixel SPR, a green light-emitting element 3G, which is a component of the green subpixel SPG, and a blue light-emitting element 3B, which is a component of the blue subpixel SPB. The display device 1 may also include the red light-emitting element 3R, the green light-emitting element 3G, and the blue light-emitting element 3B, which form one pixel. As will be described later, the display device 1 includes an inorganic layer 5 at a position that overlaps with the periphery of each light-emitting element in a planar view of the substrate 2 of the display device 1. In this embodiment, a planar view of the substrate 2 refers to viewing the substrate 2 from a direction perpendicular to the top surface of the substrate 2, and may be synonymous with viewing the display device 1 from a direction perpendicular to the top surface, which is the light-emitting surface of the display area DA of the display device 1.

[0012] <Outline of the substrate and light-emitting element layer> FIG. 1 shows a schematic cross-sectional side view 101 of a display device 1 according to this embodiment, a schematic enlarged view 102 of the schematic cross-sectional side view 101, and schematic views 103 and 104 showing a first inorganic material that fills spaces between quantum dots, which will be described later.

[0013] 1 is a cross-sectional view taken along line II in Fig. 3, in other words, a diagram showing a cross section in a plane perpendicular to the top surface of the display unit DA and passing through the red light-emitting element 3R, the green light-emitting element 3G, and the blue light-emitting element 3B. Hereinafter, in this specification, all schematic cross-sectional views of the display device show a cross section at the same position as the cross section shown in the schematic cross-sectional side view 101 of the display device 1 shown in Fig. 1.

[0014] The schematic enlarged view 102 of the display device 1 shown in FIG. 1 is an enlarged view of an area A2 shown in the schematic cross-sectional side view 101 of the display device 1.

[0015] 1 are diagrams showing two examples of a set P of two blue quantum dots QD B described below and a region (space) K between them, which are shown in the enlarged schematic diagram 102 of the display device 1. In particular, the diagrams 103 and 104 are diagrams showing sets P1 and P2, which are examples of sets of quantum dots QD1 and QD2, respectively.

[0016] In the display section DA of the display device 1, a substrate 2 such as a glass substrate or a film substrate is provided, and a light-emitting element layer 3 on the substrate 2. The light-emitting element layer 3 includes, in this order from the substrate 2 side toward the upper surface of the display section DA, an anode 31 which is a first electrode, a hole transport layer 32 which is a first charge transport layer, an inorganic layer 5, a quantum dot layer 33, an electron transport layer 34 which is a second charge transport layer, and a cathode 35 which is a second electrode.

[0017] The anode 31 is formed, for example, in an island shape for each sub-pixel, and is connected to each pixel circuit (not shown) formed on the substrate 2. The hole transport layer 32, the electron transport layer 34, and the cathode 35 are formed in common to a plurality of sub-pixels.

[0018] The anode 31 and the cathode 35 are electrodes containing a conductive material and are electrically connected to the hole transport layer 32 and the electron transport layer 34, respectively. When a voltage is applied to at least one of the anode 31 and the cathode 35, holes and electrons are injected from the anode 31 and the cathode 35 into the hole transport layer 32 and the electron transport layer 34, respectively. In this embodiment, the display device 1 may control light emission from each light-emitting element by individually driving the anode 31 while applying a predetermined voltage to the cathode 35.

[0019] In this embodiment, the red subpixel SPR, the green subpixel SPG, and the blue subpixel SPB are each formed at a position where a smaller electrode of each light-emitting element contacts the charge transport layer adjacent to that electrode in a plan view of the substrate 2. In other words, in this embodiment, the red subpixel SPR, the green subpixel SPG, and the blue subpixel SPB are each formed at a position where each anode 31 contacts each hole transport layer 32 in a plan view of the substrate 2. In yet another way, the red subpixel SPR, the green subpixel SPG, and the blue subpixel SPB are each formed in a region where each anode 31 is exposed from a bank 6, which will be described later, in a plan view of the substrate 2.

[0020] As described above, the red light-emitting element 3R, the green light-emitting element 3G, and the blue light-emitting element 3B are located in the red sub-pixel SPR, the green sub-pixel SPG, and the blue sub-pixel SPB, respectively. Therefore, in this embodiment, in a plan view of the substrate 2, the areas where each anode 31 contacts each hole transport layer 32 and overlap with each other define the ranges of the red light-emitting element 3R, the green light-emitting element 3G, and the blue light-emitting element 3B, respectively.

[0021] At least one of the anode 31 and the cathode 35 is a transparent electrode that transmits visible light. Examples of the transparent electrode include ITO, IZO, and SnO. ２ Alternatively, FTO or the like may be used. Either the anode 31 or the cathode 35 may be a reflective electrode. The reflective electrode may contain a metal material that has a high reflectivity for visible light, and the metal material may be, for example, Al, Ag, Cu, or Au alone or an alloy of these.

[0022] The hole transport layer 32 is a layer that transports holes injected from the anode 31 to the quantum dot layer 33. The material of the hole transport layer 32 can be an organic or inorganic material having hole transport properties that has been conventionally used in light-emitting devices containing quantum dots. Examples of materials having hole transport properties include poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-4-sec-butylphenyl))diphenylamine)] (abbreviated as "TFB"), poly[N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine] (abbreviated as "p-TPD"), and polyvinylcarbazole (abbreviated as "PVK"). The hole transport layer 32 may contain only one of these materials having hole transport properties, or may contain a suitable mixture of two or more of them.

[0023] The light-emitting element layer 3 may include a hole injection layer between each anode 31 and the hole transport layer 32. Examples of materials for the hole injection layer include a composite of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS) (abbreviated as "PEDOT:PSS"), NiO (nickel oxide), and CuSCN (copper thiocyanate). The hole injection layer may contain only one of these materials, or may contain an appropriate mixture of two or more of them.

[0024] The electron transport layer 34 is a layer that transports electrons injected from the cathode 35 to the quantum dot layer 33. The electron transport layer 34 can be made of organic or inorganic materials having electron transport properties that have been conventionally used in light-emitting devices containing quantum dots. Examples of materials having electron transport properties include ZnO (zinc oxide) nanoparticles and MgZnO (zinc oxide magnesium) nanoparticles. The electron transport layer 34 may contain only one of these materials having electron transport properties, or may contain a suitable mixture of two or more of them. In this embodiment, the electron transport layer 34 may be divided into subpixels, each containing a red quantum dot layer 33R, a green quantum dot layer 33G, and a blue quantum dot layer 33B, which will be described later.

[0025] <Quantum Dots> The quantum dot layer 33 includes a red quantum dot layer 33R, a green quantum dot layer 33G, and a blue quantum dot layer 33B. The red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B are formed at positions overlapping with the red sub-pixel SPR, the green sub-pixel SPG, and the blue sub-pixel SPB, respectively, in a plan view of the substrate 2.

[0026] The red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B each contain a plurality of red quantum dots QDR, green quantum dots QDG, and blue quantum dots QDB as quantum dots. When each light-emitting element is driven, holes are injected into each quantum dot from the anode 31 via the hole transport layer 32, and electrons are injected into each quantum dot from the cathode 35 via the electron transport layer 34.

[0027] The red quantum dots QDR, green quantum dots QDG, and blue quantum dots QDB are light-emitting materials that emit red light, green light, and blue light, respectively, due to excitons generated by recombination with injected holes and electrons. The quantum dots contained in the quantum dot layer 33 can be any conventionally known quantum dots, such as those having a core / shell structure.

[0028] In the present disclosure, "quantum dots" refers to dots having a maximum width of 100 nm or less. The shape of the quantum dots is not particularly limited as long as it satisfies the above-mentioned maximum width, and is not limited to a spherical three-dimensional shape (circular cross-sectional shape). The shape of the quantum dots may be, for example, a polygonal cross-sectional shape, a rod-like three-dimensional shape, a branch-like three-dimensional shape, a three-dimensional shape with an uneven surface, or a combination thereof.

[0029] The quantum dots are typically made of a semiconductor. The semiconductor may have a certain band gap. The semiconductor may be any material capable of emitting light and may include at least the materials described below. The semiconductor may be capable of emitting red, green, and blue light, respectively. The semiconductor may include, for example, at least one selected from the group consisting of a II-VI compound, a III-V compound, a chalcogenide, and a perovskite compound. Note that a II-VI compound refers to a compound containing a II group element and a VI group element, and a III-V compound refers to a compound containing a III group element and a V group element. Furthermore, a II group element may include a 2 group element and a 12 group element, a III group element may include a 3 group element and a 13 group element, a V group element may include a 5 group element and a 15 group element, and a VI group element may include a 6 group element and a 16 group element.

[0030] The II-VI compound includes, for example, at least one selected from the group consisting of MgS, MgSe, MgTe, CaS, CaSe, CaTe, SrS, SrSe, SrTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, HgS, HgSe, and HgTe.

[0031] The III-V compound includes, for example, at least one selected from the group consisting of GaAs, GaP, InN, InAs, InP, and InSb.

[0032] Chalcogenides are compounds containing a Group VI A(16) element, such as CdS or CdSe. Chalcogenides may also include mixed crystals thereof.

[0033] Perovskite compounds are, for example, compounds of the general formula CsPbX ３ The constituent element X includes at least one element selected from the group consisting of Cl, Br, and I, for example.

[0034] Here, the numbering of element groups using Roman numerals is based on the old IUPAC (International Union of Pure and Applied Chemistry) system or the old CAS (Chemical Abstracts Service) system, and the numbering of element groups using Arabic numerals is based on the current IUPAC system.

[0035] In this embodiment, blue light refers to light having a central emission wavelength in a wavelength band of, for example, 380 nm or more and 500 nm or less. Green light refers to light having a central emission wavelength in a wavelength band of, for example, more than 500 nm and less than 600 nm. Red light refers to light having a central emission wavelength in a wavelength band of, for example, more than 600 nm and less than 780 nm.

[0036] <First Inorganic Material> Furthermore, each of the red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B includes a first inorganic material 4 that fills spaces between the quantum dots.

[0037] Note that "the first inorganic material 4 fills the spaces between the quantum dots" refers to filling the region K between the quantum dots QD1 and QD2, as shown in the schematic diagram 103 of the set P1 in Fig. 1 . Region K is a region surrounded by two straight lines tangent to the opposing peripheries of the quantum dots QD1 and QD2 and the peripheries of the quantum dots QD1 and QD2 in the cross section of the quantum dot layer 33. Therefore, as shown in the schematic diagram 104 of the set P2 in Fig. 1 , region K can exist even if the quantum dots QD1 and QD2 are close to each other, and the first inorganic material 4 fills this region K.

[0038] Furthermore, the phrase "the first inorganic material 4 fills the spaces between the quantum dots" does not necessarily mean that the entire region K between the quantum dot QD1 and the quantum dot QD2 is made of the first inorganic material 4. For example, the region K between the quantum dot QD1 and the quantum dot QD2 may contain a material such as an organic material different from the first inorganic material 4. Specifically, for example, the region K may contain carbon elements at an atomic percentage of less than 5%.

[0039] The first inorganic material 4 may fill regions of the quantum dot layer 33 other than the quantum dots. For example, the outer edges (top and bottom surfaces) of the quantum dot layer 33 may be covered with the first inorganic material 4. Alternatively, the quantum dot layer 33 may be configured such that a portion of the first inorganic material 4 extends from the outer edge of the quantum dot layer 33, and the quantum dots are located away from the outer edge. The outer edge of the quantum dot layer 33 may not be formed solely from the first inorganic material 4, and some of the quantum dots may be exposed from the first inorganic material 4. The first inorganic material 4 may refer to the portion of the quantum dot layer 33 excluding the quantum dots.

[0040] The first inorganic material 4 may contain a plurality of quantum dots. The first inorganic material 4 may be formed so as to fill spaces formed between the plurality of quantum dots. The plurality of quantum dots may be embedded in the first inorganic material 4 at intervals.

[0041] The first inorganic material 4 is formed in a thickness of 1000 nm along a plane direction perpendicular to the film thickness direction. ２ The first inorganic material 4 may include a continuous film having an area of ​​at least 100 nm. The continuous film may be a film that is not separated by materials other than the material that constitutes the continuous film in one plane. The continuous film may be an integrated film that is seamlessly connected by chemical bonds of the first inorganic material 4.

[0042] The first inorganic material 4 may be the same material as the shells contained in each of the multiple quantum dots. In this case, the average distance between adjacent cores (core-to-core distance) may be 3 nm or more. Alternatively, the average distance between adjacent cores may be 0.5 times or more the average core diameter. The core-to-core distance is the average of the shortest distances between 20 adjacent cores. The core-to-core distance may be kept wider than the distance when the shells are in contact with each other. The average core diameter is the average of the core diameters of 20 adjacent cores in cross-sectional observation. The core diameter can be the diameter of a circle having the same area as the core area in cross-sectional observation.

[0043] The concentration of the first inorganic material 4 in the quantum dot layer 33 is, for example, the area ratio occupied by the first inorganic material 4 in the cross section of the quantum dot layer 33. This concentration may be 10% to 90% or 30% to 70% in cross-sectional observation. This concentration may be measured, for example, from the area ratio of an image obtained by cross-sectional observation. When the quantum dots have a core-shell structure, the concentration of the shell may be 1% to 50%. The ratio of the core to shell and the first inorganic material 4 of the quantum dots may be appropriately adjusted so that the total is 100% or less. When the shell and the first inorganic material 4 are indistinguishable, the shell may be included as part of the first inorganic material 4.

[0044] The quantum dot layer 33 may be composed of a plurality of quantum dots and the first inorganic material 4. When the quantum dot layer 33 is analyzed, the intensity of carbon detected due to the chain structure may be equal to or less than noise.

[0045] The material constituting the first inorganic material 4 desirably has a wider band gap than the material constituting the quantum dots (for example, the core material). A semiconductor or an insulator can be used as the material constituting the first inorganic material 4. Examples of the material constituting the first inorganic material 4 include metal sulfides and / or metal oxides. Examples of metal sulfides include zinc sulfide (ZnS), zinc magnesium sulfide (ZnMgS, ZnMgS ２ ), gallium sulfide (GaS, Ga ２ S ３ ), zinc tellurium sulfide (ZnTeS), magnesium sulfide (MgS), zinc gallium sulfide (ZnGa ２ S ４ ), magnesium sulfide (MgGa ２ S ４ The metal oxide may be zinc oxide (ZnO), titanium oxide (TiO ２ ), tin oxide (SnO ２ ), tungsten oxide (WO ３ ), zirconium oxide (ZrO ２) The chemical formulas written in parentheses after the compound names are representative examples. The composition ratios written in the chemical formulas are preferably stoichiometric, so that the composition of the actual compounds is as shown in the chemical formulas, but they do not necessarily have to be stoichiometric.

[0046] The structure of the first inorganic material 4 only needs to be confirmed as having the above-described configuration when observed over a width of about 100 nm in a cross section of the quantum dot layer 33, and it is not necessary to observe the above-described configuration throughout the entire quantum dot layer 33. The first inorganic material 4 may contain, for example, an additive, a substance different from the main inorganic material, such as an inorganic semiconductor.

[0047] The first inorganic material 4 fills the spaces between the quantum dots, thereby strongly protecting the surfaces of the quantum dots, thereby increasing the reliability of the light-emitting elements included in the display device 1 and suppressing the decrease in brightness of the light-emitting elements over their operating time.

[0048] <Addendum to Light-Emitting Element Layer> The light-emitting element layer 3 forms a red light-emitting element 3R by including an anode 31, a hole transport layer 32, a red quantum dot layer 33R, an electron transport layer 34, and a cathode 35 that overlap with the red subpixel SPR in a planar view of the substrate 2. The light-emitting element layer 3 also forms a green light-emitting element 3G by including an anode 31, a hole transport layer 32, a green quantum dot layer 33G, an electron transport layer 34, and a cathode 35 that overlap with the green subpixel SPG in a planar view of the substrate 2. The light-emitting element layer 3 also forms a blue light-emitting element 3B by including an anode 31, a hole transport layer 32, a blue quantum dot layer 33B, an electron transport layer 34, and a cathode 35 that overlap with the blue subpixel SPB in a planar view of the substrate 2.

[0049] The configuration of the light-emitting element layer 3 is not limited to the configuration shown in Fig. 1. For example, the light-emitting element layer 3 may further include a capping layer on the cathode 35 to improve the light extraction efficiency from each light-emitting element.

[0050] In this embodiment, each light-emitting element may extract light from the quantum dot layer 33 from the light-transmitting electrode side of the anode 31 or the cathode 35. In this case, the electrode on the opposite side of the light-transmitting electrode of the anode 31 or the cathode 35 may be light-reflective in order to improve the efficiency of extracting light from the quantum dot layer 33.

[0051] In particular, in this embodiment, when each light-emitting element extracts light from the quantum dot layer 33 from the electrode formed on the substrate 2 side, either the anode 31 or the cathode 35, in this embodiment, the anode 31 side, the substrate 2 may be optically transparent.

[0052] The light-emitting element layer 3 according to this embodiment includes the anode 31 on the substrate 2 side of the anode 31 and the cathode 35, but is not limited to this. For example, the light-emitting element layer 3 may include the cathode 35, the electron transport layer 34, the inorganic layer 5, the quantum dot layer 33, the hole transport layer 32, and the anode 31, in this order, on the substrate 2. In this case, the cathode 35 may be formed in an island shape for each sub-pixel, and each cathode 35 may be electrically connected to a pixel circuit on the substrate 2. Furthermore, the anode 31 may be formed in common to a plurality of sub-pixels.

[0053] <Inorganic Layer> The inorganic layer 5 is located at least between a plurality of light-emitting elements. In this embodiment, the inorganic layer 5 is formed in common to a plurality of sub-pixels, particularly between the hole transport layer 32 and the electron transport layer 34. Therefore, a portion of the inorganic layer 5 is located between the anode 31 and cathode 35 of each light-emitting element.

[0054] 3, part of the inorganic layer 5 is formed at a position overlapping the periphery of the quantum dot layer 33 in a plan view of the substrate 2. In addition, part of the inorganic layer 5 is formed at a position overlapping the anode 31 and the quantum dot layer 33 in a plan view of the substrate 2.

[0055] The second inorganic material contained in the inorganic layer 5 is a semiconductor or an insulator with a band gap of 2.8 eV or more. The chemical formulas of materials that can be used as the second inorganic material are summarized in the following table.

[0056] In the above table, the "Chemical Formula" column indicates the chemical formula of a material that can be used as the second inorganic material, and the "Band Gap (eV)" column indicates the typical band gap of the material represented by the chemical formula in eV. However, for materials that have a range of band gaps, such as materials that have the same chemical formula but whose band gap varies depending on the composition, the "Band Gap (eV)" column indicates the lower and upper limits of the typical band gap.

[0057] In particular, the inorganic layer 5 may have the same configuration regardless of the position in a planar view of the substrate 2. In other words, the inorganic layer 5 may contain the second inorganic material at any position in the display device 1 in a planar view of the substrate 2.

[0058] The inorganic layer 5 according to this embodiment is particularly in contact with both the hole transport layer 32 and the electron transport layer 34. In this case, the band gap of the second inorganic material may be equal to or greater than the band gap of the charge transport layer with which the inorganic layer 5 is in contact, in this embodiment, at least one of the hole transport layer 32 and the electron transport layer 34. Furthermore, the band gap of the second inorganic material may differ from the band gap of at least one of the hole transport layer 32 and the electron transport layer 34 by 0.2 eV or more.

[0059] In this embodiment, the inorganic layer 5 is formed closer to the substrate 2 than the quantum dot layer 33, in other words, closer to the anode 31 than the quantum dot layer 33, but this is not limiting. For example, the inorganic layer 5 may be formed on the side of the quantum dot layer 33 opposite to the substrate 2, in other words, closer to the cathode 35 than the quantum dot layer 33.

[0060] <Bank> The display device 1 further includes a bank 6. The bank 6 separates the plurality of light-emitting elements included in the display device 1. The bank 6 is an insulating layer that absorbs or blocks visible light. The bank 6 is formed on the substrate 2, particularly between the plurality of anodes 31 in a planar view of the substrate 2. The bank 6 may be formed at a position that overlaps the end of each anode 31 in a planar view of the substrate 2. In this case, the bank 6 can reduce the effect of electric field concentration at the end of the anode 31 in each light-emitting element on the injection of holes from the anode 31 to the quantum dot layer 33. Examples of materials for the bank 6 include a photosensitive resin to which a light-absorbing agent such as carbon black has been added. Examples of the photosensitive resin include photosensitive organic insulating materials such as polyimide and acrylic resin.

[0061] <Reduction of Leakage Current> The display device 1 according to this embodiment includes a plurality of quantum dot-containing light-emitting elements, each of which has a plurality of quantum dots and a first inorganic material, and an inorganic layer 5 located between the plurality of light-emitting elements. The inorganic layer 5 includes a second inorganic material having a semiconductor or an insulator with a band gap of 2.8 eV or more.

[0062] Generally, the material used for the quantum dots of a light-emitting element has a band gap roughly corresponding to the emission wavelength of the quantum dot. That is, the band gap [eV] of the quantum dot material is roughly 1240 [eV·nm] divided by the emission wavelength [nm]. For example, if a red quantum dot QDR with an emission wavelength of 620 nm is used, the band gap of the red quantum dot QDR is 2.0 eV. If a green quantum dot QDG with an emission wavelength of 530 nm is used, the band gap of the green quantum dot QDG is 2.3 eV. If a blue quantum dot QDB with an emission wavelength of 450 nm is used, the band gap of the blue quantum dot QDB is 2.8 eV. The band gap of the quantum dot described above may be the band gap of the material of the light-emitting portion of the quantum dot, including the core of a core / shell quantum dot, or may be the band gap of the material of the non-light-emitting portion of the quantum dot, including the shell.

[0063] If the band gap of the inorganic layer 5 is smaller than that of the quantum dots, current will flow through the inorganic layer 5 before being injected into the quantum dots, and therefore the effect of preventing leakage current will not be achieved. On the other hand, if the band gap of the inorganic layer 5 is larger than that of the quantum dots, it can be said that current is unlikely to flow through the inorganic layer 5 at a voltage sufficient for injecting current into the quantum dots, and therefore the band gap of the inorganic layer 5 is preferably larger than that of the quantum dots. In other words, the band gap of the second inorganic material is preferably 2.8 eV or more.

[0064] Therefore, the inorganic layer 5 can reduce the flow of holes injected from the anode 31 to the cathode 35 side, bypassing the quantum dot layer 33 via the inorganic layer 5. Therefore, in the display device 1, the inorganic layer 5 reduces the occurrence of leakage current between the anode 31 and the cathode 35, and suppresses a decrease in the luminous efficiency of each light-emitting element.

[0065] In this embodiment, the band gap of the second inorganic material is, for example, equal to or larger than the band gap of at least one of the hole transport layer 32 and the electron transport layer 34. Furthermore, the band gap of the second inorganic material has a difference of, for example, 0.2 eV or more from the band gap of at least one of the hole transport layer 32 and the electron transport layer 34. This allows the display device 1 to reduce the movement of carriers between the hole transport layer 32 and the electron transport layer 34 in each light-emitting element, bypassing the quantum dot layer 33 via the inorganic layer 5. Therefore, the display device 1 further reduces the occurrence of leakage current between the anode 31 and the cathode 35 due to the inorganic layer 5.

[0066] The inorganic layer 5 may have a thickness of 1 nm or more and 30 nm or less. When the inorganic layer 5 has a thickness of 1 nm or more, the display device 1 not only sufficiently reduces the occurrence of leakage current through the inorganic layer 5 but also more reliably achieves the effect of improving the film-formability of the quantum dot layer 33. When the inorganic layer 5 has a thickness of 30 nm or less, the efficiency of carrier injection into the quantum dot layer 33 through the inorganic layer 5 is improved, thereby reducing the resistance of the entire light-emitting element. From the viewpoint of further reducing the resistance of the entire light-emitting element, the inorganic layer 5 may have a thickness of 2 nm or less.

[0067] In particular, the inorganic layer 5 may contain aluminum oxide as the second inorganic material. For example, the second inorganic material may contain alumina (Al ２ O ３ As shown in the table above, alumina (Al ２ O ３ ) has a relatively large band gap of 7 to 9.9 eV. In this way, since the inorganic layer 5 contains aluminum oxide having a large band gap as the second inorganic material, the inorganic layer 5 in the display device 1 can further reduce the occurrence of leakage current.

[0068] Generally, the first inorganic material 4 filling the spaces between the quantum dots in the quantum dot layer 33 has a higher electron mobility than a hole mobility. Therefore, in the light-emitting element according to this embodiment, the electron concentration in the quantum dot layer 33 tends to be higher than the hole concentration. Therefore, when the light-emitting element layer 3 includes the cathode 35, the electron transport layer 34, the inorganic layer 5, the quantum dot layer 33, the hole transport layer 32, and the anode 31 on the substrate 2 in this order, the inorganic layer 5 suppresses the injection of electrons into the quantum dot layer 33 in each light-emitting element. Therefore, when the light-emitting element layer 3 has the above-described configuration, the display device 1 suppresses an excess of electrons in the quantum dot layer 33, thereby further improving the luminous efficiency and reliability of each light-emitting element.

[0069] <Display Device Manufacturing Method: Overview> A method for manufacturing the display device 1 according to this embodiment will be described in detail with reference to Figs. 4 to 9. Fig. 4 is a flowchart for explaining the method for manufacturing the display device 1 according to this embodiment. Figs. 5 to 9 are cross-sectional views showing some steps in the method for manufacturing the display device 1 according to this embodiment. In particular, Figs. 5 to 9 show cross sections at the same positions as the cross section shown in the schematic side cross-sectional view 101 of the display device 1 shown in Fig. 1.

[0070] 4, in the method for manufacturing a display device according to this embodiment, first, a substrate 2 is prepared (step S1). In this embodiment, for example, a thin-film transistor may be formed for each sub-pixel on a glass substrate or a film substrate to manufacture the substrate 2, thereby providing a pixel circuit for each sub-pixel. In addition, a frame portion NA may be formed by forming a driver or the like on the periphery of the substrate 2.

[0071] Next, the anode 31 is formed on the substrate 2 (step S2). The anode 31 may be formed, for example, by forming a thin film of a metal material or the like on the substrate 2 by a sputtering method, a vapor deposition method, or the like, and then patterning the film by dry etching or the like.

[0072] Next, the bank 6 is formed on the substrate 2 and the anode 31 (step S3). The bank 6 may be formed, for example, by applying a photosensitive resin material onto the substrate 2 and the anode 31 and then patterning the applied material by photolithography or the like.

[0073] Next, a hole transport layer 32 is formed on the anode 31 and the bank 6 (step S4). The hole transport layer 32 may be formed, for example, by applying a material having hole transport properties onto the anode 31 and the bank 6.

[0074] Next, the inorganic layer 5 is formed on the hole transport layer 32 (step S5). The inorganic layer 5 may be formed from, for example, a coating material containing a precursor of the second inorganic material. In this case, for example, the coating material may be coated on the hole transport layer 32 and then heated to form the second inorganic material from the precursor in the coating material. For example, potassium sulfide (solvent: ethanol), zinc chloride (solvent: ethanol), etc., may be used. ２＋ and S ２－ ZnS can be formed as the second inorganic material by alternately applying a solution containing ZnS about 10 times. Since it is not necessary to disperse quantum dots in the solution in this step, ethanol (dielectric constant 25) can be used, which has low polarity (low dielectric constant) and good coating properties compared to the solvent used in forming the quantum dot layer described below. In step S5, baking may be performed to volatilize the solvent in the applied material. As a result, a laminate including the substrate 2 and the inorganic layer 5 is obtained, as shown in step S5 of FIG. 5 . Note that the method for forming the inorganic layer 5 is not limited to this, as long as the inorganic layer 5 is formed between multiple light-emitting elements. For example, in the process of forming the inorganic layer 5, the inorganic layer 5 may be formed only in desired locations by patterning using a lift-off method using photolithography or the like.

[0075] <Display Device Manufacturing Method: Formation of Quantum Dot Layer> Next, the quantum dot layer 33 is formed. In this embodiment, an example will be described in which, in the step of forming the quantum dot layer 33, a red quantum dot layer 33R, a green quantum dot layer 33G, and a blue quantum dot layer 33B are formed in this order.

[0076] In the process of forming the quantum dot layer 33, for example, first, a photosensitive resin layer 7 is formed (step S6). For example, as shown in step S6-1 in Fig. 5, the photosensitive resin layer 7 is formed by applying a photosensitive resin onto the inorganic layer 5. Here, in this embodiment, an example will be described in which the photosensitive resin layer 7 contains a positive photosensitive resin.

[0077] Following step S6, a portion of the applied photosensitive resin layer 7 is exposed to light. In step S7 of the process of forming the red quantum dot layer 33R, for example, as shown in step S7-1 of FIG. 5 , a mask M is placed that blocks ultraviolet light and has a transmission portion, such as an opening, that transmits ultraviolet light at a position corresponding to the red sub-pixel SPR. Next, ultraviolet light UV is irradiated onto the photosensitive resin layer 7 from above the mask M. As a result, as shown in step S7-1 of FIG. 5 , only the portion of the photosensitive resin layer 7 that is located at the position corresponding to the red sub-pixel SPR is irradiated with ultraviolet light UV, and this portion becomes an exposed portion 7A.

[0078] Following step S7, the photosensitive resin layer 7 including the exposed portions 7A is washed with an appropriate developer (step S8). In this case, for example, a developer that is poorly soluble in the unexposed photosensitive resin layer 7 and highly soluble in the exposed portions 7A is used. The developer may be, for example, an alkaline solution containing TMAH or the like. As a result, the photosensitive resin layer 7 is peeled off only from the positions corresponding to the red sub-pixels SPR, as shown in step S8-1 of FIG. 6 .

[0079] Following step S8, a quantum dot material layer is formed (step S9). In step S9 of the process of forming the red quantum dot layer 33R, for example, as shown in step S9-1 of FIG. 6, a red quantum dot material layer 8R is formed by coating on the photosensitive resin layer 7 and on the inorganic layer 5 exposed after the photosensitive resin layer 7 has been peeled off. The red quantum dot material layer 8R is formed by coating a coating material obtained by mixing a plurality of red quantum dots QDR with a solution in which a precursor 81 of the first inorganic material 4 is dispersed in a solvent. Examples of the coating material include ZnS as the first inorganic material, zinc thiourea as its precursor 81, and DMF (N,N-dimethylformamide, dielectric constant 37) as the solvent. To disperse the quantum dots in the solvent of the coating material, it is preferable to use a highly polar (high dielectric constant) solvent. Generally, highly polar solvents have poor wettability on the hydrophobic organic hole transport layer, making it difficult to apply the solvent uniformly. However, by forming the hydrophilic inorganic layer 5 in advance, the wettability can be improved, and a uniform quantum dot material layer can be formed.

[0080] Following step S9, the remaining photosensitive resin layer 7 is peeled off (step S10). The photosensitive resin layer 7 may be peeled off, for example, by washing the photosensitive resin layer 7 with an organic solvent such as PGMEA. Here, in step S10, a material that does not dissolve materials other than the inorganic layer 5 and the photosensitive resin layer 7 on the inorganic layer 5 is used.

[0081] As a result, in step S10 of the process of forming the red quantum dot layer 33R, the photosensitive resin layer 7 is peeled off and the red quantum dot material layer 8R located on the photosensitive resin layer 7 is removed. Therefore, for example, as shown in step S10-1 in FIG. 6 , the red quantum dot material layer 8R remains only in the position corresponding to the red sub-pixel SPR.

[0082] Following step S10, the quantum dot material layer is heated at a high temperature (step S11). In step S11, for example, the quantum dot layer may be heated in a 250°C atmosphere for 30 minutes. As a result, for example, in step S11 of the process of forming the red quantum dot layer 33R, the precursor 81 in the red quantum dot material layer 8R reacts to form the first inorganic material 4.

[0083] Here, the precursor 81 in the red quantum dot material layer 8R is sequentially formed around the red quantum dots QDR in the red quantum dot material layer 8R by heating in step S11. Therefore, in step S11, the first inorganic material 4 is formed so as to fill the spaces between the multiple red quantum dots QDR.

[0084] As a result of the above, as shown in step S11-1 of FIG. 7, the red quantum dot layer 33R is formed on the inorganic layer 5 at a position corresponding to the red sub-pixel SPR.

[0085] The above-described steps S6 to S11 are repeatedly performed until quantum dot layers of all luminescent colors are formed. For example, in this embodiment, the step of forming the green quantum dot layer 33G is performed after the step of forming the red quantum dot layer 33R.

[0086] 7, in step S6 of the process of forming the green quantum dot layer 33G, the photosensitive resin layer 7 is formed not only on the inorganic layer 5 but also on the already formed red quantum dot layer 33R. Here, the red quantum dots QDR of the red quantum dot layer 33R are protected by the first inorganic material 4, and therefore the first inorganic material 4 can reduce the influence of the photosensitive resin layer 7 on the red quantum dots QDR.

[0087] For example, in step S7 of the process of forming the green quantum dot layer 33G, the portions of the photosensitive resin layer 7 corresponding to the green sub-pixels SPG are exposed to light 7A, as shown in step S7-2 of Fig. 7. Therefore, in the subsequent step S8, the photosensitive resin layer 7 is peeled off only from the positions corresponding to the green sub-pixels SPG, as shown in step S8-2 of Fig. 8.

[0088] 8 , a green quantum dot material layer 8G is formed by mixing green quantum dots QDG into a precursor 81. In step S10 of the process of forming the green quantum dot layer 33G, as shown in step S10-2 of FIG. 8 , the green quantum dot material layer 8G remains only in positions corresponding to the green sub-pixels SPG. Here, the red quantum dots QDR of the red quantum dot layer 33R are protected by the first inorganic material 4, and the first inorganic material 4 can reduce the influence of the peeling process of the photosensitive resin layer 7 in step S10 on the red quantum dots QDR.

[0089] 9 , the green quantum dot layer 33G is formed on the inorganic layer 5 at a position corresponding to the green sub-pixel SPG by heating the green quantum dot material layer 8G. Note that, even in step S11 of the formation process of the green quantum dot layer 33G, the red quantum dots QDR of the red quantum dot layer 33R are protected by the first inorganic material 4. Therefore, according to the manufacturing method of the display device 1 according to this embodiment, it is possible to reduce deterioration of the red quantum dot QDR due to heating of the green quantum dot material layer 8G.

[0090] Subsequently, steps S6 to S11 are performed in the same manner as described above, thereby forming a blue quantum dot layer 33B on the inorganic layer 5 at a position corresponding to the blue sub-pixel SPB, as shown in step S11-3 of FIG. In this manner, the quantum dot layer 33 is formed. Note that even during the process of forming the blue quantum dot layer 33B, the red quantum dots QDR and the green quantum dots QDG are protected by the first inorganic material 4. Therefore, the first inorganic material 4 can reduce the influence of the process of forming the blue quantum dot layer 33B on the red quantum dots QDR and the green quantum dots QDG.

[0091] As described above, in the example of the method for manufacturing the display device 1 according to this embodiment, the quantum dot material layer formed in common to a plurality of subpixels is patterned to form the quantum dot layer 33. Here, as described above, in the patterning of the quantum dot material layer, all of the quantum dots in the quantum dot layer 33 that have already been formed are protected by the first inorganic material 4. Therefore, according to the method for manufacturing the display device 1 according to this embodiment, patterning the quantum dot material layer makes it easier to form the quantum dot layer 33 for each subpixel, while reducing deterioration of the quantum dots in the quantum dot layer 33 due to the patterning.

[0092] Here, for example, an organic material may be used in the hole transport layer 32 to further improve the hole injection efficiency. In this case, when a quantum dot material layer containing a precursor 81 of the first inorganic material 4 is applied onto the hole transport layer 32, which is a layer of an organic material, the film formability of the quantum dot material layer may be reduced, and the quality of the quantum dot layer 33, including the uniformity of the film thickness of the quantum dot layer 33, may be reduced.

[0093] In an example of the manufacturing method for the display device 1 according to this embodiment, the quantum dot layer 33 is formed on the inorganic layer 5. The film-forming properties of the quantum dot material layer on the inorganic layer 5 containing the second inorganic material are improved compared to the film-forming properties of the quantum dot material layer on the hole transport layer 32 containing an organic material. Therefore, the manufacturing method for the display device 1 according to this embodiment improves the quality of the quantum dot layer 33, including the uniformity of the film thickness of the quantum dot layer 33.

[0094] For example, the first inorganic material 4 and the second inorganic material may contain the same inorganic material. In this case, the film formation property of the quantum dot material layer in step S9 is improved. When the first inorganic material 4 and the second inorganic material are made of the same inorganic material, the bottom surface of each quantum dot layer may be a straight line (common tangent) connecting the bottommost points of the multiple quantum dots in the quantum dot layer, which may be the boundary between the inorganic layer 5 and each quantum dot.

[0095] Furthermore, for example, the first inorganic material 4 and the second inorganic material may be zinc sulfide (ZnS) or zinc magnesium sulfide (ZnMgS, ZnMgS ２ In this case, the film-forming properties of the quantum dot material layer in step S9 can be improved, and the effect of protecting the quantum dots by the first inorganic material 4 can be enhanced.

[0096] <Display Device Manufacturing Method: After Formation of Electron Transport Layer> Following the formation of the quantum dot layer 33, the electron transport layer 34 is formed on the inorganic layer 5 and the quantum dot layer 33 (step S12). The electron transport layer 34 may be formed, for example, by applying a material having electron transport properties onto the inorganic layer 5 and the quantum dot layer 33. As a result, as shown in step S12 of Fig. 9, the electron transport layer 34 is formed in contact with the inorganic layer 5 and the quantum dot layer 33 but not in direct contact with the hole transport layer 32.

[0097] In step S12, the electron transport layer 34 may also be formed on the side surfaces of and between the red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B. Thus, in step S12, the electron transport layer 34 may be formed to partition the red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B into subpixels.

[0098] Next, a cathode 35 is formed on the electron transport layer 34 (step S13). The cathode 35 may be formed, for example, by depositing a thin film of a metal material or the like on the electron transport layer 34 by sputtering or the like. A sealing layer (not shown) may be formed on the cathode 35 to prevent the intrusion of foreign matter, such as moisture, oxygen, and excess organic matter such as dust generated during the manufacturing process, into the light-emitting element. Furthermore, a functional film, touch panel, polarizing plate, or the like having at least one of an optical compensation function, a touch sensor function, and a protective function may be formed on the sealing layer as needed. As a result, the light-emitting element layer 3 illustrated in FIG. 1 is formed on the substrate 2, completing the manufacturing process of the display device 1.

[0099] The manufacturing method of the display device 1 is not limited to this, and for example, the quantum dot layer 33 may be formed after the hole transport layer 32 is formed, and then the inorganic layer 5 may be formed. In this case, the display device 1 can be manufactured with a plurality of light-emitting elements including the inorganic layer 5 on the cathode 35 side of the quantum dot layer 33.

[0100] <Leakage Current of Display Device According to Comparative Embodiment> The mechanism for reducing leakage current in each light-emitting element of display device 1 according to this embodiment will be described while comparing it with a display device according to a comparative embodiment. Figure 10 is a schematic cross-sectional side view 1001 of display device 1A according to comparative embodiment 1 and a schematic cross-sectional side view 1002 of display device 1 according to this embodiment.

[0101] 10 shows examples of display devices in which a deviation in the formation position of the blue quantum dot layer 33B occurs during the manufacturing process of each display device. For example, if the installation position of the mask M is deviated from its original position in step S7 of the manufacturing method of the display device 1 described above, the position of the exposure unit 7A will also be deviated, which may result in a deviation in the formation position of the quantum dot layer 33. Furthermore, a deviation in the formation position of the quantum dot layer 33 may be caused, for example, by deformation of the mask M due to stress generation on the mask M or a change in temperature, or deformation of the substrate 2 due to stress generation on the substrate 2 or a change in temperature.

[0102] When forming a light-emitting layer in which quantum dots are filled in the first inorganic material 4, the precursor 81 must be reacted to form the first inorganic material 4, and therefore the material containing the precursor 81 must be heated at a high temperature. During this heating process, heat is likely to be applied to the mask M or the substrate 2, which can easily cause misalignment of the mask M. Furthermore, in high-resolution displays with small pixel sizes, the misalignment of the mask M relative to the pixel position is relatively large, making this problem more likely to occur. Even in such cases, the present disclosure can effectively reduce the leakage current described below and suppress a decrease in the luminous efficiency of each light-emitting element.

[0103] In particular, Figure 10 shows an example in which, due to a misalignment in the formation position of the blue quantum dot layer 33B, there is a position in each display device where the anode 31 of the blue sub-pixel SPB and the blue quantum dot layer 33B do not overlap when viewed in plan on the substrate 2.

[0104] Unlike the display device 1 according to the present embodiment, the display device 1A according to Comparative Example 1 does not include the inorganic layer 5. Therefore, the display device 1A includes a portion where the hole transport layer 32 and the electron transport layer 34 are in direct contact with each other. Therefore, as shown in a schematic side cross-sectional view 1001 of the display device 1A in FIG. 10 , a leakage current LC1 may occur from the anode 31, passing through the hole transport layer 32 and the electron transport layer 34 in this order, to the cathode 35. Because the leakage current LC1 does not pass through the quantum dot layer 33 and does not contribute to the light emission of each light-emitting element, the occurrence of the leakage current LC1 reduces the light-emitting efficiency of each light-emitting element of the display device 1A.

[0105] Furthermore, as described above, in the display device 1A, there is a position in the plan view of the substrate 2 where the anode 31 of the blue subpixel SPB does not overlap with the blue quantum dot layer 33B. At this position, as shown in the schematic side cross-sectional view 1001 of the display device 1A in FIG. 10 , a leakage current LC2 may be generated that flows from the anode 31 to the cathode 35 without passing through the quantum dot layer 33, in substantially the same direction as the stacking direction of the blue light-emitting element 3B. Because the path of the leakage current LC2 is substantially the shortest path from the anode 31 to the cathode 35, the intensity of the leakage current LC2 tends to be greater than the intensity of the leakage current LC1. Therefore, if a deviation occurs in the formation position of the quantum dot layer 33 during the manufacturing process of the display device 1A, the luminous efficiency of each light-emitting element of the display device 1A may be further reduced.

[0106] <Leakage Current Reduction Mechanism> On the other hand, the display device 1 according to this embodiment includes the inorganic layer 5, and therefore does not have a portion where the hole transport layer 32 and the electron transport layer 34 are in contact with each other. Therefore, as shown in the schematic side cross-sectional view 1002 of the display device 1 in Fig. 10 , the leakage current LC3 that attempts to flow from the anode 31 through the hole transport layer 32 and bypass the quantum dot layer 33 to the electron transport layer 34 and the cathode 35 is reduced by the inorganic layer 5.

[0107] Furthermore, the band gap of the second inorganic material contained in the inorganic layer 5 is 2.8 eV or more. Therefore, for the reasons described above, the display device 1 can make the intensity of the current flowing through the inorganic layer 5 to the quantum dot layer 33 greater than the intensity of the leakage current that bypasses the quantum dot layer 33 via the inorganic layer 5.

[0108] Therefore, the display device 1 reduces the intensity of the generated leakage current and reduces the suppression of the luminous efficiency of each light-emitting element.

[0109] Note that each quantum dot layer according to this embodiment may be formed, in plan view, on the periphery side of the position where each anode 31 contacts the hole transport layer 32. In this case, the display device 1 has the inorganic layer 5 located between the plurality of light-emitting elements, which reduces the leakage current from flowing through the quantum dot layer formed at the above position, thereby reducing abnormal light emission occurring outside the light-emitting elements.

[0110] Furthermore, the inorganic layer 5 according to this embodiment is also formed between the anode 31 and cathode 35 of each light-emitting element. Therefore, in the display device 1, even if there is a position where the anode 31 of the blue sub-pixel SPB and the blue quantum dot layer 33B do not overlap in a plan view of the substrate 2, the inorganic layer 5 is formed at that position. Therefore, the display device 1 can reduce the intensity of the leakage current LC4 that attempts to flow between the anode 31 and the cathode 35 via approximately the shortest path.

[0111] Therefore, in the display device 1, even if the quantum dot layer 33 is formed at a misaligned position, the intensity of the leak current that occurs is reduced, and the reduction in the luminous efficiency of each light-emitting element is suppressed.

[0112] For example, the magnitude of the diode current is proportional to the intrinsic carrier density of the semiconductor, in other words, the band gap of the semiconductor is E ｇ As exp(-E ｇ / kT), where k is the Boltzmann constant and T is the temperature of the semiconductor.

[0113] Here, as the material for the electron transport layer 34, ZnO (having a band gap E ｇ In this case, the leakage current flowing from the hole transport layer 32 to the electron transport layer 34 at the contact portion between the hole transport layer 32 and the electron transport layer 34 is expressed as exp(-E ｇ / kT) = 2 × 10 －２８ is proportional to.

[0114] On the other hand, as the second inorganic material, ZnS (band gap E ｇIn this case, the leakage current flowing from the hole transport layer 32 to the electron transport layer 34 through the inorganic layer 5 at the contact portion between the hole transport layer 32 and the inorganic layer 5 is expressed as exp(-E ｇ / kT) = 6 x 10 －３１ In this case, the display device 1 according to this embodiment can reduce the leakage current flowing from the hole transport layer 32 to the electron transport layer 34 by about three orders of magnitude compared to a case where the inorganic layer 5 is not provided.

[0115] In addition, the second inorganic material has a band gap E ｇ In this case, the leakage current flowing from the hole transport layer 32 to the electron transport layer 34 through the inorganic layer 5 at the contact portion between the hole transport layer 32 and the inorganic layer 5 is expressed as exp(-E ｇ / kT) = 4 x 10 －３０ Even in this case, the display device 1 according to this embodiment can reduce the leakage current flowing from the hole transport layer 32 to the electron transport layer 34 by about two orders of magnitude compared to a case in which the inorganic layer 5 is not provided.

[0116] Therefore, the band gap of the second inorganic material may be equal to or greater than the band gap of the hole transport layer 32. Furthermore, the band gap of the second inorganic material may differ from the band gap of the hole transport layer 32 by 0.2 eV or more, or by 0.3 eV or more. This allows the display device 1 to improve the efficiency of hole injection from the hole transport layer 32 to the quantum dot layer 33 via the inorganic layer 5 in each light-emitting element, thereby further reducing the occurrence of leakage current. Furthermore, from the viewpoint of sufficiently reducing leakage current flowing from the hole transport layer 32 to the electron transport layer 34, the band gap of the second inorganic material of the inorganic layer 5 may be 3.5 eV or more, or may be 3.6 eV or more.

[0117] [Embodiment 2] <Inorganic layer having a thickness that varies depending on the position> Another embodiment of the present disclosure will be described below. For convenience of explanation, the same reference numerals will be used to designate components having the same functions as those described in the above embodiment, and the description thereof will not be repeated.

[0118] 11 is a schematic side cross-sectional view of the display device 1 according to this embodiment. 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 thickness of the inorganic layer 5.

[0119] The inorganic layer 5 according to this embodiment has a different thickness depending on the position in a plan view of the substrate 2. In particular, the thickness of the inorganic layer 5 in contact with the quantum dot layer 33 is smaller than the thickness of the inorganic layer 5 overlapping the periphery of the quantum dot layer 33 in a plan view of the substrate 2.

[0120] Therefore, in the display device 1 according to this embodiment, the inorganic layer 5 can further reduce the intensity of the leakage current LC that tends to bypass the quantum dot layer 33. Meanwhile, the display device 1 can maintain the efficiency of hole injection from the hole transport layer 32 to the quantum dot layer 33 in each light-emitting element. Therefore, the display device 1 can maintain the luminous efficiency of each light-emitting element while reducing the leakage current in each light-emitting element.

[0121] The display device 1 according to this embodiment can be manufactured by the same method as that described in the previous embodiment, by changing only a part of step S9. In step S9 of the method for manufacturing the display device 1 according to this embodiment, a highly polar solvent is used as the solvent for dispersing the plurality of quantum dots and the precursor 81 of the first inorganic material 4, so that the quantum dot material is dissolved in the solution to be applied to the inorganic layer 5 when the quantum dot material is applied.

[0122] As a result, in step S9, the portion of the inorganic layer 5 in contact with the quantum dot material layer is dissolved in the solution, reducing the film thickness of that portion. In this state, by performing the subsequent steps S10 and S11, a quantum dot layer 33 is formed, part of which penetrates into the inorganic layer 5 toward the substrate 2. As a result, the inorganic layer 5 is formed such that the thickness of the portion in contact with the quantum dot layer 33 is smaller than the thickness of the portion that overlaps with the periphery of the quantum dot layer 33 in a plan view of the substrate 2.

[0123] To achieve the above manufacturing method, it is sufficient that the precursor 81 of the quantum dot material layer and the second inorganic material of the inorganic layer 5 are soluble in each other. For example, the first inorganic material 4 and the second inorganic material may be the same material. In this case, the solubility of the precursor 81 of the quantum dot material layer and the second inorganic material of the inorganic layer 5 in each other can be improved.

[0124] According to the above-described manufacturing method, even if the formation position of the quantum dot layer 33 is shifted due to misalignment of the mask M or the like, it is possible to reduce only the film thickness of the inorganic layer 5 in contact with the quantum dot layer 33. As a result, the display device 1 according to this embodiment reduces the intensity of the generated leakage current and suppresses a decrease in the luminous efficiency of each light-emitting element, even if the formation position of the quantum dot layer 33 is shifted. Furthermore, since the film thickness of the inorganic layer 5 in contact with the quantum dot layer 33 is small, it is possible to improve current injection into the quantum dot layer 33 and increase the luminous efficiency.

[0125] 12 is a schematic side cross-sectional view of a display device 1 according to this embodiment. The display device 1 according to this embodiment has the same configuration as the display device 1 according to each of the above-described embodiments, except for the position where the inorganic layer 5 is formed.

[0126] The inorganic layer 5 according to this embodiment is formed only at a position that overlaps with the periphery of the quantum dot layer 33 in a plan view of the substrate 2. In other words, the inorganic layer 5 is not formed at a position that overlaps with the quantum dot layer 33 in a plan view of the substrate 2.

[0127] Therefore, in the display device 1 according to this embodiment, the inorganic layer 5 can further reduce the intensity of the leakage current LC that tends to flow bypassing the quantum dot layer 33. Meanwhile, the display device 1 can further improve the efficiency of hole injection from the hole transport layer 32 to the quantum dot layer 33 in each light-emitting element. Therefore, the display device 1 can improve the luminous efficiency of each light-emitting element while reducing the leakage current in each light-emitting element.

[0128] The display device 1 according to this embodiment can be manufactured by the same method as the above-described method for manufacturing the display device 1, by changing only a part of step S9. In step S9 of the method for manufacturing the display device 1 according to this embodiment, a solvent with higher polarity is used as the solvent for dispersing the plurality of quantum dots and the precursor 81 of the first inorganic material 4, so that the quantum dot material is dissolved in the solution to be applied to the inorganic layer 5 when the quantum dot material is applied.

[0129] As a result, in step S9, the portion of the inorganic layer 5 that is in contact with the quantum dot material layer is dissolved in the solution and disappears, bringing the quantum dot layer 33 into contact with the hole transport layer 32. In this state, by performing the subsequent steps S10 and S11, the quantum dot layer 33 is formed, penetrating the inorganic layer 5 toward the substrate 2 and in contact with the hole transport layer 32. As a result, the inorganic layer 5 is formed only in the portion that overlaps with the periphery of the quantum dot layer 33 in a plan view of the substrate 2.

[0130] According to the above-described manufacturing method, even if the formation position of the quantum dot layer 33 is shifted, the inorganic layer 5 can be formed only in the portion of the substrate 2 that overlaps with the periphery of the quantum dot layer 33 in a planar view. As a result, the display device 1 according to this embodiment reduces the intensity of the generated leakage current and suppresses a decrease in the luminous efficiency of each light-emitting element, even if the formation position of the quantum dot layer 33 is shifted. Furthermore, since there is no inorganic layer 5 that contacts the quantum dot layer 33 in the stacking direction of the light-emitting elements, current injection into the quantum dot layer 33 can be improved, thereby increasing the luminous efficiency.

[0131] 13 is a schematic side cross-sectional view of a display device 1 according to this embodiment. The display device 1 according to this embodiment differs from the display devices 1 according to the above-described embodiments in that the height of the banks 6 from the substrate 2 is different. In particular, in this embodiment, the banks 6 are formed from the upper surface of the substrate 2 to the lower surface of the cathode 35 of the light-emitting element layer 3.

[0132] Therefore, the bank 6 separates the hole transport layer 32, the quantum dot layer 33, and the electron transport layer 34 into sub-pixels in addition to the anode 31. In other words, the bank 6 according to this embodiment separates the plurality of light-emitting elements included in the display device 1.

[0133] In this embodiment, the inorganic layer 5 is also formed on the side surfaces of the bank 6, and therefore, in each light-emitting element, the inorganic layer 5 is in contact with the side surfaces of the quantum dot layer 33 and the electron transport layer 34. Therefore, at least a portion of the inorganic layer 5 is located between the electron transport layer 34 and the bank 6.

[0134] In this embodiment, the inorganic layer 5 is partitioned into sub-pixels by the banks 6, but this is not limiting. For example, the inorganic layer 5 may also be formed on the top surface of the banks 6, and accordingly, may be formed in common to a plurality of sub-pixels.

[0135] Except for the above, the display device 1 according to this embodiment may have the same configuration as the display device 1 according to each of the above-described embodiments. In particular, also in this embodiment, the inorganic layer 5 includes a second inorganic material having a semiconductor or insulator with a band gap of 2.8 eV or more. Therefore, even when the inorganic layer 5 contacts the side surface of the electron transport layer 34 as shown in FIG. 13 , the display device 1 can reduce the flow of holes injected from the anode 31 to the electron transport layer 34 and the cathode 35 via the inorganic layer 5. Therefore, in the display device 1, the inorganic layer 5 reduces the occurrence of leakage current between the anode 31 and the cathode 35, thereby suppressing a decrease in the luminous efficiency of each light-emitting element.

[0136] <Another Example of Manufacturing Method of Display Device> An example of a manufacturing method of the display device 1 according to this embodiment will be described in detail with reference to Figs. 14 to 16. Fig. 14 is a flowchart for explaining the manufacturing method of the display device 1 according to this embodiment. Figs. 15 and 16 are cross-sectional views showing some steps of the manufacturing method of the display device 1 according to this embodiment. In particular, Figs. 15 and 16 show cross sections at the same positions as the cross section shown in the schematic side cross-sectional view of the display device 1 shown in Fig. 13.

[0137] 4 , in the manufacturing method of a display device according to this embodiment, first, the above-described steps S1 to S4 are performed. However, in step S3, banks 6 are formed to separate the plurality of anodes 31 so that the height of the banks 6 will be such that the light-emitting element layer 3, from the hole transport layer 32 to the electron transport layer 34, will be separated by the banks 6 in a subsequent process. In addition, in step S4, the hole transport layer 32 may be formed by individually ejecting the material for the hole transport layer 32 by an inkjet method or the like onto each anode 31 and between the banks 6 in a planar view of the substrate 2. In this manner, the anodes 31, banks 6, and hole transport layer 32 are formed on the substrate 2.

[0138] Following step S4, in the example of the manufacturing method of the display device 1 according to this embodiment, the inorganic layer 5 is formed by coating (step S14). For example, in step S14, a precursor of the second inorganic material may be individually ejected by an inkjet method or the like onto each hole transport layer 32 and between the banks 6 in a planar view of the substrate 2. In this case, the inorganic layer 5 may then be formed by heating the precursor of the second inorganic material. As a result, the inorganic layer 5 may be formed on the hole transport layer 32 and at positions including the side surfaces of the banks 6, as shown in step S14 of FIG. 15 .

[0139] As described above, the inorganic layer 5 may have the same configuration regardless of its position in a plan view of the substrate 2. Therefore, even if the precursor of the second inorganic material ejected in the coating formation of the inorganic layer 5 flows beyond the bank 6, there is little effect on subsequent processes and on the performance of the manufactured display device 1.

[0140] Therefore, in step S14, the amount of the precursor of the second inorganic material ejected at the positions corresponding to each subpixel may be increased. Alternatively, in step S14, a layer of the precursor of the second inorganic material may be deposited commonly for multiple subpixels. This improves the film-forming properties of the inorganic layer 5 at each position in step S14, thereby improving the yield of the display device 1.

[0141] Next, a step of forming the quantum dot layer 33 is performed. In this embodiment, too, an example of a method of forming the red quantum dot layer 33R, the green quantum dot layer 33G, and the blue quantum dot layer 33B in this order in the step of forming the quantum dot layer 33 will be described.

[0142] In the process of forming the quantum dot layer 33 according to this embodiment, first, a quantum dot material containing a precursor 81 of the first inorganic material 4 and a plurality of quantum dots is ejected (step S15). For example, in step S15 in the process of forming the red quantum dot layer 33R, the quantum dot material is ejected by an inkjet method or the like onto a position overlapping the anode 31 corresponding to the red sub-pixel SPR in a planar view of the substrate 2 and between the banks 6. The quantum dot material contains the precursor 81 and the red quantum dots QDR. As a result, as shown in step S15-1 of FIG. 15 , a red quantum dot material layer 8R is formed at a position overlapping the anode 31 corresponding to the red sub-pixel SPR in a planar view of the substrate 2.

[0143] As described above, the quantum dots in the quantum dot layer 33 have different emission colors depending on the subpixel. Therefore, from the viewpoint of reducing color mixing between adjacent light-emitting elements, the amount of quantum dot material ejected in step S15 may be minimized to prevent the ejected quantum dot material from overflowing the bank 6. Furthermore, in step S15, at least a portion of the inorganic layer 5 that comes into contact with the ejected quantum dot material may be dissolved in the quantum dot material.

[0144] Following step S15, the quantum dot material layer is heated (step S16). Step S16 may be performed in the same manner as step S11 described above. For example, in step S16 in the process of forming the red quantum dot layer 33R, the red quantum dot layer 33R is formed on the inorganic layer 5 at a position corresponding to the red sub-pixel SPR, as shown in step S16-1 in FIG.

[0145] The above-described steps S15 and S16 are repeatedly performed until quantum dot layers of all luminescent colors are formed. For example, in this embodiment, the step of forming the green quantum dot layer 33G is performed after the step of forming the red quantum dot layer 33R.

[0146] For example, in step S15 of the process of forming the green quantum dot layer 33G, a quantum dot material containing a precursor 81 and green quantum dots QDG is discharged to a position overlapping with the anode 31 corresponding to the green sub-pixel SPG in plan view of the substrate 2 and between the banks 6. As a result, a green quantum dot material layer 8G is formed at a position overlapping with the anode 31 corresponding to the green sub-pixel SPG in plan view of the substrate 2, as shown in step S15-2 of FIG.

[0147] 16 , the green quantum dot layer 33G is formed on the inorganic layer 5 at a position corresponding to the green sub-pixel SPG by heating the green quantum dot material layer 8G in step S16 of the process of forming the green quantum dot layer 33G, as shown in step S16-2 of FIG. It should be noted that, in step S16 of the process of forming the green quantum dot layer 33G, the red quantum dots QDR of the red quantum dot layer 33R are also protected by the first inorganic material 4. Therefore, the first inorganic material 4 can reduce deterioration of the red quantum dot QDR due to heating of the green quantum dot material layer 8G.

[0148] Subsequently, steps S15 and S16 are performed in the same manner as described above, thereby forming a blue quantum dot layer 33B on the inorganic layer 5 at a position corresponding to the blue sub-pixel SPB, as shown in step S16-3 of FIG. In this manner, the quantum dot layer 33 is formed. Note that even during the process of forming the blue quantum dot layer 33B, the red quantum dots QDR and the green quantum dots QDG are protected by the first inorganic material 4. Therefore, the first inorganic material 4 can reduce the influence of the process of forming the blue quantum dot layer 33B on the red quantum dots QDR and the green quantum dots QDG.

[0149] As described above, in the example of the method for manufacturing the display device 1 according to this embodiment, the quantum dot layer 33 is formed by individually discharging a material containing quantum dots at positions corresponding to each subpixel. Therefore, in the example of the method for manufacturing the display device 1 according to this embodiment, the step of patterning the quantum dot material layer is not necessary. Therefore, the method for manufacturing the display device 1 according to this embodiment can eliminate steps that may deteriorate the quantum dots in the formed quantum dot layer 33, such as patterning and peeling of the photosensitive resin layer 7, and can improve the luminous efficiency and yield of the light-emitting element.

[0150] In step S15 of the manufacturing method for the display device 1 according to the present embodiment, a process of discharging a material containing the precursor 81 of the first inorganic material 4 and quantum dots at positions corresponding to each subpixel has been described as an example, but the present embodiment is not limited to this. For example, in the present embodiment, a material containing the first inorganic material 4 and quantum dots may be discharged in step S15 to directly form the quantum dot layer 33. In this case, step S16 may be omitted.

[0151] Following the formation of the quantum dot layer 33, the above-described steps S12 and S13 are performed to form the electron transport layer 34 and the cathode 35, completing the formation of the light-emitting element layer 3 shown in Fig. 13 and completing the manufacturing process of the display device 1. Note that in step S12, the electron transport layer 34 may be formed by individually ejecting the material for the electron transport layer 34 by an inkjet method or the like onto each quantum dot layer 33 and between the banks 6 in a plan view of the substrate 2.

[0152] <Leakage Current Reduction Mechanism According to Other Embodiments> The leakage current reduction mechanism in each light-emitting element of the display device 1 according to this embodiment will be described below, in comparison with display devices according to other comparative embodiments. Fig. 17 is a schematic cross-sectional side view 1701 of a display device 1B according to comparative embodiment 2 and a schematic cross-sectional side view 1702 of the display device 1 according to this embodiment.

[0153] FIG. 17 shows examples of display devices in which a misalignment occurs in the formation position of the blue quantum dot layer 33B during the manufacturing process of each display device. When forming the quantum dot layer 33 by discharging quantum dot material, for example, misalignment may occur in the position of the nozzle discharging the quantum dot material. Furthermore, when discharging the quantum dot material from the nozzle, clogging of the nozzle with quantum dots or precursors 81 may occur, resulting in a misalignment in the discharging speed or direction of the quantum dots from the nozzle. As a result, when forming the quantum dot layer 33 by discharging the quantum dot material, the formation position of the quantum dot layer 33 may be misaligned. As described above, when forming the quantum dot layer 33 by discharging the quantum dot material, the amount of material discharged may be minimized to reduce color mixing between adjacent light-emitting elements. In this case, the misalignment in the formation position of the quantum dot layer 33 may be significant.

[0154] When forming a light-emitting layer in which quantum dots are filled in the first inorganic material 4, as described above, the precursor 81 is reacted to form the first inorganic material 4, and therefore it is necessary to heat the material containing the precursor 81 at a high temperature. During this heating in the present embodiment, heat is likely to be applied to the substrate 2, which can easily cause, for example, misalignment of the substrate 2 with respect to the nozzle position that ejects the coating material. Furthermore, in the present embodiment, nozzle clogging with the precursor 8 is likely to occur when coating the material for the quantum dot material layer. Even in such cases, according to the present disclosure, it is possible to effectively reduce the leakage current described below and suppress a decrease in the luminous efficiency of each light-emitting element.

[0155] Figure 17 shows an example in which, due to a misalignment in the formation position of the blue quantum dot layer 33B, there is a position in each display device where the anode 31 of the blue sub-pixel SPB and the blue quantum dot layer 33B do not overlap in a planar view of the substrate 2.

[0156] Unlike the display device 1 according to the present embodiment, the display device 1B according to Comparative Example 2 does not include the inorganic layer 5. Therefore, if the formation position of the quantum dot layer 33 is shifted in the display device 1B, a portion where the hole transport layer 32 and the electron transport layer 34 come into contact with each other may be generated. At this position, as shown in the schematic side cross-sectional view 1701 of the display device 1B in FIG. 17 , a leakage current LC5 may flow from the anode 31 to the cathode 35 without passing through the quantum dot layer 33. Therefore, if the formation position of the quantum dot layer 33 is shifted during the manufacturing process of the display device 1B, the luminous efficiency of each light-emitting element of the display device 1B may decrease.

[0157] On the other hand, the display device 1 according to this embodiment includes an inorganic layer 5. Therefore, even if the quantum dot layer 33 is misaligned, the contact area between the electron transport layer 34 and the inorganic layer 5 may increase, but the contact area between the hole transport layer 32 and the electron transport layer 34 is not formed. Therefore, as shown in the schematic side cross-sectional view 1702 of the display device 1 in FIG. 17 , the inorganic layer 5 reduces the leakage current LC6 that would otherwise flow from the anode 31 through the hole transport layer 32 and bypass the quantum dot layer 33 to the electron transport layer 34 and the cathode 35. Therefore, even in this embodiment, the display device 1 reduces the intensity of the leakage current and suppresses a decrease in the luminous efficiency of each light-emitting element, regardless of the misalignment of the quantum dot layer 33.

[0158] <Mechanism for reducing leakage current due to misalignment of bank formation position> Another mechanism for reducing leakage current in each light-emitting element of display device 1 according to this embodiment will be described below, in comparison with a display device according to a comparative embodiment. Figure 18 is a schematic cross-sectional side view 1801 of display device 1B according to comparative embodiment 2 and a schematic cross-sectional side view 1802 of display device 1 according to this embodiment.

[0159] 18 shows examples of display devices in which a deviation occurs in the formation position of the bank 6 between the green light-emitting element 3G and the blue light-emitting element 3B during the manufacturing process of each display device. In particular, in this embodiment, the formation position of the bank 6 is shifted so as to be closer to the green sub-pixel SPG. In this case, even if there is no deviation in the discharge position of the quantum dot material during the process of forming the blue quantum dot layer 33B, the material may not sufficiently wet and spread between the banks 6.

[0160] Therefore, if the formation position of the bank 6 is shifted in the display device 1B, a portion may be formed where the hole transport layer 32 and the electron transport layer 34 come into contact with each other. At this position, as shown in the schematic side cross-sectional view 1801 of the display device 1B in Fig. 18 , a leakage current LC7 may flow from the anode 31 to the cathode 35 without passing through the quantum dot layer 33. Therefore, even if the formation position of the bank 6 is shifted during the manufacturing process of the display device 1B, the luminous efficiency of each light-emitting element of the display device 1B may decrease.

[0161] On the other hand, the display device 1 according to this embodiment includes an inorganic layer 5. Therefore, if the bank 6 is misaligned, the contact area between the electron transport layer 34 and the inorganic layer 5 may increase, but the hole transport layer 32 and the electron transport layer 34 will not be in contact with each other. As a result, as shown in the schematic side cross-sectional view 1802 of the display device 1 in FIG. 18 , the inorganic layer 5 reduces the leakage current LC8 that would otherwise flow from the anode 31 through the hole transport layer 32 and bypass the quantum dot layer 33 to the electron transport layer 34 and the cathode 35. Therefore, in this embodiment as well, the display device 1 reduces the intensity of the leakage current that occurs, regardless of the misalignment of the bank 6, and suppresses a decrease in the luminous efficiency of each light-emitting element.

[0162] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0163] REFERENCE SIGNS LIST 1 Display device 2 Substrate 3R Red light-emitting element 3G Green light-emitting element 3B Blue light-emitting element 4 First inorganic material 5 Inorganic layer 6 Bank 31 Anode (first electrode) 32 Hole transport layer (charge transport layer) 33 Quantum dot layer 34 Electron transport layer (charge transport layer) 35 Cathode (second electrode)

Claims

1. A substrate, a first electrode and a second electrode, and a quantum dot layer located between the first electrode and the second electrode and having a plurality of quantum dots and a first inorganic material filling between the plurality of quantum dots, and a plurality of light-emitting elements on the substrate including the same, an inorganic layer located between at least two of the light-emitting elements and including a second inorganic material having a band gap of 2.8 eV or more, a semiconductor or an insulator, a display device provided with the same.

2. The display device according to claim 1, wherein a part of the inorganic layer is located between the first electrode and the second electrode of the light-emitting element.

3. The plurality of light-emitting elements further include a charge transport layer located at least one of between the first electrode and the quantum dot layer and between the second electrode and the quantum dot layer, the inorganic layer is in contact with at least any one of the charge transport layers, The display device according to claim 1, wherein the band gap of the second inorganic material is equal to or greater than the band gap of the charge transport layer with which the inorganic layer is in contact.

4. The display device according to claim 3, wherein the band gap of the second inorganic material has a difference of 0.2 eV or more from the band gap of the charge transport layer with which the inorganic layer is in contact.

5. The charge transport layer includes a first charge transport layer located between the first electrode and the quantum dot layer and a second charge transport layer located between the second electrode and the quantum dot layer, The display device according to claim 3, wherein at least a part of the inorganic layer is located between the first charge transport layer and the second charge transport layer.

6. Further provided with a bank partitioning between the plurality of light-emitting elements, The display device according to claim 5, wherein at least a part of the inorganic layer is located between any one of the charge transport layers and the bank.

7. The display device according to any one of claims 1 to 6, wherein at least a part of the inorganic layer overlaps with the periphery of the quantum dot layer in a plan view of the substrate.

8. The display device according to any one of claims 1 to 6, wherein at least a part of the inorganic layer overlaps with the first electrode in a plan view of the substrate.

9. The display device according to any one of claims 1 to 6, wherein a part of the inorganic layer overlaps with the quantum dot layer in a plan view of the substrate.

10. The display device according to claim 9, wherein the thickness of the inorganic layer in contact with the quantum dot layer is smaller than the thickness of the inorganic layer overlapping with the periphery of the quantum dot layer in a plan view of the substrate.

11. The display device according to any one of claims 1 to 6, wherein the inorganic layer is formed only at a position overlapping with the periphery of the quantum dot layer in a plan view of the substrate.

12. The display device according to any one of claims 1 to 6, wherein the first inorganic material and the second inorganic material include the same inorganic material.

13. The display device according to any one of claims 1 to 6, wherein the first inorganic material and the second inorganic material include zinc sulfide or magnesium zinc sulfide.

14. The display device according to any one of claims 1 to 6, wherein the inorganic layer includes aluminum oxide.

15. The display device according to any one of claims 1 to 6, wherein the film thickness of the inorganic layer is 1 nm or more and 30 nm or less.

16. The display device according to claim 15, wherein the film thickness of the inorganic layer is 1 nm or more and 2 nm or less.

17. Preparation of a substrate, Formation of a plurality of first electrodes on the substrate, formation of a plurality of quantum dot layers having a plurality of quantum dots and a first inorganic material filling between the plurality of quantum dots at positions overlapping with each of the first electrodes in a plan view of the substrate, and formation of at least one second electrode at a position overlapping with each of the first electrodes in a plan view of the substrate, including formation of a plurality of light-emitting elements, A method for manufacturing a display device, including formation of an inorganic layer located between at least two of the light-emitting elements and including a second inorganic material having a semiconductor or insulator with a band gap of 2.8 eV or more.

18. The formation of the inorganic layer includes film formation of the inorganic layer including the second inorganic material at a position overlapping with at least any one of the first electrodes in a plan view of the substrate, The method for manufacturing a display device according to claim 17, wherein the formation of the quantum dot layer includes film formation of a quantum dot material layer having the first inorganic material and a plurality of the quantum dots on the inorganic layer.

19. The formation of a plurality of the light-emitting elements further includes formation of a charge transport layer on at least the first electrode, The method for manufacturing a display device according to claim 18, wherein the formation of the inorganic layer includes film formation of the inorganic layer on the charge transport layer.

20. The method of manufacturing a display device according to claim 18, wherein in forming the quantum dot material layer, at least a part of the inorganic layer in contact with the quantum dot material layer dissolves in the quantum dot material layer.

21. The method of manufacturing a display device according to any one of claims 18 to 20, wherein the formation of the quantum dot layer further includes patterning the quantum dot material layer.

22. Furthermore, it includes forming a bank that partitions between the plurality of first electrodes, The method of manufacturing a display device according to any one of claims 18 to 20, wherein the formation of the quantum dot layer includes discharging a quantum dot material including the first inorganic material or a precursor of the first inorganic material and the plurality of quantum dots between the banks in a plan view of the substrate.

23. A substrate, a first electrode and a second electrode; a plurality of light-emitting elements on the substrate, including a quantum dot layer having a plurality of quantum dots and a first inorganic material, located between the first electrode and the second electrode; A display device comprising: an inorganic layer including a second inorganic material having a semiconductor or insulator with a band gap of 2.8 eV or more, located between at least two of the light-emitting elements.