Quantum dot dispersion, light-emitting element, display device, and method for manufacturing light-emitting element

Abstract

A light-emitting element (10) includes an anode (2), a cathode (5), and a light-emitting layer (EML) provided between the anode (2) and the cathode (5) and containing quantum dots (QD). The light-emitting layer (EML) contains an oxide of Si element as an adduct (XO) of quantum dots (QD), and the oxide contains a Si-O-Na bond partially.

Description

Quantum dot dispersion, light-emitting element, display device, and method for manufacturing light-emitting element

[0001] The present disclosure relates to a quantum dot dispersion, a light-emitting device, a display device, and a method for manufacturing the light-emitting device.

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

[0003] For example, in Patent Document 1, quantum dots are formed by SiO ２ It is described that the oxide is protected by the above-mentioned method.

[0004] Japanese Patent Application Publication No. 2021-182025

[0005] However, the quantum dots described in Patent Document 1 are made of SiO ２ In the technology of protecting with oxides such as those mentioned above, hydroxyl groups (-OH) are generated in part of the oxide, and in the case of a quantum dot dispersion, the quantum dots may aggregate due to dehydration condensation between the hydroxyl groups (-OH), and in the case of a light-emitting element, there is a problem that the light-emitting element may be deteriorated due to water generated by dehydration condensation between the hydroxyl groups (-OH).

[0006] An aspect of the present disclosure aims to provide a dispersion of quantum dots that is more stable in that the quantum dots protected by an oxide are prevented from aggregating with each other; a light-emitting element that includes a light-emitting layer that prevents water generation due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots; a method for manufacturing the light-emitting element; and a display device that includes the light-emitting element.

[0007] In order to solve the above-mentioned problems, the quantum dot dispersion of the present disclosure comprises quantum dots containing an oxide of element X as an additive, and a dispersion medium, wherein the oxide partially contains at least one of an X-O-M1 bond (where O is an oxygen element, M1 is any element belonging to the alkali metals, and X is the element X that is contained in the oxide in a greater amount than M1 and that constitutes the skeleton of the oxide together with the oxygen element) and an X-O-M2-O-X bond (where O is an oxygen element, M2 is any element belonging to the alkaline earth metals, and X is the element X that is contained in the oxide in a greater amount than M2 and that constitutes the skeleton of the oxide together with the oxygen element).

[0008] In order to achieve the above object, the light-emitting device of the present disclosure includes an anode, a cathode, and a light-emitting layer provided between the anode and the cathode and including quantum dots, wherein the light-emitting layer includes an oxide of an element X as an additive of the quantum dots or a matrix filling at least a portion of the gaps between the quantum dots, and the oxide includes at least one of an X-O-M1 bond (where O is an oxygen element, M1 is any element belonging to alkali metals, and X is the element X that is contained in the oxide in a greater amount than M1 and that constitutes the skeleton of the oxide together with the oxygen element) and an X-O-M2-O-X bond (where O is an oxygen element, M2 is any element belonging to alkaline earth metals, and X is the element X that is contained in the oxide in a greater amount than M2 and that constitutes the skeleton of the oxide together with the oxygen element).

[0009] In order to solve the above-mentioned problems, the display device of the present disclosure includes a plurality of the light-emitting elements, wherein the plurality of light-emitting elements include a first light-emitting element including a first light-emitting layer that emits light in a first light-emitting color as the light-emitting layer, and a second light-emitting element including a second light-emitting layer that emits light in a second light-emitting color having an emission peak wavelength on the shorter wavelength side than the emission peak wavelength of the first light-emitting color, at least one of the first light-emitting layer and the second light-emitting layer includes M1 and M2, and a ratio of the number of M1 to the number of M2 per unit volume of the first light-emitting layer is different from a ratio of the number of M1 to the number of M2 per unit volume of the second light-emitting layer.

[0010] In order to solve the above-mentioned problems, the manufacturing method of the light-emitting element of the present disclosure includes a step of forming a light-emitting layer including a plurality of quantum dots and an oxide of element X, and in the step of forming the light-emitting layer, the oxide is formed which includes at least one of an X-O-M1 bond (O is an oxygen element, M1 is any element belonging to alkali metals, X is the element X which is contained in the oxide in a larger amount than M1 and which constitutes the skeleton of the oxide together with the oxygen element) and an X-O-M2-O-X bond (O is an oxygen element, M2 is any element belonging to alkaline earth metals, X is the element X which is contained in the oxide in a larger amount than M2 and which constitutes the skeleton of the oxide together with the oxygen element).

[0011] According to one aspect of the present disclosure, it is possible to provide a dispersion of quantum dots that is more stable in that the quantum dots protected by an oxide are prevented from aggregating with each other, a light-emitting element that includes a light-emitting layer that prevents water generation due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots, a method for manufacturing the light-emitting element, and a display device that includes the light-emitting element.

[0012] 1. It is a plan view showing a schematic configuration of a display device of embodiment 1. It is a cross-sectional view showing a schematic configuration of a light-emitting element provided in the display device of embodiment 1. It is a view showing a schematic configuration of a light-emitting layer provided in the light-emitting element shown in FIG. 2. It is a view showing a schematic configuration of another light-emitting layer that can be provided in the light-emitting element shown in FIG. 2. It is a cross-sectional view showing a schematic configuration of the light-emitting layer shown in FIG. 3. It is a view showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting element shown in FIG. 2. It is a cross-sectional view showing a schematic configuration of one form of the light-emitting layer shown in FIGS. 6 and 7. It is a cross-sectional view showing a schematic configuration of another form of the light-emitting layer shown in FIGS. 6 and 7. It is a cross-sectional view showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting element shown in FIG. 2. It is a view showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting element shown in FIG. 2. It is a view for explaining a method for manufacturing the light-emitting element shown in FIG. 2. It is a view showing an example of a step of forming a light-emitting layer in a method for manufacturing the light-emitting element shown in FIG. 13. It is a view showing another example of a step of forming a light-emitting layer in a method for manufacturing the light-emitting element shown in FIG. 13. It is a view showing yet ... 21 is a diagram showing a schematic configuration of still another light-emitting layer that can be provided in the light-emitting element shown in Fig. 2. FIG. 17 is a diagram showing an example of a process for forming the light-emitting layer shown in Fig. 17. FIG. 18 is a diagram showing another example of a process for forming the light-emitting layer shown in Fig. 17. FIG. 19 is a diagram showing yet another example of a process for forming the light-emitting layer shown in Fig. 17. FIG. 20 is a diagram showing a schematic configuration of still another light-emitting layer that can be provided in the light-emitting element shown in Fig. 2. R contained in the light-emitting layer shown in Fig. 21 １ group, R ２ Groups and R ３ 1 is a diagram showing a preferred example of each group. FIG. 2 is a diagram showing a schematic configuration of a light-emitting layer provided in a light-emitting device that is a comparative example.

[0013] The following describes embodiments of the present disclosure with reference to Figures 1 to 23. For the sake of convenience, components having the same functions as those described in specific embodiments will be denoted by the same reference numerals, and descriptions thereof may be omitted.

[0014] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0015] As shown in Fig. 1, the display device 1 includes a frame area NDA and a display area DA. The display area DA of the display device 1 includes a plurality of pixels PIX, each of which includes a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP. In this embodiment, a case in which one pixel PIX is configured with a red subpixel RSP, a green subpixel GSP, and a blue subpixel BSP will be described as an example, but this is not limiting. For example, one pixel PIX may include subpixels of other colors in addition to the red subpixel RSP, the green subpixel GSP, and the blue subpixel BSP.

[0016] FIG. 2 is a cross-sectional view showing a schematic configuration of the light-emitting element 10 provided in the display device 1 of the first embodiment.

[0017] The red sub-pixel RSP provided in the display area DA of the display device 1 shown in FIG. 1 includes a red light-emitting element in which the emitting layer EML in the light-emitting element 10 shown in FIG. 2 is a red light-emitting layer, the green sub-pixel GSP provided in the display area DA of the display device 1 shown in FIG. 1 includes a green light-emitting element in which the emitting layer EML in the light-emitting element 10 shown in FIG. 2 is a green light-emitting layer, and the blue sub-pixel BSP provided in the display area DA of the display device 1 shown in FIG. 1 includes a blue light-emitting element in which the emitting layer EML in the light-emitting element 10 shown in FIG. 2 is a blue light-emitting layer.

[0018] The light-emitting element 10 includes an anode 2, a cathode 5, and an emitting layer EML between the anode 2 and the cathode 5, the emitting layer EML including quantum dots (QDs). In this embodiment, the light-emitting element 10 includes a hole functional layer 3 between the anode 2 and the emitting layer EML, and an electronic functional layer 4 between the cathode 5 and the emitting layer EML. However, the present invention is not limited to this. The hole functional layer 3 may be composed of only a hole transport layer (HTL), or may be composed of only a hole injection layer (HIL). Alternatively, the hole injection layer (HIL) and the hole transport layer (HTL) may be stacked in this order from the anode 2 side, or may be omitted as appropriate. The hole injection layer (HIL) can be formed using, for example, a composite (PEDOT:PSS) of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS). The hole transport layer (HTL) may be formed using an organic material such as poly[(9,9-dioctylfluorenyl-2,7-diyl)-co-(4,4'-(N-(4-sec-butylphenyl))diphenylamine)] (TFB), N,N'-bis(4-butylphenyl)-N,N'-bis(phenyl)-benzidine (poly-TPD), or polyvinylcarbazole (PVK), or may be formed using an inorganic material such as NiO or NiO nanoparticles. The electronic functional layer 4 may be composed of only an electron transport layer (ETL), or may be composed of only an electron injection layer (EIL), or may be a layer in which the electron transport layer (ETL) and the electron injection layer (EIL) are stacked in this order from the anode 2 side, or may be omitted as appropriate. The electron transport layer (ETL) may be formed using an organic material such as 2,2′,2″-(1,3,5-benzinetriyl)-tris(1-phenyl-1-H-benzimidazole) (TPBi), or an inorganic material such as ZnO, an oxide containing Zn and Mg, ZnO nanoparticles, or nanoparticles of an oxide containing Zn and Mg.The electron injection layer (EIL) may be formed using, for example, an alkali metal or alkaline earth metal such as aluminum, strontium, calcium, lithium, cesium, magnesium oxide, aluminum oxide, strontium oxide, lithium oxide, lithium fluoride, magnesium fluoride, strontium fluoride, calcium fluoride, barium fluoride, cesium fluoride, polymethyl methacrylate polystyrene sodium sulfonate, or the like; an oxide of an alkali metal or alkaline earth metal; a fluoride of an alkali metal or alkaline earth metal; or an organic complex of an alkali metal.

[0019] The quantum dots QDs included in the light-emitting layer EML may have, for example, a core structure, a core / shell structure, a core / shell / shell structure, or a shell structure with a continuously changing core / shell ratio. The shell may cover a portion of the core, but it is more preferable for the shell to completely cover the core. The core material of the quantum dots QDs may be, for example, a II-VI group semiconductor crystal such as MgS, MgSe, MgTe, CaS, CaSe, CaTe, BaS, BaSe, BaTe, ZnS, ZnSe, ZnTe, CdS, CdSe, CdTe, PbS, PbSe, HgS, HgSe, or HgTe; a III-V group semiconductor crystal such as GaAs, GaP, InN, InAs, InP, or InSb; or Ga ３ S ２ , Ga ２ Se ３ , In ２ S ３ , In ２ Se ３ Crystals of III-VI group semiconductors such as CuInGaS, AgInGaS, CuInGaS, AgInGaZnS, CuInGaSe, AgInGaSe, etc., crystals of I-III-VI group semiconductors such as C and Si, crystals of IV group semiconductors such as CsPbI ３ , CsPbBr ３ , CsPbCl ３ The shell material can be made of a semiconductor crystal with a perovskite structure such as the above. The shell material is selected from the same material group as the core material, and is preferably one that has a lattice constant close to that of the core material and a larger band gap than the core material.

[0020] 2 may be a top-emission type or a bottom-emission type. The light-emitting element 10 has a forward-laid structure in which the cathode 5 is disposed as an upper layer than the anode 2. To form the light-emitting element 10 as a top-emission type, the anode 2 may be formed from an electrode material that reflects visible light, and the cathode 5 may be formed from an electrode material that transmits visible light. To form the light-emitting element 10 as a bottom-emission type, the anode 2 may be formed from an electrode material that transmits visible light, and the cathode 5 may be formed from an electrode material that reflects visible light.

[0021] The electrode material that reflects visible light is not particularly limited as long as it can reflect visible light and has electrical conductivity. Examples of the electrode material that reflects visible light include metal materials such as Al, Mg, Li, and Ag, alloys of the metal materials, laminates of the metal materials and transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), and laminates of the alloys and the transparent metal oxides.

[0022] On the other hand, the electrode material that transmits visible light is not particularly limited as long as it can transmit visible light and has conductivity, and examples thereof include transparent metal oxides (e.g., indium tin oxide, indium zinc oxide, indium gallium zinc oxide, etc.), thin films made of metal materials such as Al and Ag, and nanowires made of metal materials such as Al and Ag.

[0023] Fig. 3 is a diagram showing a schematic configuration of the emitting layer EML provided in the light-emitting element 10 shown in Fig. 2. Fig. 4 is a diagram showing a schematic configuration of another emitting layer EML1 that can be provided in the light-emitting element 10 shown in Fig. 2. Fig. 23 is a diagram showing a schematic configuration of an emitting layer EML' provided in a light-emitting element that is a comparative example.

[0024] As shown in Figure 23, the light-emitting layer EML' provided in the comparative light-emitting device contains an oxide of Si (silicon oxide) as an adduct XO' located at least partially around the quantum dots QD. The adduct XO' may be chemically bonded to the quantum dots QD via an organic element, or may be chemically bonded directly to the quantum dots QD, and may be formed with a uniform thickness around the quantum dots QD, or may be formed with a non-uniform thickness around the quantum dots QD. The oxide of Si (silicon oxide) contains a large number of hydroxyl groups (-OH). In the case of the comparative light-emitting device provided with the light-emitting layer EML', there is a problem in that the light-emitting device deteriorates due to water generated by dehydration condensation between the hydroxyl groups (-OH).

[0025] The emitting layers EML and EML1 shown in Figures 3 and 4 contain an oxide of element X as the quantum dot QD adduct XO and XO1. In this embodiment, the emitting layers EML and EML1 contain Si as the element X and an oxide of Si (silicon oxide) as the quantum dot QD adduct XO and XO1, as an example. However, the present invention is not limited to this. The emitting layers EML and EML1 may contain, as the quantum dot QD adduct XO and XO1, oxides such as an oxide of Al (aluminum oxide), an oxide of Ti (titanium oxide), and an oxide of Zr (zirconium oxide). When the quantum dot QD adduct XO and XO1 contains an oxide of Si (silicon oxide), a high quantum dot QD protection effect can be achieved, thereby suppressing deterioration of the quantum dot QD due to water, oxygen, etc., and realizing a light-emitting device 10 with improved reliability.

[0026] The oxide of the element X partially contains an X-O-M1 bond. Here, O is oxygen, M1 is any element belonging to the alkali metals, and X is contained in the oxide in a greater amount than M1 and is an element that constitutes the skeleton of the oxide together with the oxygen element. In the case of the emitting layer EML shown in FIG. 3 , the oxide of Si element (silicon oxide) contained as the additive XO of the quantum dots QDs contains Na as the element M1 and therefore partially contains Si-O-Na bonds. Si is contained in the oxide in a greater amount than Na and is an element that constitutes the skeleton of the oxide together with the oxygen element. In the case of the emitting layer EML1 shown in FIG. 4 , the oxide of Si element (silicon oxide) contained as the additive XO1 of the quantum dots QDs contains K as the element M1 and therefore partially contains Si-O-K bonds. Si is contained in the oxide in a greater amount than K and is an element that constitutes the skeleton of the oxide together with the oxygen element. Although not shown, when the oxide of element Si (silicon oxide) contained as an adduct of quantum dots QD contains Li as the element M1, it partially contains Si-O-Li bonds, and Si is contained in the oxide in greater amounts than Li and is an element that constitutes the skeleton of the oxide together with oxygen. This configuration makes it possible to realize a light-emitting device 10 including emitting layers EML / EML1 that suppress the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QD. The oxide refers to an oxide in which at least a portion of the X element is bonded to three or more —O—X groups, forming a network of bonds between the X element and the O element. For example, as shown in FIGS. 3 and 4 , the oxide of element Si as the adduct XO / XO1 of quantum dots QD has at least a portion of the Si element bonded to three or more —O—Si groups, forming a network of bonds between the Si element and the O element. Furthermore, the quantum dots QD containing an oxide of Si as the adduct XO or XO1 shown in FIGS. 3 and 4 may have an organic moiety, such as an organic ligand, outside the oxide of Si that is the adduct XO or XO1, although this organic moiety may be, for example, coordinately bonded or covalently bonded to the oxide of Si that is the adduct XO or XO1.

[0027] The presence of the X-O-M1 bond may be confirmed by observing fragments containing O-M1 using, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) or XPS. The presence of an oxide of Si element may be confirmed by a combination of TEM and EDX or by IR.

[0028] The oxide of element X that is the adduct XO or XO1 is preferably an insulator, and in this embodiment, a case in which the quantum dots QD contain an oxide of element Si (silicon oxide) as the adduct XO or XO1 will be described as an example, but the present invention is not limited to this. As described above, by making the oxide of element X that is the adduct XO or XO1 of the quantum dots QD an insulator, it is possible to suppress current flow in the emitting layers EML or EML1 via the adduct XO or XO1 of the quantum dots QD without passing through the quantum dots QD, and a light-emitting element 10 with higher luminous efficiency can be realized.

[0029] When the oxide of element X contains an X-O-M1 bond, the emitting layers EML and EML1 contain the M1 compound. For example, as shown in FIG. 3, when the oxide (silicon oxide) of element Si, which is the adduct XO of quantum dots QDs, contains an X-O-Na bond, the emitting layer EML contains, for example, NaCl or NaOH as the Na compound. As shown in FIG. 4, when the oxide (silicon oxide) of element Si, which is the adduct XO1 of quantum dots QDs, contains an X-O-K bond, the emitting layer EML1 contains, for example, KCl or KOH as the K compound. Although not shown, when the oxide (silicon oxide) of element Si, which is the adduct of quantum dots QDs, contains an X-O-Li bond, the emitting layer contains, for example, LiCl or LiOH as the Li compound. Note that the M1 compound contained in the emitting layers EML and EML1 is not limited to a chloride or hydroxide and may be, for example, a halide or a salt of a weak acid.

[0030] It is preferable that the value of ((the number of any element belonging to the alkali metals) / (the number of element X))×100% in the light-emitting layer, i.e., the value of ((the number of Na elements) / (the number of Si elements))×100% in the light-emitting layer EML shown in FIG. 3 and the value of ((the number of K elements) / (the number of Si elements))×100% in the light-emitting layer EML1 shown in FIG. 4 , are 0.1% or more and 10% or less. As described above, by setting the content of any element belonging to the alkali metals in the light-emitting layer relative to element X, which is contained in the oxide in a larger amount than any element belonging to the alkali metals and which constitutes the skeleton of the oxide together with element oxygen, within the above-mentioned predetermined range, it is possible to realize a light-emitting device 10 having a light-emitting layer with higher stability.

[0031] In the oxide of X element that is the adduct XO or XO1 of the quantum dots QD, the number of O-M1 groups is preferably larger than the number of O-H groups. That is, in the oxide of Si element (silicon oxide) that is the adduct XO of the quantum dots QD shown in Figure 3, the number of O-Na groups is preferably larger than the number of O-H groups, and in the oxide of Si element (silicon oxide) that is the adduct XO1 of the quantum dots QD shown in Figure 4, the number of O-K groups is preferably larger than the number of O-H groups. This configuration makes it possible to realize a light-emitting device 10 that includes emitting layers EML or EML1 that further suppress the generation of water due to dehydration condensation between hydroxyl groups (-OH) in the oxide that protects the quantum dots QD.

[0032] The thickness of a portion of the oxide of the X element, which is the quantum dot QD adduct XO / XO1, provided between adjacent first and second quantum dots QDs among the multiple quantum dots QDs included in the emitting layers EML / EML1 shown in Figures 3 and 4, is preferably 5 nm or less. Note that the thickness of the portion of the oxide of the X element, which is the quantum dot QD adduct XO / XO1, may be one atomic layer or more and 5 nm or less. With this configuration, the content of the oxide of the X element, which is the quantum dot QD adduct XO / XO1, that does not contribute to light emission, can be reduced in the emitting layers EML / EML1.

[0033] In the emitting layers EML and EML1 shown in FIGS. 3 and 4, the oxide of element X, which is the adduct XO and XO1 of the quantum dots QD contained in the emitting layers EML and EML1, is represented by X—(CH ２ )n-L bonds will be described as an example. Here, X is the element X, C is a carbon element, H is a hydrogen element, n is a natural number, and L is a group capable of bonding to or coordinating with the quantum dots QDs. Without being limited thereto, as will be described later with reference to FIGS. 6, 7, 8, 9, and 10, the oxide of element X, which is an adduct of quantum dots QDs contained in the light-emitting layer, may not contain a group capable of bonding to or coordinating with the quantum dots QDs. In this case, the oxide of element X, which is an adduct of quantum dots QDs contained in the light-emitting layer, functions as a matrix. In this embodiment, quantum dots QDs having a core / shell structure with a shell formed of ZnS are used, and sulfur (S) is used as a group capable of bonding to or coordinating with the shell of the quantum dots QDs made of ZnS. Therefore, as shown in FIGS. 3 and 4, the oxide of Si, which is an adduct of quantum dots QDs XO and XO1 contained in the light-emitting layers EML and EML1, is a Si-(CH ２ ) ３ The sulfur element is a group that can be bonded to or coordinated with the shell of the quantum dot QD, and contains a -S bond as a part of it. In addition to the sulfur element (S) described above, groups that can be bonded to or coordinated with the shell of the quantum dot QD made of ZnS include, for example, an NH group, a COO group, and a PH group. These groups include a thiol group (-SH), an amine group (-NH ２ ), a carboxylic acid group (—COOH) and a phosphine group (—PH ２ ) can remove one hydrogen atom to form a group capable of bonding or coordinating. With this configuration, the oxide of element X, which is an additive of the quantum dots QD contained in the light-emitting layer, is bonded to or coordinated with the quantum dots QD, thereby achieving a high protection effect for the quantum dots QD, thereby realizing a light-emitting element 10 with improved reliability.

[0034] Fig. 5 is a cross-sectional view showing a schematic configuration of the emitting layer EML shown in Fig. 3. Figs. 6 and 7 are views showing a schematic configuration of yet another emitting layer EML2 that can be provided in the light-emitting device 10 shown in Fig. 2. Fig. 8 is a cross-sectional view showing a schematic configuration of one embodiment of the emitting layer EML2 shown in Figs. 6 and 7. Fig. 9 is a cross-sectional view showing a schematic configuration of another embodiment of the emitting layer EML2 shown in Figs. 6 and 7. Fig. 10 is a cross-sectional view showing a schematic configuration of yet another emitting layer EML3 that can be provided in the light-emitting device 10 shown in Fig. 2.

[0035] 3 and 4 , the above-described emitting layers EML and EML1 contain, as the quantum dot QD adducts XO and XO1, an oxide of element X bonded to or coordinated with the quantum dots QDs. Therefore, for example, by appropriately adjusting the amount of the quantum dot QD adduct XO to an extent that the surface of the quantum dots QDs is covered, the emitting layer EML can be formed into a shape that conforms to the shape of the quantum dots QDs, as shown in FIG. 5 . Without being limited thereto, the amount of the quantum dot QD adduct XO may be increased to fill at least a portion of the gaps between the quantum dots QDs containing the adduct XO shown in FIG. 5 . Furthermore, as in the emitting layer EML3 shown in FIG. 10 , at least a portion of the gaps between the quantum dots QDs containing the adduct XO may be filled with, for example, a matrix XO2, which is another adduct of the quantum dots QDs that does not contain a group capable of bonding to or coordinating with the quantum dots QDs. The emitting layers EML2 and EML3 shown in Figures 6, 7, 8, 9, and 10 contain, as a matrix XO2 that is an adduct of quantum dots QDs, an oxide of element X that is not bonded to or coordinated with the quantum dots QDs. In this case, the matrix XO2 that is an adduct of quantum dots QDs fills at least a portion of the gaps between the multiple quantum dots QDs. Note that the configuration of the oxide of element X that is the matrix XO2 that is an adduct of quantum dots QDs contained in the emitting layers EML2 and EML3 is the same as the oxide of element X that is the adduct of quantum dots QDs XO and XO1 contained in the emitting layers EML and EML1 described above, except that it does not contain any groups that can bond to or coordinate with the quantum dots QDs, and therefore a description thereof will be omitted here.

[0036] 6, the emitting layer EML2 includes a plurality of quantum dots QDA and QDB and a matrix XO2 that is an adduct of the quantum dots QDA and QDB formed so as to fill at least a portion of the gaps between the quantum dots QDA and QDB. The quantum dots QDA and QDB that constitute the quantum dot set P1 are spaced apart by a predetermined distance, and a gap is formed between the quantum dots QDA and QDB. An oxide of element X is formed as the matrix XO2 that does not include a group capable of bonding to or coordinating to the quantum dots QDA and QDB so as to fill at least a portion of this gap.

[0037] 7, in the emitting layer EML2, unlike in Fig. 6, there are also portions where the quantum dots QDA and QDB constituting the quantum dot set P2 are in contact with each other. In this case as well, a gap is formed between the quantum dot QDA and the quantum dot QDB, and an oxide of the element X is formed as a matrix XO2 that does not contain a group capable of bonding to or coordinating with the quantum dots QDA and QDB so as to fill at least a portion of this gap.

[0038] 6 and 7 , the thickness of a portion of the oxide of the X element, which is the matrix XO2 provided between adjacent first quantum dots QDA and second quantum dots QDB, is preferably 5 nm or less. Note that the thickness of the portion of the oxide of the X element, which is the matrix XO2, may be one atomic layer or more and 5 nm or less. With this configuration, the conductivity between the quantum dots QDA and QDB in the emitting layer EML2 is improved, thereby reducing the driving voltage of the light-emitting element 10.

[0039] As shown in Fig. 8, the emitting layer EML2 shown in Fig. 6 and Fig. 7 may include a matrix XO2 that is an addition of quantum dots QDs formed so as to completely fill the gaps between the plurality of quantum dots QDs, or may include a matrix XO2 that is an addition of quantum dots QDs formed so as to partially fill the gaps between the plurality of quantum dots QDs, that is, so that gaps DEF remain between the plurality of quantum dots QDs, as shown in Fig. 9. A light-emitting device 10 including such an emitting layer EML2 can also obtain the same effects as the light-emitting device 10 including the above-mentioned emitting layers EML and EML1.

[0040] Fig. 11 is a diagram showing a schematic configuration of an emitting layer EML4 that can be provided in the light-emitting element 10 shown in Fig. 2. Fig. 12 is a diagram showing a schematic configuration of an emitting layer EML5 that can be provided in the light-emitting element 10 shown in Fig. 2.

[0041] The emitting layers EML4 and EML5 contain an oxide of the element X as an adduct XO of the quantum dots QD. In this embodiment, as shown in Fig. 11 and Fig. 12 , the emitting layers EML4 and EML5 contain Si as the element X and an oxide of the Si element (silicon oxide) as an adduct XO4 and XO5 of the quantum dots QD.

[0042] The oxide of the element X partially contains an X-O-M2-O-X bond. Here, O is oxygen, M2 is any element belonging to the alkaline earth metal group, and X is contained in the oxide in a greater amount than M2 and is an element that constitutes the skeleton of the oxide together with the oxygen element. In the case of the emitting layer EML4 shown in FIG. 11 , the oxide of Si element (silicon oxide) contained as the quantum dot QD adduct XO4 contains Ca as the element M2 and therefore partially contains Si-O-Ca-O-Si bonds. Si is contained in the oxide in a greater amount than Ca and is an element that constitutes the skeleton of the oxide together with the oxygen element. In the case of the emitting layer EML5 shown in FIG. 12 , the oxide of Si element (silicon oxide) contained as the quantum dot QD adduct XO5 contains Mg as the element M2 and therefore partially contains Si-O-Mg-O-Si bonds. Si is contained in the oxide in a greater amount than Mg and is an element that constitutes the skeleton of the oxide together with the oxygen element. Although not shown, when the oxide of Si element (silicon oxide) contained as an adduct of the quantum dots QD contains Be as the element M2, it may contain Si-O-Be-O-Si bonds in part, and Si may be contained in the oxide in a larger amount than Be and may be an element that constitutes the skeleton of the oxide together with the oxygen element. With this configuration, it is possible to realize a light-emitting element 10 including emitting layers EML4 and EML5 that suppress the generation of water due to dehydration condensation between hydroxyl groups (-OH) in the oxide that protects the quantum dots QD.

[0043] The presence of the X-O-M2-O-X bond may be confirmed by observing a fragment containing -O-M2-O- using, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) or XPS. The presence of an oxide of Si element may be confirmed by a combination of TEM and EDX or by IR.

[0044] When the oxide of the element X contains an X-O-M2-O-X bond, the emitting layers EML4 and EML5 contain the compound of M2. For example, as shown in FIG. 11, when the oxide of Si element (silicon oxide) that is the additive XO4 of the quantum dot QD contains a Si-O-Ca-O-Si bond, the emitting layer EML4 contains, for example, CaCl ２and Ca(OH) ２ As shown in FIG. 12, when the oxide of Si element (silicon oxide) which is the additive XO5 of the quantum dot QD contains a Si—O—Mg—O—Si bond, the emitting layer EML5 contains, for example, MgCl ２ and Mg(OH) ２ Although not shown, when the oxide of Si element (silicon oxide) that is an additive of the quantum dot QD contains a Si—O—Be—O—Si bond, the light-emitting layer contains, for example, BeCl as the Be compound. ２ and Be(OH) ２ The compound M2 contained in the emitting layers EML4 and EML5 is not limited to a chloride or hydroxide, and may be, for example, a halide or a salt of a weak acid.

[0045] It is preferable that the value of ((the number of any element belonging to alkaline earth metals) / (the number of element X))×100% in the light-emitting layer, i.e., the value of ((the number of Ca elements) / (the number of Si elements))×100% in the light-emitting layer EML4 shown in FIG. 11 and the value of ((the number of Mg elements) / (the number of Si elements))×100% in the light-emitting layer EML5 shown in FIG. 12 , are 0.1% or more and 10% or less. As described above, by setting the content of any element belonging to alkaline earth metals in the light-emitting layer relative to element X, which is contained in the oxide in a larger amount than any element belonging to alkaline earth metals and which constitutes the skeleton of the oxide together with element oxygen, within the above-mentioned predetermined range, a light-emitting device 10 having a more stable light-emitting layer can be realized.

[0046] In the oxide of X element that is the quantum dot QD adduct XO4 or XO5, the number of O-M2-O groups is preferably greater than the number of O-H groups. That is, in the oxide of Si element (silicon oxide) that is the quantum dot QD adduct XO4 shown in FIG. 11, the number of O-Ca-O groups is preferably greater than the number of O-H groups, and in the oxide of Si element (silicon oxide) that is the quantum dot QD adduct XO5 shown in FIG. 12, the number of O-Mg-O groups is preferably greater than the number of O-H groups. This configuration makes it possible to realize a light-emitting device 10 that includes emitting layers EML4 or EML5 that further suppress the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dot QDs.

[0047] 11 and 12 , the thickness of a portion of the oxide of the X element, which is the quantum dot QD adduct XO4 or XO5, provided between adjacent first and second quantum dot QDs among the multiple quantum dots QDs included in the emitting layers EML4 and EML5, is preferably 5 nm or less. The thickness of the portion of the oxide of the X element, which is the quantum dot QD adduct XO4 or XO5, may be one atomic layer or more and 5 nm or less. With this configuration, the conductivity between the quantum dots QDs in the emitting layers EML4 and EML5 is improved, thereby reducing the driving voltage of the light-emitting element 10.

[0048] Although not shown, like the emitting layers EML2 and EML3 shown in Figures 6, 7, 8, 9, and 10, the emitting layer may include a matrix having a configuration in which groups capable of bonding to or coordinating to the quantum dots QDs are omitted from the oxide of element X as the adducts XO4 and XO5 of the quantum dots QDs contained in the emitting layers EML4 and EML5 described above.

[0049] Fig. 13 is a diagram for explaining a manufacturing method of the light-emitting element 10 shown in Fig. 2. Fig. 14 is a diagram showing an example of a step of forming a light-emitting layer in the manufacturing method of the light-emitting element 10 shown in Fig. 13. Fig. 15 is a diagram showing another example of a step of forming a light-emitting layer in the manufacturing method of the light-emitting element 10 shown in Fig. 13. Fig. 16 is a diagram showing yet another example of a step of forming a light-emitting layer in the manufacturing method of the light-emitting element shown in Fig. 13.

[0050] 2 includes step S1 of forming the anode 2, step S2 of forming the hole functional layer 3, step S3 of forming the emitting layer EML, step S4 of forming the electronic functional layer 4, and step S5 of forming the cathode 5. The light-emitting element 10 has a forward stack structure in which the cathode 5 is disposed as an upper layer than the anode 2, and therefore steps S1 to S5 can be performed in this order. On the other hand, to manufacture a light-emitting element having an inverted stack structure in which the anode 2 is disposed as an upper layer than the cathode 5, steps S1 to S5 can be performed in the reverse order.

[0051] 13, the manufacturing method of the light-emitting element 10 shown in FIG. 2 includes a step S3 of forming an emission layer EML including a plurality of quantum dots QD and an oxide of an element X. In the step S3 of forming the emission layer EML, the oxide is formed to partially include an X-O-M1 bond (where O is an oxygen element, M1 is any element belonging to alkali metals, and X is contained in the oxide in a greater amount than M1 and is an element that constitutes the skeleton of the oxide together with the oxygen element) or an X-O-M2-O-X bond (where O is an oxygen element, M2 is any element belonging to alkaline earth metals, and X is contained in the oxide in a greater amount than M2 and is an element that constitutes the skeleton of the oxide together with the oxygen element). In this embodiment, the case where the element X is silicon will be described as an example, but the present invention is not limited thereto.

[0052] 14, the step S3 of forming the light-emitting layer EML includes a step S3a of forming a quantum dot layer containing a plurality of quantum dots QD and an oxide of the element X, and a step S3b of treating the quantum dot layer. In the step S3b of treating the quantum dot layer, a first solution containing the compound M1 or the compound M2 and a first solvent may be brought into contact with the quantum dot layer. Examples of the compound M1 include NaCl, NaOH, KCl, KOH, LiCl, and LiOH. Examples of the compound M2 include CaCl. ２ , Ca(OH) ２ , MgCl ２ , Mg(OH) ２ , BeCl ２, Be(OH) ２ As the first solvent, for example, a solvent capable of dissolving the compound M1 or the compound M2 can be suitably used.

[0053] 15 , the step S13 of forming the emitting layer EML may include a step S13a of forming a first quantum dot layer including a plurality of first quantum dots and a first oxide that is an oxide of element X; a step S13b of forming a second quantum dot layer including a plurality of second quantum dots having an emission peak wavelength shorter than the emission peak wavelength of the first quantum dots and a second oxide that is an oxide of element X; and a step S13c of contacting the first quantum dot layer and the second quantum dot layer with a first solution that includes the compound M1 or the compound M2 and a first solvent. By contacting the first solution with the first quantum dot layer and the second quantum dot layer with the first solution, O—H groups contained in the emitting layer can be suppressed. The order of the steps S13a of forming the first quantum dot layer and S13b of forming the second quantum dot layer is not particularly limited, as long as they are performed before the step S13c of contacting the first solution with the first quantum dot layer and the second quantum dot layer.

[0054] 16 , the forming step S23 of the emitting layer EML may include the steps of: forming a first quantum dot layer including a plurality of first quantum dots and a first oxide that is an oxide of element X; contacting the first quantum dot layer with a first solution that includes the compound of M1 or the compound of M2 and a first solvent; forming a second quantum dot layer including a plurality of second quantum dots having an emission peak wavelength shorter than the emission peak wavelength of the first quantum dots and a second oxide that is an oxide of element X; and contacting the second quantum dot layer with a second solution that includes the compound of M1 or the compound of M2 and a second solvent. Furthermore, as the second solvent, for example, a solvent that can dissolve the compound of M1 or the compound of M2 can be suitably used. Note that one of the steps S23a to form the first quantum dot layer and S23c to form the second quantum dot layer may be performed before the other. Therefore, the steps S23c to form the second quantum dot layer, S23d to contact the second solution with the second quantum dot layer, S23a to form the first quantum dot layer, and S23b to contact the first solution with the first quantum dot layer may be performed in this order. Furthermore, the composition of the first solution used in the step S23b to contact the first solution with the first quantum dot layer and the composition of the second solution used in the step S23d to contact the second solution with the second quantum dot layer may be the same or different. Examples of solutions with different compositions include solutions containing different types of M1 compound or M2 compound, solutions containing different amounts of M1 compound or M2 compound and solvent, and solutions containing different types of solvent.

[0055] Although not shown, in the step S3 of forming the emitting layer EML, the emitting layer EML may be formed using a fourth solution containing a plurality of quantum dots QDs containing an oxide of the element X as an additive, the compound M1 or the compound M2, and a fourth solvent. In this case, the emitting layer EML can be formed in fewer steps.

[0056] FIG. 17 is a diagram showing a schematic configuration of the emitting layer EML6 that can be provided in the light emitting element 10 shown in FIG.

[0057] The emitting layer EML6 contains an oxide of the element X as an adduct XO6 of the quantum dots QD. In this embodiment, as shown in Fig. 13 , the emitting layer EML6 contains Si as the element X and an oxide of the Si element (silicon oxide) as an adduct XO6 of the quantum dots QD.

[0058] The oxide of element X partially contains the X-O-M1 bond and X-O-M2-O-X bond described above. In this embodiment, a case where M1 is sodium, M2 is magnesium, and the oxide of Si element (silicon oxide) partially contains Si-O-Na bonds and Si-O-Mg-O-Si bonds will be described as an example, but the present invention is not limited to this. With this configuration, a light-emitting element 10 can be realized that includes an emitting layer EML6 that suppresses water generation due to dehydration condensation between hydroxyl groups (-OH) in the oxide that protects the quantum dots QDs.

[0059] When the oxide of element X contains the X-O-M1 bond and X-O-M2-O-X bond described above, the emitting layer EML6 contains the M1 compound and the M2 compound. For example, as shown in Figure 17, when the oxide of element Si (silicon oxide) that is the quantum dot QD adduct XO6 contains an X-O-Na bond and an Si-O-Mg-O-Si bond, the emitting layer EML6 contains a Na compound and a Mg compound. As described above, when the emitting layer EML6 contains an alkali metal chloride or an alkaline earth metal chloride, the emitting layer EML6 contains chlorine.

[0060] It is preferable that the value of ((the number of any element belonging to the alkali metals + the number of any element belonging to the alkaline earth metals) / (the number of elements X))×100% in the light-emitting layer, i.e., the value of ((the number of Na elements + the number of Mg elements) / (the number of Si elements))×100% in the light-emitting layer EML6 shown in FIG. 17 be 0.1% or more and 10% or less. As described above, by setting the content of any element belonging to the alkali metals and any element belonging to the alkaline earth metals in the light-emitting layer relative to element X, which is contained in the oxide in a larger amount than any element belonging to the alkali metals and any element belonging to the alkaline earth metals and which constitutes the skeleton of the oxide together with element oxygen, within the above-mentioned predetermined range, it is possible to realize a light-emitting element 10 having a light-emitting layer with higher stability.

[0061] In the oxide of element X that is the adduct XO6 of quantum dots QD, the total number of OM1 groups and OM2O groups is preferably greater than the number of O-H groups. That is, in the oxide of element Si (silicon oxide) that is the adduct XO6 of quantum dots QD shown in FIG. 17, the total number of O-Na groups and O-Mg-O groups is preferably greater than the number of O-H groups. This configuration makes it possible to realize a light-emitting device 10 that includes an emitting layer EML6 that further suppresses water generation due to dehydration condensation between hydroxyl groups (-OH) in the oxide that protects the quantum dots QD.

[0062] 17 , the thickness of a portion of the oxide of the X element, which is the quantum dot QD adduct XO6, provided between adjacent first and second quantum dots QDs included in the emitting layer EML6 is preferably 5 nm or less. The thickness of the portion of the oxide of the X element, which is the quantum dot QD adduct XO6, may be one atomic layer or more and 5 nm or less. With this configuration, the content of the oxide of the X element, which is the quantum dot QD adduct XO6 and does not contribute to light emission, can be reduced in the emitting layer EML6.

[0063] Although not shown, like the emitting layers EML2 and EML3 shown in Figures 6, 7, 8, 9, and 10, the emitting layer may include a matrix having a configuration in which groups capable of bonding to or coordinating to the quantum dots QDs are omitted from the oxide of element X as the adduct XO6 of the quantum dots QDs contained in the emitting layer EML6 described above.

[0064] As shown in FIG. 1 , the display device 1 includes a first light-emitting element including a first light-emitting layer that emits light of a first emission color and a second light-emitting element including a second light-emitting layer that emits light of a second emission color having an emission peak wavelength shorter than the emission peak wavelength of the first emission color. For example, when the first light-emitting element is a red light-emitting element, the second light-emitting element is a green or blue light-emitting element, and when the first light-emitting element is a green light-emitting element, the second light-emitting element is a blue light-emitting element. At least one of the first light-emitting layer and the second light-emitting layer preferably includes M1 and M2, and the ratio of the number of M1s to the number of M2s per unit volume of the first light-emitting layer is preferably different from the ratio of the number of M1s to the number of M2s per unit volume of the second light-emitting layer. This configuration allows carrier transportability and injection properties to be adjusted according to the emission color, thereby achieving a display device 1 with high luminous efficiency. Furthermore, the number of M2s per unit volume of the second light-emitting layer is preferably greater than the number of M2s per unit volume of the first light-emitting layer. According to this configuration, electron injection can be improved in the second light-emitting element, which is less susceptible to electron injection compared to the first light-emitting element, and a display device 1 with high luminous efficiency can be realized.

[0065] Fig. 18 is a diagram showing an example of a step of forming the emitting layer EML6 shown in Fig. 17. Fig. 19 is a diagram showing another example of the step of forming the emitting layer EML6 shown in Fig. 17. Fig. 20 is a diagram showing yet another example of the step of forming the emitting layer EML6 shown in Fig. 17.

[0066] 18, the step of forming the emitting layer EML6 shown in FIG. 17 may include a step S33a of forming a quantum dot layer containing a plurality of quantum dots QD and an oxide of the element X, a step S33b of contacting the quantum dot layer with a second solution containing the compound of M2 and a second solvent, and a step (S33c) of contacting the quantum dot layer with a third solution containing the compound of M1 and a third solvent, which is performed after the step S33b of contacting the quantum dot layer with the second solution.

[0067] 19 , the step of forming the emitting layer EML6 shown in FIG. 17 may include a step S43a of forming a first quantum dot layer including a plurality of first quantum dots and a first oxide that is an oxide of the element X, and a step S43b of forming a second quantum dot layer including a plurality of second quantum dots having an emission peak wavelength shorter than the emission peak wavelength of the first quantum dots and a second oxide that is an oxide of the element X, and may also include a step S43c of contacting the first quantum dot layer and the second quantum dot layer with a second solution that includes the compound of M2 and a second solvent, and a step S43d of contacting the first quantum dot layer and the second quantum dot layer with a third solution that includes the compound of M1 and a third solvent.

[0068] 20 , the step of forming the emitting layer EML6 shown in FIG. 17 may include the steps of: forming a first quantum dot layer including a plurality of first quantum dots and a first oxide that is an oxide of the element X; contacting the first quantum dot layer with a second solution that includes the compound of M2 and a second solvent; contacting the first quantum dot layer with a third solution that includes the compound of M1 and a third solvent; forming a second quantum dot layer including a plurality of second quantum dots having an emission peak wavelength that is shorter than the emission peak wavelength of the first quantum dots and a second oxide that is an oxide of the element X; contacting the second quantum dot layer with a fourth solution that includes the compound of M2 and a fourth solvent; and contacting the second quantum dot layer with a fifth solution that includes the compound of M1 and a fifth solvent. Although the case where the above-described steps S53a to S53c are performed before the above-described steps S53d to S53f has been described as an example, the present invention is not limited to this, and the above-described steps S53d to S53f may be performed before the above-described steps S53a to S53c. Furthermore, the composition of the second solution used in the above-described step S53b and the composition of the fourth solution used in the above-described step S53e may be the same or different, and the composition of the third solution used in the above-described step S53c and the composition of the fifth solution used in the above-described step S53f may be the same or different.

[0069] As shown in Figures 18, 19, and 20, it is preferable to first treat the quantum dot layer with the M2 compound and then treat it with the M1 compound. When the quantum dot QD adduct XO6 formed in this manner or a matrix having the same composition as the quantum dot QD adduct XO6 is used, a higher cross-linking effect can be obtained. This is not a limitation, and the quantum dot layer may first be treated with the M1 compound and then treated with the M2 compound.

[0070] 17, the emitting layer EML6 may be formed using a solution containing a plurality of quantum dots QDs containing an oxide of the element X as an additive, the compound of M1, the compound of M2, and a solvent. In this case, the emitting layer EML6 can be formed in fewer steps.

[0071] Fig. 21 is a diagram showing a schematic configuration of the emitting layer EML7 that can be provided in the light-emitting element 10 shown in Fig. 2. Fig. 22 is a diagram showing the R １ group, R ２ Groups and R ３ 1A and 1B are diagrams showing preferred examples of each group.

[0072] The emitting layer EML7 contains an oxide of element X as the quantum dot QD adduct XO7. In this embodiment, as shown in FIG. 21 , the emitting layer EML7 contains Si as the element X and an oxide of Si element (silicon oxide) as the quantum dot QD adduct XO7. The oxide of element X partially contains at least one of the X-O-M1 bond and the X-O-M2-O-X bond described above, and in a part of the terminal portion of the chemical structure of the oxide of element X, the atom of element X is bonded to one hydrocarbon group and one oxygen atom, the number of which is the valence of the atom of element X, and the hydrocarbon group is at the terminal of the chemical structure of the oxide. In this embodiment, as shown in FIG. 21 , M1 is sodium, and the oxide of Si element (silicon oxide) partially contains a Si-O-Na bond, and the Si atom is bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３ Although the present invention is not limited to this example, the light-emitting element 10 includes an emitting layer EML7 that is bonded to one hydroxyl group (—OH) and one oxygen atom. This configuration makes it possible to realize a light-emitting element 10 including an emitting layer EML7 that suppresses water generation due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots QD.

[0073] As shown in FIG. 21, in an oxide of Si element (silicon oxide), Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３To incorporate a moiety bonded to one oxygen atom, for example, a hydrocarbon group R １ group, R ２ Groups and R ３ trimethylsilanol shown below (chemical formula 1), in which all groups are methyl groups; １ group, R ２ Groups and R ３ Methylethylpropylsilanol shown in the following (chemical formula 2), in which the groups are a methyl group, an ethyl group, and a propyl group, and hexamethyldisilazane shown in the following (chemical formula 3), which is an example of a hexaalkyldisilazane, can be suitably used. When trimethylsilanol shown in the following (chemical formula 1), methylethylpropylsilanol shown in the following (chemical formula 2), and hexamethyldisilazane shown in the following (chemical formula 3) are used, the Si atom is bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３ When hexamethyldisilazane shown in the following (chemical formula 3) is used, the NH moiety of hexamethyldisilazane is cleaved to form NH ３ While releasing the silanol group of the oxide of Si element (silicon oxide), the Si atom bonds with the silanol group of the oxide of Si element (silicon oxide), and the Si atom is bonded with three hydrocarbon groups (R １ group, R ２ Groups and R ３ group) and one oxygen atom.

[0074] As shown in FIG. 22, R contained in the emitting layer EML7 shown in FIG. １ group, R ２ Groups and R ３ Each of the groups is preferably a group with a shorter alkyl length, such as trimethylsilanol shown above (Chemical Formula 1). １ group, R ２ Groups and R ３ Most preferably, each of the groups is a methyl group. １ group, R ２ Groups and R ３The groups may be the same or different, but when they are different, they may be different from each other, such as methylethylpropylsilanol shown in the above (chemical formula 2). １ group, R ２ Groups and R ３ It is preferred that each of the groups is a short chain. １ group, R ２ Groups and R ３ Each group may contain a cycloalkane, as shown in Figure 22, which can improve stability due to the absence of unsaturated bonds. １ group, R ２ Groups and R ３ Each of the groups may contain a benzene ring, as shown in Figure 22, and may be, for example, phenanthrene, anthracene, triphenylene, naphthacene, and the like, which contain three or more benzene rings. １ group, R ２ Groups and R ３ When each of the groups contains a benzene ring, the electrical conductivity is improved, and an increase in the driving voltage of the light-emitting element 10 can be suppressed.

[0075] In the process of forming the emitting layers EML and EML1 to EML7 described above, a quantum dot QD dispersion containing quantum dots QDs containing an oxide of element X as an additive and a dispersion medium can be used. The oxide of element X contained in the quantum dot QD dispersion contains at least one of an X-O-M1 bond (where O is oxygen, M1 is any element belonging to the alkali metals, and X is the element X, which is contained in the oxide in a greater amount than M1 and forms the oxide framework together with the oxygen element) and an X-O-M2-O-X bond (where O is oxygen, M2 is any element belonging to the alkaline earth metals, and X is the element X, which is contained in the oxide in a greater amount than M2 and forms the oxide framework together with the oxygen element). This quantum dot QD dispersion can suppress the aggregation of quantum dots protected by the oxide, resulting in a more stable quantum dot dispersion. The oxide of element X contained in the quantum dot QD dispersion is preferably an insulator. When the oxide of element X contained in the quantum dot QD dispersion contains the X-O-M1 bond, the quantum dot QD dispersion contains the compound M1; when the oxide of element X contained in the quantum dot QD dispersion contains the X-O-M2-O-X bond, the quantum dot QD dispersion contains the compound M2; when the oxide of element X contained in the quantum dot QD dispersion contains the X-O-M1 bond and the X-O-M2-O-X bond, the quantum dot QD dispersion contains the compound M1 and the compound M2, and the quantum dot QD dispersion preferably contains chlorine. When the quantum dot QD dispersion contains chlorine, a quantum dot QD dispersion in which aggregation of the quantum dot QDs is further suppressed can be achieved. Furthermore, the element X in the oxide of element X in the quantum dot QD dispersion is preferably silicon. In this case, a quantum dot QD dispersion with a higher protection effect for the quantum dot QDs and better stability can be achieved. The oxide of element X contained in the quantum dot dispersion preferably contains an X-O-M1 bond and an X-O-M2-O-X bond, and M1 is preferably sodium and M2 is preferably magnesium.The value of ((the number of M1+the number of M2) / (the number of element X))×100% in the quantum dot dispersion is preferably 0.1% or more and 10% or less. Furthermore, in the oxide of element X contained in the quantum dot QD dispersion, it is preferable that the total number of OM1 groups and OM2O groups is larger than the number of O—H groups. The oxide of element X contained in the quantum dot QD dispersion is X—(CH. ２ )n-L bonds (X is the element X, C is a carbon element, H is a hydrogen element, n is a natural number, and L is a group capable of bonding to or coordinating with the quantum dots) are preferably included in part of the terminal portion of the chemical structure of the oxide of element X contained in the quantum dot QD dispersion. Furthermore, in part of the terminal portion of the chemical structure of the oxide of element X, the atom of element X is bonded to one hydrocarbon group and one oxygen atom, the number of which is equal to the valence of the atom of element X, and the hydrocarbon group may be at the terminal of the chemical structure of the oxide.

[0076] [Additional Notes] The present disclosure is not limited to the above-described embodiments, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present disclosure. Furthermore, new technical features can be formed by combining the technical means disclosed in each embodiment.

[0077] The present disclosure can be used in a quantum dot dispersion, a light-emitting device, a display device, and a method for manufacturing a light-emitting device.

[0078] 1 Display device 2 Anode 3 Hole functional layer 4 Electron functional layer 5 Cathode XO, XO1, XO4 to XO7 Additive XO2 Matrix QD, QDA, QDB Quantum dot EML, EML1 to EML7 Emitting layer RSP Red subpixel GSP Green subpixel BSP Blue subpixel PIX Pixel DA Display area NDA Frame area

Claims

1. A quantum dot dispersion comprising quantum dots containing an oxide of element X as an additive and a dispersion medium, wherein the oxide partially contains at least one of an X-O-M1 bond (where O is oxygen, M1 is any element belonging to the alkali metals, and X is the element X that is contained in the oxide in a greater amount than M1 and that constitutes the oxide's skeleton together with the oxygen element) and an X-O-M2-O-X bond (where O is oxygen, M2 is any element belonging to the alkaline earth metals, and X is the element X that is contained in the oxide in a greater amount than M2 and that constitutes the oxide's skeleton together with the oxygen element).

2. The quantum dot dispersion according to claim 1, wherein the oxide is an insulator.

3. The quantum dot dispersion according to claim 1 or 2, wherein the oxide contains the compound M1 when it contains the X-O-M1 bond, the oxide contains the compound M2 when it contains the X-O-M2-O-X bond, and the quantum dot dispersion according to claim 1 or 2, wherein the oxide contains the compound M1 and the compound M2 when it contains the X-O-M1 bond and the X-O-M2-O-X bond.

4. The quantum dot dispersion according to any one of claims 1 to 3, which contains chlorine.

5. A quantum dot dispersion according to any one of claims 1 to 4, wherein the element X is silicon.

6. A quantum dot dispersion liquid according to any one of claims 1 to 5, wherein M1 is sodium and M2 is magnesium.

7. A quantum dot dispersion liquid according to any one of claims 1 to 6, wherein the value of ((the number of M1s + the number of M2s) / (the number of elements X)) x 100% is 0.1% or more and 10% or less.

8. A quantum dot dispersion liquid according to any one of claims 1 to 7, wherein in the oxide, the total number of O-M1 groups and O-M2-O groups is greater than the number of O-H groups.

9. The oxide is X—(CH ２ 9. The quantum dot dispersion liquid according to claim 1, wherein the quantum dots are partly composed of n-L bonds (wherein X is the element X, C is a carbon element, H is a hydrogen element, n is a natural number, and L is a group capable of bonding to or coordinating with the quantum dots).

10. A quantum dot dispersion liquid according to any one of claims 1 to 9, wherein, in a part of a terminal portion of the chemical structure of the oxide, the atom of element X is bonded to one hydrocarbon group and one oxygen atom whose valence is minus one of the valences of the atom of element X, and the hydrocarbon group is at the terminal of the chemical structure of the oxide.

11. A light-emitting device comprising: an anode; a cathode; and a light-emitting layer provided between the anode and the cathode and including quantum dots, wherein the light-emitting layer contains an oxide of element X as an additive to the quantum dots or as a matrix filling at least a portion of the gaps between the quantum dots, and the oxide contains at least one of an X-O-M1 bond (where O is an oxygen element, M1 is any element belonging to alkali metals, and X is the element X that is contained in the oxide in a greater amount than M1 and that constitutes the skeleton of the oxide together with the oxygen element) and an X-O-M2-O-X bond (where O is an oxygen element, M2 is any element belonging to alkaline earth metals, and X is the element X that is contained in the oxide in a greater amount than M2 and that constitutes the skeleton of the oxide together with the oxygen element).

12. The light-emitting element according to claim 11, wherein the oxide is an insulator.

13. The light-emitting device according to claim 11 or 12, wherein when the oxide contains the X-O-M1 bond, the light-emitting layer contains the compound of M1; when the oxide contains the X-O-M2-O-X bond, the light-emitting layer contains the compound of M2; and when the oxide contains the X-O-M1 bond and the X-O-M2-O-X bond, the light-emitting layer contains the compound of M1 and the compound of M2.

14. The light-emitting element according to any one of claims 11 to 13, wherein the light-emitting layer contains chlorine.

15. The light-emitting device according to any one of claims 11 to 14, wherein the element X is silicon.

16. The light-emitting element according to any one of claims 11 to 15, wherein M1 is sodium, and M2 is magnesium.

17. The light-emitting element according to any one of claims 11 to 16, wherein the value of ((the number of M1's + the number of M2's) / (the number of elements X)) x 100% in the light-emitting layer is 0.1% or more and 10% or less.

18. A light-emitting device according to any one of claims 11 to 17, wherein in the oxide, the total number of O-M1 groups and O-M2-O groups is greater than the number of O-H groups.

19. The oxide is X—(CH ２ 19. The light-emitting device according to claim 11, wherein the light-emitting element partially contains an n-L bond (wherein X is the element X, C is a carbon element, H is a hydrogen element, n is a natural number, and L is a group capable of bonding to or coordinating with the quantum dot).

20. The light-emitting element according to any one of claims 11 to 19, wherein in a part of a terminal portion of the chemical structure of the oxide, the atom of element X is bonded to one hydrocarbon group and one oxygen atom whose valence is minus one of the atom of element X, and the hydrocarbon group is at the terminal of the chemical structure of the oxide.

21. A light-emitting element according to any one of claims 11 to 20, wherein the thickness of a portion of the oxide provided between adjacent first and second quantum dots among the plurality of quantum dots is 5 nm or less.

22. A display device comprising a plurality of light-emitting elements according to any one of claims 11 to 21, wherein the plurality of light-emitting elements comprise a first light-emitting element including a first light-emitting layer that emits light in a first light-emitting color as the light-emitting layer, and a second light-emitting element including a second light-emitting layer that emits light in a second light-emitting color having an emission peak wavelength on the shorter wavelength side than the emission peak wavelength of the first light-emitting color, at least one of the first light-emitting layer and the second light-emitting layer comprising M1 and M2, wherein the ratio of the number of M1 to the number of M2 per unit volume of the first light-emitting layer is different from the ratio of the number of M1 to the number of M2 per unit volume of the second light-emitting layer.

23. The display device according to claim 22, wherein the number of M2s per unit volume of the second light-emitting layer is greater than the number of M2s per unit volume of the first light-emitting layer.

24. A method for manufacturing a light-emitting element, comprising the step of forming a light-emitting layer containing a plurality of quantum dots and an oxide of element X, wherein the step of forming the light-emitting layer forms the oxide having at least one of an X-O-M1 bond (where O is oxygen, M1 is any element belonging to alkali metals, and X is the element X that is contained in the oxide in a greater amount than M1 and that constitutes the skeleton of the oxide together with the oxygen element) and an X-O-M2-O-X bond (where O is oxygen, M2 is any element belonging to alkaline earth metals, and X is the element X that is contained in the oxide in a greater amount than M2 and that constitutes the skeleton of the oxide together with the oxygen element).

25. The method for manufacturing a light-emitting element according to claim 24, wherein the step of forming the light-emitting layer includes a step of forming a quantum dot layer containing the plurality of quantum dots and the oxide, and a step of treating the quantum dot layer, wherein the step of treating the quantum dot layer includes contacting the quantum dot layer with a first solution containing at least one of the compound M1 and the compound M2 and a first solvent.

26. The method for manufacturing a light-emitting element according to claim 24, wherein the step of forming the light-emitting layer includes a step of forming a quantum dot layer containing the plurality of quantum dots and the oxide, and a step of treating the quantum dot layer, and the step of treating the quantum dot layer includes a first step of bringing the quantum dot layer into contact with a second solution containing the compound of M2 and a second solvent, and a second step, which is performed after the first step, of bringing the quantum dot layer into contact with a third solution containing the compound of M1 and a third solvent.

27. A method for manufacturing a light-emitting element as described in claim 25, wherein the step of forming the quantum dot layer includes a step of forming a first quantum dot layer containing a plurality of first quantum dots and a first oxide that is the oxide, and a step of forming a second quantum dot layer containing a plurality of second quantum dots that have an emission peak wavelength shorter than the emission peak wavelength of the first quantum dots and a second oxide that is the oxide, and wherein the step of treating the quantum dot layer includes bringing the first solution into contact with the first quantum dot layer and the second quantum dot layer.

28. A method for manufacturing a light-emitting element as described in claim 26, wherein the step of forming the quantum dot layer includes the steps of forming a first quantum dot layer containing a plurality of first quantum dots and a first oxide that is the oxide, and forming a second quantum dot layer containing a plurality of second quantum dots that have an emission peak wavelength on the shorter wavelength side than the emission peak wavelength of the first quantum dots and a second oxide that is the oxide, wherein in the first step, the second solution is brought into contact with the first quantum dot layer and the second quantum dot layer, and in the second step, the third solution is brought into contact with the first quantum dot layer and the second quantum dot layer.

29. A method for manufacturing a light-emitting element according to claim 25 or 26, wherein the step of forming the light-emitting layer includes the steps of: forming a first quantum dot layer containing a plurality of first quantum dots and a first oxide that is the oxide; treating the first quantum dot layer; forming a second quantum dot layer containing a plurality of second quantum dots that have an emission peak wavelength shorter than the emission peak wavelength of the first quantum dots and a second oxide that is the oxide; and treating the second quantum dot layer; and wherein one of the steps of forming the first quantum dot layer and forming the second quantum dot layer is performed before the other.

30. The method for manufacturing a light-emitting element according to claim 29, wherein the composition of the solution used in the step of treating the first quantum dot layer is different from the composition of the solution used in the step of treating the second quantum dot layer.

31. A method for manufacturing a light-emitting element as described in claim 24, wherein in the step of forming the light-emitting layer, the light-emitting layer is formed using a fourth solution containing a plurality of quantum dots containing the oxide as an additive, at least one of the M1 compound and the M2 compound, and a fourth solvent.

32. A method for manufacturing a light-emitting device according to any one of claims 24 to 31, wherein the element X is silicon.

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