Quantum dot dispersion liquid, light-emitting element, and light-emitting element production method

Abstract

A light-emitting element (10) comprises: an anode (2); a cathode (5); and a light-emitting layer (EML) that is provided between the anode (2) and the cathode (5) and that includes quantum dots (QD). The light-emitting layer (EML) contains an oxide of elemental Si as an adduct (XO) of the quantum dots (QD), and an Si atom is bonded to one oxygen atom and three hydrocarbon groups (R1, R2, and R3) of the Si atom at a part of terminal portions of the chemical structure of the oxide. The hydrocarbon groups (R1, R2, and R3) are each a terminal of the chemical structure of the oxide. The elemental Si is contained in the oxide in a greater amount than that of elemental carbon, and, together with elemental oxygen, forms the backbone of the oxide.

Description

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

[0001] The present disclosure relates to a dispersion of quantum dots, a light-emitting 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 aggregation of quantum dots protected by an oxide is suppressed, and a light-emitting device that includes a light-emitting layer that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots, and a method for manufacturing the light-emitting device.

[0007] In order to solve the above-mentioned problems, the quantum dot dispersion liquid of the present disclosure comprises quantum dots containing an oxide of element X as an adduct, and a dispersion medium, wherein in a part of a terminal portion of the chemical structure of the oxide, an atom of the element X is bonded to a hydrocarbon group and one oxygen atom whose valence is minus one of the atoms of the element X, the hydrocarbon group being the terminal of the chemical structure of the oxide, and the element X being contained in the oxide in a larger amount than the carbon element, and being an element that constitutes the skeleton of the oxide together with the oxygen element.

[0008] In order to solve the above-mentioned problems, 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 element X as an adduct of the quantum dots or a matrix filling at least a portion of the gaps between the quantum dots, wherein an atom of element X is bonded to a hydrocarbon group and one oxygen atom whose valence is minus one of the atom of element X in a part of a terminal portion of a chemical structure of the oxide, and the element X is contained in the oxide in a larger amount than carbon element, and is an element that constitutes the skeleton of the oxide together with oxygen element.

[0009] 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, wherein in the step of forming the light-emitting layer, the oxide is formed which contains, as a part thereof, one hydrocarbon group whose valence is minus one of the atoms of element X bonded to the atom of element X and one oxygen atom, and the element X is contained in the oxide in a larger amount than carbon element, and is an element which constitutes the skeleton of the oxide together with oxygen element.

[0010] 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 aggregation of quantum dots protected by an oxide is suppressed, and a light-emitting device including a light-emitting layer that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots, and a method for manufacturing the light-emitting device.

[0011] 2 is a plan view showing a schematic configuration of a display device of Embodiment 1. FIG. 3 is a cross-sectional view showing a schematic configuration of a light-emitting element provided in the display device of Embodiment 1. FIG. 4 is a diagram showing a schematic configuration of a light-emitting layer provided in the light-emitting element shown in FIG. 2. R contained in the light-emitting layer shown in FIG. １ group, R ２ Groups and R ３ 2 is a diagram showing a preferred example of each group. FIG. 3 is a cross-sectional view showing a schematic configuration of the light-emitting layer shown in FIG. 3. FIG. 4 is a diagram showing a schematic configuration of another light-emitting layer that can be provided in the light-emitting device shown in FIG. 2. FIG. 5 is a diagram showing a schematic configuration of another light-emitting layer that can be provided in the light-emitting device shown in FIG. 2. FIG. 6 is a cross-sectional view showing a schematic configuration of one embodiment of the light-emitting layer shown in FIGS. 6 and 7. FIG. 7 is a cross-sectional view showing a schematic configuration of another embodiment of the light-emitting layer shown in FIGS. 6 and 7. FIG. 8 is a cross-sectional view showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting device shown in FIG. 2. FIG. 9 is a diagram showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting device shown in FIG. 2. FIG. 10 is a diagram showing a schematic configuration of yet another light-emitting layer that can be provided in the light-emitting device shown in FIG. 10. FIG. 11 is a diagram for explaining a method for manufacturing the light-emitting device shown in FIG. 2. FIG. 16 is a diagram showing an example of a step of forming a light-emitting layer in a method for manufacturing the light-emitting device shown in FIG. 16. FIG. 17 is a diagram showing another example of a step of forming a light-emitting layer in a method for manufacturing the light-emitting device shown in FIG. 16. FIG. 18 is a diagram showing yet another example of a step of forming a light-emitting layer in a method for manufacturing the light-emitting device shown in FIG. 16. FIG. 10 is a diagram showing a schematic configuration of a light-emitting layer provided in a light-emitting element that is a comparative example.

[0012] The following describes embodiments of the present disclosure with reference to Figures 1 to 20. 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 their description may be omitted.

[0013] First Embodiment FIG. 1 is a plan view showing a schematic configuration of a display device 1 according to a first embodiment.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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 shows the R １ group, R ２ Groups and R ３ 20 is a diagram showing a schematic configuration of an emitting layer EML' provided in a light-emitting element as a comparative example.

[0023] As shown in Figure 20, 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).

[0024] The emitting layer EML shown in Figure 3 contains an oxide of element X as the quantum dot QD additive XO. In this embodiment, the emitting layer EML contains Si as the element X and an oxide of Si (silicon oxide) as the quantum dot QD additive XO. However, the present invention is not limited to this. The emitting layer EML may contain, as the quantum dot QD additive XO, an oxide such as an oxide of Al (aluminum oxide), an oxide of Ti (titanium oxide), or an oxide of Zr (zirconium oxide). When an oxide of Si (silicon oxide) is contained as the quantum dot QD additive XO, 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.

[0025] In a part of the terminal portion of the chemical structure of the oxide of element X as the adduct XO of the quantum dot QD, the atom of element X is connected to the valence of the atom of element X minus one hydrocarbon group (R １ group, R ２ Groups and R ３ group) and one oxygen atom, and １ group, R ２ Groups and R ３The element X is contained in the oxide in a larger amount than the carbon element and constitutes the skeleton of the oxide together with the oxygen element. In this embodiment, as shown in FIG. 3, in a part of the terminal portion of the chemical structure of the oxide of the Si element (silicon oxide) as the adduct XO of the quantum dot QD, the atom of the Si element is bound to three hydrocarbon groups (R １ group, R ２ Groups and R ３ With this configuration, it is possible to realize a light-emitting element 10 including an emitting layer EML that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots QD.

[0026] As shown in FIG. 3, in an oxide of Si element (silicon oxide), Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３ To incorporate a moiety bonded to 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 ３While 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.

[0027] As shown in FIG. 4, R contained in the emitting layer EML 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 ３ The 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 The number of carbon atoms contained in the hydrocarbon group (R group) is preferably 5 or less. A hydrocarbon group having 5 or less carbon atoms allows the QDs to be closer to each other, thereby realizing a light-emitting element 10 with a low driving voltage. １ group, R ２ Groups and R ３ The R group is preferably a linear alkyl group. A linear alkyl group exhibits particularly low reactivity, and therefore is highly stable and can suppress dehydration condensation between hydroxyl groups (—OH). This makes it possible to realize a light-emitting element 10 having an emitting layer EML that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots QD. １ group, R ２ Groups and R ３Each group may contain a cycloalkane, as shown in FIG. 4, which can improve stability due to the absence of unsaturated bonds. １ group, R ２ Groups and R ３ The R group is preferably a saturated hydrocarbon group. Since a saturated hydrocarbon group exhibits high stability, it is possible to suppress dehydration condensation between hydroxyl groups (—OH), and it is possible to realize a light-emitting device 10 including an emitting layer EML that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QD. Furthermore, １ group, R ２ Groups and R ３ Each of the groups may contain a benzene ring, as shown in FIG. 4, such as phenanthrene, anthracene, triphenylene, and naphthacene, 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.

[0028] The oxide of element X as the adduct XO of quantum dots QDs means that 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 Figure 3, the oxide of element Si as the adduct XO of quantum dots QDs means that at least a portion of the Si element is 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 QDs containing an oxide of element Si as the adduct XO shown in Figure 3 may have an organic moiety, such as an organic ligand, outside the oxide of element Si that is the adduct XO, although this organic moiety may be, for example, coordinately bonded or covalently bonded to the oxide of element Si that is the adduct XO.

[0029] The presence of a bond between the element X and a hydrocarbon group or a bond between the element X and an oxygen atom may be confirmed by, for example, time-of-flight secondary ion mass spectrometry (TOF-SIMS) or XPS. The presence of an oxide of Si may be confirmed by a combination of TEM and EDX or by IR.

[0030] The oxide of element X that is the adduct XO 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 as shown in Fig. 3 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 of the quantum dots QD an insulator, it is possible to suppress current flow in the emitting layer EML via the adduct XO 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.

[0031] 3 may contain a compound including an X—O—X bond (O is an oxygen element, and X is the element X), and the element X in the X—O—X bond is bonded to one hydrocarbon group, the number of which is equal to the valence of the atom of the element X. In the present embodiment, the emitting layer EML may contain a compound including an Si—O—Si bond, and three hydrocarbon groups are bonded to each Si element in the Si—O—Si bond.

[0032] The oxide of the X element, which is the adduct XO of the quantum dot QD, preferably contains more hydrocarbon groups than O—H groups. That is, in the oxide of the Si element (silicon oxide) which is the adduct XO of the quantum dot QD shown in FIG. 3, the hydrocarbon groups (R １ group, R ２ Groups and R ３ It is preferable that the number of hydroxyl groups (—OH) is larger than the number of O—H groups. With this configuration, it is possible to realize a light-emitting element 10 including an emitting layer EML that further suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide that protects the quantum dots QD.

[0033] In the emitting layer EML shown in FIG. 3, the oxide of element X, which is the adduct XO of the quantum dot QD contained in the emitting layer EML, is X—(CH２ )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 FIG. 3, the oxide of Si, which is an adduct XO of quantum dots QDs contained in the light-emitting layer EML, is 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] The thickness of a portion of the oxide of the X element, which is the adduct XO of the quantum dot QDs provided between adjacent first and second quantum dots QDs among the multiple quantum dots QDs included in the emission layer EML shown in Fig. 3, is preferably 5 nm or less. Note that the thickness of the portion of the oxide of the X element, which is the adduct XO of the quantum dot QDs, 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 adduct XO of the quantum dot QDs that does not contribute to light emission, can be reduced in the emission layer EML.

[0035] 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 another emitting layer EML1 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 EML1 shown in Figs. 6 and 7. Fig. 9 is a cross-sectional view showing a schematic configuration of another embodiment of the emitting layer EML1 shown in Figs. 6 and 7. Fig. 10 is a cross-sectional view showing a schematic configuration of yet another emitting layer EML2 that can be provided in the light-emitting device 10 shown in Fig. 2.

[0036] The emitting layer EML described above, based on FIG. 3 , contains an oxide of element X bound or coordinated to the quantum dots QDs as the quantum dot QD additive XO. Therefore, for example, by appropriately adjusting the amount of the quantum dot QD additive XO to cover the surface of the quantum dots QDs, 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 additive XO may be increased to fill at least a portion of the gaps between the quantum dots QDs containing the additive XO shown in FIG. 5 . Furthermore, as in the emitting layer EML2 shown in FIG. 10 , at least a portion of the gaps between the quantum dots QDs containing the additive XO may be filled with, for example, a matrix XO1, which is another additive to the quantum dots QDs and does not contain a group capable of binding or coordinating to the quantum dots QDs. The emitting layers EML1 and EML2 shown in FIGS. 6 , 7 , 8 , 9 , and 10 contain, as the quantum dot QD additive matrix XO1, an oxide of element X that is not bound or coordinated to the quantum dots QDs. In this case, the matrix XO1, which is an adduct of the quantum dots QDs, fills at least a part of the gaps between the quantum dots QDs. Note that the configuration of the oxide of element X as the matrix XO1, which is an adduct of the quantum dots QDs contained in the emitting layers EML1 and EML2, is the same as the oxide of element X as the adduct XO of the quantum dots QDs contained in the emitting layer EML described above, except that it does not contain any groups capable of bonding to or coordinating to the quantum dots QDs, and therefore a description thereof will be omitted here.

[0037] 6, the emitting layer EML1 includes a plurality of quantum dots QDA and QDB and a matrix XO1 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 XO1 that does not contain 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.

[0038] 7, in the emitting layer EML1, 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 XO1 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.

[0039] 6 and 7 , the thickness of a portion of the oxide of the X element, which is the matrix XO1 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 XO1, 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 EML1 is improved, thereby reducing the driving voltage of the light-emitting element 10.

[0040] As shown in Fig. 8, the emitting layer EML1 shown in Fig. 6 and Fig. 7 may include a matrix XO1 which 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 XO1 which 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 EML1 can also obtain the same effects as the light-emitting device 10 including the above-mentioned emitting layer EML.

[0041] Fig. 11 is a diagram showing a schematic configuration of an emitting layer EML3 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 EML4 that can be provided in the light-emitting element 10 shown in Fig. 2. Fig. 13 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. Fig. 14 is a diagram showing a schematic configuration of an emitting layer EML6 that can be provided in the light-emitting element 10 shown in Fig. 2. Fig. 15 is a diagram showing a schematic configuration of an emitting layer EML7 that can be provided in the light-emitting element 10 shown in Fig. 2.

[0042] The emitting layer EML3 shown in Fig. 11 contains an oxide of element X as the adduct XO3 of the quantum dots QD. In this embodiment, as shown in Fig. 7, the emitting layer EML3 contains Si as the element X and an oxide of Si element (silicon oxide) as the adduct XO3 of the quantum dots QD. The oxide of element X partially contains an X-O-M1 bond (O is an oxygen element, M1 is any element belonging to the alkali metals, and X is the element X), and some atoms of element X in the oxide of element X are bonded to a hydrocarbon group (R １ group, R ２ Groups and R ３ In this embodiment, as shown in FIG. 11, M1 is sodium, the oxide of Si element (silicon oxide) contains Si—O—Na bonds in part, and some Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３Although the present invention is not limited to this example, the present invention can be implemented using an example in which the quantum dot QDs are bonded to a hydroxyl group (—OH) and one oxygen atom. This configuration makes it possible to realize a light-emitting device 10 including an emitting layer EML3 that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QDs. When the oxide of the element X includes an X—O—M1 bond, the emitting layer EML3 includes the M1 compound. For example, as shown in FIG. 11 , when the oxide of Si (silicon oxide) that is the quantum dot QD adduct XO3 includes an Si—O—Na bond, the emitting layer EML3 may include, as the Na compound, NaCl or NaOH, for example. The M1 compound included in the emitting layer EML3 is not limited to a chloride or hydroxide, and may be, for example, a halide or a salt of a weak acid.

[0043] The emitting layer EML4 shown in Fig. 12 contains an oxide of element X as the adduct XO4 of the quantum dots QD. In this embodiment, as shown in Fig. 12, the emitting layer EML4 contains Si as the element X and an oxide of Si element (silicon oxide) as the adduct XO4 of the quantum dots QD. The oxide of element X partially contains an X-O-M1 bond, and some atoms of element X in the oxide of element X are bonded to a hydrocarbon group (R １ group, R ２ Groups and R ３ In this embodiment, as shown in FIG. 12, M1 is potassium, the oxide of Si element (silicon oxide) contains Si—O—K bonds in part, and some Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３Although the present invention is not limited to this example, the present invention is not limited to this example. This configuration makes it possible to realize a light-emitting device 10 including an emitting layer EML4 that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QDs. For example, as shown in FIG. 12 , when an oxide of Si (silicon oxide) that is the quantum dot QD adduct XO4 contains a Si—O—K bond, the emitting layer EML4 may contain, for example, KCl or KOH as the K compound. The compound of M1 contained in the emitting layer EML4 is not limited to a chloride or hydroxide, and may be, for example, a halide or a salt of a weak acid.

[0044] The emitting layer EML5 shown in Fig. 13 contains an oxide of element X as the adduct XO5 of the quantum dots QD. In this embodiment, as shown in Fig. 13, the emitting layer EML5 contains Si as the element X and an oxide of Si element (silicon oxide) as the adduct XO5 of the quantum dots QD. The oxide of element X partially contains an X-O-M2-O-X bond (O is an oxygen element, M2 is any element belonging to alkaline earth metals, and X is the element X), and some atoms of element X in the oxide of element X are bonded to a hydrocarbon group (R １ group, R ２ Groups and R ３ In this embodiment, as shown in FIG. 13, M2 is calcium, the oxide of Si element (silicon oxide) contains Si—O—Ca bonds in part, and some Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３Although the present invention is not limited to this example, the present invention is not limited to this example. This configuration makes it possible to realize a light-emitting device 10 including an emitting layer EML5 that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QDs. When the oxide of the element X includes an X—O—M2-O—X bond, the emitting layer EML5 includes the compound of M2. For example, as shown in FIG. 13 , when the oxide of Si (silicon oxide) that is the quantum dot QD adduct XO5 includes an Si—O—Ca bond, the emitting layer EML5 includes, as the compound of Ca, for example, CaCl ２ and Ca(OH) ２ The compound M2 contained in the emitting layer EML5 is not limited to chlorides or hydroxides, and may be, for example, a halide or a salt of a weak acid.

[0045] The emitting layer EML6 shown in Fig. 14 contains an oxide of element X as the adduct XO6 of the quantum dots QD. In this embodiment, as shown in Fig. 14, the emitting layer EML6 contains Si as the element X and an oxide of Si element (silicon oxide) as the adduct XO6 of the quantum dots QD. The oxide of element X partially contains an X-O-M2-O-X bond, and some atoms of element X in the oxide of element X are bonded to a hydrocarbon group (R １ group, R ２ Groups and R ３ In this embodiment, as shown in FIG. 14, M2 is magnesium, the oxide of Si element (silicon oxide) contains Si—O—Mg bonds in part, and some Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３Although the present invention is not limited to this example, the present invention can be implemented by taking as an example a case where the hydroxyl group (—OH) is bonded to one oxygen atom and the hydroxyl group (—OH) in the oxide protecting the quantum dots QDs. This configuration can realize a light-emitting device 10 including an emitting layer EML6 that suppresses the generation of water due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QDs. When the oxide of the element X includes an X—O—M2-O—X bond, the emitting layer EML6 includes the compound of M2. For example, as shown in FIG. 14 , when the oxide of Si element (silicon oxide) that is the adduct XO6 of the quantum dots QDs includes an Si—O—Mg bond, the emitting layer EML6 includes, as the compound of Mg, for example, MgCl ２ and Mg(OH) ２ The compound M2 contained in the emitting layer EML6 is not limited to chlorides or hydroxides, and may be, for example, a halide or a salt of a weak acid.

[0046] The emitting layer EML7 shown in Fig. 15 contains an oxide of element X as the adduct XO7 of the quantum dots QD. In this embodiment, as shown in Fig. 15, the emitting layer EML7 contains Si as the element X and an oxide of Si element (silicon oxide) as the adduct XO7 of the quantum dots QD. The oxide of element X partially contains an X-O-M1 bond and an X-O-M2-O-X bond, and some atoms of element X in the oxide of element X are bonded to a hydrocarbon group (R １ group, R ２ Groups and R ３ In this embodiment, as shown in FIG. 15, M1 is sodium, M2 is magnesium, and the oxide of Si element (silicon oxide) contains Si—O—Na bonds and Si—O—Mg bonds in part, and some Si atoms are bonded to three hydrocarbon groups (R １ group, R ２ Groups and R ３Although the present invention is not limited to this example, the present invention can be implemented by taking as an example a case where the hydroxyl group (—OH) is bonded to one oxygen atom and the hydroxyl group (—OH) in the oxide protecting the quantum dots QDs. This configuration makes it possible to realize a light-emitting device 10 including an emitting layer EML7 that suppresses water generation due to dehydration condensation between hydroxyl groups (—OH) in the oxide protecting the quantum dots QDs. When the oxide of the element X includes an X-O-M1 bond and an X-O-M2-O-X bond, the emitting layer EML7 includes the M1 compound and the M2 compound. For example, as shown in FIG. 15 , when the oxide of Si element (silicon oxide) that is the quantum dot QD adduct XO7 includes an Si—O—Na bond and an Si—O—Mg bond, the emitting layer EML7 includes a compound of Na, such as NaCl or NaOH, and a compound of Mg, such as MgCl ２ and Mg(OH) ２ The M1 compound and the M2 compound contained in the emitting layer EML7 are not limited to chlorides or hydroxides, and may be, for example, halides or salts of weak acids.

[0047] When the emitting layers EML3, EML4, and EML7 contain an alkali metal chloride, as in the case of the emitting layers EML3, EML4, and EML7 shown in Figures 11, 12, and 15, the emitting layers EML3, EML4, and EML7 contain chlorine. When the emitting layers EML5, EML6, and EML7 contain an alkaline earth metal chloride, as in the case of the emitting layers EML5, EML6, and EML7 shown in Figures 13, 14, and 15, the emitting layers EML5, EML6, and EML7 contain chlorine. Although not shown, like the emitting layers EML1 and EML2 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 XO3, XO4, XO5, XO6, and XO7 of the quantum dots QDs contained in the emitting layers EML3, EML4, EML5, EML6, and EML7 described above.

[0048] Fig. 16 is a diagram for explaining a manufacturing method of the light-emitting element 10 shown in Fig. 2. Fig. 17 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. 16. Fig. 18 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. 16. Fig. 19 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 10 shown in Fig. 16.

[0049] 16, the method for manufacturing the light-emitting element 10 shown in FIG. 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.

[0050] 16, the method for manufacturing 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 element X. In the step S3 of forming the emission layer EML, an oxide of element X is formed, the oxide of element X including, as a part thereof, one hydrocarbon group whose valence is minus one of the atoms of element X bonded to the atom of element X and one oxygen atom. Note that the element X is contained in the oxide of element X in greater amounts than carbon, and is an element that constitutes the skeleton of the oxide of element X together with oxygen. In this embodiment, a case in which the element X is silicon will be described as an example, but the present invention is not limited to this.

[0051] As shown in FIG. 17 , the step S3 of forming the emitting layer EML includes a step S3a of forming a quantum dot layer including a plurality of quantum dots QDs 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 solution containing a terminating agent may be brought into contact with the quantum dot layer. The terminating agent may include one H-O-X bond (where H is hydrogen, O is oxygen, and X is the element X), in which the atom of the element X in the H-O-X bond is bonded to a hydrocarbon group whose number is less than the valence of the atom of the element X. Examples of such a terminating agent include, but are not limited to, trimethylsilanol shown in the above (Chemical Formula 1) and methylethylpropylsilanol shown in the above (Chemical Formula 2). The terminating agent may include one Si-NH-Si bond, in which each of the two Si atoms in the Si-NH-Si bond is bonded to three alkyl groups. Such a terminating agent may include, but is not limited to, hexamethyldisilazane, which is an example of hexaalkyldisilazane shown in the above (chemical formula 3).

[0052] As shown in FIG. 18 , the step S3 of forming the emitting layer EML includes a step S13a of forming a first quantum dot layer including a plurality of first quantum dots and a first oxide which 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 which is an oxide of element X, and a step S13c of treating the quantum dot layer, and in the step S13c of treating the quantum dot layer, a solution containing the above-mentioned terminating agent may be brought into contact with the first quantum dot layer and the second quantum dot layer.

[0053] As shown in FIG. 19 , the step S3 of forming the emitting layer EML includes the steps of: a step S23a 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 S23b of treating the first quantum dot layer with a first solution containing a first terminating agent, which is a step of bringing the first quantum dot layer into contact with a first solution containing a first terminating agent; a step S23c 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 S23d of treating the second quantum dot layer with a second solution containing a second terminating agent, which is a step of bringing the second quantum dot layer into contact with a second solution containing a second terminating agent. Note that one of step S23a of forming a first quantum dot layer and step S23c of forming a second quantum dot layer may be performed before the other, so step S23c of forming a second quantum dot layer, step S23d of contacting a second solution with the second quantum dot layer, step S23a of forming a first quantum dot layer, and step S23b of contacting a first solution with the first quantum dot layer may be performed in this order. Furthermore, the composition of the first solution used in step S23b of contacting the first solution with the first quantum dot layer and the composition of the second solution used in step S23d of contacting 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 terminating agents, solutions containing different amounts of terminating agents, solutions containing different amounts of solvent, and solutions containing different types of solvent.

[0054] In the process of forming the emitting layer EML shown in Figures 3 and 5, the emitting layer EML1 shown in Figures 6, 7, 8, and 9, and the emitting layer EML2 shown in Figure 10, the quantum dot layer may be treated with a solution containing the above-mentioned terminating agent. In the process of forming the emitting layer EML3 shown in Figure 11 and the emitting layer EML4 shown in Figure 12, the quantum dot layer may be treated with a solution containing the above-mentioned terminating agent and the above-mentioned compound M1. In the process of forming the emitting layer EML5 shown in Figure 13 and the emitting layer EML6 shown in Figure 14, the quantum dot layer may be treated with a solution containing the above-mentioned terminating agent and the above-mentioned compound M2. Examples of the compound M1 that can be used 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 can be used.

[0055] Furthermore, in the step of forming the emitting layer EML7 shown in FIG. 15 , the quantum dot layer may be first treated with a solution containing the above-described terminating agent, then treated with a solution containing the above-described M2 compound, and finally treated with a solution containing the above-described M1 compound; alternatively, the quantum dot layer may be first treated with a solution containing the above-described M2 compound, then treated with a solution containing the above-described terminating agent, and finally treated with a solution containing the above-described M1 compound; alternatively, the quantum dot layer may be first treated with a solution containing the above-described M2 compound, then treated with a solution containing the above-described M1 compound, and finally treated with a solution containing the above-described terminating agent.

[0056] Although not shown in the figures, in the step S3 of forming the emitting layer EML, the emitting layer EML may be formed using a solution (third solution) containing a plurality of quantum dots QDs containing an oxide of the element X as an additive, the above-mentioned terminating agent, and a solvent; in the step S3 of forming the emitting layers EML3 and EML4, the emitting layers EML3 and EML4 may be formed using a solution containing a plurality of quantum dots QDs containing an oxide of the element X as an additive, the above-mentioned terminating agent, the above-mentioned compound of M1, and a solvent; in the step S3 of forming the emitting layers EML5 and EML6, the emitting layers EML5 and 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 above-mentioned terminating agent, the above-mentioned compound of M2, and a solvent; and in the step S3 of forming the emitting layer EML7, the emitting layer EML7 may be formed using a solution containing a plurality of quantum dots QDs containing an oxide of the element X as an additive, the above-mentioned terminating agent, the above-mentioned compound of M1, the above-mentioned compound of M2, and a solvent.

[0057] 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. In a portion of the terminal portion of the chemical structure of the oxide of element X contained in the quantum dot dispersion, the atom of element X is bonded to a hydrocarbon group and one oxygen atom whose valence is minus one of the atoms of element X, the hydrocarbon group being the terminal of the chemical structure of the oxide, and the element X is contained in the oxide of element X in greater amounts than carbon and constitutes the skeleton of the oxide of element X together with oxygen. This quantum dot QD dispersion can achieve a more stable quantum dot dispersion in which aggregation of quantum dots protected by the oxide is suppressed. The oxide of element X contained in the quantum dot QD dispersion is preferably an insulator. The oxide of element X contained in the quantum dot QD dispersion may include a compound containing an X-O-X bond (O is oxygen and X is the element X), and the atom of element X in the X-O-X bond is bonded to one hydrocarbon group, the number of which is the valence of the atom of element X minus one. 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 having a higher protective effect on the quantum dot QDs and better stability can be achieved. The hydrocarbon group is preferably a saturated hydrocarbon group or a linear alkyl group. The number of carbon atoms contained in the hydrocarbon group is preferably 5 or less. The oxide of element X contained in the quantum dot QD dispersion preferably contains more hydrocarbon groups than O-H groups. These configurations suppress aggregation of quantum dots QDs and achieve a quantum dot QD dispersion with better dispersibility. The oxide of element X contained in the quantum dot QD dispersion is preferably an 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) in part. Furthermore, the oxide of element X contained in the quantum dot QD dispersion may partially contain at least one of an X-O-M1 bond (O is an oxygen element, M1 is any element belonging to the alkali metals, and X is the element X) and an X-O-M2-O-X bond (O is an oxygen element, M2 is any element belonging to the alkaline earth metals, and X is the element X).

[0058] [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.

[0059] 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.

[0060] 1 Display device 2 Anode 3 Hole functional layer 4 Electron functional layer 5 Cathode XO, XO3 to XO7 Additive XO1 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 adduct and a dispersion medium, wherein, in a part of a terminal portion of the chemical structure of the oxide, an atom of the element X is bonded to a hydrocarbon group and one oxygen atom whose valence is minus one of the atoms of the element X, the hydrocarbon group being at the terminal of the chemical structure of the oxide, and the element X being contained in the oxide in a greater amount than carbon and being an element that constitutes the skeleton of the oxide together with oxygen.

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

3. A quantum dot dispersion according to claim 1 or 2, which contains a compound containing an X-O-X bond (where O is an oxygen element and X is the element X), and the atom of the element X in the X-O-X bond is bonded to a hydrocarbon group whose number is equal to the valence of the atom of the element X minus 1.

4. The quantum dot dispersion according to any one of claims 1 to 3, wherein the element X is silicon.

5. A quantum dot dispersion liquid according to any one of claims 1 to 4, wherein the hydrocarbon group is a saturated hydrocarbon group.

6. A quantum dot dispersion liquid according to any one of claims 1 to 5, wherein the hydrocarbon group is a linear alkyl group.

7. A quantum dot dispersion liquid according to any one of claims 1 to 6, wherein the number of carbon atoms contained in the hydrocarbon group is 5 or less.

8. A quantum dot dispersion liquid according to any one of claims 1 to 7, wherein the oxide contains more hydrocarbon groups than O-H groups.

9. The oxide is X—(CH ２ ) 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). The quantum dot dispersion liquid according to any one of claims 1 to 8, 10. A quantum dot dispersion liquid according to any one of claims 1 to 9, 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) 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).

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 adduct of the quantum dots or as a matrix filling at least a portion of the gaps between a plurality of the quantum dots, wherein, in a portion of a terminal portion of a chemical structure of the oxide, an atom of element X is bonded to a hydrocarbon group and one oxygen atom whose valence is minus one of the atoms of element X, the hydrocarbon group being at the terminal portion of the chemical structure of the oxide, and wherein the element X is contained in the oxide in a greater amount than carbon and is an element that constitutes the skeleton of the oxide together with oxygen.

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 the light-emitting layer contains a compound containing an X-O-X bond (where O is an oxygen element and X is the element X), and the element X in the X-O-X bond is bonded to a hydrocarbon group whose number is equal to the valence of the atom of the element X minus 1.

14. The light-emitting device according to any one of claims 11 to 13, wherein the element X is silicon.

15. The light-emitting element according to any one of claims 11 to 14, wherein the hydrocarbon group is a saturated hydrocarbon group.

16. The light-emitting element according to any one of claims 11 to 15, wherein the hydrocarbon group is a linear alkyl group.

17. The light-emitting device according to any one of claims 11 to 16, wherein the hydrocarbon group contains five or less carbon atoms.

18. The light-emitting element according to any one of claims 11 to 17, wherein the oxide contains more hydrocarbon groups than 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. A light-emitting element according to any one of claims 11 to 19, 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) 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).

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 method for manufacturing a light-emitting element, comprising: a step of forming a light-emitting layer containing a plurality of quantum dots and an oxide of element X; in the step of forming the light-emitting layer, the oxide is formed, the oxide containing one hydrocarbon group and one oxygen atom bonded to the atom of element X whose valence is minus one of the atoms of element X; and the element X is contained in the oxide in a greater amount than carbon and is an element that constitutes the skeleton of the oxide together with oxygen.

23. The method for manufacturing a light-emitting element according to claim 22, 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 solution containing a terminating agent.

24. A method for manufacturing a light-emitting element as described in claim 23, 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 on the shorter wavelength side 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 contacting the first quantum dot layer and the second quantum dot layer with a solution containing the terminating agent.

25. The method for manufacturing a light-emitting element according to claim 23 or 24, wherein the terminating agent contains one HO-X bond (H is a hydrogen element, O is an oxygen element, and X is the element X), and the atom of the element X in the HO-X bond is bonded to a hydrocarbon group whose number is one less than the valence of the atom of the element X.

26. The method for manufacturing a light-emitting element according to claim 23 or 24, wherein the terminating agent contains one Si—NH—Si bond, and each of the two Si atoms in the Si—NH—Si bond is bonded to three alkyl groups.

27. The method for manufacturing a light-emitting element according to any one of claims 23, 24, and 26, wherein the terminating agent is hexamethyldisilazane.

28. A method for manufacturing a light-emitting element according to claim 23, 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 with a first solution containing a first terminating agent that is the terminating agent; 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 with a second solution containing a second terminating agent that is the terminating agent; 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.

29. The method for manufacturing a light-emitting device according to claim 28, wherein the composition of the first solution is different from the composition of the second solution.

30. A method for manufacturing a light-emitting element as described in claim 22, wherein in the step of forming the light-emitting layer, the light-emitting layer is formed using a third solution containing a plurality of quantum dots containing the oxide as an additive, a terminating agent, and a solvent.

31. A method for manufacturing a light-emitting device according to any one of claims 22 to 30, wherein the element X is silicon.

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