Semiconductor nanoparticle composite, semiconductor nanoparticle composite dispersion, semiconductor nanoparticle composite composition, and semiconductor nanoparticle composite cured film

Abstract

To provide a semiconductor nanoparticle composite body which can be dispersed in a polar dispersant with high mass fraction while maintaining a high fluorescence quantum efficiency (QY).SOLUTION: A semiconductor nanoparticle composite body according to one embodiment of the invention is a semiconductor nanoparticle composite body in which two or more kinds of ligands including an aliphatic thiol ligand and a polar ligand are coordinated to the surface of a semiconductor nanoparticle. The ligands are composed of an organic group and a coordinating group, and in the aliphatic thiol ligand, the organic group is an aliphatic hydrocarbon group and the coordinating group is a mercapto group, the polar ligand includes a hydrophilic functional group in the organic group, and the hydrophilic functional group includes at least one selected from a hydroxy group, a carboxy group, a carbonyl group, an amino group, an ether bond, an ester bond and a siloxane bond, and the mass ratio of the aliphatic thiol ligand to the polar ligand ((aliphatic thiol ligand) / (polar ligand)) is 0.05-1.00.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a semiconductor nanoparticle composite, a semiconductor nanoparticle composite dispersion, a semiconductor nanoparticle composite composition, and a semiconductor nanoparticle composite cured film. This application claims priority based on Japanese Patent Application No. 2019-103239 filed on May 31, 2019, and Japanese Patent Application No. 2019-103240 filed on the same day, and incorporates by reference all of the contents of said Japanese patent application. [Background technology]

[0002] Semiconductor nanoparticles that are small enough to exhibit the quantum confinement effect have a band gap that depends on their particle size. Excitons formed within semiconductor nanoparticles by means of photoexcitation, charge injection, or other methods recombine to emit photons with an energy that corresponds to the band gap. Therefore, by appropriately selecting the composition and particle size of the semiconductor nanoparticles, it is possible to obtain light emission at a desired wavelength.

[0003] In the early stages of research into semiconductor nanoparticles, the focus was on elements containing Cd and Pb. However, because Cd and Pb are regulated substances under the Restrictions on the Use of Certain Hazardous Substances Act, research has been focused in recent years on non-Cd-based and non-Pb-based semiconductor nanoparticles.

[0004] Semiconductor nanoparticles have been used in a variety of applications, including displays, biolabeling, and solar cells. In particular, semiconductor nanoparticles have begun to be used as wavelength conversion layers in films for displays. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-136498 [Non-patent literature]

[0006] [Non-Patent Document 1] Takashi Jin, "Semiconductor Quantum Dots, Their Synthesis and Applications in Life Sciences," Production and Technology, Vol. 63, No. 2, pp. 58-63, 2011 [Non-patent document 2] Fabien Dubois et al, “A Versatile Strategy for Quantum Dot Ligand Exchange” J.AM.CHEM.SOC Vol.129, No.3, p.482-483, 2007 [Non-patent document 3] Boon-Kin Pong et al, “Modified Ligand-Exchange for Efficient Solubilization of CdSe / ZnS Quantum Dots in Water: A Procedure Guided by Computational Studies” Langmuir Vol.24, No.10, p.5270-5276, 2008 [Non-patent document 4] Samsulida Abd. Rahman et al, “Thiolate-Capped CdSe / ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose” Sensors Vol.17, No.7, p.1537, 2017 [Non-Patent Document 5] Whitney Nowak Wenger et al, “Functionalization of Cadmium Selenide Quantum Dots with Poly(ethylene glycol): Ligand Exchange, Surface Coverage, and Dispersion Stability” Langmuir, Vol.33, No.33, pp8239-8245, 2017 Summary of the Invention [Problem to be solved by the invention]

[0007] Semiconductor nanoparticles and semiconductor nanoparticle composites can generally be dispersed in a dispersion medium, prepared as a dispersion, and applied in various fields. In particular, for practical use, it is desirable to disperse them in a dispersion medium with an SP value of 8.5 or more. Semiconductor nanoparticles and semiconductor nanoparticle composites synthesized in nonpolar dispersion media are highly hydrophobic and therefore easily dispersible in nonpolar dispersion media, but dispersion in polar dispersion media with an SP value of 8.5 or higher was difficult.

[0008] Semiconductor nanoparticles and semiconductor nanoparticle composites synthesized in nonpolar dispersion media are presumed to have weak dipole-dipole forces and hydrogen bonding forces. Therefore, among polar dispersion media with SP values ​​of 8.5 or higher, semiconductor nanoparticles can be dispersed in toluene and chloroform, which have weak dipole-dipole forces and hydrogen bonding forces, just like semiconductor nanoparticles synthesized in organic solvents. However, these polar dispersion media are highly toxic and therefore not practical.

[0009] Known methods for dispersing semiconductor nanoparticles in polar dispersion media with an SP value of 8.5 or higher include the ligand exchange method and the encapsulation method. The ligand exchange method is a method in which the ligand contained in a semiconductor nanoparticle composite obtained by binding a ligand to the surface of semiconductor nanoparticles is replaced with a ligand having a hydrophilic group. The semiconductor nanoparticle composite obtained in this manner can be dispersed in a polar dispersion medium. However, the semiconductor nanoparticle composites disclosed in Non-Patent Documents 1 to 5 and Patent Document 1 have the problem that, although the semiconductor nanoparticles can be dispersed in a polar dispersion medium, the luminescence efficiency is reduced. The encapsulation method involves further coating the semiconductor nanoparticle composites obtained by binding ligands to the surfaces of semiconductor nanoparticles with an amphiphilic polymer. However, the encapsulation method increases the amount of dispersant relative to the semiconductor nanoparticles, making it difficult to achieve a high mass fraction of semiconductor nanoparticles.

[0010] Therefore, in order to solve the above problems, an object of the present invention is to provide a semiconductor nanoparticle composite that can be dispersed at a high mass fraction in a polar dispersion medium while maintaining a high fluorescence quantum efficiency (QY). [Means for solving the problem]

[0011] The semiconductor nanoparticle composite according to the present invention is A semiconductor nanoparticle composite in which two or more types of ligands, including an aliphatic thiol ligand and a polar ligand, are coordinated to the surface of a semiconductor nanoparticle, the ligand comprises an organic group and a coordinating group; The aliphatic thiol ligand has an aliphatic hydrocarbon group as the organic group and a mercapto group as the coordinating group, The polar ligand includes a hydrophilic functional group in the organic group, the hydrophilic functional group includes at least one of a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ether bond, an ester bond, and a siloxane bond; the mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) is 0.05 to 1.00; A semiconductor nanoparticle composite. In this application, the range indicated by "to" is a range that includes the numbers on both ends of the range. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide a semiconductor nanoparticle composite that can be dispersed at a high mass fraction in a polar dispersion medium while maintaining a high fluorescence quantum efficiency (QY). [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a graph showing the results of 1H-NMR analysis of semiconductor nanoparticle composites in Examples. [Figure 2] 1 is a graph showing the results of 1H-NMR analysis of the ligands used in the examples. DETAILED DESCRIPTION OF THE INVENTION

[0014] (Semiconductor nanoparticle composite) The semiconductor nanoparticle composite according to the present invention has two or more types of ligands coordinated to the surface of semiconductor nanoparticles, has high light-emitting properties, and can be dispersed at a high mass fraction in a dispersion medium or a cured film. In the present invention, the semiconductor nanoparticle composite is a semiconductor nanoparticle composite having light-emitting properties. The semiconductor nanoparticle composite of the present invention is a particle that absorbs light of 340 nm to 480 nm and emits light with an emission peak wavelength of 400 nm to 750 nm.

[0015] The full width at half maximum (FWHM) of the emission spectrum of the semiconductor nanoparticle composite is preferably 40 nm or less, and more preferably 35 nm or less. When the full width at half maximum of the emission spectrum is in this range, color mixing can be reduced when the semiconductor nanoparticle composite is applied to displays and the like. The fluorescence quantum efficiency (QY) of the semiconductor nanoparticle composite is preferably 80% or more, and more preferably 85% or more. When the fluorescence quantum efficiency of the semiconductor nanoparticle composite is 80% or more, color conversion can be performed more efficiently. In the present invention, the fluorescence quantum efficiency of the semiconductor nanoparticle composite can be measured using a quantum efficiency measurement system.

[0016] -Semiconductor nanoparticles- The semiconductor nanoparticles constituting the semiconductor nanoparticle composite are not particularly limited as long as they satisfy the aforementioned luminescence characteristics, such as the fluorescence quantum efficiency and half-width. They may be particles made of a single semiconductor or particles made of two or more different semiconductors. In the case of particles made of two or more different semiconductors, the semiconductors may form a core-shell structure. For example, the particles may be core-shell particles having a core containing a group III element and a group V element and a shell containing group II and group VI elements that covers at least a portion of the core. The shell may have multiple shells of different compositions, or may have one or more gradient shells in which the ratio of the elements constituting the shell changes within the shell.

[0017] Specific examples of Group III elements include In, Al, and Ga. Specific examples of Group V elements include P, N and As. The composition of the core is not particularly limited, but InP is preferred from the viewpoint of light emission characteristics.

[0018] The Group II elements are not particularly limited, but examples thereof include Zn and Mg. Examples of Group VI elements include S, Se, Te, and O. The composition of the shell is not particularly limited, but from the viewpoint of quantum confinement effect, ZnS, ZnSe, ZnSeS, ZnTeS, ZnTeSe, etc. In particular, when Zn element is present on the surface of the semiconductor nanoparticles, the effects of the present invention can be more effectively exhibited.

[0019] When multiple shells are present, it is sufficient that at least one shell has the aforementioned composition. Furthermore, when a shell has a gradient type in which the ratio of elements constituting the shell changes within the shell, the shell does not necessarily have to have the composition indicated. In the present invention, whether the shell covers at least a portion of the core and the element distribution inside the shell can be confirmed by, for example, composition analysis using energy dispersive X-ray spectroscopy (TEM-EDX) with a transmission electron microscope.

[0020] In the present invention, the average particle size of semiconductor nanoparticles can be measured by calculating the particle sizes of 10 or more particles in an image of particles observed using a transmission electron microscope (TEM) as the equivalent circle diameter (Heywood diameter). From the viewpoint of luminescence characteristics, a narrow particle size distribution is preferable, and the coefficient of variation of particle size is preferably 15% or less. Here, the coefficient of variation is defined as "coefficient of variation = standard deviation of particle size / average particle size." A coefficient of variation of 15% or less is an indicator that semiconductor nanoparticles with a narrower particle size distribution have been obtained.

[0021] An example of a method for producing semiconductor nanoparticles will be disclosed below. The core of the semiconductor nanoparticle can be formed by mixing a Group III precursor, a Group V precursor, and, if necessary, an additive in a solvent and heating the resulting precursor mixture. Coordinating and non-coordinating solvents are used, including 1-octadecene, hexadecane, squalane, oleylamine, trioctylphosphine, and trioctylphosphine oxide. Group III precursors include, but are not limited to, acetates, carboxylates, and halides containing the Group III elements. Examples of Group V precursors include, but are not limited to, organic compounds and gases containing the Group V elements. When the precursor is a gas, the core can be formed by injecting the gas into a precursor mixture containing other gases and allowing it to react.

[0022] The semiconductor nanoparticles may contain one or more elements other than Group III and Group V elements, as long as the effects of the present invention are not impaired. In this case, a precursor of the element may be added during core formation. Examples of additives include, but are not limited to, dispersants such as carboxylic acids, amines, thiols, phosphines, phosphine oxides, phosphinic acids, and phosphonic acids. The dispersant may also serve as a solvent. After the core of the semiconductor nanoparticle is formed, a halide can be added as needed to improve the light-emitting properties of the semiconductor nanoparticle.

[0023] In one embodiment, a metal precursor solution prepared by adding an In precursor and, if necessary, a dispersant to a solvent is mixed under vacuum, and the mixture is heated at 100°C to 300°C for 6 to 24 hours. After that, a P precursor is added and the mixture is heated at 200°C to 400°C for 3 to 60 minutes, followed by cooling. A halogen precursor is then added and the mixture is heated at 25°C to 300°C, preferably 100°C to 300°C, more preferably 150°C to 280°C, to obtain a core particle dispersion containing core particles.

[0024] By adding a shell-forming precursor to the synthesized core particle dispersion, the semiconductor nanoparticles can adopt a core-shell structure, which can enhance the fluorescence quantum efficiency (QY) and stability. The elements that make up the shell are thought to have an alloy, heterostructure, or amorphous structure on the surface of the core particle, but it is also possible that some of them migrate to the inside of the core particle by diffusion.

[0025] The added shell-forming element is present mainly near the surface of the core particle and plays a role in protecting the semiconductor nanoparticles from external factors. In the core-shell structure of the semiconductor nanoparticles, the shell preferably covers at least a part of the core, and more preferably uniformly covers the entire surface of the core particle.

[0026] In one embodiment, a Zn precursor and a Se precursor are added to the aforementioned core particle dispersion, followed by heating at 150° C. to 300° C., preferably 180° C. to 250° C., and then a Zn precursor and a S precursor are added, followed by heating at 200° C. to 400° C., preferably 250° C. to 350° C. This allows core-shell semiconductor nanoparticles to be obtained. Here, although not particularly limited, examples of Zn precursors that can be used include carboxylates such as zinc acetate, zinc propionate, and zinc myristate, halides such as zinc chloride and zinc bromide, and organic salts such as diethylzinc. As the Se precursor, phosphine selenides such as tributylphosphine selenide, trioctylphosphine selenide, and tris(trimethylsilyl)phosphine selenide, selenols such as benzeneselenol and selenocysteine, and selenium / octadecene solution can be used. As the S precursor, phosphine sulfides such as tributylphosphine sulfide, trioctylphosphine sulfide, and tris(trimethylsilyl)phosphine sulfide, thiols such as octanethiol, dodecanethiol, and octadecanethiol, and sulfur / octadecene solution can be used. The shell precursors may be mixed in advance and added all at once or in multiple portions, or each may be added separately all at once or in multiple portions. When the shell precursors are added in multiple portions, heating may be performed at different temperatures after each addition of the shell precursors.

[0027] In the present invention, the method for producing semiconductor nanoparticles is not particularly limited, and in addition to the methods described above, any conventional production method such as the hot injection method, the homogeneous solvent method, the reverse micelle method, or the CVD method may be employed.

[0028] -Ligand- In the present invention, the semiconductor nanoparticle composite has a ligand coordinated to the surface of the semiconductor nanoparticle. The term "coordination" used here means that the ligand chemically influences the surface of the semiconductor nanoparticle. The ligand may be bonded to the surface of the semiconductor nanoparticle by a coordinate bond or any other bonding mode (e.g., covalent bond, ionic bond, hydrogen bond, etc.), or, if at least a portion of the surface of the semiconductor nanoparticle has a ligand, the ligand may not necessarily form a bond.

[0029] In the present invention, the ligands coordinated to the semiconductor nanoparticles consist of an organic group and a coordinating group. Two or more types of ligands, including an aliphatic thiol ligand and a polar ligand, are coordinated to the surface of the semiconductor nanoparticles. The organic group of the aliphatic thiol ligand is an aliphatic hydrocarbon group, and the coordinating group is a mercapto group. The organic group of the polar ligand contains a hydrophilic functional group.

[0030] The organic group of the aliphatic thiol ligand is preferably an aliphatic hydrocarbon group having 6 to 14 carbon atoms. The structure of the organic group of the aliphatic thiol ligand may be linear, branched, or non-aromatic, and high fluorescence quantum efficiency can be obtained when the carbon number of the organic group is in the range of 6 to 14. The aliphatic thiol ligand is preferably one or more selected from the group consisting of hexanethiol, octanethiol, decanethiol, and dodecanethiol. By using these ligands as the aliphatic thiol ligand, higher fluorescence quantum efficiency can be obtained. Since the coordinating group of the aliphatic thiol ligand is a mercapto group, the aliphatic thiol ligand can be tightly coordinated to the surface of the semiconductor nanoparticle.

[0031] The polar ligand has a hydrophilic functional group in its organic group. The hydrophilic functional group may be, for example, at least one of a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ether bond, an ester bond, and a siloxane bond. Having a hydrophilic functional group in the organic group of the polar ligand allows dispersion in a polar dispersion medium. In particular, when the organic group of the polar ligand contains an ether bond, high fluorescence quantum efficiency is obtained and dispersion in a wide range of polar dispersion media is possible. Dispersibility in a wide range of polar dispersion media means that when semiconductor nanoparticle composites in which ligands are coordinated on the surface of semiconductor nanoparticles are incorporated into a resin, there is almost no reaction between the ligand and the resin, which leads to a wider range of resin options.

[0032] The coordinating group of the polar ligand is preferably a mercapto group or a carboxyl group, and particularly preferably a mercapto group, in view of the strength of coordination to the semiconductor nanoparticles.

[0033] The molecular weight of the polar ligand is preferably 50 or more and 600 or less, and more preferably 50 or more and 450 or less. Use of a ligand with a molecular weight of 600 or less prevents the semiconductor nanoparticle composite from increasing in size and volume, and when the semiconductor nanoparticle composite is applied to a dispersion, composition, cured film, etc., it becomes easier to increase the mass fraction of the semiconductor nanoparticle composite relative to these. On the other hand, when the molecular weight is 50 or more, the effect of steric hindrance is fully exerted, and the occurrence of aggregation, etc. can be suppressed. By setting the molecular weight of the polar ligand in the semiconductor nanoparticle composite within the above-mentioned range, the semiconductor nanoparticle composite can be dispersed at a high mass fraction in an organic dispersion medium, which will be described later.

[0034] The mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) may be 0.05 to 1.00. When the mass ratio is within this range, high fluorescence quantum efficiency can be obtained. If the mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) exceeds 1.00, it may be difficult to disperse the aliphatic thiol ligand in a polar dispersion medium with an SP value of 8.5 or more. The mass ratio (aliphatic thiol ligand / polar ligand) is more preferably 0.10 to 1.00, and even more preferably 0.20 to 0.80.

[0035] Furthermore, when the ligands include ligands other than the aliphatic thiol ligand and the polar ligand, the total mass fraction of the aliphatic thiol ligand and the polar ligand relative to all ligands is preferably 0.7 or more. By setting the mass fraction to 0.7 or more, the semiconductor nanoparticle composite can be easily dispersed in a polar dispersion medium and the fluorescence quantum efficiency can be prevented from decreasing. More preferably, the total mass fraction of the aliphatic thiol ligand and the polar ligand relative to all ligands is 0.8 or more.

[0036] The mass ratio of the aliphatic thiol ligand to the polar ligand coordinated to the surface of the semiconductor nanoparticles can be quantified using 1H-NMR. The resulting semiconductor nanoparticle composite is dispersed in a heavy solvent, and electromagnetic waves are applied in a magnetic field to induce 1H nuclear magnetic resonance. The resulting free induction decay signal is then subjected to Fourier analysis to obtain an 1H-NMR spectrum. The 1H-NMR spectrum gives characteristic signals at positions corresponding to the structure of the ligand species, and the type of each ligand can be identified and its ratio calculated from the position and integrated intensity ratio of these signals. Examples of heavy solvents include CDCl3, acetone-d6, and N-hexane-D14.

[0037] (Method of manufacturing semiconductor nanoparticle composite) An example of a method for producing a semiconductor nanoparticle composite will be disclosed below. There are no limitations on the method for coordinating the ligand to the semiconductor nanoparticles, but a ligand exchange method utilizing the coordination power of the ligand can be used. Specifically, semiconductor nanoparticles in which the organic compound used in the process of producing the semiconductor nanoparticles described above is coordinated to the surface of the semiconductor nanoparticles are contacted with the target ligand in the liquid phase, thereby obtaining a semiconductor nanoparticle composite in which the target ligand is coordinated to the surface of the semiconductor nanoparticles. In this case, a liquid phase reaction using a solvent as described below is usually performed, but if the ligand used is liquid under the reaction conditions, it is also possible to use the ligand itself as the solvent and adopt a reaction format in which no other solvent is added.

[0038] Furthermore, if a purification step and a redispersion step as described below are carried out before the ligand is coordinated, the desired ligand can be easily coordinated. When a non-coordinating solvent is used during the synthesis of semiconductor nanoparticles, the generation of defects on the surface of the semiconductor nanoparticles when the desired ligand is coordinated can be minimized, and a decrease in the fluorescence quantum efficiency can be prevented.

[0039] In one embodiment, the semiconductor nanoparticle-containing dispersion after production of the semiconductor nanoparticles is purified and redispersed, and then a solvent containing an aliphatic thiol ligand is added, followed by further addition of a solvent containing a polar ligand, and the mixture is stirred at 50°C to 200°C for 1 minute to 120 minutes in a nitrogen atmosphere to obtain the desired semiconductor nanoparticle composite. The aliphatic thiol ligand and the polar ligand may be added simultaneously.

[0040] Semiconductor nanoparticles and semiconductor nanoparticle composites can be purified as follows. In one embodiment, the semiconductor nanoparticle composites can be precipitated from the dispersion by adding a polarity-reversing solvent such as acetone. The precipitated semiconductor nanoparticle composites can be recovered by filtration or centrifugation, while the supernatant containing unreacted starting materials and other impurities can be discarded or recycled. The precipitated semiconductor nanoparticle composites can then be washed with additional dispersant and redispersed. This purification process can be repeated, for example, 2 to 4 times, or until the desired purity is reached. In the present invention, the method for purifying the semiconductor nanoparticle composite is not particularly limited, and in addition to the methods described above, for example, aggregation, liquid-liquid extraction, distillation, electrodeposition, size exclusion chromatography and / or ultrafiltration, or any other method can be used alone or in combination.

[0041] (Semiconductor nanoparticle composite dispersion) The semiconductor nanoparticle composite contained in the semiconductor nanoparticle composite dispersion of the present invention can adopt the configuration of the semiconductor nanoparticle composite of the present invention described above. In the present invention, a state in which the semiconductor nanoparticle composite is dispersed in a dispersion medium refers to a state in which, when the semiconductor nanoparticle composite and the dispersion medium are mixed, the semiconductor nanoparticle composite does not precipitate or does not remain as visible turbidity (cloudiness). Note that a semiconductor nanoparticle composite dispersed in a dispersion medium is referred to as a semiconductor nanoparticle composite dispersion.

[0042] The semiconductor nanoparticle composite of the present invention can be dispersed in an organic dispersion medium to form a semiconductor nanoparticle composite dispersion liquid. The semiconductor nanoparticle composite of the present invention can be dispersed in an organic dispersion medium having an SP value of 8.5 or more, and further in an organic dispersion medium having an SP value of 9.0 or more, or an organic dispersion medium having an SP value of 10.0 or more, to form a semiconductor nanoparticle composite dispersion liquid. The SP value here is the Hildebrand solubility parameter, which is a value calculated from the Hansen solubility parameter, which can be determined using values ​​in handbooks, such as "Hansen Solubility Parameters: A User's Handbook", 2nd Edition, C. M. Hansen (2007), or the Practice (HSPiP) program (2nd Edition) provided by Hanson and Abbot et al.

[0043] By adjusting the mass ratio of the aliphatic thiol ligand to the polar ligand as described above, it becomes possible to disperse the semiconductor nanoparticle composite in one or more organic dispersion media selected from the group consisting of hexane, acetone, propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME), isopropyl alcohol (IPA), isobornyl acrylate (IBOA), ethanol, and methanol. In particular, polar organic dispersion media such as alcohols, ketones, esters, glycol ethers, and glycol ether esters can be selected as the organic dispersion media. Dispersion in these organic dispersion media allows the semiconductor nanoparticle composite to maintain its dispersibility when applied to cured films and resins, as described below. In particular, PGMEA and PGME are commonly used as diluents in photoresists, and the ability to disperse semiconductor nanoparticle composites in PGMEA and PGME allows for widespread application in the photoresist field.

[0044] When the semiconductor nanoparticle composite has the above-described configuration, the semiconductor nanoparticle composite can be dispersed in an organic dispersion medium at a high mass fraction, and as a result, the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite dispersion can be made 20 mass% or more, further 25 mass% or more, and even 35 mass% or more.

[0045] Furthermore, in the present invention, a monomer can be selected as the dispersion medium for the semiconductor nanoparticle composite dispersion. The monomer is not particularly limited, but is preferably a (meth)acrylic monomer, which allows for a wide range of applications for the semiconductor nanoparticles. Depending on the application of the semiconductor nanoparticle composite dispersion, the (meth)acrylic monomer may be selected from methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, isobutyl (meth)acrylate, isoamyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, dodecyl (meth)acrylate, isodecyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 3,5,5-trimethylcyclohexanol (meth)acrylate, dicyclopentanyl (meth)acrylate, dicyclopentenyl (meth)acrylate, methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxytriethylene glycol acrylate, 2-ethylhexyl diglycol acrylate, methoxypolyethylene glycol acrylate, methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxytriethylene glycol acrylate, 2-ethylhexyl diglycol acrylate, methoxypolyethylene glycol acrylate, methoxyethyl (meth)acrylate, methyl ... Dipropylene glycol acrylate, phenoxyethyl (meth)acrylate, 2-phenoxydiethylene glycol (meth)acrylate, 2-phenoxypolyethylene glycol (meth)acrylate (n≒2), tetrahydrofurfuryl (meth)acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, dicyclopentanyloxyl ether ethyl (meth)acrylate, isobornyloxylethyl (meth)acrylate, adamantyl (meth)acrylate, dimethyladamantyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, benzyl (meth)acrylate, ω-carboxy-polycaprolactone (n≒2) monoacrylate, 2-hydroxy-3-phenoxypropyl acrylate, 2-hydroxy-3-phenoxyethyl (meth)acrylate, (2-methyl-2-ethyl-1,The (meth)acrylic monomers may be selected from (meth)acrylic monomers such as (3-dioxolan-4-yl)methyl (meth)acrylate, (3-ethyloxetan-3-yl)methyl (meth)acrylate, o-phenylphenolethoxy (meth)acrylate, dimethylamino (meth)acrylate, diethylamino (meth)acrylate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl hexahydrophthalate, glycidyl (meth)acrylate, 2-(meth)acryloyloxyethyl phosphate, acryloylmorpholine, dimethylacrylamide, dimethylaminopropyl acrylamide, isopropyl acrylamide, diethyl acrylamide, hydroxyethyl acrylamide, and N-acryloyloxyethyl hexahydrophthalimide. These may be used alone or in combination of two or more. In particular, the acrylic monomer is preferably one or a mixture of two or more selected from lauryl (meth)acrylate and 1,6-hexadiol di(meth)acrylate, depending on the application of the semiconductor nanoparticle composite dispersion. A prepolymer can be selected as the dispersion medium for the semiconductor nanoparticle composite dispersion liquid. The prepolymer is not particularly limited, but examples thereof include acrylic resin prepolymers, silicone resin prepolymers, and epoxy resin prepolymers.

[0046] The semiconductor nanoparticle composite dispersion of the present invention preferably has a fluorescence quantum efficiency (QY) of 80% or more, more preferably 85% or more. When the semiconductor nanoparticle composite dispersion has a fluorescence quantum efficiency of 80% or more, color conversion can be performed more efficiently. The fluorescence quantum efficiency of the semiconductor nanoparticle composite dispersion can be measured using a quantum efficiency measurement system.

[0047] (Semiconductor nanoparticle composite composition) In the present invention, a monomer or prepolymer can be selected as the dispersion medium for the semiconductor nanoparticle composite dispersion to form the semiconductor nanoparticle composite composition. The monomer or prepolymer is not particularly limited, but examples thereof include radical polymerizable compounds containing ethylenically unsaturated bonds, siloxane compounds, epoxy compounds, isocyanate compounds, and phenol derivatives. Furthermore, a crosslinking agent may be added to the semiconductor nanoparticle composite composition. The crosslinking agent is selected from polyfunctional (meth)acrylates, polyfunctional silane compounds, polyfunctional amines, polyfunctional carboxylic acids, polyfunctional thiols, polyfunctional alcohols, polyfunctional isocyanates, and the like, depending on the type of monomer in the semiconductor nanoparticle composite composition. Furthermore, the semiconductor nanoparticle composite composition may further contain various organic solvents that do not affect curing, such as aliphatic hydrocarbons such as pentane, hexane, cyclohexane, isohexane, heptane, octane, and petroleum ether, alcohols, ketones, esters, glycol ethers, glycol ether esters, aromatic hydrocarbons such as benzene, toluene, xylene, and mineral spirits, and alkyl halides such as dichloromethane and chloroform. The above organic solvents can be used not only to dilute the semiconductor nanoparticle composite composition, but also as an organic dispersion medium. That is, the semiconductor nanoparticle composite of the present invention can be dispersed in the above organic solvent to form a semiconductor nanoparticle composite dispersion.

[0048] Furthermore, the semiconductor nanoparticle composite composition may contain appropriate initiators, scattering agents, catalysts, binders, surfactants, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents, dispersants, and the like, depending on the type of monomer in the semiconductor nanoparticle composite composition. Furthermore, to improve the optical properties of the semiconductor nanoparticle composite composition or the semiconductor nanoparticle composite cured film described below, the semiconductor nanoparticle composite composition may contain a scattering agent. The scattering agent is a metal oxide such as titanium oxide or zinc oxide, and the particle size thereof is preferably 100 nm to 500 nm. From the viewpoint of scattering effect, the particle size of the scattering agent is more preferably 200 nm to 400 nm. The inclusion of a scattering agent improves the absorbance by about two times. The content of the scattering agent is preferably 2% by mass to 30% by mass of the composition, and more preferably 5% by mass to 20% by mass from the viewpoint of maintaining the patternability of the composition.

[0049] The configuration of the semiconductor nanoparticle composite of the present invention allows the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite composition to be 30 mass% or more. By setting the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite composition to 30 mass% to 95 mass%, the semiconductor nanoparticle composites and semiconductor nanoparticles can be dispersed at a high mass fraction even in the cured film described below.

[0050] When the semiconductor nanoparticle composite composition of the present invention is formed into a 10 μm film, the absorbance of light with a wavelength of 450 nm from the normal direction of the film is preferably 1.0 or more, more preferably 1.3 or more, and even more preferably 1.5 or more. This allows for efficient absorption of backlight light, thereby enabling the thickness of the cured film described below to be reduced, and the device to which it is applied to be made smaller.

[0051] (Diluted Composition) The diluted composition is obtained by diluting the above-mentioned semiconductor nanoparticle composite composition of the present invention with an organic solvent. The organic solvent used to dilute the semiconductor nanoparticle composite composition is not particularly limited, and examples include aliphatic hydrocarbons such as pentane, hexane, cyclohexane, isohexane, heptane, octane, and petroleum ether, alcohols, ketones, esters, glycol ethers, glycol ether esters, aromatic hydrocarbons such as benzene, toluene, xylene, and mineral spirits, and alkyl halides such as dichloromethane and chloroform. Among these, glycol ethers and glycol ether esters are preferred from the viewpoints of solubility in a wide range of resins and film uniformity upon application.

[0052] (Semiconductor nanoparticle composite cured film) In the present invention, the term "semiconductor nanoparticle composite cured film" refers to a film containing a semiconductor nanoparticle composite and that has been cured. The semiconductor nanoparticle composite cured film can be obtained by curing the semiconductor nanoparticle composite composition or diluted composition described above into a film. The semiconductor nanoparticle composite cured film contains semiconductor nanoparticles, ligands coordinated to the surfaces of the semiconductor nanoparticles, and a polymer matrix. The polymer matrix is ​​not particularly limited, and examples thereof include (meth)acrylic resin, silicone resin, epoxy resin, silicone resin, maleic acid resin, butyral resin, polyester resin, melamine resin, phenolic resin, and polyurethane resin. A semiconductor nanoparticle composite cured film may be obtained by curing the aforementioned semiconductor nanoparticle composite composition. The semiconductor nanoparticle composite cured film may further contain a crosslinking agent.

[0053] The method for curing the film is not particularly limited, but the film can be cured by a curing method suitable for the composition that constitutes the film, such as heat treatment or ultraviolet treatment. The semiconductor nanoparticles and the ligands coordinated to the surfaces of the semiconductor nanoparticles contained in the semiconductor nanoparticle composite cured film preferably constitute the semiconductor nanoparticle composite described above. By configuring the semiconductor nanoparticle composite contained in the semiconductor nanoparticle composite cured film of the present invention as described above, it is possible to disperse the semiconductor nanoparticle composite in the cured film at a higher mass fraction. The mass fraction of the semiconductor nanoparticles in the semiconductor nanoparticle composite cured film is preferably 30 mass% or more, and more preferably 40 mass% or more. However, if it is 70 mass% or more, the composition that constitutes the film will be reduced, making it difficult to cure and form the film.

[0054] The semiconductor nanoparticle composite cured film of the present invention contains a high mass fraction of semiconductor nanoparticle composite, thereby enabling the semiconductor nanoparticle composite cured film to have increased absorbance. When the semiconductor nanoparticle composite cured film has a thickness of 10 μm, the absorbance of light with a wavelength of 450 nm from the normal direction of the semiconductor nanoparticle composite cured film is preferably 1.0 or more, more preferably 1.3 or more, and even more preferably 1.5 or more.

[0055] Furthermore, since the semiconductor nanoparticle composite cured film of the present invention contains a semiconductor nanoparticle composite with high luminescence properties, it is possible to provide a semiconductor nanoparticle composite cured film with high luminescence properties. The fluorescence quantum efficiency of the semiconductor nanoparticle composite cured film is preferably 70% or more, and more preferably 80% or more.

[0056] In order to miniaturize devices to which the semiconductor nanoparticle composite cured film is applied, the thickness of the semiconductor nanoparticle composite cured film is preferably 50 μm or less, more preferably 20 μm or less, and even more preferably 10 μm or less.

[0057] (Semiconductor nanoparticle composite patterned film and display element) The semiconductor nanoparticle composite patterned film can be obtained by patterning the semiconductor nanoparticle composite composition or diluted composition into a film. The method for patterning the semiconductor nanoparticle composite composition or diluted composition is not particularly limited, and examples thereof include spin coating, bar coating, inkjet printing, screen printing, and photolithography. The display element uses the semiconductor nanoparticle composite patterned film. For example, by using the semiconductor nanoparticle composite patterned film as a wavelength conversion layer, a display element having excellent fluorescence quantum efficiency can be provided.

[0058] The semiconductor nanoparticle composite dispersion of the present invention employs the following configuration. (1) A dispersion in which a semiconductor nanoparticle composite is dispersed in an organic dispersion medium, the semiconductor nanoparticle composite comprises two or more types of ligands including an aliphatic thiol ligand and a polar ligand, and semiconductor nanoparticles having the ligands coordinated to the surface thereof; the ligand comprises an organic group and a coordinating group; The polar ligand includes a hydrophilic functional group in the organic group, The SP value of the organic dispersion medium is 8.5 or more. Semiconductor nanoparticle composite dispersion. (2) The SP value of the organic dispersion medium is 9.0 or more. The semiconductor nanoparticle composite dispersion liquid according to (1) above. (3) The organic dispersion medium is one or a mixed dispersion medium of two or more selected from the group consisting of alcohols, ketones, esters, glycol ethers, and glycol ether esters. The semiconductor nanoparticle composite dispersion liquid according to (1) or (2) above. (4) The organic dispersion medium is one or a mixed dispersion medium of two or more selected from acetone, PGMEA, PGME, IPA, ethanol, and methanol; The semiconductor nanoparticle composite dispersion liquid according to (1) or (2) above. (5) The organic dispersion medium is one or a mixed dispersion medium of two or more selected from the group consisting of glycol ethers and glycol ether esters. The semiconductor nanoparticle composite dispersion liquid according to (1) or (2) above. (6) The organic dispersion medium is one or more mixed dispersion media selected from the group consisting of PGMEA and PGME. The semiconductor nanoparticle composite dispersion liquid according to (1) or (2) above. (7) The semiconductor nanoparticle composite dispersion has a fluorescence quantum efficiency of 80% or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (6) above. (8) The mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) is 0.05 to 1.00. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (7) above. (9) The aliphatic thiol ligand has 6 to 14 carbon atoms. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (8) above. (10) The aliphatic thiol ligand is one or more of hexanethiol, octanethiol, and dodecanethiol. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (9) above. (11) The molecular weight of the polar ligand is 600 or less. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (10) above. (12) The molecular weight of the polar ligand is 450 or less. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (11) above. (13) The organic group of the polar ligand has at least one of a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ether bond, an ester bond, and a siloxane bond. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (12) above. (14) The organic group of the polar ligand has an ether bond. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (13) above. (15) The coordinating group of the polar ligand is a mercapto group or a carboxyl group. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (14) above. (16) The coordinating group of the polar ligand is a mercapto group. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (15) above. (17) The total mass fraction of the aliphatic thiol ligands and the polar ligands in the total surface ligands is 0.7 or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (16) above. (18) The total mass fraction of the aliphatic thiol ligands and the polar ligands in the total surface ligands is 0.8 or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (17) above. (19) The surface composition of the semiconductor nanoparticles contains Zn. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (18) above. (20) The semiconductor nanoparticle composite has a fluorescence quantum efficiency of 80% or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (19) above. (21) The semiconductor nanoparticle composite has a fluorescence quantum efficiency of 85% or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (20) above. (22) The semiconductor nanoparticle composite has an emission spectrum with a half-width of 40 nm or less. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (21) above. (23) The semiconductor nanoparticle composite has an emission spectrum having a half-width of 35 nm or less. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (22) above. (24) The semiconductor nanoparticles contain In and P. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (23) above. (25) The mass fraction of the semiconductor nanoparticles relative to the semiconductor nanoparticle composite dispersion liquid is 20 mass% or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (24) above. (26) The mass fraction of the semiconductor nanoparticles relative to the semiconductor nanoparticle composite dispersion is 25 mass% or more. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (25) above. (27) The organic dispersion medium is a monomer or a prepolymer. The semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (26) above.

[0059] The semiconductor nanoparticle composite composition and semiconductor nanoparticle composite cured film of the present invention can be produced by the following production method. (28) A method for producing a semiconductor nanoparticle composite composition, comprising: Adding either or both of a crosslinking agent and a dispersion medium to the semiconductor nanoparticle composite dispersion liquid according to any one of (1) to (27) above; Method for producing semiconductor nanoparticle composite compositions. (29) A method for producing a semiconductor nanoparticle composite cured film, comprising the steps of: curing the semiconductor nanoparticle composite composition obtained by the method for producing a semiconductor nanoparticle composite composition according to (28) above; Method for producing a semiconductor nanoparticle composite cured film.

[0060] The semiconductor nanoparticle composite of the present invention employs the following configuration. <1> A semiconductor nanoparticle composite in which two or more types of ligands, including an aliphatic thiol ligand and a polar ligand, are coordinated to the surface of a semiconductor nanoparticle, the ligand comprises an organic group and a coordinating group; The aliphatic thiol ligand has an aliphatic hydrocarbon group as the organic group and a mercapto group as the coordinating group, The polar ligand includes a hydrophilic functional group in the organic group, the mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) is 0.05 to 1.00; Semiconductor nanoparticle composites. <2> The semiconductor nanoparticle composite is dispersible in an organic dispersion medium having an SP value of 8.5 or more. the above <1> The semiconductor nanoparticle composite according to claim 1. <3> The semiconductor nanoparticle composite is dispersible in an organic dispersion medium having an SP value of 9.0 or more. the above <1> or <2> The semiconductor nanoparticle composite according to claim 1. <4> The organic dispersion medium is one or a mixed dispersion medium of two or more selected from the group consisting of alcohols, glycol ethers, and glycol ether esters. the above <2> or <3> The semiconductor nanoparticle composite according to claim 1. <5> The organic dispersion medium is one or a mixed dispersion medium of two or more selected from the group consisting of acetone, PGMEA, PGME, IPA, ethanol, and methanol. the above <2> ~ <4> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <6> The aliphatic thiol ligand has 6 to 14 carbon atoms. the above <1> ~ <5> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <7> the aliphatic thiol ligand is one or more of hexanethiol, octanethiol, decanethiol, and dodecanethiol; the above <1> ~ <6> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <8> The molecular weight of the polar ligand is 600 or less. the above <1> ~ <7> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <9> The molecular weight of the polar ligand is 450 or less. the above <1> ~ <8> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <10> the total mass fraction of the aliphatic thiol ligand and the polar ligand in the total mass of the ligands is 0.7 or more; the above <1> ~ <9> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <11> the total mass fraction of the aliphatic thiol ligand and the polar ligand in the total mass of the ligands is 0.8 or more; the above <1> ~ <10> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <12> the organic group of the polar ligand has at least one of a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ether bond, an ester bond, and a siloxane bond; the above <1> ~ <11> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <13> the organic group of the polar ligand comprises an ether bond; the above <1> ~ <12> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <14> the coordinating group of the polar ligand is a mercapto group or a carboxyl group; the above <1> ~ <13> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <15> the coordinating group of the polar ligand is a mercapto group; the above <1> ~ <14> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <16> The semiconductor nanoparticle composite is dispersible in the organic dispersion medium, and the mass fraction of the semiconductor nanoparticles is 20 mass% or more. the above <2> ~ <15> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <17> The semiconductor nanoparticle composite is dispersible in the organic dispersion medium, and the mass fraction of the semiconductor nanoparticles is 25 mass% or more. the above <2> ~ <16> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <18> The semiconductor nanoparticle composite has a fluorescence quantum efficiency of 80% or more. the above <1> ~ <17> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <19> The semiconductor nanoparticle composite has a fluorescence quantum efficiency of 85% or more. the above <1> ~ <18> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <20> The semiconductor nanoparticle composite has an emission spectrum with a half-width of 40 nm or less. the above <1> ~ <19> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <21> The semiconductor nanoparticle composite has an emission spectrum with a half-width of 35 nm or less. the above <1> ~ <20> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <22> the semiconductor nanoparticles comprise In and P; the above <1> ~ <21> The semiconductor nanoparticle composite according to any one of claims 1 to 4. <23> The semiconductor nanoparticles contain Zn on the surface of the semiconductor nanoparticles. the above <1> ~ <22> The semiconductor nanoparticle composite according to any one of claims 1 to 4.

[0061] The semiconductor nanoparticle composite dispersion of the present invention employs the following configuration. <24> the above <1> ~ <23> 10. A semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite according to any one of claims 1 to 9 is dispersed in an organic dispersion medium.

[0062] The semiconductor nanoparticle composite composition of the present invention employs the following configuration. <25> the above <1> ~ <23> A semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite according to any one of the preceding claims is dispersed in a dispersion medium, The dispersion medium is a monomer or a prepolymer. Semiconductor nanoparticle composite compositions.

[0063] The semiconductor nanoparticle composite cured film of the present invention employs the following configuration. <26> the above <1> ~ <23> The semiconductor nanoparticle composite according to any one of the preceding claims is dispersed in a polymer matrix. Semiconductor nanoparticle composite cured film.

[0064] It will be understood that the structures and / or methods described herein are presented by way of example and that numerous variations are possible, and therefore, these specific examples or examples should not be construed in a limiting sense. A particular procedure or method described herein may represent one of numerous processing methods. Thus, various acts illustrated and / or described may be performed in the order illustrated and / or described, or may be omitted. Similarly, the order of the methods described above may be changed. The subject matter of the present disclosure includes all novel and non-obvious combinations and subcombinations of the various methods, systems, and structures, as well as other features, functions, acts, and / or properties disclosed herein, and all equivalents thereof. [Example]

[0065] EXAMPLES The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0066] [Example 1] An InP-based semiconductor nanoparticle composite was prepared according to the following method. (core) Indium acetate (0.3 mmol) and zinc oleate (0.6 mmol) were added to a mixture of oleic acid (0.9 mmol), 1-dodecanethiol (0.1 mmol), and octadecene (10 mL), and the mixture was heated to approximately 120°C under vacuum (<20 Pa) and reacted for 1 hour. The mixture reacted under vacuum was then returned to 25°C under a nitrogen atmosphere, and tris(trimethylsilyl)phosphine (0.2 mmol) was added. The mixture was then heated to approximately 300°C and reacted for 10 minutes. The reaction solution was cooled to 25°C, and octanoic acid chloride (0.45 mmol) was added. The mixture was heated at approximately 250°C for 30 minutes and then cooled to 25°C to obtain a dispersion of InP-based semiconductor nanoparticles. These InP-based semiconductor nanoparticles were used as cores, and a shell was formed on the core surface as follows to produce core-shell semiconductor nanoparticles, and their optical properties were measured.

[0067] (Shell precursor) In the preparation of the shell, first, the following precursors were prepared. <Preparation of Zn precursor solution> 40 mmol of zinc oleate and 75 mL of octadecene were mixed and heated at 110 °C for 1 hour under vacuum to prepare a Zn precursor with [Zn]=0.4 M. <Preparation of Se precursor (trioctylphosphine selenide)> 22 mmol of selenium powder and 10 mL of trioctylphosphine were mixed in nitrogen and stirred until completely dissolved to obtain trioctylphosphine selenide with [Se]=2.2 M. <Preparation of S precursor (trioctylphosphine sulfide)> 22 mmol of sulfur powder and 10 mL of trioctylphosphine were mixed in nitrogen and stirred until completely dissolved to obtain trioctylphosphine sulfide with [S]=2.2 M. Using the precursors obtained as described above, a shell was formed on the surface of the InP-based semiconductor nanoparticles (core) as follows.

[0068] (Shell) The dispersion of the core was heated to 200 °C. At 200 °C, 0.75 mL of the Zn precursor solution and trioctylphosphine selenide (Se precursor) were simultaneously added and reacted for 30 minutes to form a ZnSe shell on the surface of the InP-based semiconductor nanoparticles. Furthermore, 1.5 mL of the Zn precursor solution and 0.6 mmol of trioctylphosphine sulfide (S precursor) were added, the temperature was raised to 250 °C and reacted for 1 hour to form a ZnS shell. The reaction solution of the semiconductor nanoparticles obtained by synthesis was added to acetone, mixed well and then centrifuged. The centrifugal acceleration was 4000 G. The precipitate was collected, and normal hexane was added to the precipitate to prepare a dispersion. This operation was repeated several times to obtain purified semiconductor nanoparticles.

[0069] (Ligand) - Preparation of ligand alone - <Preparation method of PEG-SH> 210 g of methoxy PEG-OH (molecular weight 400) and 93 g of triethylamine were placed in a flask and dissolved in 420 mL of THF (tetrahydrofuran). The solution was cooled to 0 °C, and while taking care that the temperature of the reaction solution did not exceed 5 °C due to the heat of reaction, 51 g of methanesulfonic acid chloride was gradually added dropwise under a nitrogen atmosphere. Then, the reaction solution was warmed to room temperature and stirred for 2 hours. This solution was extracted with a chloroform - water system, and the organic phase was recovered. The obtained solution was dried with magnesium sulfate, and after removing the magnesium sulfate by filtration, the filtrate was concentrated by evaporation to obtain an oily intermediate. This was transferred to another flask, and 400 mL of a 1.3 M aqueous thiourea solution was added under a nitrogen atmosphere. After refluxing the solution for 2 hours, 21 g of NaOH was added, and refluxing was continued for another 1.5 hours. The reaction solution was cooled to room temperature, and 1 M aqueous HCl was added until pH = 7 to neutralize it. The obtained solution was extracted with a chloroform - water system to obtain the target ligand (PEG - SH, molecular weight 400).

[0070] <Method for Preparing N - acetyl N-(2 - mercaptoethyl)propanamide> 1.2 g (10 mmol) of N-(2 - sulfanylethyl)acetamide and 1.7 mL (12 mmol) of triethylamine were placed in a 100 mL round - bottom flask and dissolved in 30 mL of dehydrated dichloromethane. The solution was cooled to 0 °C, and 0.87 mL (10 mmol) of propanoyl chloride was slowly added dropwise under a nitrogen atmosphere while taking care that the temperature of the solution did not exceed 5 °C. After completion of the dropwise addition, the reaction solution was warmed to room temperature and stirred for 2 hours. The reaction solution was filtered, and the filtrate was diluted with chloroform. The solution was extracted successively with 10% aqueous HCl, 10% aqueous Na2CO3, and saturated aqueous NaCl, and the organic phase was recovered. After concentrating the organic phase by evaporation, it was purified by column chromatography using a hexane - ethyl acetate mixed solvent as the developing solvent to obtain the target product.

[0071] <Method for Preparing PEG - COOH> Dissolve methoxy PEG-OH (molecular weight 350, 15 g) in toluene (100 mL) at 60 °C, add 4.2 g of potassium tert-butoxide, and react for 6 hours. Then, add 5.5 g of ethyl bromoacetate to the mixture, and the hydroxyl groups in PEG were protected by ethyl acetate groups. The mixture was filtered, and the filtrate was precipitated in diethyl ether. The precipitate was dissolved in 1 M NaOH solution (40 mL), add NaCl (10 g), and stir at room temperature for 1 hour to remove the terminal ethyl groups of PEG. This solution was adjusted to pH 3.0 by adding 6 M HCl. The resulting solution was extracted with chloroform-aqueous system to obtain PEG-COOH with a molecular weight of 400.

[0072] By changing methoxy PEG-OH (molecular weight 350, 15 g) to methoxy PEG-OH (molecular weight 550, 21 g) and performing the preparation in the same manner as above, PEG-COOH with a molecular weight of 600 was obtained. By changing methoxy PEG-OH (molecular weight 350, 15 g) to methoxy PEG-OH (molecular weight 700, 26 g) and performing the preparation in the same manner as above, PEG-COOH with a molecular weight of 700 was obtained. By changing methoxy PEG-OH (molecular weight 350, 15 g) to methoxy PEG-OH (molecular weight 950, 36 g) and performing the preparation in the same manner as above, PEG-COOH with a molecular weight of 1000 was obtained.

[0073] <Preparation method of TBP-S> Place 3.2 g of sulfur in a flask under a nitrogen atmosphere, add 25 mL of tributylphosphine, and stir overnight to obtain TBP-S.

[0074] <Preparation method of TOP-S> Place 3.2 g of sulfur in a flask under a nitrogen atmosphere, add 50 mL of trioctylphosphine, and stir overnight to obtain TOP-S.

[0075] (Preparation of semiconductor nanoparticle composites) A semiconductor nanoparticle 1-octadecene dispersion was prepared by dispersing purified semiconductor nanoparticles in 1-octadecene at a mass ratio of 10% by mass in a flask. 10.0 g of the prepared semiconductor nanoparticle 1-octadecene dispersion was placed in a flask, and 0.2 g of dodecanethiol (DDT) as an aliphatic thiol ligand and 4 g of PEG-SH as a polar ligand were added. The mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and then cooled to 25°C to obtain a semiconductor nanoparticle composite. The reaction solution containing the semiconductor nanoparticle composite was transferred to a centrifuge tube and centrifuged at 4000 G for 20 minutes, resulting in separation into a transparent 1-octadecene phase and a semiconductor nanoparticle composite phase. The 1-octadecene phase was removed, and the remaining semiconductor nanoparticle composite phase was recovered. 5.0 mL of acetone was added to the obtained semiconductor nanoparticle composite phase to prepare a dispersion. 50 mL of normal hexane was added to the obtained dispersion, and the mixture was centrifuged at 4000 G for 20 minutes. After centrifugation, the clear supernatant was removed and the precipitate was collected. This procedure was repeated several times to obtain a purified semiconductor nanoparticle composite.

[0076] (Optical property measurement of semiconductor nanoparticle composites) The optical properties of the semiconductor nanoparticle composite were measured using a fluorescence quantum efficiency measurement system (Otsuka Electronics, QE-2100). The obtained semiconductor nanoparticle composite was dispersed in a dispersion medium and exposed to a single light of 450 nm to obtain an emission spectrum. The fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) were calculated from the reexcitation-corrected emission spectrum obtained by subtracting the reexcitation fluorescence emission spectrum, which corresponds to the amount of fluorescence emitted by reexcitation. PGMEA was used as the dispersion medium.

[0077] (Dispersibility test of semiconductor nanoparticle composites) The purified semiconductor nanoparticle composite was heated to 550°C by differential thermogravimetry (DTA-TG), held at that temperature for 10 minutes, and then cooled. The residual mass after analysis was taken as the mass of the semiconductor nanoparticles, and the mass ratio of the semiconductor nanoparticles to the semiconductor nanoparticle composite was determined from this value. With reference to the above mass ratio, an organic dispersion medium was added to the semiconductor nanoparticle composite so that the mass fraction of the semiconductor nanoparticles was 20 mass%, and the dispersion state at that time was confirmed. Those that were dispersed were marked with an O, and those in which precipitation or turbidity was observed were marked with an X, as shown in Tables 1-1 to 1-7. Table 2 shows the dispersion state when PGMEA was used as the organic dispersion medium and the mass fraction of the semiconductor nanoparticles was set to 20% by mass to 35% by mass. ◯ indicates that the dispersion was achieved, and × indicates that precipitation or turbidity was observed. When two types of organic dispersion media were used as the dispersion media, a mixed dispersion media mixed at a volume ratio of 1:1 was used.

[0078] The ligands coordinated to the semiconductor nanoparticles of the purified semiconductor nanoparticle composites were measured using a nuclear magnetic resonance (NMR) spectrometer (JNM-LA400 manufactured by JEOL Ltd.) Deuterated chloroform was used as the solvent in all measurements, and tetramethylsilane was used as the internal standard for chemical shifts. Figure 1 shows the results of 1H-NMR measurement of the semiconductor nanoparticle composite prepared in Example 1. Signals were observed around 0.8 ppm to 2.5 ppm, 3.5 ppm to 4.0 ppm, and around 5.4 ppm. Figure 2 shows the 1H-NMR spectra of dodecanethiol, oleic acid, and PEG-SH. 1 and 2, it was found that the signals around 0.8 ppm to 2.5 ppm and around 5.4 ppm are attributable to the alkyl group and carbon-carbon double bond of the aliphatic thiol ligand, respectively, and the signal around 3.5 ppm to 4.0 ppm is attributable to the ether bond of the polar ligand. In other words, by adding up the signals of dodecanethiol, oleic acid, and PEG-SH, all of the signals obtained in the NMR spectrum of Example 1 can be consistently explained, which indicates that the semiconductor nanoparticle composite of Example 1 contains dodecanethiol, oleic acid, and PEG-SH as ligands. Furthermore, a comparison of Figures 1 and 2 reveals that the signals around 0.8 ppm to 2.5 ppm belong to dodecanethiol and oleic acid, the signals around 3.5 ppm to 4.0 ppm belong to PEG-SH, and the signal around 5.4 ppm belongs to oleic acid. From the area ratio of these signals, the abundance ratio of each ligand was calculated to be dodecanethiol:oleic acid:PEG-SH = 8:3:89. Thus, the type and abundance ratio of the ligands can be determined from the position and peak area of ​​each signal in the 1H-NMR spectrum.

[0079] Example 2 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of dodecanethiol was used as the aliphatic thiol ligand and 4.0 g of PEG-SH was used as the polar ligand in the step of preparing the semiconductor nanoparticle composite.

[0080] Example 3 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 1.0 g of dodecanethiol was used as the aliphatic thiol ligand, 1.5 g of PEG-SH was used as the polar ligand, and 0.5 g of oleic acid was further added.

[0081] Example 4 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 1.0 g of dodecanethiol was used as the aliphatic thiol ligand, 1.5 g of N-acetyl-N-(2-mercaptoethyl)propanamide was used as the polar ligand, and 0.5 g of oleic acid was further added.

[0082] Example 5 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 0.3 g of dodecanethiol and 0.2 g of hexanethiol were used as aliphatic thiol ligands, and 4.0 g of PEG-SH was used as a polar ligand.

[0083] Example 6 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 0.2 g of dodecanethiol was used as the aliphatic thiol ligand, 1.5 g of triethylene glycol monomethyl thiol (TEG-SH) was used as the polar ligand, and 0.5 g of oleic acid was further added.

[0084] Example 7 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of octanethiol was used as the aliphatic thiol ligand and 4.0 g of N-acetyl-N-(2-mercaptoethyl)propanamide was used as the polar ligand in the process of preparing the semiconductor nanoparticle composite.

[0085] Example 8 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of hexanethiol was used as the aliphatic thiol ligand and 4.0 g of N-acetyl-N-(2-mercaptoethyl)propanamide was used as the polar ligand in the process of preparing the semiconductor nanoparticle composite.

[0086] Example 9 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of hexanethiol was used as the aliphatic thiol ligand and 4.0 g of PEG-SH was used as the polar ligand in the step of preparing the semiconductor nanoparticle composite.

[0087] Example 10 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 1.0 g of decanethiol was used as the aliphatic thiol ligand and 4.0 g of N-acetyl-N-(2-mercaptoethyl)propanamide was used as the polar ligand.

[0088] Example 11 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.2 g of dodecanethiol was used as the aliphatic thiol ligand and 6.0 g of PEG-COOH (molecular weight 400) was used as the polar ligand in the step of preparing the semiconductor nanoparticle composite.

[0089] Example 12 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 0.5 g of dodecanethiol was used as the aliphatic thiol ligand, 2.0 g of methyl 3-mercaptopropionate was used as the polar ligand, and 0.5 g of oleic acid was further added.

[0090] Example 13 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of dodecanethiol was used as the aliphatic thiol ligand and 6.0 g of PEG-COOH (molecular weight 600) was used as the polar ligand in the process of preparing the semiconductor nanoparticle composite.

[0091] Example 14 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.5 g of dodecanethiol was used as the aliphatic thiol ligand and 7.5 g of PEG-COOH (molecular weight 750) was used as the polar ligand in the step of preparing the semiconductor nanoparticle composite.

[0092] Example 15 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 0.5 g of dodecanethiol was used as the aliphatic thiol ligand and 10.0 g of PEG-COOH (molecular weight 1000) was used as the polar ligand.

[0093] Example 16 A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, 0.5 g of dodecanethiol was used as the aliphatic thiol ligand, 4.0 g of PEG-SH was used as the polar ligand, and 1.5 g of oleic acid was further added.

[0094] (Comparative Example 1) A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, no aliphatic thiol ligand was added, 4.0 g of PEG-SH was used as the polar ligand, and 4.0 g of tributylphosphine (TBP) was also added.

[0095] (Comparative Example 2) A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the process of preparing the semiconductor nanoparticle composite, no aliphatic thiol ligand was added, 4.0 g of PEG-SH was used as the polar ligand, and 4.0 g of trioctylphosphine (TOP) was also added.

[0096] (Comparative Example 3) A flask was charged with 1.0 g of semiconductor nanoparticle composite purified in the same manner as in Example 1, 10 mL of isopropanol, and 4.0 g of PEG-SH. This solution was stirred at 80°C for 180 minutes under a nitrogen atmosphere and then cooled to 25°C. 50 mL of normal hexane was added to the reaction solution, and the mixture was centrifuged at 4000G for 20 minutes. After centrifugation, the clear supernatant was removed and the precipitate was collected. 5.0 mL of acetone was added to the precipitate to prepare a dispersion. 50 mL of normal hexane was added to the resulting dispersion, and the mixture was centrifuged at 4000G for 20 minutes. After centrifugation, the clear supernatant was removed and the precipitate was collected. This procedure was repeated several times to obtain a purified semiconductor nanoparticle composite.

[0097] Comparative Example 4 In the process of preparing the semiconductor nanoparticle composite, 2.0 g of dodecanethiol was used as the aliphatic thiol ligand, 1.0 g of N-acetyl-N-(2-mercaptoethyl)propanamide was used as the polar ligand, and 1.0 g of oleic acid was added. The mixture was then stirred at 110°C for 60 minutes under a nitrogen atmosphere and cooled to 25°C. 5.0 mL of normal hexane was added to the reaction solution to prepare a dispersion. 50 mL of acetone was added to the resulting dispersion, and the mixture was centrifuged at 4000G for 20 minutes. After centrifugation, the clear supernatant was removed and the precipitate was collected. This procedure was repeated several times to obtain a purified semiconductor nanoparticle composite. Since the semiconductor nanoparticle composite of Comparative Example 4 did not disperse in PGMEA, the optical properties were measured after dispersing it in normal hexane.

[0098] (Comparative Example 5) A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that no aliphatic thiol was added in the process of preparing the semiconductor nanoparticle composite, and further, 4.0 g of PEG-SH was used as the polar ligand in the process of preparing the semiconductor nanoparticle composite, and 1.0 g of oleic acid was added.

[0099] The luminescence properties of the obtained semiconductor nanoparticle composites, the ligand mass ratio, and the state of dispersion in the dispersion medium are shown in Tables 1-1 to 1-7.

[0100] The meanings of the abbreviations shown in Tables 1-1 to 1-7 are as follows: QY: Fluorescence quantum efficiency FWHM: Half width of the emission spectrum QD: Semiconductor nanoparticles (quantum dots) DDT: Dodecanethiol Hex-SH: hexanethiol Oct-SH: Octanethiol Dec-SH: Decanethiol OA: Oleic acid

[0101] [Table 1-1]

[0102] [Table 1-2]

[0103] [Table 1-3]

[0104] [Table 1-4]

[0105] Table 1-5

[0106] Table 1-6

[0107] Table 1-7

[0108] Table 2

Claims

1. A semiconductor nanoparticle composite in which two or more types of ligands, including an aliphatic thiol ligand and a polar ligand, are coordinated to the surface of a semiconductor nanoparticle, the ligand comprises an organic group and a coordinating group; The aliphatic thiol ligand has an aliphatic hydrocarbon group as the organic group and a mercapto group as the coordinating group, The polar ligand includes a hydrophilic functional group in the organic group, the hydrophilic functional group includes at least one of a hydroxyl group, a carboxyl group, a carbonyl group, an amino group, an ether bond, an ester bond, and a siloxane bond; the mass ratio of the aliphatic thiol ligand to the polar ligand (aliphatic thiol ligand / polar ligand) is 0.05 to 1.00; the total mass fraction of the aliphatic thiol ligand and the polar ligand in the total mass of the ligands is 0.7 or more; Semiconductor nanoparticle composites.

2. the aliphatic thiol ligand has 6 to 14 carbon atoms; The semiconductor nanoparticle composite of claim 1 .

3. The molecular weight of the polar ligand is 600 or less. The semiconductor nanoparticle composite according to claim 1 or 2.

4. the organic group of the polar ligand comprises an ether bond; The semiconductor nanoparticle composite according to any one of claims 1 to 3.

5. the coordinating group of the polar ligand is a mercapto group; The semiconductor nanoparticle composite according to any one of claims 1 to 4.

6. The semiconductor nanoparticle composite has a fluorescence quantum efficiency of 80% or more. The semiconductor nanoparticle composite according to any one of claims 1 to 5.

7. The semiconductor nanoparticle composite has an emission spectrum with a half-width of 40 nm or less. The semiconductor nanoparticle composite according to any one of claims 1 to 6.

8. the semiconductor nanoparticles comprise In and P; The semiconductor nanoparticle composite according to any one of claims 1 to 7.

9. A semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite according to any one of claims 1 to 8 is dispersed in an organic dispersion medium.

10. A semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite according to any one of claims 1 to 8 is dispersed in a dispersion medium, The dispersion medium is a monomer or a prepolymer. Semiconductor nanoparticle composite compositions.

11. The semiconductor nanoparticle composite according to any one of claims 1 to 8 is dispersed in a polymer matrix. Semiconductor nanoparticle composite cured film.

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