Semiconductor nanoparticle composite, semiconductor nanoparticle composite dispersion, semiconductor nanoparticle composite composition, semiconductor nanoparticle composite cured film, and method for purifying semiconductor nanoparticle composite

Abstract

To provide a semiconductor nanoparticle complex that maintains high fluorescence quantum efficiency (QY) before and after purification.SOLUTION: Provided is a semiconductor nanoparticle complex in which a ligand is coordinated to the surface of a semiconductor nanoparticle. The semiconductor nanoparticle includes In and P. The ligand contains a mercapto fatty acid ester represented by the following general formula (1). The SP value of the mercapto fatty acid ester is 9.30 or less. General formula (1): HS-R1-COOR2 (1) (in general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms, and R2 is a hydrocarbon group having 1 to 30 carbon atoms.)SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to semiconductor nanoparticle composites. [Background technology]

[0002] Semiconductor nanoparticles (quantum dots, QDs) are small enough to exhibit the quantum confinement effect, and have a band gap that depends on their particle size. Excitons formed within semiconductor nanoparticles by photoexcitation, charge injection, or other means 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 the 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 are being used in a variety of applications, including displays, biolabeling, and solar cells. For display applications, promising applications include QD films, QD patterning, and self-luminous devices (QLEDs). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] US Patent Application Publication No. 2008 / 0308130 [Patent Document 2] Japanese Patent Application Laid-Open No. 2002-121549 Summary of the Invention [Problem to be solved by the invention]

[0006] Semiconductor nanoparticles and semiconductor nanoparticle composites are prepared as dispersions by dispersing them in a dispersion medium and applied in various fields. In particular, for applications in the display field, such as QD films, QD patterning, and self-luminous devices (QLEDs), nonpolar semiconductor nanoparticles are most commonly prepared using hexane or octane as a good solvent (a dispersion medium with high solubility) and acetone or ethanol as a poor solvent (a dispersion medium with low solubility). As noted in Patent Document 1, such nonpolar semiconductor nanoparticles are purified by repeatedly dispersing them in a good solvent after synthesis and then precipitating them in a poor solvent. In the purification process of nonpolar semiconductor nanoparticles, the poor solvent for nonpolar semiconductor nanoparticles is a polar solvent, which presents a problem of a tendency for the fluorescence quantum efficiency to decrease due to the influence of moisture, etc.

[0007] Semiconductor nanoparticles include II-VI semiconductor nanoparticles, known as CdSe-based nanoparticles, and III-V semiconductor nanoparticles, known as InP-based nanoparticles. To achieve high fluorescence quantum efficiency, these semiconductor nanoparticles often have a core-shell structure, where a shell is formed on the surface of the core nanoparticle, as described above. Because of the quantum confinement effect, II-VI semiconductors such as ZnSe and ZnS are typically used for the shell. Therefore, when the core is a II-VI core particle, the valence of the elements forming the core particle and the shell is the same, facilitating epitaxial growth and enabling uniform shell formation. On the other hand, when the core is a III-V core particle, the valence of the elements forming the core particle and the shell is different, making it difficult to form a uniform shell. This also affects the refining resistance of semiconductor nanoparticles. As mentioned above, while research on non-Cd-based semiconductor nanoparticles has been conducted in recent years, III-V / II-VI core / shell semiconductor nanoparticles have been found to be less refining-resistant than II-VI / II-VI core / shell semiconductor nanoparticles, resulting in a decrease in fluorescence quantum efficiency after refining.

[0008] Furthermore, when forming a cured film such as a QD film or QD patterning, any curing method can be used to cure the dispersion, but when the curing method is thermal curing, heat is applied to the dispersion of the semiconductor nanoparticle composite, so the semiconductor nanoparticles and semiconductor nanoparticle composite must be heat resistant. Therefore, the semiconductor nanoparticle composite may be required to have high heat resistance in addition to resistance to purification.

[0009] Therefore, in order to solve the above problems, a first object of the present invention is to provide a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents and maintains a high fluorescence quantum efficiency (QY) before and after purification. Another object of the present invention is to provide a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents, maintains a high fluorescence quantum efficiency (QY) before and after purification, and also has high dispersibility in nonpolar organic solvents. Another object of the present invention is to provide a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents, maintains a high fluorescence quantum efficiency (QY) before and after purification, and also has high heat resistance. Another object of the present invention is to provide a semiconductor nanoparticle composite that maintains a high fluorescence quantum efficiency (QY) before and after purification, has high dispersibility in nonpolar organic solvents, and has high heat resistance. [Means for solving the problem]

[0010] That is, the present invention (1) provides a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle contains In and P, the ligand contains a mercapto fatty acid ester represented by the following general formula (1), and the SP value of the mercapto fatty acid ester is 9.30 or less.

[0011] General formula (1): HS-R1-COOR2(1) (In general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms, and R2 is a hydrocarbon group having 1 to 30 carbon atoms.)

[0012] The present invention (2) also provides the semiconductor nanoparticle composite of (1), characterized in that in the general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 1 to 20 carbon atoms, the SP value of the mercapto fatty acid ester represented by the general formula (1) is 9.30 or less, and the content of the mercapto fatty acid ester represented by the general formula (1) in the entire ligand is 40.0 mol % or more.

[0013] The present invention (3) also provides a semiconductor nanoparticle composite (2) characterized in that in the general formula (1), R1 is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 1 to 20 carbon atoms.

[0014] The present invention (4) also provides the semiconductor nanoparticle composite of (2) or (3), characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 400 or less.

[0015] The present invention (5) also provides the semiconductor nanoparticle composite of (2) or (3), characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 or less.

[0016] The present invention (6) also provides a semiconductor nanoparticle composite according to any one of (2) to (5), characterized in that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 0.50 or less.

[0017] The present invention (7) also provides a semiconductor nanoparticle composite according to any one of (2) to (6), characterized in that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 0.40 or less.

[0018] The present invention (8) also provides the semiconductor nanoparticle composite of (1), characterized in that in the general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 14 to 30 carbon atoms, and the SP value of the mercapto fatty acid ester represented by the general formula (1) is 9.00 or less.

[0019] The present invention (9) also provides a semiconductor nanoparticle composite according to (8), characterized in that, in a heat resistance test at 180°C for 5 hours in the atmosphere, the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after the heat resistance test relative to the fluorescence quantum efficiency before the heat resistance test ((1-(fluorescence quantum efficiency after heat resistance test / fluorescence quantum efficiency before heat resistance test)) x 100) is less than 10%.

[0020] The present invention (10) also provides a semiconductor nanoparticle composite according to (8) or (9), characterized in that the content of the mercapto fatty acid ester represented by the general formula (1) in the entire ligand is 40.0 mol % or more.

[0021] The present invention (11) also provides a semiconductor nanoparticle composite according to any one of (8) to (10), characterized in that in the general formula (1), R1 is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 14 to 30 carbon atoms.

[0022] The present invention (12) also provides the semiconductor nanoparticle composite of any one of (8) to (11), characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 to 450.

[0023] The present invention (13) also provides the semiconductor nanoparticle composite of any one of (1) to (12), characterized in that the semiconductor nanoparticles are core / shell type semiconductor nanoparticles having a core mainly composed of In and P and one or more shell layers.

[0024] The present invention (14) also provides the semiconductor nanoparticle composite of (13), wherein at least one of the shells is formed of ZnSe.

[0025] The present invention (15) also provides the semiconductor nanoparticle composite according to (13) or (14), characterized in that the shell has two or more layers, and the outermost layer of the shell is formed of ZnS.

[0026] The present invention (16) also provides the semiconductor nanoparticle composite of any one of (13) to (15), characterized in that the shell comprises at least a first shell formed of ZnSe and covering the outer surface of the core, and a second shell formed of ZnS and covering the outer surface of the first shell.

[0027] The present invention (17) also provides the semiconductor nanoparticle composite of any one of (1) to (16), wherein the average SP value of the ligands coordinated to the semiconductor nanoparticles is 9.3 or less.

[0028] The present invention (18) also provides the semiconductor nanoparticle conjugate according to any one of (1) to (17), wherein the ligand further comprises an aliphatic ligand.

[0029] The present invention (19) also provides the semiconductor nanoparticle composite of (18), characterized in that the aliphatic ligand is one or more members selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines.

[0030] The present invention (20) also provides a semiconductor nanoparticle composite according to any one of (1) to (19), characterized in that the content of the mercapto fatty acid ester represented by the general formula (1) in the ligand is 50.0 mol % or more.

[0031] The present invention (21) also provides a semiconductor nanoparticle composite according to any one of (1) to (20), characterized in that the content of the mercapto fatty acid ester represented by the general formula (1) in the ligand is 60.0 mol % or more.

[0032] The present invention (22) also provides a semiconductor nanoparticle composite according to any one of (1) to (21), characterized in that the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification relative to the fluorescence quantum efficiency before purification ((1-(fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification))×100) is less than 20%.

[0033] The present invention (23) also provides a semiconductor nanoparticle composite according to any one of (1) to (22), characterized in that the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification relative to the fluorescence quantum efficiency before purification ((1-(fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification))×100) is less than 10%.

[0034] The present invention (24) also provides the semiconductor nanoparticle composite of any one of (1) to (23), wherein the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification is 80% or more.

[0035] The present invention (25) also provides the semiconductor nanoparticle composite of any one of (1) to (24), wherein the half width of the emission spectrum of the semiconductor nanoparticle composite is 38 nm or less.

[0036] The present invention (26) also provides a purification method comprising agglomerating a semiconductor nanoparticle composite of any one of (1) to (25) using a poor solvent, and then separating the semiconductor nanoparticle composite.

[0037] The present invention (27) also provides a semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite of any one of (1) to (25) is dispersed in an organic dispersion medium.

[0038] The present invention (28) is a semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite of any one of (1) to (25) is dispersed in a dispersion medium, The present invention provides a semiconductor nanoparticle composite composition, wherein the dispersion medium is a monomer or a prepolymer.

[0039] The present invention (29) also provides a semiconductor nanoparticle composite cured film in which the semiconductor nanoparticle composite of any one of (1) to (25) is dispersed in a polymer matrix.

[0040] 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]

[0041] According to the present invention, it is possible to provide a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents and maintains a high fluorescence quantum efficiency (QY) before and after purification. The present invention also provides a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents, maintains a high fluorescence quantum efficiency (QY) before and after purification, and is highly dispersible in nonpolar organic solvents. The present invention also provides a semiconductor nanoparticle composite that is dispersible in nonpolar organic solvents, maintains a high fluorescence quantum efficiency (QY) before and after purification, and is highly heat-resistant. The present invention also provides a semiconductor nanoparticle composite that maintains a high fluorescence quantum efficiency (QY) before and after purification, is highly dispersible in nonpolar organic solvents, and is highly heat-resistant. DETAILED DESCRIPTION OF THE INVENTION

[0042] (Semiconductor nanoparticle composite) The present invention relates to a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle. In the present invention, the semiconductor nanoparticle composite is a semiconductor nanoparticle composite having luminescence properties. The semiconductor nanoparticle composite of the present invention is a particle that absorbs light in the range of 340 nm to 480 nm and emits light with an emission peak wavelength of 400 nm to 750 nm.

[0043] The semiconductor nanoparticle composite of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, the semiconductor nanoparticle containing In and P, and the ligand being represented by the following general formula (1): HS-R1-COOR2(1) (In general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms, and R2 is a hydrocarbon group having 1 to 30 carbon atoms.) The semiconductor nanoparticle composite comprises a mercapto fatty acid ester represented by general formula (1) below, wherein the SP value of the mercapto fatty acid ester represented by general formula (1) is 9.30 or less.

[0044] The semiconductor nanoparticle composite of the present invention comprises semiconductor nanoparticles and ligands coordinated to the surfaces of the semiconductor nanoparticles.

[0045] The semiconductor nanoparticle composite of the present invention can maintain high fluorescence quantum efficiency before and after purification. That is, the semiconductor nanoparticle composite of the present invention has high fluorescence quantum efficiency before purification and also has high fluorescence quantum efficiency after purification, and the rate of change in fluorescence quantum efficiency before and after purification is small.

[0046] The full width at half maximum (FWHM) of the emission spectrum of the semiconductor nanoparticle composite of the present invention is preferably 38 nm or less, and more preferably 35 nm or less, both before and after purification. In particular, when the full width at half maximum of the emission spectrum of the semiconductor nanoparticle composite of the present invention after purification is in the above range, color mixing can be reduced when the semiconductor nanoparticle composite is used in displays and the like.

[0047] The fluorescence quantum efficiency (QY) of the semiconductor nanoparticle composite of the present invention is preferably 80% or higher, and more preferably 85% or higher, both before and after purification. In particular, if the fluorescence quantum efficiency of the semiconductor nanoparticle composite of the present invention after purification is 80% or higher, more efficient color conversion can be achieved when the semiconductor nanoparticle composite is used in applications. In the present invention, the fluorescence quantum efficiency of the semiconductor nanoparticle composite can be measured using a quantum efficiency measurement system.

[0048] In the present invention, the optical properties of semiconductor nanoparticle composites can be measured using a quantum efficiency measurement system. The semiconductor nanoparticle composites are dispersed in a dispersion liquid, and excitation light is applied to obtain an emission spectrum. The fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) are calculated from the reexcitation-corrected emission spectrum obtained by removing the reexcitation fluorescence emission spectrum of the fluorescent light emitted by reexcitation from the obtained emission spectrum. Examples of dispersion liquids include normal hexane.

[0049] -Semiconductor nanoparticles- The semiconductor nanoparticles constituting the semiconductor nanoparticle composite of the present invention, i.e., the particles to which the ligands are coordinated, contain a group III element and a group V element. In particular, from the viewpoints of luminescence properties and safety, it is preferable that the semiconductor nanoparticles contain In and P.

[0050] From the viewpoint of quantum confinement effect, the semiconductor nanoparticles are preferably core / shell semiconductor nanoparticles having a semiconductor nanoparticle containing In and P as a core particle and one or more shell layers. Core / shell semiconductor nanoparticles more preferably have two or more shell layers. The shell preferably includes a shell having a composition containing Zn and Se, and at least one of the shells is preferably formed of ZnSe. When the core / shell semiconductor nanoparticles have two or more shell layers, the outermost shell is preferably a shell having a composition containing Zn and S, and more preferably formed of ZnS. In particular, when the shells are at least a first shell formed of ZnSe and covering the outer surface of the core particle, and a second shell formed of ZnS and covering the outer surface of the first shell, the fluorescence quantum efficiency can be increased.

[0051] As long as the effects of the present invention are not impaired, the composition in the shell does not necessarily have to be a stoichiometric composition, and each shell may contain elements other than Zn, Se, and S, or the shell may have one or more gradient shells in which the ratio of the elements constituting the shell changes within the shell.

[0052] 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.

[0053] An example of a method for producing semiconductor nanoparticles will be disclosed below. The core of the semiconductor nanoparticles can be formed by mixing an In precursor, a P precursor, and, if necessary, an additive in a solvent and heating the resulting precursor mixture.

[0054] Coordinating and non-coordinating solvents are used, including 1-octadecene, hexadecane, squalane, oleylamine, trioctylphosphine, and trioctylphosphine oxide.

[0055] Examples of precursors of In include, but are not limited to, acetates, carboxylates, and halides containing In.

[0056] Examples of precursors of P include, but are not limited to, organic compounds and gases containing P. When the precursor is a gas, the core can be formed by injecting the gas into a precursor mixture containing other gases and allowing the gas to react with the precursor.

[0057] The semiconductor nanoparticles may contain one or more elements other than In and P, as long as the effects of the present invention are not impaired. In this case, precursors of the elements may be added during core formation.

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] -Ligand- The semiconductor nanoparticle composite of the present invention 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 the semiconductor nanoparticle has a ligand on at least a portion of its surface, the ligand may not necessarily be bonded.

[0071] In the semiconductor nanoparticle composite of the present invention, the ligand coordinated to the semiconductor nanoparticle contains a mercapto fatty acid ester represented by the following general formula (1).

[0072] General formula (1): HS-R1-COOR2(1)

[0073] In general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms, and R2 is a hydrocarbon group having 1 to 30 carbon atoms. 1 is not particularly limited, and examples thereof include an alkylene group. The alkylene group may have a branched structure. Furthermore, in general formula (1), R2 is not particularly limited, and examples thereof include a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group having 14 to 30 carbon atoms, and a hydrocarbon group having 14 to 20 carbon atoms, and more specifically, an alkyl group, an alkenyl group, and an alkynyl group. The alkyl group, alkenyl group, and alkynyl group may have a branched structure. When R1 and R2 in general formula (1) are as described above, the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification is reduced. The mercapto fatty acid ester represented by general formula (1) may be one type alone or two or more types in combination.

[0074] As disclosed in Patent Document 2, mercapto fatty acid esters are used as ligands that enable semiconductor nanoparticles to be dispersed in polar solvents. However, in the present invention, the inventors have found that by coordinating a mercapto fatty acid ester represented by general formula (1) to semiconductor nanoparticles, the dispersibility in non-polar solvents can be maintained, the initial fluorescence quantum efficiency is high, and the rate of change in fluorescence quantum efficiency after purification compared to before purification can be reduced.

[0075] Furthermore, in the semiconductor nanoparticle composite of the present invention, the SP value of the mercapto fatty acid ester represented by general formula (1) is 9.30 or less. When the SP value of the mercapto fatty acid ester is 9.30 or less, it becomes possible to disperse the semiconductor nanoparticles in a nonpolar solvent at a high mass fraction.

[0076] Here, the SP value of the ligand can be determined by calculation using the Y-MB method.

[0077] In the semiconductor nanoparticle composite of the present invention, the mercapto fatty acid ester represented by general formula (1) preferably has R1 as an alkylene group having 1 to 11 carbon atoms and R2 as an alkyl group having 1 to 30 carbon atoms, in terms of excellent dispersibility in non-polar solvents.

[0078] In the semiconductor nanoparticle composite of the present invention, the molecular weight of the mercapto fatty acid ester represented by general formula (1) is preferably 450 or less.

[0079] In the semiconductor nanoparticle composite of the present invention, the content of the mercapto fatty acid ester represented by general formula (1) in the total ligands is preferably 40.0 mol% or more, more preferably 50.0 mol% or more, and even more preferably 60 mol% or more. By setting the content of the mercapto fatty acid ester in the total ligands within this range, the effect of reducing the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification is enhanced.

[0080] In the semiconductor nanoparticle composite of the present invention, the average SP value of the ligands coordinated to the semiconductor nanoparticles is preferably 9.30 or less. The SP value of the ligand can be calculated from the structural formula using the Y-MB method.

[0081] When multiple types of ligands are coordinated to a semiconductor nanoparticle, the SP value of each ligand is multiplied by the volume fraction of the ligand, and the average SP value of all the ligands obtained by adding them together is taken as the SP value of the ligand. For example, if a semiconductor nanoparticle is coordinated with P1 volume % of ligands with SP value A1, P2 volume % of ligands with SP value A2, etc., the average SP value of all the ligands is expressed by the following formula (2): Average SP value of all ligands = Σ(Ai × Pi / 100) (2)

[0082] In the semiconductor nanoparticle composite of the present invention, the ligand preferably further comprises an aliphatic ligand. The inclusion of an aliphatic ligand enhances dispersibility in a non-polar dispersion medium. Examples of the aliphatic ligand include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, and aliphatic amines. However, in terms of the strength of the coordination force with the semiconductor nanoparticles, it is particularly preferable to use one or more ligands selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines.

[0083] By virtue of having the above-described structure, the semiconductor nanoparticle composite of the present invention has dispersibility in non-polar organic solvents and can maintain a high fluorescence quantum efficiency (QY) before and after purification.

[0084] In the semiconductor nanoparticle composite of the first embodiment of the present invention, in the general formula (1), R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 1 to 20 carbon atoms, the SP value of the mercapto fatty acid ester represented by the general formula (1) is 9.30 or less, and the content of the mercapto fatty acid ester represented by the general formula (1) in the entire ligand is 40.0 mol% or more. That is, the semiconductor nanoparticle composite of the first embodiment of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle contains In and P, and the ligand contains a mercapto fatty acid ester represented by general formula (1) in which R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 1 to 20 carbon atoms (hereinafter also referred to as mercapto fatty acid ester (1A)), the SP value of the mercapto fatty acid ester (1A) is 9.30 or less, and the content of the mercapto fatty acid ester (1A) in the entire ligand is 40.0 mol % or more.

[0085] The semiconductor nanoparticle composite of the first embodiment of the present invention has improved dispersibility in non-polar organic solvents by containing, as a ligand, a mercapto fatty acid ester (1A) in which R1 in general formula (1) is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 1 to 20 carbon atoms. In particular, the mercapto fatty acid ester (1A) in which R1 is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 1 to 20 carbon atoms facilitates dispersion of the semiconductor nanoparticle composite in non-polar solvents.

[0086] R1 in the mercapto fatty acid ester (1A) has 1 to 11 carbon atoms, preferably 2 to 6, and is not particularly limited as long as it has 1 to 11 carbon atoms, and examples of linear groups include an ethylene group, a propylene group, and a hexyl group, while examples of branched groups include a 1,2-propylene group. R2 in the mercapto fatty acid ester (1A) has 1 to 20 carbon atoms, and is not particularly limited as long as it has 1 to 20 carbon atoms, and examples of linear groups include a methyl group, a hexyl group, an octyl group, a stearyl group, a palmityl group, and an eicosal group, while examples of branched groups include an ethylhexyl group, a 2-n-octyldodecyl group, etc. The mercapto fatty acid ester (1A) is not particularly limited as long as both R1 and R2 satisfy the above-mentioned number of carbon atoms, and examples thereof include isooctyl thioglycolate, tridecyl 3-mercaptopropionate, ethylhexyl 6-mercaptohexanoate, and methyl 11-mercaptoundecanoate.

[0087] In particular, in the semiconductor nanoparticle composite of the first embodiment of the present invention, the mercapto fatty acid ester (1A) is a mercapto fatty acid ester in which R2 in general formula (1) has 14 to 20 carbon atoms, which not only improves the dispersibility of the semiconductor nanoparticle composite in non-polar solvents but also increases the heat resistance of the semiconductor nanoparticle composite.

[0088] The SP value of the mercapto fatty acid ester (1A) is 9.30 or less, preferably 7.00 to 9.20. When the SP value of the mercapto fatty acid ester (1A) is within the above range, the dispersibility of the semiconductor nanoparticle composite in a non-polar organic solvent is improved.

[0089] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the content of the mercapto fatty acid ester (1A) in the entire ligands is 40.0 mol % or more, preferably 50.0 mol % or more, and more preferably 60.0 mol % or more. By setting the content of the mercapto fatty acid ester (1A) in the entire ligands within this range, it is possible to reduce the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification.

[0090] The molecular weight of the mercapto fatty acid ester (1A) is preferably 400 or less, more preferably 300 or less, and particularly preferably 80 to 300. When the molecular weight of the mercapto fatty acid ester (1A) is within the above range, it becomes possible to disperse the semiconductor nanoparticle composite at a high concentration in a nonpolar solvent.

[0091] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the average SP value of the ligands coordinated to the semiconductor nanoparticles is preferably 9.30 or less. In the present invention, the SP value of the ligand can be calculated from the structural formula using the Y-MB method (the same applies hereinafter).

[0092] When multiple types of ligands are coordinated to a semiconductor nanoparticle, the SP value of each ligand is multiplied by the volume fraction of the ligand, and the sum of these is the average SP value of all the ligands. For example, if a semiconductor nanoparticle is coordinated with P1 volume % of ligands with SP value A1, P2 volume % of ligands with SP value A2, etc., the average SP value of all the ligands is expressed by the following formula (2): Average SP value of all ligands = Σ(Ai × Pi / 100) (2)

[0093] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the mass ratio of the ligand to the semiconductor nanoparticles (ligand / semiconductor nanoparticles) is preferably 0.50 or less, and more preferably 0.40 or less. When the mass ratio of the ligand to the semiconductor nanoparticles (ligand / semiconductor nanoparticles) is within the above range, it becomes possible to disperse the semiconductor nanoparticle composite at a high concentration in a nonpolar solvent.

[0094] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the ligand preferably further comprises an aliphatic ligand. By including an aliphatic ligand in the ligand, the dispersibility of the semiconductor nanoparticle composite in a non-polar dispersion medium can be improved. Examples of the aliphatic ligand include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, and aliphatic amines. In particular, it is preferable that the aliphatic ligand be one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines because of the strength of their coordinating power with the semiconductor nanoparticles.

[0095] The first semiconductor nanoparticle composite of the present invention has the above-mentioned configuration, and thus has dispersibility in non-polar organic solvents. In addition to maintaining a high fluorescence quantum efficiency (QY) before and after purification, the composite has high dispersibility in non-polar organic solvents.

[0096] A semiconductor nanoparticle composite of a second embodiment of the present invention is a semiconductor nanoparticle composite in which R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 14 to 30 carbon atoms in the general formula (1), and the SP value of the mercapto fatty acid ester represented by the general formula (1) is 9.00 or less. That is, the semiconductor nanoparticle composite of the second embodiment of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, the semiconductor nanoparticle containing In and P, and the ligand containing a mercapto fatty acid ester represented by the general formula (1) in which R1 is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 14 to 30 carbon atoms (hereinafter also referred to as mercapto fatty acid ester (1B)), and the SP value of the mercapto fatty acid ester (1B) is 9.00 or less.

[0097] The semiconductor nanoparticle composite of the second embodiment of the present invention has enhanced heat resistance by containing, as a ligand, a mercapto fatty acid ester (1B) in which R1 in general formula (1) is a hydrocarbon group having 1 to 11 carbon atoms and R2 is a hydrocarbon group having 14 to 30 carbon atoms. In particular, the mercapto fatty acid ester (1B) in which R1 is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 14 to 30 carbon atoms enhances the heat resistance of the semiconductor nanoparticle composite. Note that, among the mercapto fatty acid esters (1B), those in which R2 has a carbon number in the range of 14 to 20 also correspond to the mercapto fatty acid ester (1A).

[0098] The carbon number of R1 in the mercapto fatty acid ester (1B) is 1 to 11, preferably 2 to 11. R1 is not particularly limited as long as it has 1 to 11 carbon atoms, and examples thereof include an ethylene group, a propylene group, and a hexyl group. The carbon number of R2 in the mercapto fatty acid ester (1B) is 14 to 30. R2 is not particularly limited as long as it has 14 to 30 carbon atoms, and examples thereof include linear groups such as stearyl, palmityl, eicosal, and octacosal, and branched groups such as 2-n-octyldodecyl. Examples of the mercapto fatty acid ester (1B) include stearyl 3-mercaptopropionate, palmityl 11-mercaptoundecanoate, and octacosal 3-mercaptopropionate.

[0099] In particular, in the semiconductor nanoparticle composite of the second embodiment of the present invention, the mercapto fatty acid ester (1B) is a mercapto fatty acid ester in which R2 in general formula (1) has 14 to 20 carbon atoms, which not only increases the heat resistance of the semiconductor nanoparticle composite but also improves the dispersibility of the semiconductor nanoparticle composite in non-polar solvents.

[0100] The SP value of the mercapto fatty acid ester (1B) is 9.00 or less, preferably 7.00 to 8.60. When the SP value of the mercapto fatty acid ester (1B) is within the above range, the heat resistance of the semiconductor nanoparticle composite is increased.

[0101] In the semiconductor nanoparticle composite of the second embodiment of the present invention, the content of the mercapto fatty acid ester (1B) in the entire ligands is preferably 40.0 mol % or more, more preferably 50.0 mol % or more, and particularly preferably 60.0 mol % or more. By setting the content of the mercapto fatty acid ester (1B) in the entire ligands within the above range, it is possible to reduce the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification.

[0102] The molecular weight of the mercapto fatty acid ester (1B) is preferably 300 to 500, more preferably 350 to 450. When the molecular weight of the mercapto fatty acid ester (1B) is within the above range, it becomes possible to disperse the semiconductor nanoparticle composite at a high concentration in a non-polar solvent.

[0103] In the semiconductor nanoparticle composite of the second embodiment of the present invention, the average SP value of the ligands coordinated to the semiconductor nanoparticles is preferably 9.30 or less. In the present invention, the SP value of the ligand can be calculated from the structural formula using the Y-MB method.

[0104] In the semiconductor nanoparticle composite of the second embodiment of the present invention, the ligand preferably further comprises an aliphatic ligand. By including an aliphatic ligand in the ligand, the dispersibility of the semiconductor nanoparticle composite in a non-polar dispersion medium can be improved. Examples of the aliphatic ligand include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, and aliphatic amines. In particular, it is preferable that the aliphatic ligand be one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines because of the strength of the coordination force with the semiconductor nanoparticles.

[0105] In a heat resistance test of the semiconductor nanoparticle composite of the second embodiment of the present invention for 5 hours at 180±5°C in the atmosphere, the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after the heat resistance test relative to the fluorescence quantum efficiency before the heat resistance test ((1-(fluorescence quantum efficiency after heat resistance test / fluorescence quantum efficiency before heat resistance test))×100) is preferably less than 10%, particularly preferably less than 5%.

[0106] By virtue of having the above-described configuration, the second semiconductor nanoparticle composite of the present invention has dispersibility in non-polar organic solvents, maintains a high fluorescence quantum efficiency (QY) before and after purification, and has high heat resistance.

[0107] By adopting the above-described configuration of the semiconductor nanoparticles of the present invention, it is possible to suppress the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle complex after purification relative to before purification ((1-(fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) × 100) to less than 20%, or even less than 10%.

[0108] The resistance to purification (purification resistance) of the semiconductor nanoparticle composite of the present invention can be calculated by measuring the fluorescence quantum efficiency of a dispersion of semiconductor nanoparticles before purification and a dispersion of the semiconductor nanoparticle composite after purification. The fluorescence quantum efficiency is measured by making the semiconductor nanoparticle concentrations in the dispersions before and after purification the same, and if the fluorescence quantum efficiency before purification is "QYa" and the fluorescence quantum efficiency after purification is "QYb", the rate of change in fluorescence quantum efficiency after purification relative to before purification can be calculated using the following formula (3): {1-(QYb / QYa)}×100 (3) The resistance to refining (refining resistance) can be calculated by the following formula (4). (QYb / QYa)×100 (4)

[0109] That is, a change rate of the fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification of less than 10% indicates that the purification resistance is 90% or more.

[0110] When the semiconductor nanoparticle composite of the present invention has a purification resistance of 80% or more, it is possible to suppress a decrease in fluorescence quantum efficiency due to purification of the semiconductor nanoparticle composite.

[0111] The method for purifying a semiconductor nanoparticle composite of the present invention is a method in which the semiconductor nanoparticle composite of the present invention is aggregated using a poor solvent, and then the semiconductor nanoparticle composite is separated.

[0112] 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 collected 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.

[0113] In the present invention, in addition to the methods described above, methods for purifying semiconductor nanoparticle composites may also include, for example, aggregation, liquid-liquid extraction, distillation, electrodeposition, size exclusion chromatography and / or ultrafiltration, or any other method, used alone or in combination.

[0114] The semiconductor nanoparticle composite of the present invention preferably maintains the structure of the semiconductor nanoparticle composite of the present invention even after purification.

[0115] The fluorescence quantum efficiency (QY) of the semiconductor nanoparticle composite of the present invention after purification is preferably 80% or more, more preferably 85% or more. When the fluorescence quantum efficiency of the purified semiconductor nanoparticle composite is 80% or more, more efficient color conversion can be achieved when the semiconductor nanoparticles are used in applications.

[0116] (Semiconductor nanoparticle composite dispersion) The semiconductor nanoparticle composite of the present invention can be dispersed in an organic dispersion medium to form a semiconductor nanoparticle composite dispersion. In the present invention, the 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 the semiconductor nanoparticle composite dispersed in the dispersion medium is referred to as a semiconductor nanoparticle composite dispersion.

[0117] The semiconductor nanoparticle composite dispersion of the present invention is a semiconductor nanoparticle composite dispersion in which the semiconductor nanoparticle composite of the present invention is dispersed in an organic dispersion medium.

[0118] The organic dispersion medium constituting the semiconductor nanoparticle composite dispersion liquid of the present invention is not particularly limited as long as it disperses the semiconductor nanoparticle composite, and examples thereof include organic solvents such as aliphatic hydrocarbons such as pentane, hexane, cyclohexane, isohexane, heptane, octane, hexadecane, and petroleum ether; alcohols such as methanol, ethanol, propanol, and butanol; ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; esters such as methyl acetate, ethyl acetate, propyl acetate, and butyl acetate; glycol ethers such as propylene glycol monomethyl ether; glycol ether esters such as propylene glycol monomethyl ether acetate; aromatic hydrocarbons such as benzene, toluene, xylene, and mineral spirits; alkyl halides such as dichloromethane, chloroform, and 1,2-dichlorobenzene; and mixed solvents thereof.

[0119] When the semiconductor nanoparticle composite of the present invention has the above-described configuration, the semiconductor nanoparticle composite can be dispersed in a non-polar 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 set to 15 mass% or more, further 20 mass% or more, further 25 mass% or more, or even 35 mass% or more.

[0120] Furthermore, in the present invention, a monomer can be selected as the organic dispersion medium for the semiconductor nanoparticle composite dispersion of the present invention. 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.

[0121] A prepolymer can be selected as the organic dispersion medium for the semiconductor nanoparticle composite dispersion of the present invention. The prepolymer is not particularly limited, but examples thereof include acrylic resin prepolymers, silicone resin prepolymers, and epoxy resin prepolymers.

[0122] (Semiconductor nanoparticle composite composition) In the present invention, a semiconductor nanoparticle composite composition can be formed by selecting a monomer or prepolymer as the dispersion medium for the semiconductor nanoparticle composite dispersion. That is, the semiconductor nanoparticle composite composition of the present invention is a semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite of the present invention is dispersed in a monomer or prepolymer.

[0123] 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.

[0124] Furthermore, the semiconductor nanoparticle composite composition of the present invention may contain a crosslinking agent, which is selected from polyfunctional (meth)acrylates, polyfunctional silane compounds, polyfunctional amines, polyfunctional carboxylic acids, polyfunctional thiols, polyfunctional alcohols, polyfunctional isocyanates, etc., depending on the type of monomer in the semiconductor nanoparticle composite composition.

[0125] Furthermore, the semiconductor nanoparticle composite composition of the present invention can 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 for diluting the semiconductor nanoparticle composite composition, but also as organic dispersion media. 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.

[0126] Furthermore, the semiconductor nanoparticle composite composition of the present invention may contain an appropriate initiator, scattering agent, catalyst, binder, surfactant, adhesion promoter, antioxidant, ultraviolet absorber, anti-aggregation agent, dispersant, etc., depending on the type of monomer in the semiconductor nanoparticle composite composition.

[0127] Furthermore, the semiconductor nanoparticle composite composition of the present invention may contain a scattering agent to improve the optical properties of the semiconductor nanoparticle composite composition or the semiconductor nanoparticle composite cured film described below. 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.

[0128] 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.

[0129] 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.

[0130] (Diluted Composition) The diluted composition is obtained by diluting the above-mentioned semiconductor nanoparticle composite composition of the present invention with an organic solvent.

[0131] The organic solvent used to dilute the semiconductor nanoparticle composite composition is not particularly limited, and examples thereof include aliphatic hydrocarbons, alcohols, ketones, esters, glycol ethers, glycol ether esters, benzene, toluene, aromatic hydrocarbons, and alkyl halides.

[0132] (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.

[0133] The semiconductor nanoparticle composite cured film of the present invention is a semiconductor nanoparticle composite cured film in which the semiconductor nanoparticle composite of the present invention is dispersed in a polymer matrix. That is, the semiconductor nanoparticle composite cured film of the present invention contains semiconductor nanoparticles, ligands coordinated to the surfaces of the semiconductor nanoparticles, and a polymer matrix.

[0134] 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.

[0135] 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.

[0136] 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.

[0137] 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.

[0138] 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, in order to reduce the size of devices to which the semiconductor nanoparticle composite cured film is applied.

[0139] (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.

[0140] 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.

[0141] 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.

[0142] 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]

[0143] 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.

[0144] [Example 1] The semiconductor nanoparticle composite was prepared according to the following method. (Preparation of core particles) 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 (1.1 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.

[0145] (Precursor for shell formation) To prepare the shell, the following precursor was first 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] = 0.4M. (Preparation of Se precursor (trioctylphosphine selenide)) 22 mmol of selenium powder and 10 mL of trioctylphosphine were mixed in a nitrogen atmosphere 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 a nitrogen atmosphere and stirred until completely dissolved to obtain trioctylphosphine sulfide with [S] = 2.2 M. Using each precursor obtained as described above, a shell was formed on the surface of the InP-based semiconductor nanoparticles (core) as follows. (Shell formation) The core dispersion was heated to 200°C. At 250°C, 6.0 mL of Zn precursor solution and 2.0 mL of trioctylphosphine selenide were added and reacted for 30 minutes to form a ZnSe shell on the surface of the InP-based semiconductor nanoparticles. 4.0 mL of Zn precursor solution and 1.8 mL of trioctylphosphine sulfide were then added, and the temperature was raised to 280°C. The reaction was continued for 1 hour to form a ZnS shell. The reaction solution was cooled to room temperature, and 200 mL of dehydrated acetone was added under a nitrogen atmosphere and stirred for 30 minutes. The solution was allowed to stand for 30 minutes, and the supernatant was removed by cannulation. The organic phase containing the semiconductor nanoparticles remaining in the flask was diluted with 5 mL of octadecene. The obtained semiconductor nanoparticles were observed by STEM-EDS and were confirmed to have a core / shell structure.

[0146] (Production of single ligand) (Preparation method of 2-ethylhexyl 6-mercaptohexanoate) A flask was charged with 5.9 g of 6-mercaptohexanoic acid (40 mmol), 6.2 g of 2-ethylhexanol (48 mmol), 100 mL of toluene, and 0.2 g of concentrated sulfuric acid under a nitrogen atmosphere. A Dean-Stark apparatus was attached to the flask, and the solution was stirred at 110 °C for 24 hours. After cooling to room temperature, the reaction solution was washed sequentially with saturated sodium bicarbonate water, water, and saturated brine. The resulting organic phase was dried over magnesium sulfate, filtered, and concentrated by evaporation. The concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the desired ligand (2-ethylhexyl 6-mercaptohexanoate).

[0147] (Method for preparing methyl 11-mercaptoundecanoate) In a flask, 8.7 g of 11-mercaptoundecanoic acid (40 mmol), 26.0 g of methanol (200 mmol), and 0.2 g of concentrated sulfuric acid were mixed under a nitrogen atmosphere. The solution was heated to reflux at 65°C while stirring and reacted for 24 hours. After cooling to room temperature, the reaction solution was dissolved in chloroform and washed sequentially with saturated sodium bicarbonate water, water, and saturated brine. The resulting organic phase was dried over magnesium sulfate, filtered, and concentrated by evaporation to obtain the desired ligand (methyl 11-mercaptoundecanoate).

[0148] (Method for preparing hexyl 3-mercaptopropionate) In a flask, 4.2 g of 3-mercaptopropionic acid (40 mmol), 19.7 g of 1-octacosanol (48 mmol), 100 mL of toluene, and 0.2 g of concentrated sulfuric acid were mixed under a nitrogen atmosphere. The pressure was reduced to below 30 mmHg and the reaction was allowed to proceed for 24 hours. After cooling to room temperature, the reaction solution was dissolved in toluene and washed sequentially with saturated sodium bicarbonate water, water, and saturated brine. The resulting organic phase was dried over magnesium sulfate, filtered, and concentrated by evaporation. The concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the desired ligand (octacosal 3-mercaptopropionic acid).

[0149] (Method for preparing palmityl 11-mercaptoundecanoate) In a flask, 8.7 g of 11-mercaptoundecanoic acid (40 mmol), 6.2 g of palmityl alcohol (48 mmol), and 0.2 g of concentrated sulfuric acid were mixed under a nitrogen atmosphere. The solution was stirred at 60 °C, and the pressure was reduced to less than 30 mmHg, allowing the reaction to proceed for 24 hours. After cooling to room temperature, the reaction solution was dissolved in toluene and washed sequentially with saturated sodium bicarbonate water, water, and saturated saline. The resulting organic phase was dried over magnesium sulfate, filtered, and concentrated by evaporation. The concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the desired ligand (palmityl 11-mercaptoundecanoate).

[0150] (Method for preparing octacosal 3-mercaptopropionate) In a flask, 4.2 g of 3-mercaptopropionic acid (40 mmol), 19.7 g of 1-octacosanol (48 mmol), and 0.2 g of concentrated sulfuric acid were mixed under a nitrogen atmosphere. The solution was stirred at 60 °C, and the pressure was reduced to less than 30 mmHg, allowing the reaction to proceed for 24 hours. After cooling to room temperature, the reaction solution was dissolved in toluene and washed sequentially with saturated aqueous sodium bicarbonate, water, and saturated brine. The resulting organic phase was dried over magnesium sulfate, filtered, and concentrated by evaporation. The concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the desired ligand (octacosal 3-mercaptopropionic acid).

[0151] (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 1.8 g of isooctyl thioglycolate (Tokyo Chemical Industry Co., Ltd.) as a mercapto fatty acid ester and 0.2 g of dodecanethiol as an aliphatic ligand were added. The mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and 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.

[0152] (Fluorescence quantum efficiency measurement) The optical properties of the semiconductor nanoparticle composite were measured using a fluorescence quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics). The semiconductor nanoparticle composite obtained by synthesis was dispersed in a dispersion medium, and a single light of 450 nm was applied as excitation light to obtain an emission spectrum. The fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) were calculated from the emission spectrum after re-excitation correction, which was obtained by removing the re-excitation fluorescence emission spectrum of the fluorescence emitted by re-excitation from the obtained emission spectrum. Octadecene was used as the dispersion medium. Furthermore, 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 three times to obtain a purified semiconductor nanoparticle composite. The purified semiconductor nanoparticle composite was dispersed in a dispersion medium and excited with a single beam of 450 nm to obtain an emission spectrum. The fluorescence quantum efficiency (QY) was calculated from the re-excitation-corrected emission spectrum, which was obtained by subtracting the re-excitation fluorescence emission spectrum from the obtained emission spectrum. The measurement was performed to match the absorbance of the semiconductor nanoparticle composite dispersion before purification. The refining resistance was calculated from the fluorescence quantum efficiency of the semiconductor nanoparticle composite before and after refining. The obtained fluorescence quantum efficiency, the rate of change before and after purification, and the purification resistance are shown in Table 2. Change rate before and after purification (%) = (1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) x 100 Purification resistance (%) = (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification) x 100

[0153] ( 1 H-NMR measurement) The purified semiconductor nanoparticle composites were analyzed for ligands coordinated to the semiconductor nanoparticles using a nuclear magnetic resonance (NMR) spectrometer (JNM-LA400, manufactured by JEOL Ltd.). All measurements were performed using deuterated chloroform as the solvent and tetramethylsilane as the internal chemical shift standard. H-NMR measurements were performed using the semiconductor nanoparticle composite obtained in Synthesis Example 1. Signals attributable to the alkyl groups of dodecanethiol were observed around 0.8 to 1.6 ppm, and signals attributable to the polyethylene glycol backbone were observed around 3.5 to 4.0 ppm. The abundance ratio of each ligand was calculated from the area ratio of these signals. Based on the abundance ratio of each ligand, the average SP value of all ligands and the ratio (mol ratio) of mercapto fatty acid ester to all ligands were calculated. The results are shown in Table 1.

[0154] (Thermogravimetric analysis) 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 this value was used to determine the mass ratio of the semiconductor nanoparticles to the semiconductor nanoparticle composite.

[0155] (Heat resistance test) After removing the solvent from the dispersion of the purified semiconductor nanoparticle composite, the semiconductor nanoparticle composite was placed in a thermostatic chamber (manufactured by Yamato Scientific, DN411H) and subjected to a heat resistance test in air at 180±5°C for 5 hours. The fluorescence quantum efficiency of the semiconductor nanoparticle composite after the heat resistance test was then measured. At this time, the fluorescence quantum efficiency of the semiconductor nanoparticle composite before the heat resistance test was measured. The rate of change before and after the heat resistance test was calculated from the fluorescence quantum efficiency of the semiconductor nanoparticle composite before and after the heat resistance test. The obtained fluorescence quantum efficiency after the heat resistance test and the rate of change before and after the heat resistance test are shown in Table 2. Change rate before and after heat resistance test (%) = (1 - (fluorescence quantum efficiency after heat resistance test / fluorescence quantum efficiency before heat resistance test)) x 100

[0156] (Dispersibility test) With reference to the above mass ratios, an organic dispersion medium was added to the semiconductor nanoparticle composite so that the semiconductor nanoparticle concentrations were 15 mass%, 20 mass%, 30 mass%, and 40 mass%, respectively, and the dispersion state at each stage was confirmed. ○ indicates that the nanoparticles were dispersed, and × indicates that precipitation or turbidity was observed. Normal hexane was used as the dispersion medium. Regarding the evaluation of dispersibility, if the semiconductor nanoparticles are dispersed at a concentration of 15% by mass, they are judged to be dispersible in a non-polar organic solvent, and if the semiconductor nanoparticles are dispersed even at a concentration of 20% by mass, they are judged to have high dispersibility in a non-polar organic solvent.

[0157] [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, 1.8 g of tridecyl 3-mercaptopropionate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the mercapto fatty acid ester and 0.2 g of trioctylphosphine was used as the aliphatic ligand.

[0158] [Example 3] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.6 g of 2-ethylhexyl 6-mercaptohexanoate was used as the mercapto fatty acid ester and 0.4 g of dodecanethiol was used as the aliphatic ligand.

[0159] [Example 4] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.6 g of methyl 11-mercaptoundecanoate was used as the mercapto fatty acid ester and 0.2 g of oleic acid was used as the aliphatic ligand.

[0160] [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, 1.5 g of 2-ethylhexyl 3-mercaptopropionate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the mercapto fatty acid ester and 0.5 g of dodecanethiol was used as the aliphatic ligand.

[0161] [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, 1.1 g of 2-ethylhexyl thioglycolate (manufactured by Tokyo Chemical Industry Co., Ltd.) was used as the mercapto fatty acid ester and 0.9 g of dodecanethiol was used as the aliphatic ligand.

[0162] [Example 7] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 1.8 g of isooctyl thioglycolate was used as the mercapto fatty acid ester and 0.2 g of 6-mercaptohexanol was used as the aliphatic ligand in the step of preparing the semiconductor nanoparticle composite.

[0163] [Example 8] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.8 g of hexyl 3-mercaptopropionate was used as the mercapto fatty acid ester and 0.2 g of oleic acid was used as the aliphatic ligand.

[0164] [Example 9] 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, 2.7 g of stearyl 3-mercaptopropionate (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was used as the mercapto fatty acid ester and 0.3 g of oleic acid was used as the aliphatic ligand.

[0165] [Example 10] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 3.6 g of palmityl 11-mercaptoundecanoate was used as the mercapto fatty acid ester and 0.4 g of oleic acid was used as the aliphatic ligand.

[0166] [Example 11] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the shell-forming reaction, after the ZnSe shell was formed, the Zn precursor solution and trioctylphosphine sulfide were not added and the mixture was cooled to room temperature.

[0167] [Example 12] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.3 g of isooctyl thioglycolate was used as the mercapto fatty acid ester and 0.7 g of benzenethiol was used instead of the aliphatic ligand.

[0168] [Example 13] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 0.9 g of isooctyl thioglycolate was used as the mercapto fatty acid ester and 1.1 g of dodecanethiol was used as the aliphatic ligand.

[0169] [Example 14] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of producing the semiconductor nanoparticle composite, no mercapto fatty acid ester was added and 2.0 g of dodecanethiol was used as the aliphatic ligand.

[0170] [Example 15] In the process of preparing the semiconductor nanoparticle composite, 1.6 g of ethyl 3-mercaptopropionate (Tokyo Chemical Industry Co., Ltd.) as the mercapto fatty acid ester and 0.4 g of dodecanethiol as the aliphatic ligand were used. The mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and then cooled to 25°C. The reaction solution containing the semiconductor nanoparticle composite was transferred to a centrifuge tube and centrifuged at 4000G for 20 minutes, resulting in separation into a transparent octadecene phase and a semiconductor nanoparticle composite phase. The semiconductor nanoparticle composite was recovered, and the fluorescence quantum yield was measured as a chloroform dispersion. Furthermore, 5.0 mL of acetone was added to the semiconductor nanoparticle composite obtained by synthesis 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 three times to obtain a purified semiconductor nanoparticle composite. The fluorescence quantum yield of the purified semiconductor nanoparticle composite was measured as a chloroform dispersion.

[0171] [Example 16] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 3.2 g of octacosal 3-mercaptopropionate was used as the mercapto fatty acid ester and 0.8 g of dodecanethiol was used as the aliphatic ligand.

[0172] [Example 17] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 0.7 g of isooctyl thioglycolate was used as the mercapto fatty acid ester and 1.3 g of dodecanethiol was used as the aliphatic ligand.

[0173] [Example 18] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.6 g of eicosal 3-mercaptopropionate was used as the mercapto fatty acid ester and 0.4 g of dodecanethiol was used as the aliphatic ligand.

[0174] [Example 19] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.6 g of tetraeicosal 3-mercaptopropionate was used as the mercapto fatty acid ester and 0.4 g of dodecanethiol was used as the aliphatic ligand.

[0175] [Example 20] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the step of preparing the semiconductor nanoparticle composite, 1.6 g of 2-n-octyldodecyl 3-mercaptopropionate was used as the mercapto fatty acid ester and 0.4 g of dodecanethiol was used as the aliphatic ligand.

[0176] The meanings of the abbreviations shown in Tables 1 and 2 are as follows: MPAE: mercapto fatty acid ester QD: Semiconductor nanoparticles DDT: Dodecanethiol TOP: Trioctylphosphine

[0177] Table 1

[0178] Table 2

Claims

1. A semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, the semiconductor nanoparticle containing In and P, the ligand containing a mercapto fatty acid ester represented by the following general formula (1) and an aliphatic ligand, the SP value of the mercapto fatty acid ester being 9.30 or less, the content of the mercapto fatty acid ester represented by the general formula (1) in the total ligands being 40.0 mol% or more, and the average SP value of the ligands coordinated to the semiconductor nanoparticles being 9.30 or less. General formula (1): HS-R １ -COOR ２ (1) (In general formula (1), R １ is a hydrocarbon group having 1 to 11 carbon atoms, and R ２ is a hydrocarbon group having 21 to 30 carbon atoms.

2. In the general formula (1), R １ is a hydrocarbon group having 1 to 11 carbon atoms and R ２ is a hydrocarbon group having 21 to 30 carbon atoms, and the SP value of the mercapto fatty acid ester represented by general formula (1) is 9.00 or less.

3. 3. The semiconductor nanoparticle composite according to claim 1, wherein, in a heat resistance test at 180°C for 5 hours in the atmosphere, the rate of change in fluorescence quantum efficiency of the semiconductor nanoparticle composite after the heat resistance test relative to the fluorescence quantum efficiency before the heat resistance test ((1-(fluorescence quantum efficiency after heat resistance test / fluorescence quantum efficiency before heat resistance test)) x 100) is less than 10%.

4. In the general formula (1), R １ is an alkylene group having 1 to 11 carbon atoms, and R ２ The semiconductor nanoparticle composite according to any one of claims 1 to 3, wherein is an alkyl group having 21 to 30 carbon atoms.

5. 5. The semiconductor nanoparticle composite according to claim 1, wherein the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 to 450.

6. The semiconductor nanoparticle composite according to any one of claims 1 to 5, wherein the semiconductor nanoparticles are core / shell type semiconductor nanoparticles having a core mainly composed of In and P and one or more shell layers.

7. 7. The semiconductor nanoparticle composite according to claim 6, wherein at least one of the shells is formed of ZnSe.

8. 8. The semiconductor nanoparticle composite according to claim 6, wherein the shell has two or more layers, and the outermost layer of the shell is formed of ZnS.

9. The semiconductor nanoparticle composite according to any one of claims 6 to 8, characterized in that the shell comprises at least a first shell formed of ZnSe and covering the outer surface of the core, and a second shell formed of ZnS and covering the outer surface of the first shell.

10. 2. The semiconductor nanoparticle composite according to claim 1, wherein the aliphatic ligand is at least one member selected from the group consisting of an aliphatic thiol, an aliphatic carboxylic acid, and an aliphatic phosphine.

11. 11. The semiconductor nanoparticle composite according to claim 1, wherein the content of the mercapto fatty acid ester represented by general formula (1) in the ligand is 50.0 mol % or more.

12. 12. The semiconductor nanoparticle composite according to claim 1, wherein the content of the mercapto fatty acid ester represented by general formula (1) in the ligand is 60.0 mol % or more.

13. The semiconductor nanoparticle composite according to any one of claims 1 to 12, wherein the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification relative to the fluorescence quantum efficiency before purification ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) x 100) is less than 20%.

14. The semiconductor nanoparticle composite according to any one of claims 1 to 13, wherein the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification relative to the fluorescence quantum efficiency before purification ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) x 100) is less than 10%.

15. 15. The semiconductor nanoparticle composite according to claim 1, wherein the semiconductor nanoparticle composite has a fluorescence quantum efficiency of 80% or more after purification.

16. 16. The semiconductor nanoparticle composite according to claim 1, wherein the half width of the emission spectrum of the semiconductor nanoparticle composite is 38 nm or less.

17. A purification method comprising agglomerating the semiconductor nanoparticle composite according to any one of claims 1 to 16 using a poor solvent, and then separating the semiconductor nanoparticle composite.

18. A semiconductor nanoparticle composite dispersion liquid in which the semiconductor nanoparticle composite according to any one of claims 1 to 17 is dispersed in an organic dispersion medium.

19. A semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite according to any one of claims 1 to 17 is dispersed in a dispersion medium, The semiconductor nanoparticle composite composition, wherein the dispersion medium is a monomer or a prepolymer.

20. A semiconductor nanoparticle composite cured film in which the semiconductor nanoparticle composite according to any one of claims 1 to 17 is dispersed in a polymer matrix.

Images