Semiconductor nanoparticle complex, semiconductor nanoparticle complex liquid dispersion, semiconductor nanoparticle complex composition, semiconductor nanoparticle complex cured film, and purification method for semiconductor nanoparticle complex

Abstract

A semiconductor nanoparticle complex having a ligand coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle comprises In and P, the ligand comprises 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. 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.) According to the present invention, it is possible to provide a semiconductor nanoparticle composite that maintains high fluorescence quantum efficiency (QY) before and after purification.

Description

Technology Field

[0001] The present invention relates to a semiconductor nanoparticle composite. Background Technology

[0002] As the quantum confinement effect is manifested, minute semiconductor nanoparticles (quantum dots, QDs) have a band gap that depends on the particle size. Since excitons formed within semiconductor nanoparticles by means such as photoexcitation or charge injection emit photons with energy corresponding to the band gap through recombination, luminescence at a desired wavelength can be obtained by appropriately selecting the composition and particle size of the semiconductor nanoparticles.

[0003] In the early stages of research on semiconductor nanoparticles, studies focused on elements containing Cd or Pb. However, since Cd and Pb are regulated substances subject to restrictions on the use of specific hazardous substances, research on non-Cd and non-Pb semiconductor nanoparticles has recently been conducted.

[0004] Semiconductor nanoparticles are being explored for various applications, including displays, biomarkers, and solar cells. For display applications, applications such as QD films, QD patterning, and self-emissive devices (QLEDs) are anticipated. Prior art literature

[0005] Specification of U.S. Patent Application Publication No. 2008 / 0308130 and Japanese Patent Publication No. 2002-121549 The problem to be solved

[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, regarding applications in display fields such as QD films, QD patterning, and self-emissive devices (QLEDs), nonpolar semiconductor nanoparticles are most commonly used with hexane or octane as the dual solvent (dispersion medium with high solubility) and acetone or ethanol as the non-solvent (dispersion medium with low solubility). As disclosed in Patent Document 1, these nonpolar semiconductor nanoparticles are purified by repeating the operation of dispersing them in the dual solvent after synthesis and then precipitating them in the non-solvent. In the purification process of nonpolar semiconductor nanoparticles, there was a problem that the fluorescence quantum efficiency was prone to deterioration due to the influence of moisture, etc., because the non-solvent of the nonpolar semiconductor nanoparticles is a polar solvent.

[0007] Semiconductor nanoparticles include group II-VI semiconductor nanoparticles known as CdSe-based or group III-V semiconductor nanoparticles known as InP-based. To obtain high fluorescence quantum efficiency, these semiconductor nanoparticles may have a core-shell structure by using the aforementioned semiconductor nanoparticle as a core particle and forming a shell on the surface of the core particle. Since group II-VI semiconductors such as ZnSe or ZnS are mainly used for the shell from the perspective of quantum confinement effects, when the core is a group II-VI core particle, epitaxial growth is easy and uniform shell formation is possible because the valence of the core particle and the shell-forming element is common. On the other hand, when the core is a group III-V core particle, it is difficult to form a uniform shell because the valence of the core particle and the shell-forming element is different. This point also affects the resistance of semiconductor nanoparticles to purification, and as mentioned above, while research on non-Cd semiconductor nanoparticles has been conducted recently, III-V group / II-VI group core / shell type semiconductor nanoparticles have lower resistance to purification compared to II-VI group / II-VI group core / shell type semiconductor nanoparticles, and there was a problem of reduced fluorescence quantum efficiency after purification.

[0008] Furthermore, when forming cured films such as QD films and QD patterning, any curing method is used to cure the dispersion; however, if the curing method is thermal curing, heat is applied to the dispersion of the semiconductor nanoparticle composite, so heat resistance is required for the semiconductor nanoparticles and the semiconductor nanoparticle composite. Therefore, in addition to resistance to purification, high heat resistance is sometimes required for the semiconductor nanoparticle composite.

[0009] Therefore, the first objective of the present invention is to provide a semiconductor nanoparticle composite that has dispersibility in non-polar organic solvents and maintains high fluorescence quantum efficiency (QY) before and after purification, in order to solve the above-mentioned problems. Furthermore, the present invention aims to provide a semiconductor nanoparticle composite that has high dispersibility in non-polar organic solvents in addition to having dispersibility in non-polar organic solvents and maintaining high fluorescence quantum efficiency (QY) before and after purification. Furthermore, the present invention aims to provide a semiconductor nanoparticle composite that has high heat resistance in addition to having dispersibility in non-polar organic solvents and maintaining high fluorescence quantum efficiency (QY) before and after purification. Additionally, the present invention aims to provide a semiconductor nanoparticle composite that maintains high fluorescence quantum efficiency (QY) before and after purification, has high dispersibility in non-polar organic solvents, and also has high heat resistance. means of solving the problem

[0010] That is, the present invention (1) provides a semiconductor nanoparticle complex in which a ligand is coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle comprises In and P, the ligand comprises 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):

[0012] HS-R1-COOR2(1)

[0013] (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.)

[0014] In addition, the present invention (2) provides a semiconductor nanoparticle composite characterized in that, in (1), R1 in the 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, 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.

[0015] In addition, the present invention (3) provides a semiconductor nanoparticle composite characterized in that, in (2), R1 in the general formula (1) is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 1 to 20 carbon atoms.

[0016] In addition, the present invention (4) provides a semiconductor nanoparticle composite characterized in that, in (2) or (3), the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 400 or less.

[0017] In addition, the present invention (5) provides a semiconductor nanoparticle composite characterized in that, in (2) or (3), the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 or less.

[0018] In addition, the present invention (6) provides a semiconductor nanoparticle composite characterized in that, in any one of (2) to (5), the mass ratio (ligand / semiconductor nanoparticle) of the ligand and the semiconductor nanoparticle is 0.50 or less.

[0019] In addition, the present invention (7) provides a semiconductor nanoparticle composite characterized in that, in any one of (2) to (6), the mass ratio (ligand / semiconductor nanoparticle) of the ligand and the semiconductor nanoparticle is 0.40 or less.

[0020] In addition, the present invention (8) provides a semiconductor nanoparticle composite characterized in that, in (1), R1 in the 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, and the SP value of the mercapto fatty acid ester represented by the general formula (1) is 9.00 or less.

[0021] In addition, the present invention (9) provides a semiconductor nanoparticle composite characterized in that, in the heat resistance test of (8) at 180°C for 5 hours, the rate of change of the fluorescence quantum efficiency after the heat resistance test ((1 - (fluorescence quantum efficiency after the heat resistance test / fluorescence quantum efficiency before the heat resistance test)) × 100) to the fluorescence quantum efficiency before the heat resistance test of the semiconductor nanoparticle composite is less than 10%.

[0022] In addition, the present invention (10) provides a semiconductor nanoparticle composite characterized in that, in (8) or (9), the content of the mercapto fatty acid ester represented by the general formula (1) in the total ligand is 40.0 mol% or more.

[0023] In addition, the present invention (11) provides a semiconductor nanoparticle composite characterized in that, in any one of (8) to (10), R1 in the general formula (1) is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 14 to 30 carbon atoms.

[0024] In addition, the present invention (12) provides a semiconductor nanoparticle composite characterized in that, in any one of (8) to (11), the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 to 450.

[0025] In addition, the present invention (13) provides a semiconductor nanoparticle composite in which, in any one of (1) to (12), the semiconductor nanoparticle is a core / shell type semiconductor nanoparticle having a core composed mainly of In and P and one or more shell layers.

[0026] In addition, the present invention (14) provides a semiconductor nanoparticle composite characterized in that, in (13), at least one of the shells is formed of ZnSe.

[0027] In addition, the present invention (15) provides a semiconductor nanoparticle composite characterized in that, in (13) or (14), the shell has two or more layers, and the outermost layer of the shell is formed of ZnS.

[0028] In addition, the present invention (16) provides a semiconductor nanoparticle composite in which, in any one of (13) to (15), the shell is formed of at least ZnSe and consists of a first shell covering the outer surface of the core and a second shell formed of ZnS and covering the outer surface of the first shell.

[0029] In addition, the present invention (17) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (16), the average SP value of the ligand coordinated to the semiconductor nanoparticle is 9.3 or less.

[0030] In addition, the present invention (18) provides a semiconductor nanoparticle complex characterized in that, in any one of (1) to (17), the ligand additionally comprises an aliphatic ligand.

[0031] In addition, the present invention (19) provides a semiconductor nanoparticle composite characterized in that, in (18), the aliphatic ligand is one or more selected from the group consisting of aliphatic thiol, aliphatic carboxylic acid and aliphatic phosphine.

[0032] In addition, the present invention (20) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (19), the content of the mercapto fatty acid ester represented by the general formula (1) in the ligand is 50.0 mol% or more.

[0033] In addition, the present invention (21) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (20), the content of the mercapto fatty acid ester represented by the general formula (1) in the ligand is 60.0 mol% or more.

[0034] In addition, the present invention (22) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (21), the rate of change of the fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification of the semiconductor nanoparticle composite ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) × 100) is less than 20%.

[0035] In addition, the present invention (23) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (22), the rate of change of the fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification of the semiconductor nanoparticle composite ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) × 100) is less than 10%.

[0036] In addition, the present invention (24) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (23), the fluorescence quantum efficiency after purification of the semiconductor nanoparticle composite is 80% or more.

[0037] In addition, the present invention (25) provides a semiconductor nanoparticle composite characterized in that, in any one of (1) to (24), the half-width of the emission spectrum of the semiconductor nanoparticle composite is 38 nm or less.

[0038] In addition, the present invention (26) provides a purification method characterized by aggregating a semiconductor nanoparticle complex described in any one of (1) to (25) using a solvent, and then separating the semiconductor nanoparticle complex.

[0039] In addition, the present invention (27) provides a semiconductor nanoparticle composite dispersion in which a semiconductor nanoparticle composite described in any one of (1) to (25) is dispersed in an organic dispersion medium.

[0040] In addition, the present invention (28) is a semiconductor nanoparticle composite composition in which a semiconductor nanoparticle composite described in any one of (1) to (25) is dispersed in a dispersion medium, and

[0041] The present invention provides a semiconductor nanoparticle composite composition characterized in that the dispersion medium is a monomer or a prepolymer.

[0042] In addition, the present invention (29) provides a semiconductor nanoparticle composite cured film in which a semiconductor nanoparticle composite described in any one of (1) to (25) is dispersed in a polymer matrix.

[0043] In addition, the range indicated by “~” in this document shall be the range including the numbers indicated at both ends. Effects of the invention

[0044] According to the present invention, a semiconductor nanoparticle composite having dispersibility in non-polar organic solvents and maintaining high fluorescence quantum efficiency (QY) before and after purification can be provided. Furthermore, the present invention can provide a semiconductor nanoparticle composite having high dispersibility in non-polar organic solvents in addition to having dispersibility in non-polar organic solvents and maintaining high fluorescence quantum efficiency (QY) before and after purification. Furthermore, the present invention can provide a semiconductor nanoparticle composite having high heat resistance in addition to having dispersibility in non-polar organic solvents and maintaining high fluorescence quantum efficiency (QY) before and after purification. Furthermore, the present invention can provide a semiconductor nanoparticle composite having high fluorescence quantum efficiency (QY) before and after purification, high dispersibility in non-polar organic solvents, and high heat resistance. Specific details for implementing the invention

[0045] (Semiconductor nanoparticle complex)

[0046] The present invention relates to a semiconductor nanoparticle complex in which a ligand is coordinated to the surface of a semiconductor nanoparticle. In the present invention, the semiconductor nanoparticle complex is a semiconductor nanoparticle complex having luminescent properties. The semiconductor nanoparticle complex of the present invention is a particle that absorbs light of 340 nm to 480 nm and emits light with a luminescence peak wavelength of 400 nm to 750 nm.

[0047] 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, wherein the semiconductor nanoparticle comprises In and P, and the ligand is of the following general formula (1):

[0048] HS-R1-COOR2(1)

[0049] (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.)

[0050] The semiconductor nanoparticle composite is characterized by including a mercapto fatty acid ester represented by the above general formula (1), wherein the SP value of the mercapto fatty acid ester represented by the above general formula (1) is 9.30 or less.

[0051] The semiconductor nanoparticle composite of the present invention comprises a semiconductor nanoparticle and a ligand coordinated to the surface of the semiconductor nanoparticle.

[0052] The semiconductor nanoparticle composite of the present invention is capable of maintaining 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 maintains high fluorescence quantum efficiency after purification, and the rate of change in fluorescence quantum efficiency before and after purification is small.

[0053] 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, both before and after purification, and further preferably 35 nm or less. In particular, since the full width at half maximum of the emission spectrum of the semiconductor nanoparticle composite of the present invention after purification is within the above range, color mixing can be reduced when the semiconductor nanoparticle composite is applied to displays, etc.

[0054] The fluorescence quantum efficiency (QY) of the semiconductor nanoparticle composite of the present invention is preferably 80% or higher before or after purification, and more preferably 85% or higher. In particular, since the fluorescence quantum efficiency of the semiconductor nanoparticle composite of the present invention after purification is 80% or higher, color conversion can be performed more efficiently 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.

[0055] In the present invention, the optical properties of a semiconductor nanoparticle composite can be measured using a quantum efficiency measurement system. A semiconductor nanoparticle composite is dispersed in a dispersion and irradiated with excitation light to obtain an emission spectrum. From the emission spectrum obtained therefrom, the fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) are calculated from the emission spectrum after re-excitation correction, excluding the re-excitation fluorescence emission spectrum corresponding to the amount of fluorescence emission that occurred upon re-excitation. Examples of dispersions include normal hexane.

[0056] -Semiconductor Nanoparticles-

[0057] The semiconductor nanoparticles constituting the semiconductor nanoparticle complex of the present invention, that is, the particles to which ligands are coordinated, contain Group III elements and Group V elements. In particular, from the perspective of luminescence properties and safety, it is preferable that the semiconductor nanoparticles contain In and P.

[0058] From the perspective of quantum confinement effects, as semiconductor nanoparticles, core / shell type semiconductor nanoparticles having one or more shell layers and a semiconductor nanoparticle containing In and P as a core particle are preferred. As core / shell type semiconductor nanoparticles, it is more preferable to have two or more shell layers. It is preferable for the shell to have a composition including Zn and Se, and it is preferable that at least one of the shells is formed of ZnSe. When the core / shell type semiconductor nanoparticle has two or more shell layers, it is preferable for the outermost layer to be a shell with a composition including Zn and S, and it is more preferable for it to be formed of ZnS. In particular, when the shell is formed of at least ZnSe and consists of a first shell 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.

[0059] As long as it does not impair the effects of the present invention, the composition in the shell does not necessarily have to be stoichiometric, and each shell may contain elements other than Zn, Se, and S, and may have one or more gradient shells in which the ratio of the elements constituting the shell changes.

[0060] Here, in the present invention, whether the shell covers at least a portion of the core or the elemental distribution inside the shell can be confirmed by analyzing the composition using, for example, energy dispersive X-ray spectroscopy (TEM-EDX) using a transmission electron microscope.

[0061] Examples of methods for fabricating semiconductor nanoparticles are disclosed below.

[0062] A core of a semiconductor nanoparticle can be formed by heating a precursor mixture obtained by mixing an In precursor, a P precursor, and optionally additives in a solvent.

[0063] Coordinating solvents or non-coordinating solvents are used as solvents. Examples of solvents include 1-octadecene, hexadecane, squalene, oleylamine, trioctylphosphine, and trioctylphosphine oxide.

[0064] Examples of precursors of In include acetates, carboxylates, and halides containing In, but are not limited to these.

[0065] Examples of precursors of P include organic compounds or gases containing P, but are not limited to these. When the precursor is a gas, a core can be formed by reacting the gas while injecting it into a precursor mixture containing substances other than the gas.

[0066] Semiconductor nanoparticles may include one or more elements other than In and P, provided that they do not impair the effects of the present invention, and in such cases, a precursor of the said element may be added when forming the core.

[0067] Examples of additives include, for instance, carboxylic acids, amines, thiols, phosphines, phosphine oxides, phosphinic acids, and phosphonic acids as dispersants, but are not limited to these. The dispersant may also serve as a solvent.

[0068] After forming the core of the semiconductor nanoparticles, the luminescence properties of the semiconductor nanoparticles can be enhanced by adding halides as needed.

[0069] In one embodiment, a metal precursor solution containing an In precursor and, if necessary, a dispersant is added to a solvent is mixed under vacuum, heated at 100°C to 300°C for 6 to 24 hours, then additionally a P precursor is added and heated at 200°C to 400°C for 3 to 60 minutes, and then cooled. Additionally, a halogen precursor is added and heat treated at 25°C to 300°C, preferably 100°C to 300°C, more preferably 150°C to 280°C, thereby obtaining a core particle dispersion containing core particles.

[0070] By adding a shell-forming precursor to a synthesized core particle dispersion, the semiconductor nanoparticles can adopt a core-shell structure, thereby increasing fluorescence quantum efficiency (QY) and stability.

[0071] It is thought that the elements constituting the shell take on structures such as alloys, heterostructures, or amorphous structures on the surface of the core particles, and it can also be assumed that some move into the interior of the core particles by diffusion.

[0072] The added shell-forming elements are primarily located near the surface of the core particles and serve to protect the semiconductor nanoparticles from external factors. In the core-shell structure of the semiconductor nanoparticles, it is preferable that the shell covers at least a portion of the core, and more preferably, that it uniformly covers the entire surface of the core particles.

[0073] In one embodiment, a Zn precursor and a Se precursor are added to the aforementioned core particle dispersion, and then heated at 150°C to 300°C, preferably 180°C to 250°C, and then a Zn precursor and an S precursor are added, and then heated at 200°C to 400°C, preferably 250°C to 350°C. By doing so, core-shell type semiconductor nanoparticles can be obtained.

[0074] Here, although not specifically limited, as a Zn precursor, carboxylates such as zinc acetate, zinc propionate, and zinc myristate, halides such as zinc chloride and zinc bromide, and organic salts such as diethyl zinc may be used.

[0075] As Se precursors, phosphine selenides such as tributylphosphine selenide, trioctylphosphine selenide, and tris(trimethylsilyl)phosphine selenide, selenos such as benzene selenol and selenocysteine, and selen / octadecene solutions can be used.

[0076] As S precursors, 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.

[0077] The shell precursors may be mixed in advance and added all at once or in multiple stages, or added separately, either all at once or in multiple stages. When adding the shell precursors in multiple stages, the temperature may be changed and heated after each shell precursor is added.

[0078] In the present invention, the method for producing semiconductor nanoparticles is not particularly limited, and in addition to the method described above, conventional methods such as hot injection, homogeneous solvent method, reverse micelle method, CVD method, or any other method may be adopted.

[0079] -Ligand-

[0080] The semiconductor nanoparticle composite of the present invention comprises a ligand coordinated to the surface of the semiconductor nanoparticle. The term "coordination" as used herein refers to the ligand chemically influencing the surface of the semiconductor nanoparticle. The ligand may be bonded to the surface of the semiconductor nanoparticle via a coordinate bond or any other bonding method (e.g., covalent bond, ionic bond, hydrogen bond, etc.), or, if the ligand is present on at least a portion of the surface of the semiconductor nanoparticle, it is not necessary for the ligand to form a bond.

[0081] In the semiconductor nanoparticle composite of the present invention, the ligand coordinated to the semiconductor nanoparticle comprises a mercapto fatty acid ester represented by the following general formula (1).

[0082] General formula (1):

[0083] HS-R1-COOR2(1)

[0084] 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. In general formula (1), R1 is not particularly limited and may be an alkylene group. In addition, the alkylene group may have a branched structure. In addition, in general formula (1), R2 is not particularly limited and may be, for example, a hydrocarbon group having 1 to 20 carbon atoms, a hydrocarbon group having 14 to 30 carbon atoms, or a hydrocarbon group having 14 to 20 carbon atoms, and more specifically, an alkyl group, an alkenyl group, or an alkynyl group. The alkyl group, an alkenyl group, or an alkynyl group may have a branched structure. By having R1 and R2 in general formula (1) as described above, the rate of change in fluorescence quantum efficiency of the semiconductor nanoparticle composite before purification is reduced. The mercapto fatty acid ester represented by general formula (1) may be a single type or a combination of two or more types.

[0085] As disclosed in Patent Document 2, mercapto fatty acid esters are used as ligands that enable dispersion of semiconductor nanoparticles into polar solvents. In the present invention, the inventors have discovered that by coordinating a mercapto fatty acid ester represented by general formula (1) to semiconductor nanoparticles, dispersibility into non-polar solvents is maintained, resulting in high initial fluorescence quantum efficiency and a small rate of change in fluorescence quantum efficiency after purification compared to before purification.

[0086] In addition, 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. Since the SP value of the mercapto fatty acid ester is 9.30 or less, it becomes possible to disperse semiconductor nanoparticles in a non-polar solvent at a high mass fraction.

[0087] Here, the SP value of the ligand can be determined by calculating it using the Y-MB method.

[0088] In the semiconductor nanoparticle composite of the present invention, the mercapto fatty acid ester represented by general formula (1) is preferably one in which R1 is an alkylene group having 1 to 11 carbon atoms and R2 is an alkyl group having 1 to 30 carbon atoms, in that it has excellent dispersibility in a non-polar solvent.

[0089] 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.

[0090] 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 ligand 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 ligand to the above range, the effect of reducing the rate of change in fluorescence quantum efficiency after purification compared to before purification of the semiconductor nanoparticle composite is enhanced.

[0091] In the semiconductor nanoparticle composite of the present invention, it is preferable that the average SP value of the ligands coordinated to the semiconductor nanoparticles is 9.30 or less. The SP value of the ligands can be calculated from the structural formula using the Y-MB method.

[0092] When there are multiple types of ligands coordinated to semiconductor nanoparticles, the SP value of each ligand is multiplied by the volume fraction of the ligand, and then the total average SP value of all ligands is added together to be the SP value of the ligands. For example, when a ligand with SP value A1 is coordinated to a semiconductor nanoparticle in P1 volume%, a ligand with SP value A2 is coordinated in P2 volume%, ..., the total average SP value of all ligands is expressed by the following equation (2).

[0093] Average SP value of all ligands = Σ(Ai×Pi / 100) (2)

[0094] In the semiconductor nanoparticle composite of the present invention, it is preferable that the ligand additionally include an aliphatic ligand. By including an aliphatic ligand, dispersibility in a nonpolar dispersion medium is enhanced. Furthermore, the aliphatic ligand may include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, aliphatic amines, etc., but in particular, it is preferable that it be one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines based on the strength of the coordination force with the semiconductor nanoparticles.

[0095] The semiconductor nanoparticle composite of the present invention, by having the above composition, has dispersibility in non-polar organic solvents and can also maintain high fluorescence quantum efficiency (QY) before and after purification.

[0096] The semiconductor nanoparticle composite of the first form of the present invention is such 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 total ligand is 40.0 mol% or more. That is, the semiconductor nanoparticle composite of the first form 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 comprises In and P, and the ligand comprises a mercapto fatty acid ester represented by the general formula (1), wherein 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)), wherein 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 total ligand is 40.0 mol% or more.

[0097] The semiconductor nanoparticle composite of the first embodiment of the present invention has improved dispersibility in a non-polar organic solvent by including a mercapto fatty acid ester (1A) as a ligand, wherein R1 in the 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) has R1 as an alkylene group having 1 to 11 carbon atoms and R2 as an alkyl group having 1 to 20 carbon atoms, thereby facilitating the dispersion of the semiconductor nanoparticle composite in a non-polar solvent.

[0098] The number of carbon atoms in R1 of the mercapto fatty acid ester (1A) is 1 to 11, preferably 2 to 6, and R1 is not particularly limited as long as the number of carbon atoms is 1 to 11, for example, as a straight-chain group, ethylene group, propylene group, hexyl group, etc., and as a branched group, 1,2-propylene group, etc., can be used. Also, the number of carbon atoms in R2 of the mercapto fatty acid ester (1A) is 1 to 20, and R2 is not particularly limited as long as the number of carbon atoms is 1 to 20, for example, as a straight-chain group, methyl group, hexyl group, octyl group, stearyl group, palmityl group, eicosal group, etc., can be used, and as a branched group, ethylhexyl group, 2-n-octyldodecyl group, etc., can be used. As for the mercapto fatty acid ester (1A), R1 and R2 both need to satisfy the aforementioned number of carbon atoms, and are not particularly limited, examples include isooctyl thioglycolate, tridecyl 3-mercaptopropionic acid, ethylhexyl 6-mercaptohexanoate, and methyl 11-mercaptoundecanonate.

[0099] In particular, in the first embodiment of the semiconductor nanoparticle composite of the present invention, the mercapto fatty acid ester (1A) is a mercapto fatty acid ester having 14 to 20 carbon atoms in R2 of the general formula (1), so in addition to high dispersion of the semiconductor nanoparticle composite in a non-polar solvent, the heat resistance of the semiconductor nanoparticle composite is increased.

[0100] The SP value of the mercapto fatty acid ester (1A) is 9.30 or less, preferably 7.00 to 9.20. By having the SP value of the mercapto fatty acid ester (1A) within the above range, the dispersibility of the semiconductor nanoparticle composite in a non-polar organic solvent is increased.

[0101] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the content of the mercapto fatty acid ester (1A) in the total ligand is 40.0 mol% or more, preferably 50.0 mol% or more, more preferably 60.0 mol% or more. By setting the content of the mercapto fatty acid ester (1A) in the total ligand to the above range, the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification can be reduced.

[0102] 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. By having the molecular weight of the mercapto fatty acid ester (1A) within the above range, it becomes possible to disperse the semiconductor nanoparticle complex at a high concentration in a non-polar solvent.

[0103] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the average SP value of the ligand coordinated to the semiconductor nanoparticle is preferably 9.30 or less. In addition, in the present invention, the SP value of the ligand can be calculated from the structural formula using the Y-MB method (hereinafter the same).

[0104] When there are multiple types of ligands coordinated to semiconductor nanoparticles, the SP value of each ligand is multiplied by the volume fraction of the ligand, and then the total average SP value of all ligands is added together to be the SP value of the ligands. For example, when a ligand with SP value A1 is coordinated to a semiconductor nanoparticle in P1 volume%, a ligand with SP value A2 is coordinated in P2 volume%, ..., the total average SP value of all ligands is expressed by the following equation (2).

[0105] Average SP value of all ligands = Σ(Ai×Pi / 100) (2)

[0106] In the semiconductor nanoparticle composite of the first embodiment of the present invention, the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is preferably 0.50 or less, and more preferably 0.40 or less. By having the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) within the above range, it becomes possible to disperse the semiconductor nanoparticle composite at a high concentration in a non-polar solvent.

[0107] In the semiconductor nanoparticle composite of the first embodiment of the present invention, it is preferable that the ligand additionally include an aliphatic ligand. By including an aliphatic ligand, the dispersibility of the semiconductor nanoparticle composite in a nonpolar dispersion medium can be increased. Furthermore, examples of aliphatic ligands include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, aliphatic amines, etc., and in particular, it is preferable that one or more are selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines based on the strength of the coordination force with the semiconductor nanoparticles.

[0108] The first semiconductor nanoparticle composite of the present invention, by having the above configuration, has dispersibility in a non-polar organic solvent and maintains a high fluorescence quantum efficiency (QY) before and after purification, in addition to having high dispersibility in a non-polar organic solvent.

[0109] A semiconductor nanoparticle composite of the second form of the present invention is 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. That is, the semiconductor nanoparticle composite of the second form 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 comprises In and P, and the ligand comprises a mercapto fatty acid ester represented by the general formula (1), wherein 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.

[0110] The second embodiment of the semiconductor nanoparticle composite of the present invention has increased heat resistance by including a mercapto fatty acid ester (1B) as a ligand, wherein R1 in the 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 heat resistance of the semiconductor nanoparticle composite is increased by the fact that the mercapto fatty acid ester (1B) has R1 as an alkylene group having 1 to 11 carbon atoms and R2 as an alkyl group having 14 to 30 carbon atoms. Furthermore, among the mercapto fatty acid esters (1B), the one in which R2 has 14 to 20 carbon atoms corresponds to the mercapto fatty acid ester (1A).

[0111] The number of carbon atoms in R1 of the mercapto fatty acid ester (1B) is 1 to 11, preferably 2 to 11, and R1 is not particularly limited as long as the number of carbon atoms is 1 to 11, and examples include an ethylene group, a propylene group, a hexyl group, etc. Also, the number of carbon atoms in R2 of the mercapto fatty acid ester (1B) is 14 to 30, and R2 is not particularly limited as long as the number of carbon atoms is 14 to 30, and examples include a stearyl group, a palmityl group, an eicosal group, an octacosal group, etc. as a straight-chain group, and a 2-n-octyldodecyl group, etc. as a branched-chain group. Examples of the mercapto fatty acid ester (1B) include 3-mercaptopropionic acid stearyl, 11-mercaptoundecanonic acid palmityl, 3-mercaptopropionic acid octacosal, etc.

[0112] In particular, in the second form of the semiconductor nanoparticle composite of the present invention, the mercapto fatty acid ester (1B) is a mercapto fatty acid ester having 14 to 20 carbon atoms in R2 of the general formula (1), so in addition to increasing the heat resistance of the semiconductor nanoparticle composite, the dispersion of the semiconductor nanoparticle composite into a non-polar solvent is increased.

[0113] The SP value of the mercapto fatty acid ester (1B) is 9.00 or less, preferably 7.00 to 8.60. By having the SP value of the mercapto fatty acid ester (1B) within the above range, the heat resistance of the semiconductor nanoparticle composite is increased.

[0114] In the semiconductor nanoparticle composite of the second embodiment of the present invention, the content of the mercapto fatty acid ester (1B) in the total ligand 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 total ligand to the above range, the rate of change in the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification compared to before purification can be reduced.

[0115] The molecular weight of the mercapto fatty acid ester (1B) is preferably 300 to 500, and more preferably 350 to 450. By having the molecular weight of the mercapto fatty acid ester (1B) within the above range, it becomes possible to disperse the semiconductor nanoparticle complex at a high concentration in a non-polar solvent.

[0116] In the semiconductor nanoparticle composite of the second embodiment of the present invention, the average SP value of the ligand coordinated to the semiconductor nanoparticle is preferably 9.30 or less. In addition, in the present invention, the SP value of the ligand can be calculated from the structural formula using the Y-MB method.

[0117] In the semiconductor nanoparticle composite of the second embodiment of the present invention, it is preferable that the ligand additionally include an aliphatic ligand. By including an aliphatic ligand, the dispersibility of the semiconductor nanoparticle composite in a nonpolar dispersion medium can be increased. Furthermore, examples of aliphatic ligands include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, aliphatic amines, etc. In particular, it is preferable that one or more are selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines based on the strength of the coordination force with the semiconductor nanoparticles.

[0118] In the second embodiment of the semiconductor nanoparticle composite of the present invention, in a heat resistance test of 180±5℃ for 5 hours in air, the rate of change of fluorescence quantum efficiency after the heat resistance test relative to the fluorescence quantum efficiency before the heat resistance test of the semiconductor nanoparticle composite ((1-(fluorescence quantum efficiency after the heat resistance test / fluorescence quantum efficiency before the heat resistance test))×100) is preferably less than 10%, particularly preferably less than 5%.

[0119] The second semiconductor nanoparticle composite of the present invention, by having the above composition, has dispersibility in non-polar organic solvents and maintains high fluorescence quantum efficiency (QY) before and after purification, in addition to having high heat resistance.

[0120] By adopting the above-described configuration, the semiconductor nanoparticles of the present invention can 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%, and furthermore, less than 10%.

[0121] The resistance to purification (purification resistance) of the semiconductor nanoparticle composite of the present invention can be calculated by measuring the fluorescence quantum efficiency for the dispersion of the semiconductor nanoparticles before purification and the dispersion of the semiconductor nanoparticle composite after purification. By measuring the fluorescence quantum efficiency with the concentration of semiconductor nanoparticles in the dispersions before and after purification equalized, and if the fluorescence quantum efficiency before purification is denoted as “QYa” and the fluorescence quantum efficiency after purification is denoted as “QYb”, the rate of change of the fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification can be calculated by the following equation (3).

[0122] {1-(QYb / QYa)}×100 (3)

[0123] In addition, resistance to tablets (tablet resistance) can be calculated by the following formula (4).

[0124] (QYb / QYa)×100 (4)

[0125] In other words, the rate of change of fluorescence quantum efficiency after purification relative to fluorescence quantum efficiency before purification is less than 10%, which indicates that the purification resistance is 90% or higher.

[0126] Since the semiconductor nanoparticle composite of the present invention has a purification resistance of 80% or more, the decrease in fluorescence quantum efficiency caused by purification of the semiconductor nanoparticle composite can be suppressed.

[0127] The purification method of the semiconductor nanoparticle complex of the present invention is a method of separating the semiconductor nanoparticle complex of the present invention after aggregating it using a solvent-free solvent.

[0128] In one embodiment, a semiconductor nanoparticle composite can be precipitated from a dispersion by adding a polarity-changing solvent such as acetone. The precipitated semiconductor nanoparticle composite can be recovered by filtration or centrifugation, and the supernatant containing unreacted starting materials and other impurities can be discarded or reused. Subsequently, the precipitated semiconductor nanoparticle composite can be washed with a new dispersion medium and dispersed again. This purification process can be repeated, for example, 2 to 4 times, or until a desired purity is reached.

[0129] In the present invention, as a method for purifying a semiconductor nanoparticle composite, in addition to the method described above, for example, aggregation, liquid-liquid extraction, distillation, electrodeposition, size exclusion chromatography and / or ultrafiltration, or any other method may be used alone or in combination.

[0130] It is preferable that the semiconductor nanoparticle composite of the present invention has the structure of the semiconductor nanoparticle composite of the present invention even after purification.

[0131] The fluorescence quantum efficiency (QY) of the semiconductor nanoparticle composite of the present invention after purification is preferably 80% or higher, and more preferably 85% or higher. Since the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification is 80% or higher, color conversion can be performed more efficiently when using semiconductor nanoparticles in applications.

[0132] (Semiconductor nanoparticle complex dispersion)

[0133] 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 is mixed with the dispersion medium, the semiconductor nanoparticle composite does not precipitate or does not remain as a visually observable turbidity. Furthermore, the state in which the semiconductor nanoparticle composite is dispersed in a dispersion medium is referred to as a semiconductor nanoparticle composite dispersion.

[0134] The semiconductor nanoparticle complex dispersion of the present invention is a semiconductor nanoparticle complex dispersion in which the semiconductor nanoparticle complex of the present invention is dispersed in an organic dispersion medium.

[0135] The organic dispersion medium constituting the semiconductor nanoparticle composite dispersion of the present invention is not particularly limited as long as the semiconductor nanoparticle composite is dispersed therein, and examples 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; or mixed solvents thereof.

[0136] By having the above-described configuration of the semiconductor nanoparticle composite of the present invention, 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 15 mass% or more, 20 mass% or more, 25 mass% or more, and 35 mass% or more.

[0137] In addition, in the present invention, a monomer may be selected as the organic dispersion medium of the semiconductor nanoparticle composite dispersion of the present invention. The monomer is not particularly limited, but it is preferred to be a (meth)acrylic monomer that allows for a wide selection of applications for the semiconductor nanoparticles. Depending on the application of semiconductor nanoparticle composite dispersions, (meth)acrylates include 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, dicyclofentanyl (meth)acrylate, and dicyclofentenyl (meth)acrylate. Methoxyethyl (meth)acrylate, ethyl carbitol (meth)acrylate, methoxytriethylene glycol acrylate, 2-ethylhexyl diglycol acrylate, methoxypolyethylene glycol acrylate, methoxydipropylene 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, dicyclofentanyloxyethyl (meth)acrylate, isobornyloxyethyl (meth)acrylate, Adamantyl (meth)acrylate, dimethyladamanthyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, benzyl (meth)acrylate, ω-carboxy-polycaprolactone(n≒2)monoacrylate, 2-hydroxy-3-phenoxypropylacrylate, 2-hydroxy-3-phenoxyethyl (meth)acrylate, (2-methyl-2-ethyl-1,3-dioxolane-4-yl)methyl (meth)acrylate, (3-ethyloxetane-3-yl)methyl (meth)acrylate,It is selected from (meth)acrylate monomers such as o-phenylphenol ethoxy(meth)acrylate, dimethylamino(meth)acrylate, diethylamino(meth)acrylate, 2-(meth)acryloyloxyethylphthalic acid, 2-(meth)acryloyloxyethylhexahydrophthalic acid, glycidyl(meth)acrylate, 2-(meth)acryloyloxyethylphosphate, acryloylmorpholine, dimethylacrylamide, dimethylaminopropylacrylamide, isopropylacrylamide, diethylacrylamide, hydroxyethylacrylamide, and N-acryloyloxyethylhexahydrophthalimide. These may be used alone or in combination of two or more types. In particular, depending on the application of the semiconductor nanoparticle composite dispersion, 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.

[0138] In addition, a prepolymer may be selected as the organic dispersion medium of the semiconductor nanoparticle composite dispersion of the present invention. The prepolymer is not particularly limited, but examples include acrylic resin prepolymers, silicone resin prepolymers, and epoxy resin prepolymers.

[0139] (Semiconductor nanoparticle complex composition)

[0140] In the present invention, a semiconductor nanoparticle composite composition can be formed by selecting a monomer or a prepolymer as the dispersion medium of 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 a prepolymer.

[0141] Monomers or prepolymers are not particularly limited, but may include radical polymerizable compounds containing ethylenically unsaturated bonds, siloxane compounds, epoxy compounds, isocyanate compounds, and phenol derivatives.

[0142] In addition, the semiconductor nanoparticle composite composition of the present invention may contain a crosslinking agent. Depending on the type of monomer in 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, and polyfunctional isocyanates.

[0143] In addition, the semiconductor nanoparticle composite composition of the present invention may further include various organic solvents that do not affect curing, such as aliphatic hydrocarbons including pentane, hexane, cyclohexane, isohexane, heptane, octane, and petroleum ethers; alcohols; ketones; esters; glycol ethers; glycol ether esters; aromatic hydrocarbons including benzene, toluene, xylene, and mineral spirits; and alkyl halides including dichloromethane and chloroform. Furthermore, the above organic solvents may be used not only for diluting the semiconductor nanoparticle composite composition but also as organic dispersion media. That is, it is also possible to disperse the semiconductor nanoparticle composite of the present invention in the above organic solvent to form a semiconductor nanoparticle composite dispersion.

[0144] In addition, the semiconductor nanoparticle composite composition of the present invention may include appropriate initiators, scattering agents, catalysts, binders, surfactants, adhesion promoters, antioxidants, ultraviolet absorbers, anti-aggregation agents, and dispersants, depending on the type of monomer in the semiconductor nanoparticle composite composition.

[0145] In addition, 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 of the present invention may include a scattering agent. The scattering agent is a metal oxide such as titanium oxide or zinc oxide, and it is preferable that the particle size of the scattering agent is 100 nm to 500 nm. From the perspective of the scattering effect, it is more preferable that the particle size of the scattering agent is 200 nm to 400 nm. By including a scattering agent, the absorbance is improved by about twofold. The content of the scattering agent is preferably 2 mass% to 30 mass% with respect to the composition, and it is more preferable to be 5 mass% to 20 mass% from the perspective of maintaining the patternability of the composition.

[0146] By the composition of the semiconductor nanoparticle composite of the present invention, the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite composition can 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 composite and semiconductor nanoparticles can be dispersed in a high mass fraction even in the cured film described later.

[0147] The semiconductor nanoparticle composite composition of the present invention, when made into a 10 μm film, preferably has an absorbance of 1.0 or higher for light of a wavelength of 450 nm from the normal direction of the film, more preferably 1.3 or higher, and even more preferably 1.5 or higher. As a result, since the light of the backlight can be efficiently absorbed, the thickness of the cured film described later can be reduced, and thus the device to which it is applied can be miniaturized.

[0148] (Diluted composition)

[0149] The diluted composition is formed by diluting the semiconductor nanoparticle composite composition of the present invention described above with an organic solvent.

[0150] The organic solvent used to dilute the semiconductor nanoparticle composite composition is not particularly limited, and examples include aliphatic hydrocarbons, alcohols, ketones, esters, glycol ethers, glycol ether esters, benzene, toluene, aromatic hydrocarbons, alkyl halides, etc.

[0151] (Semiconductor nanoparticle composite cured film)

[0152] In the present invention, a semiconductor nanoparticle composite cured film refers to a film containing a semiconductor nanoparticle composite that is cured. The semiconductor nanoparticle composite cured film can be obtained by curing the aforementioned semiconductor nanoparticle composite composition or diluted composition into a film shape.

[0153] 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 comprises semiconductor nanoparticles, ligands coordinated to the surface of the semiconductor nanoparticles, and a polymer matrix.

[0154] There are no particular limitations on the polymer matrix, but examples include (meth)acrylic resin, silicone resin, epoxy resin, silicone resin, maleic acid resin, butyral resin, polyester resin, melamine resin, phenolic resin, polyurethane resin, etc. Additionally, a semiconductor nanoparticle composite cured film may be obtained by curing the aforementioned semiconductor nanoparticle composite composition. The semiconductor nanoparticle composite cured film may additionally include a crosslinking agent.

[0155] The method for curing the film is not particularly limited, and it can be cured by a curing method suitable for the composition constituting the film, such as heat treatment or UV treatment.

[0156] It is preferable that the semiconductor nanoparticles and the ligands coordinated to the surface of the semiconductor nanoparticles, which are included in the semiconductor nanoparticle composite cured film of the present invention, constitute the semiconductor nanoparticle composite described above. By configuring the semiconductor nanoparticle composite included 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.

[0157] In addition, since the semiconductor nanoparticle composite cured film of the present invention contains a semiconductor nanoparticle composite having high luminescence characteristics, a semiconductor nanoparticle composite cured film with high luminescence characteristics can be provided. The fluorescence quantum efficiency of the semiconductor nanoparticle composite cured film is preferably 70% or higher, and more preferably 80% or higher.

[0158] In order to miniaturize the device 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.

[0159] (Semiconductor nanoparticle composite patterning film and display device)

[0160] A semiconductor nanoparticle composite patterning film can be obtained by patterning the aforementioned semiconductor nanoparticle composite composition or dilution composition into a film shape. The method of patterning the semiconductor nanoparticle composite composition and dilution composition is not particularly limited, and examples include spin coating, bar coating, inkjet, screen printing, and photolithography.

[0161] The display device utilizes the above-described semiconductor nanoparticle composite patterning film. For example, by using the semiconductor nanoparticle composite patterning film as a wavelength conversion layer, a display device having excellent fluorescence quantum efficiency can be provided.

[0162] The configurations and / or methods described herein are presented as examples, and since numerous variations are possible, it will be understood that specific examples or embodiments thereof should not be construed as limiting. A specific sequence or method described herein may represent one of a number of processing methods. Accordingly, various actions described and / or described may be performed in the order described and / or described, or may be omitted. Likewise, the order of the aforementioned methods may be changed.

[0163] The subject matter of this disclosure includes all novel and non-obvious combinations and secondary combinations of various methods, systems and configurations disclosed in this specification, and other features, functions, acts and / or qualities, and all equivalents thereof.

[0164] Examples

[0165] The present invention will be specifically explained below through examples and comparative examples, but the present invention is not limited thereto.

[0166] [Example 1]

[0167] A semiconductor nanoparticle composite was fabricated according to the following method.

[0168] (Production of core particles)

[0169] 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), heated to about 120°C under vacuum (<20 Pa), and reacted for 1 hour. The mixture reacted under vacuum was heated to 25°C under a nitrogen atmosphere, tris(trimethylsilyl)phosphine (0.2 mmol) was added, heated to about 300°C, and reacted for 10 minutes. The reaction solution was cooled to 25°C, octanoate (1.1 mmol) was injected, heated to about 250°C for 30 minutes, and then cooled to 25°C to obtain a dispersion of InP-based semiconductor nanoparticles.

[0170] (Precursor for shell formation)

[0171] In the production of the shell, the following precursors were first prepared.

[0172] (Preparation of Zn precursor solution)

[0173] 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.

[0174] (Preparation of Se precursor (trioctylphosphine selenide))

[0175] 22 mmol of selenium powder and 10 mL of trioctylphosphine were mixed under nitrogen and stirred until all dissolved to obtain selenized trioctylphosphine with [Se]=2.2 M.

[0176] (Preparation of S precursor (trioctylphosphine sulfide))

[0177] 22 mmol of sulfur powder and 10 mL of trioctylphosphine were mixed under nitrogen and stirred until all dissolved to obtain [S]=2.2 M trioctylphosphine sulfide.

[0178] Using each precursor obtained as described above, a shell was formed on the surface of the InP-based semiconductor nanoparticle (core) as follows.

[0179] (Formation of shells)

[0180] The dispersion of the core was heated to 200°C. At 250°C, 6.0 mL of a 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. Additionally, 4.0 mL of a Zn precursor solution and 1.8 mL of trioctylphosphine sulfide were added, the temperature was raised to 280°C, and the mixture was reacted 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 left standing 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.

[0181] As a result of observing the obtained semiconductor nanoparticles by STEM-EDS, it was confirmed that they have a core / shell structure.

[0182] (Production of ligand groups)

[0183] (Method for preparing 2-ethylhexyl 6-mercaptohexanoic acid)

[0184] 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 were mixed in a flask under a nitrogen atmosphere. A Dean-Stark apparatus was fitted to the flask, and the solution was reacted at 110°C for 24 hours while stirring. After cooling the reaction solution to room temperature, it was washed sequentially with saturated sodium bicarbonate, water, and saturated saline solution. The resulting organic phase was dried using magnesium sulfate, filtered, and concentrated by evaporation. This concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the target ligand (2-ethylhexyl 6-mercaptohexanoic acid).

[0185] (Method for adjusting methyl 11-mercaptoundecanoate)

[0186] 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 in a flask under a nitrogen atmosphere. The solution was heated at 65°C under reflux and stirred for 24 hours. After cooling the reaction solution to room temperature, it was dissolved in chloroform and washed sequentially with saturated sodium bicarbonate, water, and saturated saline solution. The resulting organic phase was dried using magnesium sulfate, filtered, and concentrated by evaporation to obtain the target ligand (methyl mercaptoundecanoic acid).

[0187] (Method for preparing hexyl 3-mercaptopropionate)

[0188] 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 in a flask under a nitrogen atmosphere. The reaction was carried out for 24 hours under reduced pressure of 30 mmHg or less. After cooling the reaction solution to room temperature, it was dissolved in toluene and washed sequentially with saturated sodium bicarbonate, water, and saturated saline solution. The obtained organic phase was dried using magnesium sulfate, filtered, and concentrated by evaporation. This concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the target ligand (3-mercaptopropionic acid octacosal).

[0189] (Method for adjusting 11-mercaptoundecanonic acid palmityl)

[0190] 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 in a flask under a nitrogen atmosphere. The solution was reacted for 24 hours at 60°C under reduced pressure of 30 mmHg or less while stirring. After cooling the reaction solution to room temperature, it was dissolved in toluene and washed sequentially with saturated sodium bicarbonate, water, and saturated saline solution. The obtained organic phase was dried using magnesium sulfate, filtered, and concentrated by evaporation. This concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the target ligand (palmityl 11-mercaptoundecanoic acid).

[0191] (Method for adjusting octacosal 3-mercaptopropionic acid)

[0192] 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 in a flask under a nitrogen atmosphere. The solution was reacted for 24 hours at 60°C under reduced pressure of 30 mmHg or less while stirring. After cooling the reaction solution to room temperature, it was dissolved in toluene and washed sequentially with saturated sodium bicarbonate, water, and saturated saline solution. The obtained organic phase was dried using magnesium sulfate, filtered, and concentrated by evaporation. This concentrate was purified by column chromatography using hexane and ethyl acetate as developing solvents to obtain the target ligand (3-mercaptopropionic acid octacosal).

[0193] (Fabrication of semiconductor nanoparticle complexes)

[0194] A semiconductor nanoparticle 1-octadecene dispersion was prepared by dispersing purified semiconductor nanoparticles in 1-octadecene at a mass ratio of 10 mass% in a flask. 10.0 g of the prepared semiconductor nanoparticle 1-octadecene dispersion was placed in the flask, 1.8 g of isooctyl thioglycolate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) as a mercapto fatty acid ester and 0.2 g of dodecanethiol as an aliphatic ligand were added, and the mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and cooled to 25°C to obtain a semiconductor nanoparticle complex. The reaction solution containing the semiconductor nanoparticle complex was transferred to a centrifuge tube and centrifuged at 4000 G for 20 minutes, separating it into a transparent 1-octadecene phase and a semiconductor nanoparticle complex phase. The 1-octadecene phase was removed, and the remaining semiconductor nanoparticle complex phase was recovered.

[0195] (Fluorescence Quantum Efficiency Measurement)

[0196] The optical properties of the semiconductor nanoparticle composite were measured using a fluorescence quantum efficiency measurement system (QE-2100, manufactured by Otsuka Electronics). A single 450 nm light was irradiated as an excitation light onto a dispersion in which the semiconductor nanoparticle composite obtained by synthesis was dispersed in a dispersion medium to obtain an emission spectrum. From the emission spectrum obtained here, the fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) were calculated from the emission spectrum after re-excitation correction, by excluding the re-excitation fluorescence emission spectrum corresponding to the amount of fluorescence emission that occurred upon re-excitation. Octadecene was used as the dispersion medium.

[0197] In addition, 5.0 mL of acetone was added to the obtained semiconductor nanoparticle composite 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 recovered. This operation was repeated three times to obtain a purified semiconductor nanoparticle composite. The purified semiconductor nanoparticle composite was dispersed in a dispersion medium, and a single 450 nm light was irradiated as an excitation light to obtain an emission spectrum. From the emission spectrum obtained here, the fluorescence quantum efficiency (QY) was calculated from the emission spectrum after re-excitation correction, excluding the re-excitation fluorescence emission spectrum corresponding to the amount of fluorescence emission that occurred upon re-excitation. At this time, the measurement was performed by equalizing the absorbance with that of the dispersion of the semiconductor nanoparticle composite before purification.

[0198] Purification resistance was calculated from the fluorescence quantum efficiency of the semiconductor nanoparticle complex before and after purification.

[0199] The obtained fluorescence quantum efficiency, rate of change before and after purification, and purification resistance are listed in Table 2.

[0200] · Rate of change before and after purification (%) = (1 - (Fluorescence quantum efficiency after purification / Fluorescence quantum efficiency before purification)) × 100

[0201] · Purification resistance (%) = (Fluorescence quantum efficiency after purification / Fluorescence quantum efficiency before purification) × 100

[0202] ( 1 H-NMR measurement)

[0203] For the purified semiconductor nanoparticle complex, the ligands coordinated to the semiconductor nanoparticles were analyzed using a nuclear magnetic resonance (NMR) device (JNM-LA400 manufactured by Nippon Electronics, Inc.). For all measurements, heavy chloroform was used as the solvent and tetramethylsilane was used as the standard for chemical shift, 1H-NMR was measured. From the semiconductor nanoparticle composite obtained in Synthesis Example 1, a signal attributed to the alkyl group of dodecanethiol was observed at around 0.8–1.6 ppm, and a signal attributed to the polyethylene glycol backbone was observed at around 3.5–4.0 ppm. The abundance of each ligand was calculated from the area ratio of these signals. Based on the abundance of each ligand, the average SP value of all ligands and the ratio (mol ratio) of mercapto fatty acid esters to all ligands were calculated. The obtained results are listed in Table 1.

[0204] (Thermogravimetric analysis)

[0205] The purified semiconductor nanoparticle composite was heated to 550°C for thermogravimetric analysis (DTA-TG), held 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.

[0206] (Heat resistance test)

[0207] After removing the solvent from the dispersion of the semiconductor nanoparticle composite after purification, the semiconductor nanoparticle composite was placed in a constant temperature bath (manufactured by Yamato Kagaku, DN411H) and a heat resistance test was performed at 180±5°C for 5 hours in the atmosphere. Subsequently, the fluorescence quantum efficiency of the semiconductor nanoparticle composite after the heat resistance test was measured. At this time, the fluorescence quantum efficiency of the semiconductor nanoparticle composite before the heat resistance test was measured.

[0208] 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.

[0209] The obtained fluorescence quantum efficiency after the heat resistance test and the rate of change before and after the heat resistance test are listed in Table 2.

[0210] · Rate of change before and after heat resistance test (%) = (1 - (Fluorescence quantum efficiency after heat resistance test / Fluorescence quantum efficiency before heat resistance test)) × 100

[0211] (Dispersion test)

[0212] With reference to the above mass ratios, an organic dispersion medium was added to the semiconductor nanoparticle composites such that the concentration of semiconductor nanoparticles was 15 mass%, 20 mass%, 30 mass%, and 40 mass%, respectively, and the dispersion state was checked. In Table 2, ○ was indicated for dispersed samples, and × was indicated for samples where precipitation or turbidity was observed. In addition, normal hexane was used as the dispersion medium.

[0213] In addition, regarding the evaluation of dispersibility, if the semiconductor nanoparticles are dispersed at a concentration of 15 mass%, dispersion in a non-polar organic solvent is possible, and if the semiconductor nanoparticles are dispersed at a concentration of 20 mass%, it is judged that the dispersibility in a non-polar organic solvent is high.

[0214] [Example 2]

[0215] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.8 g of 3-mercaptopropionic acid tridecyl (manufactured by Fujifilm Wako Co., Ltd.) was used as a mercapto fatty acid ester and 0.2 g of trioctylphosphine was used as an aliphatic ligand.

[0216] [Example 3]

[0217] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.6 g of 6-mercaptohexanoic acid 2-ethylhexyl was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand.

[0218] [Example 4]

[0219] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.6 g of methyl 11-mercaptoundecanonate was used as a mercapto fatty acid ester and 0.2 g of oleic acid was used as an aliphatic ligand.

[0220] [Example 5]

[0221] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.5 g of 3-mercaptopropionic acid 2-ethylhexyl (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used as a mercapto fatty acid ester and 0.5 g of dodecanethiol was used as an aliphatic ligand.

[0222] [Example 6]

[0223] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.1 g of thioglycolic acid 2-ethylhexyl (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used as a mercapto fatty acid ester and 0.9 g of dodecanethiol was used as an aliphatic ligand.

[0224] [Example 7]

[0225] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.8 g of isooctyl thioglycolate was used as a mercapto fatty acid ester and 0.2 g of 6-mercaptohexanol was used as an aliphatic ligand.

[0226] [Example 8]

[0227] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.8 g of 3-mercaptopropionic acid hexyl was used as a mercapto fatty acid ester and 0.2 g of oleic acid was used as an aliphatic ligand.

[0228] [Example 9]

[0229] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 2.7 g of 3-mercaptopropionic acid stearyl (manufactured by Fujifilm Wako Co., Ltd.) was used as a mercapto fatty acid ester and 0.3 g of oleic acid was used as an aliphatic ligand.

[0230] [Example 10]

[0231] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 3.6 g of 11-mercaptoundecanonic acid palmityl was used as a mercapto fatty acid ester and 0.4 g of oleic acid was used as an aliphatic ligand in the process of fabricating the semiconductor nanoparticle complex.

[0232] [Example 11]

[0233] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that in the shell formation reaction, after forming a ZnSe shell, the Zn precursor solution and trioctylphosphine sulfide were not added and the mixture was cooled to room temperature.

[0234] [Example 12]

[0235] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.3 g of isooctyl thioglycolate was used as a mercapto fatty acid ester and 0.7 g of benzenethiol was used as a substitute for an aliphatic ligand.

[0236] [Example 13]

[0237] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 0.9 g of isooctyl thioglycolate was used as a mercapto fatty acid ester and 1.1 g of dodecanethiol was used as an aliphatic ligand.

[0238] [Example 14]

[0239] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, mercapto fatty acid ester was not added and 2.0 g of dodecanethiol was used as an aliphatic ligand.

[0240] [Example 15]

[0241] In the process of preparing a semiconductor nanoparticle complex, 1.6 g of 3-mercaptopropionate (manufactured by Tokyo Kasei Kogyo Co., Ltd.) was used as a mercapto fatty acid ester, and 0.4 g of dodecanethiol was used as an aliphatic ligand. The mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and cooled to 25°C. The reaction solution containing the semiconductor nanoparticle complex was transferred to a centrifuge tube and centrifuged at 4000 G for 20 minutes, separating into a transparent octadecene phase and a semiconductor nanoparticle complex phase. The semiconductor nanoparticle complex was recovered, and the fluorescence quantum yield was measured using a chloroform dispersion. Additionally, 5.0 mL of acetone was added to the semiconductor nanoparticle complex obtained by synthesis 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 transparent supernatant was removed, and the precipitate was recovered. This operation 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.

[0242] [Example 16]

[0243] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 3.2 g of 3-mercaptopropionic acid octacosal was used as a mercapto fatty acid ester and 0.8 g of dodecanethiol was used as an aliphatic ligand.

[0244] [Example 17]

[0245] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 0.7 g of isooctyl thioglycolate was used as a mercapto fatty acid ester and 1.3 g of dodecanethiol was used as an aliphatic ligand.

[0246] [Example 18]

[0247] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.6 g of 3-mercaptopropionic acid eicosal was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand.

[0248] [Example 19]

[0249] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.6 g of 3-mercaptopropionic acid tetraeicosal was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand.

[0250] [Example 20]

[0251] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that in the process of fabricating the semiconductor nanoparticle complex, 1.6 g of 3-mercaptopropionic acid 2-n-octyldodecyl was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand.

[0252] In addition, the meanings of the abbreviations shown in Tables 1 and 2 are as follows.

[0253] MPAE: Mercapto fatty acid ester

[0254] QD: Semiconductor nanoparticles

[0255] DDT: Dodecanethiol

[0256] TOP: Trioctylphosphine

[0257] [Table 1]

[0258]

[0259] [Table 2]

[0260]

Claims

Claim 1 A semiconductor nanoparticle complex in which a ligand is coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle comprises In and P, the ligand comprises a mercapto fatty acid ester represented by the following general formula (1), and the SP value of the mercapto fatty acid ester is 9.00 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 21 to 30 carbon atoms.) Claim 2 A semiconductor nanoparticle composite according to claim 1, characterized in that, in a heat resistance test at 180°C for 5 hours in air, the rate of change of fluorescence quantum efficiency after the heat resistance test relative to the fluorescence quantum efficiency before the heat resistance test ((1 - (fluorescence quantum efficiency after the heat resistance test / fluorescence quantum efficiency before the heat resistance test)) × 100) is less than 10%. Claim 3 A semiconductor nanoparticle composite according to claim 1, characterized in that the content of the mercapto fatty acid ester represented by the general formula (1) in the total ligand is 40.0 mol% or more. Claim 4 A semiconductor nanoparticle composite according to claim 1, 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 21 to 30 carbon atoms. Claim 5 A semiconductor nanoparticle composite according to claim 1, characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 to 450. Claim 6 A semiconductor nanoparticle composite according to claim 1, characterized in that the semiconductor nanoparticle is a core / shell type semiconductor nanoparticle having a core composed mainly of In and P and one or more shell layers. Claim 7 A semiconductor nanoparticle composite according to claim 6, characterized in that at least one of the shells is formed of ZnSe. Claim 8 A semiconductor nanoparticle composite according to claim 6, characterized in that the shell has two or more layers, and the outermost layer of the shell is formed of ZnS. Claim 9 A semiconductor nanoparticle composite according to claim 6, 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. Claim 10 A semiconductor nanoparticle composite according to claim 1, characterized in that the average SP value of the ligand coordinated to the semiconductor nanoparticle is 9.30 or less. Claim 11 A semiconductor nanoparticle complex according to claim 1, characterized in that the ligand further comprises an aliphatic ligand. Claim 12 A semiconductor nanoparticle composite according to claim 11, characterized in that the aliphatic ligand is one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines. Claim 13 A semiconductor nanoparticle composite according to claim 1, 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. Claim 14 A semiconductor nanoparticle composite according to claim 1, 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. Claim 15 A semiconductor nanoparticle composite according to claim 1, characterized in that the rate of change of fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification of the semiconductor nanoparticle composite ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) × 100) is less than 20%. Claim 16 A semiconductor nanoparticle composite according to claim 1, characterized in that the rate of change of the fluorescence quantum efficiency after purification relative to the fluorescence quantum efficiency before purification of the semiconductor nanoparticle composite ((1 - (fluorescence quantum efficiency after purification / fluorescence quantum efficiency before purification)) × 100) is less than 10%. Claim 17 A semiconductor nanoparticle composite according to claim 1, characterized in that the fluorescence quantum efficiency of the semiconductor nanoparticle composite after purification is 80% or more. Claim 18 A semiconductor nanoparticle composite according to claim 1, characterized in that the full width at half maximum of the emission spectrum of the semiconductor nanoparticle composite is 38 nm or less. Claim 19 A purification method characterized by aggregating the semiconductor nanoparticle complex described in claim 1 using a non-solvent, and then separating the semiconductor nanoparticle complex. Claim 20 A semiconductor nanoparticle complex dispersion in which the semiconductor nanoparticle complex described in claim 1 is dispersed in an organic dispersion medium. Claim 21 A semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite described in claim 1 is dispersed in a dispersion medium, wherein the dispersion medium is a monomer or a prepolymer. Claim 22 A semiconductor nanoparticle composite cured film in which the semiconductor nanoparticle composite described in claim 1 is dispersed in a polymer matrix.

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