Semiconductor nanoparticle complex, semiconductor nanoparticle complex liquid dispersion, semiconductor nanoparticle complex composition, and semiconductor nanoparticle complex cured film

Abstract

A semiconductor nanoparticle complex in which a ligand is coordinated on the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shells, wherein the semiconductor nanoparticle additionally contains a halogen, wherein the molar ratio of the halogen to In in terms of atomic value in the semiconductor nanoparticle is 0.80 to 15.00, and the ligand comprises one or more mercapto fatty acid esters represented by the following general formula (1): HS-R1-COO-R2 (1), wherein the SP value of the mercapto fatty acid ester is 9.20 or higher, the molecular weight of the mercapto fatty acid ester is 700 or lower, and the average SP value of the entire ligand is 9.10 to 11.00. According to the present invention, a semiconductor nanoparticle composite capable of being dispersed in a high mass fraction in a polar dispersion medium while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles is provided.

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.

[0005] FIG. 2 illustrates a schematic diagram of a device configuration for converting wavelengths from a light source in a conventional display. As shown in FIG. 2, a blue LED (101) is used as the light source, and first, this blue light is converted into white light. For the conversion from blue light to white light, a QD film (102) formed by dispersing semiconductor nanoparticles in a resin and forming a film shape with a thickness of about 100 μm is appropriately used. The white light obtained by the wavelength conversion layer such as the QD film (102) is further converted into red light, green light, and blue light by a color filter (R) (104), a color filter (G) (105), and a color filter (B) (106), respectively. Also, in FIG. 2, a polarizer is omitted.

[0006] Recently, as illustrated in FIG. 1, the development of a type of display (deflection plate not illustrated) that uses QD patterning as a wavelength conversion layer without using a QD film is underway. In the type of display illustrated in FIG. 1, blue light from a blue LED (1), which is a light source, is not converted into white light, but is directly converted from blue light to red light or from blue light to green light using QD patterning (7, 8). QD patterning (7, 8) is formed by patterning semiconductor nanoparticles dispersed in a resin, and the thickness is about 5 μm to 10 μm due to structural limitations of the display. In addition, for blue light, blue light from a blue LED (1), which is a light source, is used after passing through a diffusion layer (9) containing a diffusion agent. Prior art literature

[0007] Japanese Patent Publication No. 2013-136498

[0008] Author Jin Tasaki, "Semiconductor Quantum Dots, Their Synthesis Methods and Applications in Life Sciences," Production and Technology, Vol. 63, No. 2, pp. 58-63, 2011. Fabien Dubois et al, "A Versatile Strategy for Quantum Dot Ligand Exchange," J. AM. CHEM. SOC Vol. 129, No. 3, pp. 482-483, 2007. Boon-Kin Pong et al, "Modified Ligand-Exchange for Efficient Solubilization of CdSe / ZnS Quantum Dots in Water: A Procedure Guided by Computational Studies," Langmuir Vol. 24, No. 10, pp. 5270-5276, 2008. Samsungida Abd. Rahman et al, "Thiolate-Capped CdSe / ZnS Core-Shell Quantum Dots for the Sensitive Detection of Glucose" Sensors Vol.17, No.7, p.1537, 2017Whitney Nowak Wenger et al, "Functionalization of Cadmium Selenide Quantum Dots with Poly(ethylene glycol): Ligand Exchange, Surface Coverage, and Dispersion Stability" Langmuir, Vol.33, No.33, pp8239-8245, 2017 The problem to be solved

[0009] Semiconductor nanoparticles and semiconductor nanoparticle composites are generally dispersed in a dispersion medium to form a dispersion solution, and are applied in various fields. In particular, for display applications, a dispersion solution dispersed in a polar organic dispersion medium such as glycol ethers and glycol ether esters is used, and the dispersion solution is cured to form a cured film such as a QD film and QD patterning. Furthermore, in order to increase wavelength conversion efficiency, it is required that the mass fraction of semiconductor nanoparticles in the cured film be high.

[0010] However, semiconductor nanoparticles and semiconductor nanoparticle composites synthesized in nonpolar dispersion media were easy to disperse into nonpolar dispersion media due to their high hydrophobicity, but difficult to disperse into polar dispersion media.

[0011] Semiconductor nanoparticles and semiconductor nanoparticle complexes synthesized in non-polar dispersion media are presumed to have weak inter-dipole forces or hydrogen bonding forces. Consequently, even among polar dispersion media, semiconductor nanoparticles can be dispersed in toluene and chloroform, which have weak inter-dipole forces or hydrogen bonding forces, similar to semiconductor nanoparticles synthesized in organic solvents. However, these polar dispersion media are highly toxic, so they are not practical.

[0012] A ligand exchange method is known as a method for enabling semiconductor nanoparticles to be dispersed in a polar dispersion medium. The ligand exchange method is a method of replacing a ligand included in a semiconductor nanoparticle complex obtained by binding a ligand to the surface of a semiconductor nanoparticle with a ligand having a hydrophilic group. The semiconductor nanoparticle complex obtained by this method can be dispersed in a polar dispersion medium. However, the semiconductor nanoparticle complexes disclosed in Non-Patent Literatures 1 to 5 and Patent Literature 1 had a problem in that although dispersion of semiconductor nanoparticles into a polar dispersion medium was possible, the luminescence efficiency was reduced.

[0013] In addition, encapsulation is known as a method to enable the dispersion of semiconductor nanoparticles in a polar dispersion medium; however, since encapsulation involves coating an amphiphilic polymer onto a semiconductor nanoparticle complex obtained by binding ligands to the surface of semiconductor nanoparticles, the amount of dispersant relative to the semiconductor nanoparticles increases, making it difficult to achieve a high mass fraction of semiconductor nanoparticles, and thus making its application difficult.

[0014] For this reason, semiconductor nanoparticle composites are required to be able to be dispersed at a high mass fraction in a polar dispersion medium while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles.

[0015] In addition, when forming a cured film such as a QD film 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.

[0016] In addition, when forming a cured film such as a QD film and QD patterning, any curing method is used to cure the dispersion, but depending on the curing method (e.g., for inkjet), it is sometimes required that the dispersion have low viscosity.

[0017] Accordingly, the object of the present invention is to provide a semiconductor nanoparticle composite capable of being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles. Furthermore, the object of the present invention is to provide a semiconductor nanoparticle composite that, in addition to being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles, has high heat resistance and is useful for applications requiring heat resistance. Furthermore, the object of the present invention is to provide a semiconductor nanoparticle composite that, in addition to being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles, has low viscosity of the dispersion when dispersed in the dispersion medium and is useful for applications requiring low viscosity of the dispersion. means of solving the problem

[0018] The above problem is solved by the present invention below.

[0019] That is, the semiconductor nanoparticle composite (1) of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated on the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, and

[0020] The semiconductor nanoparticles further comprise a halogen, and in the semiconductor nanoparticles, the molar ratio of the halogen to In on an atomic basis is 0.80 to 15.00, and

[0021] The above ligand is the following general formula (1):

[0022] HS-R1-COO-R2(1)

[0023] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0024] The SP value of the above mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the above mercapto fatty acid ester is 700 or lower, and

[0025] In addition, the average SP value of all the above ligands is 9.10 to 11.00.

[0026] The purpose is to provide a semiconductor nanoparticle complex characterized by

[0027] In addition, the present invention (2) provides a semiconductor nanoparticle composite of (1) characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 or more and 700 or less.

[0028] In addition, the present invention (3) provides a semiconductor nanoparticle composite of (1) characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is 300 or more and 600 or less.

[0029] In addition, the present invention (4) provides a semiconductor nanoparticle composite of (2) or (3) characterized in that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 1.00 or less.

[0030] In addition, the present invention (5) provides a semiconductor nanoparticle composite of (2) or (3) characterized in that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 0.70 or less.

[0031] In addition, the present invention (6) provides a semiconductor nanoparticle composite of any one of (2) to (5) characterized by the mass ratio (ligand / semiconductor nanoparticle) of the ligand and the semiconductor nanoparticle being 0.40 or higher.

[0032] In addition, the present invention (7) provides a semiconductor nanoparticle composite of (1) characterized in that the molecular weight of the mercapto fatty acid ester represented by the general formula (1) is less than 300.

[0033] In addition, the present invention (8) provides a semiconductor nanoparticle composite of (7) characterized in that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 0.40 or less.

[0034] In addition, the present invention (9) provides a semiconductor nanoparticle composite of any one of (1) to (8) characterized by having a content of mercapto fatty acid ester represented by the general formula (1) in the entire ligand of 40 mol% or more.

[0035] In addition, the present invention (10) provides a semiconductor nanoparticle composite of any one of (1) to (8) characterized by having a content of mercapto fatty acid ester represented by the general formula (1) in the entire ligand of 50 mol% or more.

[0036] In addition, the present invention (11) provides a semiconductor nanoparticle composite of any one of (1) to (8) characterized by having a content of mercapto fatty acid ester represented by the general formula (1) in the entire ligand of 60 mol% or more.

[0037] In addition, the present invention (12) provides a semiconductor nanoparticle composite of any one of (1) to (11), characterized in that at least one of the shells is formed of ZnSe.

[0038] In addition, the present invention (13) provides a semiconductor nanoparticle composite of any one of (1) to (12), characterized in that the shell has two or more layers and the outermost layer of the shell is formed of ZnS.

[0039] In addition, the present invention (14) provides a semiconductor nanoparticle composite of any one of (1) to (13), characterized in that the shell is composed of at least a first shell covering the outer surface of the core formed of ZnSe and a second shell covering the outer surface of the first shell formed of ZnS.

[0040] In addition, the present invention (15) provides a semiconductor nanoparticle composite of any one of (1) to (14), characterized in that R2 in the general formula (1) comprises one selected from the group consisting of an oligoethylene glycol group, a polyethylene glycol group, and an alkoxy group.

[0041] In addition, the present invention (16) provides a semiconductor nanoparticle composite of any one of (1) to (15), characterized in that the terminal group of R2 on the side not bonded to -COO- in the general formula (1) is selected from the group consisting of an alkyl group, an alkenyl group and an alkynyl group.

[0042] In addition, the present invention (17) provides a semiconductor nanoparticle complex of any one of (1) to (16), characterized in that the ligand further comprises an aliphatic ligand.

[0043] In addition, the present invention (18) provides a semiconductor nanoparticle complex of (17) characterized in that the aliphatic ligand is one or more selected from the group consisting of aliphatic thiol, aliphatic carboxylic acid and aliphatic phosphine.

[0044] In addition, the present invention (19) provides a semiconductor nanoparticle composite of any one of (1) to (18) characterized by having a quantum efficiency of 80% or more after purification of the semiconductor nanoparticle composite.

[0045] In addition, the present invention (20) provides a semiconductor nanoparticle composite of any one of (1) to (19) characterized in that the full width at half maximum of the emission spectrum of the semiconductor nanoparticle composite is 38 nm or less.

[0046] In addition, the present invention (21) provides a semiconductor nanoparticle composite dispersion in which any one of (1) to (20) is dispersed in an organic dispersion medium.

[0047] In addition, the present invention (22) provides a semiconductor nanoparticle composite composition in which any one of (1) to (20) semiconductor nanoparticle composites is dispersed in a monomer or prepolymer.

[0048] In addition, the present invention (23) provides a semiconductor nanoparticle composite cured film in which any one of (1) to (20) semiconductor nanoparticle composites is dispersed in a polymer matrix.

[0049] In addition, the present invention (24) is a semiconductor nanoparticle composite obtained by contacting a semiconductor nanoparticle having a core containing In and P and one or more shells, and additionally containing a halogen, wherein the molar ratio of the halogen to In in atomic terms is 0.80 to 15.00, with a surface modification compound having a bonding group that bonds to the semiconductor nanoparticle on one side.

[0050] The above surface modification compound is the following general formula (1):

[0051] HS-R1-COO-R2(1)

[0052] It comprises one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group), wherein the SP value of the mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the mercapto fatty acid ester is 700 or lower.

[0053] In addition, the average SP value of the entire surface modification compound is 9.10 to 11.00.

[0054] The purpose is to provide a semiconductor nanoparticle complex characterized by

[0055] In addition, the present invention (25) provides a semiconductor nanoparticle composite of (24) characterized in that the surface modification compound further comprises a surface modification compound containing an aliphatic group having a bonding group that binds to the semiconductor nanoparticle on one end and an aliphatic group on the other end.

[0056] In addition, the range indicated by “~” in this document shall be the range including the numbers indicated at both ends. Effects of the invention

[0057] According to the present invention, a semiconductor nanoparticle composite capable of being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles can be provided. Furthermore, according to the present invention, in addition to being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles, a semiconductor nanoparticle composite capable of being useful for applications requiring high heat resistance can be provided. Furthermore, according to the present invention, in addition to being dispersed in a polar dispersion medium at a high mass fraction while maintaining the high fluorescence quantum efficiency (QY) of the semiconductor nanoparticles, a semiconductor nanoparticle composite capable of being useful for applications requiring low viscosity of the dispersion liquid when dispersed in the dispersion medium can be provided. Brief explanation of the drawing

[0058] Figure 1 is a schematic diagram illustrating a QD device. Figure 2 is a schematic diagram illustrating a QD device. Specific details for implementing the invention

[0059] (Semiconductor nanoparticle complex)

[0060] The semiconductor nanoparticle composite (A) of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated to the surface of a semiconductor nanoparticle, and

[0061] The semiconductor nanoparticles are core / shell type semiconductor nanoparticles having a core containing In and P and one or more shell layers, and

[0062] The semiconductor nanoparticles further comprise a halogen, and the molar ratio of the halogen to In in the semiconductor nanoparticles is 0.80 to 15.00 in atomic terms, and

[0063] The above ligand is the following general formula (1):

[0064] HS-R1-COO-R2(1)

[0065] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0066] The SP value of the above mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the above mercapto fatty acid ester is 700 or lower, and

[0067] In addition, the average SP value of all the above ligands is 9.10 to 11.00.

[0068] It is a semiconductor nanoparticle composite characterized by

[0069] The semiconductor nanoparticle composite of the present invention is a composite of a semiconductor nanoparticle and a ligand, wherein a ligand is coordinated to the surface of the semiconductor nanoparticle. The semiconductor nanoparticle composite of the present invention is obtained by contacting the semiconductor nanoparticle with the ligand.

[0070] In the present invention, the semiconductor nanoparticle composite is a semiconductor nanoparticle composite having luminescent properties. The semiconductor nanoparticle composite of the present invention is a particle that absorbs light of 340 nm to 480 nm and emits light with a luminescent peak wavelength of 400 nm to 750 nm.

[0071] 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 preferably 35 nm or less. Since the full width at half maximum of the emission spectrum is within the above range, color mixing can be reduced when the semiconductor nanoparticle composite is applied to displays, etc.

[0072] 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. Since the fluorescence quantum efficiency of the semiconductor nanoparticle composite is 80% or higher, color conversion can be performed more efficiently when using semiconductor nanoparticles in applications.

[0073] 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 here, the fluorescence quantum efficiency (QY) and full width at half maximum (FWHM) are calculated from the emission spectrum after re-excitation correction, by subtracting the re-excitation fluorescence emission spectrum corresponding to the amount of fluorescence emission that occurred upon re-excitation. Examples of dispersions include normal hexane, PGMEA, chloroform, etc.

[0074] (Semiconductor nanoparticles)

[0075] The semiconductor nanoparticle constituting the semiconductor nanoparticle composite of the present invention is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers. In the semiconductor nanoparticle, the shell only needs to have at least one layer. Examples of semiconductor nanoparticles include a core / shell type semiconductor nanoparticle consisting of a core and one layer of shell, a core / shell type semiconductor nanoparticle consisting of a core and two layers of shell, and a core / shell type semiconductor nanoparticle consisting of a core and three or more layers of shell. In particular, by having two or more shell layers, the fluorescence quantum efficiency of the semiconductor nanoparticle can be maintained, and it becomes possible to have high fluorescence quantum efficiency as a semiconductor nanoparticle composite. Furthermore, regarding the structure of the semiconductor nanoparticle, the shell may cover at least a portion of the surface of the core, but a structure in which the shell covers the entire surface of the core is preferred, and a structure in which the shell uniformly covers the entire surface of the core is particularly preferred.

[0076] Preferably, the shell comprises a shell having a composition including Zn and Se, and preferably, at least one of the shells is formed of ZnSe. When the semiconductor nanoparticle has two or more shells, it is preferable that the outermost layer is a shell having a composition including Zn and S, and more preferable that it is ZnS.

[0077] In particular, when the shell is formed of at least a first shell that covers the outer surface of the core particle and is formed of ZnSe, and a second shell that covers the outer surface of the first shell and is formed of ZnS, the fluorescence quantum efficiency can be increased.

[0078] 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.

[0079] 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.

[0080] The semiconductor nanoparticles according to the semiconductor nanoparticle composite of the present invention contain a halogen. The molar ratio of the halogen to In in the semiconductor nanoparticles is 0.80 to 15.00 in atomic terms, preferably 1.00 to 15.00. The halogens contained in the semiconductor nanoparticles are preferably F, Cl, and Br. By including the halogen in the semiconductor nanoparticles within the above range, high fluorescence quantum efficiency and a narrow full width at half maximum can be obtained, and furthermore, the formation of aggregates can be suppressed during the synthesis of the semiconductor nanoparticle composite described below. In addition, the effects described above can be further observed by the halogen being present at the interface between the core and the shell of the semiconductor nanoparticles and / or within the shell of the semiconductor nanoparticles.

[0081] Among the semiconductor nanoparticles according to the semiconductor nanoparticle composite of the present invention, the molar ratio of P to In is preferably 0.20 to 0.95 in atomic terms. In addition, the molar ratio of Zn to In is preferably 10.00 to 60.00 in atomic terms.

[0082] The analysis of the elements constituting the semiconductor nanoparticles can be performed using a high-frequency inductively coupled plasma emission analyzer (ICP) or a fluorescence X-ray analyzer (XRF).

[0083] Examples of methods for fabricating semiconductor nanoparticles are disclosed below.

[0084] A core of semiconductor nanoparticles can be formed by heating a precursor mixture obtained by mixing an In precursor, a P precursor, and optionally additives in a solvent. As the solvent, a coordination solvent or a non-coordination solvent is used.

[0085] Examples of solvents include 1-octadecene, hexadecane, squalane, oleylamine, trioctylphosphine, and trioctylphosphine oxide.

[0086] Examples of precursors of In include acetates, carboxylates, and halogens containing In, but are not limited to these.

[0087] 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.

[0088] Semiconductor nanoparticles may include one or more elements other than In and P, provided that the effects of the present invention are not impaired, and in such case, a precursor of said element may be added during core formation. Examples of additives include 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.

[0089] After forming the core of the semiconductor nanoparticles, the luminescence properties of the semiconductor nanoparticles can be enhanced by adding a halide as needed.

[0090] In one embodiment, a precursor solution containing an In precursor and, optionally, a dispersant is added to a solvent and 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.

[0091] 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.

[0092] 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, but it is also thought that some move into the interior of the core particles by diffusion.

[0093] The added shell-forming element is mainly located near the surface of the core particle and serves to protect the semiconductor nanoparticle from external factors. In the core / shell structure of the semiconductor nanoparticle, 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 particle.

[0094] In one embodiment, a Zn precursor and a Se precursor are added to the core particle dispersion described above, 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 heated at 200°C to 400°C, preferably 250°C to 350°C. By doing so, core / shell type semiconductor nanoparticles can be obtained.

[0095] 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.

[0096] 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.

[0097] 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.

[0098] The shell precursors may be mixed in advance and added all at once or in multiple stages, or added separately 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.

[0099] In the present invention, the method for producing semiconductor nanoparticles is not particularly limited, and in addition to the method disclosed above, any method may be adopted, such as the hot injection method, homogeneous solvent method, reverse micelle method, CVD method, etc., which are conventionally practiced.

[0100] (ligand)

[0101] 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.

[0102] 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).

[0103] HS-R1-COO-R2(1)

[0104] In general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group. That is, the mercapto fatty acid ester represented by general formula (1) is a compound in which -SH is bonded to one side of R1 and -COO-R2 is bonded to the other side. In the semiconductor nanoparticle composite of the present invention, the ligand coordinated to the semiconductor nanoparticle may include one type of mercapto fatty acid ester represented by general formula (1), or may include two or more types of mercapto fatty acid esters represented by general formula (1).

[0105] By coordinating a mercapto fatty acid ester represented by general formula (1) to semiconductor nanoparticles, a semiconductor nanoparticle complex with high fluorescence quantum efficiency and a narrow full width at half maximum can be obtained.

[0106] In general formula (1), R1 can be a methylene group (-CH2-), an ethylene group (-CH2CH2-), a propylene group (-CH2CH2CH2-), a methylethylene group (-CH(CH3)-), or a dimethylmethylene group (-C(CH3)2-).

[0107] In general formula (1), R2 is not particularly limited as long as it is a hydrophilic group, and examples include hydrophilic groups including alkyl groups, alkynyl groups, alkenyl groups, alkoxy groups, hydroxyl groups, aldehyde groups, carboxyl groups, amino groups, imino groups, nitro groups, cyano groups, vinyl groups, aryl groups, halogen groups, ketone groups, ether bonds, ester bonds, siloxane bonds, etc. R2 is preferably a hydrophilic group having an oligoethylene glycol group, a polyethylene glycol group, or an alkoxy group, and is particularly preferably an oligoethylene glycol group or a polyethylene glycol group. By R2 being a hydrophilic group comprising any one selected from the group consisting of an oligoethylene glycol group, a polyethylene glycol group, and an alkoxy group, semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent. In addition, in general formula (1), it is preferable that the terminal group of R2 on the side not bonded to -COO- is selected from the group consisting of alkyl groups, alkenyl groups and alkynyl groups. By having the terminal group of R2 on the side not bonded to -COO- be selected from the group consisting of alkyl groups, alkenyl groups and alkynyl groups, the interaction between semiconductor nanoparticle composites is suppressed, and the semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent.

[0108] The molecular weight of the mercapto fatty acid ester represented by general formula (1) is 700 or less. Since the molecular weight of the mercapto fatty acid ester represented by general formula (1) is 700 or less, it becomes possible to disperse semiconductor nanoparticles at a high concentration in a polar solvent.

[0109] In addition, in the present invention, the molecular weight of the mercapto fatty acid ester represented by general formula (1) refers to the average molecular weight of the mercapto fatty acid ester represented by general formula (1). The average molecular weight of the mercapto fatty acid ester represented by general formula (1) is measured using the GPC method (gel penetration chromatography), and the number average of the obtained values ​​is used as the average molecular weight (number average molecular weight Mn).

[0110] In addition, the SP value of the mercapto fatty acid ester represented by general formula (1) is 9.20 or higher, preferably 9.20 to 12.00. Since the SP value is within the above range, it becomes possible to disperse semiconductor nanoparticles in a polar solvent. Here, the SP value is determined by calculating it using the Y-MB method. In the present invention, when two or more types of mercapto fatty acid esters represented by general formula (1) are used as ligands, the SP value of each mercapto fatty acid ester is multiplied by the volume fraction of each mercapto fatty acid ester, and then the sum of all the values ​​is taken as the SP value of the mercapto fatty acid ester. For example, when a mercapto fatty acid ester with SP value A1 is coordinated to a semiconductor nanoparticle in P1 volume%, a mercapto fatty acid ester with SP value A2 is coordinated in P2 volume%, etc., the mercapto fatty acid ester SP value is represented by the following formula (2).

[0111] SP value of mercapto fatty acid ester = Σ(Ai × Pi / 100) (2)

[0112] In the semiconductor nanoparticle composite of the present invention, as a ligand, a ligand other than a mercapto fatty acid ester represented by general formula (1) may be included. As for such a ligand other than a mercapto fatty acid ester represented by general formula (1), any compound having a bonding group on one side that coordinates to the semiconductor nanoparticle is not particularly limited and can be used as a compound that coordinates to the semiconductor nanoparticle. Furthermore, it is sufficient if the average SP value of the entire ligand can be adjusted to 9.20 to 11.00, preferably 9.20 to 10.00, by combining it with a mercapto fatty acid ester represented by general formula (1).

[0113] The SP value of the ligand other than the mercapto fatty acid ester represented by general formula (1) is not particularly limited, but is preferably 7.50 to 15.00, and particularly preferably 7.50 to 15.00.

[0114] The average SP value of all ligands coordinated to the semiconductor nanoparticle is 9.20 to 11.00, preferably 9.20 to 10.00. Since the average SP value of all ligands coordinated to the semiconductor nanoparticle is within the above range, it becomes possible to disperse the semiconductor nanoparticle in a polar solvent. The SP value of the ligand can be calculated from the structural formula using the Y-MB method. In cases where there are multiple types of ligands coordinated to the semiconductor nanoparticle, 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 ligand. For example, when ligands with SP value A1 are coordinated to the semiconductor nanoparticle in P1 volume%, ligands with SP value A2 are coordinated in P2 volume%, etc., the average SP value of all ligands is expressed by the following equation (3).

[0115] The average SP value of all ligands = Σ(Ai×Pi / 100) (3)

[0116] As a ligand other than the mercapto fatty acid ester represented by general formula (1), an aliphatic ligand is preferred. By including an aliphatic ligand as a ligand, semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent. Additionally, dispersion is possible in organic solvents with a wider range of SP values. Furthermore, when applied to the composition and dispersion solution described later, it is possible to broaden the options for the dispersion medium.

[0117] Examples of aliphatic ligands include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, aliphatic amines, etc., and one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines are preferred based on the strength of the coordination force with semiconductor nanoparticles. In addition, the aliphatic group of the aliphatic ligand may include substituents or heteroatoms.

[0118] The content of the mercapto fatty acid ester represented by general formula (1) in the total ligand is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more. By setting the content of the mercapto fatty acid ester represented by general formula (1) in the total ligand to the above range, semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent and quantum efficiency can also be increased.

[0119] The semiconductor nanoparticle complex (A) of the present invention may be described in the following first form. The first form of the semiconductor nanoparticle complex (A) of the present invention is a semiconductor nanoparticle complex in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) among the semiconductor nanoparticle complex (A) of the present invention is 300 or more and 700 or less, preferably 300 or more and 600 or less.

[0120] That is, the first form of the semiconductor nanoparticle composite (A) of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated on the surface of a semiconductor nanoparticle,

[0121] The semiconductor nanoparticles are core / shell type semiconductor nanoparticles having a core containing In and P and one or more shell layers, and

[0122] The semiconductor nanoparticles further comprise a halogen, and in the semiconductor nanoparticles, the molar ratio of the halogen to In on an atomic basis is 0.80 to 15.00, and

[0123] The above ligand is the following general formula (1):

[0124] HS-R1-COO-R2(1)

[0125] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0126] The SP value of the mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the mercapto fatty acid ester is 300 or higher and 700 or lower, preferably 300 or higher and 600 or lower, and

[0127] In addition, the average SP value of all the above ligands is 9.10 to 11.00.

[0128] The semiconductor nanoparticle composite is characterized by the following: The molecular weight of the mercapto fatty acid ester represented by general formula (1) is within the above range, thereby ensuring sufficient steric hindrance for the semiconductor nanoparticles to be dispersed in an organic solvent, making it possible to disperse them at a higher concentration, and also improving the heat resistance of the semiconductor nanoparticle composite. Furthermore, in the present invention, heat resistance means that when the semiconductor nanoparticle composite is heat-treated at a certain temperature, it is possible to redisperse it in the solvent in which it was dispersed before the heat treatment even after the heat treatment.

[0129] As one of the embodiments for evaluating heat resistance, the semiconductor nanoparticle composite is treated at 180°C for 1 hour in an atmospheric environment, and then determined by whether the semiconductor nanoparticle composite is redispersed in both solvents. In semiconductor nanoparticle composites that do not have sufficient heat resistance, the dispersibility into both solvents after heating is significantly reduced due to denaturation or detachment of ligands.

[0130] In the first embodiment of the semiconductor nanoparticle composite (A) of the present invention, the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is preferably 1.00 or less, and more preferably 0.70 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 at a high concentration in a polar solvent while maintaining the heat resistance of the semiconductor nanoparticle composite.

[0131] In addition, in the first embodiment of the semiconductor nanoparticle composite (A) of the present invention, it is preferable that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 0.40 or higher. 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 at a high concentration in a polar solvent while maintaining the heat resistance of the semiconductor nanoparticle composite.

[0132] The following second form may be cited as the semiconductor nanoparticle complex (A) of the present invention. The second form of the semiconductor nanoparticle complex (A) of the present invention is a semiconductor nanoparticle complex in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) among the semiconductor nanoparticle complex (A) of the present invention is less than 300.

[0133] That is, the second form of the semiconductor nanoparticle composite (A) of the present invention is a semiconductor nanoparticle composite in which a ligand is coordinated on the surface of the semiconductor nanoparticle,

[0134] The semiconductor nanoparticles are core / shell type semiconductor nanoparticles having a core containing In and P and one or more shell layers, and

[0135] The semiconductor nanoparticles further comprise a halogen, and in the semiconductor nanoparticles, the molar ratio of the halogen to In on an atomic basis is 0.80 to 15.00, and

[0136] The above ligand is the following general formula (1):

[0137] HS-R1-COO-R2(1)

[0138] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0139] The SP value of the mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the mercapto fatty acid ester is less than 300, preferably 100 or higher and less than 300, and

[0140] In addition, the average SP value of all the above ligands is 9.10 to 11.00.

[0141] The semiconductor nanoparticle composite is characterized by the above. Since the molecular weight of the mercapto fatty acid ester represented by general formula (1) is within the above range, the viscosity of the dispersion can be lowered even when the semiconductor nanoparticle composite is dispersed at a high mass fraction. Furthermore, in the present invention, the low viscosity of the dispersion when the semiconductor nanoparticle composite is dispersed at a high mass fraction means that when the semiconductor nanoparticle composite is dispersed in isobornyl acrylate at a mass ratio of 30.0 mass% of the semiconductor nanoparticles, the viscosity at 25°C is 30 cp or less.

[0142] In the second embodiment of the semiconductor nanoparticle composite (A) of the present invention, it is preferable that the mass ratio of the ligand to the semiconductor nanoparticle (ligand / semiconductor nanoparticle) is 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 at a high concentration in a polar solvent while suppressing the increase in viscosity of the dispersion in which the semiconductor nanoparticle composite is dispersed.

[0143] The semiconductor nanoparticle composite (B) of the present invention is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, additionally containing a halogen, wherein the molar ratio of the halogen to In in atomic terms is 0.80 to 15.00, and is obtained by contacting a semiconductor nanoparticle having a bonding group that bonds to the semiconductor nanoparticle on one side with the semiconductor nanoparticle.

[0144] The above surface modification compound is the following general formula (1):

[0145] HS-R1-COO-R2(1)

[0146] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0147] The SP value of the above mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the above mercapto fatty acid ester is 700 or lower, and

[0148] In addition, the average SP value of the entire surface modification compound is 9.10 to 11.00.

[0149] It is a semiconductor nanoparticle composite characterized by

[0150] The semiconductor nanoparticle composite (B) of the present invention is a semiconductor nanoparticle composite obtained by contacting a semiconductor nanoparticle with a surface modification compound having a bonding group on one side that binds to the semiconductor nanoparticle. The method of contacting the semiconductor nanoparticle with the surface modification compound is not particularly limited, but, for example, a method of adding the surface modification compound to a dispersion of semiconductor nanoparticles may be used. Depending on the bonding strength of the surface modification compound to the semiconductor nanoparticle, heating or stirring may be involved when adding the surface modification compound.

[0151] The semiconductor nanoparticles according to the semiconductor nanoparticle complex (B) of the present invention are identical to the semiconductor nanoparticles according to the semiconductor nanoparticle complex (A) of the present invention.

[0152] Examples of bonding groups according to a surface modification compound having a bonding group that binds to a semiconductor nanoparticle on one side include thiol groups, carboxylic acid groups, phosphine groups, phosphine oxide groups, amine groups, etc. Examples of surface modification compounds having a bonding group that binds to a semiconductor nanoparticle on one side include ligands according to the semiconductor nanoparticle complex (A) of the present invention.

[0153] The semiconductor nanoparticle composite (B) of the present invention comprises a mercapto fatty acid ester represented by the following general formula (1) as a surface modification compound having a bonding group that binds to the semiconductor nanoparticle on one side.

[0154] HS-R1-COO-R2(1)

[0155] In the semiconductor nanoparticle complex (B) of the present invention, the mercapto fatty acid ester represented by general formula (1), which is a surface modification compound, is the same as the mercapto fatty acid ester represented by general formula (1) in the semiconductor nanoparticle complex (A) of the present invention.

[0156] In the semiconductor nanoparticle composite (B) of the present invention, by using a mercapto fatty acid ester represented by general formula (1) as a surface modification compound, a semiconductor nanoparticle composite with high fluorescence quantum efficiency and a narrow full width at half maximum can be obtained.

[0157] In the semiconductor nanoparticle composite (B) of the present invention, the molecular weight of the mercapto fatty acid ester represented by general formula (1) is 700 or less. Since the molecular weight of the mercapto fatty acid ester represented by general formula (1) is 700 or less, it becomes possible to disperse the semiconductor nanoparticles at a high concentration in a polar solvent.

[0158] In the semiconductor nanoparticle composite (B) of the present invention, the SP value of the mercapto fatty acid ester represented by general formula (1) is 9.20 or higher, preferably 9.20 to 12.00. By having the SP value in the above range, it becomes possible to disperse the semiconductor nanoparticles in a polar solvent.

[0159] In the semiconductor nanoparticle composite (B) of the present invention, a surface modification compound other than a mercapto fatty acid ester represented by general formula (1) may be included as a surface modification compound having a bonding group that binds to the semiconductor nanoparticle on one side. As for the surface modification compound other than the mercapto fatty acid ester represented by general formula (1), any compound having a bonding group that binds to the semiconductor nanoparticle on one side is not particularly limited and can be used as a surface modification compound for semiconductor nanoparticles. Furthermore, it is sufficient if the average SP value of the entire surface modification compound can be adjusted to 9.20 to 11.00, preferably 9.20 to 10.00, when used in combination with the mercapto fatty acid ester represented by general formula (1).

[0160] The SP value of a surface modification compound other than a mercapto fatty acid ester represented by general formula (1) is not particularly limited, but is preferably 7.00 to 15.00, and particularly preferably 7.50 to 15.00.

[0161] The average SP value of the entire surface modification compound having a bonding group that binds to semiconductor nanoparticles on one side is 9.20 to 11.00, preferably 9.20 to 10.00. By having the average SP value of the entire surface modification compound having a bonding group that binds to semiconductor nanoparticles on one side within the above range, it becomes possible to disperse semiconductor nanoparticles in a polar solvent.

[0162] As a surface modification compound other than the mercapto fatty acid ester represented by general formula (1), an aliphatic group-containing surface modification compound having a bonding group that binds to semiconductor nanoparticles on one end and an aliphatic group on the other end is preferred. By including an aliphatic group-containing surface modification compound as a surface modification compound, semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent. In addition, dispersion is possible in organic solvents with a wider range of SP values. Furthermore, when applied to the composition and dispersion liquid described later, it is possible to broaden the selection of dispersion media.

[0163] Examples of aliphatic group-containing surface modification compounds include aliphatic thiols, aliphatic carboxylic acids, aliphatic phosphines, aliphatic phosphine oxides, aliphatic amines, etc., and based on the strength of the coordination force with semiconductor nanoparticles, one or more selected from the group consisting of aliphatic thiols, aliphatic carboxylic acids, and aliphatic phosphines are preferred. In addition, the aliphatic group of the aliphatic group-containing surface modification compound may include substituents or heteroatoms.

[0164] The content of the mercapto fatty acid ester represented by general formula (1) in the entire surface modification compound having a bonding group that binds to semiconductor nanoparticles on one side is preferably 40 mol% or more, more preferably 50 mol% or more, and even more preferably 60 mol% or more. By setting the content of the mercapto fatty acid ester represented by general formula (1) in the entire surface modification compound having a bonding group that binds to semiconductor nanoparticles on one side to the above range, semiconductor nanoparticles can be dispersed at a high concentration in a polar solvent and quantum efficiency can also be increased.

[0165] The semiconductor nanoparticle complex (B) of the present invention may be described in the following first form. The first form of the semiconductor nanoparticle complex (B) of the present invention is a semiconductor nanoparticle complex in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) among the semiconductor nanoparticle complex (B) of the present invention is 300 or more and 700 or less, preferably 300 or more and 600 or less.

[0166] That is, the first form of the semiconductor nanoparticle composite (B) of the present invention is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, additionally comprising a halogen, wherein the molar ratio of the halogen to In in atomic terms is 0.80 to 15.00, and the semiconductor nanoparticle is obtained by contacting a semiconductor nanoparticle having a bonding group that bonds to the semiconductor nanoparticle on one side with the semiconductor nanoparticle.

[0167] The above surface modification compound is the following general formula (1):

[0168] HS-R1-COO-R2(1)

[0169] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0170] The SP value of the mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the mercapto fatty acid ester is 300 or higher and 700 or lower, preferably 300 or higher and 600 or lower, and

[0171] In addition, the average SP value of the entire surface modification compound is 9.10 to 11.00.

[0172] It is a semiconductor nanoparticle composite characterized by the above. Since the molecular weight of the mercapto fatty acid ester represented by general formula (1) is within the above range, sufficient steric hindrance is secured for the semiconductor nanoparticles to be dispersed in an organic solvent, making it possible to disperse them at a higher concentration, and also improving the heat resistance of the semiconductor nanoparticle composite.

[0173] In the first embodiment of the semiconductor nanoparticle composite (B) of the present invention, the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) is preferably 1.00 or less, and more preferably 0.70 or less. By having the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) within the above range, it becomes possible to disperse the semiconductor nanoparticle at a high concentration in a polar solvent while maintaining the heat resistance of the semiconductor nanoparticle composite.

[0174] In addition, in the first embodiment of the semiconductor nanoparticle composite (B) of the present invention, it is preferable that the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) is 0.40 or higher. By having the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) within the above range, it becomes possible to disperse the semiconductor nanoparticle at a high concentration in a polar solvent while maintaining the heat resistance of the semiconductor nanoparticle composite.

[0175] The following second form may be cited as the semiconductor nanoparticle complex (B) of the present invention. The second form of the semiconductor nanoparticle complex (B) of the present invention is a semiconductor nanoparticle complex in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) among the semiconductor nanoparticle complex (B) of the present invention is less than 300.

[0176] That is, the second form of the semiconductor nanoparticle composite (B) of the present invention is a semiconductor nanoparticle composite obtained by contacting a semiconductor nanoparticle, which is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, additionally containing a halogen, wherein the molar ratio of the halogen to In in atomic terms is 0.80 to 15.00, with a surface modification compound having a bonding group that bonds to the semiconductor nanoparticle on one side.

[0177] The above surface modification compound is the following general formula (1):

[0178] HS-R1-COO-R2(1)

[0179] It includes one or more mercapto fatty acid esters represented by (in general formula (1), R1 represents an alkylene group having 1 to 3 carbon atoms, and R2 represents a hydrophilic group),

[0180] The SP value of the mercapto fatty acid ester is 9.20 or higher, and the molecular weight of the mercapto fatty acid ester is less than 300, preferably 100 or higher and less than 300, and

[0181] In addition, the average SP value of the entire surface modification compound is 9.10 to 11.00.

[0182] It is a semiconductor nanoparticle composite characterized by the above. By having the molecular weight of the mercapto fatty acid ester represented by general formula (1) within the above range, the viscosity of the dispersion in which the semiconductor nanoparticle composite is dispersed can be lowered.

[0183] In the second embodiment of the semiconductor nanoparticle composite (B) of the present invention, it is preferable that the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) is 0.40 or less. By having the mass ratio of the surface modification compound to the semiconductor nanoparticle (surface modification compound / semiconductor nanoparticle) within the above range, it becomes possible to disperse the semiconductor nanoparticle at a high concentration in a polar solvent while suppressing the increase in viscosity of the dispersion in which the semiconductor nanoparticle composite is dispersed.

[0184] (Regarding tablets)

[0185] The semiconductor nanoparticle composite of the present invention can be separated and purified from the reaction solution as needed. As a purification method, a method is used in which the semiconductor nanoparticle composite is aggregated using a non-solvent and then separated.

[0186] In one embodiment, a semiconductor nanoparticle complex can be precipitated from a dispersion by adding a polarity-changing solvent such as acetone. The precipitated semiconductor nanoparticle complex can be recovered by filtration or centrifugation, while the supernatant containing unreacted starting materials and other impurities can be discarded or reused. Subsequently, the precipitated semiconductor nanoparticle complex 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.

[0187] In the present invention, as a method for purifying a semiconductor nanoparticle composite, in addition to the method disclosed 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.

[0188] (Semiconductor nanoparticle complex dispersion)

[0189] The semiconductor nanoparticle composite of the present invention can be dispersed in a polar 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 visible 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.

[0190] The semiconductor nanoparticle composite of the present invention is dispersed in an organic dispersion medium with an SP value of 8.50 or higher, an organic dispersion medium with an SP value of 9.00 or higher, or an organic dispersion medium with an SP value of 10.00 or higher, to form a semiconductor nanoparticle composite dispersion.

[0191] The SP value here is a value calculated from Hansen solubility parameters in the same way as the method for determining the SP value of the polar ligand above. Hansen solubility parameters can be determined using values ​​from a handbook, for example, “Hansen Solubility Parameters: A User’s Handbook”, 2nd edition, CMHansen (2007), or the Practice (HSPiP) program (2nd edition) provided by Hanson and Abbot et al. For organic dispersion media not listed in the handbook, they can be determined by calculation using the Y-MB method.

[0192] In the present invention, as an organic dispersion medium of the semiconductor nanoparticle composite dispersion of the present invention, alcohols such as methanol, ethanol, isopropyl alcohol, and normal propyl alcohol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclopentanone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, isopropyl acetate, normal propyl acetate, normal butyl acetate, and ethyl lactate; ethers such as diethyl ether, dipropyl ether, dibutyl ether, and tetrahydrofuran; ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monomethyl ether, ethylene glycol diethyl ether, diethylene glycol dimethyl ether, propylene glycol monomethyl ether (PGME), propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, propylene glycol dimethyl ether, and dipropylene glycol dimethyl ether. Glycol ethers such as propylene glycol diethyl ether and dipropylene glycol diethyl ether, and glycol ether esters such as ethylene glycol acetate, ethylene glycol monoethyl ether acetate, diethylene glycol monoethyl ether acetate, diethylene glycol monobutyl ether acetate, propylene glycol monomethyl ether acetate (PGMEA), and dipropylene glycol monoethyl ether acetate are selected. By dispersing the semiconductor nanoparticle composite of the present invention in these organic dispersion media, the semiconductor nanoparticle composite can be used while maintaining its dispersibility when applied to dispersion into a cured film or resin described later.

[0193] In particular, in the semiconductor nanoparticle composite of the present invention, it is possible to select polar organic dispersion media such as alcohols, glycol ethers, and glycol ether esters as organic dispersion media. By dispersing the semiconductor nanoparticle composite of the present invention in these organic dispersion media, it is possible to use the semiconductor nanoparticle composite while maintaining its dispersibility when applied to dispersion into a cured film or resin described later. In particular, PGMEA and PGME are generally used as dilution solvents in the field of photoresist, and if the semiconductor nanoparticle composite can be dispersed in PGMEA and PGME, the semiconductor nanoparticle composite can be widely applied in the field of photoresist.

[0194] By adopting the configuration described above, the semiconductor nanoparticle composite of the present invention can be dispersed in an organic dispersion medium at a high mass fraction, and as a result, the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite dispersion can be 20 mass% or more, 30 mass% or more, and 35 mass% or more.

[0195] In addition, in the present invention, a monomer may be selected as the 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 individually 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.

[0196] In addition, in the present invention, a prepolymer may be selected as the 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.

[0197] (Semiconductor nanoparticle complex composition)

[0198] 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 of the present invention. 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. The monomer or prepolymer is not particularly limited, but may include radical polymerizable compounds containing ethylenically unsaturated bonds, siloxane compounds, epoxy compounds, isocyanate compounds, and phenol derivatives. As a monomer, for example, the monomer used as the dispersion medium described above may be cited. Also, as a prepolymer, the prepolymer used as the dispersion medium described above may be cited.

[0199] In addition, the semiconductor nanoparticle composite composition of the present invention may include a crosslinking agent. Depending on the type of monomer in the semiconductor nanoparticle composite composition of the present invention, the crosslinking agent is selected from polyfunctional (meth)acrylates, polyfunctional silane compounds, polyfunctional amines, polyfunctional carboxylic acids, polyfunctional thiols, polyfunctional alcohols, and polyfunctional isocyanates.

[0200] 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.

[0201] 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.

[0202] In addition, to improve the optical properties of the semiconductor nanoparticle composite composition of the present invention or the cured film of the semiconductor nanoparticle composite of the present invention described below, the semiconductor nanoparticle composite composition 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 thereof 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 in the semiconductor nanoparticle composite composition of the present invention is preferably 2 mass% to 30 mass% with respect to the composition, and is more preferable to be 5 mass% to 20 mass% from the perspective of maintaining the patternability of the composition.

[0203] By the composition of the semiconductor nanoparticle composite of the present invention, the mass fraction of semiconductor nanoparticles in the semiconductor nanoparticle composite composition of the present invention 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.

[0204] When the semiconductor nanoparticle composite composition of the present invention is made into a 10 μm film, it is preferable that the absorbance for light of a wavelength of 450 nm from the normal direction of the film is 1.0 or higher, more preferable that it is 1.3 or higher, and more preferable that it is 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.

[0205] (Diluted composition)

[0206] The diluted composition is formed by diluting the semiconductor nanoparticle composite composition of the present invention described above with an organic solvent.

[0207] The organic solvent used to dilute the semiconductor nanoparticle composite composition is not particularly limited and may include, for example, aliphatic hydrocarbons such as pentane, hexane, cyclohexane, isohexane, heptane, octane, and petroleum ethers; alcohols, ketones, esters, glycol ethers, glycol ether esters; aromatic hydrocarbons such as benzene, toluene, xylene, and mineral spirits; and alkyl halides such as dichloromethane and chloroform. Among these, glycol ethers and glycol ether esters are preferred from the perspective of wide solubility in resins and film uniformity during coating.

[0208] (Semiconductor nanoparticle composite cured film)

[0209] The semiconductor nanoparticle composite cured film of the present invention refers to a film containing the semiconductor nanoparticle composite of the present invention that is cured. The semiconductor nanoparticle composite cured film of the present invention is obtained by curing the semiconductor nanoparticle composite composition or diluted composition described above into a film shape.

[0210] The semiconductor nanoparticle composite cured film of the present invention comprises semiconductor nanoparticles according to the semiconductor nanoparticle composite of the present invention, ligands coordinated to the surface of the semiconductor nanoparticles, and a polymer matrix. In other words, the semiconductor nanoparticle composite cured film of the present invention is a cured film in which the semiconductor nanoparticle composite of the present invention is dispersed in a polymer matrix.

[0211] As a polymer matrix, 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., although not particularly limited. In addition, a cured semiconductor nanoparticle composite film of the present invention may be obtained by curing the semiconductor nanoparticle composite composition of the present invention described above. The cured semiconductor nanoparticle composite film of the present invention may additionally include a crosslinking agent.

[0212] The method for curing the film is not particularly limited, but the film can be cured by a curing method suitable for the composition constituting the film, such as heat treatment or UV treatment.

[0213] It is preferable that the semiconductor nanoparticles and the ligands coordinated to the surface of the semiconductor nanoparticles, included in the semiconductor nanoparticle composite cured film of the present invention, constitute the semiconductor nanoparticle composite of the present invention as 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. The mass fraction of the semiconductor nanoparticles in the semiconductor nanoparticle composite cured film is preferably 30 mass% or more, and more preferably 40 mass% or more. However, if it is 70 mass% or more, the composition constituting the film becomes insufficient, and it becomes difficult to cured and form the film.

[0214] Since the semiconductor nanoparticle composite cured film of the present invention contains semiconductor nanoparticle composites in a high mass fraction, the absorbance of the semiconductor nanoparticle composite cured film can be increased. When the semiconductor nanoparticle composite cured film of the present invention has a thickness of 10 μm, for light of a wavelength of 450 nm from the normal direction of the semiconductor nanoparticle composite cured film, the absorbance is preferably 1.0 or higher, more preferably 1.3 or higher, and even more preferably 1.5 or higher.

[0215] 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 of the present invention is preferably 70% or higher, and more preferably 80% or higher.

[0216] For miniaturization of a device to which the semiconductor nanoparticle composite cured film of the present invention 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.

[0217] (Semiconductor nanoparticle composite patterning film and display device)

[0218] A semiconductor nanoparticle composite patterning film can be obtained by patterning the semiconductor nanoparticle composite composition or dilution composition described above 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.

[0219] 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.

[0220] Please understand that the configurations and / or methods described in this specification are presented as examples and that, as numerous variations are possible, these specific examples or embodiments should not be construed as limiting. A specific sequence or method described in this specification 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 methods described above may be changed.

[0221] The subject matter disclosed herein includes all novel and non-obvious combinations and secondary combinations of various methods, systems and configurations disclosed herein, and other features, functions, acts and / or qualities, and all equivalents thereof.

[0222] Examples

[0223] The present invention will be specifically explained below through examples and comparative examples, but the present invention is not limited thereto.

[0224] (ligand)

[0225] The ligand groups used in the examples and comparative examples were prepared as follows. In addition, PEG refers to a polyethylene glycol chain, and "-(CH2CH2O) n It is a structure indicated as "-CH3".

[0226] <Production of Ligand Groups>

[0227] (Method for preparing 1,1-dimethyl-3-oxobutyl mercaptopropionic acid)

[0228] 4.2 g of 3-mercaptopropionic acid (40 mmol), 4.7 g of diacetone alcohol (40 mmol), 5.4 g of 1-hydroxybenzotriazole (40 mmol), 100 mL of methylene chloride, and 7.7 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (40 mmol) were mixed in a flask under a nitrogen atmosphere. After reacting the solution at room temperature for 60 minutes, the reaction solution was transferred to a separatory lot 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 (mercaptopropionic acid 1,1-dimethyl-3-oxobutyl).

[0229] (Method for preparing thioglycolic acid PEG ester (molecular weight 470))

[0230] 3.7 g of thioglycolic acid (40 mmol), 19.2 g of methoxy PEG-OH (molecular weight 400, 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 to obtain the target ligand (thioglycolic acid PEG ester, molecular weight 470).

[0231] (Method for preparing thioglycolic acid PEG ester (molecular weight 760))

[0232] By changing methoxy PEG-OH (molecular weight 400, 48 mmol) to methoxy PEG-OH (molecular weight 690, 48 mmol) and preparing it in the same way as above, a thioglycolic acid PEG ester with a molecular weight of 760 was obtained.

[0233] (Method for preparing 3-mercaptopropionic acid PEG ester (molecular weight 550))

[0234] 4.2 g of 3-mercaptopropionic acid (40 mmol), 21.6 g of methoxyPEG-OH (molecular weight 450, 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 to obtain the target ligand (3-mercaptopropionic acid PEG ester, molecular weight 550).

[0235] (Method for preparing 3-mercaptopropionic acid PEG ester (molecular weight 640))

[0236] By changing methoxy PEG-OH (molecular weight 450, 48 mmol) to methoxy PEG-OH (molecular weight 550, 48 mmol) and preparing it in the same way as above, a 3-mercaptopropionic acid PEG ester with a molecular weight of 760 was obtained.

[0237] (Method for adjusting 3-mercaptopropionic acid 2-[2-(2-acetoxyethoxy)ethoxy]ethyl)

[0238] 2.1 g of 3-mercaptopropionic acid (20 mmol), 1.2 g of acetic acid (20 mmol), 7.2 g of triethylene glycol (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 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 2-[2-(2-acetoxyethoxy)ethoxy]ethyl).

[0239] (Method for preparing 6-mercaptohexanoic acid PEG ester)

[0240] 5.9 g of 6-mercaptohexanoic acid (40 mmol), 19.2 g of methoxy PEG-OH (molecular weight 400, 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 to obtain the target ligand (6-mercaptohexanoic acid PEG ester, molecular weight 530).

[0241] (Method for adjusting 3-mercaptopropionic acid 2-[2-(2-levulinoxyethoxy)ethoxy]ethyl)

[0242] 2.1 g of 3-mercaptopropionic acid (20 mmol), 2.3 g of levulinic acid (20 mmol), 6.0 g of triethylene glycol (40 mmol), 5.4 g of 1-hydroxybenzotriazole (40 mmol), 100 mL of methylene chloride, and 7.7 g of 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (40 mmol) were mixed in a flask under a nitrogen atmosphere. After reacting the solution at room temperature for 60 minutes, the reaction solution was transferred to a separatory lot 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 (2-[2-(2-levulinoxyethoxy)ethoxy]ethyl 3-mercaptopropionic acid).

[0243] (Method for preparing 3-mercaptopropionic acid 2-[2-[2-(2-hexyloxyethoxy)ethoxy]ethoxy]ethyl)

[0244] 4.2 g of 3-mercaptopropionic acid (40 mmol), 13.4 g of tetraethylene glycol monohexyl ether (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 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 2-[2-[2-(2-hexyloxyethoxy)ethoxy]ethoxy]ethyl).

[0245] [Example 1]

[0246] InP-based semiconductor nanoparticle composites were fabricated according to the following method.

[0247] (Production of core particles)

[0248] 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 then heated to 25°C under a nitrogen atmosphere, tris(trimethylsilyl)phosphine (0.2 mmol) was added, and the mixture was heated to about 300°C and reacted for 10 minutes. The reaction solution was cooled to 25°C, octanoic acid chloride (1.1 mmol) was added, heated to about 250°C for 30 minutes, and then cooled to 25°C to obtain a dispersion of InP-based semiconductor nanoparticles.

[0249] (Precursor for shell formation)

[0250] In the production of the shell, the following precursors were first prepared.

[0251] (Preparation of Zn precursor solution)

[0252] 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.

[0253] (Preparation of Se precursor (trioctylphosphine selenide))

[0254] 22 mmol of selenium powder and 10 mL of trioctylphosphine were mixed under nitrogen and stirred until all dissolved to obtain [Se]=2.2 M selenized trioctylphosphine.

[0255] (Preparation of S precursor (trioctylphosphine sulfide))

[0256] 22 mmol of sulfur powder and 10 mL of trioctylphosphine were mixed in nitrogen and stirred until all dissolved to obtain [S]=2.2 M trioctylphosphine sulfide.

[0257] Using each precursor obtained as described above, a shell was formed on the surface of the InP-based semiconductor nanoparticle (core) as follows.

[0258] (Formation of shells)

[0259] 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 InP-based semiconductor nanoparticles. Additionally, 4.0 mL of a Zn precursor solution and 1.8 mL of trioctylphosphine sulfide were added, and the temperature was raised to 280°C and reacted for 1 hour to form a ZnS shell.

[0260] As a result of observing the obtained semiconductor nanoparticles by STEM-EDS, it was confirmed that they have a core / shell structure.

[0261] Dehydrated acetone was added to a solution in which semiconductor nanoparticles with a core / shell structure obtained by synthesis were dispersed, causing the semiconductor nanoparticles to aggregate. Subsequently, after centrifugation (4000 rpm, 10 minutes), the supernatant was removed, and the semiconductor nanoparticles were redispersed in hexane. This process was repeated to obtain purified semiconductor nanoparticles.

[0262] (Composition Analysis)

[0263] Elemental analysis of semiconductor nanoparticles was performed using an inductively coupled plasma emission analyzer (ICP) and an X-ray fluorescence analyzer (XRF). For ICP measurements, purified semiconductor nanoparticles were dissolved in acetic acid, heated, and then diluted with water. The samples were then measured using the calibration curve method with an ICP emission analyzer (ICPS-8100, manufactured by Shimadzu Corporation). For XRF measurements, the dispersion was impregnated onto filter paper, placed in a sample holder, and quantitative analysis was performed using an X-ray fluorescence analyzer (ZSX100e, manufactured by Rigaku Corporation). The molar ratio of halogen to In in the semiconductor nanoparticles is listed in Table 1.

[0264] (Fabrication of semiconductor nanoparticle complexes)

[0265] 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, 3.6 g of thioglycolic acid PEG ester (molecular weight 470) as a mercapto fatty acid ester and 0.4 g of dodecanethiol as a non-polar 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, resulting in separation 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.

[0266] 5.0 mL of acetone was added to the obtained semiconductor nanoparticle composite to prepare a dispersion. 50 mL of n-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 to recover the precipitate. This operation was repeated several times to obtain a purified semiconductor nanoparticle composite.

[0267] <Analysis>

[0268] (Measurement of the molecular weight of the ligand)

[0269] The molecular weight of the ligand was measured using the GPC method with a liquid chromatograph (LC-20: Shimadzu Corporation). First, the ligand was dissolved in THF (tetrahydrofuran) to obtain an eluent. The eluent was injected into a column (KF-801, KF-803, KF-805: Shodex), and the number average molecular weight was calculated from the obtained molecular weight distribution curve. At this time, the standard material used was polyethylene glycol (Polyethylene glycol READY_CAL SET Mp 102-40,000: Aldrich), which has a conventional average molecular weight.

[0270] (Fluorescence Quantum Efficiency Measurement)

[0271] The optical properties of the semiconductor nanoparticle composite were measured using a fluorescence quantum efficiency measurement system (QE-2100 manufactured by Otsuka Electronics Co., Ltd.). The semiconductor nanoparticle composite obtained by synthesis was dispersed in a dispersion medium, and an emission spectrum was obtained by exposing it to a single light of 450 nm as the excitation light. 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. Propylene glycol monomethyl ether acetate (PGMEA) was used as the dispersion medium. The obtained results are listed in Table 2.

[0272] ( 1 H-NMR measurement)

[0273] For the purified semiconductor nanoparticle complex, the ligands coordinated to the semiconductor nanoparticles were analyzed using a nuclear magnetic resonance (NMR) instrument (JNM-LA400 manufactured by JEOL Ltd.). For all measurements, heavy chloroform was used as the solvent and tetramethylsilane was used as the standard for chemical shifts, 1H-NMR was measured. From the semiconductor nanoparticle composite obtained in 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 of mercapto fatty acid esters to all ligands were calculated. The obtained results are listed in Tables 1 and 3.

[0274] (Thermogravimetric analysis)

[0275] The purified semiconductor nanoparticle composite was heated to 550°C for differential thermal gravimetric 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 from this value, the mass ratio of ligands to semiconductor nanoparticles (ligand / semiconductor nanoparticles) in the semiconductor nanoparticle composite was determined. The obtained results are listed in Tables 1 and 3.

[0276] (Dispersion test)

[0277] 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 20.0 mass%, 30.0 mass%, and 35.0 mass%, respectively, and the dispersion state was checked. In Tables 2 and 4, "○" was indicated for dispersed samples, and "×" was indicated for samples where precipitation or turbidity was observed. In addition, propylene glycol monomethyl ether acetate (PGMEA) was used as the dispersion medium.

[0278] (Filterability test)

[0279] A filtration test was performed on samples for which a dispersion of semiconductor nanoparticle complex PGMEA with a semiconductor nanoparticle concentration of 20.0 mass% could be prepared. 1 mL of a 20 mass% semiconductor nanoparticle complex PGMEA solution was weighed into a syringe and filtered using a PTFE syringe filter with a diameter of 0.45 μm (filter diameter 13 mm). In Tables 2 and 4, samples that could be filtered with a single syringe filter were marked with "○", and those that became clogged along the way were marked with "×".

[0280] (Heat resistance test)

[0281] 50 mg of semiconductor nanoparticle composite was weighed into a sample tube and heated at 180°C for 60 minutes under an atmospheric environment. The sample was air-cooled to room temperature, 1 mL of chloroform was added, and the dispersion state was checked. In Tables 2 and 4, "○" was marked for dispersed samples, and "×" was marked for samples where precipitation or turbidity was observed.

[0282] (Measurement of viscosity)

[0283] A semiconductor nanoparticle composite was dispersed in isobornyl acrylate to a semiconductor nanoparticle concentration of 30.0 mass% to prepare a dispersion. Subsequently, the viscosity of the obtained dispersion was measured at 25°C using a TA Instruments AR-2000 rheometer. The measurement was performed at 0.1 s -1 After performing preliminary shearing for 1 minute, 0.1s -1 from 1000s -1 It was performed by varying the shear rate up to 100s. -1 In Tables 2 and 4, cases where the viscosity was 30 cp or less were marked “◎”, cases where it exceeded 30 cp and was 60 cp or less were marked “○”, and cases where it exceeded 60 cp were marked “×”. In addition, a hyphen (-) was indicated for samples for which a 30 mass% semiconductor nanoparticle composite isobornyl acrylate dispersion could not be prepared.

[0284] (Example 2)

[0285] 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 PEG ester (molecular weight 550) was used as the mercapto fatty acid ester and 0.8 g of oleic acid was used as the aliphatic ligand.

[0286] (Example 3)

[0287] 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 thioglycolic acid PEG ester (molecular weight 470) was used as the mercapto fatty acid ester and 0.8 g of 3-mercaptopropionic acid ethylhexyl was used instead of the aliphatic ligand.

[0288] (Example 4)

[0289] 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, 6.4 g of 3-mercaptopropionic acid PEG ester (molecular weight 640) was used as the mercapto fatty acid ester and 0.8 g of dodecanethiol was used as the aliphatic ligand.

[0290] (Example 5)

[0291] 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, 2.8 g of thioglycolic acid PEG ester (molecular weight 470) was used as the mercapto fatty acid ester and 1.2 g of dodecanethiol was used as the aliphatic ligand.

[0292] (Example 6)

[0293] 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, 2.4 g of thioglycolic acid PEG ester (molecular weight 470) was used as the mercapto fatty acid ester and 1.6 g of dodecanethiol was used as the aliphatic ligand.

[0294] (Example 7)

[0295] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 0.45 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.6 g of 3-mercaptopropionic acid PEG ester (molecular weight 550) was used as the mercapto fatty acid ester and 0.4 g of dodecanethiol was used as the aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0296] (Example 8)

[0297] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 2.5 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.8 g of 3-mercaptopropionic acid PEG ester was used as the mercapto fatty acid ester and 0.2 g of dodecanethiol was used as the aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0298] (Example 9)

[0299] 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, 3.6 g of 3-mercaptopropionic acid 2-[2-[2-(2-hexyloxyethoxy)ethoxy]ethoxy]ethyl was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand.

[0300] (Example 10)

[0301] 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, 3.8 g of 3-mercaptopropionic acid 2-[2-(2-levulinoxyethoxy)ethoxy]ethyl was used as a mercapto fatty acid ester and 0.2 g of dodecanethiol was used as an aliphatic ligand.

[0302] (Example 11)

[0303] 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, 3.6 g of 3-mercaptopropionic acid 1,1-dimethyl-3-oxobutyl was used as a mercapto fatty acid ester and 0.4 g of trioctylphosphine was used as an aliphatic ligand.

[0304] (Example 12)

[0305] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 0.45 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.2 g of 3-methoxybutyl 3-mercaptopropionic acid was used as a mercapto fatty acid ester and 0.8 g of dodecanethiol was used as an aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0306] (Example 13)

[0307] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 2.5 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.2 g of 3-mercaptopropionic acid 1,1-dimethyl-3-oxobutyl was used as a mercapto fatty acid ester and 0.8 g of dodecanethiol was used as an aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0308] (Example 14)

[0309] 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, 2.8 g of 3-methoxybutyl 3-mercaptopropionic acid was used as a mercapto fatty acid ester and 1.2 g of dodecanethiol was used as an aliphatic ligand.

[0310] (Example 15)

[0311] 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, 3.8 g of 3-mercaptopropionic acid 2-[2-(2-acetoxyethoxy)ethoxy]ethyl was used as a mercapto fatty acid ester and 0.05 g of dodecanethiol was used as an aliphatic ligand.

[0312] (Example 16)

[0313] 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, 2.8 g of 3-methoxybutyl 3-mercaptopropionic acid was used as the mercapto fatty acid ester and 1.2 g of benzenethiol was used instead of the aliphatic ligand.

[0314] (Example 17)

[0315] In the shell formation reaction, after forming a ZnSe shell, the mixture was cooled to room temperature without adding the Zn precursor solution or trioctylphosphine sulfide. Additionally, in the process of fabricating the semiconductor nanoparticle complex, 3.2 g of 3-mercaptopropionic acid 1,1-dimethyl-3-oxobutyl was used as the mercapto fatty acid ester and 0.8 g of dodecanethiol was used as the aliphatic ligand; otherwise, the semiconductor nanoparticle complex was obtained in the same manner as in Example 1.

[0316] (Comparative Example 1)

[0317] 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, 9.6 g of thioglycolic acid PEG ester (molecular weight 760) was used as the mercapto fatty acid ester and 0.8 g of dodecanethiol was used as the aliphatic ligand.

[0318] (Comparative Example 2)

[0319] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 4.5 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.6 g of thioglycolic acid PEG ester (molecular weight 470) was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0320] (Comparative Example 3)

[0321] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 3.2 g of 6-mercaptohexanoic acid PEG ester was used as the mercapto fatty acid ester and 0.8 g of dodecanethiol was used as the aliphatic ligand in the process of fabricating the semiconductor nanoparticle complex.

[0322] (Comparative Example 4)

[0323] In the process of fabricating the semiconductor nanoparticle composite, 2.0 g of thioglycolic acid PEG ester (molecular weight 470) was used as the mercapto fatty acid ester and 2.0 g of dodecanethiol was used as the aliphatic ligand; otherwise, the semiconductor nanoparticle composite was obtained in the same manner as in Example 1. In addition, chloroform was used as the solvent for measuring the fluorescence quantum yield.

[0324] (Comparative Example 5)

[0325] In the process of preparing the semiconductor nanoparticle complex, 4.0 g of dodecanethiol was used as an aliphatic ligand without adding mercapto fatty acid esters, and the mixture was stirred at 110°C for 60 minutes under a nitrogen atmosphere and cooled to 25°C to obtain the semiconductor nanoparticle complex. The reaction solution containing the semiconductor nanoparticle complex was transferred to a centrifuge tube, 100 mL of acetone was added, and the mixture was centrifuged at 4000 G for 20 minutes, resulting in separation into a clear supernatant and the semiconductor nanoparticle complex phase. The supernatant was removed to recover the remaining semiconductor nanoparticle complex phase. 5.0 mL of normal hexane was added to the obtained semiconductor nanoparticle complex to prepare a dispersion. 50 mL of acetone was added to the obtained dispersion, and the mixture was centrifuged at 4000 G for 20 minutes. After centrifugation, the clear supernatant was removed to recover the precipitate. This operation was repeated several times. Except for this, the semiconductor nanoparticle complex was obtained using the same method as in Example 1. In addition, normal hexane was used as a solvent for measuring fluorescence quantum yield.

[0326] (Comparative Example 6)

[0327] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 0.2 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.2 g of 3-methoxybutyl 3-mercaptopropionic acid was used as a mercapto fatty acid ester and 0.8 g of dodecanethiol was used as an aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0328] (Comparative Example 7)

[0329] In the process of preparing a semiconductor nanoparticle complex, 3.2 g of ethylhexyl 3-mercaptopropionicate was used as a mercapto fatty acid ester and 0.8 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 to obtain the semiconductor nanoparticle complex. The reaction solution containing the semiconductor nanoparticle complex was transferred to a centrifuge tube, 100 mL of acetone was added, and the mixture was centrifuged at 4000 G for 20 minutes, resulting in separation into a clear supernatant and a semiconductor nanoparticle complex phase. The supernatant was removed to recover the remaining semiconductor nanoparticle complex phase. 5.0 mL of normal hexane was added to the obtained semiconductor nanoparticle complex to prepare a dispersion. 50 mL of acetone was added to the obtained dispersion, and the mixture was centrifuged at 4000 G for 20 minutes. After centrifugation, the clear supernatant was removed to recover the precipitate. This operation was repeated several times. Except for that, the semiconductor nanoparticle composite was obtained in the same manner as in Example 1. In addition, chloroform was used as a solvent for measuring the fluorescence quantum yield.

[0330] (Comparative Example 8)

[0331] 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 2-hydroxyethyl 3-mercaptopropionic acid was used as a mercapto fatty acid ester and 0.8 g of trioctylphosphine was used as an aliphatic ligand. This semiconductor nanoparticle complex was not dispersed in chloroform and PGMEA, so fluorescence quantum yield measurements could not be performed.

[0332] (Comparative Example 9)

[0333] A semiconductor nanoparticle complex was obtained in the same manner as in Example 1, except that 4.5 mmol of octanoic acid chloride was used when preparing the dispersion of the core particles, 3.6 g of 3-mercaptopropionic acid-3-methoxybutyl was used as a mercapto fatty acid ester and 0.4 g of dodecanethiol was used as an aliphatic ligand when preparing the semiconductor nanoparticle complex.

[0334] (Comparative Example 10)

[0335] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that octanoic acid chloride was not added during the preparation of the dispersion of the core particles.

[0336] (Comparative Example 11)

[0337] A semiconductor nanoparticle composite was obtained in the same manner as in Example 1, except that 0.3 mmol of indium chloride was added instead of indium acetate when preparing the dispersion of core particles, and chloride octanoate was not added.

[0338] Indium chloride added during the preparation of the core particle dispersion generates hydrogen chloride as a byproduct during synthesis. Consequently, it was found that the halogen content in the finally obtained semiconductor nanoparticles is reduced compared to when a halogen precursor was added during the preparation of the core particle dispersion.

[0339] In addition, the meanings of the abbreviations listed in Tables 1 to 4 are as follows.

[0340] MPAE: Mercapto fatty acid ester

[0341] QD: Semiconductor nanoparticles

[0342] DDT: Dodecanethiol

[0343] TOP: Trioctylphosphine

[0344] EHMP: Ethylhexyl 3-mercaptopropionate

[0345] PGMEA: Propylene glycol monomethyl ether acetate

[0346] [Table 1]

[0347]

[0348] [Table 2]

[0349]

[0350] [Table 3]

[0351]

[0352] [Table 4]

[0353]

[0354] As can be seen from the above results, in Examples 1 to 17, the semiconductor nanoparticle composite has a high fluorescence quantum efficiency (QY) and also has excellent dispersibility in a polar dispersion medium, so it is possible to disperse it at a high mass fraction.

[0355] Meanwhile, Comparative Example 5, which does not use mercapto fatty acid ester; Comparative Example 1, in which the molecular weight of the mercapto fatty acid ester is too high; Comparative Examples 3 and 7, in which the SP value of the mercapto fatty acid ester is too low; Comparative Example 4, in which the average SP of the entire ligand is too low; and Comparative Example 8, in which the average SP of the entire ligand is too high, all have poor dispersibility in a polar dispersion medium, making it difficult to disperse at high mass fractions. In addition, Comparative Examples 2, 6, 9, 10, and 11 had low fluorescence quantum efficiency and low filtration efficiency because the halogen / In of the semiconductor nanoparticles was outside the range specified in the present invention.

[0356] In addition, Examples 1 to 10, in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) is in the range of 300 to 700, have excellent heat resistance, and it was found that the semiconductor nanoparticle composite using the mercapto fatty acid ester represented by general formula (1) in the present invention, having a molecular weight of 300 to 700, is particularly suitable for applications where heat resistance is important. In addition, although the viscosity of the dispersion liquid when dispersed in a dispersion medium in Examples 1 to 10 is higher than that of Examples 11 to 17, which use the mercapto fatty acid ester represented by general formula (1) with a molecular weight of less than 300, it can be used except for applications where low viscosity of the dispersion medium is particularly required.

[0357] In addition, Examples 11 to 17, in which the molecular weight of the mercapto fatty acid ester represented by general formula (1) is in the range of 300 or less, have a low viscosity of the dispersion when the dispersion medium is dispersed. From this, it was found that the semiconductor nanoparticle composite using a mercapto fatty acid ester represented by general formula (1) with a molecular weight of less than 300, as in Examples 11 to 17 of the present invention, does not have the same heat resistance as Examples 1 to 10 using a mercapto fatty acid ester represented by general formula (1) with a molecular weight of 300 or more and 700 or less, but is suitable for applications where low viscosity of the dispersion is more important than heat resistance. Explanation of the symbols

[0358] 1, 101 blue LED 3, 103 LCD 7, 8 QD patterning 9 Diffusion layer 11 cores 12 shells 102 QD film 104 Color Filter(R) 105 Color Filter (G) 106 Color Filter (B)

Claims

Claim 1 A semiconductor nanoparticle complex having a ligand coordinated to the surface of a semiconductor nanoparticle, wherein the semiconductor nanoparticle is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, the semiconductor nanoparticle further comprises a halogen, wherein the molar ratio of the halogen to In in terms of atomic value in the semiconductor nanoparticle is 0.80 to 15.00, and the ligand comprises one or more mercapto fatty acid esters represented by the following general formula (1): HS-R1-COO-R2(1) (wherein R1 represents an alkylene group having 1 to 3 carbon atoms and R2 represents a hydrophilic group), wherein the SP value of the mercapto fatty acid ester is 9.20 or higher, the molecular weight of the mercapto fatty acid ester is less than 300, the average SP value of the entire ligand is 9.10 to 11.00, and furthermore, the ligand and the semiconductor nanoparticle A semiconductor nanoparticle complex characterized by a mass ratio (ligand / semiconductor nanoparticle) of 0.40 or less. Claim 2 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 mol% or more. Claim 3 A semiconductor nanoparticle composite according to claim 1, characterized in that at least one of the shells is formed of ZnSe. Claim 4 A semiconductor nanoparticle composite according to claim 1, characterized in that the shell has two or more layers, and the outermost layer of the shell is formed of ZnS. Claim 5 A semiconductor nanoparticle composite according to claim 1, wherein R2 in the general formula (1) comprises any one selected from the group consisting of an oligoethylene glycol group, a polyethylene glycol group, and an alkoxy group. Claim 6 A semiconductor nanoparticle composite according to claim 1, characterized in that the terminal group of R2 on the side not bonded to -COO- in the general formula (1) is selected from the group consisting of alkyl groups, alkenyl groups and alkynyl groups. Claim 7 A semiconductor nanoparticle composite according to claim 1, wherein the ligand further comprises an aliphatic ligand. Claim 8 A semiconductor nanoparticle composite dispersion in which the semiconductor nanoparticle composite described in any one of claims 1 to 7 is dispersed in a polar organic dispersion medium. Claim 9 A semiconductor nanoparticle composite composition in which the semiconductor nanoparticle composite described in any one of claims 1 to 7 is dispersed in a monomer or prepolymer. Claim 10 A semiconductor nanoparticle composite cured film in which the semiconductor nanoparticle composite described in any one of claims 1 to 7 is dispersed in a polymer matrix. Claim 11 A semiconductor nanoparticle composite obtained by contacting a semiconductor nanoparticle, which is a core / shell type semiconductor nanoparticle having a core containing In and P and one or more shell layers, additionally containing a halogen, wherein the molar ratio of the halogen to In in atomic terms is 0.80 to 15.00, with a surface modification compound having a bonding group that binds to the semiconductor nanoparticle on one side, wherein the surface modification compound comprises one or more mercapto fatty acid esters represented by the following general formula (1): HS-R1-COO-R2(1) (wherein R1 represents an alkylene group having 1 to 3 carbon atoms and R2 represents a hydrophilic group), wherein the SP value of the mercapto fatty acid ester is 9.20 or higher, the molecular weight of the mercapto fatty acid ester is less than 300, the average SP value of the entire surface modification compound is 9.10 to 11.00, and furthermore, the surface modification compound and the semiconductor nanoparticle A semiconductor nanoparticle composite characterized by a mass ratio (surface modification compound / semiconductor nanoparticle) of 0.40 or less.

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